High boost on stock longblock

Splinter · Post by **Splinter** » Wed Apr 26, 2006 4:40 am

Im putting in my walbro 255lph pump tomorrow, and I was going to bump the boost up to 16psi and put in vikashs FCD

I'm intercooled (saab 900), and possibly putting in a waterspray (external)

Anyway.

16psi, am I gonna blow out the headgaskets or anything?

555BCTurbo · Post by **555BCTurbo** » Wed Apr 26, 2006 4:45 am

If you are running the VF11 still, that will be waaaaaaaaay outside of the turbo's efficiency range, so I wouldn't take it past 12-13 psi with the stock turbo...it will just blow hot air past that.

Splinter · Post by **Splinter** » Wed Apr 26, 2006 4:46 am

Isnt there quite a few people on the board running 15-16psi on the vf11?

That was my understanding

555BCTurbo · Post by **555BCTurbo** » Wed Apr 26, 2006 4:54 am

You can, but there is really no point, as it will just blow mad hot air

Hot air=no more power

Splinter · Post by **Splinter** » Wed Apr 26, 2006 4:56 am

Damn.

Well Im still gonna put in the FCD since I keep hitting boost cut when it surges sometimes (jumps up to 14psi on gear shifts when MBC is set to 11)

dzx · Post by **dzx** » Wed Apr 26, 2006 5:03 am

When my car was on the dyno we found it didn't make more power past 13psi. It was putting down 180wtq uncorrected though with the stock turbo.

555BCTurbo · Post by **555BCTurbo** » Wed Apr 26, 2006 5:16 am

^ Thanks Dan for backing me up

vrg3 · Post by **vrg3** » Wed Apr 26, 2006 1:43 pm

Don't forget about keeping a decent air/fuel ratio.

Kelly · Post by **Kelly** » Fri Apr 28, 2006 7:16 am

My car put down 220whp somewhere around 18psi on the VF11.

I dont know why, or how, but it did.

Stock maps, 92 octane.

Maybe thats why it smokes so much now.

Splinter · Post by **Splinter** » Fri Apr 28, 2006 7:46 am

Any sign of those base maps for the smc yet?

Matt Monson · Post by **Matt Monson** » Fri Apr 28, 2006 4:23 pm

Based on the modelling I did a few years ago with the boost maps and pressure ratios, etc. etc. I came to the conclusion that you SHOULD still see gains up to 15psi on the stock turbo. Since I sold my car before I ever got to test it, I don't have any real life tuning to back it up, so make your own judgements.

Also, choice of IC will impact things. That Saab IC is pretty small, and you may exceed the efficiency of the IC at a boost level that is lower than where the turbo itself starts to loose efficiency. Realistically, the only way to figure out where your set up runs best is get it on the dyno and take a handful of pulls at different boost levels...

my3awds · Post by **my3awds** » Sat Apr 29, 2006 12:33 am

Isn't there too many factors to guesstimate how much psi you should use just based on your mods (ie octane level, air temps, elevation, etc)? I would go with a somewhat more accurate way then what 'most people use'...such as a Wideband, EGT, and O2V gauge. That way you don't go damaging the motor, and you get a closer idea of where you should be. It's too bad they don't have free logging software for the obd1 subies like they do for the dsms

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High boost on stock longblock

High boost on stock longblock