WGA to compressor housing...why? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 11-01-2012, 11:07 PM   #1
Newb
Thread Starter
 
Join Date: Jul 2011
Location: DFW / Jacksonville, NC
Posts: 8
Total Cats: 0
Default WGA to compressor housing...why?

Ok, so I know on internally gated turbos, everyone runs a rubber line from the WGA to the compressor housing to manage pressure. My question is...with the fluxuation provided from heatsoak, intercooler temperature and density changes, why not run the line to measure boost pressure at the intake manifold where it undergoes no further changes before entering the engine? It just seems like you'd want to adjust your wastegate to read the actual pressure you are sending into the motor, and not the pressure that the turbo is creating.

Someone educate me!

-Nate
ApexAlchemist is offline   Reply With Quote
Old 11-01-2012, 11:32 PM   #2
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,192
Total Cats: 2,583
Default

no one runs it to the compressor around here.

if they do, its because they are retarded and haven't seen one of the many many threads we have on this exact topic saying this exact info
18psi is offline   Reply With Quote
Old 11-01-2012, 11:43 PM   #3
Senior Member
iTrader: (1)
 
Join Date: Mar 2010
Location: Bay Area, CA
Posts: 695
Total Cats: 140
Default

look here

There's a better thread somewhere but I can't seem to find it at the moment.
gesso is offline   Reply With Quote
Old 11-01-2012, 11:44 PM   #4
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,192
Total Cats: 2,583
Default

Joes Perez' thread about it is EPIC

Search
18psi is offline   Reply With Quote
Old 11-01-2012, 11:45 PM   #5
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,192
Total Cats: 2,583
Default

18psi is offline   Reply With Quote
Old 11-01-2012, 11:50 PM   #6
Elite Member
iTrader: (6)
 
Join Date: May 2011
Location: Lebanon, TN
Posts: 1,668
Total Cats: 63
Default

My understanding with Joe's was more MBC issues. I though EBC shouldn't matter where its pressure signal is from, within reason. As long as it has enough pressure to open the wastegate when its active. EBC should just maintain whatever you tell it to maintain for preassure. Maybe I missed something.
TorqueZombie is offline   Reply With Quote
Old 11-02-2012, 12:18 AM   #7
Newb
Thread Starter
 
Join Date: Jul 2011
Location: DFW / Jacksonville, NC
Posts: 8
Total Cats: 0
Default

not talking about any sort of boost controllers. yes ive seen the boost sag thread, but im always down for some pampering.

and not only on this forum, but elsewhere, ive seen it a million times, i just didnt know if there was any reason for the wastegate to read pressure at the housing rather than the manifold.
ApexAlchemist is offline   Reply With Quote
Old 11-02-2012, 12:21 AM   #8
Newb
Thread Starter
 
Join Date: Jul 2011
Location: DFW / Jacksonville, NC
Posts: 8
Total Cats: 0
Default

just checked the wastegate signal thread, and i got my answers now thanks guys. mods feel free to delete since i wanted to be a forum idiot and not read carefully enough
ApexAlchemist is offline   Reply With Quote
Old 11-02-2012, 12:22 AM   #9
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,192
Total Cats: 2,583
Default

there is no reason.
draw from manifold.
??????
Profit
18psi is offline   Reply With Quote
Old 11-02-2012, 06:06 AM   #10
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,366
Total Cats: 1,328
Default

Drawing from the manifold will kill the turbo if you run partial throttle in boost. The restriction of the throttle plate means you might be seeing 20-25psi in the pipes, but only 14psi in the manifold. You're liable to overspin the turbo and kill it.

If you're using an MBC, source it from the coldside IC pipes, as God intended.
Savington is offline   Reply With Quote
Old 11-02-2012, 09:56 AM   #11
Junior Member
 
Join Date: Oct 2012
Posts: 125
Total Cats: 10
Default

I've been toying with turbocharged cars for the past 13 years, and never once did I find any reason to run the wastegate reference line from the intake manifold. Wastegate diaphragms do not need to see vacuum, ever.

I've seen several people come up with torn wastegate diaphragms in years past, and almost all had something in common: They were using the intake manifold as their boost reference. Coincidence ? Sure, maybe. These wastegate diaphragms were not built to see vacuum, and one can only assume that exposing them to 20-24inHg for extended periods of time is a shitty idea and practice.

Now another reason (call me crazy if you must) to not use the manifold is the negative effect of having such a drastic change in pressure / vac operate the wastegate. Again, these were built to operate on boost pressure to open, and spring pressure to return the flapper to closed position. By using the intake manifold for a reference, you are pushing and pulling the rubber diaphragm very aggressively as opposed to just letting the spring return operate.


"If you're using an MBC, source it from the coldside IC pipes, as God intended." < Truth.
TheBigChill is offline   Reply With Quote
Old 11-02-2012, 10:08 AM   #12
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,192
Total Cats: 2,583
Default

Makes sense, though I had an iwg referenced from the mani for over 2 years on my 00 with no ill effect on wga.
The part throttle over-boost thing makes sense too, but I measured pressure from coldside, mani, and hotside before with no drastic swings from either place. I guess I didn't do part throttle boost long enough for it to build up? It was a large turbo too maybe that's why.

oh well.
Joes thread breaks down placement perfectly.
Do what it says.
18psi is offline   Reply With Quote
Old 11-02-2012, 10:23 AM   #13
Junior Member
 
Join Date: Oct 2012
Posts: 125
Total Cats: 10
Default

Totally. Like I said, I may have just experienced some coincidental failures, but it still struck me as odd. When something isn't designed to operate in a certain way, I have reservations about doing just that. I mean, ****, how many years have gone by where Garrett, Precision, Turbonetics, etc, all manufactured turbochargers that had a reference ports sticking out of the compressor housing ?
TheBigChill is offline   Reply With Quote
Old 11-02-2012, 04:10 PM   #14
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,366
Total Cats: 1,328
Default

If you have a half-decent intercooler, it doesn't matter - I've tuned Miatas that reference from the hotside on a 1bar spring make 14.6psi at the intake manifold. If your intercooler is garbage and drops 2-3psi, then you're going to want to source post-IC to get that boost back.

Similarly, if you have decent EBC, it doesn't matter. Our EFR kits will source from the hotside because 1. we have good intercoolers, 2. we have EBC, and 3. it's more elegant than a 1/4" wastegate source hose running through the entire engine bay.
Savington is offline   Reply With Quote
Old 11-02-2012, 04:30 PM   #15
Newb
Thread Starter
 
Join Date: Jul 2011
Location: DFW / Jacksonville, NC
Posts: 8
Total Cats: 0
Default

yeah the difference between running in vac and boost seems to be the answer i stumbled across the most. still tons of good info guys i appreciate it. looks like ill be swapping out tonight...may be a PITA cuz for whatever reason my gsp charger didnt have a nipple for the line in the compressor housing. but ill make somethin work with the hot side pipes or something.
ApexAlchemist is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
The deezums Catch Can aidandj Engine Performance 138 10-31-2016 02:32 PM
Need ideas mounting IWG actuator JasonC SBB DIY Turbo Discussion 7 09-23-2015 08:25 PM
MT detectives, help me ID my old POS turbo AlwaysBroken DIY Turbo Discussion 3 09-21-2015 02:44 AM
1991 Turbo Miata partout tottestad Miata parts for sale/trade 18 09-14-2015 08:52 PM
FM 1.8 Mani, Test Pipe, HP+, Injectors Chooofoojoo Miata parts for sale/trade 6 09-13-2015 11:01 AM


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 10:21 AM.