Penguinracer

Okay notwithstanding all the good natured 928 v 951 banter. If you got three guys together to put together a low budget racer for the Nurburgring VLN 24 hour races would you use a supercharged 928S4 manual or a tuned 951? Here in the UK a reasonable 250 bhp 951 costs about £6k - £8k ($US12k - $US16k) & a 928S4 costs about £8k - £10k ($US16k - $20k). Jon Mitchell can build a reliable 3.2 litre 8 valve turbo crate motor (500 bhp & 550 lb/ft) with a Garrett ball bearing turbo for about £11k ($US22k). If three guys were to pitch in £10k ($US20k) each to buy & prepare a car for a 'Ring 24 hour race - which would be your mount of choice?
The 'charged 928 will be less stressed but you've the weight to deal with. The 951 has got the weight advantage but a 24 hour race would put some big stresses on the 'plant. Those of you who have been to the 'Ring will know that's it's very fast (a lot of 3rd/4th & 5th), this will benefit cooling compared to a track which alternates hairpins with straights & has a lot of 2nd & 3rd gear corners.
Total budget = £30k ($US60k). A cheap independent garage in UK charges about £40/hr ($US80/hr). What are your thoughts on the fantasy budget endurace car?

evil 944t

I would not go big bore 3.2lt for an endurance race. I would stick with a well built 2.5ltr and just run around 350-400hp. That is plenty and would not stress the car out. It would also save some cash and then you can buy spare parts/tires/brake etc..

Penguinracer

Thanks Dave.
I'll drop a line to your business e-mail regarding my details should Charlie get s batch of arms made.
I'm interested in your dry-sump system but it may be a bit expensive for me. i fi ti is do you a recommended wet sump baffle or pan?
cheers,
Tim

Vilhuer

While here for biannual 928 bashing thread might as well answer to this thread too. SC is not best option for 24 hour race. I would build 6.5L NA stroker engine. £11k ($US22k) is more than enough for dry sump 500+ hp engine. NA engine is always on average more reliable than turbo or SC and if hp limit is set so low why not make it as reliable as possible. 928 racer weight can be taken down to 2700-2800 lbs without too much problems. Depending on rules of course.

anders44

I've seen 951's on the VLN, but never 928's. you really really need to test it before you try lasting 24 hours.

have you also read your class rules?

we have been contemplating putting a team togheter ourself, but so far it's only thoughts. I however know both audi/bmw drivers and it seems like a blast.

everything on my 951 is rigged with this track alone in mind

evil 944t

Don't think of it as a bashing rather than a fun get together, lol..

I agree a N/A is reliable(although I would concentrate on reliablity rather than a stroker), a well built unstressed turbo motor is fine too. They have been used for years on many makes/models of race cars.

What ever motor you decide, keep it simple, use a good oil cooler/cooling and take care of the motor. Stay away from extreme RPMS.

For the oil system, I have a great wet sump setup that is a little nicer than the standard door hinge mod but obviously, if money was not an option, dry sumping is the way to go.

Vilhuer

In 928 building stroker server also other purposes than just displacement and hp increase. Its part of package to fight against 2/6 rod bearing problems as most cranks use Chevy SB rod bearings.

reno808

I would not built a 3.2 litter for a 24 hr event i would go with dave on the 2.5 or 2.7 max and make around 400whp very well tuned with good suspension and tires. What kind of cars are in your class? what do there weight and hp look like?

333pg333

Yes, what are the rules governing mods?

AL951

I would go with a 3L 16v engine. I would have to be dry sump. running high CR(9:1) , low boost no more that 18 psi. I estimated a well develop engie like that should produce arould 600Bhp and it should have no problem lasting the distance. Specially if you could keep the revs low.

Of course, a well sorted chassis will make the engine work less hard and turn in better lap times.

Regards,
AL

sweanders

IIRC they 928's and 944's are to old. There is an age limit for the 24H race.

Diver944

Interesting comparison Penguin. Of course I am biased but I know when my 3.2 was specced that Jon categorically stated that blockwise it was far, far stronger than a standard 2.5 or 3L purely because of the way the sleeves and the HG solution braced the entire block. Therefore I would say to go for a 3.2 but run it with very conservative boost for longevity and a non BB turbocharger as you don't need super fast spooling.

A 3.2 will make over well 400bhp and nearly 500lbft at only 15psi boost and you will have all the low down grunt you ever need just from the engine, so spec the turbocharger for a higher peak power than mine and then you'll have just what you need for a racecar IMHO

333pg333

Also we are all saying to keep the revs down for obvious reasons, but then saying to go a 4v head. Why not keep the 2v head with a 6500rpm limiter and utilise the tq and the high ratios of the stock gearbox. Sort of a fast Autobahn cruise missile, just like the designers intended.

Penguinracer

I haven't looked at the rules but there are some 24 hour races where the field is quite open. There's a mid-'80's (W126?)Merc 500 SEC which contests some of these 24 hour races - apparently it's a team requirement that at driver changes the driver puts another CD in the CD player! I'd heard that this old Mercedes Coupe (stock apart from brakes & suspension) had been contesting these races (may be a couple a year) for about 4 years without having been taken apart. It was this tale which inspired me as to the possibilities for an ultra-low budget (relatively speaking) 951 or 928 Endurance Racer for a couple of mates to prepare to contest these races for the sheer hell of it!
If anyone knows more about that 500 SEC & its team I'd be keen to know more!

Diver944

Checkout the Britcar forum on Pistonheads after last years 24Hrs at Silverstone. I am pretty positive that this team with the old Mercedes 500 SEC came over, finished the race and then drove it back to Germany fully laden with all four drivers and the spare parts in the car. There was quite a bit of discussion about it amongst the other drivers at the time.

A group of us nearly convinced Jon M to build us an endurance 944 for this years 24HRs using a spare shell he had lying around. Unfortunatley we dreamt the idea up too late to do anything about it. I have a real desire to complete a 24HR race as I know I am not the fastest or bravest driver out there but I can be pretty consistent and gentle on the car which is what you realy need to make the car last the distance.