6 replies to this topic

[etoipi]

The other day while I was day dreaming I came up with this engine configuration idea

Take three 3 cylinder 4 stroke engines (good primary balance), put them on a single crankshaft and get a double V formation. With a 40° V between each bank of cylinders, the simplest (and probably only) crankshaft layout, the firing order determines itself and there is a power stroke every 80°s of crankshaft turn.

After I worked this out I did some checking on the internet to find out how good, bad or indifferent this engine layout would be. Despite finding radial 9’s, 2’s, 3’s, 4’s, 5’s, 6, 8, 10,12 and 16 cylinder engine in straight, V & W and boxer configurations, I did not find any information on a double V 9 cylinder engine.

I see the possible pros & cons of this engine as follows
Pros
Good torque
Good balance
Shorter & narrower than a V8
Potential for racing or production

Cons
High-ish centre of gravity
Feeding the fuel and air to the cylinders (particularly the middle bank) may be awkward
How to do the exhaust pipes worries me
Weight
Fuel consumption
Cooling the middle cylinder

While I have the conceptual knowledge, I do not have the practical mechanical knowledge to know how well this engine would work.

Is there anyone out there who can shed some light on the possibilities of this configuration. (Or better still is there someone or some organization out there that could build one for interest sake). Would this engine work? What are the real pros and cons? How would a 2.4 litre double V 9 stack up against this year’s 2.4 litre V8 in F1? Could a version of this engine be made for a motorcycle?

Comments would be appreciated…..

[vvillium3]

check this out...

http://www.atomracing.se/6M.html

Jason

[rhm]

Packaging is always the main reason not to use a true 3-bank engine. With cross-flow heads there has to be one place where exhaust have intake come close together. It's not impossible to make it work, but it's not neat. It's also likely that a V8 of the same configuration could be made lighter than that W9 so unless you needed a short engine (in which case Volkswagen's VR engine technology is a better bet), it's just not a good idea.

[Oho]

Originally posted by rhm
Packaging is always the main reason not to use a true 3-bank engine. With cross-flow heads there has to be one place where exhaust have intake come close together. It's not impossible to make it work, but it's not neat. It's also likely that a V8 of the same configuration could be made lighter than that W9 so unless you needed a short engine (in which case Volkswagen's VR engine technology is a better bet), it's just not a good idea.

To the best of my knowledge VW has built W engines with VR technology, if I am not entirely mistaken they have/had Passat with W8 and Phaeton with W12 both built with two narrow angle VR blocks in V arrangement.

[roadie]

Originally posted by vvillium3
check this out...

http://www.atomracing.se/6M.html

Jason

That looks really interesting, thanks for the link:)

[rhm]

Originally posted by Oho


To the best of my knowledge VW has built W engines with VR technology, if I am not entirely mistaken they have/had Passat with W8 and Phaeton with W12 both built with two narrow angle VR blocks in V arrangement.

That's sort-of what I meant. The VR is really a misnomber in that it's not really a V engine at all. A VR6 for example could be considered to be a very narrow angle V6, but really it's more like a straight 6 with odd and even cylinders offset slightly to allow them to be placed closer together.

Volkswagen's 'W' engines really just mean that they are two VR engines one a common crank. So like a V8 is two straight 4 engines, the W16 used in the Veyron is two VR8 engines. If you considered a VR engine to be a kind of V engine then you'd have to consider the W16 to be a *four* bank engine, not the three-bank design that this thread referrs to. Personally I think the 'W' nomenclature is confusing in both senses which is why it makes more sense to referr to these unusual configurations by the number of banks and the makeup of each bank as if it was a standalone engine.

[Greg Locock]

Just a words of advice. An I3 engine has good rotational balance, so far as force goes, but there is always a net rocking couple about the axis perpendicular to the crank and cylinder axes.

This makes a fair old thump.

Having said that, Daihatsu had the knack of mounting their engine effectively to isolate this. We certainly didn't when I worked on the original K engine prototype at Austin Rover.

Your W9 will also suffer from this to some extent.