Question about boosting the 4g63

[Drewcool2]

I have a couple questions...
I've been searching around the forums but I can't find consistent answers anywhere.

What is the MOST boost you can run safely through the stock internals/fuel system on the 4g63 (ignoring any limitations on factory turbo) And how much HP at the crank would that produce?

I see most people seem to think 16psi is the max you should run with the T25 turbo. If a 4g63 with a T25 runs 10.5psi stock 210HP @ crank, about how much HP is 16psi giving to the stock 4g63 @ the crank?

The T25 turbo seems to suck. What turbo do most people go to?

I'm looking to get a 97-99 gst/gsx pretty soon

Thanks for the help

 

[paranoidTSi]

Well...your boost is limited by the turbo, plus the fuel pump. the T25 absolutely sucks at HOLDing boost, 17PSI is the max I've heard. Anything higher and you either run into a) fuel cut or b) a turbo that doesn't hold the boost and just leaks.

The max HP support of a T25 is ~280...you won't get beyond that point without upgrading the turbo.

In terms of the turbo most people use, 16Gs seem to be the most common.

 

[Drewcool2]

Cool, thanks.

 

[Defiant]

Originally posted by Drewcool2
The T25 turbo seems to suck.

Actually, it blows. But I'm not the one to split hairs. What it sucks at is use on a 2-liter motor at revs over 5K. For driving MOST of your time, between 1500 and 4500, it does very well. It spools quickly and develops what boost it does early-on. However, it does get breathy and become more an air heater than supercharger at higher RPMs, making it undesirable for use as a drag turbo.

Much in the way it's undesirable to make a dragster out of a 3300-pound street car.

 

[GSntncT]

Most people I've talked to have said 25 psi on stock internals. but now that I see fuel on here too, I'd wouldn't dare raise boost until I've done so. The T-25 does indeed suck. Slot of people dumped th 25 for a Big16G/EVO 16G, to later either go full garrett, or 50 trim-series hybrid.