Sick of boost creep - what to do?

[TR Custom Parts]

Starting to miss my old TA49 setup........ 6262 ball bearing billet turbo, running one of the downpipes I sell with a 38mm external gate. This setup worked fine with the 49 but can't keep the boost down with the 6262.

Don't want to hear about porting the wastegate hole in the exhaust housing, been there done that. The hole is matched to the pipe that leads to the wastegate. More than 1.25"! Now before someone puts down the gate we sell, I threw a Turbosmart 38mm gate on it to take that out of the equation. Absolutely no difference.

I have gone back and forth between the traditional Turbonetics "air regulator" type of controller plumbed up like the diagram I attached and Turbonetics little billet boost controller that is plumbed with a vented setup per their instructions.

The billet one has a bleed hole on it that supposedly bleeds off boost at higher rpms. I seem to have a little better luck using that one but have to have the knob turned just about all the way out to keep boost below 25lbs.

The thing that scares me about the billet boost controller is there is nothing that would prevent the knob from backing all the way out with vibration. There is a little spring loaded rod that is designed to keep that from happening but I don't trust it.

Will going to a bigger wastegate help or am I really limited by the size of the hole in the turbo exhaust housing? Is it time to go off the headers with the piping to the wastegate?

On the traditional Turbonetics controller, can I drill a bleed hole in one of the plugs in the side of it? Dumb question but just wondering. 6262 is a great turbo just need to reign it in a bit! Thank God for Razors alky system.:biggrin:

 

[bison]

How much tension is on the wastegate via the spring installed in it? This is likely your problem. If you have less backpressure which you would with the 62 turbine you will need less tension on the wastegate spring to control boost. If you are going to rev up higher int he rpm range later you may find the exact opposite will happen when the backpressure gets higher. It may actually lose boost. Ive noticed ive had to go much larger on the wg hole with most externals. One thing you have to keep in mind with more valve surface area on the gate is you are giving the backpressure more to act on. This can cause a problem if the wastegate hole is too small since the valve will start cycling too much since the pressure drop will be too much when the valve cracks open to bleed off boost. If the boost is creeping id try removing tension from the spring first then go to a lighter spring in the gate. That should haelp a lot. Take the control valve out of the picture and plumb directly to the bottom of the gate without any pressure on top and see how much boost you get at your highest rpm.

 

[Eticket]

Mark,
yes, chances are that you're limited by the wastegate hole and/or the flow potential of the 38mm gate (doesn't matter what brand). These new exhaust wheels are very efficient and have created this problem since the F1 style wheels were used in the bigger turbos. The fix is to go to a bigger gate, probably off the header or crossover.

 

[bison]

Mark,
yes, chances are that you're limited by the wastegate hole and/or the flow potential of the 38mm gate (doesn't matter what brand). These new exhaust wheels are very efficient and have created this problem since the F1 style wheels were used in the bigger turbos. The fix is to go to a bigger gate, probably off the header or crossover.

Its funny that you can still get an internal to work on an S/GTQ or HPQ up to about 700hp without external pressure beyond manifold but you get the opposite instead up top. Thats with a 1.1 inch wastegate hole too. Loss of boost from backpressure when you start making power. If the correct spring tension and hole size was used the creeping problem should be eliminated.

 

[Boost231]

time for an ams500

 

[bison]

time for an ams500

Shouldnt be needed yet

 

[Eticket]

Bison, have you tried to run your boost below 700hp levels on a gtq? The handful of cars that I messed with, we couldn't get the boost below 18-19psi or so with the actuator only. I'm sure the heads/cam combo makes a little difference too.

I agree with your lightning of the spring suggestion.. I assumed that he'd already done all of that type of trial. Another trick is to crack the wastegate wide open manually and see if the boost still climbs up to the level. That would confirm the flow restriction anyway.

 

[bison]

Bison, have you tried to run your boost below 700hp levels on a gtq? The handful of cars that I messed with, we couldn't get the boost below 18-19psi or so with the actuator only. I'm sure the heads/cam combo makes a little difference too.

I agree with your lightning of the spring suggestion.. I assumed that he'd already done all of that type of trial. Another trick is to crack the wastegate wide open manually and see if the boost still climbs up to the level. That would confirm the flow restriction anyway.

If you have a GTQ on a 231 ci you are not running less than 20 psi or you are way over turboed unless you are revving to 7000+ rpm. To be honest i dont think i ever tired to run less than about 17. I wasnt concerned with how low i could get it. More worried about it losing boost on top of 3rd. I will hook up the AMS 1000 on mine to get it over the 26psi it is stuck at. Back pressure is high as hell. +1 on the wide open gate to measure restriction.

 

[Slow91z]

I'm having a similar issue...I run alky and lots of boost, so most of the time is doesn't bother me, but when I make a change and want to start tuning from ground zero on pump gas only I can't get my boost below 19 or so.

I have a ATR DP, external gate (It's a big gate over 40mm but I can't remember the exact size.), 67 P-trim turbo. I have the hole in the turbo hogged out to pretty much the same size as the DP.

I'm convinced that the only thing to do is run the Wastegate off the header and block the turbo hole.

 

[JP112_89]

My $.02

I am using a stock puck with the WG hole only laid back from the inside hole.
Also, I am using a HD actuator and Hallman Pro BC. I am not using the "Tee".

I have the boost set a 19#'s and it creeps 1/2-3/4#'s through quarter mile.
Prolly would have boost issues at 25+ but I ain't pushing all that air through my motor.

 

[JP112_89]

I'm convinced that the only thing to do is run the Wastegate off the header and block the turbo hole.

Someone else told me that at the higher boost levels.

 

[murphster]

I think your issue may be the turbonetics controller. I had issues with creep also running an external wastegate off the header.

I was told they don't work well by a friend because the hoses are too small and it can't bleed off fast enough. I think we upgraded the hoses and still ran into creep problems. I was running lower boost but flowing a lot of air.

I went to an Innovative electronic boost controller and no problems.

Here's my setup, plenty of wastegate:

 

[JP112_89]

I think your issue may be the turbonetics controller. :

Prolly right.

 

[kraus]

i have a turbosmart little billet boost controller on my combo below with zero boost creep,now my daughters t has a race gate on the down pipe and the air regulator type valve and the other day i jumped on it and noticed boost set at 20 normally.Was at 25 switched in the one off my car 20 rock solid.The trubosmart valve i have clicks at eac turn forward and backward and its a firm click no chance to vibrate loose...

 

[brian]

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Starting to miss my old TA49 setup........ 6262 ball bearing billet turbo, running one of the downpipes I sell with a 38mm external gate. This setup worked fine with the 49 but can't keep the boost down with the 6262.

Don't want to hear about porting the wastegate hole in the exhaust housing, been there done that. The hole is matched to the pipe that leads to the wastegate. More than 1.25"! Now before someone puts down the gate we sell, I threw a Turbosmart 38mm gate on it to take that out of the equation. Absolutely no difference.

I have a 62-65 DBB. I LOVE the turbo as it related to useable street power and spool. But.... It does not matter "how low" I think I have it turned down to, it still goes to 23 when I keep my foot in it longer than a quick blast.
It initially shows 20 or so, but continues to climb to 23 now matter what. Not exactly boost creep, but, annoying none the less.
I use an HKS 40mm gate off the turbo like the downpipes you have. My wastegate hole is ported over 1 1/2 in.
I may be all wet here.... Maybe this has something to do with the airflow capability of the engine? My car does run high tens, but it still has the stock cam. The car is somewhat light, this is why I mention airflow. But, it seems the only way to accurately control these billet units is with a header mounted gate.

Brian

 

[TR Custom Parts]

No idea what my car would run as I haven't been to the track since 2002! I am running our SE front mount and a 70mm TB. Have a Z06 MAF sensor with a 4" MAF pipe to 4" inlet on the turbo. Turbo has the 2.5" outlet. The motor itself is bone stock with 31,000 miles. Had the pan off to replace rear main seal and valve covers off just to replace with aftermarket units.

On the suggestion from someone on the board I put a stiffer spring in the wastegate (14lb) not sure if that was the way to go or not BUT didn't really make any difference in the boost creep. What I am looking for is a baseline of 20lbs of steady boost and the ability to turn it up when I want to. Seems like the little billet controller that T-netics worked a little bit better than the air regulator type. Have a 130mph power logger run where the max it saw was around 26lbs. Don't plan on going that fast on a regular basis on the street though. Yesterday was pinning the 25lb gauge on the street going less than 100mph. This was with the air reg type.

 

[ROYAL_6]

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[GNVYUS 1]

I'm not a fan of this type of wastegate setup in general. Cars that have the wastegate off the header don't have this issue (given the wastegate is properly sized and working properly). Your issue is why I think it's naive for vendors to sell 44mm gates etc for this inferior setup since it's larger than the I.D. of the tube running from the housing.

The wastegate hole on the header of my talon is WAY larger than 1.5" and my little 38mm Tial keeps the 61mm T4 dead solid. It's not the gate, it's the location.

As someone else mentioned, as the exhaust wheel gets more efficient, you need to evacuate more exhaust so it would make sense that the new turbos are causing a more noticeable problem.

 

[TurboBob]

its been said before, but:

To control the boost you need to control the speed of the turbo, which means limiting the amount of exhaust going thru the turbine.

This is done by allowing the exhaust to bypass the turbine by going thru the wastegate system.

The new turbos have extremely efficient turbines and the new housings are really good too. So if the wastegate is not really efficient, the exhaust would rather go thru the wheel than make that abrupt turn and squeeze thru the wastegate. Jay C had a flapper valve held open and the car still went to 20+.

When you mount the gate on the header (properly) the exhaust is much more inclined to exit thru the wastegate and therefore you can control the boost.

The reason the integral gates and gated downpipes will hold boost in the 20's is that the backpressure in the header is high enough that the exhaust will start to make that turn thru the wastegate.

Bob

 

[TR Custom Parts]

UPDATE! THINK I have things under control now. Put a 7 lb spring in the wastegate and actually can now turn the boost down. Slowly turning it back up. Can only bring the car over 100mph in so many places around here.

No real lag issues either though I am sure the car will benefit from a converter change. 12" 2800 stall right now.