28 replies to this topic

[mickymcg1]

One thing my friend and I were thinkin is what would be the best way to fuel it. I mean running 2 engines from 1 fuel tank. (and on that subject where to mount the tank, but that problem is along way off). Would u need 1 big fuel pump or 2 pumps?? If i were to run 2 pumps I could only switch 1 on and run say rwd only which would be easier on fuel if I had to do any long drives, to a track day for example :) or could this work with 1 pump and a valve of some discription.
Would 1 pump work at all considering it would need to pump fuel to 2 different engines that aren't the same distance ie it would have to travel further to the front engine than the rear.

Sorry if this is a load of questions but I'd rather look silly askin too much than find out 6 months and 10k into the build

Cheers
Micky

[Alan Carruthers]

Do it my man, would be fantastic, had genuinely been thinking about it myself but going down the fwd route for the mo.

Hey, while you're there why don't you do twin engine in the back, check out http://www.fullonfabrications.co.uk/ I reckon this would be a more cost effective route than zcars which always seems to cost twice as much as people planned. Imagine tripple R1!!

When I'd thought about it I'd realised that fuel tank would be just one of the numerous issues... I'd thought maybe in passenger footwell having seen the following where the hyabusa is located there!:

http://www.genmay.co...ad.php?t=830052

This has got to be one of the most awesome builds out there, shell and new aero probably not everyone's cuppa but engineering is sublime.

Al

[SukiDawg]

That is rather tasty....

[mini_mad69]

People often comment with this that you need both engines to produce exactly the same power at the same time etc.

Not true, in that tiger that tiff drove, that was mentioned earlier he changed gear in each engine separately to show they work independently of eachother.

Each engine is working against a force, air resistance, the weight of the car etc
Having an extra engine to push is only going to remove stress on that engine.

Sounds like an interesting project!

[SukiDawg]

If both engines are working through a common transmission you're dead on - they can be a little out of sync with one another and it won't matter....

However, if you have one engine driving the front wheels and one engine driving the rear wheels it's a different story. Goes back to the old thing that you only have so much traction available at the interface between road and tyre - if you are in a corner and you apply the throttle in a conventional car - the available lateral grip at the driving wheels is reduced the more you accelerate. Hence power oversteer / understeer in rear / front drive cars.

If you grasp that concept, and apply it to a vehicle where the split of drive force at the front and rear wheels is variable because the motive force is produced by two seperate powertrains, then you have a vehicle where the front to rear mechanical grip balance is not only variable, but importantly it is variable with throttle application. A lot of these types of cars have so much chassis flex that this effect is masked by the general poor handling charcteristics anyway, but the fact remains that you will NEVER get the engines to run exactly together so there will always be an element of unpredictability from apex to corner exit.

Maybe it doesn't matter to laptime too much, because you have so much available engine power that you just wait until you straightened the thing up and then plant it in a straight line, but that approach doesn't generally reward the experienced driver in terms of enjoyment.

While on the subject of power-on handling characteristics, did anyone notice the amount of acceleration squat in the Z cars twin engine vid posted above? At each corner exit the outside front wheel of the car is lifting clear off the ground and the driver is having to come off the throttle and back again to prevent the car flying off the circuit. Although not wanting to go against the grain - it seems to me that having rear-trailing arm suspension on a rear engine car is fundamentally detrimental to the handling because you will always suffer from this massive accel squat unless you run the rear end so stiff that you compromise lateral roll stiffness... It seems to me that double wishbone rear suspension is the way to go - as then you can build anti-squat geometry into it without having to adopt a very high lateral roll stiffness.

For grass-track cars the advantage of massive rear weight transfer would be that you get additional grip at the rear wheels on the grass - so rear trailing arm arrangements work well in that specific environement. If however you are building a car to operate on tarmac rather than on low friction surface, your traction limit is a lot higher, and so compromising lateral grip for traction doesn't give anything like the advantage to lap time...

Anyone got any thoughts on that??

Edited by SukiDawg, 05 April 2012 - 11:52 AM.

[R1minimagic]

I like the twin engine cars in terms of engineering concept but i think a single engine car will always be better and will win hands down on a track

Also, with a twin engine, the driver will have so many things to try and concentrate on that it removes the natural ability to just drive the car! Trying to listen to 2 seperate engines doing their own thing must be very strange!

I spoke to Chris Allanson about the Tiger car that Tiff destroyed during the filming, he was very angry that he had to personally foot the bill and had a few choice words to say about Tiff Needell!!

Edited by R1minimagic, 05 April 2012 - 12:06 PM.

[Ruckus]

I spoke to Chris Allanson about the Tiger car that Tiff destroyed during the filming, he was very angry that he had to personally foot the bill and had a few choice words to say about Tiff Needell!!

That's interesting, what did Tiff/5th Gear do wrong in Chris's eye's ?

[fs1eman]

HI how is the twine engined mini getting on ? i am just in the process in doing 2 r1 engines in my mini 1 front 1 rear .good luck

[cooper_mark]

also have a look here at mikes twin xe mini...might give u a few idea's.....but if it's just bike power only then ignore my post...lol
http://www.twinenginemini.co.uk/

Edited by cooper_mark, 20 July 2012 - 10:46 PM.

[fs1eman]

[fs1eman]

[fs1eman]

[fs1eman]

[fs1eman]

_{well she's up and running noe just making fire wall sounds the dogsssssssssssssss will post some picks soon}