Does anybody know if somewhere down the years, SLP changed the design of theier siamesed runners? I saw some pictures of the early runners and saw that one pair of tubes one either side was siamesed all the way down while the other pair was only siamesed in about a half inch. I got my runners new from Summit during their clearance sale and they're only siamesed about 1.5 inches in. Can anybody shed any light on this? Which would be the better design?

 

Not sure if it was SLP but some one DID make semi-siamesed runners a while back. Thta's probably what you saw.

 

AS&M made and I hear still makes the siamesed runners.

They look like regular runners on one half, and smooth casting on the other.

 

Aren't AS&M & TPIS's old siamesed runners made from their tubular runners though?

The SLP ones are cast aluminum.

 

Let me be the first to tell you that you're not crazy. What you see in the picture that jegs/summit always showed for them is what you describe, where one pair is fully siamesed for the whole length and the other side is barely siamesed at the top. Even though i'd venture that most people have never seen a set like that, it is the original design.
I think the reason it was changed is also the reason that the second design is probably the better one. Ideally you want all of the runner lengths/paths to be as consistent as possible. Building in a 4" difference in length on purpose is not conducive to consistent fueling, especially in a port injected engine,
Not that there is necessarily anything wrong with siamesing the whole runner length, just that you'd want it to be consistent for all the pairs. And since it takes a lot of work to completely open a runner up like that, you're pretty much better off starting with the later designs anyway unless you plan on majorly reworking things.

 

Great info! I was wondering that myself!! Later!

 

I have a original set of those runners......never used. But they have 2 large windows cut in the rear runners. They will be fully siamesed when finished. Should I cc them for volume? or is this critical? Thanks