Whats going on guys. What would happen if I where to have my siamesed SLP Runners "siamesed" down deeper?

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Look for the thread "In search of a better flowing TPI". The Cali guys have pretty much perfected the art of Siamesing the SLP. I know that some of the most extreme mods included cutting it apart and siamesing the runners all the way down. Then siamesing the runners in the base down to within a few inches of the cylinder head. I have not gone the route of siamesing my TPI but have applied other methods for maximizing flow and power from my 355. I'm very pleased with my results but am excited to see what others are doing with theirs.

 

Well I'm flattered to say I'm a "Cali Guy", hahahha. I've read a few things about cutting them in half too. But that's a bit extreme and I'd really hate to destroy the clean look of the runners. But I'll take a look at the thread you mentioned. Do you have a link?

 

The thread comes up every now and then. The main poster on it as I remember was Dyno Don. I don't know how to do a link and I don't keep the thread in my subscription list. I understand wanting to keep the runners clean. I bought the SLP runners in 98 as I was compiling parts for my project that I completed in 99. I was disappointed when I saw them because Summit pictured them in their catalog all siamesed and ported huge. What I couldn't figure out was how I would port them all the way through, going around the bend.

As far as siamesing them. I would say you are safe to go as far as you can reach with an abrasive roll. By doing this, you are shortening the individual runners and increasing the plenum volume. This will increase your upper rpm power band. Experience, however, has shown me that to get the most top end you really need to move air. To do that you want to find a way to increase the CSA in those runners. Maybe extrude honing?

 

Here is a pic of mine which is a few steps better than yours. The ones I have seen of Dyno Dons blows anything we have done right outa the water!


Porting getting closer to finished


Here is the orginal 1st run of SLP runners. Notice they have one side thats completely open all the way thru on each runner. (2 distinctive tq peaks is what they claimed)

 

The lower photo looks like what Summit had pictured in their catalog when I ordered mine. Did they actually come from SLP that way? I was told that they could be ported to that state when I called Summit tech to complain about the difference between their catalog photo and what I received. TTOP350's ported SLPs look like they have some seriously large CSA.

I know that 89GTATransAm made 420WHP with his setup that included runners worked over by Dyno Don. That's serious horsepower.

 

I thought about honing mine, but then I found out that it costs close to $300. I had mine ported for $250. And they cost me $270 new. So total invested in mine is $520. With that figure, I should of just boughten some ACCEL's because they have larger ports out of the box.

 

One thing I wondered about was using a flexible ball hone. I looked on the internet and found a company that makes them in all sizes and grits. But then again, if you know someone who's a good TIG welder, you could have them cut open, enlarge and siamese them as much as you want, then have them welded back together. Probably wouldn't be able to tell they were ever touched.

 

With TIG welding? I would have to sand and polish down the runners to get rid of any welding.

 

You can cut the back side of the runners and it would be harder to see the mods but may also cost more to do.

 

Why didnt I think of that????? Very good idea TTOP350.

 

This fella does some serious porting. https://www.thirdgen.org/forums/album.php?albumid=4181

 

If I where to gut the SLP's, will I lose any low end torque and gain hi end torque?

 

..... Funny you mention that. His name is Darin. He ported my runners to its current state..