if i were to raise the compression on my 86 5ktq to 8.5 to 1 or use a JT block and head would this affect the computer adversly. Would ignition map not be able to keep up and would the engine knock. I know this is a very broad question, i searched the archive and couldnt find much info. So i thought i would throw this question out there. Just looking to cut down on turbo lag. Anyone who has any input, i would apreciate it.
thanks

If all your looking to do is cut down on turbo lag, just buy a used k24 turbo. They spool awesome but they cant flow a high CFM's all the way to redline. I was hitting 20 psi at 2700 rpm's, but the boost would start fall to 17-18 in the higher revs. I spun the **** out of my K24 for quite some time. I'm set at 18 psi now and it feels just the same as 22 psi did with this turbo.

Cheapest easiest way to get rid of turbo lag on that car would be to swap out the K26 and throw in a K24. direct bolt on. You can get one used for around $100-$150.

There's people running MC2 blocks(8:3:1) with Mac 11 systems without much drama.

Steve
Michigan

If you're running an essentially stock 5k motor, using a smaller turbo (the K24) would be much more financially efficient, I believe. The K24 should last your whole rev range if youre running on or below 1.8 bar... and probably even higher then that with just a little drop at the top.

talking only lag?

at the lower end of RPM range anyway. I, myself don't drive any where near redline. The engine is screaming at 4000, but even at highway speeds, you're only near 3000 and that's where you would want to have passing power or hill climbing on twisty, turning backroads.

the lag is so little its hardly noticeable when compared to any other turbo.