s5 turbo stock wastegate question

[Boostmaniac]

Originally Posted by FerociousP

thanks maniac thats what I wanted to hear... in your experience what's a good one that isn't going to be too much money for what i'll be using it for (getting 4-5 more psi) ?? I understand I can use it for multiple setups but none of those are in the even remote future... thanks again... should I shy away from MBCs??

MBC's are awesome if you are on a ramen budget. They have a negative side effect though, they only control the peak pressure. They restrict the wastegate from fully regulating boost a little late. Think of this as a FCD in a way. They fool the wastegate into thinking 10 psi is the stock psi so it just opens a little later.

BUT

There is a side effect that you won't notice until you ride in a car equipped with an EBC. The wastegate still opens a little bit so the transient boost response is still not as fast as it can be, AND you have to fiddle with it to get it set JUST right, meaning multiple times of getting in the car, boosting, getting out and adjusting under the hood (or in the car if you route some vacuum lines into the cabin), boosting some more etc etc. You need to check the boost in a higher gear to make sure it won't creep under high RPM full load past your preset point.

We used one on an FD once to just see how well it worked and we ran into a small (thank god) oopsie. Someone had completely shut the MBC not knowing what it was when it was off the car. We put it back in and boosted in second gear. This car was tuned for 14 - 16 psi, we recorded a full 26 psi on an instantaneous boost spike since the wastegate would not open. He lifted the throttle as fast as he could and we heard a massive explosion. Turns out the Rubber line connected to the BOV had ruptured while trying to vent this pressure and literally blew the BOV off of the piping. It was hanging down by the turbo by the vacuum line. If you get a MBC, just please be careful, we got lucky and he had a fast foot, otherwise it would have been rebuild time.

As for the EBC, anything commonly found will work great on an FC. I always liked the ones using the fuzzy logic to predict spikes and keep the boost steady. I am sure you can find one used somewhere dirt cheap, just make sure to get the instructions for installation and setting it up. Also, be prepared to do Bar conversions if you get one from overseas.

Here are a few on this page you can look at. The prices are high, but they are worth their weight in gold IMHO. They also have features that a MBC just can't do, and that MIGHT mean the difference between flawless boost response and accidental rebuild time.

http://corksport.com/store/category/5pjf/turbo.html

Take your time to research the pro's and con's of each and then make your choice based on your budget / setup. Since I am mostly worried about low end production and a fat useable powerband, I am ALL about the EBC's, but a MBC will also work if you are short on cash for the time being and just need to put some trash talking friends in your rear view.

-Maniac

EDIT : what you will be using it for would be perfect either way. I would suggest looking around for a used one with a complete harness and instruction manual. If you need a MBC on the super cheap though, I think I still have my schematics for the Home Depot special. Don't laugh, it really does work. That was the one that nabbed us the 26 psi. It costs about 5 bucks. Just remember the old adage, cheap usually costs more.

[TehMonkay]

Yeah look for a nice use one on a local forum.