Best Wastegate placement is???

[4g63telantra]

I just picked up a new exhauset manifold for my T4 set-up.

The manifold has no flanges for a wastegate. I wanna place my 38mm WG on the manifold but not sure where is the best place to make a flange for it is.

Would it be the 1st runner or chould I run it where all the runners meet?

Any pro's/con's of running one from 1st runner or where they all meet?

 

[JayRolla]

I notice most mani's with the WG flange are on the number one runner. Closest one to timing belt, so that must be the best.

 

[MyBeatGSX]

Best location is where they all meet. There are no cons to this setup, you get the best boost control and keep all cylinders at an even pressure.

The downside of placing it on the #1 runner is that you are now only bypassing 1 cylinder's worth of exhaust. This is bad for boost control and it's bad for the other cylinders. You also end up with horribly unequal backpressure across the cylinders. I would never place a WG anywhere other than the collector.

 

[4g63telantra]

Thanks.

I was thinking of keeping it away from the runners.

A single 38mm maybe to small for a GT40
Its cheapper to get 2x38mm WG then it is to grab a 48mm WG.

How about a 2 WG set up?

 

[JayRolla]

I guess you guys are right, its usuall at the end of the #1 cylinder in the collector.

 

[drivemusicnow]

Okay first thing you have to realize is that the manifold is under pressure. "back pressure" is one way to say it, however figure if you're running 25 lbs of boost, you should be seeing about 18 psi pressure in the exhaust manifold. WHERE you bleed it from the manifold is not all that important. If you mount it off of the first runner, (like the cast manifolds typically are) you're not only allowing exhaust gas from 1 cylinder, you're reducing the pressure inside the manifold. I would agree that off of the collector would be the best option on a sheet metal manifold.


As far as which is better; 2 38mm valves would be approximately approximately 2268 square milimeters of surface area. A single 44mm valve has 1520 square milimeters. That being said, you should be fine with the 44mm V band Tial.

Although there is a "80" mm HKS valve on ebay right now