Craze8

I know this subject is covered often. I have a free flowing intake and a racing beat turbo back exhaust with both mufflers in the rear. I have ported the gate opening out to about 32mm and the creep is still present in 3rd. Creeps to 13psi on nothing but the factor gate. Other then modifying creating a seperate outlet for the gate and tying it back into the exhaust any other possible ideas?

jesseluck

iTrader: (2)

When I ported mine I also removed from the sides to enlarge the hole. About the size of a Honda exhaust valve. No creep.

Craze8

I used a 1.8t exhaust valve which was larger then most of the honda valves ive come across. Thats why I am still scratching my head as to why it still creeps. Made sure it had plenty of clearance around the outside of the valve as well.

eage8

iTrader: (9)

you can grind the back wall of the plate so the valve can open more.

something like this:


I have a super rare KSP down pipe that has a divorced pipe for the wastegate gases:





I have a separate one that's not as nice for sale... but it won't fit an S4 turbo.

eage8

iTrader: (9)

Here is a picture of how large BNR ports the S4 gates:

Craze8

I didn't quite go as far as the BNR port, didn't think I would need that much on the stock compressor still, though I guess I was wrong... I did work with the backing plate, but didn't take much out of it. Guess I can cut at that next. I have a spare plate I can experiment with.

Was thinking of working at creating something along the lines of a diverged/bellmouth setup similar to what the WRX/STI guys purchase as I readily see them in my line of work with working on Subarus and VWs. Was going to cut the backing plate and weld a pipe onto it and tie it back into the exhaust stream.

I will play with the backing plate first. Thanks for the input eage8. Trying to get this thing situated so I can make some track passes on roadcoarses and Autocross later this year.

2-N-D-pink

iTrader: (27)

You need back pressure. Otherwise youll over boost.

On my set up, I would still over boost. And that was free flow intake (no afm with lt10s) and 3 " exhaust to 2.5" duals. The waste gate was completely removed with the flappler and an external tial38mm in place. Still over boosted until I added some metal slits on the down pipe to add back pressure. Not so much free exhaist flow helped even tho its a "hack" I have a .9 bar spring and id stick 13 psi from 3k to 6k rpm. Then after 6k rpm boost pressure dropped to 6 psi.