samc

i've started partially siamesing and porting my superram, and it seems like there is a lot of metal to remove. and all i'm doing so far is trying to match the gaskets that came with it...

is ths typical? or am i just going overboard.

another question: when i install it, do you think i'll have to pull the TPiS big mouth manifold and port it too? it is currently matched to the ASM large tubes.

thanks,
sam

Monty

I ported my SR when I still had it, and it seemed to help. I didn't siamese the adjacent runners though. However, I saw a good post on another message board awhile back, and the guy did a pretty good test of a non-siamesed SR, and then tested it again after he siamesed the runners about 1" down. From what I recall, there were minor differences in power at lower rpms, but as rpms increased, the siamesed ported SR made more power. I think the max difference was about 10hp. Not a huge difference, but certainly worth doing.

I think the post was on one of the Camaro/F-body forums.

Just be careful, as you know the runner walls are pretty thin.

samc

thanks, monty, but what i'm confused about is you're saying the runner walls are thin - mine seem to be very thick in most places. like i can remove a lot of metal just to match the gaskets that came with it. strange.

Monty

I meant the outer portion of the runner walls, the side that faces the valve covers, especially where it bends.

ralph

Sam, be careful with the siamesing. I cut about 2 1/2 inches outa mine at the beginning of the season and it killed it. I was running close to 3 tenths off. Had them rewelded and i was back to my normal times. I did a ton of reasearch before i cut them and on paper it looked good (about 10HP, loose a little low end torque), but in reality it killed it everywhere. Even SOTP in the street it felt like it lost a lot of low end. Maybe i could tuned into it, but i wasn't up to it and gave up. My conclusion was that siamesing the runners wasn't exactly the same as shortening them and that the reverse pressure waves were creating turbulance between adjacent runners. Maybe you'll have better luck, but it absolutely didn't work for me.

as far as porting, mine had a real bad mismatch between the runner and the base on the drives side (was shifted about 3/16in). I've about cleaned that up but it left me with almost no material between the adjacent runners. You'll want to port the base as well. From what i've read, the base is more restrictive than the runners, so doing only the runners wont buy you much. I pretty much tried to open the runners and as much of the base as possible to 1 3/4 inch dia (more at the top of the runner). If you try to go larger, you start to run out of material where the base and runners meet unless you reshape it a bit and take more material outa the top. I also started to run outa material where the base meets the head. I opened it to match a 1205 gasket, but fell short of material on the top and bottom. some have been able to open it to a 1206, but i don't know how (at least not without doing some welding). Good luck!!!

GlennS87

My builder had to do a decent amount of porting to match my superram up to my TPIS Big mouth. It would have been pretty bad not doing anything.

samc

thanks for all the tips! i think i have one runner just about done, and i understand now what you mean. one end is fairly thick walled, while the other end is thin in places and thick in others, like where the tubes touch. i'm only siameseing about 2" down on the top, and am now wondering if i should leave the wall in between the two cylinders that fire consecutively (5 and 7 i think??). but i am removing so little i think it won't make a big difference. i'm definitely taking my time and checking the wall thickness very frequently!

I'll check the big mouth when i pull the old runners, maybe buy some gaskets before hand, and if it looks bad (i'm assuming it will) i'll pull the base and do some more porting.