I'm want to fab up a intake mani when my car is done. It's going to be a bridgeported(decent sized bridge) with a GT4202R. I was wondering what you think would be the best sized runners (OD) to go with. This is the size of the plenum I plan on going with.



I'm looking for more mid/top end, but I really don't want to kill all my low end.

Any suggestions?

 

No matter what you will loose response on low end. If you want to keep as much as possible, keep the exhaust ports stock.

 

I'm not really worried about losing low end, I'm just wondering what would be the best size runner to go with, OD wise, for the setup I'm going to be running.

 

The Ross D-plenum along with their velocity stacks and billet runners are very nice stuff.

 

That is exactly what I am using. All of their products. I'm just not sure on the size of the runners I should use(IE 2", 2.25" etc. etc)

 

Same stacks that I have as well. Tom knows his stuff! He's actually the person you should talk with about it as well.

 

I'll give you some free advice. Tom's velocity stacks will not work for our applications... You'll need some custom make components. Ask me how I know

 

Worked on my application... as well as Crisspeed's. I think he's in good hands.

 

........Okay then....How do you know hot shot


-J

 

huh?

 

i smell **** in here...bull **** specifically. hehehe

 

The exhaust ports are being ported. The motor is getting a decent sized bridge. I'm not going to be cutting into the water jacket, but I will probably be notching the rotor housings.

I'm not worried about losing bottom end, i'm going with a large turbo and bridge, bottom end is the last thing I'm worried about lol.

Do you think 2" would be good? I don't want to go too big, and I don't want to go too small.

 

Too much information missing to give a suggestion!
Let's start with which motor?

 

I have had two types of bridgeports. When you "don't" port the exhaust, you get faster spool and a broader power curve. I don't care if you believe me. Im not speaking on what somebody else told me. I speaking of personal experience Ray and I have had with bridgeporting.

 

It's stated in the title! lol. It's a RE

 

Ernie, I'm not arguing Tom's knowledge or science. He's a great guy with great products. I spoke with him over the phone during the winter when I was in the R&D stage of my manifold. His velocity stacks that he has pre-made are too big to roughly match to the factory port diameters.
I don't want to put words in his mouth and say he agreed with me but we did discuss him making me a custom size for a higher cost. Unless your really porting the hell out of your LIM you're going to have to bottle neck the top of the LIM to match. Lets keep it peaceful I'm just sharing my experience I'm not here to compete or fight.

 

I did more than just talking and thinking. I actually built one. https://www.rx7club.com/single-turbo-rx-7s-23/my-custom-upper-intake-manifold-%2A-pictures%2A-771544/
But I appreciate your post

 

I plan on making a complete mani, upper and lower, one piece.

 

beuler?

 

Why not measure the port going into the iron. I would match up to that size. There's nothing worse than something too big as it'll create turbulence.

 

That's exactly what I'm trying to avoid, using something that is too big and will create turbulence, or something too small that will create a restriction.

What are you ideas on tapering? Like start off at port size, taper as it comes up, then increase to port size again a little bit before it goes to the plenum.