turn-down pipes TORQUE IS GONE!!!
 

hey everybody, i have a strange feeling about this...

i just had my exhaust pipes removed... i had the muffler guy put some turn-down pipes on my flowmasters...

the low end torque is GONE.
the car feels slower.. but i've read magazine articles that show that turn-down pipes are better for drag racing applications....

either way, i'm worried about this ...

my ONLY time at the track was last week .. i did a quick burn-out and a baby launch at 1500 rpms on street tires.. it ran 13.86 @ 102 mph.

i could have done better with a stronger launch, but i didnt want to spin.. i also granny shifted it as usual :) and my 60ft time was 2.2 :(

oh well, i still managed to smoke the ls1 z28 next to me up to the 1000 ft mark after which me walked me by 3 car lengts.. he ran 13.84 @ 106 with a crappy 2.4 60ft time.

on my previous mustang, which went high 11's on 150 shot of spray (89 lx coupe carbed 302 roller motor) i had the same exhaust setup as what i've got now.. and it was much faster.... i dont know if i've screwed this car up or not.. what do you guys think ?

I'm not surprised. You've removed a lot of back-pressure, which translates to loosing some torque. The gain in HP might be enough to compensate at the track.

Run it and let us know.

by using turndowns you are going to lose a little bit of that low end grunt, but it shouldn't be as bad as you are describing. i ran turndowns on my car for awhile and it really didn't feel any different as for as power, but my car had heads, intake, and so on. So i guess the more stock your car is, the more it could hurt it by not having enough backpressure.

It sounds good though huh? i had a long argument with some folks here about this, i really couldnt tell if i lost any torque, I dumped the clutch at 5k anyways so i guess its hard to tell, however my 1/16 mile time seemed to have gotten slower, the mph is the same or a little better on the topend, im thinking of putting on some 2-1/2 pipes back on someday....

Coupe5oh are you launching that high on stock axles?
Reason I ask is that I will be launching on slicks for the first time since I've put the T-5 in and I know that they aren't really strong, but hopefully they will hold up to atleast a 3000RPM launch
I'm not coming home without a 12 second timeslip or some broken parts :D

you can drop the hammer at 4000 rpm on stock axles and slicks if you have a good clutch ...
i know because i've done it on some of my previous stangs...




more than 4000 rpm is your risk....

i know of people who launch of the rev limiter on stock axles... but i dont know if theyve ever broken anything...


:(


good luck !

turn downs
 

i had tail pipes 2 1/2 all the way out the back the car car 12.18 @112 i put turn downs on it and it done 12.23 @110 so to much of a differents

Well i'll sacrifice a little torue for the sound my car makes, evertime im getting gas, people walk up and tell me my car sounds rowdy.

Anyway, i know of many people laucnhing on stock axles with slicks, i was launching on e.t streets, the reason i drop it so high is because of the crap gears i have, i like to get a little spin so it doesnt bogg, i only dump that high when im going for a best e.t or if i have a grudge with the ricer next to me:) really i think the axles are not the problem, its the old trusty T-5, my clutch is new, but i smelled it a couple times at the topend, also my throwout bearing is making the most annoying noise now, but that happened ever since i drove through some high water, i dont blame that on racing.

just keep the slicks to a 26x8.5 and you should be alright, i know of a guy that ran several passes on a low 10 sec car with stock axles, however he couldnt find a t-5, or tremec that could take 20+ pounds of boost, and hold together.

I have cutouts before my mufflers and with them open, it feels as if there is more lowend torque. I have run several times with my Gtech and would always trap mid-low 103's with them capped and high 104's with them open. I know a gtech has high trap speeds yadda yadda, the argument isn't about that. I find myself driving in lower rpms with them open than closed, I feel there is more power with them, so I doubt your losing any power at all having turndowns vs. piping to the rear end. I've read that you make your most power with 12 inch piping after THE HEADERS, not mufflers. Does anyone have any dyno information to verify any of our arguments. What I have written is my opinion and experience but I could be wrong and I can accept that if I am.

Well not to make it an argument myself, but the way i see it, is it's probaly a smarter move to remove the tailpipes for more flow, than install 1-5/8 equal lengths on a stock motor, you would probaly lose more lowend that way.....late:)

I always wanted an lx for the tailpipes, now i dont have them, but I think it looks good with welds and some good size meats on the back with, or without.

It's the MUFFLERS, not the headers..lol. GEEZ. :rolleyes:

Want a very graphic representation of back pressure on an engine!

Strap two 10 pound weights to your arms then go about your normal routine.

I always find the back pressure thing interesting. Anything that inhibits the flow of exhaust out of the engine creates extra work for the engine to do, sapping that much more power from the crankshaft.

Exhast systems function just like an intake when it comes to resonant tuning, velocity, ect.

Ideally you want ZERO back pressure with just enough negative pressure created in the exhaust to help draw more fuel and air into the engine without sucking it into the exhuast system (tricky thing to do).

Its interesting to note that most people install headers that are a tad bit bigger than is nessecary. I suppose combining this with a very effcient exhaust system creates very lazy exhaust flow down low in the RPM range, the net effect being a loss of torque at the bottom with the peak being shifted higher in the RPM range where the exhaust system starts to come into its own and reduces the load on the engine or helps to draw more air/fuel into the engine.

I think I seen about a 12 inch long pipe behind the mufflers of Warren "The Professor" Johnson's pro stock Pontiac.