LQ4 to LQ9 pistons

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Mar 30, 2010 | 08:41 AM

Triaxle

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LQ4 to LQ9 pistons

I have a rebuilt LQ4 switched to LQ9 pistons and cam. I'm a noob with fuel injection systems and how they work. Is the LQ4 calibration going to be ok with the changes until I get a new tune? Or am I better off getting an LQ9 computer to start out with?

Mar 30, 2010 | 09:27 AM

oange ss

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fuel and spark requirements will change with the increase in compression and cam change, you need a real tune for the new setup

Mar 30, 2010 | 10:47 AM

Old Geezer

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Aren't LQ4 and LQ9 cams are the same specs...

Mar 30, 2010 | 10:51 AM

69LT1Bird

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The only difference is the compression ratio, a .5 bump up for the flat tops. Don't sweat it, you will be fine with the LQ4 PCM and calibration.

Mar 30, 2010 | 10:55 AM

Triaxle

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Quote:

Originally Posted by Old Geezer

Aren't LQ4 and LQ9 cams are the same specs...

Sorry wasn't specific there, I actually have an aftermarket cam.
Alright the compression bump was what I really wasn't sure about. Thats makes things a lot simpler.

Mar 30, 2010 | 10:58 AM

69LT1Bird

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Well that changes things. The compression ratio won't be the issue but the cam swap could be.

It should start and run, how good, hard too tell. I would take it easy until it gets tuned.

Mar 30, 2010 | 11:03 AM

Triaxle

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Quote:

Originally Posted by 69LT1Bird

Well that changes things. The compression ratio won't be the issue but the cam swap could be.

It should start and run, how good, hard too tell. I would take it easy until it gets tuned.

Alright thats my plan. I have a 228R right now a friend gave me, but I think I want to have a custom cam made. Thanks for the input