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Thread: Wastegate size?

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Posts: 31-37 of 37
2010-07-25 04:53:06
#31
big turbo big boost small gate
big turbo small boost big gate


less boost you run the more control you need,
2010-07-25 05:01:42
#32
With less boost, there is less exhaust gas. Right? Less exhaust gas means less exhaust going through the turbo, thus, less going through the gate.

I had a wastegate open (just one) on my TS setup. It opened up to just about 1/16". The car failed to make boost at all until over 6000rpm. Actually helped traction a bit. I would like to see someone put a vacuum on their wastegate to lock it open, then see if they get any boost at all. I don't think it would see more than 1-2psi of boost.

Another perfect example is my old disco potato car. Would run 6psi all day long without any creep. Once I started pushing over 18psi I would get creep up to 21-22psi before boost would taper. So how would you explain creep under high boost, as opposed to low boost?

It is pointless to go with a larger gate unless you have a very large turbo running low-mid boost levels under 18psi. By large, I mean 500whp+. The rest comes from wastegate placement.

Running a 38mm wg on a T25 on 3psi. Very little exhaust gas will be exiting the manifold compared to a GT35r on 3psi. So its the total volume of air you wanna look at. Not necessarily the boost level.
2010-07-25 05:03:10
#33
Originally Posted by Forced
big turbo big boost small gate
big turbo small boost big gate


less boost you run the more control you need,


Exactly what I'm saying, in a nutshell.
2010-07-25 05:17:12
#34
Originally Posted by ashtonsser
with my 60 trim T3 with the .82 turbine housing and tubular manifold i was running, i would have nasty boost creep with running my Tial 38mm, It had a 1bar spring in it but with the boost controller off it would hit 19-20psi by redline no matter what i did. It will sit at 14.7psi till about 6500 or so then rise slowly to 20psi by redline. It was a simple matter of that it was too small for the turbo i was running and the boost and power levels i was running.

Thats why with this 6765 that im gonna run i went to a 50mm Synapse wastegate. Ill probably adjust it to hit 18-19psi. It has full adjustment which is a really nice thing so your not having to swap out springs. Then use my electronic boost controller to go to 30-35psi maybe more. But you should have your spring set to the lowest psi you want to run.


Do you have any pics inside of the manifold?

One important factor many forget is wastegate placement.





When looking inside of manifold where the runners meet, the "point" that is created at the collector must sit below the wastegate outlet. This is one of the main causes of creep on ram-horn and poorly designed tubular manifolds.

I have run your turbo on many application with a 38mm gate with no issues.
2010-07-25 05:22:30
#35
yeah the mani i was using wasnt the greatest. It was a cheapy rwd tubular t3/t4 mani that i just rewelded to keep from cracking. Wastegate placement wasnt bad but not the greatest. It sat at a 90 deg angle from the collector so it wasnt as smooth as the one you pictured. When i get my DIY manifold kit from Mazworx here next week im gonna start putting a mani together and the wastegate pipe is gonna flow in almost the same direction as the collector so that its a nice smooth transition. Should work flawlessly.
2010-07-25 05:31:51
#36
Originally Posted by ashtonsser
yeah with two, i would highly doubt that you have any creepin going on. As for the boost levels. Never went anything lower than the 1 bar spring pressure which again in the end would make 19-20psi by redline. It would be worse at lower levels as to run lower boost levels you would need to allow more exhaust gas through the wastegate to keep the levels down. So if it was doing that at 1bar and seeing 5-6psi of creep i would imagine lower levels would be worse.


I still fail to see how you got creep so bad on a mid-large frame turbo. I ran a 10psi spring to start in my first GT30r setup .63 on a log manifold with crap wastegate placement and still never got any creep.

Anyone have any other experience with creep they can share. This is a good conversation.
2010-07-25 06:27:20
#37
Not sure, probably wastegate placement or something. I didnt have the best setup manifold out there. haha

But hey it worked for what i needed it to do. And i didnt mind it hitting 20psi on pump gas. I had no issues with it. It wouldnt spike or anything like that so i just didnt worry about it. No on higher boost levels i wouldnt have any creeping at all. Just the lower boost level. You can hear the difference in the turbo spool and wastegate sound at each boost level. You can bigtime hear the gate open at wastegate pressure but at 30psi you would hardly hear any sound from the wastegate and all turbo spool.

Im sure you have heard this difference on your car. The higher boost level the more just absolute turbo spool sound there is. The gate kept up fine at 30psi. Never an issue.
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