Turbo Charging Gas Engines ?

[brian eiland]

..thought this might be of interest to those that have gas engines on board

"In addition to employing lightweight design, hybrid drives, and optimized injection systems, automotive industry development engineers are designing smaller internal combustion engines in order to achieve their ambitious targets of significant reductions in vehicle fuel consumption, and thus of carbon dioxide (CO2) emissions, in the next few years. Early market analysis by Continental led to the conclusion that almost all European and Asian engine manufacturers were focusing on developing small turbocharged gasoline engines, and that there were excellent opportunities for growth in this segment in the next few years"

...more HERE (http://www.designfax.net/news/stories/feature-4.asp#)

[daiquiri]

Ehm... Maybe I've missed the point, but - what's the news there?
It's been at least 7-8 yrs by now that small turbocharged diesels (around 1.4 liters) are being used in automotive industry, and even 1.2 liters TDs are being introduced lately.

[brian eiland]

Ehm... Maybe I've missed the point, but - what's the news there?
It's been at least 7-8 yrs by now that small turbocharged diesels
Gas engines, not just diesel

[rasorinc]

All Subaru engines in their cars have been turbocharged for years.

[apex1]

The BMW TI models to mention just one Brand. More than 40 years ago.

[rcig]

I turboed twin 165 mercruisers (inline 6 cyl). saw a nice increase in power but ran into reliability problems.

[brian eiland]

A lot of gas engines are not built to handle the extra forces involved in turbo, or super charging

[Jimbo1490]

All Subaru engines in their cars have been turbocharged for years.

Maybe some are. My '04 Forester is not turbocharged.

Jimbo

[Jimbo1490]

A lot of gas engines are not built to handle the extra forces involved in turbo, or super charging

I guess you never got into the whole Buick GN scene, back when that was hot. Not to mention Porsche 911/930.

Jimbo

[Ike]

Automotive Gas and Diesel engines have been turbocharged for at least ten years and the trend started at least 25 years ago. Actually, the latest trend is back to supercharging. If Ford is just starting to turbocharge their engines then they are way behind the curve.

[Frosty]

Supercharged Bentley 1930's.

Spitfire during 2nd world war.

[thudpucker]

I turboed twin 165 mercruisers (inline 6 cyl). saw a nice increase in power but ran into reliability problems.

Are you talking about the GM 6 cylinders?
Did you get too much boost? How did you know what the boost was? Did you have a guage?
The reason I'm curious is because its a coming thing for older engines. It should be reliable if the boost is kept down around 2-5%.

I had a Mitsubishi 2.5 Turbo and my friend had an Izusi 2.5 Non-turbo. My engine would pull his down the road backwards. Got better milage and started better too.
I like the Turbo Idea.:) Especially for hi-speed cruising at a fixed Rpm.

[apex1]

A lot of gas engines are not built to handle the extra forces involved in turbo, or super charging

Sorry brian, thats not true. Every ic engine can handle that, no matter diesel or gas. The question is to which extend charging (compressor or exhaust turbo) is sensible before a noticeable decrease of lifespan takes effect. Bentley (Bentley Blower), Mercedes, Audi, all used compressor charging during the late 20ies and 30ies.
The early 60ies have seen the introduction of the modern exhaust Turbocharger, mainly KKK and Garret, the 90ies brought the combination of a compressor for the lower rpm range and a turbo for the higher. (Mercedes, VW).

So there is absolutely nothing new in this field.

Regards
Richard

[brian eiland]

A lot of gas engines are not built to handle the extra forces involved in turbo, or super charging

Sorry brian, thats not true. Every ic engine can handle that, no matter diesel or gas.
So I guess there was or is no real need for those 4 bolt mains, custom pistons, extra ring sets, more robust rods, etc in certain 'forced air input engines' :?:

The question is to which extend charging (compressor or exhaust turbo) is sensible before a noticeable decrease of lifespan takes effect
Care to define what this decrease in lifespan might be?? I would say that if its too short a short lifespan, then the 'engine was not properly built to handle the extra forces' !!! That was what I was saying, not all engines are built to live under 'supercharging' for a reasonable lifetime, as they were never intended to be put to that use.

[Cheesy]

So I guess there was or is no real need for those 4 bolt mains, custom pistons, extra ring sets, more robust rods, etc in certain 'forced air input engines' :?:


Care to define what this decrease in lifespan might be?? I would say that if its too short a short lifespan, then the 'engine was not properly built to handle the extra forces' !!! That was what I was saying, not all engines are built to live under 'supercharging' for a reasonable lifetime, as they were never intended to be put to that use.

There are really too many variables to give an answer to that. The most common reason for an engine that has had a turbo fitted to fail is detonation. So basically if you run low enough boost and fuel with high enough octane rating you may not significantly shorten the life of the motor at all.

[pistnbroke]

The point of the original quote is missed ...in an auto the power required in most situations is small so a small engine can provide the power with high economy ..but for those situation that require extra power then the turbo can come in ....if you boost 15psi you in effect double the capacity of the engine....hence small engine economy off boost and big engine power on boost .... 1.2 litre at cruise 2.4 litre for acceleration ...This is not the marine situation where the load at a given speed is constant ..no hills ....

[AmbitiousAmatur]

As long as the wastegate and overall setup is tailored to the engine there should be no major problems. There are turbocharged engines from the 60s and 70s probably still running around like the old Datsun Z cars for instance. Of course, the higher the compression of an engine, the higher quality of fuel required. There is information out there on what must be done if adding aftermarket turbocharging to a naturally aspirated engine. Go with better plugs to ensure ignition at higher pressure. There are other less expensive undertakings which can probably add comparable power to an engine, but turbo is the best option for power along with better fuel economy. Some people online even claimed to have gotten over 150 BHP from a home-brewed turbocharged 50 cc two stroke from a scooter.

[pistnbroke]

Thats 3000 HP per litre I think not .....

[brian eiland]

....if you boost 15psi you in effect double the capacity of the engine....hence small engine economy off boost and big engine power on boost ....
And just try boosting some 'stock, non-turbo' designed engines with a steady diet of 15 psi and watch them come apart in short order.

[rcig]

my boat is powered by 2 inline GM 250 6 clyinder engines. I purchased M&W turbo kits that used RAYJAY turbos. to keep the boost low, under 6 pounds, they took a B comperssor housing and put in a smaller E wheel. It did nothing for the bottom end which was ok, but above 2500 rpm's it really came on strong. At 5200 rpm's it was singing along. With propeller, carb, distributer and exhaust modifications, I picked up about 10 MPH. It was supposed to be up 20-25% in horsepower.

[brian eiland]

Those GM 6 cyl inline engines were good old tough engines. They were built to put out and handle torque. Your boost pressure of 6 lbs is very reasonable, compared to 15 !

Exhaust turbos are notorious for their lack of low end response, and one of the reasons some car manufacturers went back to belt driven superchargers. Boaters on the other hand don't need that low end 'jump-off-the -line' response, so turbos are the better option.

BTW, did you realize that the inherently best naturally balance cylinder configuration is the in-line six arrangement, not 4, not V-8, not V-6. BMW was one car manufacturer that stuck with that arrangement for years. Ford and GM should consider looking back at their good old solid performers as well. Cutting 2 cylinders out of their engines could save manufacturing cost and give them better fuel economy.

[FAST FRED]

Cutting 2 cylinders out of their engines could save manufacturing cost and give them better fuel economy.

Could be fairly EZ to build an I-6 for the coming tiny death reap econoboxes , and a V 12 for the cars that weigh over 1500lbs using all the same components , except the block..

FF

[thudpucker]

Cutting 2 cylinders out of their engines could save manufacturing cost and give them better fuel economy.

Could be fairly EZ to build an I-6 for the coming tiny death reap econoboxes , and a V 12 for the cars that weigh over 1500lbs using all the same components , except the block..

FF

I think GM did that during the 30's. Somewhere I remember Dad telling me about the V-12 that used the Pistons, rods, etc of the Six.
There were lots of strange things done under the hood's of those early cars.

[Jimbo1490]

I think GM did that during the 30's. Somewhere I remember Dad telling me about the V-12 that used the Pistons, rods, etc of the Six.
There were lots of strange things done under the hood's of those early cars.

Why do you think the Chrysler 'Slant 6' exists? It was supposed to be a V-12 for luxury and muscle cars, but the recession of ~1960 put a halt to that plan. So the slant 6 was born instead. As an interesting side note, for technical/logistical reasons, namely, the main and cam bearing oil galleries were on one side of the V-12 block, that is the 'side' of the engine that became the slant 6. Trouble is, that side of the block did not contain an oil gallery for the tappets, so hydraulic tappets were out of the question. So the slant 6 got solid tappets at a time when the whole (American) industry had already made a switch to hydraulic tappets.

Jimbo

[brian eiland]

Ford and GM should consider looking back at their good old solid performers as well. Cutting 2 cylinders out of their engines could save manufacturing cost and give them better fuel economy.
I've often thought Chev could keep its great Suburban vehicle while giving it 25-30 percent better fuel economy....just cut two cylinders out of that big V-8, and put an extra gear or two in the transmission....wala 25-30% better fuel econ.

Then cut out the um-teen different models they have of the same vehicle and save some more manufacturing cost...doesn't take a rocket scientist to figure that out, but certainly appears a lot of highly paid car executives couldn't :rolleyes:

[thudpucker]

Jumbo, I wonder if the Volvo slant six diesel started its life as a V-12?

I considered grafting one of them into my Ford pickup till I drove one. It might as well have been a Slant 3!

[kistinie]

Turbo and compressors are just as old as racing car
MG and others used this much before war
The main problem is that the dynamic volumetric ratio is very wide on a charged engine, turbo or compressor
This will be the origin of the stress as it will make the mixture set up much more difficult as it will depend on variable pressure

The other much more interesting thing is that a turbo is rising efficiency of an engine... I insist on efficiency, not just the power, but the power per litre of fuel is increased
Strange isn't it ?
The 2 LT is not respected as energy to run the turbo is only coming from the engine, so efficiency should go down as power is lost in turbine friction, and a lot, as friction is not linear but exponential with rotation speed.
But no ...efficiency goes up !
This is the important point about the turbo effect...it is always so fun that such an anomaly is accepted without any interrogation ! :D
Maybe it is because turbo are now common item, so it is too late to hide them, but their true real effect is ignored.
Same mistake is not done on much more sensible subject, not spread yet, such as cold fusion, violently rejected.

[thudpucker]

The Exhaust driven Turbo was best used in WWII on the Hi-altitude Re-cip's of the Bombers and Fighter escorts, to provide Combustion Air in the thin air.

Turbos are really better suited to stable Rpm engines. The expanding gasses do provide enough energy to run a pump which provides a little more air than atmospheric pressure.

All those variables you mentioned can be handled with Electronic Fuel injection and all the sensors EFI uses. The SAE are pretty good at getting a lot more out of a Turbo engine without killing the engine.

When you try to get a lot more Rpm out of an older, normally asperated engine, without an Engineers help, is when you start killing good engines.

[blaze_125]

And just try boosting some 'stock, non-turbo' designed engines with a steady diet of 15 psi and watch them come apart in short order.

Of course, cause that's the dummy way of turboing an engine.
If someone wants to push anything higher than 7 or 8 psi(general rule of thumb) there is more involved than just slapping a turbo charger and some pipes. But generaly 7 or 8 psi of boost will greatly improve performance on stock internals. For anything higher, forged internal are recommanded and usually the way to go. But again, 7 or 8 pounds of boost is usually plenty to have fun on a stock NA engine. That much boost can usually improve performance by has much as 75% with crappy tunning. So a motor doing 100hp will usually do easily 175hp on stock internals if you give it enough fuel.

Turbocharging an engine is a science. You can do it right, or you can do it twice.

[Submarine Tom]

I turbo'ed a 1.6L, 1972, stock, rebuilt Datsun 510 4-cyl engine with a Rayjay

turbo which had a "B" housing on it using a 1 1/4 SU carburator many years

ago. I ran a 1 1/2 straight exhaust out the back. It was noisey at idle, but

once the turbine spooled up it was almost quiet. I ran 100/130 av-gas and

reached 14 PSI on a regular basis using a two stage water injection system.

My point is, I was 19 years old and just winging it and it ran for years.

I raced the car and did quite well until we flew off the side of a mountain.

I agree that marine applications are too demanding for "high" pressure

boosting.

[kistinie]

How was this 2 stage water injection done ?

[thudpucker]

I had a conversation with a Physics professor over water injection.
He says the Technology isnt up to the task just yet.

When I lived in Alaska I realized some of what he was talking about.

[Submarine Tom]

thudpucker and kistinie,

There is little technology involved in the water injection I'm referring to.

A little methyl hydrate would solve the Alaska issue.

Two stage in that two intake manifold pressure sensors would activate two

windshield washer bottle/pumps. One at three pounds and the other at

nine. The injectors were low grade bolts drilled out and simply bolted to

the air cleaner cover. They were offset ever so slightly from centre so

the water squirted directly onto the impeller. The first stage jet was

smaller in diameter than the second. In retrospect, a third may not have

been a bad idea but I never expected the self limiting system to develop

so much boost. It all worked so I didn't "fix" it. I didn't hear any

detonation but that doesn't mean it wasn't happening of course. Although,

when I tore the engine down years later, there were no signs of it. The

compression chambers were amazingly clean from all the steam cleaning

they had received.

Again, I agree with the previous post that marine use of turbos isn't nearly

as advantagious with gas engines unless it is a light weight, high

performance boat where weight is an issue. Even then, a turbo diesel

would be a better way to go. More torque and better suited to turbo'ing.

Tom

[brian eiland]

If I remember right when water changes to steam it expands (or tries to) by 17,000 times. So just a little drop of water could make quite a pressure difference in the combustion chamber.

Wasn't there a WWII aircraft that made use of this supercharging method??

[Jimbo1490]

For a while I used the same setup with windshield washer bottles as described above on an '85 GN. Believe it or not I found that the water droplets were eroding the turbo impeller! If you've ever seen what rain does to helicopter main rotor blades (the ones that use Al leading edges, like the Bell 206) then this is not so far fetched. I observed this on two different impellers. There were very good air filters upstream, so no other explanation.

Jimbo

[thudpucker]

Now the thread is getting interesting.
On FLoat plane's the Props suffer badly from water droplets. Like those Choppper blades.
Tom's description of what he did is new to me. I tried to draw it on paper to better understand it. It sure sounds like it worked for him

On that WWII plane using water injection. They tried that in a number of applications. War time engines dont care about water damage. They are expendable. I think just about everything they tried in WWII was never used again except for Exhaust powerd Turbo Charging.

The professor talking to me about water was referring to the chemical damages water did to some parts of a Gasoline combustion engine. This was in the early 60's though, so things may have improved since then.

Steam is so much more powerful than Gas or Oil because it expands so much more. However its not as quick so the guys who really want action dont mess around with steam. However, too much steam in a small combustion chamber could be a bad thing if you let it mature.

If a boat was powerd with an older, long stroke, low combustion engine. That little bit of water in the slow turning engine might just make a noticable difference without killing anything.
Turbo charging one of those old slow luggers might help too, but increasing the Rpm's seems like a crime to me.

Logically thinking, if your going to those lengths to get more power, change engines for a bigger Capacity.

[thudpucker]

Jimbo, what if you injected the water after the Turbo?
Would that would work?

[Jimbo1490]

Yeah it would and did. But then you have to atomize it properly, and there are also potential distribution issues, even injecting right after the turbo. Sending it through the turbo impeller micro atomizes and homogenizes it. Too bad about the erosion, huh?

My next setup used a in-tank EFI style fuel pump to pump the water (at high pressure) through atomizing nozzles downstream of the turbo. Problem solved, but it neccessarily gets much more complex to do one of these setups right.

Jimbo

[thudpucker]

Your right on it. I used to fool around with the porting Bike engines, and oneday I had the chance encounter with an Engineer from HarleyDavidson.

Boy did I learn a lot about induction and the real tricks to 'atomizing' so you present a thoroughly emulsified mix to the compression chamber, and then shape the compressioin chamber so that mix dont re-combine or solidify as it swirls into the chamber and slams into walls of metal and thermal walls from the previous combustion gasses left in the combustion chamber, which are still expanding....They actually have Cameras to get photos and movies of this happening. Amazing eh?

As you can imagine, I was kinda thrilled and overwhelmed at the same time.
One thing that conversation taught me is that a very well funded and equipped R&D lab is an ablolute necessity when your are going for the gusto!!

One of the things he mentioned was not to polish the intake walls. The roughness of the walls helps.
The smoothness actually causes a thick hard layer of static air to develop and stick, slow down, which grows, choking down the size of the tube, and actually inhibits high speed induction. Whodathunkit?

[thudpucker]

Yeah it would and did. But then you have to atomize it properly, and there are also potential distribution issues, even injecting right after the turbo. Sending it through the turbo impeller micro atomizes and homogenizes it. Too bad about the erosion, huh?

My next setup used a in-tank EFI style fuel pump to pump the water (at high pressure) through atomizing nozzles downstream of the turbo. Problem solved, but it neccessarily gets much more complex to do one of these setups right.

Jimbo

The BOSCH Mechanical FI used on the VW Rabbit has a similer product to your idea. As soon as the Induction starts, a switch tied to a flap in the induction port causes a pump to start up and the injectors start spraying under hi pressure. I liked that setup. Simple and it worked good with good Mpg. The only problem was the filters just couldnt keep the fuel clean and plugging the injectors was an expensive problem.
Keep that in mind as you hi-pressure your water spray.

[brian eiland]

For a while I used the same setup with windshield washer bottles as described above on an '85 GN. Believe it or not I found that the water droplets were eroding the turbo impeller! If you've ever seen what rain does to helicopter main rotor blades (the ones that use Al leading edges, like the Bell 206) then this is not so far fetched. I observed this on two different impellers. There were very good air filters upstream, so no other explanation.
Jimbo
I don't think he meant injecting the water into 'turbo impeller'. I wouldn't think that was such a good idea. Besides why do you need the turbo unit when you get the sought after pressure by the water expansion?

[thudpucker]

Brian, I dont know this for certain, but I think the water would never heat up and turn to steam fast enough to be usable if it werent pre-heated before it hit the compression chamber.

We'd need the 212 Degrees long before the water passed the intake port in the head.
Water takes longer to expand than Gasoline. So if it were suddenly heated to 1100 degrees in the compression chamber, it would be expanding rapidly but as it did, it would also be passing out the exhaust port. Too late to help with moving the piston.
The Gasoline piston speed is so much greater than a Steam engine piston speed.

I think we'd want to pass the water spray over a heated electrode so it was nearly steam as it entered the in-flow through the Intake valve.

Without a lab to test this theory, I'd really be guessing in the dark.

[brian eiland]

Plenty of preheat available right at exhaust pipes, particularly for such a small amount of water actually injected..... I would think?

What did those Spitfire aircraft do? I think it was used on them...one of those WWll fighter aircraft?

..one reference
http://blizzard.rwic.und.edu/~nordlie/water_injection/background.html

[brian eiland]

http://www.chuckhawks.com/best_fighter_planes.htm

The final Messerschmitt production variant was the "K," deliveries of which began in September of 1944. The "K" was powered by an 1,800 hp DB 605D engine (2000 hp with methanol-water injection) that gave it a top speed of 452 m.p.h. at 19,685 feet. Best climb rate was a sensational 4,820 ft./min. Armament was two 13mm cowl mounted machine guns and one engine mounted 30mm cannon firing through the propeller boss. Two additional 20mm cannons were mounted beneath the wings in the K-4/R4 variant.



The final major production version of the Mustang was the P-51H. This re-designed model incorporated major improvements, as extensive in scope as those incorporated into the FW 190D or Spitfire Mk. 22.

In the H model, the structure was increased in strength by 10%, to allow higher "g" loads in combat maneuvers. No structural part was left in common with earlier models. Streamlining was improved to increase speed, and stability was increased. A new version of the Packard/Merlin, incorporating water injection, delivered over 2000 hp. These changes resulted in the finest American fighter of the war. Speed was 486 m.p.h. at 30,000 ft. best climb rate was 5,350 ft./min. at 5,000 ft. Service ceiling was 41,600 ft.

[Cheesy]

The water injection was used to prevent detonation

[Jimbo1490]

The water injection was used to prevent detonation


This is exactly right; water serves the same function here as 'power enrichment', that is as an evaporative coolant, nothing more. Methanol is added to recover power lost by injecting water only.

The turbo compresser outlet temp on my GN was approaching 300F, so the water injection helped quite a bit as an evaporative coolant or 'poor man's intercooler'.

Jimbo

[flyinwall]

Supercharged Bentley 1930's.

Spitfire during 2nd world war.


but mercedes had a supercharged 6 litre straight 8 in 1928 apparently it was capable of 100mph

[thudpucker]

Fly,
A Turbo-charger is a pump driven by the exhaust. It's different than a Super-charger, which is an engine driven pump.
The rare air at 20,000 to 40,000 was too little for Combustion engines. A super charger used too much Horse power to make a great difference so they went to the exhaust driven Trubo's to provide power for an Air compressor feeding the cylinders.

At sea level a Super charger works fine and I think I was told it can provide much more compressed air than a turbo charger can.
But its more expensive in terms of the cost of energy.

[flyinwall]

Fly,
A Turbo-charger is a pump driven by the exhaust. It's different than a Super-charger, which is an engine driven pump.
The rare air at 20,000 to 40,000 was too little for Combustion engines. A super charger used too much Horse power to make a great difference so they went to the exhaust driven Trubo's to provide power for an Air compressor feeding the cylinders.

At sea level a Super charger works fine and I think I was told it can provide much more compressed air than a turbo charger can.
But its more expensive in terms of the cost of energy.


no offence but i am not stupid as i have been around supercharged and turbo'd cars for a long time and i was only making a reference to the length of time the auto manufactureres have been using forced induction

[Jimbo1490]

At sea level a Super charger works fine and I think I was told it can provide much more compressed air than a turbo charger can.
But its more expensive in terms of the cost of energy.

There is some truth to this but it is not always spot on. All turbochargers that I know of use a 'dynamic' compressors, always of the centrifugal (rather than axial) kind. These sort of devices are mass-flow devices, in that they are loaded by and perform their work on a certain mass of gas. So as altitude increases and the air becomes rarified, the centrifugal compressor continues to pack in nearly the same amount of air (actually it does fall, but gradually and linearly not exponentially and precipitously) because the dynamic compressor responds to the mass of gas, not volume.

Contrast that with a roots type blower, which is a positive displacement device which performs its work on a certain volume of gas, a volume that contains fewer gas molecules as altitude increases.

But then the supercharges used on all the radial aircraft engines that I know of are also centrifugal dynamic compressors, not roots blowers, so they would continue to be effective at higher altitudes.

But the power required to do the amount of work we are discussing (1500 CFM @ 10-15 PSI for rough calcs) is not trivial; indeed it's not uncommon for there to be 100 HP or more dissipated across the shaft of the turbocharger on a modest sized diesel engine. In a mechanical supercharger installation, this power is subtracted from the output shaft while in the turbo setup, it recovered as waste heat from the exhaust. The small power subtraction due to backpressure on the exhaust side is more than made up by the pumping action on the intake side.

Jimbo

[thudpucker]

Thanks to all of you for the lessons and information.

[brian eiland]

There is some truth to this but it is not always spot on..... Jimbo
Nice explaination Jimbo

[kistinie]

Plenty of preheat available right at exhaust pipes, particularly for such a small amount of water actually injected..... I would think?


You think well, but you think border line... very dangerous for you peace and wallet.
Brian, pre heating water before injecting the vapour is the principle of the Giller Pantone engine, wich is technically great, but politically incorrect.
More generally, talking of water in positive terms, like cold fusion (http://www.scifi.com/sfw/issue151/labnotes.html or http://physicsworld.com/cws/article/print/1258 ), same for over unitary electrolyses, will get into serious business trouble !

The wind of economic success is blowing for oil and coal, not for water and hydrogen
http://www.ecogeek.org/content/view/667/

So unless you are ready to retire, accept a reduction of your income and look at the world with another eye, my advice is, let the water under you boat, never think of it in your engine.
I'm not the inventor of these wicked rules ;-)) ...Sorry for the uncomfortable position i may have put you in. ...but the positive aspect is that i and many others will be your supporter if you consider worth to go deeper in the direction of the study of water as an energy.

May be this will give hope...

All truth passes through three stages:
First, it is ridiculed;
Second, it is violently opposed; and
Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)


Edited...
It seems i have killed the line, maybe we could add a second bis state to the Schopenhauer's theory, that could be called the fear ?

[powerabout]

Supercharged Bentley 1930's.

Spitfire during 2nd world war.
GM diesels before the WWII

[powerabout]

I read an SAE paper on...
Ford tested water injection way back in early 80's on turbo charged Escorts or some small sh*t box to see how long term turbo'ed engine would hold out in the analogue electronics days.
They had water injection and the long term tests showed cylinder damage caused by the constant steam cleaning of the cylinder ( that how you wash oil off parts right) so they shelved it for another day.

PS Turbos work perfectly on aircraft as due to the thin air the turbo revs harder and make up for the less dense air...

How about a 8000 hp drag race motor, the blower absorbs about 400hp..just look at the belt.
The turbo, although an inlet and exhaust restriction, doesnt swallow the power like a belt driven gizmo BUT since there are only about 2 turbo manufacturers these days they are too expensive to use and as GM diesels proved..blowers are very reliable and cheap...

[Cheesy]

I read an SAE paper on...
Ford tested water injection way back in early 80's on turbo charged Escorts or some small sh*t box to see how long term turbo'ed engine would hold out in the analogue electronics days.
They had water injection and the long term tests showed cylinder damage caused by the constant steam cleaning of the cylinder ( that how you wash oil off parts right) so they shelved it for another day.

PS Turbos work perfectly on aircraft as due to the thin air the turbo revs harder and make up for the less dense air...

How about a 8000 hp drag race motor, the blower absorbs about 400hp..just look at the belt.
The turbo, although an inlet and exhaust restriction, doesnt swallow the power like a belt driven gizmo BUT since there are only about 2 turbo manufacturers these days they are too expensive to use and as GM diesels proved..blowers are very reliable and cheap...

I think you will find that they use the Roots type blower because its in the rules, a screw type blower or a turbo would be much more efficient

[Yellowjacket]

Water injection upstream of a centrifugal compressor is a good thing from a performance standpoint. What happens is that the water is evaporated during the compression process and it actually increases the pressure ratio and airflow of the compressor. If you are injecting after the compressor you don't get as much benefit of the water. Yes it does erode the impeller, that is a function of how well atomized the water is as it enters the inlet.

It does not take a huge amount of water to supress detonation, and many folks using water injection actually over inject. Since it is safer (from a detonation standpoint) to do so and it costs little or nothing in performance, that's what happens. I did some research in college with water injection on a variable compression engine and the results were pretty amazing. A little water went a long way.

Injecting hot water is a bad idea. You don't want heat in the water, you want to extract as much heat as you can from the air, since it takes less energy to compress cooler air that results in an improvement in cycle efficiency. Unless you are injecting tons of water, it will all be turned to steam during the combustion process.

As Colin Campbell said in his tome "The Sports Car, Its Design and Performance" and I quote "as a means of finding the weakest link in an engine supercharging has no equal". He was right more than 40 years ago, and is still right today.

Increasing intake pressure increases loads on the pistion, connecting rods and bearings. More importantly, it substantially increases the temperature of the exhaust gases. This is key since stress rupture life of high temperature items such as exhaust valves is cut in half by an increase in temperature of only 25 degrees F. That is, for each 25 degrees increase in exhaust valve temperature the life is cut in half. For 50 degrees increase the life is 1/4 and for 100 degrees increase life drops to 1/16th, and so forth...

Higher exhaust temperatures cause more heat to be conducted into the areas around the exhaust port, causing increased thermally induced material stress (cylinder head crackng) and higher loads on the cooling system.

It is easy to see why turbocharged engines require improved components such as valves and cylinder heads, and forged internals like crankshafts and rods and pistons.

This is why increasing combustion pressures by supercharging or turbocharging a stock engine is a crapshoot since you don't know what kind of margins were designed into the engine unless you have intimate knowledge of the design process and what margins are available in the engine to withstand the additional stress.

Turbocharging works on automotive engines primarily because they spend so little time on boost. In most cases the engine is at high loads for less than 10 seconds at a time. Consequently there isn't time for the parts to reach really high temperatures and the effect of the higher thermal loading isn't realized.

Marine and aviation engines can be run at high percentages of maximum power for prolonged periods of time. Consequently engines run at these power settings have to be much more robust than than the intermittent duty that we see in auto engines. If you are in a "hot rod" boat application where you don't run flat out for a long period, a boosted engine can work, for a while, but you cannot expect a long life or the kind of service that you get from a normally aspirated engine, that's just not realistic.

[Submarine Tom]

Yellowjacket,

Good summary of the thread, although using hot water for water injection wouldn't cause

that big a difference in benefit as the majority of energy consumed is in phase change.

I'm not sure why heating the water came up but why would you in the first place?

When I set up my two injectors, I aimed them very near the centre of the impeller in hopes

that if the stream didn't diffuse from the carburetor induced turbulance, that the near

centre impact wouldn't erode the impeller too badly. It didn't, after years of service.

Although, as you say, the "in use" time on a car engine is minimal. I was only using tiny

windshield washer bottles with low level warning lights. Depending on the amount of "spirited"

driving or actual racing I was doing, they only needed intermittent filling.

As you say, it doesn't take much. Water is a pretty amazing material or substance.

We tend to take it for granted but it's qualities are unique and merits numerous.

Cheers, Tom

[Yellowjacket]

When we did our water injection on a 6 lb/sec airflow gas turbine impeller we first injected the water at the hub. It ran onto the stationary bullet nose and pretty much went in at the blade root. Not much upstream mist at all, but we didn't get as much effect on the compression cycle that we were expecting.

We backed the spray off about a foot from the inlet, and the stream EXPLODED due to the acoustic effect and shocks coming off the blades. I used to have some really cool video of a ball of mist just ahead of the inlet bell. The spray stream exploded and then was totally sucked into the engine inlet. You could see the shocks from the impeller leading edges rotaing in it due to the strobe effects of the 60 hz lights in the test cell. The water rate was about 6% of the total airflow or about .36 pounds per second, or 2.7 gallons per minute.... Which if you think about it is a huge amount of water to pump into any engine.

[powerabout]

how about the cylinder wear due to the steam cleaning effect?

[Submarine Tom]

Interesting,

I never had the opportunity to observe any of that on my turbine.

I did however observe mist clouds of fuel on occasion upstream of the intake on non turbo'ed engines. Incredible.

What kind of RPM's was your turbine turning?

Mine I never measured but read they would run up to 90 - 120 thousand typically.

Tom

[Submarine Tom]

powerabout,

I never saw any evidence of cylinder wear from the steam cleaning, but it did

eliminate carbon build-up completely.