VW's 2.3L oval-piston diesel

[WABIT]

VW's 2.3L oval-piston diesel I just came across this on Ti Kan's Audi site... in 1990, VW developed a 2.3-liter 4-cylinder diesel engine with oval pistons (well, actually they're elliptical, not oval):



Comparison to a standard 1.6L diesel block:


The bore was 99.49 mm in the long direction, and 76.5 mm (same as the 1.6L diesel) in the short direction. The crank was the same as the 1.9L diesel. The exact displacement was 2343 cc, with 57 kw (76 HP) and 165 Nm (122 lb-ft) torque. No turbo. The pistons were developed by Mahle, and the engine was used in several VW test cars, but obviously never put into production. It was written about in 1990 in Germany's "Auto Motor und Sport" magazine, if anyone cares to look it up and translate.

[GoLfMan]

thats pretty cool!

Honda mucked around with oval pistoned race bikes back in the 70's and 80's Cool concept

[craigy]

thats pretty cool!

Honda mucked around with oval pistoned race bikes back in the 70's and 80's Cool concept

Yes, but the hondas were designed to get around a ban on more than 4 cylinders and the pistons were double the size with twin conrods and each combustion chamber had 8 valves so the V4s were effectively a V8. It looks like VW was trying for a capacity increase without increasing the length of the block.

[GoLfMan]

Yes, but the hondas were designed to get around a ban on more than 4 cylinders and the pistons were double the size with twin conrods and each combustion chamber had 8 valves so the V4s were effectively a V8. It looks like VW was trying for a capacity increase without increasing the length of the block.

thats it!

Both very different of course, but still both are very interesting engine concepts. I wonder why the oval pistoned VW didnt make it to production. The Honda's had ALOT of reliability issues unfortunately

[Jarred]

would it be due to excess piston movement because of the elongated shape?

[Ben_GTI]

would it be due to excess piston movement because of the elongated shape?

I would have thought it would be less...... for a variety of complicated reasons... torque, distance, force, impulse..... but yea cbf typing an explanation.

[gldgti]

oval pistoned diesels have been done a few times - there are a few production truck engines with oval pistons/cylinders. The main advantage as has been pointed out - compact over the block length for capacity. if you think about it, there is an inherent disadvantage in more parasitic losses due to friction per cc of capacity, because the circumference/area ratio is less than ideal (its not a circle ).

I would guess that if vw developed this they were thinking about alternatives to the 5cyl diesel engine and testing out ideas (probably with the transporter in mind more than anything). Either way, VW wont go into production unless it makes a lot of sense to do so - and if you think about it, this engine would need all kinds of different hardware compared with its sisters (note that vw diesels have a HUGE parts commonality).

interesting nonetheless - THANKS!