upping boost, stock internals, running lean - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

s14_mike · 09-30-2008, 11:27 AM

I need some help guys, I was lead to believe that a stock sr (mine is 98 s14 kouki sr) was capable of handling up to 15 psi of boost with stock internals.
So on to my predicament, I hooked up a manual boost controller, running it off of the vaccum line for the wastegate, then I hooked up a boost guage to find out how much psi i was running. The guage read 15 psi, however at high rpm maybe after 4.5k to 5k on the tach my car would lean out. Any answers as to why it might start leaning out towrds the higher rpm range?

Rnz520 · 09-30-2008, 11:32 AM

you are maxing out your injectors, put the boost down to 12 at most.

rc1honda · 09-30-2008, 12:16 PM

Yeah the injectors are at there max. I was told by people at the dyno that a SR with stock bottom end can handle more then 15psi. They said 18-20 psi is no problem if you got a good tune, and a metal head gasket.

SoSideways · 09-30-2008, 12:21 PM

Quote:

Originally Posted by s14_mike

I need some help guys, I was lead to believe that a stock sr (mine is 98 s14 kouki sr) was capable of handling up to 15 psi of boost with stock internals.
So on to my predicament, I hooked up a manual boost controller, running it off of the vaccum line for the wastegate, then I hooked up a boost guage to find out how much psi i was running. The guage read 15 psi, however at high rpm maybe after 4.5k to 5k on the tach my car would lean out. Any answers as to why it might start leaning out towrds the higher rpm range?

You forget to read the most important part of STOCK SR's WITH T25 CAN HANDLE UP TO 14/15PSI blah blah blah.

You have a T28.

What's the problem?

Operator error.

That's what the problem is.

QuickSpoolSR · 09-30-2008, 12:25 PM

you shouldnt go past 12psi with stock everything, why dont you go do some research

*njd07* · 09-30-2008, 12:27 PM

wow just wow. you need bigger injectors and a tune before going 15psi. I would not go over 10 psi without them. you need to do your research better.

Sileighty_85 · 09-30-2008, 03:18 PM

this may help more
http://zilvia.net/f/tech-talk/194503...injectors.html

G240 · 09-30-2008, 05:46 PM

Do you have an upgraded fuel pump? or an adjustable fuel pressure regulator?

renegade_ewok · 09-30-2008, 05:49 PM

Make sure you have a bigger fuel pump, bigger injectors, etc aka fuel mods and then crank up the boost. If you are sticking to a T28, 550cc injectors will serve you well.

majinraver1115 · 09-30-2008, 11:06 PM

thanks for the input fellas, i think i got it figured out now.

haha sorry on friends account

just realized and edited

09-30-2008, 11:27 AM	#1
s14_mike Zilvia Junkie Join Date: May 2007 Location: 626/Monterey Park Age: 36 Posts: 416 Trader Rating: (9) Feedback Score: 9 reviews	upping boost, stock internals, running lean I need some help guys, I was lead to believe that a stock sr (mine is 98 s14 kouki sr) was capable of handling up to 15 psi of boost with stock internals. So on to my predicament, I hooked up a manual boost controller, running it off of the vaccum line for the wastegate, then I hooked up a boost guage to find out how much psi i was running. The guage read 15 psi, however at high rpm maybe after 4.5k to 5k on the tach my car would lean out. Any answers as to why it might start leaning out towrds the higher rpm range?

09-30-2008, 11:32 AM	#2
Rnz520 Zilvia Junkie Join Date: Oct 2007 Location: Culpeper Age: 34 Posts: 388 Trader Rating: (0) Feedback Score: 0 reviews	you are maxing out your injectors, put the boost down to 12 at most. __________________ *93 240sx:KA-T, FLTA-2s, MR TR, Greddy F&R bars, Greddy gauges, Cusco brace, etc

09-30-2008, 12:27 PM	#6
njd07 Premium Member Join Date: Jan 2004 Location: canada Age: 38 Posts: 644 Trader Rating: (14) Feedback Score: 14 reviews	wow just wow. you need bigger injectors and a tune before going 15psi. I would not go over 10 psi without them. you need to do your research better. __________________ s13 parts fs:http://www.zilvia.net/f/showthread.php?t=193416 sr parts fs: http://www.zilvia.net/f/showthread.php?t=193399 s14 parts fs:http://www.zilvia.net/f/showthread.php?t=193420 180sx part out http://zilvia.net/f/showthread.php?t=203711

09-30-2008, 03:18 PM	#7
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	this may help more http://zilvia.net/f/tech-talk/194503...injectors.html __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

09-30-2008, 11:06 PM	#10
majinraver1115 Join Date: Feb 2007 Location: LA Posts: 41 Trader Rating: (0) Feedback Score: 0 reviews	thanks for the input fellas, i think i got it figured out now. haha sorry on friends account just realized and edited Last edited by majinraver1115; 09-30-2008 at 11:07 PM.. Reason: on friends acct

09-30-2008, 12:16 PM	#3
rc1honda Zilvia Junkie Join Date: Aug 2008 Location: Chicago Age: 42 Posts: 433 Trader Rating: (5) Feedback Score: 5 reviews	Yeah the injectors are at there max. I was told by people at the dyno that a SR with stock bottom end can handle more then 15psi. They said 18-20 psi is no problem if you got a good tune, and a metal head gasket.

09-30-2008, 12:25 PM	#5
QuickSpoolSR Zilvia Addict Join Date: Jul 2008 Location: des moines IA Age: 36 Posts: 756 Trader Rating: (8) Feedback Score: 8 reviews	you shouldnt go past 12psi with stock everything, why dont you go do some research

09-30-2008, 05:46 PM	#8
G240 Zilvia Junkie Join Date: Jan 2008 Location: Houston Posts: 349 Trader Rating: (5) Feedback Score: 5 reviews	Do you have an upgraded fuel pump? or an adjustable fuel pressure regulator?

09-30-2008, 05:49 PM	#9
renegade_ewok Zilvia Junkie Join Date: Oct 2007 Location: NYC Age: 36 Posts: 450 Trader Rating: (0) Feedback Score: 0 reviews	Make sure you have a bigger fuel pump, bigger injectors, etc aka fuel mods and then crank up the boost. If you are sticking to a T28, 550cc injectors will serve you well.