Huge Boost Creep

[SXR]

I could be wrong here but I believe dropping the exhaust won't help..if anything I believe the exhaust would need the restriction to slow the exhaust wheel down.

To make boost with no wastegate attached seems to be more manifold issue.

Anyway, we'll drop the exhaust and see how it goes.

[VB-]

bingo, how is dropping the exhaust gonna help? its an atmo gate? if anything a restrictive exhaust will cause boost to drop off wouldnt it?

Edited April 19, 2008 by VB-

[R34NRG]

I dare say that the 6boost item is a tried and proven design, you are not the first to use it and many people before you have had no issues.

It seems you unfortunately don't want to listen to any advise given to try and help your cause.

im with you on the 6boost thing. i dont really think its the manifold either.

all i said is i wasnt sure about the exhaust....as in i dont know if it is....because we were testing the gate issue at the time...

never said i wouldnt do it....

if the gas isnt being bypassed through the gate due to a flow blockage after teh gate - then this can cause the boost to creep - hence the suggestion to remove the exhaust

what boost controller you using? how many vacuum lines to the gate?

the gate is atmo, its not connected back into the exhaust.

the gates been removed which means it shouldnt make any boost.

but it is, which means theres pressure being made by the manifold. because it cant be anything after the gate....cuz there is nothing....

which means theres something wrong with the manifold......

of course this is only theoretical....and it makes sense

rather then taking off the exhaust....and seeing wat happens

Edited April 19, 2008 by R34NRG

[paulr33]

on your dyno plot get ray to plot manifold pressure if you can

youll probably see its ramping off its ass if the exhaust is very restrictive

does the power / torque plummet after aroudn 4 grand?

[R34NRG]

on your dyno plot get ray to plot manifold pressure if you can

youll probably see its ramping off its ass if the exhaust is very restrictive

does the power / torque plummet after aroudn 4 grand?

but i dont see how the exhaust even matters if the gate is fully open.....all the air should be passing through the gate and not the exhaust?

i can only assume power/torque keeps going cuz ray said he had to back off because boost was reaching points of 20psi+ when we turned the boost control off and using the gate spring of .9bar

but ill have to ask and make sure

Edited April 19, 2008 by R34NRG

[paulr33]

no the wastegate is purely designed to reduce backpressure in the exhaust manfiold

its not meant to make all the gas flow through it, otherwise the exhaust wheel would slow down and loose speed, thus loosing boost pressure

so when the gate opens, the exhaust wheel should stop increasing speed (ie: boost should stop climbing and stay even) and all things run happily

if the exhaust wheel keeeps increasing in speed, boost climbs, so its possible the exhaust manifold has tons of pressure built up and stuck inside it

which drives the exhaust wheel faster and faster, much like ":unlimited boost:".

why did you choose 44mm

[VB-]

backpressure because of a crap exaust causes boost to drop off though doesnt it? not creep. 44mm gate was what i told him to get, and i cant see how it would be too small.

im still having trouble figuring out how a restrictive exhaust would cause a turbo to spool with a 44mm gate held completely open?

[R34NRG]

no the wastegate is purely designed to reduce backpressure in the exhaust manfiold

its not meant to make all the gas flow through it, otherwise the exhaust wheel would slow down and loose speed, thus loosing boost pressure

so when the gate opens, the exhaust wheel should stop increasing speed (ie: boost should stop climbing and stay even) and all things run happily

if the exhaust wheel keeeps increasing in speed, boost climbs, so its possible the exhaust manifold has tons of pressure built up and stuck inside it

which drives the exhaust wheel faster and faster, much like ":unlimited boost:".

why did you choose 44mm

that all makes sense but wat im trying to say is that when the gate does fully open....its still not expelling enough gas in the manifold, which keeps the turbine spinning. which causes boost creep

this means a few things

manifold isnt gettn gas to the gate

or

gate isnt lettn enough gas out

i dont know why everyones talking about the exhaust...because the cars creeping even wen the gate is fully open WHICH is suppose to let all the gas through the gate and not the bloody exhaust. so taking off the exhaust wont do jack.

i got the 44mm cuz everyone said it was big enough. tuners, shops, forum members, everyone. even other ppl using similar setups are using 44mms.

are u saying its to small?

Edited April 19, 2008 by R34NRG

[R31Nismoid]

I could be wrong here but I believe dropping the exhaust won't help..if anything I believe the exhaust would need the restriction to slow the exhaust wheel down.

To make boost with no wastegate attached seems to be more manifold issue.

Anyway, we'll drop the exhaust and see how it goes.

A proper 350rwkw/GT35 set-up needs at least 3.5" without gate ATMO especially if your running a 3ltr, cams etc...

A restriction wont slow the exhaust wheel to the point of stopping boost production at full throttle, the turbo will still be making boost from the front end as the exhaust has already been produced & feeding the rear end.

Residual is sitting around causing pressure build up as the motor is making more and more exhaust so its gotta go somewhere and that air is moving faster and faster to attempt to get out.

That's a possibility for what's occurring here and that's my understanding of how it works in a non-educated way

If you think the gate is too small - easy to tell that too. Take the thing off and see what happens, another 5-10mins task

[R34NRG]

A proper 350rwkw/GT35 set-up needs at least 3.5" without gate ATMO especially if your running a 3ltr, cams etc...

theres plenty of 350+ cars out there running 3" all the way with no problems. although i do understand the bigger the better. i think 3.5 to 3" is more then enough on this application. and like i said before it shouldnt be related to anything about the exhaust because when the gate is FULLY open its still creeping

A proper 350rwkw/GT35 set-up needs at least 3.5" without gate ATMO especially if your running a 3ltr, cams etc...

A restriction wont slow the exhaust wheel to the point of stopping boost production at full throttle

no shit.......thats wat im saying, there IS a RESTRICTION somewhere which is causing the exhaust wheel to spin moreeeeeeeee and moree and moreee....not just a lil

If you think the gate is too small - easy to tell that too. Take the thing off and see what happens, another 5-10mins task

found the issue.

droped the gate off and its still causing creep.

the manifold isnt flowing enough air to the gate so thats why its creeping.

very hard to believe being a 6boost manifold.....

only solution atm is possibly redesigning the manifold.

read much ash?

Edited April 19, 2008 by R34NRG

[VB-]

are you serious nismoid? the car was run with no gate and it still made boost, do you even read the posts or what?

Edited April 19, 2008 by VB-

[VB-]

damnnn beaten to it

and in case you missed it, the car has an, ATMOSPHERICALLY VENTING GATE, now how will a restrictive exhaust cause real bad boost creep?

Edited April 19, 2008 by VB-

[R34NRG]

damnnn beaten to it

im gonna be a man here and ask everyone to keep on topic. as much as i would love to take the piss out of ash like he always does to me. ill take a raincheck....

so just to make it clear to everyone.

the car is still causing creep even with the gate off the manifold. stop talking about exhausts cuz its not related.

it has to be the manifold.

but hang on, its 6boost so it cant possibly be it right? i mean its impossible to imagine maybe there might be something wrong with it because a human made it....right

Edited April 19, 2008 by R34NRG

[VB-]

removed - double post

Edited April 19, 2008 by VB-

[SXR]

If you think the gate is too small - easy to tell that too. Take the thing off and see what happens, another 5-10mins task

Yeah did that, about 4000rpm its making 5psi of boost and still climbing.

its strange cuz Mavrics is using the same manifold design and same gate. Had no problem with his. maybe its just a 3 ltr banga motor

Oh well first thing on monday we'll drop the exahust and see how it goes.

I think we need another or larger port from the collector.

We'll keep you updated

[Adriano]

IS it a built motor with headwork and cams? My guess at this stage, is:

A .86 ex housing is a little small for an rb30det, and if it has cams etc, that would make it worse

A 44mm gate is a little on the small side if you are trying to run low boost.

Ivve seen this same problem on Todd Wilkes 1400hp Gicottolo, boost was going off the dial with the wastegate valves installed backwards it had twin gt35r .86's(if i remember correctly) twin 50mm wastegates on a built 5.8. The night between qualifying and comp at summernats we pulled the turbos off and machined the ex housings 1.5mm(and wired in an autronic) Fixed the boost control.

[VB-]

what is the diameter of the port anyway? maybe add another port to the side a bit and blend it in before the gate if theres enough room?

[R31Nismoid]

VB-, if your just going to be a parrot, go to the wasteland.

To date you've offered nothing useful to this thread other that repeating everyone else in the thread because you don't know anything on the subject.

I've said my bit, you don't want to do a 5min check, no problem

Andru, you'll never take the piss outta me when you make yourself look like a silly ass with each post you make here

[paulr33]

ah well

fix it yourself eh

we've tried

[R31Nismoid]

Yeah did that, about 4000rpm its making 5psi of boost and still climbing.

its strange cuz Mavrics is using the same manifold design and same gate. Had no problem with his. maybe its just a 3 ltr banga motor

Oh well first thing on monday we'll drop the exahust and see how it goes.

I think we need another or larger port from the collector.

We'll keep you updated

What turbo is Matt using Ray? Is he 3ltr or 2.5?

I cant remember his setup at the moment as he's changed it more often than i used too

If its the same manifold design and its working on near-similar setup i'm surprised as i know Matt's is going a treat

No doubt the motor is tip top... just don't tell the Mav someone got a better one lol