irocnroll89

iTrader: (4)

which is better and why? The slp are defintely cheaper and they say they are better for over-all performance than LTR'S. What do you guys think???

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'89 SHAGGY IROC
L98 7r4, all free stuff,T.E.S.,HOOKER CAT BACK,KYB,ACCEL8.8,JET fan sw. etc.
so much to do , so little money

mirage2991

I got the old style slp's and edelbrock base. I got the hole set up for dirt, and I mean dirt...I did a terrible port job on the plenum cause I didn't have enough time...and I have no track time yet, but in overhole, it seems to make a difference. Before the intake, the engine never ever went above 5K (on my sport comp tach) and the other day it went to 5250 twice. Hopefully I'll have some track time by next week to post.
One regret: Wish I had changed cam, cause I'm sure that would have really wake up the car.


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85 Z28, 355, edelbrock base, SLP runners (old style) 58mmTB, ported plenum, stock cam, fuel reg, TES headers, flowmaster, 3.73's, shift kit, MSD 6a, 305 hypertech chip (YUUUCK!) best prior intake mods: 14.6 @ 94, 2.02 60' temp: 78deg, 80% moist, on radials.
69SS, black, 3,73's, TH400, 402 BB, roller everything (solid 246@50 622 lift)+stud-guirdle, 67 Vette heads ported and o-ringed, about 10:1 cr KB pistons, should be done this summer, goals: 500hp and lots of fun

Grim Reaper

Get the Large Tube Runners from AS&M...those are the exact same runners that TPIS sells (at a higher amount).

As flow goes, the AS&M LTRs (or resold as TPIS) are superior.

Kevin91Z

iTrader: (1)

I agree with Glenn. I have the TPIS runners (bought them used) and I've seen SLP's runners. I'll stick with mine. The AS&M's are the exact same as TPIS' runners, as TPIS buys them from AS&M.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

ws6transam

SLP runners are budget performance for budget price. They are a decent value for the money. However, I agree with Glenn and Kevin, that if you wish to spend the extra dollars for the TPIS, or AS&M runners, you will see that they outperform the stock SLP runners. Whether or not they offer $150 worth of additional performance is probably the key question!


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Daniel Burk
http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Turbine Technologies 2500 stall converter, underdrive pulleys, Crane Hi-6 & more.
1.05g skidpad verified.
New best E/T! 14.039 at 100.82 MPH in 41 degree air at Stanton, Michigan.

Kyle F

SLPs are not budget price for budget performance. They work in a different manner. The are shorte, larger, and flow differntly that stock. What they do is "Tune" you intake to flow better at Higher RPMs. The are also Siamesed so there is a little larger opening at the top so it can flow at 100% capacity at all times by redcuing turbulance. After putting in a cam I later replace the stock runners with the SLP units and ported the Plenum to match, I felt a difference and picked up .3 in the quarter which got me down to 14.3 form a 14.6. This had a lot to do with the fact that the SLPs were beter suited to the cam than the stockers. With the one from AS&M I would not have seen this much improvement. You might if your engine doesnt have a higher RPM cam or heads.
Just my personal experience, but the SLP runners are designed with a different Idea in mind. The physics and engineering equations prove it.

tastedapain

CHECK OUT MY ADD IN THIS SECTION FOR EDELBROCK TPI SYSTEM WITH TPIS RUNNERS...THEY STOMP SLP!!!! TRUST ME...IVE DONE EXTENSIVE DYNO WORK WITH ALL RUNNERS AND TPIS AND ASM ARE THE BEST AND IDENTICAL.ALL POWER NUMBERS ARE IN MY AD.....CHECK IT OUT...FEEL FREE TO ASK ANY QUESTIONS....HAPPY RACING!!!

IROCKZ4me

If you view my reply to this other post you can see how I modify the SLP runners to fit different applications.

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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro

• 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

BadSS

I've seen other post where folks are removing some or all the divider in the cast runners and claim they're shortening the runner length by doing so. I'm not so sure you're shortening the runner length. Example, if you take two 7" long runners with a round diameter of 1.5", remove the divider, now you have one runner that's still 7" long with an oval opening a little more than 1.5" x 3", correct? Haven't you just increased the diameter and flow capacity of the runner by "sharing / siamesing". The SLP would be an excellent way of doing that,,, remove a little at a time until you quit picking up et,, cause I'd think you would want to keep the runners as long and as small as possible,, while still supplying the necessary air flow to the heads. However,, I'd think you haven't really reduced the length of the runner at all, and if any it would be a minuet amount directly at the plenum area?? However,, I'm not sure and don't have the time or energy to fully research. I guess the bottom line is,, who really cares how you get an increase in power as long as you get it,, huh?? Anyway,, Tracy or any one that knows with 100% certainty please chime on in.

Kevin

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86 IROC - 9.8:1 - 355, TFS twisted wedge heads, 218/228-110, fully ported GM base and plenum, SLP runners, 52mm BBK, 24# SVO, 88 350 GM EPROM, 1 5/8" Headman headers, 2.5" Dynomax, TH350, 2200 stall, B&M Megashifter, 3.23 peg leg, 245/45ZR17 on 212 Eagles - Best run - 12.53/112.4 on 26x11.5 ET Streets.

IROCKZ4me

Of course you are shortening the runner. Not the outside dimensions of course but you are shortening the port dimensions.
Total intake port length is defined as the length from the valve seat to where the port joins with any other port, all other ports, or the atmosphere.
This includes the length of the cylinder head intake port, and in the case of a TPI manifold it also includes the manifold base, and the runners to the point that two or more ports join.
In a Hilborn "stack" type fuel injection system, total port length is the distance from the intake valve seat through the heads intake port, through the manifold, through the throttle bodies, through the stacks to the atmosphere.
One a carb or TBI set up total port length would be the distance again from the valve seat through the head, then through the manifold to port entry in the plenum under the carb or throttle body.

An artificial ram effect can be attained by port length tuning. This works the same as a port in a bass reflex speaker enclosure.
The port length is tuned to a certain frequency. At that frequency port resonance increases the volume, or in the case of the intake tract it increases flow volume.
Basicaly, the longer the intake port the lower the RPM that the RAM effect takes place. If the intake port is shortened the RPM that the ram effect occurs at will be higher.
If you shorten the port length enough eventually you will reach a point where the ram effect is lost. There is no artificial boost at that point but the RPM that best power is made still rises even beyound this point. That is because a colume of air has mass. The longer the column of air, the more mass it has. With this rule you can see why an engine with a stock TPI manifold can't make power at high RPMs. The large mass of air can't get moving fast enough from the time the intake valve opens to when the intake valve closes to get enough air in the combustion chamber at high RPM. At low RPM the air mass has plenty of time to get moving and fill the cylinder. with the added cylinder filling from the ram effect an engine with long port length like a stock TPI can make very strong low and mid range power.
If you are building an engine that will make high RPM power you can't have the cylinder filling restrictions at high RPM that a long intake port has. That is where a Victor Jr, LT1 manifold, or TPIS Miniram comes in to play. They don't make the best low RPM torque but they more than make up for it as the engine revs into higher RPMs.

for the best midrange power and broadest power curve a medium length port is best. The LS1 manifold and Accel Super Ram where designed for this range. The best over all compromise for power at low, mid and high RPM is a manifold with medium length runners.


As you can see, sizing the port length to fit the rest of your combination is of utmost importance.
It would do little good to put a stock TPI manifold on a radicaly cammed, big port headed engine that craves high RPM.
That would be a little time consuming and once you got to the point of slowing down you would have to go back and weld up the septum to get back optimum.
You need to know the length of runner that you need to match and best compliment your other engine components befor you start port work.
That depends on the rest of your combo. An engine that is radically cammed and has heads with a big intake port volume will need shorter runners with a larger diameter to prevent high RPM restriction. Some times you might even want to go with a manifold port diameter that is a little too big.
That will reduce low RPM power and can actually make a very powerful car quicker because it is easier to hook up to the strip.
But basically you are correct in that you usually want to keep port velocity as high as you can, but in the RPM range that your engine combo works best.


Actually I have seen All of the septum in a set of SLP runners removed they were completely hollowed out inside, You could put your hand all the way through them. LOL The manifold base on that car was siamesed too, about half way down the port. It was installed on a 355 with ported 220cc AFR heads. It made max power at 7400 RPM. Just looking at it you would think it was a simple set of SLP runners on an engine that would do good to turn 6000RPM. lol. The ones on my IROC-Z have a 1" long septum. That puts my total runner length in between that of a Super Ram and a Mini Ram.

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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro

• 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


[This message has been edited by IROCKZ4me (edited February 03, 2001).]

88TAGTA

thanks IROCKZ4me. it's information like this that makes these boards so usefull.

IROCKZ4me

Remember total intake port length is what decides the RPM range that the engine will be most efficient and what RPM it makes it's power at.
Total port length is the length from the intake valve seat to the point where two or more runners come together or open to the atmosphere, whichever comes first.

I dug up some lengths.[*]length from the intake valve seat to port mouth in a sbC head = 6.125".[*]A stock TPI manifold base = 8.0"[*]Stock TPI runner length = 11.25[*]Thickness of plenum wall = .25"[*]That makes a total port length of 25.625" + around .2"-.3" for gaskets.

Some other total lengths from valve seat to plenum:[*]Accel Super Ram = 21.125"[*]stock base + stock SLP runners = 23.375"[*]my combo = 15.125"

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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro

• 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



[This message has been edited by IROCKZ4me (edited February 04, 2001).]

BadSS

"Total intake port length is defined as the length from the valve seat to where the port joins with any other port, all other ports, or the atmosphere."

Uggghhhh,, I should have known that. Major brain fart. Thanks Tracy.