Greddy Kit Making Too Much Boost! - 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 03-10-2009, 10:19 PM   #1
Junior Member
Thread Starter
iTrader: (6)
 
Join Date: Apr 2006
Posts: 259
Total Cats: 0
Default Greddy Kit Making Too Much Boost!

Recently put on a turbo tony downpipe and the car makes 5psi for the most part and makes 7psi the last 1500 to 2000 rpm. Anyone else see this with there car? Just after the downpipe I changed the wategate actuator to a better garrett unit from FM and never set the arm up perfect so it only makes 4psi and still makes 7psi up top. UEGO still reads good for a/f ratio so not sweating it but was curious.
danscreations is offline   Reply With Quote
Old 03-10-2009, 10:24 PM   #2
Elite Member
iTrader: (30)
 
Join Date: Aug 2007
Location: Va Beach
Posts: 7,282
Total Cats: 0
Default

There is no such thing as too much boost. The answer is ALWAYS more boost.


PS. I dont have an answer for you.
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
levnubhin is offline   Reply With Quote
Old 03-10-2009, 10:32 PM   #3
Supporting Vendor
iTrader: (3)
 
Join Date: Jul 2006
Location: San Diego
Posts: 2,864
Total Cats: 487
Default

Maybe you have reallllllllllllllllllllllly late spool
ThePass is offline   Reply With Quote
Old 03-10-2009, 10:37 PM   #4
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,107
Total Cats: 518
Default

ThePass is right, the greedy turbo is huge and is famous for spoiling late
curly is offline   Reply With Quote
Old 03-11-2009, 08:45 AM   #5
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,885
Total Cats: 1,790
Default

Quote:
Originally Posted by curly View Post
ThePass is right, the greedy turbo is huge and is famous for spoiling late

Or maybe that large exhausts are notorious for flowing well and can often overload a small internal wastegate?

maybe something like this:

wastegatge.jpg
Braineack is online now   Reply With Quote
Old 03-11-2009, 09:53 AM   #6
Elite Member
iTrader: (9)
 
Join Date: Aug 2006
Location: Concord, North Carolina
Posts: 4,173
Total Cats: 5
Default

Isn't this called boost creep?
miatamania is offline   Reply With Quote
Old 03-11-2009, 10:37 AM   #7
Junior Member
Thread Starter
iTrader: (6)
 
Join Date: Apr 2006
Posts: 259
Total Cats: 0
Default

Stock greddy wastegate did this and same thing with this bigger better unit (Flyin' Miata : Turbochargers : Parts and upgrades : Adjustable wastegate actuator). I have a manual boost controller that I handn't put on yet but I doubt that would do anything other than allow me to up the boost back to 5psi and then it will problaly spike 8psi or so. Just seems odd any other turboed cars seem to have the opposite problem; spike low and leak down up top.
danscreations is offline   Reply With Quote
Old 03-11-2009, 11:29 AM   #8
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,673
Total Cats: 1,561
Default

Quote:
Originally Posted by danscreations View Post
Just seems odd any other turboed cars seem to have the opposite problem; spike low and leak down up top.
Seems that I've read on multiple occasions that this condition is due to sourcing the boost signal from the hotside.

And the problem you are experiencing is often related to a combination of a small turbine and a small wastegate opening, as alluded to above.
sixshooter is online now   Reply With Quote
Old 03-11-2009, 01:42 PM   #9
Senior Member
iTrader: (5)
 
Join Date: Jan 2008
Location: Central, TX / Bay area, CA
Posts: 1,272
Total Cats: 3
Default

unless your making over 15-16 psi your not running enough boost with that turbo
Gotpsi? is offline   Reply With Quote
Old 03-11-2009, 05:03 PM   #10
Junior Member
iTrader: (1)
 
Join Date: Oct 2007
Location: Utah County
Posts: 128
Total Cats: 0
Default

I have the tony dp on my greddy set up. I see the same thing. I left the waste gate a little loose so it would hold around 5-5.5 psi. But in a 4th gear pull on the freeway it will creep up to 6psi at the top of the rpms. Not quite as much as you are seeing.

Quote:
Originally Posted by Braineack View Post
Or maybe that large exhausts are notorious for flowing well and can often overload a small internal wastegate?
I think this is your answer.
papasmurf is offline   Reply With Quote
Old 03-11-2009, 05:53 PM   #11
Supporting Vendor
iTrader: (3)
 
Join Date: Jul 2006
Location: San Diego
Posts: 2,864
Total Cats: 487
Default

If I were you I would get a MBC - even if you want to run only 5 psi, that will do a better job of holding it at 5 than the wastegate alone. The greddy wastegate gets a bad rap but I've found recently that most of the problems people have with it is either a.) people aren't using a tried and true (and affordable) MBC and b.) they have the wastegate signal coming from the hot side (compressor nipple).
Many have swapped the greddy wastegate out for a "stronger" replacement and not accomplished any difference other than being out $100+.

Please tell us what the rest of your exhaust is like. To be honest, the greddy turbo is larger than a lot of the garret units many are running on these cars. Most people slap a BEGI kit on and immediately get nice spool but for the greddy crew we have to work and tweak things to get that spool down.. with a free flowing n/a exhaust my stock greddy kit was not getting 6 psi until 4700 rpm - that's 2300 from redline, not much more than you are saying. Until then it would act just like you say yours does: it would hold a few psi and then surge up to the 6-ish once I hit the rpm it could spool fully at.
Now, with a BEGI divorced gas downpipe going to a 2.5"->3" expander and then a 3" cat, 3" resonator and then a turn down at the rear axle, plus using MS to tune in more spark advance and a bit leaner a/f ratio in the lower cells to spool the turbo fasterI get 6-7 psi by 3500 and 12 psi by 4250. Much better, still not nearly as soon as the guys like Sav who can get 12 psi by like 3k but then again, he had to spin up to 16 psi to get 230 whp and was at the top of his efficiency range and with our turbos we can get 230 with 12-ish psi and efficiency is great up to 275 whp or so... it's a vicous give and take sort o deal ya know..
So.. what's your exhaust?
ThePass is offline   Reply With Quote
Old 03-12-2009, 12:28 PM   #12
Junior Member
Thread Starter
iTrader: (6)
 
Join Date: Apr 2006
Posts: 259
Total Cats: 0
Default

danscreations is offline   Reply With Quote
Old 03-12-2009, 12:48 PM   #13
Elite Member
iTrader: (28)
 
Join Date: May 2008
Location: St. Augustine FL
Posts: 2,310
Total Cats: 2
Default

HEY dan leave me feedback thanks man................. sorry to thread jack!
p51hellfire is offline   Reply With Quote
Old 03-12-2009, 12:53 PM   #14
Junior Member
 
Join Date: Jul 2006
Posts: 59
Total Cats: 0
Default

This happened to my set up over the weekend just gone and, like you, it was after fitting a 2.5" downpipe. My EBC managed to hold target boost (8psi) upto 6k rpm, then for some reason the boost increased or crept upto 9.3 psi at 7.2krpm. My Link map limit was set to 165kpa otherwise I'm sure boost would have exceeded this figure.

Know idea why

punchdrunk is offline   Reply With Quote
Old 03-12-2009, 01:25 PM   #15
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,673
Total Cats: 1,561
Default

Quote:
Originally Posted by punchdrunk View Post
This happened to my set up over the weekend just gone and, like you, it was after fitting a 2.5" downpipe. My EBC managed to hold target boost (8psi) upto 6k rpm, then for some reason the boost increased or crept upto 9.3 psi at 7.2krpm. My Link map limit was set to 165kpa otherwise I'm sure boost would have exceeded this figure.

Know idea why (No idea why) Know location? No location. Put your info under your name, like everyone else, buddy.

Again, too much exhaust for little bitty wastegate hole.

You open hole now, ok. Add larger flapper, too. Shrimp fried rice $3.99.

People have them ported all the time to stop the creep. Or just expect it to creep due to an inadequate wastegate.

Corky Bell, in his book, said that sometimes two wastegates are necessary or even desirable to relieve excess pressure effectively. But it is cheaper and easier just to enlarge yours.

BTW - Adding a better flowing exhaust doesn't create the problem. It simply exposes a preexisting deficiency. The large delta between the inlet and outlet of the turbine created by the better exhaust is highly a highly coveted situation and means increased efficiency and reduced losses.

You have reached a point where you have found a limiting factor, just like the transmission and diff are only good for so much. Or the intake manifold's flow capacity on the thread about dyno #'s just posted yesterday. There are design limits to every component.
sixshooter is online now   Reply With Quote
Old 03-13-2009, 02:26 AM   #16
Junior Member
Thread Starter
iTrader: (6)
 
Join Date: Apr 2006
Posts: 259
Total Cats: 0
Default

I'll have to add another wastegate IN the exhuast like a C6 Z06...lol
danscreations is offline   Reply With Quote
Old 03-13-2009, 03:01 AM   #17
Supporting Vendor
iTrader: (3)
 
Join Date: Jul 2006
Location: San Diego
Posts: 2,864
Total Cats: 487
Default

If the wastegate flapper for the TD04H-15G is too small and therefore adding a larger exhaust causes boost creap, why then does my 2.5" BEGI Divorced gas DP -> 2.5" to 3" expander -> 3"cat -> 3" glasspack resonator -> turndown at axle hold 10psi from 4k to redline with no creep? Except for the cat my setup is basically a resonated dump pipe like a race car. I have not changed the wastegate nor done anything else that would effect it except use a simple cheap MBC.

Last edited by ThePass; 03-13-2009 at 03:15 AM.
ThePass is offline   Reply With Quote
Old 03-13-2009, 09:34 AM   #18
Senior Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Outside of the Loop-ATL
Posts: 754
Total Cats: 0
Default

Quote:
Originally Posted by ThePass View Post
If the wastegate flapper for the TD04H-15G is too small and therefore adding a larger exhaust causes boost creap, why then does my 2.5" BEGI Divorced gas DP -> 2.5" to 3" expander -> 3"cat -> 3" glasspack resonator -> turndown at axle hold 10psi from 4k to redline with no creep? Except for the cat my setup is basically a resonated dump pipe like a race car. I have not changed the wastegate nor done anything else that would effect it except use a simple cheap MBC.

Your running more boost. Most likely if you tried to run only 5psi you would creep some.
wildfire0310 is offline   Reply With Quote
Old 03-13-2009, 09:56 AM   #19
Junior Member
 
Join Date: Jul 2006
Posts: 59
Total Cats: 0
Default

Quote:
Originally Posted by sixshooter View Post
Again, too much exhaust for little bitty wastegate hole.

You open hole now, ok. Add larger flapper, too. Shrimp fried rice $3.99.

People have them ported all the time to stop the creep. Or just expect it to creep due to an inadequate wastegate.

Corky Bell, in his book, said that sometimes two wastegates are necessary or even desirable to relieve excess pressure effectively. But it is cheaper and easier just to enlarge yours.

BTW - Adding a better flowing exhaust doesn't create the problem. It simply exposes a preexisting deficiency. The large delta between the inlet and outlet of the turbine created by the better exhaust is highly a highly coveted situation and means increased efficiency and reduced losses.

You have reached a point where you have found a limiting factor, just like the transmission and diff are only good for so much. Or the intake manifold's flow capacity on the thread about dyno #'s just posted yesterday. There are design limits to every component.
Thanks for that.

The Link ecu has a way of eliminating boost creep, so I'll have to make the appropriate adjustments. I'll call FM later to get some suggestions for waste gate loop gain settings for the Greddy.
punchdrunk is offline   Reply With Quote
Old 03-13-2009, 10:44 AM   #20
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,673
Total Cats: 1,561
Default

Quote:
Originally Posted by wildfire0310 View Post
Your running more boost. Most likely if you tried to run only 5psi you would creep some.
You beat me to it.
sixshooter is online now   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
LucaCarMods's Boosted Dutch Miata Build! LucaCarMods Build Threads 11 02-14-2016 07:13 AM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
New M62 Miata owner Pist0n Meet and Greet 4 10-01-2015 09:18 PM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 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 12:18 PM.