Did some porting on my rear manifold

[AWeb80]

a stock 94 3100.....

Figured I'd port it good while it's off the motor.










OK, got the rear mani ported and ready to go.

Here is the entrance toe the rear mani from the X-over.

Nasty looking.........








I opened it up a bit.... :high5:




















Here is teh DP side of the manifold....


a reminder how NASTY and small it was........





DONE!!!!!

I spent lots of time here. I forgot to measure what it was.....but I bet I took out nearly a 1/4"...
















finally, the ports them selves....

They all looked pretty much the same.









I didn't open them much, as they are not too bad already, I just smoothed everything out and opened it up down stream as much as possible..

[1QUICKHATCH]

Looks good! You have too much time on your hands!lol! Should have upgraded to the 3400 manifolds then did the porting.

[IsaacHayes]

Yeah 3400 ones are much better, but then you'd need a new flange for the DP and a flex tube installed.

Uhm, your 3100 manifolds look way better stock than mine......... No way I could port mine as I felt it and where it is restricted inside, the outside actually kinks down to that area, so if I ported out the restriction it would just go right through the side wall of the downpipe area....

Does your downpipe exit on the side of the manifold or center? Mine is in the center.

See the restriction there, I can't port that out or it goes through the wall....


But my Downpipe flange was opened up to 2" (past what knocking the inner pipe out gets you).

Pipe is 2.5" stainless mandrel bent.

[AWeb80]

mine is the side exit one.

I thought about getting the center exit manifold, but didn't feel like rebuilding a 2.5" DP when I already have a 2.5" that works great.

[IsaacHayes]

Well as you can see your side exit one outflows mine stock for stock so I'd say you're doing pretty good. The 3400 one has short runners for the rear head, that's the only main advantage. Unless you get a 2005+ 3400 one then you get the HUGE ports that match up to 3500 stuff.

Not only does my center one have a smaller outlet, but how it flows is not as good as your side exit. Your side exit is almost like a Y pipe, where mine you have the front bank going into the back log before it can exit. So mine has more interference and turbulence I'm sure.

[AWeb80]

Here is my manifold.

Does anyone have a stock one laying around? I'd like to get the inlet and outlet measurements to see how much I really took out....

[AWeb80]

FYI, I had a 1-3/4" hole saw laying around and i wanted to see if it would fit because it wasn't close when i started. it fell right through the inlet and outlet with no problem so that made me happy.

[torq455]

that sure looks like a lot of hard work for a little gain. nice work though!! hats off to your patients and persistance!

[AWeb80]

Ya. It may not help much, but i couldn't stand putting it back on with it looking like it did.

[IsaacHayes]

http://www.jeepnuts.com/12sGASE/images/3100rearmanifold.jpg

Look at this one, that's how mine is shaped. Looks like someone on that picture ported it where it broke through the manifold then welded on top filling it back in...

[AWeb80]

Ya, that doesn't look like it flows at all.....

[IsaacHayes]

I know It's just too old and a pain to try and remove in the car though.

[1meanz]

what would a coustom cross over do? because that would be the next restriction. what size is it anyway? looks like ALOT smaller then 1 3/4" lol.

[AWeb80]

I'll find out, as I'm in the process of making one.....

I have a custom front manifold made.....

[IsaacHayes]

LOL after all the porting, you make custom.. Just make some shorty headers and call it good