JE Pistons for 308GTSi listed 2 items for 81.5mm bore. Comp 9:1 or Comp 10:1 Both will require honing out from the worn 81mm stock bore to 81.5mm bore. The 9:1 pistons are close to stock. What would be the benefit or detraction of the 10:1 pistons? The new JE Pistons have a protection layer or indent on the skirt. Image Unavailable, Please Login
Our stock pistons are more like "Barely 8.0" at the point they stop below deck.. I would think the modern 9.1s would be noticeably "seat of the pants" better. 10.5 is traditionally restricted to premium fuel and engines with modern management. "In my day" that was considered about "full race" for the street These are the only ones made in the world for our engines, tell the "Thanks" for making them.
Sorry read your post too quickly. IMO the 10.1 would be streetable, not as bad as the old 10.5s. Probably be a real eye opener, but fuel and ignition advance have to be there too.
Wayne, You should call JE directly to make sure they have these readily available....or what the wait/backlog mfg time is. When I had JE pistons made for my blown 467 Chevy BB, I had to wait until race season ended because JE had a long line of custom pistons being made for racing engines. This situation could have changed since then; the last time I had a motor built with JEs was back in 2004. -stu
I do not have a 308 but know that also Woessner beside JE does pistons for them. Woessner is usaly very high quality Image Unavailable, Please Login
Thank you for feedback everyone. I will have to decide on honing out vs new liners from worn 81mm to 81.5mm
LA Sleeve (562) 945-7578 does 81 mm liners now. ( or 81.5) $ 165.00 each ,, what I paid ,, 9 years ago. ) ,, ( I sent them an old 1985 308 liner. )
I have had two, two valve cars with high compression pistons with ignition upgrades and, it made quite a difference. The injected car make 190 hp on a Dynojet....which is similar to a QV. I suspect most injected 2 valve cars are down around 170 hp or so at the rear wheels. That car had JE pistons. The other car is an early carburetor car with Woessner pistons. It made 220 hp at the rear wheels which is a little more hp than a 3.2 liter 4 valve car on the same dyno. Both cars were dynoed and tuned by ATS. I do mix in a gallon or so of leaded race fuel with a fillup, but both cars could probably get away with straight premium. One of the keys is being able to program a real advance curve, so in the rpm range when cylinder pressures are greatest, you can make sure you don't have too much advance and avoid knock. The injected car had an XDI which is pretty coarse. Yes the stock compression is really low. I tested an euro injected engine on a Whisler....and I think it showed less than 8.4-1.
Okay thank you for the great feedback. If I go from stk 81mm bore to 82 mm bore will the stock head gaskets still fit or do I need to find a special head gasket? I have had no trouble with Elring on past rebuilds. Just not certain about bore size compatibility.
Update - I ordered JE 10:1 - 81.5mm pistons, will be using stock cams. I had already had the digiplex units reworked to the euro spec. No air pump or cats on the car. 82 GTSi - Thank you to everyone for the input.....
