S2 SPS cylinder head

[Peter Empson]

I thought I'd start a thread to share my experiences with my new SPS built cylinder head (responsible for Paul's 3.2L beasty).

I've only down about 150 miles so far but the improvements are quite surprising and very welcome.

First thing is how much smoother the engine is at all revs, I'd never have described the engine as rough before, but it is a lot more refined now.

It also has a huge amount of extra torque low down, you can drive around town at RPM's that were quite impossible before. It's so much easier to drive in traffic and you don't have to change down so often.

The extra torque shows itself again when driving it properly, the engine picks up with more vigour and the 4K kick seems to have started coming in at closer to 3.5K or less.

The funny thing is that none of the above were areas that I've criticised the S2 engine for before. Where I have always felt it was lacking was its top end, which felt a little undramatic and flat for a 16v. The new cylinder head has gone a long way to resolving this, the power delivery is now far more linear and potent. There's none of that feeling that the engine would rather I gave it an early up change, and taking it to over 6K is now a worthwhile and far more pleasurable exercise.

I know S2 heads (like 968's) are prone to heavy valve seat wear, and so how much of the improvements I have seen are due to it being a fresh, and how much is due to Simon's skill and modifications I cannot say with absolute certainty, but I can't help feeling the latter is responsible for most of the gains seen.

This really is one of the most impressive things I've had done to the car and would now rate its importance as top of the list for anyone looking for power gains on their S2.

For the record my car made 215 bhp before so seemed pretty healthy with 150K miles on it. The cylinder head was the only change made at this time. I'm itching to get it on the dyno to see if the perceived improvements are as clearly visible as I expect, if only WRC were still going strong.

As well as Simon I must thank the guys at RPM Porsche again for fitting it for me at short notice and turning it around in just 2 days. The car would have made it to Silverstone as planned if some plonker ([]) hadn't cracked the windscreen beforehand. In fact since I'm thanking people, RPM recommended Fleet Motor glass (01525 375 050) who did a great job with the screen and only charged £645 to my insurers which seemed very reasonable to me for such a tricky job).

 

[andymorris]

Hi Peter
Thanks for your old head - cheque is with the boys at RPM.
So could I get this work carried out on your old one. Subject to wether my insurers will cough up for my engine fire!
Mind you having been for a burn with Ollie in the Silver Rose Turbo they have Im very tempted to try and get them to do me a deal.
Regards
Andy

 

[Peter Empson]

Hi Andy,
I was sorry to hear of your problems, I'm dropping the head off at RPM first thing tomorrow morning, I'm glad it's going to a good home. With all the work you've done on your car it'd be a great shame not to see the benefits, and the last thing we need is another one defecting to the darkside of boost []

As for having the same thing done with my old head, well I can certainly recommend it (and I think that head is probably a much nicer starting point than the one I used). Simon said the normal turn around is circa 10 days, and the cost doesn't add that much considering you may as well do it right whilst you're in there.

If you want a drive of my car before deciding just give me a shout and try it for yourself.

Best regards,
Peter

 

[andymorris]

Peter
I was amazed by the dark side of 'boost' and now i understand why some can easily be caught out by it.
With the money Ive spent I still want to keep perservering with it and Im hopeful one day soon it may start spending more time with me than with ollie. Although the crack in the head sprayed oil everywhere which ignited on the manifold I think that maybe sooner or later the head gasket would have needed to be replaced and so on the bright side its just another job done and if the BHP can be increased then great.
Thats a kind offer and I may take you up on the drive. I should know in a week or so what its going to cost and how much the insurers will contribute so I will keep you posted.
Thanks again
Andy

 

[333pg333]

Hi Peter,
Good to hear such positive news from your freshen up. Do you actually know what work was carried out on your head? Just curious.

Patrick

 

[Peter Empson]

Hi Patrick,
I do have a list of what Simon did, but I don't think I should divulge it just in case there are elements he'd rather not let his competitors know about. If Simon is happy to comment then I'm sure he'll post accordingly.
Best regards,
Peter

 

[333pg333]

Yes absolutely fair enough. I guess I meant just generic things like cams, changing valve sizes or springs or porting/polishing more so than proprietary secrets. I am dealing with a similar thing and I totally understand the requirement of keeping certain things schtum. Hopefully Simon may comment just as a point of learning.[]

 

[edh]

Sounds great Peter - put me down for a ride at Silverstone

 

[charles.y]

Peter,

Just wonder how much the mod costs?

 

[zcacogp]

Sounds very interesting ... my questions morror Charles' and Patrick's. Given that the S2 seems to be almost un-tunable (without mega-money superchargers and the like), this sounds like an interesting development.


Oli.

 

[Peter Empson]

The SPS head work cost £750 (but the spare head I supplied did need quite a bit of work as it was fairly well worn, so prices will naturally vary). Considering Simon's attention to detail I think this seemed very reasonable. For reference the labour to swap the heads over, do belts/chains, fit new water pump and so on came to about £1,500 ish.

The cams are original, there aren't that many alternatives available and I wasn't convinced that they are the right way to go for a road car (I didn't really want to raise the idle speed for example), plus adding the cost of another mapping session meant they ultimately became quite expensive for an unknown gain.

Preferring to be pessimistic with these things I was quite prepared not to see much difference with the head work. Many years ago I had my old 8v head polished and ported by a local garage and it made such a small difference I often wondered if I was imagining it. This definately isn't the case with the SPS 16v.

I'm itching to get it on the track, and as soon as Melindi has called me back I'll be booking the 7th of August []

I also had RPM move the rear ARB to full hard (the car's a bit too low for me to get underneath it myself []) with the hope that it will cure the high speed understeer, if that works (and it certainly has changed the car on the road at low speed) then I think I might up the rear spring rates as I suspect that this may be the cause. Whatever it is though, it'll be fun finding out []

 

[333pg333]

Peter, I've only just noticed that you're running a carbon hood. Any details as to costs and where you got it? Also we have just bought an LHD S2 so will be turning it into a track only car. We are toying with what engine to put in it and for the moment look like we're going to stick with the n/a configuration. Just as a matter of interest there are more mods that you can do like cams and high compression pistons, but they do come at a cost. If you, or anyone else is interested for n/a or turbo applications I would recommend talking to Dave McGrath / Evil 944 if curiosity strikes.

Patrick

 

[Peter Empson]

Hi Patrick,
Here's a link a thread about my bonnet: http://www.porscheclubgbforum.com/tm.asp?m=259620&mpage=1&key=𿘤
Your track car sounds very interesting, please keep us updated about its progress.
Best regards,
Peter

 

[333pg333]

Thanks Peter. That looks interesting. We had a guy here who started to make us a c/f hood but for one reason or another things went pear shaped which was a pity as he was quoting about 4kgs? I would be looking for one that I could change over from road car to race, depending on which one we race that weekend. (If not both) Same with the lexan rear hatch. Should be pretty interchangeable and not something that will last in our Sun if used every day on the road car. As for the race car, well really not sure what we're going to do, but running it as an n/a racer should be a good intro to an LHD car. We can decide what to do later with it if we go racing seriously. I am still toying with the idea of a 3.4 16v turbo beasty but that may wind up in the road car for a while if we run the S2 as n/a. All a steep learning curve.[]