Yellow Bullet Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
245 Posts
Discussion Starter · #1 ·
Hi all,

I know this is mostly V8's with twins or big singles, and plenty of room for Tial 60 wastegates and the like. However, I have a BMW turbo car with a single PT76GTS turbo on a 6 cylinder. My turbo manifold comes together 6 into 1 with my Tial 44 coming off of the collector. I had a 2.9 psi spring in the gate to see how little boost I could run - it'd creep up to 12 psi or so. It was very slow to spool since the 2.9 psi spring would open so soon and was in fact venting exhaust (to atmosphere), but the thing would still creep! So, I went and put a 9 psi spring in and a Precision T&E 46mm wastegate, and it creeps to 17-19 psi.

So, I think the issue is wastegate placement, but I have few options at this point since it's already fabricated.

I have a few ideas, but not sure if it'll work. First off - I am ok with 17-19 PSI, I just wish I could hit that boost with a 16 - 19 spring so that the turbo would spool as fast as possible. I don't really have enough room to add a 2nd wastegate in this car.



I want to avoid more fabrication since I have to pull the head to get this manifold off, but if I have to, I have to. I could either weld a second wastegate runner off between the head and the collector. It would be super tight, but, it would probably work. I could do it on the middle of the collector between the head and manifold.

Or, instead of running a 2nd wastegate, I could run a pipe from the same location as mentioned above, but tie it into the tube that the wastegate is coming off of. So, it'd allow the manifold to dump exhaust from more places on the collector while still using 1 wastegate.

Finally, I could use my manual boost controller and try raising the boost controller up to 15 psi or so. Its a ball/spring type boost controller which is supposed to block pressure to the wastegate until the desired level is achieved - so, maybe if I block pressure to the wastegate right up to 15 psi, it'll pop open at 16 and won't creep any. I don't have much faith in this option.

What do you guys think?

Thanks!
 

·
:D
Joined
·
1,427 Posts
wastegate placement is definitely your issue.
I dont know if fabricating a manifold that requires you to take the head off, just to remove the manifold is smart idea either.

Why not just start over and build this the right way? If not, I'd add a second gate on the other side of the collector.

just my .02
 

·
Registered
Joined
·
245 Posts
Discussion Starter · #3 ·
wastegate placement is definitely your issue.
I dont know if fabricating a manifold that requires you to take the head off, just to remove the manifold is smart idea either.

Why not just start over and build this the right way? If not, I'd add a second gate on the other side of the collector.

just my .02
Definitely not interested in starting over, the car is done!



The manifold doesn't need to be removed with the head, but it's so much easier. There's 24 nut/studs on that thing and they're not easily accessible, even with stock manifolds.

I am going to try and tie in a 2nd pipe using 1 WG. I will tie in from the side between the head and the collector into the 1 wastegate tube already there.
 

·
Registered
Joined
·
1,592 Posts
Yeah, with that setup the exhaust gasses from at least 4 of the 6 runners won't want to make the turn, and it's not ideal for the left two either. Best bet is another WG off the right side of the collector to balance it out.

Another option in really tight top mounted setups is to put the wastegate on the turbine housing. It's very efficient since the exhaust gasses don't have to change direction, you'll maximize the flow of the gate. In this configuration a single 44 would probably do what you want, but you could add it as a second. ATP turbo sells V44 block of caps so you won't have to pull the head to make this happen, but the downside is that you will have to modify your turbine housing which you'll probably have to replace if you plan to sell the turbo someday.

Here's a pic of what I'm talking about, and where I got the idea: http://www.eagletalon.net/pics//Red%20Car%202006/040306%20-%20Wastegate/IMG_1002.JPG
Full page with more pics: http://www.eagletalon.net/pics/?d=/Red Car 2006/040306 - Wastegate

Edit, that pic wasn't there when I started this reply. You probably don't have room for this, but it may be worth a look.
 

·
Registered
Joined
·
245 Posts
Discussion Starter · #5 ·
Thanks Kjewer1 - I had looked at that. The only problem was that a lot of people were telling me that it would eventually crack since it'd be stainless to cast iron in my case. I can't add a wastegate to the opposite side because of spacing and oil drain, but I can add one on either side of the long side of my collector.
 

·
Registered
Joined
·
284 Posts
Remember boost creep is a function of restriction . The cars i had problems with where all stock heads and cams with a mild upgrade in turbo size the ussual cure was port the heads or swap the cam since we are all after more power ,the boost creep was cured . The wastegate placement and the short runners arent helping have you tryed a wastegate with a reverse dome valve it might help .
 

·
Registered
Joined
·
38 Posts
have you got any pics of the mani off the car? it looks to me like the wg tube is at over 90deg to the flow. if you could angle it more in line with the flow you would see benefits; even if it then reversed direction with a bend. also you could try porting/smoothing the upstream side of the wg takeoff and leave the downstream edge nice and sharp. or even weld on a tiny divertor plate on the collector. either way i think it has to come off again.

I think all you will get with one of those boost devices is more boost with the same amount of creep. they are no-where near as good as some people make out. its just a ball and spring.
 
1 - 8 of 8 Posts
Top