I just got my SLP siamesed runners today. I want to make sure i am clear on a few things before i start grinding away. Should I make my plenum match the holes in the runners? Also, Should I port anything off of the runners themselves? Does anyone have any pics or tech articles that can help me out?
Thanks alot

 

Port match the plenum to the gaskets. Of course the gaskets should match the runners, too. It would not hurt anything to open up the volume of the runners. Dan Burke (http://www.isthq.com/~dan/efi.html) has some pics on his site. If I ever finish mine, I'll update my site with pics.
Happy grinding

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Bob '89 Formula CC350
Last(lost)Member of the Elusive Great Lakes Crew
My car's homepage

 

Here is a thread that Traxion posted on the Aftermarket Product Review board about hte difference of SLP and AS&M siamese runners. The one picture shows additional porting on the SLP runners and in the background there is a picture of the plenum too.
https://www.thirdgen.org/messgboard/...ML/000267.html

I hope it helps you some.
Good Luck!

 

Couldn't you spend a little time and make the SLP's look like the AS&M? It looks like there is enough material there that could just be ground away, and opened up.

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Rob
'86 TA 305 TPI
Gutted MAF
Ported Plenum
TB Bypass

 

Not knowing the diameter of the AS&M runners, one could port the SLPs to be similar. The hardest part is porting the inside radius. It requires a special burr to get at it due to the angle. My 1/2" tree shaped burr can only reach so far (it's 6" long). A couple of those pics posted in the other article are from Dans site.

 

More info on porting SLP runners on the post:
https://www.thirdgen.org/messgboard/...ML/001115.html


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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo
Club IROC-Z

 

Ok people, I'm gonna say this for the last time. A few years back I was looking through a GM High Performance catalogue and noticed that they had the SLP runners. I started reading what they had to say about this runners and they said that "by eliminating one of the dividers at the BOTTOM of one pair of runners on each side, they had managed to make the engine torque to actually peak twice at about 1000 rpms between peaks". Talk about flat torque. If you look at the Summit catalogue and look at the SLP Runners picture, them you can see what I'm talking about. Well, when I bought my SLPs about 4 years ago, I noticed that the looked nothing like the ones in the picture. So I put them in my car anyway and noticed no power gains at all, but torque did stay really flat. I confirmed this when I switched back to stock runners as they pull kinda like a turbo, from little to much more. So anyway, I got really pissed off and decided to mod the runners, however, I went one step further and eliminated all the dividers, TOP AND BOTTOM, about 2 inches or more inwards. I also made the diameter bigger as far as I could reach in. After I was done (It really didn't look pretty) I put them back on the engine and the car felt just a little bit better, but no big difference; there was no torque loss at all. Come to find out that as soon as I replaced my crappy a$$ exhaust manifolds for headers, then the runners gave the engine a different attitude. Now the engine wanted to rev all the way to 6000 RPMs on its own and it pulled hard all the way there. After I put the cam in (wich is pretty big for a TPI[ 230-236* duration, 510-520" lift and 110 LSA]) the engine gained a lot of power (about 40-50 horses) and never lost any torque, actually it was the other way. It had anough torque to break traction a bit at 40 MPH.
As it is now, the engine still pulls to 6000 RPMs, but falls on its nose at any higher than that (I'm positive that completely stock heads need to go). I think what I did to the runners enables the engine to rev that high without power loss. I was also thinking that by modding the runners like that, it effectively shorten runner lenght since now the runners act as a small plenum and the actual runners start at the entry of the intake manifold, as far as the engine is concerned (engine is fooled and thinks runners are way shorter).
So, I'm sure there is gonna be a bunch of skepticks and IDIOTS (won't mention names for now)who think I'm crazy, but I know what I have and the numbers prove it.
Rick

ps: my best numbers so far is 13.40@104.....I'm going to the track tonight, weather permitting and I am pretty sure I'll be running 13.30 or better. Why? After I put my new damper, I found out my timing was a little bit high, right at 16* because the outer ring on the stock damper had slipped, so basically I had to adjust the timing blindfolded. I have it now at 9* and will play with it at the track, but I can tell you it feels much better.


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'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, intake pieces and 2100 RPM TQ

13.40@102.55 MPH
1.90 Sec ------- Best 60FT
104.23 MPH -- Best Trap Speed

AIM HIGH!

 

This is the "Greg90iroc" method of porting the runners and the plenum. Get you some red spray paint and bolt the runners up to the plenum. then from the other side spray the paint into the plenum and grind off the area that has red on the mounting flange. also do the same for the plenum side by looking at the spray patern on the runners. I could not get much on teh plenum by spraying through the runners the other way but you might have better luck. gasket matching is not as exact and harder to do. Then clip the gaskets to make sure there is nothing hanging in the air stream and you are done. Oh yea you want to get the paint out of the intake too use autozone carb cleaner.

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90 iroc l98
last season best corected 13.62 @102
mods
full exhaust, AFPR, pulley, jet stage 1 chip, billet servo, 52mm throttle body and a few other little things.