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Wastegate Flapper Issues, Maybe

4rdr33

By 4rdr33,
in Forced Induction Performance

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4rdr33 Explorer

4rdr33

Posted
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Hi there,

I have an r33 4 door that i got about 2 months ago off a friend of mine, I have been having an ongoing issue with bad boost creeping and spiking. I have a standard turbo running front mount and split dump pipe ( apparently bought off a guy on this sight that makes them), and a pod. now as soon as i go full throttle, the boost just keeps going past the actuator setting anywhere from 10 to 14. I am not running a boost controller. I have put a piece on the hot pipe to run line to actuator, and also replaced actuator aswell. Nothing changed. still over boosting. I detached the actuator arm today and wired the flap open as far as it could go and went for a test drive. Still the car boosted up by about 3000 - 3500 and kept rising to about 9 psi, maybe even 10.

With it open, shouldnt i only get maybe a couple psi by redline, not 9 or 10. I am thinking the split dump has something to do with this, I have checked for boost leaks everywhere i can, and replaced some hoses. I am leaning towards going back to bellmouth dump, i have been told they a a lot more stable on boost and keep the split for when or if i decide to do ecu and tune.

Anyone that has been through this, knows anything about this sort of thing, please shed some light and let me know if i am maybe on the right track.

Thanks to everyone for there help.

Josh

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noddle Rising Star

noddle

Posted
Posted
Hi there,

I have an r33 4 door that i got about 2 months ago off a friend of mine, I have been having an ongoing issue with bad boost creeping and spiking. I have a standard turbo running front mount and split dump pipe ( apparently bought off a guy on this sight that makes them), and a pod. now as soon as i go full throttle, the boost just keeps going past the actuator setting anywhere from 10 to 14. I am not running a boost controller. I have put a piece on the hot pipe to run line to actuator, and also replaced actuator aswell. Nothing changed. still over boosting. I detached the actuator arm today and wired the flap open as far as it could go and went for a test drive. Still the car boosted up by about 3000 - 3500 and kept rising to about 9 psi, maybe even 10.

With it open, shouldnt i only get maybe a couple psi by redline, not 9 or 10. I am thinking the split dump has something to do with this, I have checked for boost leaks everywhere i can, and replaced some hoses. I am leaning towards going back to bellmouth dump, i have been told they a a lot more stable on boost and keep the split for when or if i decide to do ecu and tune.

Anyone that has been through this, knows anything about this sort of thing, please shed some light and let me know if i am maybe on the right track.

Thanks to everyone for there help.

Josh

I have the same issue with my turbo, the internal flapper hole is to small.

I opened it up by a few mm but the problem is still there,

I'll be fitting a external gate.

Nigel

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KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

I had no problem with my off the shelf split dump but if yours is catching the wastegate surely a few minutes work with an angle grinder should "adjust" it to fit rather than buying a whole new front pipe.

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4rdr33 Explorer

4rdr33

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Thanks for the replies so far, seems people have mixed views on this subject. I have also been told that split dumps flow so much freely and that can cause wastegate creep also, something to do with pressure. Not sure myself. Any ideas if I will lose much power by going back to a bellmouth.

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ClutchBurndout-:( Grand Master

ClutchBurndout-:(

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i dont know if this could cause it, but jjr split dump pipes are pretty poor quality (if its a jjr one, but this being said, maybe a lot of them are like this), im not saying this because i hate jjr or anything but from hands on experience, when i bought one before my bellmouth, i inspected it and noticed that the hole for the wastegate pipe that joins to the main pipe is poorly cut, and in actual fact is only about 50%-75% size of the actual wastegate pipe, so say that the wastegate pipe part of the split dump pipe is the site of a 50c coin, the opening on the main pipe is only the size of a 10c coin... i fixed this by spending about an hour filing away at the hole, but all this being said i dont think i had any issues with boost creep that wasn't boost controller related, i used to get boost creep right up to 14psi (when the boost controller was set to 12psi) i fixed this by getting a evc, but a turbotech boost controller is just as good.

hope some of the this info sheds some light

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Kinks Grand Master

Kinks

Posted
Posted

split dump for sure if your problem. put a bellmouth on.

why f**k around trying to get a split dump working (grinding bits and pieces) when the split dump gives you no performance advantage? 2 small pipes has much less surface area than a bellmouth that covers the whole turbo exhaust flange, and tapers down to 3" nicely. plus, with the dump you are using the full exhaust when you are off boost = better efficiency. with the split you are only using the main pipe.

put a bellmouth dump on. I've heard so many stories of JJR split dumps fouling the wastegate, boost creep etc. However their stainless bellmouth dump is actually quite nice quality. flanges are good, TIG welding is very neat and the finish on the pipe is fine. I was really pleasantly surprised when i received mine. there is no "maybe it will work maybe it won't" as with a split dump and whether the actuator fouls. then you get your split dump working, get a high flow they fit a bigger flapper on the gate and then it fouls again!!! screw that for a laugh.

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4rdr33 Explorer

4rdr33

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Well I went with the choice of going back to a bellmouth. Not the best solution but for now it will do. If it solves my problem which I'm pretty confident it will. There is nothing else left for me to check, I will keep the split dump for when I change turbo's and do ecu upgrade.

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NSNPWR Rising Star

NSNPWR

Posted
Posted (edited)

You running a cat converter or got a decat pipe in there?

You can check to see if the gate is catching on the dump...unhook the actuator and check its range of motion...they will never open 90 degrees, if it opens to half of that its working fine and has sufficient clearance.

Edited by NSNPWR
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