Boost taper
May 15, 2006, 04:15 PM
#1
Boost taper
Well I have had enough with my boost taper problems.
Magnus Intake Manifold, Stock Throttle Body, 2.5" upper IC pipe, Buschur "Deluxe IC", 2 1/4" lower IC pipe, GT35r (E-Cover, .63 AR hotside), Hallman MBC (Hooked up to the Manifold). The exhaust is a 3' long pipe exiting the front bumper (No muffler obviously), Tial 44mm WG (externally gated), Shearer tube manifold.
Tell me why my car drops 5psi (34 -> 29).
Its not the exhaust obviously. Its not the turbo itself obviously. Obviously not the intake manifold, the boost controller, upper IC pipe, etc....
The only thing I cant think of that is left is the IC itself may not be able to flow it. Anyone have the Buschur deluxe IC with a bigger turbo trying to run high boost? The IC isnt exactly small but its the only thing I can think of that it might be.
Magnus Intake Manifold, Stock Throttle Body, 2.5" upper IC pipe, Buschur "Deluxe IC", 2 1/4" lower IC pipe, GT35r (E-Cover, .63 AR hotside), Hallman MBC (Hooked up to the Manifold). The exhaust is a 3' long pipe exiting the front bumper (No muffler obviously), Tial 44mm WG (externally gated), Shearer tube manifold.
Tell me why my car drops 5psi (34 -> 29).
Its not the exhaust obviously. Its not the turbo itself obviously. Obviously not the intake manifold, the boost controller, upper IC pipe, etc....
The only thing I cant think of that is left is the IC itself may not be able to flow it. Anyone have the Buschur deluxe IC with a bigger turbo trying to run high boost? The IC isnt exactly small but its the only thing I can think of that it might be.
May 15, 2006, 08:28 PM
#4
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So you did a leak test? The cheap and easy thing to do would be to break out the black zip ties. At what rpm does the taper begin? And what are you spinning the motor too?
May 16, 2006, 12:15 AM
#5
Yes I pressure tested the intake system. It has a few leaks on some of the couplers. They are T-Bolted tight enough where they are squishing the pipe. Im gonna use some hairspray and try to seal them up but I dont see how those would cause a 5 psi drop.
Ill spin it to 8.5k under load and 9k between shifts (If shifting NLTS). I hit peak boost at around 5k and it starts the taper at 6k. The taper stops at about 7k and holds that boost until I let off.
Ill spin it to 8.5k under load and 9k between shifts (If shifting NLTS). I hit peak boost at around 5k and it starts the taper at 6k. The taper stops at about 7k and holds that boost until I let off.
May 16, 2006, 12:26 AM
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Originally Posted by TrinaBabe
Tell me why my car drops 5psi (34 -> 29).
1) u are using the wrong spring combo in the WG (2 stiff or what i think which is not stiff enuff)
2) u maxed out the flow of the Magnus intake manifold nicknamed "reynolds wrap" for it's inability to hold anything over 40PSI reliably.
3) u maxed out the flow of your 35R due to it's .63 A/R. with the amt of mods listed & your high shift point, the .82 A/R would have been the optimal choice.
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May 16, 2006, 12:22 PM
#8
The tial has a 1.3 bar spring rate in it.
The lowest boost is about 21psi. Its not the tial.
The Magnus intake manifold will flow enough at 35psi to hold it. We have used the same intake manifold on more than just my car and it holds perfectly fine.
And yes, the better size hotside would be the .82 but I didnt get that. That doesnt change the fact that tons and tons of people use the same hotside and thier boost holds perfectly fine. People have been using SC-61s for a long long time with the same hotside and same compressor housing and can hold 35psi all day long.
Now you guys are starting to see the reason Im getting frustrated
The lowest boost is about 21psi. Its not the tial.
The Magnus intake manifold will flow enough at 35psi to hold it. We have used the same intake manifold on more than just my car and it holds perfectly fine.
And yes, the better size hotside would be the .82 but I didnt get that. That doesnt change the fact that tons and tons of people use the same hotside and thier boost holds perfectly fine. People have been using SC-61s for a long long time with the same hotside and same compressor housing and can hold 35psi all day long.
Now you guys are starting to see the reason Im getting frustrated
May 17, 2006, 03:06 AM
#11
Originally Posted by TrinaBabe
The tial has a 1.3 bar spring rate in it.
The lowest boost is about 21psi. Its not the tial.
The Magnus intake manifold will flow enough at 35psi to hold it. We have used the same intake manifold on more than just my car and it holds perfectly fine.
And yes, the better size hotside would be the .82 but I didnt get that. That doesnt change the fact that tons and tons of people use the same hotside and thier boost holds perfectly fine. People have been using SC-61s for a long long time with the same hotside and same compressor housing and can hold 35psi all day long.
Now you guys are starting to see the reason Im getting frustrated
The lowest boost is about 21psi. Its not the tial.
The Magnus intake manifold will flow enough at 35psi to hold it. We have used the same intake manifold on more than just my car and it holds perfectly fine.
And yes, the better size hotside would be the .82 but I didnt get that. That doesnt change the fact that tons and tons of people use the same hotside and thier boost holds perfectly fine. People have been using SC-61s for a long long time with the same hotside and same compressor housing and can hold 35psi all day long.
Now you guys are starting to see the reason Im getting frustrated
Any wastegate system, but espesially those with a large surface area have a max boost rating of aprox 1.3 to 1.7 times the spring pressure in the wastegate depending on the surface area of the wastegate, and how restrictive the AR of the turbo's exhaust housing is. This is because the exhaust pressure in the exhaust manifold is helping to push the wastegate open.... the larger the wastegate surface area the more effect exhaust pressure in the manifold has on this. So, looks like your max boost is around 1.38 times the spring pressure with your setup. It is higher than that at lower RPM's until exhaust pressure builds up in the exhaust manifold forcing the wastegate open.... so you have tapper.
With your setup if you want to be able to HOLD 35 psi you will need a 25 psi spring in your tial, that would be 1.8 bar. Heaviest I can find is 23.2 psi (1.6 bar) that with your setup should allow you to sustain 32 psi to redline with a minimum boost setting of 23 psi.
If you want more than 32 psi you will need to go to a more free flowing exhaust housing on your turbo (.82 AR vs .63 AR) or go to a smaller wastegate surface area (40 mm vs 44 mm).
I had the oposite problem with my car when trying to run low boost I get some boost creep upwards and was thinking about switching to the 44 mm wastegate. Seeing your issues I am almost glad to have the 40 mm now with the smaller surface area on the wategate I should be able to run more boost on the same setup.
Keith
May 17, 2006, 10:16 AM
#12
Well on our DSM we had a Tial 44, 1.3 bar spring and an FP3052. It could hit and hold 30psi easily till 8.8k. Technically it would taper about 2 psi but that is ok with me... its this 5psi thing that is making me grumpy
Another side note, even if I run it at 23 psi it will taper down to about 20. It doesnt ever seem to hold a boost steady
Another side note, even if I run it at 23 psi it will taper down to about 20. It doesnt ever seem to hold a boost steady
May 17, 2006, 12:00 PM
#13
Our setups are virtually identical, the only difference being you have a 44 mm tial and I have a 40 mm tial. You have boost taper, I have boost creep if I run less than 20 psi. When the only difference between two setups is the wastgate being used, and one of them gets minor creep while the other gets major taper.... draw your own conclusion What was the A/R of the exhaust side on that FP 3052 on your DSM setup?
Try using a large blue / small blue spring combo in your current Tial and see if that helps.
Keith
What was the A/R of the exhaust side on that FP 3052 on your DSM setup? Try using a large blue / small blue spring combo in your current Tial and see if that helps.
Keith
May 17, 2006, 01:59 PM
#14
Hey Trina
What springs are you currently using in your 44mm Tial for the 1.3 bar pressure? From the Tial web site PDF file on springs for the 44mm there are two different combinations that would give you 1.3 bar. A large green spring with a small blue would give you 1.3 bar and a large blue with a small green would give you 1.3 bar.
If have the large green with small blue combo and want to try the large blue small blue combo for 1.4 bar I have a spare large blue spring that I would sell to you cheap ($20 shipped)... it is just taking up space on my shelf.
If on the other hand you have the large blue small green combo and end up buying a small blue spring to replace your small green spring I would be interested in buying your old small green spring to use in my Tial. Here is a web site where you can buy indevidial Tial springs to suit your needs: http://www.atpturbo.com/Merchant2/me...egory_Code=WGT
Half way down that page they have links for Large springs and Small springs. They are $30 each plus shipping.
Later,
Keith
What springs are you currently using in your 44mm Tial for the 1.3 bar pressure? From the Tial web site PDF file on springs for the 44mm there are two different combinations that would give you 1.3 bar. A large green spring with a small blue would give you 1.3 bar and a large blue with a small green would give you 1.3 bar.
If have the large green with small blue combo and want to try the large blue small blue combo for 1.4 bar I have a spare large blue spring that I would sell to you cheap ($20 shipped)... it is just taking up space on my shelf.
If on the other hand you have the large blue small green combo and end up buying a small blue spring to replace your small green spring I would be interested in buying your old small green spring to use in my Tial. Here is a web site where you can buy indevidial Tial springs to suit your needs: http://www.atpturbo.com/Merchant2/me...egory_Code=WGT
Half way down that page they have links for Large springs and Small springs. They are $30 each plus shipping.
Later,
Keith
May 17, 2006, 02:09 PM
#15
I have a whole bunch of different springs if I want. This combo is the biggest I can get away with if I still want to floor it on pump gas... I dont really care anymore about pump anyways so I may just make it tighter. I dunno. If you want another spring I could find my stash and probably send ya what ya need.