Boosting Problems After Installing Dump Pipe

[Birds]

Thanks mate, I'll give him a call if I can't sort this crap out.

[mad082]

i had a dump pipe like that on my 33, however before i put it on i had to fix up a few issues with it. i made sure that the divider was as far down as it would go so it wouldn't foul on the wastegate flap. to do this loosen the 2 bolts about a turn, push the divider towards the bigger hole then tighten the 2 bolts back up. the second thing i did was grind out where the wastegate pipe joined back into the main pipe. on mine it had been welded majorly crooked so there was an overhang of about 1cm x 2cm of pipe that would've restricted flow of the wastegate gases. this may be a similar issue to what you are having. if the wastegate flap is moving properly but you are still having issues with higher boost then it may be that you have a similar issue and the wastegate gases are being restricted, forcing them to go through the exhaust wheel, creating higher pressure.

as for the issue of it not boosting in 3rd gear, that is a prime example of a wastegate not closing. this can be caused by 2 things. 1 is the dump pipe fouling the wastegate flap, the other is a dodgy boost controller. i had this exact issue when i had a turbosmart boost controller on my car. i would boost it up, change gears and even at 4000rpm in the next gear i would have zero pressure. if i lifted off again and stayed off the throttle for a few second then accelerated again it would boost up fine. pulled the controller off and put my old turbotech one on and never had the problem again.

[R31 POWER]

I cut the small wastegate pipe off and put a 2inch screamer pipe on. Boost never creeped after that

[Birds]

i had a dump pipe like that on my 33, however before i put it on i had to fix up a few issues with it. i made sure that the divider was as far down as it would go so it wouldn't foul on the wastegate flap. to do this loosen the 2 bolts about a turn, push the divider towards the bigger hole then tighten the 2 bolts back up. the second thing i did was grind out where the wastegate pipe joined back into the main pipe. on mine it had been welded majorly crooked so there was an overhang of about 1cm x 2cm of pipe that would've restricted flow of the wastegate gases. this may be a similar issue to what you are having. if the wastegate flap is moving properly but you are still having issues with higher boost then it may be that you have a similar issue and the wastegate gases are being restricted, forcing them to go through the exhaust wheel, creating higher pressure.

as for the issue of it not boosting in 3rd gear, that is a prime example of a wastegate not closing. this can be caused by 2 things. 1 is the dump pipe fouling the wastegate flap, the other is a dodgy boost controller. i had this exact issue when i had a turbosmart boost controller on my car. i would boost it up, change gears and even at 4000rpm in the next gear i would have zero pressure. if i lifted off again and stayed off the throttle for a few second then accelerated again it would boost up fine. pulled the controller off and put my old turbotech one on and never had the problem again.

That's good estimation lol. I just put mine straight on...the number of times I've taken it off is ridiculous, I'm now pro at removing the damn thing. It was doing the no boost thing in 3rd gear when I had that divider in place and it was jamming the thing open...after I removed it, I always had boost no problems...just too much of it! Which I attribute to the flap not having a full 90 degrees worth of opening. Turbotech boost controllers are fantastic for their price...I have one but it's not installed on the car.

Gonna give a JJR exhaust system a go instead.

[Beer Baron]

The assumption is that exhaust piping is a pretty safe bet, with the worst that can happen being wastegate issues or a shitty sound. Besides, the front pipe is/sounds fantastic and together with the dump pipe it cost half that of a Jap powerhouse branded front pipe...so I will have no regrets even if I resort back to the standard dump.

it was a poor assumption. the cheap dumps are cheap and they are crap. the jap dumps costs twice as much because they are twice as good. they actually test and use the dumps they make. the people in china copying them have probably never even seen a skyline let alone tested they dumps on them. plus their QC is not always up to scratch meaning you could by 5 dumps from the same factory and find they are all a little different/warped. you pay peanuts... you get monkeys.

[Birds]

Oh well, I'd bought a de-cat pipe for $80 from China previously and that bolted straight up no hassles so I figured "how bad could it be" getting more piping from the land of one child.

[dyefuker]

funny, after reading this whole topic, i actaully did/have the same problem,

bought a cheap split dump of ebay, was umm 110 i think, and yeh installed it and the boost just keeps climbing,

so not nothing more than a quarter throttle it is for now lol, and i know the gate is hitting something as it wont open anymore than maby 5 degrees,

gota pull the dump off again and do exactly what i have just read, grind some more space for it,

had no problems what so ever with the stock dump/front pipes, changed them and now no boost controll,

though i did notice a fair bit of power gain and responsiveness off boost, and the little bit of boost iv experianced,

and also i have noticed a kind of whineing noise the turbo makes now down the exhaust pipe as it spools