Got the ol' L28 out

This is what I came across..

This is cylinder and piston number 2 which is the worst I've found:





^You can tell where the head gasket got hot and deformed. (cylinders 1 and 2 only) Btw the surface rust is from having it sit without a head.


And this is the 2nd worst piston:



I'm going to have the block checked and if its OK, either have it honed or bored.

Should I go with JE custom pistons or ROSS?

That sounds expensive, any shelf piston kits around?

 

I've decided I should go with 87mm forged flattop pistons. One question is how much different will 8:1compression ratio be compared to 8:75:1? That is the difference between 87mm flattops and a 2mm headgasket and a 1mm gasket..

I would like the higher ratio but dunno about the 1mm with high boost later on.

 

8.75 will really make it fly at boost. You're going to use ARP head studs, right?

 

ARP headstuds and ARP rod bolts as well.

I would like the high compression but is the HKS 1mm headgasket safe for let's say...oh idk.. 20psi maybe a little more? (For in the future)

^With an aftermarket ecu and a dyno tune of course.

 

Yep. I've got a 2mm MLS headgasket, cylinder head shaved .020", 5 angle valve grind, 87mm Nismo turbo pistons, ARP head studs, 8mm rod bolts, magnafluxed rods, balanced crank, and other crap. I'm at 7.4:1 CR which lags a bit until boost. I usually run 10psi, 12 when racing (using intercooler and 300cc injectors).

Just remember that as boost increases, so does compression ratio. At 20psi, you'd be at about 20:1 CR. Hope the engine can handle that.

Play with this: https://www.rbracing-rsr.com/compression.htm