Ridiculous boost creep on GT28RS turbo?? - LotusTalk - The Lotus Cars Community
 
LotusTalk.com is the premier Lotus Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 12-12-2012, 06:23 PM   #1 (permalink)
Registered User
 
wek120's Avatar
 
Join Date: Mar 2011
Location: Blacksburg, VA
Posts: 513
Ridiculous boost creep on GT28RS turbo??

Picked up a Forcefed 380 kit with the GT2860RS turbo, stock internal wastegate. got it on the car and went to get it tuned, only boost went over 9psi (stock motor) so we stuck a fuel cut at 7psi.

Went back, modified the stock wasegate (made length adjustable and added a pushing spring to assist, dropped the spring load by about 3psi according to an air compressor. Tried that and it took longer to build boost, but still creeped up and hit that fuel cut.

Disconnected the wastegate arm completely and tried that. Even slower to build boost, but it still creeped up and hit the fuel cut at over 7psi, even with the wastegate flap wide open, freely swinging open.

Boost creep is one thing, but this is creeping up to a 7psi fuel cut without even anything attached to the wastegate flap. There is a definite tone difference with the arm all the way open, and arm swings freely, yet it still builds boost with nothing holding the valve shut.

Suggestions?

(wastegate attached on left, wastegate left completely off on right, and excuse the crazy o2 readings)
Attached Images
 

Last edited by wek120; 12-12-2012 at 06:29 PM.
wek120 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-12-2012, 06:38 PM   #2 (permalink)
Registered User
 
Join Date: Apr 2006
Location: Colorado springs CO
Posts: 727
I run 275FF kit gt28r at 8 psi and it hits the blow off value when I shift at 4k. Your gt28rs flows more air. can we see a picture of your setup. I have heard of over boost when the exhaust is wrong. What diameter pipe are you using ?

Last edited by lotus90; 12-13-2012 at 07:13 AM.
lotus90 is offline   Reply With Quote
Old 12-13-2012, 08:16 AM   #3 (permalink)
Registered User
 
kverges's Avatar
 
Join Date: Feb 2005
Location: Dallas
Posts: 1,312
I have had to actually port the internal wastegate hole to get it to control boost at a lower number like 7-8 psi. My belief is that the internal housing simply won't divert enough exhaust gas flow to keep boost under 8 psi
kverges is offline   Reply With Quote
Old 12-13-2012, 08:53 AM   #4 (permalink)
Registered User
 
Join Date: May 2012
Location: Lake Norman, NC
Posts: 256
Go external gate
Sburke is offline   Reply With Quote
Old 12-13-2012, 10:55 AM   #5 (permalink)
Registered User
 
Elige's Avatar
 
Join Date: Jul 2005
Location: El Ayy
Posts: 1,557
Quote:
Originally Posted by kverges View Post
I have had to actually port the internal wastegate hole to get it to control boost at a lower number like 7-8 psi. My belief is that the internal housing simply won't divert enough exhaust gas flow to keep boost under 8 psi
I had to do the same thing on my 2zz/28rs setup.
__________________
05 graphite grey elige with zero mods.
Elige is offline   Reply With Quote
Old 12-13-2012, 01:10 PM   #6 (permalink)
Registered User
 
kverges's Avatar
 
Join Date: Feb 2005
Location: Dallas
Posts: 1,312
I'd port first - an external WG is nice, but a non-trivial effort in parts and fabrication and I easily control boost at 8-9 psi with a ported internal WG.
kverges is offline   Reply With Quote
Old 12-13-2012, 04:14 PM   #7 (permalink)
Registered User
 
wek120's Avatar
 
Join Date: Mar 2011
Location: Blacksburg, VA
Posts: 513
Called Radium and they said they too had issues with it creeping all the way up to 7psi with something like a wide open wastegate.

So heres the situation;
-Go to the work of taking the turbo completely apart and porting the internal gate IN HOPES that boost creep will be reduced far enough down to not have any issues.
-OR somehow fit an external wastegate on the header so it connects to the exhaust and still fits in there.

I just don't want to go to the work of porting the internal gate, then find out it still has a bit of creep, and end up having to get the external gate added in the end.

Because if you think about it, even if it only has ~2psi of creep, that means you have to start 2psi lower through the range just to keep from going past your limit, loosing a lot of useful power through the lower RPM range.

Only problem is adding on the external gate on the ForceFed header, as the pipes join right at the flange... Suggestions?
Attached Images
 

Last edited by wek120; 12-13-2012 at 04:29 PM.
wek120 is offline   Reply With Quote
Old 12-13-2012, 04:28 PM   #8 (permalink)
Registered User
 
Join Date: Jul 2006
Location: Boise, ID
Posts: 392
I'm looking to doing an external wastegate setup on mine.

I wonder if anyone else has done this on the FF kit.
If not, maybe we could collaborate and come up with a common solution.
pro10is4life is offline   Reply With Quote
Old 12-13-2012, 04:41 PM   #9 (permalink)
Registered User
 
Join Date: Apr 2006
Location: Colorado springs CO
Posts: 727
Are you running cat and or muffler? the idea is to reduce the boost and cat and or muffler
will help. Just and idea.
lotus90 is offline   Reply With Quote
Old 12-13-2012, 05:17 PM   #10 (permalink)
Registered User
 
wek120's Avatar
 
Join Date: Mar 2011
Location: Blacksburg, VA
Posts: 513
Yes, running high flow magnaflow cat (surprisingly more restriction is better for this particular issue).

Here is a pic from the drivers side of the side of the header (sorry, header is thermal sprayed, DEI titanium wrapped, then thermal sprayed again, and PTP turbo blanket, so a little hard to see).
As you can see, there would be enough space to have a tube come off at an angle and go into the open space beside the turbo. (as shown by the flexible vacuum hose around 1.66" dia)

Thinking of maybe running a Tial MV-R but gonna be close to 350$

Adding the wastegate would need about a 4" flex pipe to join back to the elbow too.
Anyone know if the 321 stainless steel manifold HAS to have a 321 staninless tube welded on for the wastegate? Only need like 6" of 1.875dia too
Attached Images
  

Last edited by wek120; 12-13-2012 at 06:55 PM.
wek120 is offline   Reply With Quote
Old 12-14-2012, 09:52 AM   #11 (permalink)
Registered User
 
Elige's Avatar
 
Join Date: Jul 2005
Location: El Ayy
Posts: 1,557
Quote:
Originally Posted by wek120 View Post
Because if you think about it, even if it only has ~2psi of creep, that means you have to start 2psi lower through the range just to keep from going past your limit, loosing a lot of useful power through the lower RPM range.
If you port it correctly then you will not have this issue. You can port it without creating a permanent communication through your wastegate.
__________________
05 graphite grey elige with zero mods.
Elige is offline   Reply With Quote
Old 12-14-2012, 02:27 PM   #12 (permalink)
Registered User
 
Join Date: Sep 2010
Location: Milwaukee, WI
Posts: 1,166
Yup...

Either run an external gate (a good Tial gate will have no problem controlling you down very low if you want).

Otherwise porting the internal gate should probably get it to hold reasonable levels. You will still likely never be able to hold something like say 5 psi, but you should be able to keep it at bay below 9. I agree with kverges I would start by porting what you have.
__________________
440bhp E85 2006 Solar Yellow Elise.
The way it should have been delivered from the factory with Honda Power!
WhatsADSM is offline   Reply With Quote
Old 12-14-2012, 04:27 PM   #13 (permalink)
Registered User
 
wek120's Avatar
 
Join Date: Mar 2011
Location: Blacksburg, VA
Posts: 513
The way I see it, if I go to the work of taking the turbo apart and porting the turbo, and it still ends up having a little bit of creep under high load (say 2psi), that means you would have to set your overall boost lower (2psi) so that when it does creep, you don't blow the motor. This basically creates a triangle of lost power (graphing where your boost starts at say 5psi, and finishes at 7psi, you loose 2psi down low sloping up to 0psi up high).

Seeing as how you must run a relatively low boost psi on a stock motor, and I most likely will upgrade in the future, I think the external gate is a best way to go.

Ordered a Tial MV-R and 4" flex pipe, should be here tomorrow. Couldn't find 321 stainless steel tubing in increments as small as 1ft, so will be going with 2" 304 stainless tubing for the pipe coming off the header. Will post pics as we get it on there this weekend or early next week.

The wastegate is watercooled though, which may be a bit excessive, but it was the only Tial 44mm now. Considering the Lotus's rep to cook things in the engine bay, it couldn't hurt. Just need to figure the best way to tap it in.
wek120 is offline   Reply With Quote
Old 12-14-2012, 05:08 PM   #14 (permalink)
Registered User
 
Join Date: Dec 2009
Posts: 76
Simple fix for this...

Hi,
As the guy that engineered and produced The ForcedFed systems, I supply all the gt series exhaust housings with a modified waste gate. We did this from the very first systems in 2005 through to the present.
The 28rs needs this and will maintain 5-6 psi after the mod, even in very cold dense weather. Speak to Kris at DRS if you would like for a confirmation of this.

Pm me if you would like more details. I provide this service at a modest cost, do it in a verticle mill and also provide a mild port of the turbine housing that has proven to aid in power accross the powerband.

I would advise very strongly against cutting the manifold to add an external wastegate. It was not designed to carry the mass of a WG unit, and more importantly it shows a disregard for a system that has literally hundreds of thousands of miles successfully propelling street daily drivers all over the world.

Sincerely, Jim Dunford - DMC Components
DMC Comp is offline   Reply With Quote
Old 12-14-2012, 05:39 PM   #15 (permalink)
Registered User
 
wek120's Avatar
 
Join Date: Mar 2011
Location: Blacksburg, VA
Posts: 513
One reason I bought the kit was because of the high quality manifold. However, I am able to build boost up to OVER 7psi with the wastegate WIDE OPEN flapping in the breeze, all on a stock motor.

I would think porting could only get it down so low. Even with porting the internal wastegate, with the amount of boost it is building with the valve wide open, it seems like carving out as much material in there as you possibly could would still leave at least a little boost creep, especially when you start upgrading the motor and flowing more boost.

How would you suggest adding an external wastegate if one is desired then? Would using 321 tubing and bracing the wastegate work then? (found a source for 321 I think? http://profabrication.com/productDet...&attValID=5750)

Last edited by wek120; 12-14-2012 at 08:16 PM.
wek120 is offline   Reply With Quote
Old 12-15-2012, 02:51 AM   #16 (permalink)
Registered User
 
evansp60's Avatar
 
Join Date: Feb 2006
Posts: 383
READ THIS THREAD!!!!

STAY AWAY FROM "DMC Comp" / "JIM DUNFORD"
evansp60 is online now   Reply With Quote
Old 12-15-2012, 04:56 AM   #17 (permalink)
Registered User
 
Join Date: Apr 2006
Location: Colorado springs CO
Posts: 727
Jim is not only trying To sell him some thing. He is trying provide tech help. Which l for one would like to hear.
lotus90 is offline   Reply With Quote
Old 12-15-2012, 05:09 AM   #18 (permalink)
Registered User
 
evansp60's Avatar
 
Join Date: Feb 2006
Posts: 383
lotus90 - Cavet Emptor!
evansp60 is online now   Reply With Quote
Old 12-15-2012, 06:12 AM   #19 (permalink)
Registered User
 
Join Date: Sep 2010
Location: Milwaukee, WI
Posts: 1,166
Just like to point this out since it has been mentioned by the TS a few times.

Typically boost creep will go away as you set you boost level higher, not get worse.

At low boost levels you are asking the turbo to flow a bunch of exhaust charge around the turbo and not much past the turbine. At higher boost levels you are passing less gasses around the turbo as it takes much more to keep the turbo spinning enough to pump enough air for the engine at high(er) flow rates and high(er) pressure ratios.
__________________
440bhp E85 2006 Solar Yellow Elise.
The way it should have been delivered from the factory with Honda Power!
WhatsADSM is offline   Reply With Quote
Old 12-15-2012, 07:57 AM   #20 (permalink)
Registered User
 
wek120's Avatar
 
Join Date: Mar 2011
Location: Blacksburg, VA
Posts: 513
Yikes, that thread definitely shows his poor business reputation, but if I ported it, I would most likely grab a grinder and do it myself. Still left in the dark as to how the 'correct way' to add a wastegate would be. Have yet to hear back from him either. All of the performance shops I have called said it should be find adding the 304, but just to be on the safe side I think I'll order 321, should I go with the external wastegate.

Still undecided whether or not to go with porting or external gate. Especially since I will be running lower boost for a while to start out with, I think even porting it out as much as I can safely do would still leave a good bit of boost creep, aka lost power down low. I've also heard others with the GT28RS having boost creep problems even up at 20psi. Seems like the better choice is still the external wastegate, but maybe adding some bracing for the wg.
wek120 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  LotusTalk - The Lotus Cars Community > Lotus Discussions > Powertrain (Engine, Transmission, etc) > Forced Induction



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 08:18 PM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.3.2
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.