I'm looking for a liquid cooled alternative to an air-cooled VW engine for a forced induction non-automotive project. The VW engine weighs about 220 lb and the replacement engine should weigh no more than 250 lb including coolant/oil/etc. in the block but excluding the radiator.

I've been able to get an engine weight for a Subaru EA81 and it seems to be pushing the 250 lb limit a bit, but I have not been able to find a documented engine weight on either of these guys:

Daihatsu 1 liter, found in the Charade.

Suzuki 1.3 liter, found in the Samurai.

If anybody knows the weight of these engines or has an alternative engine suggestion I would be very grateful if you could post a reply.

Briggs has a Daihatsu manufactured 1 liter industrial engine that would work well weight wise, but what literature Briggs has made available limits the top RPM to 3750 and it is expensive. This could still work if it's just a matter of removing a mechanical governor to no ill effect, so if anybody knows anything about this engine that would be very helpful as well...

http://www.vanguardengines.com/vanguard-engines/detail/index.cfm?range=31%20Gross%20HP*%20Gas&series=Three%20Cylinder%20Liquid%20Cooled

TIA

geo metro 3 cylinder?

yeah, the geo 3 cyl might work. Any idea what it weighs?

nope, but found this!

http://gtkgeo.50megs.com/custom.html

quote:

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The 3 Cylinder Engine
Engine Material: Aluminum Block/Head/Intake
Engine Weight: 134.5 lbs. (fully assembled)
Engine Type: In-line SOHC 3 cylinder (RPO LP2)
Displacement(cu. in.): 1.0L (61)
Bore/Stroke(in.): 2.91 x 3.03
Horsepower @ RPM: 49 @ 4,700 (XFi)
Horsepower @ RPM: 55 @ 5,700 (Base and LSi)
Torque(lb/ft) @ RPM: 58 @ 3,300 (All Models)
Compression Ratio: 9.5:1
Fuel Induction: Electronic Fuel Injection
Exhaust System: Single
Ignition System: Electronic High Energy
Alternator Rating: 55 amp (50 amp convertible)
Battery Rating: 400 cca
Cooling Capacity: 4.1 qts (4.2 with automatic)
Fuel Capacity: 10.6 gal.

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155#? From this forum...

http://www.homebuiltairplanes.com/forums/sale/4695-geo-metro-3cylinder-engine-w-redrive.html]

1st post. If you are looking for small engines, look in "home built airplanes". Seems like that community is getting them and suping them up for light powerplants.

~egon

[This message has been edited by Dr. Doctor (edited 4/28/2010 9:01a).]

Thanks! It would seem that my google searching "skills" appear to be sorely lacking. Found a couple of aircraft conversion sites but could not seem to find an engine weight for whatever reason...

Have you thought about getting a motorcycle engine?

What are your power requirements?

What's your project?

Have you looked into the mazda wankels?

quote:

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Have you looked into the mazda wankels?

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Interesting suggestion.

quote:

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What's your project?

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I'm building an airboat. Trying to get 65-70 HP with a turbocharged LPG fuel setup. Weight limited per the plans. No real power limitations but limited to a 66" diameter propeller.

I've done the math and it is achievable with the Briggs/Daihatsu/Vanguard engine & an intercooled turbo, but the best price I've found is $3400 for the engine. Already have the turbo.

The airboat plans call for an air cooled VW engine, but it is mechanically difficult to install a reduction drive and still provide adequate cooling. The aircraft conversions rely on the ambient air flow which I won't have with boat speeds and a pusher arrangement. Without the reduction drive the VW just can't develop enough HP at the max propeller speeds (~2800 RPM) to provide enough thrust. No forced induction because of the cooling issues.

Air cooled Corvair engine would work well, except it is too heavy. Liquid cooled engines are generally heavier on a per HP basis, but they have much more efficient cooling. The weight issue has to do with center of gravity. Can't have too much weight with the engine sitting high in the boat without getting top heavy, so the radiator will be remotely located below the C.O.G. & behind the prop. Plenty of airflow for the radiator.

Despite their power/weight advantages, Wankel engines aren't used much by the aircraft conversion crowd. Not sure why, but I seem to remember reading that reliability is the main issue. I'm obviously not going to fall from the sky with an engine failure, but I might get stranded on a remote stretch of river. And I know absolutely nothing about modifying or maintaining a rotary engine.

Motorcycle engines depend on higher RPM's to develop their HP, as do traditional aircraft engines. I've located reasonably priced reduction belt drives with 2:1, 1.69:1, and 1.65:1 ratios. If I used the higher RPM engines I would have to design & build my own or purchase an aircraft drive ($$$$).

Sorry for the long post, but you did ask

Thoughts?

the dune buggy guys have really perfected turboing vw's, and they've overcome the ehat issue

also the subaru's would be an advantage because there flat, thus lower cg.

VW engine dune buggies and sand rails take the power off the flywheel side of the crankshaft through a transmission as it was designed. The aircraft style reduction drives all use the opposite crank side pulley and ditch the generator and cooling fan apparatus. A flywheel side reduction drive could theoretically be rigged up, but it would be a challenge to mount and you would likely lose the starter. It's easy enough to hand crank start an airplane, but you would be wading to do it in a launched airboat.

Here are a couple of links/images that (hopefully) illustrate what I'm talking about:

http://www.glen-l.com/designs/special/airboat-notes.html




http://www.greatplainsas.com/screddr.html



Note the lack of a cooling apparatus with the reduction drive (above) like you would find in a stock VW shown below:




Thanks again for all the replies

quote:

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Motorcycle engines depend on higher RPM's to develop their HP, as do traditional aircraft engines.

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Not quite. A traditional aircraft engine turns pretty darn slow. 2400RPM would really be spinning fast for a plane. Has to do with prop efficiency and keeping the prop tips from going supersonic and losing lift (thrust)

You may be thinking of the Rotax or auto-to-plane conversions which do spin up fast and use a gear box or belt drive to keep prop rpm low.

quote:

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Motorcycle engines depend on higher RPM's to develop their HP, as do traditional aircraft engines. I've located reasonably priced reduction belt drives with 2:1, 1.69:1, and 1.65:1 ratios.

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You might be surprised by the lower rpm power of some motorcycle engines, particularly for engines in cruisers and tourers. Below is the Yamaha FJR1300's hp & torque curves. You can see that the torque is pretty dang flat through the whole power band. Yeah, you have to kick it up north of 7000 rpms if you want to see the full 145+ hp, but if you use a 2:1 reduction, you'll have ~110hp/80ft-lbs available at 5600rpms (you mentioned 2800rpm for the propeller). With a 1.65:1 reduction, you'll have ~80hp/70ft-lbs at 4600 rpms.

I don't know what it weighs, but given that the whole bike has a dry weight of 580lbs, and it's a full size sport-tourer with full fairing, windshield, hard bags, etc. I bet the engine alone comes in well under 250.



[This message has been edited by F W ag 01 (edited 4/29/2010 12:07a).]

The triumph Speed Triple engine is a very torquey triple. You can buy the entire used 955cc motorcycle for $2K and use the engine. Try to find one in a front end collision and you might be under $1000. The 1050cc model has an even higher rated torque, but being a later model, might be more expensive.

The engines typically reach max torque around 3000 RPM.

BTW, I saw an airboat near Victoria back in the early 80's with a Pratt and Whitney Radial 7 cylinder. It looked really scary.

[This message has been edited by Yuccadoo (edited 4/29/2010 10:38p).]