home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > maintenance & nonperformance

Reply
 
Thread Tools Display Modes
Old 10-13-2016, 03:24 PM   #1
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default Anyone experience terrible boost creep on the 13c?

93 244+T, LH2.4, 2.5" straightpipe, iPd turbo cam, m47

I've noticed that with my 13c, especially in the colder weather, the boost creep is terrible. I can feel the wastegate open at the desired 7psi but if I lay on it and wrap out a gear it will spike to 10-11psi.

I have my MBC set to about 10 psi and it creeped to almost 15psi as I approached 5k so I had to feather the throttle to avoid knock.

My 'theory' behind this is that the wastegate hole is much too small to evacuate sufficient exhaust gasses to regulate boost levels. I haven't taken measurements, but the puck is of adequate size. Underneath the puck, however, is MUCH smaller than the puck. I'm assuming if I were to port this hole to be a similar size to that of a 15g, the creep would go away. I had no spike on my 15g.

Anyone else experience this?
__________________
Current
-93' 244 m47-iPd sways, 13c, iPd cam, 2.5” straight pipe
-93' 245 m47-iPd sways, T-cam
Past
-80' 242gt m46-
-88' 245 m47-Welded diff, gutted, 13g

Quote:
Originally Posted by Jack View Post
spill it MClovin and WTF happens to your glasses you piece of ****..
PromiseRing is online now   Reply With Quote
Old 10-13-2016, 03:38 PM   #2
JohnMc
PV Abuser
 
JohnMc's Avatar
 
Join Date: May 2004
Location: St. Louis
Default

Yeah, it can happen. Esp if there is a more open exhaust behind the turbo.
__________________
'63 PV Rat Rod
'93 245 16VT Classic #1141
JohnMc is offline   Reply With Quote
Old 10-13-2016, 03:41 PM   #3
All Volvo
Board Member
 
Join Date: Apr 2016
Default

and with chilled air and a high-flow intake
All Volvo is offline   Reply With Quote
Old 10-13-2016, 03:45 PM   #4
JohnMc
PV Abuser
 
JohnMc's Avatar
 
Join Date: May 2004
Location: St. Louis
Default

Waaay back in the day I broke my M47 on the first really crisp fall day. I'd been hammering it all summer, no issues. Some cold air, a little boost spike, and 3rd gear disappeared into bits.
JohnMc is offline   Reply With Quote
Old 10-13-2016, 04:21 PM   #5
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Quote:
Originally Posted by JohnMc View Post
Waaay back in the day I broke my M47 on the first really crisp fall day. I'd been hammering it all summer, no issues. Some cold air, a little boost spike, and 3rd gear disappeared into bits.
Oh great. Looking forward to that one
PromiseRing is online now   Reply With Quote
Old 12-18-2016, 05:19 AM   #6
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

I half ass ported the wastegate hole with some $13 Amazon carbide burrs and it's much better. The roads are wet so I'm having trouble keeping traction and bringing it up towards redline in second.

Will see how it maintains boost when the roads are dry and I can get traction.
PromiseRing is online now   Reply With Quote
Old 12-18-2016, 07:27 PM   #7
dl242gt
Can play the blues
 
dl242gt's Avatar
 
Join Date: Jun 2002
Location: S NJ, a suburb of Phila.
Default

I bought a modified wastegate that was worked on for flow long ago from cherry turbos. This was for a T3. He told me at that time that if the modified wastegate didn't fix my boost creep then the next step was to enlarge the port in the turbine. Fortunately it did.

Or you can update to a larger turbine pretty reasonable with a mitsu turbo. Like the turbo from the 850 people use here. 15g I think.
__________________
Dave,
1982 242 turbo. MVP coilover front and rear adjustable suspension. Bilstein HD. IPD 25/25 bars. 3" rusty MVP exhaust. Cosworth Sierra hot side T3 .48 with upgraded stock .42 compressor. Ported 90+. D&F Performance flowed 405 with enem V15 turbo cam, Clanky worn True Track diff. Flat hood 1979 242 front.

1993 245 Classic, 411k miles, enem V15. 5spd. IPD bars and chassis braces. New Simons sport exhaust from Scandix.
dl242gt is offline   Reply With Quote
Old 12-18-2016, 11:07 PM   #8
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Quote:
Originally Posted by dl242gt View Post
I bought a modified wastegate that was worked on for flow long ago from cherry turbos. This was for a T3. He told me at that time that if the modified wastegate didn't fix my boost creep then the next step was to enlarge the port in the turbine. Fortunately it did.

Or you can update to a larger turbine pretty reasonable with a mitsu turbo. Like the turbo from the 850 people use here. 15g I think.
Good info here. Cherry turbos made the wastegate, link?

Update again: did a 2nd gear pull to redline and it still creeped to 13psi.

I know this 13c is small and useless for power, but it is in near new condition. No play, no smoke, nothing. I keep it on here for reliability.

Would a bigger turbine wheel cause it to creep less?
PromiseRing is online now   Reply With Quote
Old 12-19-2016, 03:22 AM   #9
Duder
His Dudeness, El Duderino
 
Duder's Avatar
 
Join Date: Dec 2009
Location: Torrance, CA
Default

Quote:
Originally Posted by PromiseRing View Post
Would a bigger turbine wheel cause it to creep less?
Yes. Although a more general answer is that a higher flowing turbine will reduce creep, so either a larger turbine housing A/R or a wheel that flows more with an appropriate housing. Higher flow can be due to larger wheel inducer diameter, larger trim, aerodynamic design, or a combination thereof. You can use turbine maps to gage the flow capacity.

Higher turbine flow means less wastegate flow is needed to maintain the same boost pressure, assuming the compressor is unchanged. Your wastegate is choking, meaning you either need a higher flowing wastegate orifice or a higher flowing turbine that consumes more flow to get to the same shaft speed thereby reducing the required wastegate flow.

You can also just make your post-turbine exhaust more restrictive! Or port the crap out of the turbine housing inlet and wastegate passage.
Duder is offline   Reply With Quote
Old 12-19-2016, 01:29 PM   #10
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Quote:
Originally Posted by Duder View Post
Yes. Although a more general answer is that a higher flowing turbine will reduce creep, so either a larger turbine housing A/R or a wheel that flows more with an appropriate housing. Higher flow can be due to larger wheel inducer diameter, larger trim, aerodynamic design, or a combination thereof. You can use turbine maps to gage the flow capacity.

Higher turbine flow means less wastegate flow is needed to maintain the same boost pressure, assuming the compressor is unchanged. Your wastegate is choking, meaning you either need a higher flowing wastegate orifice or a higher flowing turbine that consumes more flow to get to the same shaft speed thereby reducing the required wastegate flow.

You can also just make your post-turbine exhaust more restrictive! Or port the crap out of the turbine housing inlet and wastegate passage.
All good info above! Thanks. As for the bolded section, that's kind of what I did. I ported the wastegate area a reasonable amount, but the problem persists. I'm sure I could port it more heavily, but it was my first time ever using a die grinder and carbide burrs. I will upload a picture so everyone can laugh

Making the exhaust more restrictive should always be a no-go I thought. Yes it will help control boost levels, but surely it will hurt performance? It's a 2.5" straight pipe to a straight through ultra quiet resonator.
PromiseRing is online now   Reply With Quote
Old 12-19-2016, 01:40 PM   #11
culberro
Ronald Culberbone III
 
culberro's Avatar
 
Join Date: Feb 2010
Location: Portland, OR
Default

I enlarged the wastegate hole on my 13c with a 3/4in drill (pretty sure that was the size), and then a bit more with carbide burs. I then made a nice entry way to help the exhaust gases make the 90deg turn into it. I minimally ported the inlet to the turbine housing, and then matched up the manifold. It's rock steady at stock boost to 15psi... well mostly rock steady. I get about 1psi of boost creep....

Engine is a b230ft with a 2.5in exhaust, so you'll probably have a bit more exhaust energy from the higher compression pistons.
culberro is online now   Reply With Quote
Old 12-19-2016, 06:09 PM   #12
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Quote:
Originally Posted by culberro View Post
I enlarged the wastegate hole on my 13c with a 3/4in drill (pretty sure that was the size), and then a bit more with carbide burs. I then made a nice entry way to help the exhaust gases make the 90deg turn into it. I minimally ported the inlet to the turbine housing, and then matched up the manifold. It's rock steady at stock boost to 15psi... well mostly rock steady. I get about 1psi of boost creep....

Engine is a b230ft with a 2.5in exhaust, so you'll probably have a bit more exhaust energy from the higher compression pistons.
I was pretty conservative with the burrs, maybe I should open it up a bit more? Worst case I'm out a $60 turbo.
PromiseRing is online now   Reply With Quote
Old 11-09-2017, 11:55 AM   #13
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Have you it’s ever noticed how hilariously small the wastegate hole on a 13c is in comparison to the actual size of the puck? It’s nearly half the size.

Then if you look at an hl turbo like the 13g/15g, they’re much much bigger. I’m tempted to install this 13g but do not have a proper wastegate bracket. I’m almost positive that the larger wastegate would keep boost more steady.

I could also go at the 13c hotside a little more with the carbide burrs. I initially feared ****ing it up but I’m not too worried anymore.

Anyone have pictures of their ported td04s? id like to see how much I can take off.
PromiseRing is online now   Reply With Quote
Old 11-09-2017, 01:56 PM   #14
esmth
dirty swede
 
esmth's Avatar
 
Join Date: Jul 2016
Location: Massachusetts
Default

Mine definitely creeps if i'm in boost for more than 15 seconds. I loosened my waste gate a little and it helped a tiny bit
__________________
1991 244 +T LH2.4 m46 280k miles with B cam & STS cam gear adv 4*, 954 fuel & 207 ezk tuned with Ostrich, 350cc EV6 white injectors, 2.5" exhaust w/ magnaflow straight-through, SLC free wideband
esmth is offline   Reply With Quote
Old 11-09-2017, 04:06 PM   #15
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Quote:
Originally Posted by esmth View Post
Mine definitely creeps if i'm in boost for more than 15 seconds. I loosened my waste gate a little and it helped a tiny bit
There’s no preload adjustment on a 13c. Not on mine at least. I don’t think it’s an issue of opening far enough, but that the hole is simply too small.
PromiseRing is online now   Reply With Quote
Old 11-09-2017, 06:25 PM   #16
ZVOLV
<Master Tech>
 
ZVOLV's Avatar
 
Join Date: Nov 2002
Location: California
Default

^^^^
Some are adjustable, some are not.
__________________
No Start Thread
ZVOLV is offline   Reply With Quote
Old 11-09-2017, 06:35 PM   #17
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Quote:
Originally Posted by ZVOLV View Post
^^^^
Some are adjustable, some are not.
Weird. Mine is not. It doesn’t seem like there’s much preload on it anyway though. I just think that since I’ve increased the efficiency of the intake and exhaust so much, it has trouble relieving boosts.
PromiseRing is online now   Reply With Quote
Old 11-10-2017, 11:22 AM   #18
Ryan_R
Board Member
 
Join Date: May 2006
Location: Athens, OH
Default

I'm running a Kinugawa actuator set to about 7-8psi. No boost creep that I've noticed.

I did, for giggles, try shimming the factory waste gate with a couple washers. I got a one or two extra psi over the 5psi opening pressure, but it kept the actuator arm from opening the waste gate fully, so there was crazy boost creep! A couple mm made all the difference.

I have a spare Kinugawa actuator arm here. I could see if it has more travel than the factory arm. Maybe that's part of the restriction?

-Ryan
__________________
Athens, OH
1987 245
1989 245 GL
1989 745 GLE
1991 745 --Regina powered B234F!
1995 945T -- Mildly modded
https://people.ohio.edu/ridgely/e-code.htm/
Ryan_R is offline   Reply With Quote
Old 11-10-2017, 11:41 AM   #19
PromiseRing
We don't even like Volvos
 
Join Date: Feb 2014
Location: Missouri
Default

Quote:
Originally Posted by Ryan_R View Post
I'm running a Kinugawa actuator set to about 7-8psi. No boost creep that I've noticed.

I did, for giggles, try shimming the factory waste gate with a couple washers. I got a one or two extra psi over the 5psi opening pressure, but it kept the actuator arm from opening the waste gate fully, so there was crazy boost creep! A couple mm made all the difference.

I have a spare Kinugawa actuator arm here. I could see if it has more travel than the factory arm. Maybe that's part of the restriction?

-Ryan
It could be. I really just attributed it to the small hole. But who knows; it may not be opening far enough.

If you don't mind having a look that would be awesome.
PromiseRing is online now   Reply With Quote
Reply

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 On

Forum Jump


All times are GMT -4. The time now is 01:46 AM.

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.