QUESTION ABOUT PORTED SLP RUNNERS
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From: pa
Car: 87 IROC
Engine: 350
Transmission: auto
Axle/Gears: 3.23
QUESTION ABOUT PORTED SLP RUNNERS
A while back I got I set of SLP runners to install on my 87. The guy I got them from tried to do his own mega port job...I finally got done cleaning up what he did and am now working on the plenum. My question is about where the runners bolt to the base...is there any point to opening up the lower side of the runners to match the ports on an accel base? I'm no expert on airflow, but wouldn't that change the velocity of the air when it goes from the smaller diameter of the runners the larger opening of the base?
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From: Cypress, California
Car: 1989 GTA
Engine: 369 TPI
Transmission: 4L60E
Axle/Gears: 3.70 Nine Bolt
Re: QUESTION ABOUT PORTED SLP RUNNERS
The ideal situation is to carry the opening of the base on up through the runner to the plenum. However do to fitment issues/slop you may want to make the opening of the SLP runners slightly smaller so you don't have a ledge in the path of the airflow.
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From: pa
Car: 87 IROC
Engine: 350
Transmission: auto
Axle/Gears: 3.23
Re: QUESTION ABOUT PORTED SLP RUNNERS
That's what I'm thinkin. The other guy did do a little work on the lower end of the runners and they are very close to the size of the un ported superram. Still would like to know if my theory is correct about having the larger opening down stream of the smaller opening...
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From: Cypress, California
Car: 1989 GTA
Engine: 369 TPI
Transmission: 4L60E
Axle/Gears: 3.70 Nine Bolt
Re: QUESTION ABOUT PORTED SLP RUNNERS
Basically you don't want the air to be speeding up and slowing down along the intake path from the plenum to the head. So yes you are correct. Also a slight taper would be in order for the entire intake path. So the entrance from the plenum should taper down somewhat from that point to where it meets the manifold. Then there should be some taper in the intake manifold. You might not be able to do that but do the best you can. If nothing else try to at least maintain the same cross sectional area. If you do you will be ahead of most.
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From: pa
Car: 87 IROC
Engine: 350
Transmission: auto
Axle/Gears: 3.23
Re: QUESTION ABOUT PORTED SLP RUNNERS
Thanx! That being said, I'll just leave the lower side the way it is for now. I plan on upgrading to a good set of heads next winter(the original valve guides are worn) so maybe then I will get the whole intake extrude honed. My only other question would be, will the larger(than the port) gaskets cause a disturbance in the airflow? The superram gaskets have 1 3/4in diameter which is larger than the ports. Would it be worth it to get some stock runner gaskets and open them up to match?
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