I have a 1988 L98 GTA ported upper plenum, 3.73 gears, Edelbrock Catback, 1 3/4 SLP Headers, High Flow Cat, Cold Air Intake, All free mods.

With my setup the car peaks it's horsepower to soon....the Goodyear GSC's hook up great so I don't spin too much off the line. Should I invest in AS&M Large Tube Runners or AS&M Semi-Siamesed Large Tube Runners? Anyone have ay experience with aftermarket runners that can share the performance gains?

I have stock cam and heads.

 

Just testin' the sig!

------------------
1988 L98 GTA
3.73 Posi
Polished & Ported Plenum, JET AFPR
Free Mods, Cold air Intake
Subframe Connectors, Strut Tower Brace,
SLP 1 3/4" Stainless Headers, Edelbrock Catback, Catco. converter,
Goodyear P255/50R16 GSC's

 

I have never personally used AS&M stuff, but I've always heard nothing but top-notch comments about them.

The LTR's supposedly only increase the power over the powerband while keeping the powerband and power peak similar. The siamesed runners tend to sustain or loose a little low-end torque due to velocity while at the same time making the powerband 'flatter' and raising the power peak alittle due to increased maximum flow. If you can port I would definitely recommend the SLP siamesed runners if you decide to go that route, they're $250 new and have plenty of room for porting. If you still spin a little and like a helathy top-end, I would recommend siamesed runners, while the LTR's are better for those who love low-end torque and don't rev much. Your choice.

 

Oh, by the way, aftermarket runners will more than likely need to be matched to both the upper and lower intakes. What kind of intake base are you running? You'll see a small gain with the runners if the stock unported base is there. I would also recommend at least a healthy base porting in addition to matching, and while it's off, pop in a healthier cam, it's easier with a roller setup. That is if you're looking for more power. These parts can be often found at great deals in the classifieds if you're on a budget. Just make sure they match.

 

ttt

 

after looking at asms crappy welds in the siameased set i sent them back and got the ltr's hopefully it was just a crappy set but asm looked at them and said that most were like this so i asked for the ltr's i could have cleaned them up maybe with a flex shaft dremel but when you pay 500 bucks they shouldent need any work.besides the sc will push the air through in my case
pete

 

There is a guy on the wire here who goes by the handle of Jerry Who. He hangs out in the Southern California section. Anyways he is running the AS&M large tube runners with TPI mods to the plenum and aftermarket manifold. He is running in the 12.5's in the quarter mile and shifting around the 6200 mark for his best times. Kinda blows some theories away doesn't it. Allen

 

There was an article around here posted that had dyno numbers comparing different intakes. A few LTR setups were in it, including an AS&M setup. The dyno's were all done on a 89' L98 Corvette with a CAI and edelbrock headers and exhaust I believe.


For the most part the AS&M setup with a stock ported base was THE best performing intake it seems. Making more power than the First Injection TPI setup up to 4,500rpm, after that the First setup made a bit more power at 5,000rpm.

 

They didnt include the edlebrock runners . I have seen the SLP ...and Edlebrock back to back ....and the SLP 's were a bit smaller in diameter than the edlebrocks

 

This is something I was asking in an earlier thread. What is the differences with Edelbrock and AS&M runners? They're close to the same diameter aren't they? I guess the difference may be in the actual runner length maybe? Anyone know these two runner's spec's for those?

 

Personally, I'm partial to the Big Mouth / AS&M LTR set up with the TFS TW G1 heads. I ran it for years for the performance and for the stock look. You really have to know your stuff in order to catch it, especially the way it was set up in my car. Granted I spent time trying to make it look stock. Now the motor is out and I'm debating an LT1 conversion. :shrug:

 

The SLP's seemed shorter .....but they were definatley smaller in diameter.

 

Pulled this off of Stealthram.com take the data as you will. I can't verify its accuracy, though it does seem accurate.
http://www.stealthram.com/flowcomparison.html

Intake......runner length .... port in...... out
Stock GM Base----- 6.375"------------- 1.47"------- 1.96x1.20
TPIS base------------6.125"------------- 1.75"------- 2.09x1.28
Accel base-----------6.125"------------- 1.75"---------2.09x1.28
Holley base--------- 6.000" ------------ 2.30”-------- 1.90x1.23 (2.337 sq inches)

Runners
Stock TPI-------- 7.250"------1.470" round(1.70 sq inches)
SLP -------------- 6.625"------1.600" round (2.01 sq inches)
Accel LTR------- 6.625"------1.615" round (2.05 sq inches)
TPiS-------------- 7.625"------1.660" round (2.168 sq inches)
Mini ram --------3.500”
stock MRII with 1204 (AFR 195) ports, 58MM - 265 cfm
stock MRII with 1206 (AFR 220) ports, 58MM - 281 cfm
MRII clean-up, 1206 ports, 58MM - 292 cfm
MRII cut, weld, port, etc, 58MM - 321 cfm
LT1 ----------3.000”

Runners (measured individually)
Stock........................................................................................................................................203.17 cfm
ACCEL.....................................................................................................................................242.02 cfm
Extrude/ACCEL........................................................................................................................275.83 cfm
Super Ram................................................................................................................................289.18 cfm
Intake manifold with 3/8 inch radiused inlet .............................................................................222.45 cfm
Holley stealth ram ………..........................................................................................................275.00 cfm


Stock intake manifold with runner
Stock.........................................................................................................................................198.72 cfm
ACCEL......................................................................................................................................213.52 cfm
Extrude/ACCEL.........................................................................................................................217.11 cfm
Super Ram.................................................................................................................................220.67 cfm
Holley stealth ram ….................................................................................................................275.00 cfm
ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet.....................................................251.51 cfm
ACCEL Hi-Flow intake manifold with runner Stock...................................................................215.83 cfm
ACCEL......................................................................................................................................232.53 cfm
Extrude/ACCEL.........................................................................................................................243.21 cfm
Super Ram.................................................................................................................................240.24 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet.............................275.83 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with ACCEL runner.......................................266.94 cfm
Edelbrock Performer RPM manifold (Stock)...............................................................................286.51 cfm
Edelbrock Victor Jr....................................................................................................................275.24 cfm


Runner Length


Stock TPI manifold ...................8” ...............runners 11.25”............... cylinder head 6”.............total 25.25”
Accel super ram manifold........ 8”................runners 7.00”............... cylinder head 6”............ total 21.00”
Holley stealth ram manifold .....6.26” ................................................. cylinder head 6”............ total 12.26”
Edelbrock performer RPM ...........................runners 6.00”................ cylinder head 6”............ total 12.00”
Edelbrock Victor Jr .......................................runners 5.50”................ cylinder head 6”............ total 11.50”

 

Hi,

If anyones interested, I have Asm base and large tube runners
with the optional nitrois bungs.
Can hook up for nitrois or plugged as they are now.
No trottle body.
All hardware though.
$200.00. Like new!
Went to Miniram.

Rather someone close as don't want to ship or need to sell that bad.
Prescott,AZ

Later
jaykar

 

Dibs?

 

Hi,

Like I said, setup is as stated and also includes 22# injectors
which I didn't include and probably another set which came
off an 86 vette which accuired and also believe are 22#.

But also don't want no see, and shipping hassles so, if close
to me would rather do it that way or am going to put in local
classifieds.
No BS, is as stated.
Ordered this from ASM complete, less Throttle Body.
Also have the distributor cover to go with it and the hardware
plus engine bay hardlines.

Later
jaykar

 

Well, if you feel like packing it up let me know. Actually, PM me where you're at, I have a friend out that way, he may take a ride to get them.