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Old 07-15-2008, 03:19 AM   #1
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Default GT2554 spool is horrible

I've got a 96 with a BEGI log manifold, GT2554, BEGI seperate downpipe, hollow stock cat and 2.25" racing beat exhaust. The spool seems a lot shittier than it should be...

with the actuator arm tightened all the way:

5psi at 2600rpm
10psi at 3400rpm
15psi at 3800rpm

i dont have a preturbo leak, actuator arm is not opening prematurely. This can't be normal right?
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Old 07-15-2008, 03:23 AM   #2
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isnt the 2554 one of the fastest spooling turbo's out there? When people talk about them, its usually the turbo with "no lag, instant power, etc"......so ya, Im going to say something is wrong.....
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Old 07-15-2008, 03:32 AM   #3
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You're trying to achieve 15PSI on the stock wastegate can alone, and complaining about how long it takes?







.
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Old 07-15-2008, 04:07 AM   #4
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Joe, EBC is hooked up at 100% DC throughout the table. i've also tried it with the actuator can pressure line completely unconnected so it never sees any pressure. This is the fastest it will spool, should i be using a different can?
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Old 07-15-2008, 08:44 AM   #5
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regardless of whether the actuator line gets pressure or not the can you are using may be too weak to hold the flapper door from blowing open. I thought I had a boost leak on my begi/2554 but turned out to be that. tested by locked in arm in place with a pair of vicegrips and then being very careful going for a test drive. boost was instant so i knew that was the problem. i tightened the actuator arm all the way down and that made a huge improvement. yours may be a lil weaker than mine.

i think the flapper door blowing open so easily might have something to do with BEGi porting the turbos. we need more flow out the wastegate to eliminate boost creep so that's what we get. if you want to have your cake and eat it too it may be necessary to go to a stronger actuator.
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Old 07-15-2008, 09:28 AM   #6
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Quote:
Originally Posted by 18psi View Post
isnt the 2554 one of the fastest spooling turbo's out there? When people talk about them, its usually the turbo with "no lag, instant power, etc"......so ya, Im going to say something is wrong.....
were you expecting 15psi at 2600RPM.....that's undrivable. I don't see the issue. 15psi around 3800rpm sounds about right with an exhaust that's not designed to flow good.
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Old 07-15-2008, 10:00 AM   #7
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i see 7ish psi @ 3k rpm.....so i am on par with you (i have no boost controller).
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Old 07-15-2008, 10:47 AM   #8
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I see 10psi at 3000 rpm on my T25.

I think his exhaust is the culprit.
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Old 07-15-2008, 10:54 AM   #9
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Stock hollow cat and 2.25" exhaust, chaaaa ching motherfurcker!!!!
You probably gutted the stock cat yourself didn't you? This causes a massive restriction unless you honed the damn thing. Get a test pipe in there and you should see half of your problem go away. Get a real exhaust from Jason and do what Paul says in regards to the WG actuator, I don't know this from experience but he has never steered anyone wrong.
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Old 07-15-2008, 11:34 AM   #10
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simple test:
1. set overboost cut to 15 psi
2. remove vacuum line from wastegate actuator and plug vac line.
3. log that bish.
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Old 07-15-2008, 04:47 PM   #11
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Paul, when you say instant, you make 12psi by what rpm? i have the arm tightened down all the way and you need a gorilla to get it to move, but i'll check again with the vice grip trick.

YS8, this is what i did to get the spool numbers i listed above.


Can my 2.25" exhaust really be the culprit by that much, or am i just expecting too much by all this "instant boost" talk?
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Old 07-15-2008, 04:50 PM   #12
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Quote:
Originally Posted by compuatic View Post
Can my 2.25" exhaust really be the culprit by that much, or am i just expecting too much by all this "instant boost" talk?

plus the gutted stock cat....most definitely.
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Old 07-15-2008, 04:51 PM   #13
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Quote:
Originally Posted by compuatic View Post
Paul, when you say instant, you make 12psi by what rpm? i have the arm tightened down all the way and you need a gorilla to get it to move, but i'll check again with the vice grip trick.

YS8, this is what i did to get the spool numbers i listed above.


Can my 2.25" exhaust really be the culprit by that much, or am i just expecting too much by all this "instant boost" talk?

Think about it, on my ancient t25 I get boost onset by 2500rpm by 3000 I get 10psi flat to redline on a begi S downpipe and a enthuza catback(stock cat in place).
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Old 07-15-2008, 04:55 PM   #14
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Quote:
Originally Posted by JasonC SSB
Got some proper spoolup datalogs done, with some numbers with the AVO. 2nd gear, flooring it at 1500 rpm, same flat road, ambient within 6C of each other. Full boost is 170 kPa.

Remember this is 2nd gear, it takes all of ~4sec to go from 2000 to 6000 RPM

RPM AVOkpa BEGIkpa
2000 117 112
2500 136 128
3000 161 145
3277 170 159
3450 175 170

Huge difference around 3000 rpm - 2psi - this is why the car feels much soggier shifting at 3000 rpm. On a bad day the AVO never felt this laggy. :(

How fast JasonC SSB spools in PSI on a 2254 and a AVO and BEGi manifold:

Code:
RPM	AVO	BEGi
2000	2.4	1.7
2500	5.1	4.0
3000	8.7	6.4
3277	10.0	8.4
3450	10.7	10.0

like i said, sounds like you are on par....


but just to **** you off, with my T3, I see:

Code:
	BOOOOOST in PSI
RPM	Before Screw	After Screw
2700	3		1
3100	6		4
3750	11.5		9
4000	12.5		11
4500	12.5		11.5
6500	12.5		12
7000	12.5		12.5
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Old 07-15-2008, 05:05 PM   #15
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Jason's pulls were done in 2nd gear, mine is in 4th. There is a drastic difference in spool between 2nd and 4th.
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Old 07-15-2008, 05:06 PM   #16
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Quote:
Originally Posted by compuatic View Post
Jason's pulls were done in 2nd gear, mine is in 4th. There is a drastic difference in spool between 2nd and 4th.

ah yes, should be faster in 4th...mine were third
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Old 07-15-2008, 05:11 PM   #17
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Way to rub it in... Mine hasn't been chewing screws though
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Old 07-15-2008, 05:33 PM   #18
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was just looking over my datalogs from our last dyno day in may...

Code:
     |--boost-(psi)---|
RPM   VVT Adv  VVT Ret
2450	1.0     1.0
3000	3.0     2.8
3250	5.0     3.4
3550	7.5     4.7
3750	9.5     6.6
4150    9.5     9.5
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Old 07-15-2008, 06:59 PM   #19
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I think I'm gonna have to go log a 4th gear pull in both the Machine and DD and post the results. Just gotta talk the girlfriend into it now. BRB.
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Old 07-15-2008, 08:29 PM   #20
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Well I got the approval from the GF but only took the Machine out. Takes me 20 mins to get to a highway where I can do this sort of **** in that car.

Anyway here is how fast Paul spools with his 2560. It's about 80F out when I did this. 4th gear.

100% tp @ 1850rpm

2000rpm 2.0psi
2200rpm 4.0
2500rpm 5.0
2700rpm 6.5
3000rpm 10.4
3200rpm 14.0
3500rpm 14.2
**********Obviously from here on up and can put the boost where ever i want it. i want it at 14. Boost duty cycle at 3300rpm is 61 and goes lower from there out to redline to maintain 14.

I think I need to look into an adjustable wastegate actuator or just a stronger one.
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