Outer Limits 4x4 Board

about to get the 4.2 td GQ tuned.

my mate that is tuning it runs 25psi in his comp truck


this car will be used in the bush and some tims on the road. it is not a daily car has 190K on the clock. my mate reckons 15psi.

wat boost do uses run and wat is ur opinions

thanks aaron

boost it up hi and have fun, more boost =more fun.

12ht wrote:boost it up hi and have fun, more boost =more fun.

haha i agree but i wouldnt like the motor to die in another 20k

Boost is relative to A/F ratio and EGT's

No point in running 25psi is you cant add enough fuel (a stock Nissan inj pump cant)

You cant run that pressure if the EGT's sit around the 600deg mark often. It will only last a few weeks like that.


With a proper setup with the correct run lengths and A/F ratios 15psi will give you more power than you need.

Our GQ runs 15-20 psi. Has a huge A-A cooler and water mist.

EGTs hit 600deg sometimes but this is a 100% offroad weapon

my old mans got a gu 4.2 td and he runs 14psi with 3inch zorst and it got dynode and has 146 hp at the rear wheels, iv herd if you go to hi you can start to have over heating isues to but if you stick to 14-15psi you shouldn't have a problem.

cheers scott

Z()LTAN wrote:Boost is relative to A/F ratio and EGT's

No point in running 25psi is you cant add enough fuel (a stock Nissan inj pump cant)

You cant run that pressure if the EGT's sit around the 600deg mark often. It will only last a few weeks like that.


With a proper setup with the correct run lengths and A/F ratios 15psi will give you more power than you need.

Our GQ runs 15-20 psi. Has a huge A-A cooler and water mist.

EGTs hit 600deg sometimes but this is a 100% offroad weapon

its is getting tuned properly. getting a boost gauge and egt gauge this week.

leaning towards 12 or 15 psi i think

it depends on what turbo you have, exhaust/dump size, is it intercooled.

also what year model the motor is series 2 gq motors are weaker than early gq and gu motors

with the right setup ive seen a gq do over 100000k on 25 psi making over 200hp n that was a second hand motor when it was turbod. have seen others run 15psi on crap setups and tunes and last 10000k

yeah, it really just goes to show you cant predict these things very accurately.

badger wrote:it depends on what turbo you have, exhaust/dump size, is it intercooled.

also what year model the motor is series 2 gq motors are weaker than early gq and gu motors

with the right setup ive seen a gq do over 100000k on 25 psi making over 200hp n that was a second hand motor when it was turbod. have seen others run 15psi on crap setups and tunes and last 10000k

its a denco Schwitze turbo, 3" dump 3" straight thru to the diff.its a 96 model not intercooled.

aaron

96 i wouldnt go far past 12 psi, and you may have issues with it getting hot, quite common in the later motors...

love ke70 wrote:96 i wouldnt go far past 12 psi, and you may have issues with it getting hot, quite common in the later motors...

wat boost are u running, have u got ur dyno results yet? did ur engine start getting too hot ?


cheers aaron

ive heard the pistons arent as good in the late model gq motors.

However saying that a mate in wa has a modded pump, roller bearing turbo and water to air intercooler and i believe he's running 25psi - 28psi...

or there abouts...

On my GU factory turbo since i got the 5k service it was running 15psi now i changed the setup and running 22psi its now done 10k all good ...

not yet mate, running 8psi at the moment with the gas, EGTs will hit 550 and happily sit at 450-500 with aircon on for 30 minutes through twisty country roads, temp got just over half way and stayed there, usually sit at a bit over a third.
i did however have my radiator cleaned and put fresh silicon oil in the viscous fan before doing the turbo to overcome any possible issues before they arose.

im gonna try get it booked in sometime soon to get it tuned, but working day to day, not being able to plan in advance makes it to book it in, and mechanics never wanna do stuff on th spot

ill make more of effort and let you know when its done.

love ke70 wrote:not yet mate, running 8psi at the moment with the gas, EGTs will hit 550 and happily sit at 450-500 with aircon on for 30 minutes through twisty country roads, temp got just over half way and stayed there, usually sit at a bit over a third.
i did however have my radiator cleaned and put fresh silicon oil in the viscous fan before doing the turbo to overcome any possible issues before they arose.

im gonna try get it booked in sometime soon to get it tuned, but working day to day, not being able to plan in advance makes it to book it in, and mechanics never wanna do stuff on th spot

ill make more of effort and let you know when its done.

cheers willl let u know how i go also.