b18cx

I know this subject has been beat to death, but my question is a little different. Let me start out by stating this, I do not want to cork up the exhaust. I have tried everything I can think of to solve this.

Please do not respond by saying get a new manifold or just flaming it , please, unless you can tell me WHY. Not trying to be an ***, i just want to understand

the basics: JDM GSR, Perscion SC61, OBX/Ming/Spark racing manifold (rewelded/braced), 3" downpipe to straight 3" exhaust, Tial 35mm wastegate with .45 bar spring, Hondata S200, Dyno tuned for creep to 9psi. Did 320 whp.

The problem: Boost creep. Spools up great. gets to .45 bar(6.5 psi) and stops, then starts creeping as rpm goes up. Creeps to about 8 1/2- 9psi.

What we have tried: New vacume line, new vacume source, porting wastegate outlet on mani., replaced wastegate outlet on mani., went from 1 3/8 I.D. to 1 7/8 I.D., and have had no luck. the people I have talked to all say get a new mani. WHY?

I am thinking about getting a Lovefab from Tinker, but I would like to know why the LoveFab or the Full Race are going to solve my problem.

Any help or real suggestions would be appreciated!

Hear is a pic of the original wastegate outlet



The set up


And the new wastegate outlet. And notice we angled it down slightly

S2KP

Switch over to a bigger wastegate?

gritsak

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Turbo_Siii &raquo;</TD></TR><TR><TD CLASS="quote">Switch over to a bigger wastegate?</TD></TR></TABLE>

nooo its not the size of the wastegate thats the problem...plenty of people have tooken tial 35mm's much further then that.

before i saw your second pics i was thinking, damn the wastegate elbow is angled up like a bitch and must not be letting enough exhaust gasses out, but you must have already noticed that and when you get it rewelded put it at a better angle...

i looked at it for a couple minutes and the only thing i can come up with is that because the design of the manifold uses those crappy colletors that you ust weld the runners in...and from the placement of the wastegate it looks like its really only venting two of the runners, but then again ive seen other manifolds (like revhard tubular) that have the wastegate off only one runner period and they seem to do alright so i dont know if that could be the problem either.

have you tried switching out to a different 35mm and see if that does anything? i mean a wastgate is a pretty simple thing and i would assume it would be hard for it to mess up but its gotta be possible.

b18cx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gritsak &raquo;</TD></TR><TR><TD CLASS="quote">

nooo its not the size of the wastegate thats the problem...plenty of people have tooken tial 35mm's much further then that.

before i saw your second pics i was thinking, damn the wastegate elbow is angled up like a bitch and must not be letting enough exhaust gasses out, but you must have already noticed that and when you get it rewelded put it at a better angle...

i looked at it for a couple minutes and the only thing i can come up with is that because the design of the manifold uses those crappy colletors that you ust weld the runners in...and from the placement of the wastegate it looks like its really only venting two of the runners, but then again ive seen other manifolds (like revhard tubular) that have the wastegate off only one runner period and they seem to do alright so i dont know if that could be the problem either.

have you tried switching out to a different 35mm and see if that does anything? i mean a wastgate is a pretty simple thing and i would assume it would be hard for it to mess up but its gotta be possible.</TD></TR></TABLE>

I was using this wastegate on another car and worked like a champ. Then again, I was also using a Drag mani.

b18cx

am bump

st00pid

Exhaust pulses are travelling near the speed of sound, why would it want to make a 120 degree turn when it has a nice path to follow straight to the turbo? You really shouldnt think of the exhaust as pressure in the manifold, its is not sitting still waiting for a hole to push out of. Instead think of it as a fluid, like water, if you were shoot water through that manifold at the speed of sound do you think ANY of it would want to flow through the wastegate port on the first pic?

By having the WG port angled like that you could actually suck air into the manifold. scavenge systems use exhaust flow to pull air out of the crankcase by putting a tube at a 120 degree angle with the exhaust flow.

Bailhatch

you didn't get any improvement at all with the new placement?

It seems much better. Idealy the path to the WG and turbo should be of equaly resistance to the flow but as it was stated above really bad designs seem to work pretty ofter.

You just need one wastegate for each runner..thats all

b18cx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by st00pid &raquo;</TD></TR><TR><TD CLASS="quote">Exhaust pulses are travelling near the speed of sound, why would it want to make a 120 degree turn when it has a nice path to follow straight to the turbo? You really shouldnt think of the exhaust as pressure in the manifold, its is not sitting still waiting for a hole to push out of. Instead think of it as a fluid, like water, if you were shoot water through that manifold at the speed of sound do you think ANY of it would want to flow through the wastegate port on the first pic?

By having the WG port angled like that you could actually suck air into the manifold. scavenge systems use exhaust flow to pull air out of the crankcase by putting a tube at a 120 degree angle with the exhaust flow.

</TD></TR></TABLE>

OK?? I thought I kinda covered that. If you notice in the last three pics, When we made a new wastegate outlet, we not only made it bigger, we angled it down a little ( refer to last pic) to now go with the flow of exhaust gases. No difference. I noticed the Lovefab's and the full race mani's come straight out, no angle. Am I missing something here?????

Or, are you trying to say I might need to extend the wastegate outlet into the collector with the end cut at 120 degree angle to help "catch the flow"???

raene

He's saying that having a tube positioned at 120 degrees next to a high-velocity column of gas like that actually acts to create a low-pressure zone in the wastegate tube itself. Like he said, old-skool domestic guys used a tube in their exhaust to create a low-pressure zone for PCV operation without plumbing it back to their intake manifold because of the low-pressure-zone-creation effect.

b18cx

I understand what you guys are saying, But are you looking at the last 3 pics? The wastegate outlet is pionted into the stream of flow. Not pointed with the stream of flow like the FIRST pic.

Maybe I'm just not understanding it. If having the wastegate outlet at a 45 degree angle it would creat a vacume as pictured in the first pic (I understand that , thats why I changed it), then would changing it to 120-150 degree angle, with the tube pionted into the flow, Like pic 3, would it not want to catch the flow and divert it out the waste gate???

Im thinking of it like this. Turn the water faucet on. Water flows down to the drain. You take a straw and insert it at a 45 degree angle(1st pic) . Nothing . now insert it at a 120 degree angle(3rd pic)(pionted into the flow) water flows out the end of the straw. now inset it at a 90 degree angle Love Fab/ FullRace), Some flow but not much. thats how I'm thinking of all this. Am I rihgt??? Maybe I neeed more angle??
How does the loveFab/ Full Race mani's work with the outlet positioned at a flat 90 degree angle. Maybe I need a turbo that doesnt spin so freely? Maybe I am over thinking this and my brain is fried.

Turbocivic94

I'm having the same problem as b18cx. I switched to 2 different wg and nothing is helping. Is it have to do with poor quality manifold.

0project dc2

iTrader: (1)

=T thats a stone mountain racing manifold, at least OBX/Sparks/MEng has a real collector. this is just a .. hrmmm how do i say it .. CHEAPER imitation of the cheap manifolds. haha

Turbocivic94

So what can we do to fix the problem rather than buying another manifold or bigger wategate. I got 35mm HP wategate and t3/t4 Stage V with 1.00 A/R housing.

gritsak

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 25 PSI CRX &raquo;</TD></TR><TR><TD CLASS="quote">So what can we do to fix the problem rather than buying another manifold or bigger wategate. I got 35mm HP wategate and t3/t4 Stage V with 1.00 A/R housing. </TD></TR></TABLE>

sweet jesus, why do you have such a big a/r?

Turbocivic94

wanted the stage v wheel and didnt want to spool up quick. around 5200 rpm this turbo is killer

Turbocivic94

check out the pics of my turbo

http://www.we-todd-did-racing....DE%3D

http://www.we-todd-did-racing....DE%3D

http://www.we-todd-did-racing....DE%3D

If some one wants to post them, please feel free to do so. Thanx



Modified by 25 PSI CRX at 3:30 AM 8/8/2003

st00pid

even still you are bleeding energy from one primary, My suggestion is bring another tube from the other side and have the WG control from both sides.

b18cx

pm bump for the pm guys

Turbocivic94

Do I have to go with a bigger wastegate or 35mm HP would do the trick.

hotboi850

Because of the design of that manifold. A bigger wastegate is the only way that will solve ur boost creep problems. There's probably nothing wrong with ur tial wastegate.

If you could somehow make the exhaust gases flow towards the wastegate. Instead of flowing past it. At high rpms, exhaust gases can't just make a u turn and flow toward the wastegate.

hope this makes sense to you.

JrCRXHF

I have this same manifold i have not hooked it up yet but this is what i do not understand is if you look at the drag manifold the wastegate hooks up to just one runner too so why does that not have boost creep problems?

gritsak

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by st00pid &raquo;</TD></TR><TR><TD CLASS="quote">even still you are bleeding energy from one primary, My suggestion is bring another tube from the other side and have the WG control from both sides.</TD></TR></TABLE>

i agree with this...just putting a huge wastegate on there isnt the answer...you need to fix the problem at its source, the manifold/wastegate design.

JDMports22

I have an OBX manifold with the same problem. It holds boost to a certain rpm then it spikes like crazy. I was thinking that maybe having a wastgate opening on the small hole of the exhaust housing tied into the opening on the manifold then to the wastegate. Or maybe an opening on both sides of the manifold tied together in the middle. This should be enough flow to cure the problem

b18cx

I know its not cost efective but what if I addad another wastegate on the opposite side? Any thiughts? And buy the way, How do I get ahold of LoveFab to buy a manifold? Tried PM'ing Tinker, but have had no response

TurboJesse

I will be running the same manifold and want to make sure this won't happen to me when i go to get tuned, So basically the only thing i can do to prevent this is have 2 wastegate outlets (one on each side of collector), angled downwards that merge in the center where the wastegate flange would be. Correct?