Volkswagen Jetta 1.6 - how many HP - prop calc [Archive]

sailingmonica

10-20-2009, 03:02 PM

Hi to all, new to this forum.

We built our own 42 ft sailboat and marinized a VW Jetta Diesel 1.6 (non turbo, with hydraulic lifters) from a car. It workes great, have already been down South through the ICW and had no problems. Except we cannot seem to be able to figure out the right prop size.

I have subscribed to boatdiesel.com, but in order to get the calc I have to input Hp and RPM. Except I do not know what to enter, because the engine is rated 53 Hp at 4,000 RPM on a car, where there is little resistance. My boat is 42 ft LOL, 31 ft LOW, full keel, propeller in aperture, 30,000 lbs displacement (unloaded), shaft length 70 inches, shaft diameter 1.25 inches, ZF transmission with 2.6:1 ratio in forward, using an Aquadrive system (thrust bearing/CV joint combo). Calculated hull speed 7.3 knots.

Currently I have a 3 blade RH 16X10 propeller. I have good control while docking (very important to me), but pick up speed very slowly and can only get up to maybe 6 knots, if that. And that is at about 3,000 - 3,200 RPM. I can never achieve full rated RPM, but I don't really expect that. All I want to know is how many marine HP can I get from a 53 HP car engine. Has anyone done this before? Any suggestions are welcome and appreciated.

Monica

apex1

10-20-2009, 03:26 PM

Welcome Monica,

the power of your engine does´nt change, no matter which application it is used in. But of course, at the given rpm you will not have the full "rated" hp available. There either the prop diameter is too large, or the pitch to high to achieve the rated rpm.
We have some members here pretty familiar with the VW Golf engines (yours is one), and others skilled on prop settings. And one on both.
Wait they will chime in. CDK..Baeckmo..!!..???

Regards
Richard

marshmat

10-20-2009, 03:38 PM

Hi Monica, welcome aboard the forum.

Your engine has no way of knowing whether it's in a boat or a car- given the same RPM and the same shaft torque, it'll put out the same power. (Of course, there are a few different ways of measuring horsepower, ie. it'll be a bigger number if you measure it at the crankshaft- "BHP"- instead of the propeller shaft, "SHP".) If you got 53 hp at 4000 rpm in the car, and haven't made any modifications to the engine, it'll still make 53 hp at 4000 rpm in the boat. If it's too heavily loaded to reach full RPM, then obviously it won't reach full power either. Of course, sometimes when an engine is marinized, the cam might be changed, injector timing tweaked, etc. all of which will change the ratings.

Generally speaking, a prop is usually chosen so that the engine is fully loaded at full RPM. Since you can only reach about 3200 rpm on an engine that is meant to rev up to 4000, your prop is probably a bit too big. Or it might just be a mass of weedy barnacles- worth checking. Being unable to reach full RPM means that the engine is, somehow, overloaded- which can greatly reduce its lifespan.

A 16" dia. by 10" pitch 3-blade prop sounds to be in the right ballpark for the specs you've provided. (A very rough calculation suggests 17x10 as a starting point.) Thus, I am suspicious that either your prop is not what it appears to be, or your engine has been detuned to a fair bit below its rated 53 hp. The former problem calls for an inspection and possibly repair/replacement of the prop; the latter problem would call for engine repair (if faulty) or a smaller diameter, lower pitch prop (if the engine has in fact been detuned).

Finally, your relatively heavy, 31' LWL full-keel yacht is not going to do any better than 7 knots under power, tops, and roughly 50 hp should be in the right ballpark for a hull of this weight.

apex1

10-20-2009, 04:06 PM

Somehow I did know it will be one I did not mention!
Sorry Matt..........

baeckmo

10-22-2009, 03:46 PM

Oops, didn't observe the challenge, ya know how to tease me Richard!! Lady in distress and all.........

In addition to Matt's advice, let's check your existing setup; there is something weird somewhere. A preliminary calc shows that a 16x10 prop, running ~1190 rpm as yours does, will only use about 15 hp, and supply some 1630 Newtons of thrust at 6 knots, provided it is not completely fouled by seaweed or totally hidden behind a thick, square lump of keel structure.

With this prop your engine should be running full rpms, ie at the governor limited speed (~4100-4200 rpm) if it is what it says. My first guess is that the prop is not clean.

But this screw is not correct anyway, I would rather see a 17*11, giving ~3900 rpm at ~7 knots (thrust 4000 N), provided the engine is not de-tuned or suffers from high exhaust back pressure or faulty fuel system (check how the fuel return from injection pump is installed).

So, first get wet and check what you have down below!

Angélique

10-22-2009, 06:25 PM

... or totally hidden behind a thick, square lump of keel structure.

Take a look: pic. ‘‘Monica’’ from behind (http://www.boatdesign.net/forums/attachments/open-discussion/36439d1256245577-hello-toronto-monicaonlandsternview.jpg) ;)

See also this thread: Hello from Toronto (http://www.boatdesign.net/forums/open-discussion/hello-toronto-29818.html)

Nice story Monica and a beautiful boat !!

Regards, Angel

marshmat

10-22-2009, 09:34 PM

Looks clean enough to me.... and Toronto isn't exactly prime territory for fouling organisms.

So we're more likely looking at an engine not making its supposed rated power- maybe it was detuned a bit during marinizing, maybe there's a back pressure problem, maybe the reduction gear isn't as steep as it says..... even so, baeckmo's calcs suggest that you shouldn't need full power anyway, so what else could be going on..... hmmm..... this isn't one of those computerized motors, is it?

Angélique

10-22-2009, 11:47 PM

Were the bottom and propeller just as clean as the picture shows when the problems occurred? In a one year cruise ‘‘Monica’’ could have been in prime territory for fouling organisms and cleaned afterwards. If it is a current picture, in what state came the boat out of the water?

Regards, Angel

CDK

10-23-2009, 03:01 AM

liki

10-23-2009, 03:23 AM

Would the engine in question be 1.6D JP or ME or similar, 40kW@4800rpm and 100Nm at 2300rpm. Torque peak translates into a little over 24kW.

If it can provide still 90Nm at 3200 rpm, it should mean power output (maximum) of about 30kW. 90Nm@3200 rpm is a pure guess.

apex1

10-23-2009, 05:39 AM

Cornelis you´re too humble!

Liki, you should translate JP or ME, except for CDK and Baeckmo (and me), there will hardly anyone else understand what you are referring to.

Nice boat Monica!

liki

10-23-2009, 05:45 AM

you should translate JP or ME

Yes, these are VAG motor type codes, telling the exact type of the engine. Otherwise meaningless, but the correct engine rating can be found out if the type is known - It should be marked somewhere in the engine block or head.

Angélique

10-23-2009, 10:16 AM

... the engine is rated 53 Hp at 4,000 RPM on a car

The engine is most likely rated 54.8 Hp (40.3 kW) @ 4,800 rpm (engine #1) or 50.7 Hp (37.3 kW) @ 5,000 rpm (engine #2). See engine spec's below.

... pick up speed very slowly and can only get up to maybe 6 knots, if that. And that is at about 3,000 - 3,200 RPM. I can never achieve full rated RPM

Looking at the data that Matt, baeckmo and liki have provided the prop should be a piece of cake for the engine.

What is the max rpm with the transmission in its neutral position? If there is no engine problem, and its not detuned, it sould be easy to reach 4,800 rpm for engine #1 and 5,000 rpm for engine #2.

Matt / baeckmo / liki / CDK, till what rpm and for how long (short) can she safely test it while running unloaded?

If you can't reach the 'max-power' rpm while running unloaded then its maybe a governor problem. Or just the screw on the fuelpump -that limits the full throttle position of the leverage wich is connected to the throttle handle- is to far out. Dirt in the fuel system can also be the problem.

From your information I gather that you have the first of the two engines below. If not then I guess its the second.

1983+ Volkswagen Golf 1.6 Diesel (engine #1)

http://www.carfolio.com/specifications/models/car/?car=38577

- Bore × stroke: 76.50 mm × 86.40 mm, 3.01 in × 3.4 in
- Cylinders: Straight 4
- Displacement: 1.6 litre, 1588 cc, (96.906 cu in)
- Type: Single OverHead Camshaft, 2 valves per cylinder, 8 valves in total
- Compression ratio: 23.00:1
- Fuel system: Bosch diesel inj.
- Maximum power: (DIN) 54.8 HP/PS/PK/CV/... (54.0 bhp) (40.3 kW) @ 4800 rpm
- Specific output: 34 bhp/litre, 0.56 bhp/cu in
- Maximum torque: (DIN) 100.0 Nm (74 ft·lb) (10.2 kgm) @ 2300 rpm
- bmep = Brake Mean Effective Pressure: 791.3 kPa (114.8 psi)
- Specific torque: 62.97 Nm/litre
- Maximum rpm: ????
- Main bearings: 5
- Coolant: Water
- Bore/stroke ratio: 0.89
- Unitary capacity: 397 cc/cylinder
- Aspiration: Normal D. (atmospheric pressure)
- Compressor: None
- Intercooler: None
- Catalytic converter: None

1978+ Volkswagen Golf L Diesel (engine #2)

http://www.carfolio.com/specifications/models/car/?car=43032

- Bore × stroke: 76.50 mm × 80.00 mm, 3.01 in × 3.15 in
- Cylinders: Straight 4
- Displacement: 1.5 litre, 1471 cc, (89.766 cu in)
- Type: Single OverHead Camshaft, 2 valves per cylinder, 8 valves in total
- Compression ratio: 23.50:1
- Fuel system: Bosch diesel inj.
- Maximum power: (DIN) 50.7 HP/PS/PK/CV/... (50.0 bhp) (37.3 kW) @ 5000 rpm
- Specific output: 34 bhp/litre, 0.56 bhp/cu in
- Maximum torque: (DIN) 80.0 Nm (59 ft·lb) (8.2 kgm) @ 3000 rpm
- bmep = Brake Mean Effective Pressure: 683.4 kPa (99.1 psi)
- Specific torque: 54.38 Nm/litre
- Maximum rpm: ????
- Main bearings: 5
- Coolant: Water
- Bore/stroke ratio: 0.96
- Unitary capacity: 367.75 cc/cylinder
- Aspiration: Normal D. (atmospheric pressure)
- Compressor: None
- Intercooler: None
- Catalytic converter: None

When was the last distribution belt replacement? It has nothing to do with this problem but to avoid serious problems in the future its best to replace it on time.

Regards,

http://images.zaazu.com/img/000354-small.gif (http://images.zaazu.com/img/000354-large.gif) Angel http://images.zaazu.com/img/000354-small.gif (http://images.zaazu.com/img/000354-large.gif)

P.S.
Jeff / Monica, I see four posts of Monica in two threads, but Monica's post number is still at one. Is there a problem?

Jeff

10-23-2009, 11:34 AM

P.S. Jeff / Monica, I see four posts of Monica in two threads, but Monica's post number is still at one. Is there a problem?Posts in the Open Discussion and Forum Questions & Suggestions forums do not increment a user's post count since they're considered more friendly conversation rather than the rest of the forums which are more closely on-topic and/or technical in nature.

Angélique

10-23-2009, 01:05 PM

The possiblity of too much back pressure -and much more- has already been mentioned (baeckmo & Matt) but how is the air intake? Is it sufficient? Engine #1 has to take in -without to much resistance- 1,588 L / 4 stroke x 4,800 rpm = 1,906 L/min = nearly 2 m³ air per minute. Matt / baeckmo / liki / CDK, how big a hole do you need for that also taking into account the resistance of the air filter? Monica, does your air intake match with that figure (hope it comes) :) And... is the air filter clean ?

Regards,
Angel http://images.zaazu.com/img/000274-small.gif (http://images.zaazu.com/img/000274-large.gif)

P.S. Thanx for the info Jeff !!

CDK

10-23-2009, 01:33 PM

Air intake:
Anything over 50 mm or 2" is fine.
And no air filter on a marine diesel, just a piece of wire mesh to keep the mice out. But it doesn't matter, Monica's problem is not related to the air intake.

sailingmonica

10-23-2009, 02:19 PM

Thank you all for your help. I am sorry if I provided incorrect/incomplete info.

The engine is a VW Jetta Diesel, 1.6, with hydraulic lifters and non turbo. The problem is that we do not know the year of the engine. We were told that they were made non turbo but with hydraulc lifters for a short period of time somewhere between 1984 and 1988. Matt, it is not computerized, all mechanical.

When Angelique and Liki questioned the HP and RPM I started to call around. Dealerships shot me down as I could not provide the year. The Partsplaceinc in Michigan told me it could be 52 HP at 4,800 RPM, but they are not sure. I registered on jettajunkie dot com and I asked the question on the forum. Waiting for feedback.

The prop is not fouled in any way, never was. The keel, however, is thick (internal ballast) but we narrowed it towards prop to allow for good water flow. I will measure this weekend and provide info (boat is hauled out right now).

I was trying to upload two pictures of the propeller area but they seem to exceed the limit allowed. Anything I can do to fix that?

liki

10-23-2009, 02:30 PM

When Angelique and Liki questioned the HP and RPM I started to call around.

Just trying to provide you the correct data and some estimates what the engine could deliver at the revolutions you are reaching when everything is operating correctly.

sailingmonica

10-23-2009, 02:41 PM

Liki, I am grateful for the fact that you and Angelique questioned the data I provided. A propeller is not cheap and by you asking the question you may have saved my both $$ and aggravation. Please don't think that I meant to cricize you, I would actually hug you if I could.

I don't know where my husband got the 53 HP at 4,000 RPM info, but I will get to the bottom of this. Please do not give up on me just yet.

apex1

10-23-2009, 03:28 PM

Monica, I gues the engine data was somewhere in the cars documents, and should be assumed right, for now.

Liki
can you narrow that down a bit by the info given so far? Golf 1,6 ltr., hydr. lifters, around 54hp, will be in your data base.

Cornelis
And who said he does´nt take the bait?

Angelique
there are more than just two possibilities. And the second engine you listed seems to be out of the choice.
And as Cornelis said: there are no air filters on a marine diesel! Therefore no restriction.

Regards
Richard

sailingmonica

10-23-2009, 03:45 PM

Apex1, what I did not mention is the fact that, while initially we bought a VW Jetta Diesel car 1.6 from 1984 and used that engine for a while (non hydraulic lifters), we recently bought and installed the engine we currently have (with hydraulic lifters, does not make that clickety clickety noise that the one before was making). As I said, the guy that sold this motor to us had it sitting on blocks and, well, the serial number on the engine block that could have given us clues as to the year it was made was filed off.

The data I provided did not come from any document, but was rather something someone told my husband. Sorry.

apex1

10-23-2009, 03:51 PM

Oho,
that makes the research serious!
Now the Finnish fraction is asked to go deep into their data base. (they know the brand of the watch of the guy who first started your engine)
But even they like to know some basic data first.
Well lets see, if he can help.
Otherwise you can try to climb the hill in reverse gear! Bodo will assist in finding the issue through the prop data.
I told you, you´re not lost. And we lured the right ones!!!

Richard

sailingmonica

10-23-2009, 04:10 PM

I will look at the engine with a magnifying glass for any info. I will also take pictures and will try to upload, if the size limitation will allow.

If this helps, the fuel injection pump on the engine has the number 068 130 081C on it. The partsplaceinc told me that based on the pump number the engine is probably a 86-87. At least that is what they think.

marshmat

10-23-2009, 04:27 PM

If you can't reach the 'max-power' rpm while running unloaded then its maybe a governor problem. Or just the screw on the fuelpump -that limits the full throttle position of the leverage wich is connected to the throttle handle- is to far out. Dirt in the fuel system can also be the problem.
That's starting to sound more and more plausible as the information on this boat and engine comes out. If this engine were so badly overloaded that it couldn't get past three thousand revs, I'd think we would have been told about a black-smoke-at-full-throttle issue by now.

Is the throttle linkage moving through its full range, ie. does full-forward on the control lever match up with wide-open position at the engine?

Angélique

10-23-2009, 08:00 PM

... the guy that sold this motor to us had it sitting on blocks and, well, the serial number on the engine block that could have given us clues as to the year it was made was filed off.

In that situation it could have been a turbo engine without a turbo that was sold to you. Eg the turbo was broken and the exhaust manifold etc. was changed for one from a non turbo engine. In that case you have a perfectly good running engine with very low power. It could be the type in the spec's below. But if that's the case a lot of the spec's has been changed. Especially those relating to the power and torque and the corresponding rpm's. If the turbo is removed and nothing is done to the characteristics of the engine to equal that of a standard non turbo engine then the power and torque will be much lower than that of a standard non turbo engine.

I hope that it is not that and that it appears to be something simple such as the non max throttle thing. etc.

But obviously the filed off numbers are an clear indication never to buy such thing. It could be a stolen engine or a engine from a stolen car. Or a cover up for a broken turbo and the non turbo thing. The numbers are never filed off for no reason.

1985+ Volkswagen Jetta CL TD

http://www.carfolio.com/specifications/models/car/?car=16258

- Bore × stroke: 76.50 mm × 86.40 mm 3.01 in × 3.4 in
- Cylinders; Straight 4
- Displacement: 1.6 litre 1588 cc (96.906 cu in)
- Type: Single overhead camshaft, 2 valves per cylinder, 8 valves in total
- Compression ratio: 23.00:1
- Fuel system: Bosch diesel inj.
* Maximum power: (DIN) 70 HP/PS/PK/CV/... (69.0 bhp) (51.5 kW) @ 4500 rpm
* Specific output: 43.5 bhp/litre 0.71 bhp/cu in
* Maximum torque: (DIN) 133.0 Nm (98 ft·lb) (13.6 kgm) @ 2600 rpm
* bmep = Brake Mean Effective Pressure: 1052.5 kPa (152.6 psi)
* Specific torque: 83.75 Nm/litre
* Maximum rpm: ????
- Coolant: Water
- Bore/stroke: ratio 0.89
- Unitary capacity 397 cc/cylinder
* Aspiration: Turbo D.
- Catalytic converter: None

Things that dramaticly change after the removal of the turbo are marked with an * in the spec's.

Regards, Angélique

Steve W

10-23-2009, 09:06 PM

Would you not want to be geared and propped for the rpms that the engine produces its maximum torque rather than hp? I have a VW passat tdi which is a computerized engine and one which i have thought would be a nice boat motor and the owners manual shows maximum hp at something like 4800rpm but maximum torque at 1900rpm,i dont see any relevance at all to the hp figure as i drive the torque and rarely see over 3000rpm even going thru the gears,i sure wouldnt want to be motoring at anything near max rpm with it in a boat but it would be quiet and smooth at 2k,what am i missing?
Steve.

sailingmonica

10-23-2009, 09:51 PM

OK, for all it's worth I am going to give you everything I can think of.

I had this same engine working with a ZF transmission with a 1.9:1 reduction ratio. I used the same propeller I have now, 16X10.

The boat did not have very good docking (low speed) maneuvreability. In order to control the boat while docking had to keep putting it in and taking it out of gear.

When taking off in forward from a stopped position, such as exiting a lock, I would put it into gear and push the throttle 50-75%. The boat would jump ahead vigorously and pick up speed quickly. But, the RPM would drop fast and the boat would stay at about 5.1 to 5.4 knots. When pushing the throttle at max, in perfect conditions of no wind and current we could reach 6.9 knots, but took a long time to get there, maybe 5 minutes. So basically we could get up to 5 knots fast and took way longer to get up from there.

With 25 knots of wind on the bow, the speed would drop from, say, 6.3 knots to 3 knots. Same if going against current. There is a narrow channel in the ICW called Snow Cut where we encountered a current of 4 knots. Before entering the cut our speed was 5.4 knots and it dropped to less than 2 knots in the cut.

We then changed the transmission to a ZF with a 2.63:1 ratio, because we did not want to subject the Aquadrive to too high RPM. I now have good docking capability, but can no longer push throttle and take off fast. If I push throttle fast the boat does not move immediately, but slowly in time. It will not "jump" any more.

I may be asking too much, but what I am hoping to achieve is a balance between good docking capabilities, quick response and decent cruising speed.

Does any of this has any meaning?

sailingmonica

10-23-2009, 10:03 PM

Steve W, I absolutelly see your point. But, in order to calculate what propeller I need I have to input into the program "maximum HP" and "maximum RPM". Of course, the program was created for marine engines, where I assume you can state whatever the engine is rated for. What should I enter in my case?

Steve W

10-24-2009, 01:50 AM

Yeah,i dont know what you would need to enter into the program,you may want to contact the folks who marinised the vw diesel and called it the Pathfinder,i think they are in Canada,they must have some kind of formular they used to recomend prop sizes and reductions for different boats when they sold the engines.Good luck.
Steve.

CDK

10-24-2009, 05:53 AM

Some questions:

1. When not in gear, what is the max rpm you can reach?
2. Is there any black smoke at full throttle and load?
3. Is there gray smoke and the smell of diesel at idle?
4. What did you do with the start assist lever at the back of the fuel pump?

liki

10-24-2009, 07:39 AM

If this helps, the fuel injection pump on the engine has the number 068 130 081C on it.

Using the evidence at hand, VAG spare parts catalog tells that his pump has been used on ' 86 Jetta 1.6 D and TD, engine models JP an JR.

So, all together I'd believe the engine to be 1.6D JP, as I wouldn't believe many to bother with stripping a broken turbo to sell the engine as naturally aspirated for a few hundred. 40kW@4800rpm and 100Nm@2300 rpm should be correct, or atleast very close to the correct values, with the engine in pristine condition.

Angélique

10-24-2009, 09:57 AM

... I wouldn't believe many to bother with stripping a broken turbo to sell the engine as naturally aspirated for a few hundred.
You don’t need many, only one. And you would be suprised by what people would do for a few hundred or less. The numbers are never filed off for no reason.

@ Monica, Was there a exhaust manifold on the engine when you bought it? Or was it taken off already as you needed a marine one anyway?

Regards,
Angel

sailingmonica

10-24-2009, 09:59 AM

Marshmat, the throttle linkage is moving at full range

CDK,

When not in gear max RPM reached is 3,800 - 3,900
Under full load, if throttle is pushed quickly to max there is really black smoke, like from burning rubber, the kind that you can see on the water surface as it is eliminated with exhaust water. It is not oil, more like the stuff you get in your chimney. If throttle is increased gradually to max under load, there is no black smoke.
There is no black smoke at highest RPM when not in gear.
There is no grey smoke or diesel smell at idle.
Can you clarify what do you mean by the last question related to the start assist lever?

Liki,

The 40 Kw converts to 53.6 Hp. If I input 53 Hp and 4,800 RPM in the boatdiesel program, it gives me a 3 blade 15.3 diameter with 7.5 pitch. Looks kinda small, especially given that I have a full keel and my prop is in aperture.

I can't seem to wrap my mind around this. If maximum torque of 100 Nm is reached at 2,300 RPM, and the rest of the RPM range all the way to 4,800 is useless to me, should I then calculate based on 2,300 RPM? If yes, do I still enter 53 Hp at 2,300? Because if I do, I get diameter 23.8 and 15.6 pitch, which looks pretty big.

If it is not 53 Hp at 2,300 RPM, how can I determine Hp?

liki

10-24-2009, 10:12 AM

I can't seem to wrap my mind around this. If maximum torque of 100 Nm is reached at 2,300 RPM, and the rest of the RPM range all the way to 4,800 is useless to me, should I then calculate based on 2,300 RPM?

Power = Torque times revolutions in radians per seconds.

100Nm at 2300 rpm is a little over 24kW in power, and the rest of the rpm range is not useless, although the torque decreases. The maximum power output is still at 4800 rpm, and gearing increases torque at shaft directly in proportion to the gearing.

40kW at 4800rpm is a little under in 80Nm torque.

CDK

10-24-2009, 12:54 PM

CDK,

When not in gear max RPM reached is 3,800 - 3,900
Under full load, if throttle is pushed quickly to max there is really black smoke, like from burning rubber, the kind that you can see on the water surface as it is eliminated with exhaust water. It is not oil, more like the stuff you get in your chimney. If throttle is increased gradually to max under load, there is no black smoke.
There is no black smoke at highest RPM when not in gear.
There is no grey smoke or diesel smell at idle.
Can you clarify what do you mean by the last question related to the start assist lever?

To start with the last sentence:
VW engines from that era had a device to facilitate cold starting. It was a lever mechanism on the back of the injection pump to simultaneously advance the injection timing and reduce the spring pressure against the governor assembly, resulting in more time for the mixture to burn and increase idle rpm from 900 to 1100.
On some models the mechanism was operated manually with a bowden cable, while others had an aneroid thermostat.
If there was a manual control, the lever should be secured in a position where the idle rpm just starts to increase. Leaving the lever free will cause it to drop and retard the ignition start, resulting in insufficient combustion time and consequently a reduction of power.

Rpm without load:
With a proper throttle link mechanism and correct injection timing, the rpm should be 400-500 above the rated rpm/hp. For your engine, regardless of the engine code, that would be almost 5000 rpm.
When you look at the top of the Bosch VE-pump, you see a stop screw the throttle lever is pulled against. Turn it out a few turns and check max. rpm again. If it makes no difference, something is wrong with the governor and in that case the pump needs service.

Black smoke under full load:
That means the engine gives all it can but there is too much load. Since you don't see that, there is no such problem. Baeckmo told you in post #5 what the actual power delivered to the prop is; there will also be some loss in the gearbox but not more than a few hp., so the engine clearly doesn't generate what it should be capable of.
Below the 4 nuts that attach the injection lines to the pump you can see a capped screw with a nut. If you loosen the nut and turn the screw clockwise for half a turn at a time, full output power is increased considerably, but it also shifts the idle rpm somewhat. If you see black smoke at full rpm under load, you've turned too far.

Grey smoke and fuel smell at idle:
There is insufficient internal pump pressure to keep the injection timing within range. That is caused by a fuel return line without the proper restrictor.
The banjo bolts on top of the fuel pump look the same but the one from the return line has a very small hole compared to the other one.

baeckmo

10-25-2009, 07:56 PM

Ha, everybody been busy here, while I've been in the woods over the weekend, training the dogs for moose tracking....! Good job folks!

After this first round, we can conclude that there are uncertainties regarding the engine. Before we can dig into the propeller details, we must be safe on the engine side:

1/ The engine tachometer should be checked for calibration, using a separate light-beam tacho or similar for comparison (borrow/hire from engine shop).

2/ Engine room ventilation deep down in the boat should give an engine room temperature of 40 degr C at the absolute maximum, preferably lower. Engines are radiating heat at a rate of 10 to 20 percent of shaft power, depending on design. This has to be ventilated away. Vent openings should be minimum 7 cm2 per kW, in this case 2 openings 140 cm2 each, arranged so that a natural draft is created. This incudes area for combustion air.

3/ The return fuel must circulate all the way back to the tank, in order to dissipate the vapour bubbles and heat generated in the injection pump. Some VW engines have a thermostatically controlled shunt in connection with the fuel filter, diverting cold fuel back into the pump suction line. This device includes a calibrated nozzle that gives the correct back pressure for the injection pump housing. Iiki would probably be able to see the original configuration of your engine. The shunt should not be used in a marine engine, but the nozzle is important.

4/ Marine exhausts often differ from car types in terms of piping configuration. 4-cyl car engines today practically always have cyl's 1 plus 4 and 2 plus 3 connected in groups before they join together. This gives better and more equal gas exchange than the common inline arrangements we see on most watercooled marine manifolds. The result is a power loss from "car power" to "marine power" of about 10 percent, giving your engine 49 hp at max rpm's. The exhaust back pressure should not be more than ~1.2 m water column, preferably 0.6 m max. Excessive back pressure could result in lowered max rpm's (even in no-load high idle) due to the pumping power needed. Until this is checked, we don't know if the speed governor is ok! If you use a water-cooled system, the hose innerdia should not be less than 60 mm, preferably 75, since there probably is a pretty lengthy piping in your boat.

5/ The reduction ratio 2.63 to 1 gives a relatively high rotational speed to your propeller, making it very highly loaded (I would have preferred something like 3.5 or 4 for this engine). You might say that the area swept by the propeller is too small to give it authority over the mass and area of the boat. This is why we have to be very careful, so that we use the power installed to its optimum. As a result, the selection of propeller may not follow normal standard routine; I will return to this when we know your engine limitations better.

Hope I haven't flipped your nose with obvious statements in the list; just got to be methodic in search of engineering "truth".

Ad Hoc

10-25-2009, 10:24 PM

Just a minor addition to baeckmo's excellent summary in point 2, as a good rule of thumb:

Whatever combustion air by volume intake is required by the engine, call that V, then the air into the ER is 2V, 1V for the engine and 1V for the venting. This is for a standard 10degree temp rise over ambient.
If you wanted only say a 5 degree rise, then you would need 2V for the ER, ie a total of 3V.

liki

10-26-2009, 03:23 AM

Under full load, if throttle is pushed quickly to max there is really black smoke, like from burning rubber, the kind that you can see on the water surface as it is eliminated with exhaust water. It is not oil, more like the stuff you get in your chimney. If throttle is increased gradually to max under load, there is no black smoke.

This sounds a little like the engine is already giving out the maximum torque it can provide in its present condition, especially as it is slow to pick up revolutions. Since the engine should be able to deliver more then enough power and torque with also the current gearing there likely exists some mechanical or adjustment problem.

Some things to check, in no particular order:
a) Compression test
b) Cam shaft / toothed belt timing
c) Worn cam shaft / valve mechanism
d) Condition of injectors
e) Injector pump condition and especially injection timing

All these tests are fairly easily performed, perhaps save for injection timing adjustment. If you plan to check these matters yourself, you should find http://vagcat.com helpful.

Jasonsansfleece

10-27-2009, 06:47 PM

Given the engine is circa 1985, spent its previous life in an automobile and has already done many thousands of miles, unless its been rebuilt its probably worn out.
A compression check on each cylinder will confirm this.

The injectors are good for 60,000 miles or so, the "pop" pressure will be out of spec and the spray pattern might not look so good.

The Injection pump timing should be checked as well as the pump internal pressure as this affects timing advance.

I mention all of the above as they all adversely affect engine output.

Even if the compression ratios are within specs ( or not far out) I would recommend looking into the injectors and pump.

Although is primarily a car forum, these folks know alot about these particular engines
http://www.vwdieselparts.com/forum/

Guy

sailingmonica

10-28-2009, 05:07 PM

Guys, I cannot thank you enough for taking the time to research in order to help me solve my problem. As for my nose, I don't mind it when it is flipped by smart people, and I love learning from you.

A fellow boater used to own a Corbin 39 which had a Pathfinder engine and even though he sold the boat he kept a copy of the manual.

These are the specs: Pathfinder 1.5, Max output 37 kW (50 BHP) @ 4,500 RPM, Max torque 82 Nm (71 ft/lb) @ 2,500 RPM, Continuous rating - pleasure craft 36 kW (42 BHP) @ 4,000 RPM. He had a 2.63:1 transmission as well. While he doesn't remember the displacement of the boat, I assumed it lighter than mine, say 25,000 lbs. Since 1 PS = 0.98632 SAE and from what I understand 1 PS is the same as 1 BHP (correct me if I am wrong), for the sake of simplification we can say that they are all equal.

Now, this boat had a 19X13 propeller. And it worked well. How on Earth is this possible, because if I enter all the Corbin's data in the program I am way off in the result.

Going now back to my boat:

- I agree with the tachometer perhaps giving false readings. It is connected to the alternator via the W connector, so it is actually reading the RPM from the alternator.
- The timing is OK
- The injectors are new
- The engine is an '86 but was rebuilt, good compression ratio
- Exhaust hose is not that long, it comes out on the side, above waterline, not at the stern. Hose inner dia is more than 60 mm.
- Return fuel circulates back to tank.
- Engine room is spacious and is ventilated to the outside

Let's assume for a moment that my engine is in perfect condition. Then, car engine on a boat equals 90% of HP? Can I then calculate my prop based on 49 HP at 4,800 RPM?

The thing that bothers me about the calculation is that nowhere does it ask you whether the propeller is an aperture or does it have free water flow. I am no expert, but common sense dictates that there have to be some differences based on that.

Angélique

10-28-2009, 08:04 PM

A fellow boater used to own a Corbin 39 which had a Pathfinder engine and even though he sold the boat he kept a copy of the manual .... doesn't remember the displacement of the boat ....
I found this (http://i.pbase.com/u35/lesterhel/large/23307553.page7.jpg) and this (http://i.pbase.com/u40/lesterhel/large/26336181.July2120028.jpg) but I can't read it (you could try to increase it, I didn’t). Or you may find the Corbin’s displacement here (http://www.corbin39.com/) or ask for it to compare it with your boat.

.... Pathfinder 1.5, Max output 37 kW (50 BHP) @ 4,500 RPM, Max torque 82 Nm (71 ft/lb) @ 2,500 RPM
That sounds a lot like the 1.5D engine#2 at post#13 (http://www.boatdesign.net/forums/diy-marinizing/volkswagen-jetta-1-6-how-many-hp-prop-calc-29793.html#post309284) only the rpm's are 500 lower and torque is +2 Nm. I saw a Corbin 39 1981 brochure (http://www.pbase.com/lesterhel/the_original_corbin_39_brochure) (page say's ‘‘that might have been purchased in 1979’’). So that could match with the listed 1978+ engine#2. The Pathfinder marinized version of it could have modifications to lower the rpm's by 500 and + the torque by 2 Nm, and keep the same power!!...?? Maybe if you can figure out how that's done on the Pathfinder you can do it too.

P.S. about the torque of engine#2 vs. the 1.5 Pathfinder. It could have been that Pathfinder has translated 8.2 kgm into 82 Nm which sould have been 80 Nm.
P.P.S. torque data of the 1.5 Pathfinder ‘‘82 Nm (71 ft/lb)’’ is not correct: 82 Nm = 60.5 ft·lb and 71 ft·lb = 96 Nm.

.... for the sake of simplification we can say that they are all equal.
If you want to end up with the right prop size you can't say ‘‘they are all equal’’. There are to many differences between engine#1 and #2 at post#13 (http://www.boatdesign.net/forums/diy-marinizing/volkswagen-jetta-1-6-how-many-hp-prop-calc-29793.html#post309284) to say so. The 1.5 Pathfinder is most likely a marinized version of engine#2 and you most likely have something like engine#1.

Going now back to my boat: .... The engine is an '86 ....
That sounds like a bit newer as the listed 1983+ 1.6D engine#1 at post#13 (http://www.boatdesign.net/forums/diy-marinizing/volkswagen-jetta-1-6-how-many-hp-prop-calc-29793.html#post309284), except from the fact that the listed engine#1 has non hydraulic lifters the rest of the spec's could be the same as your engine.

Liki, about post#31 (http://www.boatdesign.net/forums/diy-marinizing/volkswagen-jetta-1-6-how-many-hp-prop-calc-29793-3.html#post309629), does the 1986 1.6D JP engine have hydraulic lifters? Or are the hydraulic lifters only on the 1986 1.6TD JR version of these two?

Succes !!

Regards,
Angel.

P.S. about 12 small additions and changes in the first 2 hours, so earlier readers there is some additional info.

P.P.S. (10-29-2009)
.... I understand 1 PS is the same as 1 BHP (correct me if I am wrong)
They are almost the same: It is Horsepower = HP/PS/PK/CV/etc. vs. brake horsepower = bhp

Eg engine#1: Maximum power: 54.8 HP/PS/PK/CV/etc. = 54.0 bhp = 40.3 kW @ 4800 rpm
Eg engine#2: Maximum power: 50.7 HP/PS/PK/CV/etc. = 50.0 bhp = 37.3 kW @ 5000 rpm

See: HP Horsepower (http://en.wikipedia.org/wiki/Horsepower) / PS Pferdestärke (http://de.wikipedia.org/wiki/Pferdest%C3%A4rke) / PK Paardenkracht (http://nl.wikipedia.org/wiki/Paardenkracht) / CV Cheval-vapeur (http://fr.wikipedia.org/wiki/Cheval-vapeur) / etc. They all also mention bhp (brake horsepower).

baeckmo

10-28-2009, 09:23 PM

You friend's figures fit perfectly well, Monica. But first your question on propeller working in an aperture (or any structure that obstructs flow). That is influencing the propeller as if the inflow velocity is lower than the actual speed of the vessel. So, when your vessel is making 7 knots through the water, the propeller only "feels" a mean advance speed of about 85 % of this, say 6 knots, or 3.06 m/s.

Then to the engine characteristis. The maximum power is varying with rpm; at 2000 rpm you have ~29 hp at the shaft, at 3000 rpm there is 39 hp, at 4000 rpm 47 hp, topping 51 hp at 4800 rpm. A rough first indication on propeller diameter (in inches) is:

D=630 * hp^0.2/(shaft rpm)^0.6;

If we check the performance at 3100 engine rpm's, available power should be ~41 hp and, alas the prop dia for this point of operation will be 19". Now, your engine only pulls a 16" propeller at this rpm, which tells us that there is something wrong; either is the power restricted, or the gear ratio is ~2:1 instead of 2.63:1. CHECK THAT THE GEAR RATIO IS SAME IN BOTH DIRECTIONS! These things have to be settled first of all, hence my previous questions.

Now, given that your engine and transmission is ok, we can make a (more) complete analysis of the options. The 19 x 13 prop would give you 3100 rpm on the engine and produce a force on the hull of 3978 N at 7 knots.

If we want to use more of the available engine power, we have to let it spin faster, say 3800 rpm. To do that, a smaller propeller is used, here a 17 x 12 would be the choice, resulting in a thrust of 4191 N at the same hull speed. Here, the engine is producing ~46 hp. This is a 12 % increase in power for 5 % increase in thrust, demonstrating the importance of low propeller load. The "classical" prop load factor is the Taylor load factor; Bp=(shaft rpm)*sqrt(hp)/(knots)^2.5, where "knots" is the advance speed.

If you put your data into the Taylor load factor, you get very high figures, in fact so high, that a Kort nozzle, as used on tugs would be appropriate. But that would conflict with sailing performance of course....

So, back to the dirty checking, remember that propeller power is depending on rpm^3; any error in rpm readings give gross errors in power estimation.

liki

10-29-2009, 04:09 AM

Liki, about post#31, does the 1986 1.6D JP engine have hydraulic lifters? Or are the hydraulic lifters only on the 1986 1.6TD JR version of these two?

The only difference in cylinder head, cam shaft and valve assembly for 1986 JP / JR engines seems to be different exhaust valve, and neither engine seems to be equipped with hydraulic lifters. Also, a different model of cylinder head seems to be possible.

sailingmonica

10-29-2009, 07:48 PM

Liki, I just wanted to say that it is my understanding that the engines that did not have hydraulic lifters didn't have that additional hole in the block with a corresponding hole in the head to allow more oil to circulate for the lifters. My engine and head have these holes. So, while the fuel pump part number indicated an '86, the hydraulic lifters seem to indicate maybe a newer model. In any respect, it's a Frankenstein but I like it.

I wanted to buy a VW marine SDI - 40 but it is computerized and that is not a good thing on the boat, so I'll stick with what is simple to fix and parts are available anywhere (this being the reason why we chose to go VW in the first place).

Baeckmo, the transmission is a ZF 12 brand new, 2.63:1 in forward and 1.95:1 in reverse and it is connected correctly. Couldn't find a higher reduction ratio transmission that would fit.

liki

10-30-2009, 02:43 AM

My engine and head have these holes. So, while the fuel pump part number indicated an '86, the hydraulic lifters seem to indicate maybe a newer model. In any respect, it's a Frankenstein but I like it.

Okay, do not give up just yet. :) After all I can tell you about the engine is:
a) The pump part number matches a 1986 Jetta 1.6D
b) Should the engine be from a 1986 Jetta, it is most likely 1.6D JP with the aforementioned specs.

The head might well be replaced with a spare part that has the oil channels as the same head is used on a few different engines and especially the spares are made to fit even a larger variety.

As the engine is rebuilt, I'd suspect that the lack of output is due to timing misalignment.

CDK

10-30-2009, 04:01 AM

Sailingmonica, if you have doubts about the tacho you can use the rpm-to-sound program and a laptop to check the accuracy. I did the same for my instruments and found it very enlightening.

The discussion about engine types seems not relevant to me, because both should reach a much higher rpm at full throttle/no load than the figures you posted here.

baeckmo

10-30-2009, 05:34 AM

Sorry, conflicting info on rotation. Have confirmed from ZF that 2.63 RIGHT HAND is correct! So, back to engine checking.

With a correct engine setting, you should have a good compromize with a RH 18" * 12", giving ~3600 rpm on the engine.

sailingmonica

10-30-2009, 01:14 PM

CDK, could you please provide more info related to the rpm-to-sound program, such as where would it be available?

Baeckmo, thank you for checking with ZF, I could see the point you made initially that it would be easy for an amateur to connect the gear box backwards. In all honesty, the very first time and the very first transmission we actually connected backwards, but we learned from the screw-up and knew better next time.

If I can get my hands on the program mentioned by CDK I will check my rpm's, but can only do that next spring.

So, I will take your advice and order the 18x12 and see what happends. I can always have the pitch adjusted if need be.

I would like to thank all of you for your help and patience. None of us can know as much as all of us. Hugs to all of you. Be safe, healthy and happy!

Monica

baeckmo

10-30-2009, 01:54 PM

Ok, so you are wrapping her up for winter now? Right now it feels good to be at the warm side of the Gulf stream,lat ~58 deg N...

Just to cure my curiosity, have you checked the banjo bolt connecting the injection pump to the fuel return line? If correct, it should have a set of tiiiiiny little holes, like 0.4 mm dia. Anything bigger will cause too low pressure in the pump housing. There are two important consequenses:

1/ The injection timing is controlled directly from the variation in pressure as a function of rotational speed.

2/ If the housing pressure is too low, the filling of the injection pumping cylinder intself will be reduced, due to cavitation in the inlet slot. This phenomenon "overrides" the centrifugal governor and will reduce both max rpms under load and max no-load rpms.

Some pumps have nearly externally identical banjo's for inlet and return, guess what has been observed on DIY conversions..............? The inlet is the one with biiiig holes!

All the best to you, good luck!

CDK

10-30-2009, 02:38 PM

CDK, could you please provide more info related to the rpm-to-sound program, such as where would it be available?

Monica

The answer is here: http://www.boatdesign.net/forums/onboard-electronics-controls/tachometer-diesel-engines-28134-2.html#post291932

Carefully read the instructions; only with the proper range set do you obtain the exact rpm.

Good luck!

apex1

10-30-2009, 02:56 PM

And the link:

http://www.tunelab-world.com/rpmsound.html

good luck

sailingmonica

10-30-2009, 03:23 PM

All right, got to admit I changed the pump. When we were down South the old one (the one that came with the engine) started to leak, apparently due to the ethanol in diesel, which causes the gaskets to dry and shrink. So we ordered a replacement from the only place that had one available, namely partsplaceinc.com in Michigan. Of course, it too was a rebuilt.

We connected the in and out the same way they were connected before. I have good close ups but they exceed the limit for jpeg attachments. I don't know if you can see on the one I attached previously (taken with the cell phone as less pixels), but the fuel inlet is the one at the bottom of the picture going upwards, the one where the hose has mesh inside. The fuel return is the one that goes from the top of pump at the back to the right and has a spare clamp dangling from it. I will look for the big/tiny holes nonetheless, just in case.

And yes, MONICA is out for the winter. They only haul you out till mid November, but I wouldn't want to do it that late, too darn cold.

baeckmo

10-30-2009, 06:22 PM

Hear,hear, hear...... Hope I may live to hear the end of this tale!! (And that you care to tell me!)

Frosty

10-30-2009, 08:58 PM

A power boat needs to go fast , it needs max HP and a perfect matched prop.

You don't need that. you need leasurley economy with low noise.

42 feet,-- 6 knots at 3000 RPM with 53HP. you will be lucky if all your prop changing will get you 1 knot more.

You are pretty close where you are, I would not set up a cruising yacht for max RPM.

sailingmonica

10-31-2009, 11:02 AM

Frosty, I am not looking for speed. I want good docking maneuvrability (which I have now) and I want to be able to take off without spinning before picking some speed. I am concerned that if I have no thrust for take-off I may not be able to fight currents or strong winds on the bow. Any suggestions are welcomed.

Baeckmo, I will keep you posted. I am not one to turn my back once I got what I wanted.

CDK, thank you for the info.

Apex1, will keep in touch.

sailingmonica

11-19-2009, 12:18 PM

In the spirit of the promise to keep you updated, and as humbled as I can possibly be, I have to tell you what I did.

I stumbled upon a 1994 Volkswagen Golf Diesel engine, 1.9, non-computerized, and I bought it. It is turbo, but I will remove that, which should leave me with something like 70 Hp at 4,200 RPM.

That brings me back to square one. Now, I cannot ask you to go through the exercise of calculating a new propeller for me, because you've done it already on the 1.6 engine. I just wanted to let you know what happened since the last post.

But, of course, I will welcome any advice.

baeckmo

11-19-2009, 01:01 PM

CDK

11-19-2009, 01:20 PM

Hi again, nice to have a sign of life! But I must oppose here: don't mess with the turbo, let it stay in place!!! You have a far better engine with it than without, even if you won't use all the horses in the herd. It gives you (us?) more freedom to select a propeller that suits the boat.

Words of wisdom Baeckmo! The tiny, narrow intake manifold will leave the engine short of breath if the turbocharger is removed.
But I'm afraid it cannot stay where it is now because the wet exhaust manifold will be in the way. I think Monica has to read the whole Marinizing VW turbo-diesel thread........

sailingmonica

11-19-2009, 01:39 PM

Oh-oh!

apex1

11-19-2009, 01:47 PM

Fully concur! Leave the turbo where it is! As one positive effect it saves a few drops of fuel, even at lower power.

edit:

I meant Baeckmos comment! Did not know about Cornelis argument.

sailingmonica

11-19-2009, 01:56 PM

Sorry, my last post was lacking brain matter.

Yes, CDK, the issue of the wet exhaust was the reason I mentioned removing the turbo. There is more head scratching needed on my part.

sailingmonica

11-20-2009, 01:41 PM

What if I remove the turbo and I replace the smaller intake manifold with one from a non-turbo to allow the engine to breathe properly? Then I have no need to reposition the wet exhaust manifold and I still have 70 Hp available to me.

And does the turbo actually save fuel? I thought, based purely on logic, that if the turbo is giving the engine more power and anything that gives more power uses more fuel, then the turbo burns more, not less.

apex1

11-20-2009, 01:51 PM

And does the turbo actually save fuel? I thought, based purely on logic, that if the turbo is giving the engine more power and anything that gives more power uses more fuel, then the turbo burns more, not less.

Specific consumption Monica! And there the better "aspiration" has a advantage.

Regards
Richard

marshmat

11-20-2009, 01:54 PM

A turbocharger's role is to cram more air into the engine than it would be able to take in at ambient pressure, thus allowing it to burn more fuel and produce more power on each stroke.

Generally speaking, any sort of forced induction device will increase cylinder pressures, which usually has the effect of improving efficiency (reducing specific fuel consumption).

However, the optimum operating point will also change, so it is quite possible that a turbocharged engine, if run underloaded, may be thirstier than its naturally aspirated twin would be at the same load. (The more sophisticated multi-turbo, variable geometry turbo, variable boost, etc. setups tend to alleviate this drawback.) The only way to know is to compare the 'fuel maps' or 'performance maps' for the engine in both turbo and natural configurations.