How much boost?

[CompOrange]

I've got a 97 Spyder GST, how much boost should it be making stock? and how much can I get out of the stock turbo safely?

[Shane@DBPerformance]

It should run around 12psi stock. You have to replace the stock BOV, if you want to turn up the boost. It leaks a lot at higher than stock boost levels. You also want to put on a bigger exhaust system, so that you aren't just creating a lot of backpressure, if you turn up the boost. The stock turbo won't sustain high boost, it can't flow enough air to keep up with the engine at higher RPMs. You can turn it up so that it spikes up to 18psi, but the boost will just fall back down pretty quickly.

[Gravy]

I thought for eficiency reasons, the t-25 should never see above 16, same as the 14(both are on stock air systems) should never see above 18 without heavy cooling mods, and fuel mods. I know the 14b CAN hit 20 psi, but you heat soak after one run of hitting 18's.

[Shane@DBPerformance]

A bigger turbo will heatsoak an intercooler even faster than a small turbo. A small turbo will put out high temps at higher boost, due to a less efficient compressor wheel, but they don't flow a lot of air. 600CFMs of 190 degree air from a bigger turbo with kill and intercooler much quicker than 275CFMs of 230 degree air. The 14B is just big enough to be dangerous. With race gas, you can run the 14B well into the mid 20s and it keeps making more power/torque. The T25 is so small that it can't max much out or hold over 15-16psi once you get into some decent RPMs.

[Gravy]

And this gent is talking about on the stock SMIC. I know people have pushed their 14's into 11 seconds, with HELLISHLY good tuning. But with the stock system, 16 is about the best you can do before heatsoaking. At least this time of the year. Winter you could do better, if you tune for it.

[Shane@DBPerformance]

He has a T25.

[Gravy]

i know, :-P

also, the 2g IC looks smaller then the 1g, and from what i hear, cools less efficient.

[niterydr]

The 2g cores are smaller.
Set your boost for around 14psi, and you'll be fine. (I would add an intake, exhaust, and bov before turning up the boost. Having fuel mods in place is always a great idea).

[Gravy]

The car i'm working on is running 20 psi with no fuel mods, you'll be just fine!!! :rolleyes:

I've heard to be safe no boost above 14. Stock can handle 16, but at a much higher risk of breakign things. The stock can see, and cool for the most part 14psi on both the 1g and 2g all day long.

Follow a "Breathright" upgrade path first, then work your way into fuel system, boost mods, then turbo.

[Eagle_of_Fire]

^^ Right on. If you wanna feel what the stock T-25 has to offer then eliminate restriction.. i did intake, turbo back exuast, hard smic pipes and bov. What a difference those few things can make for that turbo.