If I switch from NA to forced induction I would want that.

What my question is, can I run a 11.5:1 setup with a 62cc with a flat top piston and then find a dished piston that will drop compression to 8:1, is this even feasible?

I am not aware of how much compression you can take out with a dished piston, I don't know how much would have to be removed from a piston to do this?

 

with a flat top and a 40 th head gaktes you come in at just a touch over 11 to 1 zero deck height. if you were to switch to a 30 cc dish your just a hair over 8 to 1 part number ls2u512sd

 

so technically I can have the best of both worlds,

now my next question is whether the deep dish of the piston makes it abnormally weaker than those required for large chamber heads?

 

Goal, then not parts. Not vice versa.

 

i know this is an old thread an all, but i have a question. if i wanted to make 12.5:1 compression with a 59cc head, would a domed piston or lets say a -2cc dished piston be better? thanks in advance

 

anyone??

 

I thought I might as well chip in on this one........its been well known since the 1960's that big piston domes (some call them intruders) are bad news for combustion in both normally aspirated and turbo race motors......they seem to act like a knife to the flame front, leading to inefficient combustion, all motors that I have worked on with big piston domes have under performed big time, the best motors feature a shallow dome - if none .......this is why many manufacturers are now producing very small combustion chambers with minimal valve angles.

has anyone ever used coopers rings on a tuned LS engine?.......instead of the conventional head gasket?.........this would remove the volume created by the head gasket, and therefore make the dome/intruder significantly smaller.......they are simple - gas filled metal o-rings, that sit in a groove either machined in the the head, or block......its nothing new in a race engine application, and they dont cost a fortune...... we used them with great effect on the last IRL-Infiniti 3.5litre race motor (which never raced due to TWR going pop), and 2 litre 4 cylinder 500bhp turbo motors for rally cross in the UK.......

for example, say a 4" bore (101.6mm) with a gasket crush thickness of 1.5mm, that works out at a volume of 12.16cc by the headgasket only.......thats a significant amount of volume to be added to a dome........ok the piston valve cut-outs will need to go 1.5mm deeper but not 12.16cc deeper - still probably end up by knocking about 10cc off your dome volume.......you would obviously need to seal the waterjacket, copy the gasket choke points for the waterways, and sort the push-rod lengths.

whats the head gasket thickness on the LS range of engines?......I know many of the Multi Layer Steel (MLS) gaskets can now go very thin - 0.2mm (8 thou) on one engine I worked on - which may make it all a waste of time..........but if they are in the region of 1 to 1.5mm (40 to 60 thou) I'd say its well worth doing for a highly strung race motor