Twin engined cars.

[dudleybloke]

SilverPhantom said:

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...

thanks for that.
i know about the twin engined pikes peak golf but not seen the roc before.

[Conian]

MGZRod said:

shirt said:

Streetrod said:

cockwomble & 'friend' in the blue oystermobile?

I was thinking more along the lines of:
'This week on My Name is Earl...'

Number 87, stole the Batmobile.

[Don1]

The aformentioned twin VR6.

[Mazda Baiter]

PhillipM said:

AS said before, you don't need to match the engines, all this crap about syncronising power and revs between them just came from a few bullst max power articles where the installers tried to make it look like they did more work than just bung a front subframe in the back.
The clutch and gearlinkage is the worst bit.

The engine is always, always, slowed down by the load - i.e. Accelerating the mass of the car - ergo, no matching is necessary as both axles on the car are connected by the road, and hence already synchronised.

Magic eh?

Anyhow, it seems a good idea down the pub until you realise that you've just added the weight of another crankcase, water pump, oil pump, crank, bearings, flywheel, clutch, transmission, shafts, hoses, radiator, etc, etc.
It's like that tandem bike someone mentioned earlier - great, you've now got twice the power for when you hit a hill!
But, you've also got two fat bds aboard to drag up there rather than one - the only thing it's helped with is it's made the bicycle feel a bit lighter..
Then you realise that a pair of 100bhp engines in a car are probably not going to be any faster than a nice little turbo bolted on your original 100bhp engine to give it 150-160bhp for about 20kg more weight....

Especially if it's the normal cut-and-shut and front subframe in the rear and hope-to-fk-it-doesn't-kill-you-in-the-wet approach to suspension geometery most of these heaps have...;)

This.

[anonymous-user]

A long long time ago in another galaxy, well, to be precise, it was 1996 and a race track just outside swindon, but you get the drift ;-), i had my rear mid engined volvo 480, and at the same event, dubsport showed up with the twinie golf, and i lost count of the times people came up to me and said "why have you only got 1 engine in your car"!! Thing is, when the track sesions started, my "crappy" single engined car was 12secs a lap quicker than the twinie...... 12secs, round castle combe!! thats a lot!!


(although, i did have a bulkhead between my engine and the passenger cabin, what on earth that golf was like to drive i have no idea, and the thought of a water hose (or worse and oil hose) poping off and drenching the driver/passenger in fluid at maybe 150degC didnt really fill me with confidence either.

As mentioned unless you are really funds limited, stick to just 1 engine properly installed!


(and if you really are funds / skills limited, how good do you think trying to get 2 engines to work properly is going to be??)

[DrTre]

mid rear 480? that is brilliantly bonkers in originality

pics? details? I'm intrigued!

[corozin]

Curiously IIRC the Dubsport MkIV twin VR6 above had a 2.8 Golf VR6 at one end and a 2.9 Corrado engine at the other. Both turbocharged, but one produced 280bhp and the other around 310bhp. The two engines shared a single cooling system though, so Ian Birch (the builder) mostly just drove it around on one engine, but could fired up #2 anytime it suited him and the second engine was already warmed up.

Didn't always go to plan though. At GTI International one year one of the cooling pipes at the rear engine let go during a ¼ mile run and sprayed hot coolant through the cockpit. Not nice.

[anonymous-user]

DrTre said:

mid rear 480? that is brilliantly bonkers in originality

pics? details? I'm intrigued!

unfortunately, as you are probably aware, digital cameras hadn't been invented in 1996 (and everyone was in black and white, spoke in posh accents and all had very well cliped moustaches, but i digress..) so i havnt got many pics of my Ovlov (backwards Volvo !!) it was a CCC modified car event finalist, and eventually i wrote it off in a faily massive accident on the Epynt Ranges!

Basically it was the 1721cc F series engine with a renault 16v head and a nice big garrett turbo, but misplaced backwards into car by about 6 feet to end up between the rear wheels.








Ah, happy memories!!

(Looking back at those pics (scanned from original prints) i had forgoten just how TINY that car is by current standards)

[DrTre]

Class
Did you do it just because you could sort of thing?
I agree too, how I lament the days of smaller cars.

[anonymous-user]

DrTre said:

Class
Did you do it just because you could sort of thing?
I agree too, how I lament the days of smaller cars.

Pretty random start really, got the car as accident damaged, took the engine out to fix my parents 440 (which they had decided to drive to devon without any engine oil, oops!) then was left with the rolling shell, and thought, thats a bit too good to scrap, so i fixed the accident damage (bent FOS chassis rail etc) and a mate said "that car looks like it should be mid engined rwd, so i made it mid engined rwd !! In the end, on the old "large" rally restrictor it had about 380bhp, weighed about a ton all up, and was a bit of a laugh.

[poo at Paul's]

poo at Paul's said:

jeebus said:

s3fella said:

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.

I thought it wasn't twin engines that are illegal but the fact that you couldn't have two engines running at the same time while on the road. (I dont know what the law is, just repeating what I heard ages ago so I could well be completley wrong).

Edited by jeebus on Friday 2nd July 23:30

Yes, that is the law which is I think what he meant, in France anyway. I think it is all ok in the UK? Having one rolling round the boot transporting it is not a problem! Having it connected and capable of being used is in many continental countries. Proving you weren't using it can be difficult as someone I know who took a twin engined car to a show in France found out!

[Conian]

Max_Torque said:

DrTre said:

mid rear 480? that is brilliantly bonkers in originality

pics? details? I'm intrigued!

unfortunately, as you are probably aware, digital cameras hadn't been invented in 1996 (and everyone was in black and white, spoke in posh accents and all had very well cliped moustaches, but i digress..) so i havnt got many pics of my Ovlov (backwards Volvo !!) it was a CCC modified car event finalist, and eventually i wrote it off in a faily massive accident on the Epynt Ranges!

Basically it was the 1721cc F series engine with a renault 16v head and a nice big garrett turbo, but misplaced backwards into car by about 6 feet to end up between the rear wheels.








Ah, happy memories!!

(Looking back at those pics (scanned from original prints) i had forgoten just how TINY that car is by current standards)

this is the 2nd volvo I have EVER liked and while the other one was good, this is very good!

[Mr Dave]

PhillipM said:

AS said before, you don't need to match the engines, all this crap about syncronising power and revs between them just came from a few bullst max power articles where the installers tried to make it look like they did more work than just bung a front subframe in the back.
The clutch and gearlinkage is the worst bit.

The engine is always, always, slowed down by the load - i.e. Accelerating the mass of the car - ergo, no matching is necessary as both axles on the car are connected by the road, and hence already synchronised.

Magic eh?

Anyhow, it seems a good idea down the pub until you realise that you've just added the weight of another crankcase, water pump, oil pump, crank, bearings, flywheel, clutch, transmission, shafts, hoses, radiator, etc, etc.
It's like that tandem bike someone mentioned earlier - great, you've now got twice the power for when you hit a hill!
But, you've also got two fat bds aboard to drag up there rather than one - the only thing it's helped with is it's made the bicycle feel a bit lighter..
Then you realise that a pair of 100bhp engines in a car are probably not going to be any faster than a nice little turbo bolted on your original 100bhp engine to give it 150-160bhp for about 20kg more weight....

Especially if it's the normal cut-and-shut and front subframe in the rear and hope-to-fk-it-doesn't-kill-you-in-the-wet approach to suspension geometery most of these heaps have...;)

Edited by PhillipM on Saturday 3rd July 00:33

Edited by PhillipM on Saturday 3rd July 00:34

But you could have two turbos bolted to your two engines and have 300-320 bhp for 40kg more weight....

Im still confused.

[CraigyMc]

Mr Dave said:

But you could have two turbos bolted to your two engines and have 300-320 bhp for 40kg more weight....
Im still confused.

You'd have 2x the power, and you'd need 2x the radiators, transmission,exhaist, etc, etc.

You'd have a heavier car because of all the extra kit required to get the second engine to work, so 2x the power wouldn't equate to 2x the speed.
The extra engine adds weight so you will end up with a power to weight ratio of somewhere well under 2x the original, one-engined car.

You asked about performance. If all you want to do is go in a straight line, then 2 engines isn't so bad. If you want to corner, though, you should be aware it will always be worse than a single engine.

As a matter of fact, with most cars, 2 engines means one in the front, and one in the back.

There's a thing called a polar moment of inertia: It's hard to describe but an example would be to imagine the car as a barbell (like in weightlifting).
The weights at each end of the barbell are like the two engines in one of these monster cars.
Try turning the barbells as if they were a car going round a corner - rotating in the same way as a helicopter rotor.
The inertia of having these two big weights at each end means that it's

1. hard to start turning
2. hard to stop turning, once you've managed to get it going

Now, imagine the exact same weight, but the bar is shorter - like a dumbbell. The weights being closer to the middle means that they are:

1. easier to start turning
2. easier to stop turning

That's polar moment of inertia, and it's why instead of having the weight at each end of the car, it's much better to have the weight near the middle of the car (as in all proper racing cars, and exotic road cars).

If you want to go round corners, you'd be better off with the original, single-engined car than the two-motor thing.

Round a track, 2x the power with more weight than the original car, and an inability to corner fast would mean the original car stands a fighting chance of being quicker.

To put it another way: what do you think, when you say "performance" ?

Craig.

[Mr Dave]

CraigyMc said:

Mr Dave said:

But you could have two turbos bolted to your two engines and have 300-320 bhp for 40kg more weight....
Im still confused.

You'd have 2x the power, and you'd need 2x the radiators, transmission,exhaist, etc, etc.

You'd have a heavier car because of all the extra kit required to get the second engine to work, so 2x the power wouldn't equate to 2x the speed.
The extra engine adds weight so you will end up with a power to weight ratio of somewhere well under 2x the original, one-engined car.

You asked about performance. If all you want to do is go in a straight line, then 2 engines isn't so bad. If you want to corner, though, you should be aware it will always be worse than a single engine.

As a matter of fact, with most cars, 2 engines means one in the front, and one in the back.

There's a thing called a polar moment of inertia: It's hard to describe but an example would be to imagine the car as a barbell (like in weightlifting).
The weights at each end of the barbell are like the two engines in one of these monster cars.
Try turning the barbells as if they were a car going round a corner - rotating in the same way as a helicopter rotor.
The inertia of having these two big weights at each end means that it's

1. hard to start turning
2. hard to stop turning, once you've managed to get it going

Now, imagine the exact same weight, but the bar is shorter - like a dumbbell. The weights being closer to the middle means that they are:

1. easier to start turning
2. easier to stop turning

That's polar moment of inertia, and it's why instead of having the weight at each end of the car, it's much better to have the weight near the middle of the car (as in all proper racing cars, and exotic road cars).

If you want to go round corners, you'd be better off with the original, single-engined car than the two-motor thing.

Round a track, 2x the power with more weight than the original car, and an inability to corner fast would mean the original car stands a fighting chance of being quicker.

To put it another way: what do you think, when you say "performance" ?

Craig.

So you are saying that the chavs that do this to their corsa/golf/other chav hatchback are chav and havent a good grasp on vehicle dynamics.

But it does give you double the horsepowers, although its best not asking about actual real world performance.


So a car with 2x 100bhp engines that all up weighs 1000kg isnt as fast as a car with 1x200bhp that also weighs 1000kg?

[CraigyMc]

Mr Dave said:

So a car with 2x 100bhp engines that all up weighs 1000kg isnt as fast as a car with 1x200bhp that also weighs 1000kg?

Precisely. "Fast" being a measure that includes cornering.

If we're only talking about a straight line, it depends if the car had a 4 wheel drive transmission to start with. If it did, the single engined car is going to be faster everywhere.

If the original car was two wheel drive, the chances are that the 2-engined car would be slightly quicker at acceleration, because it's going to have 4 driven wheels against 2 on the original car.

The 2-engined car would have a slower top speed because the transmission losses will be higher (given that it has two gearboxes).

All other things being equal, a single engined 200bhp car will be quicker than a two engined 200bhp car at top speed, and at cornering, and it won't be slower in any way.

C

[PhillipM]

The point is the 2 x 100bhp car isn't going to weight the same as the 1 x 200bhp car in the first place.

But yes, the handling would be worse.
Want more power? Tune the original engine.
A bit extra again? Turbo time
Want even more power? Fit a bigger engine.

Edited by PhillipM on Saturday 3rd July 18:53

[CraigyMc]

PhillipM said:

The point is the 2 x 100bhp car isn't going to weight the same as the 1 x 200bhp car in the first place.

But yes, the handling would be worse.
Want more power? Tune the original engine.
A bit extra again? Turbo time
Want even more power? Fit a bigger engine.

Edited by PhillipM on Saturday 3rd July 18:53

and if that fails, vtec.

and if that fails, throw a can of redbull.

[Mr Dave]

PhillipM said:

The point is the 2 x 100bhp car isn't going to weight the same as the 1 x 200bhp car in the first place.

But yes, the handling would be worse.
Want more power? Tune the original engine.
A bit extra again? Turbo time
Want even more power? Fit a bigger engine.

Edited by PhillipM on Saturday 3rd July 18:53

I could make it weigh the same.


And in extension to your post
Want more power? Tune the original engine.
A bit extra again? Turbo time
Want even more power? Fit a bigger engine.

Want even more power? Fit 2 bigger engines with turbos.

[PhillipM]

Mr Dave said:

Want even more power? Then you didn't fit a big enough engine or turbo

Fixed.