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Old 05-15-2007   #41
Fred91GTA
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by DUBGTA88
Is that what siamesing is to have no gap between the runners? Thats what I should try to do with my runners and intake base right? And what is the 400 sbc?

Yes, that is what siamesing is. It's very difficult to do with the SLP Runners. You will not be be able to siamese them all the way because of how the runner bends. That's why I only siamsed mine about an inch down. Even with that 1 inch, the car revved much better than it did with stock runners.

The 400 SBC is the 400 cubic inch small block chevy. Made in the 70s, came from the factory with 400 cubic inches (6.6L). Had siamesed cylinder walls since the bores were so big that cylinder wall thickness became an issue.
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Old 05-16-2007   #42
DUBGTA88
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Fred91GTA
Yes, that is what siamesing is. It's very difficult to do with the SLP Runners. You will not be be able to siamese them all the way because of how the runner bends. That's why I only siamsed mine about an inch down. Even with that 1 inch, the car revved much better than it did with stock runners.

The 400 SBC is the 400 cubic inch small block chevy. Made in the 70s, came from the factory with 400 cubic inches (6.6L). Had siamesed cylinder walls since the bores were so big that cylinder wall thickness became an issue.
Wow sound like a good block. Well I just got my slp and I love them. But you guys are right out the box they need some work. I notice that the gaskets they gave me match my intake and my plenum perfect. But when I put them on the runners in some places it looks like the gaskets are to short and in some places to long. So if I would to install them they wont match with all my stock parts. I guess this is were all the porting will kick in right?
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Old 05-16-2007   #43
FearThisGTA
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Re: Good Deal On Some Slp Runners!!!!!!!!

Yes,that is correct.
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1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 05-16-2007   #44
Fred91GTA
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Re: Good Deal On Some Slp Runners!!!!!!!!

That's exactly why I went bigger. In some parts, the gasket was too small, in others, the gasket was too big. So I just went a size bigger. The gaskets they gave you are stock size TPI gaskets. This is why some people buy them and slap them on out the box and run slower than they did with the stock stuff.

It'll take some work, but it's well worth the time and the effort.
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Old 05-16-2007   #45
DUBGTA88
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Fred91GTA
That's exactly why I went bigger. In some parts, the gasket was too small, in others, the gasket was too big. So I just went a size bigger. The gaskets they gave you are stock size TPI gaskets. This is why some people buy them and slap them on out the box and run slower than they did with the stock stuff.

It'll take some work, but it's well worth the time and the effort.

I also noticed that on the gaskets that they have some out lines that you can cut out in to a bigger perfect round shape. I think thats what im going to do. Just cut the gaskets to a bigger size and then port the sh** out of them to match. Im thinking of making the top part of the runners into a seamesing shape as far in as possible. I was thinking of doing the samething to the plenum. But Im not sure if I should. As for the intake base I was planning on just making the holes bigger and doing the samething to the lower runners. Any other pointer you guys might have before I get started?
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Old 05-17-2007   #46
Fred91GTA
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Re: Good Deal On Some Slp Runners!!!!!!!!

I ported the plenum to match my runners. Doesn't make sense to leave the plenum alone and have that divider there to block some of the siamese. Just go slow and take your time. Better to take longer and do it right than to royally mess something up.
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Old 05-17-2007   #47
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Re: Good Deal On Some Slp Runners!!!!!!!!

To siamese your intake...

Siamese Runners

This gives you an idea of what to do. The stock runners can be modded to look like the SLP ones. Not easy, since they are cast aluminum, so it would make welding to them tricky.
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Last edited by Stephen; 05-17-2007 at 04:26 PM.
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Old 05-17-2007   #48
DUBGTA88
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Fred91GTA
I ported the plenum to match my runners. Doesn't make sense to leave the plenum alone and have that divider there to block some of the siamese. Just go slow and take your time. Better to take longer and do it right than to royally mess something up.
Thats true the runners need to get some air. Did you also siamese the intake base? Or did you leave that alone?
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Old 05-17-2007   #49
DUBGTA88
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Stephen
To siamese your intake...

Siamese Runners

This gives you an idea of what to do. The stock runners can be modded to look like the SLP ones. Not easy, since they are cast aluminum, so it would make welding to them tricky.
Do you recommend doing the siamese to the intake base or just matching it to the slp runners? The reason I ask is becouse that guy on TGO has a 383ci in his car.
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Old 05-18-2007   #50
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Re: Good Deal On Some Slp Runners!!!!!!!!

I wouldn't go too crazy, with a mild 350. But, smoothing the "divider" in the base, into a smooth V shape, instead a flat wall should help. Same with the plenum. Concentrate on smooth V.

I'd say extrude hone the runners, it helps, but it ain't cheap!
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Old 05-18-2007   #51
DUBGTA88
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Stephen
I wouldn't go too crazy, with a mild 350. But, smoothing the "divider" in the base, into a smooth V shape, instead a flat wall should help. Same with the plenum. Concentrate on smooth V.

I'd say extrude hone the runners, it helps, but it ain't cheap!
So just do some mild siamesing to the base. As long as it still has the center divider and it looks like a V right? How do you extrude the runners?
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Old 05-18-2007   #52
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by DUBGTA88
So just do some mild siamesing to the base. As long as it still has the center divider and it looks like a V right? How do you extrude the runners?
Yep, you wanna keep some divider, just make it a smooth V transition.

Extrude Hone.com or just get some Edelbrock or SLP siamesed runners.

Go crazy, and do the LT1 plenum conversion. No more higher RPM (above 4500) restriction.
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Last edited by Stephen; 05-18-2007 at 01:39 AM.
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Old 05-18-2007   #53
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Re: Good Deal On Some Slp Runners!!!!!!!!

Extrude Hone

Chevy TPI Upper
Level I- $175.00
Level II- $255.00
Chevy TPI Lower
Level I - $395.00
Level II- $475.00
Chevy TPI Tubes (Runners) per pair
Level I - $245.00
Level II- $325.00
Chevy TPI Upper, Lower, & Runners Combo
Level I- $730.00
Level II- $810.00
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Old 05-18-2007   #54
DUBGTA88
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Stephen
Yep, you wanna keep some divider, just make it a smooth V transition.

Extrude Hone.com or just get some Edelbrock or SLP siamesed runners.

Go crazy, and do the LT1 plenum conversion. No more higher RPM (above 4500) restriction.
Well I dont want to go to shoping crazy. I already bought a set of slp runners im just trying to find out how much I should siamese.
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Old 05-18-2007   #55
Fred91GTA
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by DUBGTA88
Thats true the runners need to get some air. Did you also siamese the intake base? Or did you leave that alone?
I left my intake base alone. I didn't see the need to siamese my base. Besides, I read on TGO that a lot of guys that did this mod to their intake base had problems with burning up their pistons. Apparently, siamese too far in and cylinder 5 steals fuel from cylinder 7, causing a lean condition in cylinder 7, causing a melted piston. This happens because 7 is right after 5 in the chevy firing order. More trouble than it's worth for me.
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Old 05-18-2007   #56
DUBGTA88
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Fred91GTA
I left my intake base alone. I didn't see the need to siamese my base. Besides, I read on TGO that a lot of guys that did this mod to their intake base had problems with burning up their pistons. Apparently, siamese too far in and cylinder 5 steals fuel from cylinder 7, causing a lean condition in cylinder 7, causing a melted piston. This happens because 7 is right after 5 in the chevy firing order. More trouble than it's worth for me.
Thats true dont want that kind of trouble. I think what im going to do is just try to get my runners to look like the fisrt design. They say that in one side of each runner it was missing the divider. So im going to try to do that. I think they said in the passenger side it was the front and the driver the back.
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Old 05-18-2007   #57
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Re: Good Deal On Some Slp Runners!!!!!!!!

You could always do the cam firing order swap. There are new cam available, that change the firing order. That might even cure the 7 stealing fuel from 5 problem.

It swaps 4 & 7.

One story I found online...
Comp Cams
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17x9 275/40s front/17x11 315/35s rear custom widened & powdercoated ROH Snypers--02 Rear wing
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Last edited by Stephen; 05-18-2007 at 10:35 AM.
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Old 05-18-2007   #58
FearThisGTA
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GTA Year: 1991
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Re: Good Deal On Some Slp Runners!!!!!!!!

^ yeah, I been kickin around that 4-7 swap fer awhile.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 05-18-2007   #59
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Re: Good Deal On Some Slp Runners!!!!!!!!

Comp Cams is listing the FI and TPI cams separately, and the 4/7 swap cams separately. I shot an email to them to ask about a 4/7 swap TPI cam. I'll post their reply.
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Old 05-18-2007   #60
Fred91GTA
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Re: Good Deal On Some Slp Runners!!!!!!!!

Quote:
Originally Posted by Stephen
You could always do the cam firing order swap. There are new cam available, that change the firing order. That might even cure the 7 stealing fuel from 5 problem.

It swaps 4 & 7.

One story I found online...
Comp Cams
You could, but why? I see no point in going that route. People have been experimenting with the firing order of the small block chevy since it first came out. And it's still made the same way with the same firing order as when it first came out. I just prefer keeping things simple anyway. Besides, the firing order is stamped on my intake manifold... Good reference.. haha
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