Odd compression #'s

[pwayzjellyroll]

I had my mechanic do a compression test, he said the numbers all ranged from 190-195. It's the stock motor but has a head from a different 4g63t. The original head was ruined due to a timing belt jump. What should I look/for worry about here. Is it dangerous to consider upping my boost now? I did some searching but nothing to relevant to the boost question came up. I saw something about carbon build up, any links for fixed/solutions for that?

 

[hereitcomes]

190-195 is actually fantastic. 160 is around spec, so maybee you mistyped it? You want to be under 10 of 160 for near perfect compression. If you turn up your boost, remember to have supporting mods, and dont vent unless you have the propper set-up. good luck!

 

[Glliw]

That's very high compression numbers for a 1g. That sounds like an n/t motor, or at least n/t pistons to me.

 

[pwayzjellyroll]

190-195 is actually fantastic. 160 is around spec, so maybee you mistyped it? You want to be under 10 of 160 for near perfect compression. If you turn up your boost, remember to have supporting mods, and dont vent unless you have the propper set-up. good luck!

No they all actually read 190-195 according to him. I only plan to run 14lbs of boost so I think I should be ok. I have a high flow cat, 2.5" piping and an intake. I don't think I need fuel mods yet, but I could be wrong here.

That's very high compression numbers for a 1g. That sounds like an n/t motor, or at least n/t pistons to me.

I assure you it's a turbo motor and the stock pistons.

 

[Splitpi]

Possibly the type of head gasket and or decking of the new head decreased the size of the cylinder's slightly, thus causing higher compression.

Either way it looks fine to me. Just watch for knock and tune accordingly.

 

[nickheart]

uhh, my Haynes tear-down manual says 185 is the standard, i can't imagine how wear would cause HIGHER compression. I don' think that's a turbo head

 

[LordZed]

Possibly the type of head gasket and or decking of the new head decreased the size of the cylinder's slightly, thus causing higher compression.

Either way it looks fine to me. Just watch for knock and tune accordingly.

Thats what I was thinking too. Perhaps the head is literally closer to the pistons causing higher compression. Or a crap load of build up, but I doubt carbon would cause a number that high on a 1g. Just monitor you're motor and it should be fine. I can only wish my compression was that high. I mean mine is 135 across the board for a stock GVR-4 RS motor.....but it runs just dandy. I doubt you will experience any trouble. Especially at just 14 psi.

 

[Glliw]

Those pistons must have an inch thick of soot on them. 2g compression numbers are supposed to be 178psi I believe, and that's on a piston with way more compression ratio than a stock 1g.

 

[Cs4g63]

If those compression numbers are bothering badly enough than pull the head and check things out. Its always best to inspect things if you are worried about it. And all its going to take to make everything is okay is a days worth of work and some gaskets.