Intake brainfart

[Sir Yach-o]

I was thinking too much about my Subie on my lunch break today, and was trying to come up with a way to improve low-end power. I figured that the turbo was too restrictive as the only means of air flow when it's not spooling, so I wondered if there would be a way to bypass it. I could just run a hose from before the turbo to just in front of the throttle body, but that would mean that under pressure when the turbo was spooled, pressurized air would be stuffed down that tube and back the wrong way, reducing the effect of the turbo.
So I decided that some sort of valve would be needed that would close the extra airway under pressure... hmmmm... BOV! Under vacuum it would be open, and under pressure it would close up again!

Any thoughts?

-mike

[vrg3]

Doesn't the stock blowoff already do that?

The BOV's piping is less than an inch in diameter, so it's not clear that it's less of a restriction than the compressor.

[-K-]

I don't think it is worth doing anything, if you look at a boost/vac gauge as soon as I'm on the gas it goes from vac to 0 and then builds boost from there.

[SubbyRS]

Don't think it would do anything worthwhile.....what you REALLY want is adjustable compression run the motor at (say) 10:1 before boost builds & as boost climbs it drops back to 8:1......

[czo79]

I think saab has designed a variable compression engine, weird thing it is. Don't know if it will ever make it to production. I was looking at a toyota 87 supra inline 6 turbo for a friend the other day, and I couldn't figure out its intake at all. It had a rather normal looking turbo and intake with a cone filter and all, but I couldn't see where the turbo actually fed into the intake manifold and throttle body. However, there was another intake looking tube, that (if I remember correctly) went into the fender like ours do, and went (on the other end) right into what looked like the throttle body and intake manifold. It was really weird. I couldn't figure it out. I was thinking just what you were, that it has this long runner intake when off turbo for low end torque and a short straight intake when on turbo for high end power, but I still couldn't figure where the turbo connected to the manifold/throttle. I wonder if it had two throttle bodies two? nah...I'm crazy!
Micum