older volvo-pentas- MD27 89hp vs AQD32A 106hp

Hi Folks,

Realizing that maintenance, proper use/not idling for hours and hours, and other factors strongly influence the lifespan of older diesels - What are the reputations of these two particular models? (Both Volvo-Pentas)

Technical data

Engine MD27

Production period 1963-1966

Operation 4-stroke

Cylinder configuration 6

Bore (mm) 85

Stroke (mm) 80

Compression ratio 21:1

Displacement (litres) 2.72

Power (hp) 83

Max engine speed (rpm) 4500


vs:


Technical data (would be inboard - no strern drive)

Engine AQD32A

Production period 1969-1977

Operation 4-stroke

Cylinder configuration 6

Bore (mm) 90

Stroke (mm) 83

Compression ratio 22.1:1

Displacement (litres) 3.17

Power (hp) 106

Max engine speed (rpm) 4000

 

First question is who built the engines?

Just because there is a Volvo name plate and marinizing on the engine does not mean Volvo built the block for marine service..

The donor car or truck source may give a good idea of how good the engine ever was.

Those made for only a few years were discontinued for a reason.

 

The smaller one, MD27 specs say it was based on the "well known" Indenor/Peugot diesel engines.
The othe rdoes not say.

 

more engine and gear choices - help please!

Still currently considering a couple of engine/ transmission choices for aluminum boat build - have gotten a bit of feedback but wondered if I could get more advice - adding Cummins to list.
May have mentioned (in a prop post) before - a guy on Glen L site built this design 25' (I will likley do 23') - he used Mercruiser 3.0 inboard (around 130hp gas) and 2:1 reduction, 16" prop and gets about 20mph with no keel or skeg.

Considering:

1. Older but good condition marine straight 6 cyl Volvo-penta 96 hp diesel, with 1.65:1 reduction gear - but about an extra 7 hour drive each way to pick up.

2. Cummins 4BT 4 cyl turbo diesel (130hp) marine with 1:1 reduction - close to home

3. Older volvo-penta straight 6 cyl 110 hp diesel, no trannie but can get 2:1 velvet drive that should bolt right up as they came with these- although this one had previous saildrive or I/O leg.
not lcoal but may be able to get someone to bring it t ome for a few hundred $ after friend checks it out for me.

4. 1986 Nissan S25 2.5L diesel (70hp n/a non turbo)(out of truck) would use Velvet Drive 2:1 with it... cheap, cheap would take chance on it, comes with spare parts engine and I would likely run keel cooling as non-marinized.

Also,
How much do you think a small keel or the larger regular inboard keel would slow the boat down or affect it any other way???

 

Should mention - I know I am considering engines from 70hp - 130hp, but the reason is that I am looking at good value engines and will be happy with performance based on how big of an engine I get - ie I don't have a need to go 20kts, and will be happy with 15kts, if I go with a smaller, good value engine. Or will be gappy doing 20 something knots with the Cummins, if possible.

Here are the preformance #s from the boat plans. I will keep it light, with only CC, not a cabin as in design.

6 knots 10 SHP
9 knots 25 SHP
13 knots 40 SHP
18 knots 70 SHP
22 knots 105 SHP
27 knots (*) 150 SHP
31 knots (*) 200 SHP
(*) Attempting to obtain these speeds with the Inboard Version, due to the deep skeg, may cause excessive fuel consumption and may not be practical.

A local builder of the aluminum version is running at 40 mph with a 200 hp outboard.



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i am pretty sure the aq32 was a renault engine, in aus they have a bad rep. last one i saw got pulled out and thrown in dump.

 

Thanks! I could not find on the Volvo-penta pagem what engine that model it was based on.
Leaning towards Cummins 4BT. A guy has one in same model boat and is happy with performance.

 

the 4bt is a nice engine

 

If it was I- 4BT.
Cheap to buy,rebuild,cheap parts are everywhere and it'll last for thousands and thousands of hours/decades with care

 

Unfortunately, the guy selling the 4BT is holding it for 2 weeks for a distant buyer, who said he was coming to get it. If the guy doesn't show, he will let me know, and I will grab it.
Otherwise, will keep an eye out for 4BTS for sale, even if they are marine versions. I read that are some differences in cam profile, fuel delivery, and of course no heat exchanger- but, as I can do keel/ hull cooling on alumium boat and dry exhaust, or tig wled up a custom echasut elbow, I will consider the cheaper "road" version as well.

Thanks for all of the input!

 

missed out on that Cummins 4BT. Found another, but would need to sell 2.57:1 gear and buy something like a 1.2: or 1.5:1 gear, to use with a 16" prop, according to an on-like prop calculator, and the experience of someone with a 4BT in same boat model. Will try to look at it in net few days.

In meantime, guy reduced price on Volvo-penta AqD32A and contrary to what one member thought here, it looks like it is based on the Indenor / \peugot XDP 6-90 and not a Renault, from what I found on net.
How does that affect people\s opinions on reliability, etc?

 

specs on AQD32A are same as MD32, but the MD32 came with inboard gear and AQD32A cam with a stern drive (270) which this one does not have, so I would likely use a Velvet Drive 2:1 with that engine and 16" prop.
Both are based on Indenor XDP 6-90

 

Don't waste energy on the old Volvo (Peugeot) engines, they are indirect injection engines and as such pretty thirsty. You will find yourself in trouble with heat exchangers and oil coolers etc. The stuff is outdated and there is a reason they are for sale!

The Cummins 4 cylinder BT is a good engine, you'll have no problems with parts and there is marine stuff available all over if you have to "marinize" an industrial engine. Many (all?) versions have an integrated oil cooler, which makes piping layout easy f.i..

 

thanks for advice. Likely going to look at the Cummins tomorrow.

 

Thanks for all advice!
Bought a Cummins 4BT today. Have to sell the 2.91:1 72C model 10-18-012 and look fpor a 1.2:1 or maybe 1.5:1 or even 1:1 as max size prop I can run is 16".
Also have to see 23 x 26 left hand prop 4 blade, looking for 16" 3 or 4 blade