Silvia Club of NSW

G'day guys,

I have noticed that you guys gained some more boosy from upgrading your exhaust system. How do you do that? Did you have to remove or add something? Or is it like just happend? Coz I got my full exhaust replaced, but I am stuck with 6-7 psi only.


Cie

a cat back system saw no extra boost for my car. 7psi still
with a fitment of an air filter its still about the same. maybe a little at nights.

with a turbo back system, i often see 9psi at nights and a constant 8.5 during the day..

hope that helps

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Officer ! I swear its all factory standard.

after u fit turbo back exhaust u should gain 2-3psi boost.. my stock system was 7 psi and after exhaust and airfilter i'm now running 10 psi

Is your car an S15? If it is then its strange its not increasing the boost.
My S15 has got Apexi power intake, Trust Poer Extreme II zoost, CES dump pipe and is making 0.8 bar. In some very cold night it gets up to near 0.85 bar.
Note that at low revs the boost is pretty much same as standard but once past 4000rpm that boost will slowly rise up and by 6000rpm it will make 0.8 bar most of the time.

Yeah, I got an S15. I fit Power extreme II cat back and Liverpool cat, front and dump pipe (1 piece).
I tried reving slowy and also quickly and shift at 6000. Still nothing. Very strange huh? I asked Liverpool people, they said that the computer controls it. I will not gain any extra boost.

fitting a large exhaust allows your car to 'breath' better.. less restriction behind the turbine...

the turbine works via a massive pressure difference accross it, increase this pressure difference and it'll be able to spin faster and thus flow more exhaust..

run only a dump pipe and it'll be even wilder =) try it some day!

That's bull shit from Liverpool. The ECU on the S15 don't calibrate boost levels. Every person I know who got an S15 has benefited from zoost upgrade. Have you noticed any power increased from your seat of the pants experience? May be your boost gauge is not working? May be the Liverpool cat is causing air flow restiction bottleneck. The factory cat is actually very high flow so if I were you I will try to put the factory cat on and see if it brings out any differences.

you wont get any huge increases with just a exhaust, only around 2psi. if that was the case (huge increases) then why would we need ebc's, power intakes, retuned ecus etc...

to get the extra power everyone talks about for free, you need to remove the restrictor in the T piece. go here: http://www.200sx.org/faq_3.html and look for '3.18 What's this about a free boost upgrade?'
during cold nights you will experience boost spikes, but overall you should be getting good boost out of this cheapo jobbie. although dont rely on it forever, spikes are dangerous and if your serious look for a good ebc.

if your car is still not boosting then you might want to look at your turbo dump-pipe if its not restricting the turbo's internal wastegate in any way.

put into consideration the heat we've had too.
if your doin your power runs in the heat then less boost...


i agree with MYSilvia. you should get some sort of increase and livo might have their wires crossed.

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Officer ! I swear its all factory standard.

Whether it has anything to do with t h is or not I don't know, but the S14 and S15 computers do control boost.

In ROM edit there is a two full three dimensional extra maps for this, and the S14 and 15 are 512kb instead of 256kb like the S13.

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S13 Silvia Tuning - The Definitive SR20 Modifying Site

One thing to try if not already done is to remove the battery cables, push the brake to drain anything left and reattach battery cables. It basically resets the computer, so drive hard after this and see how the b00st goes.

I'll chuck in a few comments.

S14 and S15 ecu does control boost, to a certain extent anyway. They both have a boost map (S15 has a lot more resolution than the S14) but the primary boost control is the wastegate spring itself. The ecu cycles the boost solenoid bleeding air away from the wastegate however as it is an open loop control it does not look at what boost the car is actually running, it simply assumes the rest is standard. If you do anything to free up the restrictions behind the turbo you will get more boost as the ecu does not know this has happened. It's actually a good test for an exhaust, the less restriction in the exhaust the greater the boost (all else being equal) so therefore the best flowing exhaust will result in the highest boost increase.

Resting the comnputer won't impact boost control at all, those maps do not have the adjustment tables which are cleared when you reset the ecu.

A few more comments here:

I thought I'd mention what happened to me in this situation because its a bit different to everyone else's in terms of boost numbers. I've got a SR20 s13 and when it was dead stock I put a boost gauge in. The result was a fairly consistent 9psi in 3rd gear. In goes a custom 3in mandrel exhuast from Turbo Exhaust Centre and vwwaallah 10.5 - 11psi. This seems a bit more than everyone else got - especially when standard.

Any thoughts/comments?

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Signatureless

My car now has onlt catback exhaust and runs 9 psi spiking at 10 most times.

Very intersted to see what front mount intercooler does and then front/dump pipe...

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S13 Silvia Tuning - The Definitive SR20 Modifying Site

the dump pipe will increase your boost.
the FMIC will drop it by about 1-1.5psi due to less restriction.

if your running a bleed then there is nothing to worry about.

as for Silvia K inG getting those boost in standard for is either running a faulty BOOST guage or the engine is internally worked.

knowing these cars comming from japan the 2nd scenario sounds more realistic..

CMYS13 was getting the same and pulled 140kw@rw with just cat back...

damn...

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Officer ! I swear its all factory standard.