Twin engined cars.

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Discussion

Mr Dave

Original Poster:

3,233 posts

194 months

Friday 2nd July 2010
quotequote all
OK I am thick.

Now we have that out of the way how do you work out how much power a car with two engines has.

Im meaning like the homebrew ones where say a corsa has a redtop in the front and another in the back. for example http://www.mig-welding.co.uk/forum/showthread.php?...

I just cant get my head around how powerful they are.

For example if each engine was 100bhp do you end up with a car that has the performance of a 200bhp car? How does each engine not do the same work at the same speed if that makes sense? Is the power somewhere in between?


s3fella

10,524 posts

186 months

Friday 2nd July 2010
quotequote all
2 100hp engines would indeed be 200hp, but there is the extra weight of the second motor/ gearbox to consider, as well as double the transmission losses of single motor. So in your eg it would be about the same as say 175-185hp fwd I'd think.

Good traction though with 4wd!

Welshbeef

49,633 posts

197 months

Friday 2nd July 2010
quotequote all
Expensive to do, very small resale market & if it were that good in unlimited class racing you would see it being used... sadly that is not the case for a very good reason.

Trying to match both engines together - the added complexity more to go wrong.

OMNIO

1,256 posts

165 months

Friday 2nd July 2010
quotequote all
I've read about twin engine conversions.

If you get it right the results can be great but its easy to get it wrong and from what i can gather it's a huge feat of engineering.

I think i saw in Max Power about 4 or 5 years ago a Mk 1 Golf with 2 audi a3 engines in it.

If i remember right they were having problems getting the engines running at the same time and speed and producing the same power at the same time, as if one engine is more powerful than the other the less powerful engine slows it down.... something along those lines and was so complex seeing the gearbox it made my head hurt!

Seen a few minis with twin R1 engines and they go like the clappers! would love to do a project like that biggrin

ManOpener

12,467 posts

168 months

Friday 2nd July 2010
quotequote all
It's quite a common occurrence in demo cars and the like, though besides the MTM Bimoto and various Z-Cars minis I can't think of anyone whose used them competitively. Dubworks built a nigh- on 700bhp twin engined Mk3 Golf with a VR6 Turbo in either end, was brutally fast in a straight line but not great around the corners. Twin 1.8T engined Lupos have been built before, as has twin VR6 non-turbo Mk1s.

Other comments about linking engines together and additional weight are true, but most twin engine setups only link the engines via the throttle cable, which means less to go wrong.

Edited by ManOpener on Friday 2nd July 16:57

Ozzie Osmond

21,189 posts

245 months

Friday 2nd July 2010
quotequote all
"Twin-engined" really has little meaning. If you look at a V8 is it one engine or two engines? Sure, they share a crankshaft but that's not much different from sharing the same gearbox.

Also an 8-cylinder with a flat-plane crank is essentially two 4-cylinder engines working at the same time - again sharing the crank.

MarJay

2,173 posts

174 months

Friday 2nd July 2010
quotequote all
Ozzie Osmond said:
"Twin-engined" really has little meaning. If you look at a V8 is it one engine or two engines? Sure, they share a crankshaft but that's not much different from sharing the same gearbox.

Also an 8-cylinder with a flat-plane crank is essentially two 4-cylinder engines working at the same time - again sharing the crank.
Except V8's are road legal, whereas twin engined cars are not IIRC.

Streetrod

6,468 posts

205 months

Friday 2nd July 2010
quotequote all
This has to be my fave twin engined car:




balls-out

3,586 posts

230 months

Friday 2nd July 2010
quotequote all
Ozzie Osmond said:
"Twin-engined" really has little meaning. If you look at a V8 is it one engine or two engines? Sure, they share a crankshaft but that's not much different from sharing the same gearbox.

Also an 8-cylinder with a flat-plane crank is essentially two 4-cylinder engines working at the same time - again sharing the crank.
I don't really see that. There are a whole load of differences between a V8 and a twiny.
Anyway Way cool to have 2 engines - thats double a Bugatti Veyron!

Ozzie Osmond

21,189 posts

245 months

Friday 2nd July 2010
quotequote all
....typically found on very fast go-karts.

balls-out

3,586 posts

230 months

Friday 2nd July 2010
quotequote all
Ah. many years before most tried the 'bung a bike engine in' approach was Franco "what a nutter" Sbarro, who gave us this twin engined... err.. car. 2 z1300 6 cylinder motors making a straight 12.



Franco - I salute you!

Although he did have his bad days too.



Edited by balls-out on Friday 2nd July 17:31

SilverPhantom

33 posts

178 months

Friday 2nd July 2010
quotequote all
Good article here about VWs attempt, I remember seeing it at the VW factory, dont know where they ended up. Anyone know?

http://www.driversfound.com/scirocco/history/bimot...

Fort Jefferson

8,237 posts

221 months

Friday 2nd July 2010
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This twin engined Mini was in the car park at Curborough, a few weeks ago.

shirt

22,508 posts

200 months

Friday 2nd July 2010
quotequote all
Streetrod said:
cockwomble & 'friend' in the blue oystermobile?

supersingle

3,205 posts

218 months

Friday 2nd July 2010
quotequote all
MarJay said:
Except V8's are road legal, whereas twin engined cars are not IIRC.
Please don't make stuff up on ph. You'll get caught out.

Steve in Stoke

6,374 posts

183 months

Friday 2nd July 2010
quotequote all
I remember seeing this beastie on Fifth Gear going for the 0-60 record - http://www.tigerracing.com/z100.php

IIRc it had some complex twin gearbox situation that was a work of genius!

ETA - 5th Gear feature on twin-engined cars here - http://www.youtube.com/watch?v=SGq7-cMw5Ws
and 0-60 feature here - http://www.youtube.com/watch?v=phQfA5-DL1I

Edited by Steve in Stoke on Friday 2nd July 18:37

balls-out

3,586 posts

230 months

Friday 2nd July 2010
quotequote all
supersingle said:
MarJay said:
Except V8's are road legal, whereas twin engined cars are not IIRC.
Please don't make stuff up on ph. You'll get caught out.
He is half right - V8 ARE road legal.

Mr Dave

Original Poster:

3,233 posts

194 months

Friday 2nd July 2010
quotequote all

Surely with both engines being matched for throttle position and rpm and the gearing being the same then both engines can only do the same work as one?

Would the car not be only able to go through each gear at a certain speed? I dont see where this extra power is useful if you see what I mean?

But then 4wd cars? But like for like they are slower than a 2wd car of the same power and weight due to losses.

Like if two cars exactly the same were attached together one behind the other, (say two 1000kg 100bhp cars, with each car being stripped out to 500kgs to make weight a non issue), I cant see that being massively faster in a way that doubling the horsepower would.

I think Ive thought about it too much and really gotten myself lost. I think Ive properly confused myself and need a lie down and a cry.



R1chardP

89 posts

165 months

Friday 2nd July 2010
quotequote all
I think that half of us are talking about one thing and half are talking about another.

It is not the same to have two engines in the same car controlling the front or rear wheels independently as it is having two engines feeding a common diff to power only the rears.

In fact, having two engines powering a common diff is exactly how a hybrid works (or KERS for that matter) because regardless of whether they are engines or motors you have more than one device doing work simultaneously on a common dff.

Quite how you mate the two up so that the system works at various speeds would be interesting - anyone know?

s3fella

10,524 posts

186 months

Friday 2nd July 2010
quotequote all
supersingle said:
MarJay said:
Except V8's are road legal, whereas twin engined cars are not IIRC.
Please don't make stuff up on ph. You'll get caught out.
Actually he is sort of right. Twin engine cars are legal in UK, but not in many Euro countries, inlcuding France IIRC.