Killert2

A friend notcie that i was only at 3.5 boost at 4k and i was wondering when would i hit full boost on an s4 turbo? My car stock only have emmissons removed

MmSadda

iTrader: (2)

It depends on how hard you depress the accelerator. Are you talking about being at WOT? We need specifics.

Killert2

Yes i mean at WOT and i was doing a pull and shifted at 4500rmp and my friend said i didnt go pass 3.5 psi

cmanns

Shift at the redline fool.

if you were in a high gear it'd spool up slower I'd assume dunno why your shifting at 4,500 doing a wot pull.

Killert2

hahaha i dont haha to redline to beat the honda around here but i'll give the redline a go but i thought u hit max boost at a lower rpm then a higher one

cmanns

I've never even driven a turbo'd car lol but as far as I understand car's hit boost more towards the redline.

The turbo spools up by the exhaust pressure, at low rpm's you'll have less exhaust output then at a higher rpm The quicker the exhaust can escape and spool up the turbo, the quicker you hit full boost.

I believe rx7's start spooling at 2.5-3k rpm or so

rotary-guy

iTrader: (24)

i can hit full boost by 3600 rpms, i have full exhaust though and running 13psi

Killert2

is everything else stock?

siguy2k

iTrader: (3)

yea you should be hitting more boost than that assuming your exhaust isnt clogged or something. My s5 stock turbo hit 6lbs(wastegate) by 26-700.

Killert2

Exhuast isnt clogged just had it off cleaned and replace the main cat with straight pipe

FrankV702

iTrader: (14)

Are you sure the boost gauge your using is accurate? Do you have any exhaust leaks?

arghx

iTrader: (3)

sounds like you may have a boost leak. A stock turbo can hit 6 or 7 pounds by like 3000rpm

Killert2

i do have a exhuast leak im just waiting for it to stop raining to fix it but i'll post what happens after

arghx

iTrader: (3)

well there are exhaust leaks but there are also boost leaks. That means bad gaskets, poorly fitting vacuum hose, poorly seated intercooler piping, loose clamps, etc. that makes a difference man. You really need to pressurize your intake to check for leaks. I highly recommend a tool similar to this: www.boostpro.net/prodtester.html . use it with a reducer to connect to your turbo inlet.