boost creep with 44mm gate?

[meet07]

My setup

-stock rb25
-stec manifold
-borg warner s366
-44 precision wastegate
-aem series 1

Tuner called yesterday and told me that my car was boosting 17lbs and creeping up past 20psi around 7700rpms. My stec manifold with the divided ports has 2 primaries merging to one collector. Its a nice setup so I don't see how its creeping. Has anyone else had this issue? Can someone shed some light on the scientific side of manifold/wastegate control? Tuner said the turbine housing may be to big and gate to small?

[julio]

I had the same problem with my ebay (similar design to stec) and tial 44mm WG. The WG runners are just too long to provide enough flow to the WG. The low backpressure of the s366 turbine probably doesn't help either.

You can either live with the creep, or get your manifold modified for 2 WG's.

[meet07]

I was considering putting in a lower spring and dealing with it until next year. I mean I already have 1 precision gate. Just purchase another and get the manifold hacked up for the 4th time...bummer

[RRRRB]

alot of its placement and the merge into the wastegate runner, in most cases its never ideal.. and thats just simply because you cant always design it perfectly into the given application

your best bet is either to try and direct flow into the runner with a "tab" at the wastegate runner entry or to add a larger gate.. or add another gate..

My setup crept very bad with twin 38MM MVS.. to the point i couldnt even go full throttle without hitting 25psi in the higher rpms i welded on 44mm MVR's and now it will hold 17psi

[RRRRB]

if its truly a wastegate flow issue, a spring change wont help much if at all, you will just get less boost in the midrange and it will still creep up top

[meet07]

if its truly a wastegate flow issue, a spring change wont help much if at all, you will just get less boost in the midrange and it will still creep up top

What size turbo are u running?

[RRRRB]

I'm running a Precision journal bearing 6766sp with a 1.00 T4 divided housing

[meet07]

You have any pictures of your manifold? And how are u routing the lines from the turbo-boost solenoid-gate? I'm using the .88 AR housing...smaller than 1.00?

Typo*I have the Precision 46mm gate

[RRRRB]

You have any pictures of your manifold? And how are u routing the lines from the turbo-boost solenoid-gate? I'm using the .88 AR housing...smaller than 1.00?

Typo*I have the Precision 46mm gate

I'm running my lines from the compressor housing Tee'd off to both gates and the boost control solenoid, and from there to the top ports.

.88AR open T4 is probably pretty comparable to the 1.00AR divided

Brand new with the 38mm flanges on it


In car with the 38mm gates on


How it is now with the bigger gates and dumptubes.. I still have AC thats why its routed the way it is. Tight.. but it works fine

[meet07]

Will twin 46mm gates be to big for what I'm trying to achieve?? Stock motor no more than 500whp at the moment?? didn't know if twin 38's would get the job done. Looking for the quickest spool possible.

[RRRRB]

Will twin 46mm gates be to big for what I'm trying to achieve?? Stock motor no more than 500whp at the moment?? didn't know if twin 38's would get the job done. Looking for the quickest spool possible.

No such thing as to much wastegate, you already have 1 46mm gate. If you have the room for twin 46mm gates i would go for that, and would for sure take care of the problem.

Gate size has nothing to do with spool.. its all whats controlling them and how you have the controller setup.

you could also do a 60mm gate.. all depends on the room you have..

keep us posted

[meet07]

Might be a dumb questions or down right ghetto but for some reason it works In my mind. Ok I have decided that I will keep the 48mm precision gate and will add another gate. Now the Tial 44mm gate and the 46mm precision gate both bolt up to the same inlet flange. Could I just use a 44mm gate on one side and 46mm precision gate on the other?? Will there be some boost controlling issues with the little 2mm difference??

I can find a second hand 44mm gate for cheaper than I can a 46mm gate?