5kT perf. engine rebuild

[Ameer Antar]

So, my engine finally blew up. It was actually the hose to the heater 
valve, not the valve itself that broke. The engine overheated and when I 
poured water into the tank, I heard a scary thud from the engine. The next 
day, I looked into the hole and it was flooded w/ water. So is it likely 
the head is cracked, or could it be a blown gasket? Should I get a new head 
or can cracks be fixed?

Compression tests showed the rings were in OK shape. Should I overbore? If 
so, I was told by Rod at TPC that oversize pistons can only be ordered 
through the dealer. In that case, it'll be cheaper to have them custom 
made. You can get forged ones for $120 a piston. Forged pistons would be 
nice anyway as I'd like to warm up the engine a little more. My KH  engine 
has a few limitations in it b/c of the control system. The ECU is not 
programmable, so I'm stuck w/ it, unless I convert the whole engine bay 
over to '86-'88 5kT design. This means, my boost is limited to .4 bar, 
unless I use an aquarium valve, which I don't wanna do. I'd like to 
actually increase the compression a little, which would affect the 
performance throughout all ranges, not just at top end using higher boost. 
I have a ratio of 8.3:1 right now. How much could I get just from skimming 
the head? I could have the pistons machined w/ a smaller dish. Would a 
ratio of 8.6:1 be reasonably safe? Since my ECU can't be programmed, I was 
thinking of just retarding timing a few degrees. Can I do this just by 
turning the dist.? Please recommend any other good mods, that will warm 
things up a little. Thanks for the tips...