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Still Expierenceing Boost Creep .63 To .82

Jaydenk92
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Mick_o Grand Master

Mick_o

Posted
Posted

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.

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R31 POWER Mentor

R31 POWER

Posted
Posted (edited)

^ 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)
52715-5_11.jpg

Then the china copy lots of people have dramas with with the divider for stock turbo, yuck.
dump_pipe_rb20_dp_3_44954.jpg

Edited by R31 POWER
discopotato03 Grand Master

discopotato03

Posted
Posted

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 .

AngryRB Grand Master

AngryRB

Posted
Posted

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 Grand Master

Kinks

Posted
Posted

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 Mentor

MJTru

Posted
Posted (edited)

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 by MJTru
Jaydenk92 Apprentice

Jaydenk92

Posted
  • Author
Posted (edited)

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 by Jaydenk92

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