I'm having my intake manifold and exhaust manifold ported next week. Should I port my stock evo 9 turbo as well? How much of a realistic gain? My motor is stock, no cams, just all the bolt ons , going speed density and bigger injectors.

Should I port it or not.. ?

 

You would make bigger gains upgrading cams than porting all of those components combined.

 

if ur power goal is evenatualy more than 400whp then I would suggest saving your money and eventualy upgrade the turbo.

 

Every little bit helps.

 

Same theory can be applied by buying a bigger turbo which will yield more power than the cams but I don't want to skip some of the important steps which when all done and set will yield big gains. I eventually will be doing cams and bigger turbo but for now i'm interested in gaining the most power out of the stock items.
Curt Brown will be porting my intake manifold and will be adding a 70mm throttle body, ported exhaust manifold , Map O2 and switching to speed density. I was just wondering if porting the turbo as well will be beneficial.

 

Would porting the exhaust manifold cause more turbo lag?

 

If Curt is already porting all of them, have him port your hotside as well. Like someone else said, every little bit helps. Helping the motor breath easier is never a bad thing. It seems like you plan on sticking with the stock turbo for a bit anyway. And if you upgrade to a larger stock frame turbo you could easily swap your ported hotside onto it.

 

Ask Curt Brown--- I feel sure he would have an opinion. However, I would ask you to look at the rest of your intake track, mainly the top pipe to the TB--what size is it 2.5"? Does the pipe neck down to a reducing coupler? if so then porting the TB and manifold wont do much except move the restriction to the pipe I just mentioned. Hence everything after that wont truly benefit from the port. The Ex Man and 02--great places to port with proven gains. Turbo-- not sure but other stock frame turbos gain from porting so I feel sure you would pick up something, just going to depend on how much the porting will cost on the turbo in relation to the HP gained. Good Luck.

 

so where did you come up with this? The 2.5 size piping is more then adequate, especially on a stock turbo.

 

Never said it wasnt adequate--
But increasing the size of the TB will yield no gains if the pipe feeding it is smaller then the TB. The restriction is the smaller pipe. The money is better spent elsewhere.
I think the VIII has a 2.5 inched intake pipe to TB and thats a 63.5mm diameter, so why go to a 70mm TB when the pipe feeding it cant feed it other then to reduce velocity--which isnt beneficial to performance.

 

I don't agree with your theory. I have tried it myself, thinking I would gain some hp from changing my 2.5 inch piping to 3" as my throttle body was 3". There was no gain in HP from doing this.

 

It all depends on your end goal or at least the next couple years. Unless you plan on keeping a stock frame setup I'd say skip it. No sense on wasting $ on a few HP if its of no use down the road. If you do plan on keeping a stock frame send it to Swaintech for some white lightning too. Good luck.

 

First, Thank you for a civil discussion.

Here is what I am getting at...this is all a matter of air velocity/speed. In the OP's example he has two tubes of different diameters. One is the TB , the other a smaller intake tube. Lets use a hose and water since we can see it. If we take the smaller hose and run water thru it, the hose flows as much as it can and it comes out in a steady stream. Now if we add the larger hose to the smaller hose and run water thru the smaller hose the velocity of the water decreases as it hits the larger hose. Air functions much the same way. IE porting will likely be of little benefit to the OP since he will be decreasing the air velocity created by the 2.5" intake by porting the TB.

You are also correct in what you said about the adding a larger intake tube--- Using the OP's TB example. What I was saying is, to get the max air flow(volume) with a ported TB he would need to add a like sized intake. However, as you pointed out making the intake bigger didnt provide more HP-- The reason it didnt make more HP is because the larger diameter tube decreased air velocity thru the TB. So while you are capable of moving more air (volume) you are lacking the velocity (speed) of air to drive up the HP numbers.

Maximizing velocity of air at all points (since this is what we are discussing) is the best way to build efficiency and power. Go too big and flow decreases--as you saw by going 3" on the intake. The op would see the same by adding a larger TB--, little to no gains. I was saying If he wanted to see gains by adding a ported TB then he would need to also add a bigger intake tube. But, that creates another problem as you pointed out--- lack of air velocity. The question then becomes how does he increase velocity again to compensate for the larger intake? He could add displacement, cams, turbo etc.

There are a lot of moving parts to this and a lot of considerations and the conversation could go on as variables change. Most of the time we see these changes on a dyno as moving the HP curve to the rt. Changes in one area have effects on other areas--nothing is simple.

Thank you for the exchange. We are saying the same thing.

 

Curt brown recommends porting the turbine housing as well when porting the exhaust manifold.

Strait from Curt's web site:
" If you have your exhaust manifold ported by me it will be matched to the factory gasket(turbo side) therefore your turbine housing must also be gasket matched to prevent reversion!"

 

Bringing back an little older thread, what if you have a ported turbo, and FP Race Manifold. Or as I try to visualize it, if the manifold is ported to the gasket and turbine housing is not, that creates little walls the air will bounce off of off the non ported housing. So if the manifold is not ported, but the turbo is its just a little more room for air to fill but wont have "reversion"? I've tried searching for this specific with no luck. Thanks much! Nevermind, the FP Mani is pretty close to the gasket already, and I don't believe I will have any problems.

Chris