Aftermarket Pistons to clear high lift cams

[evopwr]

Are there any issues when chosing high compression (10:1) aftermarket pistons in conjunction with high lift cams (280°) ?

Any manufacturers known to have interference, or manufacturers known to accommodate for this?

Application is 4G63 7bolt.

Currently considering MAHLE due to material construction (tighter piston/wall clearances).

Thanks
Alex

 

[4piknup]

You need to check it as you assemble engine.
Or its like jumping off a cliff without a parachute and hoping for a updraft to save you.

Its a interferance engine. It will hit. Depends on cam timing.

 

[evopwr]

Hmm considering how many built '63s there are I thought there would be an 'ideal' combo.

 

[4piknup]

I dont think bc280 are really considered 'high lift' cams considering kelfords have more lift on much shorter cams.
If you spoke to kelfords and asked what 10:1 pistons you can run without hitting, he might have some idea of the possible cam timing you could run.

I have the wiseco and cams are a 280bc exhaust and a cosworth s3 intake. I will be prechecking them both.

 

[DOUGMO]

Are there any issues when chosing high compression (10:1) aftermarket pistons in conjunction with high lift cams (280°) ?

Any manufacturers known to have interference, or manufacturers known to accommodate for this?

Application is 4G63 7bolt.

Currently considering MAHLE due to material construction (tighter piston/wall clearances).

Thanks
Alex

whats the lift on the cams? 10.5?


also what ptb are you thinking?

 

[evopwr]

George, 11,70 and sorry for the noob question but whats PTB an acronym for?

 

[DOUGMO]

piston to bore, 11.7 is decent lift

 

[EVO-00X]

Most brands make a 10:1 for a 4G63 mate. That's what you would use for a dedicated E85 engine, maybe you might even want to go even higher CR if you really wanted to, but it is a road car and you want to have a little more headroom for shitty fuel. Are you planning on going flexfuel sensor to mix 98 and E85?
CP seem to be more widely available and reasonably priced compared to JE's.
In which case you would want the CP piston part number SC7321 for an 85mm bore, or the SC7322 for a 85.5mm bore for the EVO I-III engine.
But in any regards, you need to have your engine builder check valve to piston clearance and determine what headgasket thickness you will need too because who knows if your head has been shaved or the block deck has been reduced in the engine's lifetime.

 

[DOUGMO]

I went for a lower comp piston and took a heap off the deck to get the piston coming closer to the head (ideally around 30thou, maybe 40 for a street engine)

my pistons come out of the top of the block 7 thou and I run a 1mm gasket

 

[evopwr]

George, PTB as tight as possible lol!

 

[blackvr]

I think you will find the valve pockets are the same whether it is a 10.0 or 9.0 :1 piston. The only real difference between the compression spec pistons is that the 10.0s have a "flat top" and the 9.0 have a dish in the piston crown. I've built several of each, and haven't had issues... again, the engine builder has the responsibility of checking clearances !