Porsche Enthusiasts Club Forum

Just to reiterate what Steve said, the main thing holding back engine rebuilds is the supply of main crank bearings and soon the rod big end bearings.

If this problem is solved then everything else is pretty easy to sort out.

end of play today, and car is ready to go on the jig!





the shell is so clean is such a great base to start with. not a spot of underseal on the whole car, thinking of fully stitch welding the shell, and extending the cage onto the front turrets. will also be modifying the front end to accept 951 rad and intercooler in its std position.

looking good. I like the idea of welding the shell and extending the cage.

Bloody hell, no messing about there!

Heres some inspiration

Mittelmotors CGT to GTS spec race car now running 340bhp on CIS and electronic dizzy, oh and 9'' Fuchs all round


Artz GTR


Monster no exspense spared GTR build http://www.924board.org/viewtopic.php?t ... sc&start=0


If the numbers rock up soon, I'd be doing an ultimate GTR build like the Artz/Richard Lloyds original Canon Le Mans version http://www.flickr.com/photos/antsphoto/8317897957/

wes thanks for all the info, very useful thank you!

steve the white gtr is my dream build! but I cant find those wheel arches anywhere! I could get some made up, but they wouldn't be cheap.

the next best thing is cgt kit, 9inch wheels look good all round!

will concentrate on the refresh of the shell and components for the minute. there is plenty to get stuck into before deciding engine tuning route and bodykit etc.

I need to learn more about cis tuning, and the costs involved, the reason I thought about going standalone and binning the cis is because I am much more familiar with tuning engines with this format, and mapping becomes less of a specialist thing.

for a race car can I remove any of the parts under the inlet manifold to make it all more simple? or are all the components required?

very happy with the progress, the car came apart very quickly and easily with no dramas!

keep the info coming!
nick

brake upgrade options? would like to fit some monoblock calipers. I think someone mentioned boxster brakes? which discs and is there a bolt on adaptor for calipers?

will likely be fitting 16inch fuch wheels

cheers

Or you could use 1985.5 951 hubs, trailing arms, brembos etc. Would be bolt on with just the need to drill the hub for stock speedo or switch out to digital dash

The guy in Sweden clearly got them from somewhere. I can't find his .SE forum link at the minute. Cedric on 924boarg.org knows him. There was a German company selling them for circa €5000 if I remember correctly but the site link is dead for the past 12 months.

front brakes?
I take it if I wanted to change to rear trailing arms from 951 they would need to be non abs items. I have some trailing arms from my 86 951 but they have abs hubs.

im not bothered about speedo as it will be a race/track car, but the car does have a digital dash fitted which reads from the front hub so don't need to worry about that.

5000 euros is mad! I could buy all the bits to make them from scratch and in carbon fibre for less than that! the hard bit is getting the shape right!

im thinking I want to get the car as light as possible, and this will give a decent performance gain. the shell is already very light, but I reckon I can get a fair amount off it. fg bonnet, doors, plastic hatch and windows, I think that lot could shed another 60-70kg with ease. not only will this make the most of any power achieved, but will see braking performance much improved aswell as less mass to get around the corners.

I wonder what final weight could be achieved! what is this car as std?

Period race GTS/R's were circa 950kgs. The magazines of the day said the stock turbo weighed in at 1180kgs, however I reckon if this weight isn't dry then its certainly without powered windows, mirrors, sunroof etc. My car now weighs in at 1100kgs with half tank of fuel and no driver.

Turbo race cars have gone down to 930kg IIRC. I've heard of 924NA getting below 900kg with extreme measures but you have to be careful of losing too much weight at the rear as traction then becomes a bigger problem.

951 brakes are tried and tested but I went for the Boxster 2.5/2.7 4 pot mono block calipers on the front. Discs are ATE grooved with standard Boxster pads. For the rear I fitted refurbished standard calipers with EBC 'Greenstuff' pads.

The mono blocks are ultra rigid and light and my set-up is awesome for a road car but would probably need different pads for track use.
The alloy adapters are pretty easy to make. I bought some years ago - I think it was from the 'dreaded' Porscheshop???
I should have just made them myself as when I came to fitting them I found out they pushed the caliper off centre. This meant I had to make up a spacer anyway so might as well have just made the whole adapter!

I reckon around a ton or slightly less would be doable.

what sort of power will the turbo give if I use the k26/8 parts you suggested wes. I have a new refurbished stock 924t item to fit, and the one fitted to the car atm which seems to be fine, but I will inspect it further tomorrow.

I have just had an hours chat with one of my friends who I did motorsport engineering course with. he has been building custom ecu setups and mapping them for 5 years now. he reckons he could get my engine up and running, and mapped for well under £1500, which tbh I think is very reasonable. and it puts me back into my comfort zone when it comes to tuning engines and fully understanding the process.

something to think about

The K26/8 from the later 951 is almost the same turbo as the one used on the 924 Carrera GTS (245hp@1bar) and also the 924 Carrera GTS Clubsport (anywhere between 270 and 320hp).

The main problem is the strange 3 bolt turbine housing on the 931 where it bolts to the exhaust manifold. This unfortunately limits options with off the shelf turbos and so you have to use a size 6 931 turbine housing (from S1 cars) or a rare as hens teeth 924GTS size 8 housing.
The size 6 housing reputedly chokes flow once you reach ~320hp. It is a good compromise though with the KKKs between response and power.

My own personal view is go standalone, especially if you're already used to that kind of thing. My current build will be the first time I've used a standalone ECU so it's all a steep learning curve for me and the engine is likely to be unrecognisable when it's finished, but I've fancied doing it since around 2005.
I only stumped up the courage when I realised my original engine needed basically a full rebuild.

There's a guy in Sweden running 384hp from one of these engines... since 2003... going balls-out on track. That engine has Verdi con rods, JE forged pistons, modified OEM head gasket with pyramid rings, big valve head completely gas-flowed, ITB's, standard exhaust manifold with a welded flange taking a Garrett GT30.... his next move is a new exhaust manifold with a Borg Warner 7670EFR. Oh yeah, he makes the 384hp@1.55bar so boost isn't huge by modern standards.
His engine made 180hp at only 0.3bar IIRC and 305hp@0.9bar which really is low boost for these engines when intercooled.

so what sort of power will the stock s2 turbo provide? at the sort of boost levels cast pistons can cope with!

I will likely run a 951 ic, with straight inlet into the front of the manifold, and I will also most likely fabricate a 3inch exhaust system and run a tial wastegate.

im getting carried away again, but I could fabricate a custom manifold and choose whichever turbo takes my fancy rather than running a kkk.

I think I would do that next time around, im thinking of getting the car running on standalone and the stock turbo. then once that's all done and proving reliable, think about fabricating a manifold and bigger turbo, along with some forged pistons etc.


while I remember, can stiffer gearbox mounts for the snailshell be found? or are the soft mounts soft for a reason? I also found the engine mount on the ex manifold side was buggered, and these are no longer available, so will be fitting some stiffer race mounts, either off the shelf or I will fabricate some.

just comparing the turbo fitted to the car, and the replacement I have.
part number of the one on the car is 5326 970 6022
the replacement has the same part number but 980 instead of 970 in the middle? the turbo plate is AET which I suppose is the company that rebuilt the turbo?

any info appreciated.