Begi s4 overboost > looking for advice. - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Prefabbed Turbo Kits A place to discuss prefabricated turbo kits on the market
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools
Old 04-07-2016, 04:52 PM   #1
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2007
Posts: 80
Total Cats: 3
Default Begi s4 overboost > looking for advice.

I am having a hard time figuring out how to troubleshoot an overbooting issue and seek the advice of the community. This subject has been beaten to death but it seems most people get a port and call it a day or go to an external gate. My turbo is already ported and I’d like to avoid going external if possible.

First my car:
01 vvt
Begi S4 kit
Begi separated gases downpipe that flows back into the exhaust
3” exhaust from Abe with a cat and resonator.
Garrett gt2860rs .64ar
Wastegate has already been ported by Begi according to Begi themselves.

I wired the wastegate open and did a 3rd gear pull. The car made 2psi up until ~5k where it creeps to 12+psi verified on boost gauge, megasquirt log, and butt dyno in 3rd gear. With a 7psi actuator with the proper 3 turns of preload the car makes ~15psi. I assume this means either the port isnt capable of pushing out enough exhaust gas or the wastegate’s pipe isnt free flowing enough. Is that accurate? What could other culprits be if any? Attached are 2x pics of how much the flapper opens.

I have seen a few threads on here where people grinded out the exhaust housing entering the wastegate to allow for smoother flow for the exhaust to exit the wastegate. Is that something that is worth looking into? I already have the turbo yanked out of the car at the moment and I plan to take it somewhere to see if they can port the turbo more than it already is if that is a viable option. But short of going to an external setup I am not sure what is worth trying.
Attached Images
File Type: jpg IMG_0232.JPG (841.2 KB, 40 views)
File Type: jpg IMG_0251.JPG (872.8 KB, 42 views)
kiladonut is offline   Reply With Quote
Old 04-07-2016, 04:56 PM   #2
Boosting since 1984
iTrader: (1)
 
stefanst's Avatar
 
Join Date: Sep 2011
Location: Levittown
Posts: 1,198
Total Cats: 68
Default

How about wiring the WG open and check how much boost this nets you? That should be pretty definitive.
stefanst is offline   Reply With Quote
Old 04-07-2016, 04:59 PM   #3
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,359
Total Cats: 1,323
Default

Quote:
Originally Posted by stefanst View Post
How about wiring the WG open and check how much boost this nets you? That should be pretty definitive.
Quote:
Originally Posted by kiladonut View Post
I wired the wastegate open and did a 3rd gear pull. The car made 2psi up until ~5k where it creeps to 12+psi verified on boost gauge, megasquirt log, and butt dyno in 3rd gear.



OP, the best you can do is port the hell out of the wastegate, but you may never be able to run 7psi on that setup. You have the worst possible combination of parts for low boost. Tubular manifold + small A/R Garrett turbine + decent downpipe + big exhaust = boost creep city.

I would seriously consider a swap to an EFR setup before investing the money in an EWG mainfold/downpipe for that turbo. The EFRs have none of these issues, owing to far better wastegate design.
Savington is online now   Reply With Quote
Old 04-07-2016, 05:07 PM   #4
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,174
Total Cats: 2,575
Default

Quote:
Originally Posted by kiladonut View Post

I have seen a few threads on here where people grinded out the exhaust housing entering the wastegate to allow for smoother flow for the exhaust to exit the wastegate. Is that something that is worth looking into? I already have the turbo yanked out of the car at the moment and I plan to take it somewhere to see if they can port the turbo more than it already is if that is a viable option. But short of going to an external setup I am not sure what is worth trying.
this is very important and likely your only non-expensive option.

the path to the wg port is just as important as the port diameter itself.

you can easily do it yourself with a grinder and carbide burr btw.
18psi is offline   Reply With Quote
Old 04-07-2016, 05:09 PM   #5
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,992
Total Cats: 1,457
Default

Install an exhaust restrictor.
aidandj is offline   Reply With Quote
Old 04-07-2016, 05:11 PM   #6
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,174
Total Cats: 2,575
Default

dont' make me ban you

18psi is offline   Reply With Quote
Old 04-07-2016, 05:13 PM   #7
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,992
Total Cats: 1,457
Default

aidandj is offline   Reply With Quote
Old 04-07-2016, 06:09 PM   #8
Elite Member
iTrader: (1)
 
Join Date: Jun 2014
Location: Austin, TX
Posts: 2,843
Total Cats: 271
Default

Girz0r is online now   Reply With Quote
Old 04-07-2016, 06:48 PM   #9
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2007
Posts: 80
Total Cats: 3
Default

Thanks everyone. You guys pretty much confirmed what I thought. I will likely try to grind the housing and if that helps at all. Maybe check to see if any more of the wastegate port itself can be opened up. If that doesn't get me where I want to be I will look into other options. I will post an update on how it goes.
kiladonut is offline   Reply With Quote
Old 04-09-2016, 06:51 PM   #10
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2007
Posts: 80
Total Cats: 3
Default

Just took off the manifold to see what I'm dealing with while I hunt down a carbide burr. Figured I'd give an update before the update. This is my starting point. Going to widen the channel and smooth some of the sharp edges.



Attached Images
File Type: jpg IMG_0257_zpscpxjevg1.jpg (169.9 KB, 234 views)
File Type: jpg IMG_0258_zpsplzklikd.jpg (104.4 KB, 237 views)
kiladonut is offline   Reply With Quote
Old 04-09-2016, 07:58 PM   #11
Elite Member
 
Join Date: Apr 2010
Location: Newcastle, Australia
Posts: 2,638
Total Cats: 25
Default

Im going to go ahead and ask this question again but.. Do you really need it to not creep up top?

do you have insufficient injectors?

Dann
nitrodann is offline   Reply With Quote
Old 04-10-2016, 09:54 AM   #12
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,655
Total Cats: 1,558
Default

Either grind the entrance slope to the WG, let it run 12+psi, or switch to a .86 turbine housing.
sixshooter is offline   Reply With Quote
Old 04-10-2016, 09:58 AM   #13
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,838
Total Cats: 1,787
Default

Quote:
Originally Posted by stefanst View Post
How about wiring the WG open and check how much boost this nets you? That should be pretty definitive.
did we do this yet?
Braineack is offline   Reply With Quote
Old 04-10-2016, 11:40 AM   #14
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2007
Posts: 80
Total Cats: 3
Default

If I didnt have stock rods this wouldnt be an issue. The car creeps to 15-16 psi in 3rd gear and it will get worse in 4th, 5th, and 6th. The end goal assuming I stay with this turbo setup is to run 10-12psi wategate with an MBC set to 12-14psi and not nuke the car at an autocross.

With the wastegate wired opened the car peaked at 12.7psi. With the 7psi actuator hooked up it made 15.x both in 3rd gear (same day/air temp/road). Does it stand to reason that with the actuator opened I should only be seeing 12.7psi? I was previously thinking with the actuator attached there is more exhaust gas trying to escape at once when the flapper opens compared to having it wired opened and it venting the entire time. But really, I could just be way off base.

Would the larger .86 A/R housing fix my problem? Large wategate? I need to read some more about how badly that would hurt spool. I am not a track rat so it might not be a big deal.

It sounds like my options in no particular order are:

1. Pray to turbo kitten for unlikely great porting success
2. EFR
3. External WG
4. Larger housing
5. Build motor
kiladonut is offline   Reply With Quote
Old 04-10-2016, 08:04 PM   #15
Junior Member
 
Join Date: Sep 2013
Posts: 193
Total Cats: 7
Default

Another option is an ewg manifold with a tial 38mm
Shortpersonbk is offline   Reply With Quote
Old 04-11-2016, 10:01 AM   #16
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2007
Posts: 80
Total Cats: 3
Default

I have decided against modifying my current turbine housing any further. Its ported to a point where I don't think any smoothing I do will have a significant impact. That coupled with a few cracks forming I think its best to replace it. I am going to hunt down a .86 a/r housing.

One thing I just discovered was the wastegate baffle. I assumed it was a standard piece but it is actually welded in place and not from Garrett. If I get a new housing is that something I am going to want to make sure is on the new housing? Could that be reducing the flow to the wastegate being another culprit to my boost creep?

This is the piece I am referring to:
BEGi
kiladonut is offline   Reply With Quote
Old 04-11-2016, 10:13 AM   #17
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,838
Total Cats: 1,787
Default

Quote:
Originally Posted by kiladonut View Post
With the wastegate wired opened the car peaked at 12.7psi. With the 7psi actuator hooked up it made 15.x both in 3rd gear (same day/air temp/road). Does it stand to reason that with the actuator opened I should only be seeing 12.7psi?
you should be able to get it to stay at 13psi with the actuator attached. remove some preload.
Braineack is offline   Reply With Quote
Old 04-11-2016, 10:13 AM   #18
Elite Member
iTrader: (1)
 
Join Date: Jun 2014
Location: Austin, TX
Posts: 2,843
Total Cats: 271
Default

Quote:
Originally Posted by stefanst View Post
How about wiring the WG open and check how much boost this nets you? That should be pretty definitive.
Quote:
Originally Posted by Braineack View Post
did we do this yet?
Sooooo...

When are you doing this?
Girz0r is online now   Reply With Quote
Old 04-11-2016, 10:29 AM   #19
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2007
Posts: 80
Total Cats: 3
Default

First off I am an moron because that baffle is on the other side of the housing. That can't be an issue.

I played with preload (even taking it down to no preload) prior to pulling the turbo with basically the same results.
kiladonut is offline   Reply With Quote
Old 04-11-2016, 11:04 AM   #20
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,838
Total Cats: 1,787
Default

the arm must not be able to open it as far.
Braineack is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
1.8 BEGI Turbo Kit, Xedi Engine Management, 3" Exhaust AdrianD2 Miata parts for sale/trade 4 04-03-2016 10:27 PM
1.8L BEGi turbo system. Mani/DP, GT2554R, #3 intercooler and pipes, oil/water lines dwink Miata parts for sale/trade 5 01-17-2016 10:23 PM
BEGi 1.8 EWG Exhaust Manifold, T3/T4, Ceramic Coating nickt93 Miata parts for sale/trade 4 08-13-2012 10:39 PM
Turbo car part out, torsen, flex, hydra, turbo and more da chop Miata parts for sale/trade 30 10-14-2011 09:21 PM
FS:Fm msm exhaust and begi Separated Gases downpipe Marlond Miata parts for sale/trade 0 03-23-2008 04:10 PM


Thread Tools

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 Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 12:20 PM.