how much boost on stock turbo

[MikeGsT69]

how much boost can a stock turbo hold if i were to get a bigger fuel pump

 

[Bjeezy01]

On the T25, you can prob. hold around 20-23psi TOPS. But just becouse you get a bigger fuel pump, don't think you can just turn up the boost. With the stock injectors on the car you don't wan't to go above 18-19psi. Plus, keep in mind that the stock 2g BOV leaks after 9psi, so turning up the boost takes a lot more then just spinning the nob. But if your car has more of the mods, ya, you can safely push 20psi, and just slowly go try going up. But 23psi is on the boarder line with it. Your better off just buying a T28 and getting that power.

 

[MikeGsT69]

i got a turbo xs bov type h which i think is crap i got air filter and turbo back i fugured it would be cheaper to buy a fuel pump injectors and afc for know then get the turbo upgrade when i got more money or when i blow the t25

 

[Bjeezy01]

Well, youve got a good start. Do you just have an air filter? or a whole intake? Anyway, you are going to need a boost controller to controll your settings. But be carfull, yes that fuel pump will flow more fuel, but the stock rail and injectors can only do so much. When you are day to day driving you might wana keep it turned down. That BOV is alright, but a lot more then just the BOV leaks. You might wana look into getting new pipes, the upper IC pipe at the least. I noticed a large jump when I went to the aluminum piping. And also remember that the stock Intercooler can only hold/cool so much, and the MAF can only read so much. Like I said before, turning up the boost is not nearly as easy as people think it is. You might be better off doing this in stages, and working your way off. Sure you might upgrade your turbo when the old one blows, but you don't want that old one blowing on your way to work. Also if you do an turbo upgrade, you can re-sell the stock turbo and get some money out of it. A good 300+ for a good condition T25. I would recoment reading through in more depth before you turn it up. I have seen a lot of engines blow becouse of people turning up the boost. Dont always think only the turbo will go out and a high PSI, you can destroy the block/or/head too....

 

[MikeGsT69]

i understand u can blow ur engine by turning up ur boost and not haveing the right set up but i was wondering what i would have to do to boost it up to like 17 18 pounds without messing anything up

 

[Defiant]

Pretty much what everyone else has been doing for the last fifteen years:

http://www.dsmtuners.com/tuning-guide/

 

[eclipse98gs-t]

On the T25, you can prob. hold around 20-23psi TOPS.

What??????
Stock T25 just holds 16 psi max...
Maybe T28 holds 20 psi
Is this correct?

 

[rarson]

You will not be able to "hold" anything greater than 15 psi past 5500 rpm. This is because the stock exhaust housing is so small, the turbo becomes such a restriction at that point that no amount of wastegate control can force the thing to hold more than that much boost. Just try disconnecting the wastegate entirely, rolling on the throttle to 5500, and then punching it.

The T-25 is not efficient past 15 psi, period. If you try running it higher than that, you are a moron. Seriously, you will make less power. It's simple really, just practical application of the Ideal Gas Law.

Also, you don't need a fuel pump or injectors to run that high anyway. Once my wastegate accidentally got disconnected and I saw 25 psi... didn't even hit fuel cut.

 

[GSX_RCR]

You will not be able to "hold" anything greater than 15 psi past 5500 rpm. This is because the stock exhaust housing is so small, the turbo becomes such a restriction at that point that no amount of wastegate control can force the thing to hold more than that much boost. Just try disconnecting the wastegate entirely, rolling on the throttle to 5500, and then punching it.

Disconnecting the WG will revert your boost levels back to the WG's spring load, which if it's stock is like 9psi.

BTW, a "restrictive" exhaust flow will actually induce boost creep, not limit your boost levels.

But boosting a turbo past it's efficiency range will only heat up your intake temperatures and eventually lead to detonation and all sorts of bad heebeegeebeez.

 

[rarson]

Disconnecting the WG will revert your boost levels back to the WG's spring load, which if it's stock is like 9psi.

No, that would be the result of if you just hooked the boost source up to the diaphragm with no controller in between. If you disconnect the WG then you will get boost until one of two things happens: the flapper door gets blown open by exhaust manifold pressure, or something breaks. Try disconnecting the wastegate; like I said, I've seen what will happen.

BTW, a "restrictive" exhaust flow will actually induce boost creep, not limit your boost levels.

Boost creep is caused by a lack of restriction on the outlet side of the turbine wheel. The greater the differential pressure across the turbine the faster the turbine will spin. If the restriction is in the wastegate passage, then yes, boost creep will follow. But if the turbine housing itself is too small, there's no way you're going to be able to flow enough air through it to actually spin the turbine fast enough. The pressure differential causes flow, but since the housing is so small, the headloss across the turbine is so great and overcomes the effect of d/p.

Of course, that tiny compressor wheel isn't flowing that much air anyway, so that's likely another reason why boost levels are limited (exhaust pressure will be high but not significantly high due to the limited air entering the engine).

But boosting a turbo past it's efficiency range will only heat up your intake temperatures and eventually lead to detonation and all sorts of bad heebeegeebeez.

Yeah. And with the air that hot, you're probably going to loose power anyway (not to mention timing due to detonation).