Maximum boost v. external wastegate spring - 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 09-20-2012, 12:56 AM   #1
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default Maximum boost v. external wastegate spring

Alright well i have a bit of an issue.

I leave for the GRM $2012 Challenge a week from today. Well... 6 days from the time you read this, probably.

I ordered a 10psi spring for my Turbosmart 38mm EWG. Unfortunately, i done fucked up and didn't notice that it was for the new style smaller wastegate, and i have the older style that requires bigger springs.

SO.

I'm stuck with my 7psi spring for the time being.

The internet would have me believe that you should never exceed 200% of your wastegate spring. Or 300%, depending on which forums you read.

300% is ok.
200% is not.

In the event that strange things start to happen much past 200%, i need some guidance on how to overcome this limit in a safe-ish and controllable manner. Ordering another spring is not a possibility, as the spring would not arrive in time without paying an inordinate amount in shipping charges. (Which, i'm NOT doing for a $26 part.)

How boost is currently being controlled:

Single port hookup. (Bottom portion to MBC, top portion vented.)
Ball/spring MBC
Using reference port on compressor. (Yes, i've read the threads that tell me to use "Port B" instead. I'll do so when i start to see drop.)

Sooo...

1) Is the 200% rule a myth?
2) If it's NOT, are there other ways to increase boost past it safely? I've seen references to a dual-port hookup like so:





Target boost is in the 20-25psi range. Higher if i have the fuel.
Attached Thumbnails
Maximum boost v. external wastegate spring-wstgate.gif  
concealer404 is offline   Reply With Quote
Old 09-20-2012, 08:36 AM   #2
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,093
Total Cats: 90
Default

The issue with it is normally once you get to such high pressures the back pressure in the exhaust is enough to overcome the force of the boost pressure pushing on the diaphragm and the spring. If this was an IWG I'd say just go to the hardware store and buy a pull spring to use as a helper spring, but since its an external You could just shim it, or you could see if a spring from the hardware store would work.
Leafy is offline   Reply With Quote
Old 09-20-2012, 09:17 AM   #3
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

Who cares what percentage you're at? Worst case it gets blown open, which will do nothing more than make boost drop. Keep raising it til it wont go higher. Leave it there.
18psi is offline   Reply With Quote
Old 09-20-2012, 09:51 AM   #4
mkturbo.com
iTrader: (24)
 
shuiend's Avatar
 
Join Date: May 2006
Location: Charleston SC
Posts: 13,778
Total Cats: 1,106
Default

I was running 17psi with a 6psi spring in my external Tial wastegate and it was fine. I am planning on upping that to about 24psi on the 6psi spring once I get the car running again.
shuiend is offline   Reply With Quote
Old 09-20-2012, 10:24 AM   #5
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by 18psi View Post
Who cares what percentage you're at? Worst case it gets blown open, which will do nothing more than make boost drop. Keep raising it til it wont go higher. Leave it there.
Right, but once i reach the point that it gets blown open, the car is faster at the point on the boost controller BEFORE it starts blowing **** open. I can run 14psi on this wrong 10psi spring that's in the car right now, but it's WAY slower than 14psi on the correct 7psi spring, because i'm blowing the ******* thing open like crazy.

Characteristics of this motor tell me that it's rather unlikely that i'll be able to sustain 300% spring rating.

Of COURSE i'm going to try it anyways. This thread is about ways to "stretch" farther than you should be able to. I don't care about the percentage, i'm just trying to milk your brains for ways to combat the wastegate blowing open if that starts to happen.



This may all be a moot point. The Sales Executive at Turbosmart responded to an email concerning the part numbers of these springs and says she should be able to get me a 14psi spring in time. They have AWESOME service over there.
concealer404 is offline   Reply With Quote
Old 09-20-2012, 10:25 AM   #6
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by Leafy View Post
The issue with it is normally once you get to such high pressures the back pressure in the exhaust is enough to overcome the force of the boost pressure pushing on the diaphragm and the spring. If this was an IWG I'd say just go to the hardware store and buy a pull spring to use as a helper spring, but since its an external You could just shim it, or you could see if a spring from the hardware store would work.
I'm not looking for unlimited control at 40psi on a 7psi spring... just something to stretch another 2-3psi if i need to. Is the method i posted something that might do such a thing?
concealer404 is offline   Reply With Quote
Old 09-20-2012, 10:30 AM   #7
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

If the 10psi spring isn't for your specific ewg then its not a 10psi spring. Meaning it could be a 4psi spring for all you know.
And when it blows open it doesn't blow all the way open and drop boost more than when it was on a lower spring within its range of operation, dunno wtf you're talking about there.

But if they get you the right spring, cool beans.
18psi is offline   Reply With Quote
Old 09-20-2012, 10:41 AM   #8
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by 18psi View Post
If the 10psi spring isn't for your specific ewg then its not a 10psi spring. Meaning it could be a 4psi spring for all you know.
And when it blows open it doesn't blow all the way open and drop boost more than when it was on a lower spring within its range of operation, dunno wtf you're talking about there.

But if they get you the right spring, cool beans.
I realize this... I'm saying that even if i were to be able to push 20psi on the "10psi" spring for example, it would be slower than 14psi on the 7psi spring. The spool up gets REALLY bad, and this car doesn't "hit" until boost has stabilized at the target. (Probably due to some other weirdness, it's something i've tried to figure out for years.) That may be for a different thread, though.


Either way... at the worst case scenario at this point, the 7psi spring goes back in. And i'm just trying to figure out how to get another couple psi out of it before running into weirder/slow spool. Best case scenario, i get the 14psi spring and i have no issues at all.

Just so we're on the same page, this isn't a BP.
concealer404 is offline   Reply With Quote
Old 09-20-2012, 10:45 AM   #9
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

Quote:
Originally Posted by concealer404 View Post
I realize this... I'm saying that even if i were to be able to push 20psi on the "10psi" spring for example, it would be slower than 14psi on the 7psi spring. The spool up gets REALLY bad, and this car doesn't "hit" until boost has stabilized at the target. (Probably due to some other weirdness, it's something i've tried to figure out for years.) That may be for a different thread, though.


Either way... at the worst case scenario at this point, the 7psi spring goes back in. And i'm just trying to figure out how to get another couple psi out of it before running into weirder/slow spool. Best case scenario, i get the 14psi spring and i have no issues at all.

Just so we're on the same page, this isn't a BP.
ummmmm, WAT

No.
18psi is offline   Reply With Quote
Old 09-20-2012, 10:47 AM   #10
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,093
Total Cats: 90
Default

Yes because your spring is too short and even with the boost reference un plugged or plugged into the wrong hole there is nothing keeping the flapper closed at rest.
Leafy is offline   Reply With Quote
Old 09-20-2012, 10:50 AM   #11
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

Quote:
Originally Posted by Leafy View Post
Yes because your spring is too short and even with the boost reference un plugged or plugged into the wrong hole there is nothing keeping the flapper closed at rest.
How is a 10psi spring holding down the flapper worse than a 7psi spring?

Are you guys high?

omfg
18psi is offline   Reply With Quote
Old 09-20-2012, 10:53 AM   #12
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,093
Total Cats: 90
Default

Because the 10psi spring is for a different waste gate and is shorter than the 7psi spring.
Leafy is offline   Reply With Quote
Old 09-20-2012, 10:58 AM   #13
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

If its for a different wastegate ITS NOT A 10PSI SPRING.
Therefore it has nothing to do with this discussion unless both of you think its still a 10psi spring.

apple =/= banana

Ok. Stepping out of this thread. Its going full retard.
18psi is offline   Reply With Quote
Old 09-20-2012, 11:14 AM   #14
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by 18psi View Post
ummmmm, WAT

No.
Ummmmm.... Yes.

It's not all about max boost. 20psi isn't helpful if it takes 3-4 seconds to reach that point on a weak spring vs. the 14psi i can reach in literally less than half a second on the "correct" spring. I realize the 10psi spring isn't really a 10psi spring, hence the quotes.

Like i said in that very post that you quoted, the car doesn't actually really MOVE until a split second AFTER it hits target boost. It's not fast until it finishes slamming up to maximum. I don't care about your experiences with your Miata, or turbo cars you've had, or any of that ****. This doesn't even mirror my experiences with my other turbo cars.

It's just what this car does, and i have no idea why. I have to work with it, and this is why i'm asking my questions.

Why is this relevant? Because if spool goes out the ******* window @ 20-24psi on the 7psi spring, the car will probably be faster at a lower boost amount with proper control.


So yet again, let's keep it simple and go back to the very first questions i asked in the original post instead of arguing about what MY car does.

SIMPLY PUT: Is the "dual port" method of hookup effective in giving another couple psi of headroom?
concealer404 is offline   Reply With Quote
Old 09-20-2012, 11:17 AM   #15
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by Leafy View Post
Yes because your spring is too short and even with the boost reference un plugged or plugged into the wrong hole there is nothing keeping the flapper closed at rest.
Quote:
Originally Posted by 18psi View Post
How is a 10psi spring holding down the flapper worse than a 7psi spring?

Are you guys high?

omfg
Quote:
Originally Posted by Leafy View Post
Because the 10psi spring is for a different waste gate and is shorter than the 7psi spring.
Quote:
Originally Posted by 18psi View Post
If its for a different wastegate ITS NOT A 10PSI SPRING.
Therefore it has nothing to do with this discussion unless both of you think its still a 10psi spring.

apple =/= banana

Ok. Stepping out of this thread. Its going full retard.


Ok, stop with the "10psi" spring. It's not relevant other than to show what happens with my car with a spring that's too weak. I thought i made that pretty clear earlier, but apparently not.
concealer404 is offline   Reply With Quote
Old 09-20-2012, 11:17 AM   #16
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,093
Total Cats: 90
Default

No. Just run the standard config. Its not going to effect spool, it'll just effect the max boost you can run and spool if you're trying to push past the cracking limit of your current wastegate spring setup.
Leafy is offline   Reply With Quote
Old 09-20-2012, 11:19 AM   #17
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

Quote:
Originally Posted by concealer404 View Post
Ummmmm.... Yes.

It's not all about max boost. 20psi isn't helpful if it takes 3-4 seconds to reach that point on a weak spring vs. the 14psi i can reach in literally less than half a second on the "correct" spring. I realize the 10psi spring isn't really a 10psi spring, hence the quotes.

Like i said in that very post that you quoted, the car doesn't actually really MOVE until a split second AFTER it hits target boost. It's not fast until it finishes slamming up to maximum. I don't care about your experiences with your Miata, or turbo cars you've had, or any of that ****. This doesn't even mirror my experiences with my other turbo cars.

It's just what this car does, and i have no idea why. I have to work with it, and this is why i'm asking my questions.

Why is this relevant? Because if spool goes out the ******* window @ 20-24psi on the 7psi spring, the car will probably be faster at a lower boost amount with proper control.


So yet again, let's keep it simple and go back to the very first questions i asked in the original post instead of arguing about what MY car does.

SIMPLY PUT: Is the "dual port" method of hookup effective in giving another couple psi of headroom?
Simply put: NO..
Dual port increases response not increases pressure. The spring increases pressure.

And Its not my opinion with my cars, its a ******* FACT.

All the bullshit you spouted off about onset, yadda yadda yadda is pretty ******* retarded since we're comparing a 7psi spring to a ???psi spring.

Bottom line, throwing away all the full on retard bullshit, either wait for the new spring or crank it up with the 7psi "correct" spring, or go to a hardware store and pick out a secondary spring and try to crank it up that way til your new one comes.

I'm actually trying to help you here, not just mouthing off. Holy ****
18psi is offline   Reply With Quote
Old 09-20-2012, 11:20 AM   #18
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by Leafy View Post
No. Just run the standard config. Its not going to effect spool, it'll just effect the max boost you can run and spool if you're trying to push past the cracking limit of your current wastegate spring setup.
..... WHAT THE ****.


That's exactly what i'm asking. IS IT EFFECTIVE IN HELPING TO PUSH PAST THE LIMIT OF MY WASTEGATE SPRING SETUP.

Jesus ******* christ.


I mean, i guess i got my answer out of that, but holy **** my forehead is bruised right now.
concealer404 is offline   Reply With Quote
Old 09-20-2012, 11:22 AM   #19
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

It is a FACT that leafy is a ******* retard and pulls complete and utter bullshit out of his *** with every one of his posts.

I would quote all the retardation but that would take a day or two.
18psi is offline   Reply With Quote
Old 09-20-2012, 11:24 AM   #20
Elite Member
Thread Starter
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by 18psi View Post
Simply put: NO..
Dual port increases response not increases pressure. The spring increases pressure.

And Its not my opinion with my cars, its a ******* FACT.

All the bullshit you spouted off about onset, yadda yadda yadda is pretty ******* retarded since we're comparing a 7psi spring to a ???psi spring.

Bottom line, throwing away all the full on retard bullshit, either wait for the new spring or crank it up with the 7psi "correct" spring, or go to a hardware store and pick out a secondary spring and try to crank it up that way til your new one comes.

I'm actually trying to help you here, not just mouthing off. Holy ****
LOL, nice edit. I'll tone it down, too, then.

For the lasttime, i'm not comparing a 7psi spring to a ???psi spring. I was using the example of the ???psi spring being pushed past what it can actually handle to show what i'm trying to avoid.

As i said, with MY car, and i don't give a **** about what your cars do (Or my Miata), once i exceed what the spring can handle, it's slow as ****. As stated, it's NOT all about max PSI. I really don't know how to make that any more clear. Feel free to get mad about it.

I appreciate the bolded portion.

Now you and Leafy can fight to the death over who is right, since you're disagreeing.



Anyways, now for a question about the dual port... I'm afraid i don't understand how it works if it has no bearing on max boost you can possibly run. When you hook up the top port, it works WITH the spring to keep the diaphragm compressed. Asking purely because i don't know: How would this NOT help to increase max boost?
concealer404 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
15x10 - 15x11 6UL @ 949 Racing emilio700 Wheels and Tires 151 06-02-2017 03:36 PM
LucaCarMods's Boosted Dutch Miata Build! LucaCarMods Build Threads 11 02-14-2016 07:13 AM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
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 01:34 AM.