I was reading BV1's thread on the E-RAM, and a thought occurred to me:
The power brakes on any modern car use engine vacuum from the intake to provide assist to the driver when he/she applies the brakes.
An engine with a turbo, a S/C or anything of the sort, including the E-Ram, would have no vacuum in the intake, as air is always being forced into the cylinders, rather than having the cylinders pull the air in, as is the case on a naturally aspirated engine. Therefore, a car with a stock turbo, like a Mitsu Eclipse, (or a diesel engine, cos diesels don't produce any vacuum either) would have a different power assist system for the brakes, like a vacuum pump.(This is what I can remember from years of reading about how cars work)
So my question is this: If you install an aftermarket turbo on an engine that was designed as a naturally aspirated engine, what happens to your power brakes?
Are these turbos somehow designed to allow some vacuum when the throttle is closed so that some vacuum is available for the brake system?

 

When Going FI you don't often (often being the key word) break and give it the gas at the same time.

When you go to stop the butterfly in the TB should be closed as you are not giving it gas.
The engine then makes vacuum again to help breaking. Just like before going turbo.

But yes if you are going full bore and slam the breaks while hitting the gas. The breaks will not work nearly as well.
Hope that helps

 

He's got it right smile.gif

Also as a final note, if you're really concerned about your braking ability WHILE under boost (for god-knows whatever reason wink ) then you can just run an inline vacuum canister.

The idea is a small steel "bottle" with a one-way checkvalve to attach it to the intake manifold and then a normal line to the brake master cylinder. You build up vacuum inside this little bottle when the car isn't boosting, but the one-way checkvalve keeps the vacuum IN the tank while you're on-boost. The normal line to the brakes means they always have vacuum, no matter what your intake manifold may be seeing.

Costs about $50-$80 for the parts and would probably take half an hour (at most) to install.

 

Random recently posted that he would be doing this for his car. He noted that durring "emergency" braking such as on the highway he was having issues stopping.

 

If while accelerating...someone cuts me off, and I have to get on the brakes...when I go from boost to brakes very fast, the brake pedal is has hard as a rock, and it doesn't do much.

Then the vacuum kicks in, and the brake pedal get's soft, and the brakes kick in HARD!!!

I just installed a 1 way check valve. That did the trick. The Master cyclinder retains it's vacuum, and I get to have "normal" brakes!

 

Thanks for clearing that up for me, guys...



Nice to know there's someplace I can get answers to my questions!

 

Random that sounds like a beautiful setup, do you think SR will ever decide to sell those?

 

The turbo kit is alpine's. The 1 way valve is actually a PVC valve from Fram! *evil grin*