Euro spec pistons - worth the expense?

Nathan M · Nathan M's Garage

Is it worth converting my 3.2 (930/25) to Euro spec compression while it's in bits? My existing P&C's are perfect and well within spec. I can buy used (good) 10.3/1 Euro pistons for £400 in the UK. Would this be a worthwhile move, or could I get the same inprovement from (used) 964 cams at half the cost? (or should I go the whole hog and do both?!)

1fastredsc · 11-20-2003, 05:31 AM

(bad influence) Do them both.

makaio · 11-20-2003, 05:46 AM

I agree! Do them both.

Rot 911 · 11-20-2003, 05:50 AM

Do them both as long as you can get high octane gas needed for the compression increase.

Early_S_Man · 11-20-2003, 06:38 AM

Nathan,

Considering the lack of a knock sensor on the 3.2 ... and the trend toward lower octane levels in gasoline, I suggest NOT doing the pistons! Detonation is a nasty thing to deal with ... and could hasten the need for further repairs in short order! Put the money into a set of Web-Cam 20/21 grind cams and enjoy torque and power benefits for another 100K+ miles!!!

Even a 964 engine with knock sensor isn't immune from damage if you aren't careful ... as the following thread shows:

Ouch, what could cause damage like this so quickly

rpiper · 11-20-2003, 07:14 AM

I agree with Warren. Keep your pistons and go with the 20/21 or 964 cams, a chip and some SSIs. Detonation is a constant problem for my SC with 9.8:1 CR Euro P/Cs. I really have to be careful with the gas I put in, especially if it's hot. Runs great with 110 though!!

dd74 · 11-20-2003, 07:44 AM

I wouldn't increase the compression. High octane gas is becoming increasingly difficult to find. Unless you want to mix race gas with standard pump gas, or experiment with octane boost, etc.

964s, a good chip and exhaust should get you a good amount of hp. Maybe 240 hp or so.

fintstone · fintstone's Garage

If you use the car on the street as a driver, keep the compression lower (9.5:1) due to fuel availability and reliability (you already have the potential weakness of the longer stroke). Instead, buy SSIs, lighter weight, forged JE pistons and have current cams reground by webcam. Then sell current pistons to recoup the difference in cost.

1fastredsc · 11-20-2003, 08:22 AM

I thought europe has better fuel qualities (he's in england).

movin · 11-20-2003, 09:44 AM

You can use the Euro Spec pistons, but in doing so you should do the twin plug conversion, that should solve the detonation problem by allowing a chip reprogram to reduce max. ignition advance and still achieve better performance. Although, it's less expensive to do what is mentioned above and get the same performance increase.

Nathan M · Nathan M's Garage

Yes I'm in England and we have a plentiful supply of 98RON fuel (not sure how this translates). All the UK 3.2s have the high comp pistons as standard, but mine was a Swiss import with the US spec motor. I'm not aware of any detonation problems over here with the 10.3 pistons, but maybe there's less increase to be had with a custom remap with 10.3/1 pistons as the map has to be more conservative?? What do you think?

I've recently purchased a stainless Euro pre-silencer & sports exhaust so SSI's not an option at the moment (maybe some day!). I do the odd track day and struggle on the straights against the more modern stuff, which is why I have the need for more oomph! The car is mostly used on the roads though, so weight reduction will be difficult as family outings are usually taken in the Pcar.

Alan.UK · 11-20-2003, 12:48 PM

Hi Nathan,

What you are doing is my next plan. For one reason or another I am selling the 3.6 motor I have and probably doing the 3.0 or maybe a 3.2 ltr conversion as I have the SS exhuast set up and a set of webers already. The extra CR is worth some addtional HP and if thats what your after then why not. Dentonation should not be to to much of a problem as there are plenty of 3.2 (euro) car owners over here with no problems.

Alan.UK