Triaxle

iTrader: (1)

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?

oange ss

iTrader: (50)

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

Old Geezer

iTrader: (3)

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

69LT1Bird

iTrader: (1)

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.

Triaxle

iTrader: (1)

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.

69LT1Bird

iTrader: (1)

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.

Triaxle

iTrader: (1)

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

69LT1Bird

iTrader: (1)

You did check PTV, right?

Triaxle

iTrader: (1)

Haven't put heads on the block yet, but don't think I'll have any problems there. Still have a lot of chassis work to do.

Old Geezer

iTrader: (3)

As bird said....