Cheburator

Thanks to all the listers for the advice!

It seems that drilling the crank is the way to go forward. I have found several engine building shops in the UK who can do it. I just did not feel like opening up what is a beautiful bottom end - it is only done 20k miles.

With regards to Bhp expectations - a stock GTS engine with bigger injectors, EZK and LH remap and cams, which are a half way house between S4 and GT, made 385Bhp on the crank. I would expect to see 400/410bhp on the crank with GT cams, 968 valves and proper headers from 928 International. I think I would go for 2.5" dual pipes all the way back...

Alex

Cheburator

It is a good thing that you cannot see it now - it looks like it has been kept close to a rather hot BBQ But I have already bought a new intake, wiring harness, cam cover, injectors, fuel lines, fuel pressure regulators and all that...

John Veninger

Yea, only if you have a special factory one off motor that has not been opened to see what was done......

That advice used on a stock 928 motor is a ticket with 928International's number to call for a new motor.

SwayBar

Alex, can you please list the rear wheel horsepower numbers instead? Quoting crank horsepower numbers means nothing since no one knows for sure which divisor was used against the numbers attained at the rear wheels from the chassis dyno. Unless of course, did you strap the block specifically onto an engine dyno and got a true number at the crank?

Cheburator

I would love to quote in common currency - RWHP, the problem is that often the dynos here in the UK will quote you "corrected" flywheel figures and not RWHP. When I had my GT dynoed, I had to specifically ask for RWHP, which came to 300...

It is annoying, but I only have the crank numbers for this particular GTS-engined car. I wanted to quote comparable numbers - apples with apples so to say

Alex

P.S. What happens if you use DynaPack dyno - http://www.dynapackusa.com/index.htmwhat number do you quote then?Wheel hub horse power?

mark kibort

I have 4 race cars and engines that beg to differ.
1. scots, already a full season of racing and running some of the faster times ever seen by a stock 928. (1:41s at laguna)
2. my old part euro, 2 full racing seasons and still running today
3. scots original 4.5 liter racer
4. my 4.7 original racer with 170,000miles and 3 years of obsessive track use.

I would be willing to bet the holbert car has nothing special done to it.

Mk

John Veninger

Must be that west coast Amsoil...

Cheburator

Oi! Kibort and Veninger, back on topic please!

John Veninger

OK, back to the topic.

As Gregg stated,
Drill the crank. Drill the crank. Drill the crank.

Cheburator

Well, looks like I will follow the advice and drill it - the pistons are coming out for the oil return holes, so I might as well drill the crank then and get the grove in the mains done at the same time...

Thanks

Cheburator

Just bought my 968 intake valves from Pelican for $14 each...
The money I saved will go towards drilling the crank

SwayBar

slate blue

With your 968 valves and bowl blend then tidy up the manifold, I posted some pics quite some time ago showing the end results of that, a great exhaust, I would use duel 3'' BTW like I have on my Euro with a bypass valve to keep it quite and torquey.

What about the cams? If you have new cams or near new cams take them out and get Piper to grind an old set, I have a set of 86.5 cams which don't need grinding but if you found somebody that had a set that did need some work you will then open up the breathing. Talking of dyno numbers I will dyno my car soon, the dyno has been broken for a month now, I got some figures yesterday but I don't trust them I wish I could as I have a peak torque of 505 ft lbs at 4500 rpm, while the torque is fantastic in this engine, it aint that good. I hope to do 340 rwhp.

Alex we are lucky that we have the same brand of Dyno that has a tamper proof system (controlled ramp rate etc)that is supposed to give results from machine to machine with a variance of 1%

Also have you thought about buying a set of 968 pistons and selling your GTS block and fitting the 968 pistons in a good thick S4 block? You would get good money for the block and it would make you some extra capacity around 5.8 litres.

Good Luck

Greg

Stan.Shaw@Excell.Net

I have two extra sets of 86 cams available

Cheburator

It is a race car - as long as it is below 105dB I don' t care for being quiet. Given that I am only running 5.4ltr, I am tempted to go to 2.5" dual pipe. I friend went to 3" on his Euro S2 5spd and lost the little torque he had low down...

I have a set of good GT cams which will go in, and I will also get the GTS cams reground to "sharper than GT" cams spec by piper.

No way - this is so much hassle, it is untrue. I have the last linered GTS block, which Porsche could supply, with 20k miles on it in perfect condition. Why would I want to sell it, then go through the trouble of finding good used 968 pistons as the new ones are expensive, then a decent S4 block, then a good machine shop who knows how to bore alusil... Nahhh... Too much pain vs. gain...

I have a goal of 400+bhp, which is achievable with valves, GT cams, exhaust and a JDS remap. This should be good to allow me to be competitive against the Aston Martin DB9 N24 in endurance racing - the N1 in class will always go to the ZakSpeed Viper... That is a beast, which even Mark A will have trouble with...

Alex