Just needing a sanity check here..

I bought a brand new GM L05 short block from SD. It has 4 bolt mains, cast crank, -18cc dished cast pistons & stock deck height 9.025".

I am trying to confirm some measurements so like i said, just needing a sanity check. Here are the pics of me measuring piston to deck height, i zero'd out the gauge on the block then carefully moved it to the edge of the piston, this showed .025" difference right?

Also want to check my CR calculations.. I have a brand new set of trickflow heads with 62cc chambers. i plan on using a 4.1" bore, .015" thick head gasket (I know this is thin but I have read people have had many good results with this and I have all brand new components so my surfaces should be level) - this should give me a 0.04" quench height. With my stock 4" bore and 3.48" stroke, i should be making 9.1:1 CR right?

Thanks guys, just wanting someone to double check my thinking for me.

Thanks,
Richard.

 

I'm coming up with 9.1126:1 Yes, it's safe to run those gaskets with your pistons that far in the hole. It's what I do. For myself and most of my customers. Note: new heads, fresh out of the box, need to be checked with a long machinist's straightedge. The machining was done while the heads were still hot from the casting, and the heads cool in the boxes. If they're not perfect, a light shave to remedy it will put you at like 9.2:1, still pretty low. Are you planning on running a supercharger or turbocharging?

 

It just hit me what's bothering me. And it isn't boost with cast pistons. I think those pistons look like 12 cc, which would be good for non-boost. Closer to 9.7:1 or 9.8:1.

 

Cool, thanks!

Not planning on running any power adders for the time being. My plan down the road is to either go supercharged or or a full rebuild with a stroker crank, flat tops and an HSR. Might just get the HSR in the interim

With aluminium heads, will 9.1:1 CR be enough? The cam has a pretty mild duration and lift should be just below 0.5" - it is an LT1 cam.

I know "enough" is subjective, just want to confirm it wont be a complete dog

 

I'm at 4500' elev. and up here, 140 psi of cranking compression is the line between driveable and do something. If you're too low, change the cam. That cam was intended for a 10.4:1 engine, but on the other hand, it's perfectly happy running down the interstate at 1450 rpm @ 65 mph. The RamJet 350 cam can be had new for under $150, and it's excellent at building torque from 1000 to 5000 rpm, but I know the ZZ4 cranks around 200-205 psi @ sea level, and is better from 3500-5800 than the RJ. This cam can also be had for cheap. But the LT1 cam is perfectly happy twisting to 6200 rpm. Another option is just change to a higher-stall torque converter. This costs more than a cam, but has more potential.

 

I will be running a T-56 manual. My biggest limiting factor for RPM will be the TPI intake.

 

An HSR would solve that.

 

Yeah, that would be nice! Gonna have to stick with TPI for the time being.. My project budget is already well overspent! Gonna do some gasket matching on the intake though, should clean up the airflow some.

9.1:1 should be ok even with aluminium heads though right? I should be producing as much power as a stock L98 right?

 

It'll drive, and even if it does feel "doggy", that doesn't hurt anything but your feelings, if that. Well, it does hurt acceleration, but boo hoo, right?