What gearbox / rear diff - BIG power?

[WabTheKing]

put nankang tyres on, they have so little grip you gearbox will have no strain whatsoever

[quattronutter]

it will still work out cheaper running standard boxes and replacing them when they die,there are lots of other deciding factors which will affect the longevity of the box

[4WheelDrifter]

Will do a good bit of research on the boxes to see at what torque they are failing. If anyone can let me know if they have had a failure (on a quattro) and what torque they were putting through it, that would be great.

I broke an 01A ARV 5 speed with ~400Nm. The input shaft bearing was typically noisy, but the front diff went in the end when the internals escaped from the casing. However, it did survive 3 years of my abuse, so that wasn't too bad IMHO.

put nankang tyres on, they have so little grip you gearbox will have no strain whatsoever

Good tip Wab.

[Error404]

I realise that - But there's not a cat in hells chance I'm having an auto box on a track car!

There's always a cheaper way to do something. The whole car is going to cost me around £30k to build, which for the power we are talking about IS peanuts (rather than chicken feed). That's the currency I work in, I'm afraid!

I seem to remember Gemballa or Ruff have built a 1000bhp motor. Maybe a porsche box is the way forward? For some reason, I thought the Audi gear was tougher, or at least had the potential for toughness - The VW boys are just about to put around 700bhp through standard 4 motion box and haldex gear.

Hate to piss on your parade mate, and no disrespect, but you are dreaming if you think you can obtain that kind of power for that kind of money
As well as the cost of parts, the huge cost of development, breakages and wear and tear parts will be well over £100k, then an ongoing enourmous cost of maintainance. As i've said, when you start running upwards of 800bhp, engines and gearboxes are regular wear and tear items... and not cheap ones at that. You will be pushing boundaries noone else has, and that costs money - lots of it. A lot of the guys on here running big power have probably spent upwards of £20k and only running about half what you want to acheive.
Norris Designs have the quickest Evo in the world circa 900 bhp, and it is a track machine..... they have spend over £250k in development AFAIK.

You are better off aiming for 600bhp reliably, and going super lightweight instead of huge power.... weight is the enemy of the track car.
A 600bph car that weighs 750Kg will be significantly faster round a track than a 1200bhp car that weighs 1500kg..

[quattronutter]

Hate to piss on your parade mate, and no disrespect, but you are dreaming if you think you can obtain that kind of power for that kind of money.
As well as the cost of parts, the huge cost of development, breakages and wear and tear parts will be well over £100k, then an ongoing enourmous cost of maintainance. As i've said, when you start running upwards of 800bhp, engines and gearboxes are regular wear and tear items... and not cheap ones at that. You will be pushing boundaries noone else has, and that costs money - lots of it. A lot of the guys on here running big power have probably spent upwards of £20k and only running about half what you want to acheive.
Norris Designs have the quickest Evo in the world circa 900 bhp, and it is a track machine..... they have spend over £250k in development AFAIK.

You are better off aiming for 600bhp reliably, and going super lightweight instead of huge power.... weight is the enemy of the track car.
A 600bph car that weighs 750Kg will be significantly faster round a track than a 1200bhp car that weighs 1500kg..

so true....better off losing weight than adding more if its for track use

[quattronutter]

your best bet would be to pick up something like a crash damaged b5 rs4 or rs6 and use engine and running gear,if your keeping weight to approx 1000kg you should have well over 500bhp per tonne on standard running gear

[Error404]

i'd concentrate on reliable power of 600ish bhp, losing weight and developing a decent aero package. A well planned out undertray and brushes to create a psudo venturi will work well.

[4WheelDrifter]

I think I'd concentrate on a good reliable 400 something bhp, then learn how to drive properly. 'Cause last time I checked I wasn't Walter Röhrl.

[20vK]

Thanks for all the comments - it makes for interesting reading!

I am concentrating on weight, too. I'm rebuilding the whole outer bodyshell in carbon fibre. I'm doing it all myself, so I save money. The car is also going to be spaceframed at the front and back, with a full multipoint rollcage. I'm doing this myself, too.

Flat engine tray and rear venturi are already incorporporated, plus some other aero tricks, if needed. Infact, I've looked at every single componant in the car, from the water pump, through to the sequential shifter I have sitting in my bedroom!

I designed a stand-alone haldex controller way before any other alternatives were out there. True, I didn't get it out to market - but I had no real intention of selling it. The tech guy at haldex (US) who I was talking to told me he had been asked to stop communicating with me after his boss read my email to him (on how I was planning to do it), so I guess I was pretty near the mark. I had it computing torque splits 7.5 times faster than the Haldex unit found on the first TT's. Now I understand that Haldex must have spent a few £mill on developing their controller, but surely you can see that someone with the right ideas can do it for less. It cost me less than £100 in electronics, and most of that was a prototyping board and a book on how to program microchips!

I understand that some parts are going to cost the earth, and if I ran the car at a constant 1000bhp, yes I agree that parts would explode / wear at an alarming rate! I have done the sums on what it takes to build the car and an engine capable of the power CAN be built within my budget. How long it lasts, is another matter - but like you say, noone has done it before, so I guess we just don't really know! That's not going to stop me trying to find out! I just want to build a car that's capable of hitting that kind of power, and last just a few laps of the nurburgring (3 if I'm lucky)!

As for development - yes you're right it has cost a lot. It's taken me 4 years to design and hours and hours infront of the computer doing research. I wonder how much that would have cost if I worked for a company like Norris - £200k? and that's just brainwork, no overheads to cover. Funnily enough, I've spoken to Simon about his injectors and ECU on his car, with regards to my project, so I guess I just saved a few more quid in development costs!

I understand where you are coming from, and that this is a massive undertaking, but it's something I'm going to try, whether it works, or not. If it keeps on exploding, well then I'll have to find a solution, or turn down the power! But I'm going to wait and see if I can explode some stuff first and at least say I had a go!

Thanks for the data and ideas that were mentioned, much appreciated

Rich

[shortsport]

A bloke i used to work with was presented with a Ruff Porsche to work on with gear box problems,couldn't realy get his head around it being that it was fully programmeable with a laptop so it's not going to be cheap

[shortsport]

If you look through that link I gave you and find the piece about gt40 and v8's they sugest that the Porsche G50 box is very strong.I can't wait to see this beast when it's finished.

[20vK]

Thanks for that link - haven't had a chance to properly read over it, but will do so at the weekend. I've saved it for reference.

Just been offered a custom dog box for around the £6k mark. Used once. Why pay £40k when you can get it for £6k?

That would push my spend up to £35k, which still isn't so bad. Fairly indestructable, too!

[Error404]

clutch will be a major issue too i'd imagine - what are you planning for that?

Hollinger and OS Giken sequentials are about £6-7k new - should be capable of containing up to 900-1000hp, but again, these require regular and expensive mantainance..... as with all race designed stuff, it does that job but is not built for long term use... you might be wise talking to some of the Skyline drag boys - Keith Cowie is/was knocking on the door of 1200bhp last time I heard - they might be able to help you with ideas / experience. I know they had custom made gear set to work in their OS-G box.

I still seriously doubt you will get anywhere near the power you are hoping for unless you win the lottery / strike oil

[20vK]

Even with all the money in the world, you won't necessarily get a big hp motor (unless you're buying a veyron, of course)! But if you have enough air (not too hot, please), and enough fuel and the head can flow it, and the motor can handle the power, you've got a good chance of hitting some big numbers. Controling the combustion temperature is right at the top of my list, since this is what leads to detonation so I have spent a lot of time designing the setup to reduce these as much as possible. There will be a limit, and I guess that is what will restict things on the engine side.

The rods (pauter) and other componants will be made to my top power estimation, so should be able to take the potential power made. Saying that, my biggest headache on this project has always been the transmission aspect, so i do understand your points on wear and rebuilding.

Twin plate clutch with HD assy, I expect. (around £1200) It's relatively streetable and I'm told it's holding 1000bhp quite nicely. If not, then a triple plate should certainly do the trick, with a spacer on the box and extended input shaft.

Just about to buy my air source, when I've saved the pennies, which is good for up to 1200bhp - I'll start low and gradually build up the boost. Other than that, I need fuel supply (around £1k from the states) and uprated internals on the engine. Head work will be done by a good buddy of mine and custom cams will be ground by another contact.

I think I'm going to stick with the quattro gear, until it fails and then probably rebuild it with straight-cut cogs. See what happens. If reliability becomes a big issue, (which I can totally agree with, Error404), then I can reduce the power and still have a very rapid motor. I can then make an informed decision on whether to invest in a different box, or keep it as it is.

Thanks for the box contacts - always handy for the research folder, and much appreciated!

Oh, there goes my oil well again, excuse me.....!

[Error404]

haha

you'll need to be running with top quality race fuel too - even the biggest and most efficient intercooler in the world won't cope with volume and speed with which your motor will be gobbling down (hot) air...
have you considered running on E85 or even methanol intead of petrol? cooler burn and far greater energy - that way you could reduce boost and help contain temps.