Porting a FP Race Manifold to 7cm?

[fergulus]

I just purchased a FP Race Manifold, and saw that the manifold to turbo is only 6cm. I have a frank 20g, and was going to be porting the turbo to 7cm to help with spoolup. Should I go ahead and port the turbo, and not worry about the variation, or should I wallow the collector area out to match the 7cm that the turbo will be?

 

[crimsondragon]

I'm pretty sure the FP manifold has a 7cm opening. Mine did when I received it back in the group buy.

 

[e85_4g63]

So your saying the manifold or the turbo is a 6cm2?

 

[Deepnine]

Turbo and Manifold should be ported to match each other.

 

[fergulus]

As you can see, the Manfold-Turbo outlet on the manifold is 2 3/8" (2.375") or 6cm. There is no squared, because this is a measure of the diameter, not area. The MHI turbos have the ability for a 7cm flange, which I have, as well as a 7cm ported manifold.

This would mean that I would have to do a 1cm port, which is pretty significant.

 

[pboglio]

A 7 cm^2 factory MHI turbo gasket is 2.390" in diameter. Why do you want to port the FP manifold collector bigger? There is no gain from doing it. Just match port the turbine housing to the collector diameter and it'll be good to go.

You guys do know that 6 cm^2 and 7cm^2 represents the volute area, not the collector area.

 

[fergulus]

The MHI turbos have that lip on them, to use the mitsu flange to line the turbo to the manifold. People port that lip away, and you increase the diameter by a good portion. When I port the exhaust side of the turbo, I will be increasing the diameter to larger than 6cm. I put on an aftermarket manifold a few months ago, and was able to see the difference in gasket sizes required. The mitsu gasket was the 2.39", and with the turbo ported just to take that lip away, a larger gasket is required. I wish I had taken pictures to illustrate this, but hindsight is always 20/20

 

[gorf]

gasket match porting - take your gasket lay it on the manifold and mark anything that sticks out with a magic marker - do the same on the turbo. if either need porting just remove the magic marker.

 

[romeen]

As pboglio mentioned, the 7cm^2 turbine housing refers to an area, not the diameter of the turbine inlet. It can be confusing for some because many guys refer to it simply as a 7cm housing (w/out the squared part) which can be confused for the diameter of the inlet.

The 7cm^2 turbine housing has a 60mm inlet diameter when the step is removed so your manifold is fine as is.

 

[pboglio]

The MHI turbos have that lip on them, to use the mitsu flange to line the turbo to the manifold. People port that lip away, and you increase the diameter by a good portion. When I port the exhaust side of the turbo, I will be increasing the diameter to larger than 6cm. I put on an aftermarket manifold a few months ago, and was able to see the difference in gasket sizes required. The mitsu gasket was the 2.39", and with the turbo ported just to take that lip away, a larger gasket is required. I wish I had taken pictures to illustrate this, but hindsight is always 20/20

Yes, people port the lip away but not by opening up the machined counterbore diameter for a 7cm2 housing. If it was the smaller 6cm2 housing then yes I typically port everything up to 2.36" diameter. On the 7cm2 housings I don't open up the diameter further as it isn't needed and forces you to use a crappy aftermarket turbo/manifold gasket.

Just touch the grinder to the step and remove it leaving the machine counterbore completely alone, untouched. This way the factory 7cm2 MHI gasket will work perfectly.

It looks like you opened up this machined counterbore diameter, and now I can see why neither the MHI 7cm2 gasket will work or the FP manifold without porting.

 

[fergulus]

Y
It looks like you opened up this machined counterbore diameter, and now I can see why neither the MHI 7cm2 gasket will work or the FP manifold without porting.

I havent ported anything yet, that picture is of the collector of the FP manifold. That shows that it is 2.37" in diameter, which you all say is the correct diameter for the MHI gasket. I guess I just misjudged the size, because it looks significantly smaller than what I remember on the other manifold.

As far as porting the turbo, I do know to just remove the lip, I didn't mean to imply that I was going to further bore the turbo. This is going to save me alot of time then, just having to worry about boring the turbo, and not the manifold as well!