I'm curious just how restrictive my setup is. The motor in the Sig ran a 14.45 with SLP 1 3/4 headers, Fourbolt flange cat ( walker corvette cat) and SLP fourbolt flange exhaust. I just measured my back pressure and it is 4-5 psi at 5000 RPM. I need an assistant to check it at 6000.

I would like a survey of ET's and engine combo's please be specific and give a detailed description of your exhaust. Dual cats too please as well as no cats.

 

Well if that's with the motor in your sig and you run a mph suitable to that ET, then you've got some problems. Unless your at a high elevation.
My '92 is nearly completely stock, granted with the dual cat setup (which doesn't help a whole lot anyways), and runs faster. What is your mph? It is much better to use than ET when diagnosing power problems.

 

Oh, and for a previous engine on the '88:
357
aluminum L98 heads
Comp 08-302-8
Stock TPI components (mildly ported base and plenum)
Edelbrock TES 1 5/8 headers (BAD)
Stock 3" cat
Edelbrock 3" cat back

13.7 @ 101 on street radials

 

it went 97 MPH

 

I went 12.97 @ 109 with SLP 1 3/4 headers, both cats going into the 3" slp system. Others have gone much faster.

I think you have an air intake problem. You need a single plane and a 750 double pumper.

 

Didn't the TT Lingenfelter have 2 or 4 cats?

 

Jeff Stevens went 9.98 @ about 130 Through a Single Cat.

 

your cat isnt the problem, its definately the stock carb. that little "microfourbarrel" is starving the 383. the eps isnt a bad intake, and is definately legal. i didnt notice where youre from, but if its cali, your stuck with the carb. my suggestion? order a rejetted q-jet from JET performance in long beach. up to 650 cfm on a stock carb. no guarantee itll pass emissions, but itll pass the visual. and that should solve your low times. that and some tires

 

9.98 through a single cat? Your leaving outt the details i asked for!!

 

355 afr 190/superram/slp 1/3-4/banks 3 inch single cat-13.0@ 104

 

Damn, I woulda thought with all the hype AFR's have that they would run faster than 13.0 which seems to be the norm around here!! DAmn, my cast iron headed vortec 350 in my firebird goes mid 12's with a basic combination.

 

I'd think that would be a bad choice for that setup, assuming his cam starts power after 1500 or so.

 

bad choice for the setup? probably. but im assuming that hes trying to keep legal. if not, there are a hundred better ones.

 

actualy its a low rise performer with egr, i know its not optimal but i wanted to remain legal, in fact the only part of my car that isn't legal is the cam. i wasn't familiar with the stealth line of manifolds at the time. I would think a performer rpm would be a good match but it won't clear the hood and no egr so it won't pass a visual. the stealth supposedly makes more power but i would like to know how it compares to the RPM in terms of flow. There is also a single plane stealth with EGR that i am interested in but i don't know how it would effect emmissions, mileage, or low end. right now its a tractor at low rpm, in fact downshifts are rarely neccessary. I would like to open up the exhaust some what before going to a single plane.

does anybody have any info on the stealth, both dual plane and single.

 

afr's going 13.0-hype.

try it on stock gatorbacks @ 3650 lbs weight. As for extensivly ported. These are out of the box heads w/ 199.156 valves(set up for 305.

 

0.060" over 283
Performer RPM cyl heads
Performer, 600 cfm vac sec
Comp 286H hydraulic
shorty headers w/Y-pipe
2 1/2" cat-back, no catalyst
3.42 open rear, T5 w/4.03 1st

14.18 to 14.65 at 104 MPH according to G-tech Pro

 

keep them comming!

is anybody out there running the singleplane stealth, i think its the 7525, has egr and says it fits under the hood of 3rd gens

 

Hype? Maybe you are referring to just a 305? A 350 even with a mild cam should run easy 12s with the commonly used AFR 190 and decent stall/gears. I'd sell my car if I could only muster 103/104 with AFR's and a decent cam. Don't people tune their cars anymore?

 

I'm running a Weiand Stealth, with a 3'' filter and fits fine. I had to ditch my carb 1'' spacer and 4'' filter though.

 

you need at least 400 hp to run mid 12's. Z06's can only do 12.6-8's what are you running???

AFR's are not magic bullits, they flow slightly better than vortec's. besides they are only 190 cc runners

 

which stealth are you running? the big dual plane isn't available for a spread bore, it says 0-6800 rpm thats what i think i need.

 

Laiky,

Some of these guys are total boneheads! What do you think this guy payed for his Daryl Young trans? More than the AFR 190's im sure. How about extensivly prof ported Vortec heads? My car"the 1 i should sell ran 13.0s on stock Gatorbacks w/ a 2000 stall conv. The cam was a mild hydraulic only 216 @ .o50 lift. This was a street car not a race car. There are lots of big mouths out there that have never even been to a track but can run: mid 12's".