not holding full boost?? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

LOwrestling2001 · 02-01-2003, 05:11 PM

hi,
just finally got my 240 back s13 sr20 complete... and i have my profec B installed and what not. problem is at around 4-5 k rpms boost tapers off by like .1 bar...even w the profec B off so i'm guessing it's not the boost controller. ie (ebc off, i'll hit max boost like .5 bar or so, then around 4-5k rpms it starts to taper off a little down to .4 bar), same thing happens like if i turn the EBC on and raise boost to like .8 bar, the boost will taper off in the upper rpms to like .7 or .6 bar, wats the reason for this? i have an HKS SSQV, and i dont think it leaks boost, my guess is the actuator but i haven't had time to look at it yet, any other suggestions?

nrcooled · 02-01-2003, 06:59 PM

That is pretty much standard for turbos w/ internal actuator. It's just keeping you from spiking. The actuator opens and atempts to bleed off boost but it's not perfect. If it really bothers you get a better actuator from HKS but until then be happy your not spiking.

PS Is'nt 1bar fun as hell!

elevator · 02-01-2003, 09:30 PM

Quote:

Originally posted by nrcooled
PS Is'nt 1bar fun as hell!

I could get myself in a lot of trouble if I had no self control!!

...and yes that little bit of tapering off is quite normal.

LOwrestling2001 · 02-01-2003, 10:44 PM

so it's normal to bleed off like .1 bar? (like 1.47 psi)? just curious...thx

nrcooled · 02-02-2003, 08:21 AM

Quote:

Originally posted by LOwrestling2001
so it's normal to bleed off like .1 bar? (like 1.47 psi)? just curious...thx

Yes it is normal
This is what I do to combat it.
1. Set you boost to one psi higher than you want it
2. Then when it bleeds off it will sit at the level that you want

I have mine set to 15psi and I don't floor it in 1st and 2nd because it will spike (with the lightened flywheel) and 3rd-4th you will wax the a$$ of a few v8s that want a piece. Have fun and be safe!

TheSparo · 02-02-2003, 10:06 AM

what is spiking? and how does it occur?

02-01-2003, 05:11 PM	#1
LOwrestling2001 Leaky Injector Join Date: Dec 2002 Location: Bay Area Posts: 114 Trader Rating: (0) Feedback Score: 0 reviews	not holding full boost?? hi, just finally got my 240 back s13 sr20 complete... and i have my profec B installed and what not. problem is at around 4-5 k rpms boost tapers off by like .1 bar...even w the profec B off so i'm guessing it's not the boost controller. ie (ebc off, i'll hit max boost like .5 bar or so, then around 4-5k rpms it starts to taper off a little down to .4 bar), same thing happens like if i turn the EBC on and raise boost to like .8 bar, the boost will taper off in the upper rpms to like .7 or .6 bar, wats the reason for this? i have an HKS SSQV, and i dont think it leaks boost, my guess is the actuator but i haven't had time to look at it yet, any other suggestions?

02-01-2003, 06:59 PM	#2
nrcooled Nissanaholic! Join Date: Mar 2002 Location: Turn 8 'bout to get rolled by a SC'd ITR Age: 46 Posts: 1,849 Trader Rating: (0) Feedback Score: 0 reviews	That is pretty much standard for turbos w/ internal actuator. It's just keeping you from spiking. The actuator opens and atempts to bleed off boost but it's not perfect. If it really bothers you get a better actuator from HKS but until then be happy your not spiking. PS Is'nt 1bar fun as hell! __________________ '91 hatch w/ SR Sold; '03 Evo Sold 401 HP; '03 MS Protege sold; '00 Evo 6.5 TME Sold 300HP

02-01-2003, 10:44 PM	#4
LOwrestling2001 Leaky Injector Join Date: Dec 2002 Location: Bay Area Posts: 114 Trader Rating: (0) Feedback Score: 0 reviews	so it's normal to bleed off like .1 bar? (like 1.47 psi)? just curious...thx

02-02-2003, 10:06 AM	#6
TheSparo Zilvia FREAK! Join Date: Sep 2002 Location: Athens/Chattanooga/ Cookeville/Morristown, TN Age: 39 Posts: 1,141 Trader Rating: (0) Feedback Score: 0 reviews	what is spiking? and how does it occur?