My 915 has given up the ghost, limping home on the last run on Wednesday. It had 70,000KM on it before I got it and judging from the engine it was mated to, had a hard life.
Around 10 days at the track in front of 240 hp of track abuse at my hamfists did it in.
This is the instigation I was waiting for to do an engine swap, so the race engine is going into the weekend road toy (and Targa entrant) with a supercharged 375HP going into the track car. Its the race car we are discussing here.
I'd appreciate some suggestions for the following objectives and available parts;
The car is a race-only open class 1983 SC tub and suspension and transmission. It weighs in at 960kgs without me (80 kgs) with heavy seats and tail. The latter go for lighweight units soon so I wil be down to 920 kgs with a full cage. Doors may go to get to 900kgs eventually.
Suspension is torsion bar but I am considering coilovers and accompanying reinforcements with cage connections.
Engine is in progress now so the old one will be in temporarily. The new one will be around the following (I hope):
375hp at 6000rpm
300 ft-lbs from 3000 to 5500
Eastern creek is my home track, so I expect to do 50% of time here and there are only a few longer straights in the country (which is surprising given how bignfreakin flat it is.) Top speed on the main straight is around 260 kph. I think I want to leave 10% left on the top of top gear to allow for different tracks.
Tires will be 16" 9" fuchs in back with 2010mm circumference. These will get wider over time but assume that circumference.
I am interested in opinions, priceranges and availability of the following three choices:
1) Keep my 915 and modify/reinforce/spraylubricate with an lsd and sort gears.
2) 87-89 G50 which I understand will fit right in with the existing suspension. Cases seem to be at an extreme premium, with none to be had in Australia. I would need to purchase a donor and gearset from the US and ship here for assembly. Again, with LSD.
3. An investment in something like a heyward sequential shift. Although less exotic I also put the G50/50 in the same category as it would also require an entire new rear suspension (which I was considering anyway) so if I go that far I guess I might as weld in suspension points anywhere, which opens up all kinds of expensive options. And sequential is cool.Since I'm "all in" in Porsche anyway maybe the G50/50 investment is worth it anyway.
I dont think the 915 will handle the power anyway so #1 might be out but my experience with 915s is limited (to destroying them.)
So other points of debate could also be Hargett vs Wevo shifters and LSD choices. I am all but settled on an GT based on my experience with Paul. Options there are whether a welded spider, 40/80 40/65 or otherwise are likely to best fit the job.
My Excel seems to be corrupted so no good on running a gear chart but here's the program I've been playing with
http://www.carquip.com/parts/gchart/index.asp
Thanks all for your help.