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Hello everyone. I need advice in choosing the correct pistons . I'm in the process of building aturbocharged 1326cc bigblock engine. I'm using a kz1000 bottom end with a 1984 gpz1100 cylinder head. I know that with the bath tub gpz1100 cylinder head it will drop the compression ratio 2 points. I want a comp. ratio of 8.5 I have been told to use a kz 10.5 ratio piston to make it out to 8.5 with the gpz1100 head, but i was wondering if the kz piston would match up with the gpz1100 combustion chamber ?
Experienced knowledge needed please.
I think that the APE site has that info.
I would do just what your doing. 10.5 KZ with 0 deck height and the eng will run good. How much boost are you planning on using?
I would think that using a 10.5 comp kz1000 piston would not work with the 83-84 gpz1100 bath tub combustion chamber. The max boost pressure i will run will be around 20 lbs. I was thinking that the gpz1100 valve angle would be different than the valve relief cuts in a kz1000 piston dome. : / Something has to work as i see alot of J model and gpz heads on kz1000 lower ends. I thought of using a gpz1100 turbo piston with a spacer but from what i see available they are all 18mm piston pins.
I built very close to that. Use a flat top piston,Zero deck height, GPZ head machined .060 and port it. About .384 cam with 260 duration or more, good springs. It'll rip with 25 psi boost, drawthru. KZ piston with bumpswon't work on that head without domes done. Be sure to do all the other usualengine/case mods to support the power.
Thanks so much ALO ! Whatthickness do you recommend for the base gasket and thecopper head gasket ?
The deal is no one can answer is how much was the cylinder decked to make the 1325 bore size.<div></div><div>Some big blocks were actually long on purpose so to not need a base gasket,just Yamabond like the case.</div><div></div><div>In any case the base gasket thickness is to "adjust" to get the piston to zero deck. You then need .040" head gasket tp prevent head contact with rod stretch.</div><div></div><div>Cometiccan CNC water jet cut cut any gasket,any thickness,any quantity.</div>
I really appreciate the advice SONICRETE. You guy's have been alot of help. : )
<DIV>Originally Posted by GAGE
<DIV>I put a .020 copper base gasket in to get zero deck on the pistons but you need to measure it for yourself. And the standard .040 head gasket. Would be worth putting a receiver groove in the head for the O-ring. I blew a couple gaskets before doing that.</DIV></DIV>
the GPZ head has a diffrent valve angle so the pistons need to be recut for the diffrent angle. I had to do that with KZ flat top pistons.the cam I use doesnt have much lift and they just touched when I didput it together to check forclearance, had to cut new valve pockets for it to work.
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