Still Expierenceing Boost Creep .63 To .82

[Mick_o]

Not ALL split dumps are the badguys everyone is making them out to be. Obviously their design is the big factor. I ran a split dump on my GTX3071R setup and never had a boost contol issue with a 1 bar actuator running 25psi of boost.

[R31 POWER]

^ Exactly. Teh genuine HKS split dump has a notch in it to allow no interference. It also has the gasket that completely separates exhaust/wastegate (for hks gt series turbos)


Then the china copy lots of people have dramas with with the divider for stock turbo, yuck.

Edited May 23, 2015 by R31 POWER

[discopotato03]

I'm hoping this doesn't turn into dump pipe wars , I just think that for the effort and expense involved making divided ones isn't worth it .

The flange plate absolutely has to match the housings inside profile meaning that if the dump side doesn't , function wasn't its primary objective - cost cutting was . Its obviously more time consuming to profile cut the inside of the plate than it is to run a hole saw through it .

I reckon 3.5" tube welded to a properly made GT30IW flange plate with a decent gusset isn't going to lack flow potential on a typical RB25 install . Plenty of exhausts are 3" and they can support good power if the whole system is made with good mufflers cats etc .

A .

[jay-rod]

Yeh dont bother with split.
Wats a couple of cartons to find out if its the dump thats the issue.

Just swap it and see what happens, if it doesnt fix it, one less thing u have to think bout..

[AngryRB]

I been there and done this long time ago, I paid $500 to have the IW modified and an XR6 flapper installed, still no change, then it was decided that the holes didn't line up and the flapper was hitting the flange and all sorts of backpressure... got an open mouth dump and all sorted...

Just get an external and don't stuff around with it, its a waste of time and money...

[Kinks]

I'm hoping this doesn't turn into dump pipe wars , I just think that for the effort and expense involved making divided ones isn't worth it .

If you put the effort and expense in, and you match everything up properly, it is worth it. If you buy some ling long piece of crap for $200 and expect it to work just because it's split then you only have yourself to blame.

It's easy to f**k up a split dump, but it's hard to f**k up a bellmouth. Keep the law of averages on your side unless you have the time and expertise to make sure a split dump fits properly. I'm a huge bellmouth fan because I hear stories of obstructed wastegate travel ALL THE TIME.

[MJTru]

I remember i had an issue like this long time ago with a halset turbo. It just kept over boosting even when i tied the gate open. Talk about lost. So one day i took the turbo off and noticed it was a t3 twin scroll. The gate only vented from one side. The othere side just kept boosting. So over boost hard. I noticed it only controlled boost over 22psi. So thats what i aimed for. I upgraded everything to handle more than 22 psi. She was good after that. Hope thats not your issue mate. Cheers

Edited May 24, 2015 by MJTru

[Dose Pipe Sutututu]

just go external gate and never look back (just under when flames shoot out)

[Jaydenk92]

UPDATE UPDATE UPDATE.!!!!!!!!!!!!!

So as i think i mention the travel of the flapper was stuff all yes. I manage to get a 10mm dump spacer. Which i had to port anyway because it had way to much meat on it, So I ported until it match perfect with gaskets and housing. Slapped it together and i can now flog 3rd and 4th and the boost not only does not move, it drops off at the top (only a little).

So the flapper was fouling on the dump, spaced it out so it doesnt hit and works like a charm. I must also add there is no divider in the spacer so gases can kinda swap and choose its outlet path (thought it would be a issue) but works fine,

Thanks for the dump pipe hit

As for going external wastegate. Yes Highly recommend, but it is a bit tight on a low mount setup (yes i know its been done before). If you can do the whole high mount, FFP ect. ect. go for it as many manifolds are made for high mount to suit external gate. All about budget a commitment

Edited May 30, 2015 by Jaydenk92