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Bias for 4wd
zzrpowerd-locost - 5/12/05 at 01:32 PM

On a 4w system what is best?

Equal front/rear drive

More front than rear

More rear than front

Just pening ideas for twin engine 4wd design

froggy - 5/12/05 at 01:42 PM

thought about this myself the stumbling block is getting both motors to drive one transmission before drive is split front to rear otherwise mechanically front and rear drive have no link and would swap ends without warning

NS Dev - 5/12/05 at 01:46 PM

I think (personally) that the ford/ff developments system, with 66/33 torque split (66% rear) is about spot on. Any more to the front and understeer starts to set in with a vengeance.

Any track dayers on here will confirm that as they merrily drive round the outside of terminally understeering tyre slaughtering subaru imprezas!!

MikeR - 5/12/05 at 01:50 PM

of course - if you're not used to rear wheel drive, want to pootle aroudn the roads ..... more front wheel drive is what you're used to and has less chance of swapping the ends on a wet roundabout.

(sorry, NS Dev just wanted to put the other side forward from someone who drives a fwd car )

Depends what you want the car to do, what youre used to and where you'll be using it.

Howlor - 5/12/05 at 01:50 PM

Why not go for full 'bling' and have an active centre diff so you can control the split?!

froggy - 5/12/05 at 02:00 PM

yep im with nsdev on this one ,im hoping that the 60/30 split still let my car behave pretty much as a two wheel drive but give me more control in the wet. after driving a customers westie in the rain which is an experience i dont want to repeat! im still not sure if by leaving the lsd in the front diff on mine will cause it to understeer, no-one has offered an opinion yet

Howlor - 5/12/05 at 02:02 PM

Froggy, what type of LSD do you have in the front diff?

froggy - 5/12/05 at 02:08 PM

viscous its a 7" sierra same as my rear diff but with 3.15 gearsets, i think that il have to try it and see, its been done before but dax used a 6.5 open front diff on their quadra but my engine is a loooong way back ,my rear prop is 11" long and the gearstick is where the box meets the bellhousing

Howlor - 5/12/05 at 02:10 PM

If you end up with too much under steer is it possible with a viscous unit just to use a different lube grade to give less/no LSD function?

froggy - 5/12/05 at 02:14 PM

cheers for that ,all a bit academic really as like a true petrolhaed ive started another project before finishing the last one

NS Dev - 5/12/05 at 02:45 PM

quote:
Originally posted by Howlor
If you end up with too much under steer is it possible with a viscous unit just to use a different lube grade to give less/no LSD function?


No, because the lube that you can get at is not the lsd fluid, that is contained within the lsd itself, not the outer casing.

The "fluid" is pretty trick stuff, totally unlike any oil you have come across! It is a fluid which solidifies under compression but liquifies in tension. Make up a paste mix of cornflour and water and you'll get something similar, though I wouldn't try and use it in a diff!!

You won't want an LSD on the front in any car used on tarmac. Useful on loose going but on tarmac you'll never need it.

Howlor - 5/12/05 at 02:50 PM

I'll try the cornflour and water later and report my findings. Very interesting you learn something new everyday especially on here!

andyd - 5/12/05 at 03:06 PM

quote:
Originally posted by NS Dev
Any track dayers on here will confirm that as they merrily drive round the outside of terminally understeering tyre slaughtering subaru imprezas!!

Surely that's the last place you'd want to be... around the outside! They'll run into you!

JAG - 5/12/05 at 03:15 PM

quote:

I'll try the cornflour and water later and report my findings


Proper Custard contains cornflour and behaves exactly the same.

I was watching a TV program called "Brainiacs" (one of the digital channels on freeview - can't remember which) were they do lots of silly experiments.

They filled an outdoor swimming pool with custard and then the presenter walked across it and didn't sink

As soon as he stood still for a couple of seconds he began to sink. It took three people to pull him out because of the way the fluid behaves - a bit like sinking sand. If you stay still you sink - if you struggle it holds and won't let go

These fluids are called non-Newtonian i.e they don't behave in the manner described by Newton.

andkilde - 5/12/05 at 03:22 PM

quote:
Originally posted by NS Dev
quote:
Originally posted by Howlor
If you end up with too much under steer is it possible with a viscous unit just to use a different lube grade to give less/no LSD function?


No, because the lube that you can get at is not the lsd fluid, that is contained within the lsd itself, not the outer casing.

The "fluid" is pretty trick stuff...


The fluid inside the LSD units is available -- industrially it is used in hydrostatic drives and Caterpillar sell a number of different grades. The rally boys over here install fill plugs in the diffs and play with the different rheopectic oils.

Cheers, Ted

andrew morrall - 6/12/05 at 04:32 AM

CCC had an article on a twin engine BEC a couple of years ago. Can't remember the details of the setup.

froggy - 6/12/05 at 11:15 AM

i think they are a brilliant marketing exercise but they are all about straight line speed i followed a twin engined golf on a track day and it looked about as stable as my reliant van on thity year old cross ply,s

zzrpowerd-locost - 6/12/05 at 12:08 PM

quote:
Originally posted by froggy
i think they are a brilliant marketing exercise but they are all about straight line speed i followed a twin engined golf on a track day and it looked about as stable as my reliant van on thity year old cross ply,s


Thats cos they are 50/50 splipt on power!

BTW if anyone has seen a burgandy mk2 golf with 20v with turbo AND superchanger, spaceframed front end or a Black mk2 golf with rear mounted supercharged VR6 on the show scene, I did and the Oil cooler and brake circuits on them Oh and supplied the silicon hose

Used to work for a hydraulic company, got all the motorsport jobs

[Edited on 6-12-05 by zzrpowerd-locost]

zzrpowerd-locost - 6/12/05 at 12:15 PM

20v super turbo Rescued attachment swaprk1.jpg
Rescued attachment swaprk1.jpg

zzrpowerd-locost - 6/12/05 at 12:16 PM

Supercharged VR6 mid mount Rescued attachment swapvr1.jpg
Rescued attachment swapvr1.jpg

MikeRJ - 6/12/05 at 01:57 PM

Surely the ideal split will depend a great deal on weight distribution and the kind of surface you are driving on?

NS Dev - 6/12/05 at 02:02 PM

exactly, which is why in the "ideal" world you want an adjustable torque split.

I know I can't afford that though, well, not in a package that will work in a locost anyway. The nearest compromise is the one that Harry Ferguson/FFD came up with years ago and Ford have used since, the 70/30 or thereabouts split.

It's a compromise that works in most conditions. A touch understeery in really dry grippy conditions and a tad oversteery in really slippy going but basically sound.........i.e. it works!

NS Dev - 6/12/05 at 02:04 PM

quote:
Originally posted by andyd
quote:
Originally posted by NS Dev
Any track dayers on here will confirm that as they merrily drive round the outside of terminally understeering tyre slaughtering subaru imprezas!!

Surely that's the last place you'd want to be... around the outside! They'll run into you!


Heh Heh!!! True, True, ok nip round the inside then, shouldn't be too tricky, you'd have plenty of time to make your mind up with most of em!

froggy - 6/12/05 at 03:01 PM

there is an article in next months ppc about twin engined kits .to get back to original thread i thought that the idea was to use two bike engines one driving the front one driving the rear, iirc volkswagen did something with a sirroco very early eighties. dont think it was a success though. twin engined 4wd with torque split front to rear (deep pockets reqiured)

NS Dev - 6/12/05 at 03:13 PM

2 seperate engines driving opposing ends of a car is a nightmare. I would NEVER consider it.

It is an engineering BODGE of the very highest order. Great at the pub, and in a straight line, totally and utterly useless for anything else.

What I think would be interesting is a mid engined car with 2 bike engines either "piggyback" or side by side driving the rear wheels, just as they use in class 10 autograss cars.

There are a lot of twin engined minis/mini pickups around in autograss and on the road. This setup but with some nice bodywork and 2 seats would be good fun, and with weight over the driving wheels would actually grip and go quite nicely.

The transverse rear-mid engine setup is very quick in a straight line, but can be made to turn in nicely too. If you look at a lot of grasstrack cars now (I know the setups are VERY different to tarmac but the principle of maintaining good wheel to "road" contact all the time is exactly the same) they have the transverse engines mounted BEHIND the rear axle line!!

That is NOT the setup for tarmac....or driving with the steering wheels pointing the "right" way for that matter, but 50-50 ish weight distribution is not tricky with the rear-mid engined setup.

zzrpowerd-locost - 6/12/05 at 04:31 PM

quote:
Originally posted by NS Dev
2 seperate engines driving opposing ends of a car is a nightmare. I would NEVER consider it.

It is an engineering BODGE of the very highest order. Great at the pub, and in a straight line, totally and utterly useless for anything else.


Hhmmmm.....is that why z cars have done it with a ultima??

Two 'busa turbo's, one driving front, one driving rear.

zzrpowerd-locost - 6/12/05 at 04:35 PM

quote:
Originally posted by froggy
there is an article in next months ppc about twin engined kits .to get back to original thread i thought that the idea was to use two bike engines one driving the front one driving the rear, iirc volkswagen did something with a sirroco very early eighties. dont think it was a success though. twin engined 4wd with torque split front to rear (deep pockets reqiured)


PPC????

froggy - 6/12/05 at 05:13 PM

practical performance car

zzrpowerd-locost - 6/12/05 at 05:26 PM

quote:
Originally posted by froggy
practical performance car


ooohhhhh!!!

britishtrident - 6/12/05 at 06:20 PM

Twin engined cars have a history of almost a century of dismal failure. , Every 30 years or so someone thinks they have invented it for the first time. So much is wrong with the whole concept that anyone who builds such a vehicle deserves all the trouble it gives them.

Cyclic theory of history --- don't repeat the mistakes of the past.

NS Dev - 6/12/05 at 06:42 PM

quote:
Originally posted by zzrpowerd-locost
quote:
Originally posted by NS Dev
2 seperate engines driving opposing ends of a car is a nightmare. I would NEVER consider it.

It is an engineering BODGE of the very highest order. Great at the pub, and in a straight line, totally and utterly useless for anything else.


Hhmmmm.....is that why z cars have done it with a ultima??

Two 'busa turbo's, one driving front, one driving rear.



Correct!!!

I normally have a lot of time for Mr Allanson, but I think that project was a BIG mistake! (and I don't know, but I wonder whether he is thinking the same!!) You may know more about it than me, but it was certainly done outside of the Ultima "factory" approval! (my mate runs Ultima)

Time will tell whether they can take the record off the factory car, but it is interesting to see that apparently it was "complete" at this years autosport show in January, but has still not set any records?????????????????

If it does set straight line records, then so what, get it on a track and set a quicker lap than a "factory" car with its nice simple single 640hp v8. Drag cars are fast in a straight line, if you want to do that then build one!

froggy - 6/12/05 at 07:00 PM

the words FRAGILE and HAND GRENADE spring to mind, whoever is paying for this car must have a sense of humour.cars like these never deliver what they promise and cost so much noone will ever admit it either, bit like a 500 bhp cossie sierra great on paper not much fun to drive

NS Dev - 6/12/05 at 07:11 PM

Quite right

EXACTLY as you say, 500hp cossies are great to talk about at the pub, but in reality are hopelessly frustrating to drive. (well, I have not driven one with 500hp, but 400 was bad enough!!!)

The big virtues of the Ultima, are despite it's appearance etc, it is actually pretty simple, so less to go wrong, and it is brutally fast, yet reasonably (ok, not VERY!) practical.

We certainly had no real practicality issues taking the factory demo car to Le Mans this year, including tent and sleeping bags and luggage etc. The car was very driveable, not as good in that manner as the previous lower powered demo cars, but then this does have vast amounts of power and is still only carburettored!

I'll believe the turbo busa one when I see it cover 8-10,000 miles over 3 years or so and how many times it breaks etc.

On the way to Le Mans we stopped in a layby for some "frites" and another Ultima pulled up. I can't recall the owner's name, but it was Ford V8 powered, only a mild engine, but it had covered 75,000 miles since he built it, and is used as his only car!!!!!!!!!!!!!!!!!!! It did look "tired" but not many kit cars are used as daily drivers and cover 75,000 miles in the space of a few years and do it reasonably reliably!!

jono_misfit - 6/12/05 at 07:32 PM

If you stick a engine in the front do you not end up with the problems you get with a normal FWD. Ie a heavy engine up front turning the front wheels?

Even if its a bike engine it must still weigh 70 - 80Kg with box. Lighter than a cars but still a big mass to consider. Are you thinking about putting it infront or behing the axle line?

Dub sport did a twin engined golf about 5 years back if i remeber correctly. Was in CCC. Seem to remember Dave Walker saying it was bruttaly fast down the straight but wasnt tooo bad in the corners all things considered.

jono

[Edited on 6/12/05 by jono_misfit]

froggy - 6/12/05 at 10:35 PM

thats the one i saw at one of ccc,s track days ,wouldnt say it was that quick it kept up with my lotus carlton well enough but i seem to remember he f$$cked his brakes after a few laps. it made about 350Bhp and wieghed around 1200kg

zzrpowerd-locost - 7/12/05 at 01:23 PM

quote:
Originally posted by jono_misfit
If you stick a engine in the front do you not end up with the problems you get with a normal FWD. Ie a heavy engine up front turning the front wheels?

Even if its a bike engine it must still weigh 70 - 80Kg with box. Lighter than a cars but still a big mass to consider. Are you thinking about putting it infront or behing the axle line?

Dub sport did a twin engined golf about 5 years back if i remeber correctly. Was in CCC. Seem to remember Dave Walker saying it was bruttaly fast down the straight but wasnt tooo bad in the corners all things considered.

jono

[Edited on 6/12/05 by jono_misfit]


The ultima has both engines in the back afaik

Apparently in also has a clever computer controlling the power output and delivery of the engines

I was thinking of a 7, both engines where they should be but one facing the rear wheels and one facing the front!

Im starting to think its going to be alot of hassle!

NS Dev - 7/12/05 at 01:38 PM

thats what allanson (z-cars) did with the 4wd tiger twin bike car that they built.

that didn't go round corners either ( glib comment but it sums it up )

NS Dev - 7/12/05 at 01:39 PM

The clever computer in the Ultima is a Motec EMS and traction control system, which costs about the same as the whole engine in the factory demo car!

zzrpowerd-locost - 7/12/05 at 01:57 PM

quote:
Originally posted by NS Dev
The clever computer in the Ultima is a Motec EMS and traction control system, which costs about the same as the whole engine in the factory demo car!


zzrpowerd-locost - 7/12/05 at 01:58 PM

quote:
Originally posted by NS Dev
thats what allanson (z-cars) did with the 4wd tiger twin bike car that they built.

that didn't go round corners either ( glib comment but it sums it up )


twin engines driving rear wheels it is then!

froggy - 7/12/05 at 02:43 PM

or perhaps a v8 and a nice holiday with the money you will have saved

zzrpowerd-locost - 7/12/05 at 04:17 PM

quote:
Originally posted by froggy
or perhaps a v8 and a nice holiday with the money you will have saved


NNoooooo.....twin bike.......two 600's

zzrpowerd-locost - 7/12/05 at 04:21 PM

You may ask why?

Cheap to source, more power than one bike engine, insane exhaust note.....

I will think of more reasons

NS Dev - 7/12/05 at 04:33 PM

quote:
Originally posted by zzrpowerd-locost
quote:
Originally posted by NS Dev
thats what allanson (z-cars) did with the 4wd tiger twin bike car that they built.

that didn't go round corners either ( glib comment but it sums it up )


twin engines driving rear wheels it is then!



Have to say that CAN be an interesting format, but it needs to be mid engined (twin mid engined!) to get the weight over the driving wheels.

Allanson also built a twin engine RWD westfield before the 4wd twin engine tiger. The westy lacked traction in a very severe way!!

Twin transverse mid engined bike engine layout is promising though and easy to do with chain drives onto a common shaft with cv's each end......basically a twin side by side engined Westfield XTR or Radical........now that would be much more interesting.......it has been done before but there aren't many around!