FYI to the small block chevy guys... Found these on eBay. They are going to work great for my system. Just need to make a conversion flange. Better buy before he realizes the turbo guys would probably pay a lot more for them..


http://www.ebay.com/itm/200564459918?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648

 

Manifold before flange was attached.
Manifold with home made T4 flange.
Manifold with flange and turbo.

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You should port match the adapter to the turbine flange

 

are you placing the gate on the crossover piping??

 

Yes gate to tap in just below the manifold.

 

Looks like he's planning on twins........

 

I am going to weld a tube in that hole that will protrude into the housing and blend to it. That will keep the velocity up. It will still be larger than the Area of the A/R ratio.

 

Just bought 2 of the manifolds, thanks for the tip!

 

If you are going to a T4 flange there are a couple places making adapters for Grand Nationals that might work. The Grand National in stock form used a 3 bolt flange that is very close to this bolt pattern. It may be exactly the same. The bolt circle on these is 3.125 inches. I'm not sure what the GN bolt circle is, but it is very close. Also, Turbonetics has a GN "Cheetah" series turbo with a .85 A/R that would almost bolt right to this manifold, but the T-series compressor housing would probably hit the valve cover.

 

What about turning them upside down and using the longer side to bolt the turbo to?

 

Spark plug clearance. Rams-horn would get in the way. But, you could do that with "Shorty" headers on a twin turbo. Some of those are right in line with the flange bolts.

 

I'm a little lost. What do you do with the bottom? Your using an external waste gate?

 

The bottom flange becomes an inlet from the opposite bank cossover tube in a single turbo system. If twins are being used, then it can be a connection for the wastegate, or a balance crossover tube similar to that in the single turbo system. In that case, a single wastegate off of that tube could be used to control both turbos.

An internal wastegage turbo can be used too, but in a single turbo system all the exhaust would need to go through the top flange on one side and it is only a 2 inch diameter hole. That might become a choke point at a higher horsepower level. In a twin turbo system, internal wastegates would probably be ok because you would have two 2 inch holes.

You can also plumb the wastegate out of the flange adapter between the turbo and manifold. I started to go this route, but then realized that all the exhaust would need to go through the 2 inch flange, and so I'm going to either tap into the crossover tube below the manifold, or slap it on the upper flange of the opposite manifold (I'm using the same manifold on that side too.)

 

If you hook the external wastegate to the opposite side top flange then wouldn't you have to plumb it into the x-over anyway to get rid of the exhaust?

 

If you are building a turbo system, please post pictures. I'd be very interested in how you set yours up using these manifolds. Thanks.

 

If you were using a twin setup with internal gates I wonder if you would have trouble blocking off the bottom with a plate and just using the top..............

 

I have heard that there should be a balance tube, but I'll bet it would be ok without it. Used to be ok because the heat riser though the intake manifold would do it.

 

what is the bottom hole diameter measurement

 

bottom port is 2 inches- these would be sweet for a 30-40's rod but just tried it on m el camino and dont think it would work

 

Not starting a build anytime soon but my idea is similar to yours. Fab a t4 flange and make a x-over with a wastegate dumping under the car. I will use the valve cover for the oil return location. This aint race car materal but Im thinking it should support 550 maybe 600hp?? not bad for $39.
I wouldnt worry too much about the 2in. manifold flange, the restriction inside the turbine housing is a hell of alot smaller than 2in. as long as the goals are realistic the manifold should work well for a budget build.