So, it seems people keep referencing to 20psi on the previous posts about maximum boost on the stock turbo...375Hp or so...

Now lets hear it...What are you guys running for boost & Include your major mods list. (ie. Cams, Buschur FrontMount).

Is anyone running 22psi on there daily driver on 93? It just seems odd that everyone seems to back off at 20?

 

I think 20 or so PSI is the practical limit for the average fuel most are running.. and 22psi may be the limit of the Turbo's efficiency.. I think thats why you generally are seeing 20psi as the magic number.. I find that at 21psi its too close to the threshold of detonation with 94 octane fuel if you get bit of boost spike or weather change (with an MBC boost levels vary depending on weather)

This is only my personal experience working on these cars.. Others with upgraded hardware have run higher boost, but there are other things to keep in mind, nobody is really sure what the "Failure point" is for the USDM engine, IE Stock headbolts, etc.. and until there's some data on that, people are being generally conservative.

Also most of us still have some semblance of a warranty so many are keeping their mods conservative and reversable.

Unless your a HP Junkie, your much better off leaving your car stock (an Exhaust and Air filter upgrade is ok) until your no longer under warranty..

 

I run mine at 20-21 on 93 octane with no problem at all. With 100+ octane and no cat you could run 25-26 safely if the stock turbo will turn it. You will hear some people say the head studs are only good for 24PSI but that is a folk tale derived when someone didn't know what they were doing and blew their studs at 24 PSI. BOOST DOES NOT HURT A MOTOR! Detonation hurts a motor and as long as you are running a high enough octane to support it, you can run our cars at the max of what the stock turbo will produce.

 

Ok your answer filled in the blanks where I left off.. Good thing I didn't keep going.. He's right about 100 octane, but I haven't heard of any engine failures yet, and the circumstances of their failure (aside from a guy who nuked his motor with nitrous)

I haven't seen a turbo map for this turbo but I think that over 22psi your generating mainly heat and not much more pressure.. Since its a rotating assembly you have to wonder at what point the the moving parts in the turbo will fail, either stress failure or heat failure, or both..

Also Cams, Ignition timing, fuel system capacity, Fuel injector Duty Cycle, ECU, (ECU Fuel cut too) etc.. are all factors that could limit modifications to a more or less stock car.

 

Striktly.. I love that disclaimer..

 

Thanks. You are welcome to use it as well if you wish.

Also, what you said about the max boost on the turbo is right. I have toyed with the boost a little bit (please see disclaimer if you are Corp) and it doesnt seem to produce anything worth any HP over 22PSI. If you really want to run higher boost than that, you need to upgrade the turbo.

 

Well...then I guess ill run 21 psi daily

 

Just be cautious.. on a cool day you could get just enough extra air in there to cause detonation.. Honestly, 19.5psi is the safest bet and offers the biggest gains through redline.. 20-21psi is also fairly safe, but requires a bit more attention to tuning..

 

Damn...that sounds like a pain in the ***. I don't want to have to watch a datalogger everytime I drive But I have lots of mods sitting in a box, and I want to get the most out of them when I install them...

 

I took off my mbc cause my clutch is out and im takeing it to mitsu but it hit 25 psi once..... I dunno what the prob is my mbc was out when it happend.

 

ive been { read disclaimer} running 20 up to 22 posi of boost lately and it REALLY pushes. I dont want to run more than this on the stock motor though. Keep in mind i put 1 gallon of xylene in the gas tank to boost the octane to abour 94 octane. But onregular gas running 20 to redline its been doin well. the boost drops to about 18.5 by 7000 rpm.

 

It happened with the MBC or after you took it out? I once saw an overboost condition when downshifting a friends car because i had the MBC connected to the fittings at the turbo (inlet and outlet)

However if it happened after there could be a restriction or an air leak at or near your stock solenoid.. I know there's a restrictor in the line near the solenoid but I'm not certain if removing it would raise boost or lower boost (I think it lets the boost go higher) which could be the reason you saw an uncontrolled spike.

 

Did you find that the boost taper was the effect of the Diverter Valve?

 

Guys, keep in mind that boost pressure isn't the only thing that affects detonation. A freer flowing exhaust should flow a bit more air into the cylinder, which will affect detonation.

 

Good point..