open headers

[99formulam6]

how does eveyone feel about them? i had to take off the exhaust to pull the tranny b/c i dropped something in the bellhousing :( but when i put it all back, i decided to leave the exhaust off and start the car.

hot damn i loved it. i stopped by an exhaust shop and bought two 16'' sections of 3'' pipe and used bandclamps to secure it to the headers so i wont fowl the o2's.

it is ungodly loud, and i love it. you can hear the cam alot more than you can with the 3'' duals on. it sounds like a real race car now. :lol:

[gettinthere]

I like it but I don't like it if that makes sense. I like how loud it is, but I hate how sloppy it sounds @ WOT.

[99formulam6]

i love it. i just wish the power was still there. i feel so slow, but it sounds so fast.lol.

[gettinthere]

On stock cubes you need the back pressure to help the power.

[99formulam6]

yea, i know that. but i wish there was a happy medium. im thinkin of taking off the bullets i have in my duals to see what it sounds like...

[gettinthere]

It'll be louder, no doubt.

[99formulam6]

do you think there will be enough back pressure though? right now its 3'' duals with 16'' bullets dumped at the axle. im worried about backpressure w/out the bullets..

[gettinthere]

Running it all the way to the axle helps. You should be okay.

[CamTom12]

On stock cubes you need the back pressure to help the power.

NOOOOOOO!!!!!!!!! :)


Without backpressure you will make more power.

it's the lack of negative pulses that's hurting your torque. Should shift your torque peak higher though.

Your Y or X junction is what creates the negative pulses in the exhaust and helps 'tune' your torque peak.

[gettinthere]

NOOOOOOO!!!!!!!!! :)


Without backpressure you will make more power.

it's the lack of negative pulses that's hurting your torque. Should shift your torque peak higher though

Won't an open ORY make more power than open headers?

[CamTom12]

More seat of the pants power, yes. The Y helps shift the torque peak down to a level that we use more on the street every day.

Why else would guys run header extensions only at the track?

[gettinthere]

But still, extending the air flow does the same basic thing. It adds slight back pressure.

I'm not saying anything is monumental, but maybe 2 ponies.

[CamTom12]

No, all backpressure is bad. All it does is fight the exhaust pulses coming out of the motor.

A Y or an X actually create a 'negative pressure' wave that sucks the gas out of the chamber. Tuning your exhaust is changing where in the RPM band that happens, which in turn moves your torque peak around

[gettinthere]

Makes sense.

[Jaberwaki]

I'm glad someone else gets this...
I hear back pressure bla bla bla all the time and it gets annoying explaining why it "feels" like there is more power with back pressure...

simply put the less pressure the further up the rpm band you will make power, and you will make more of it, the trade off is low end grunt and SOTP for more power and lower ET's ;)

[99formulam6]

so your saying im making more power w/ the open headers...but it just doesnt feel like it since the torque is higher up in the rpm band..?

[CamTom12]

yup :thumbsup:

[five7kid]

More peak power - maybe.

But, more area under the curve power, probably not.

I was trying to get the '57 up to 100 mph at altitude, opened the headers to try to enhance that. After failing in that quest, I keep it corked up for the rest of the season, it was quicker and faster all year with the full exhaust than it was with the open headers.

Of course, I have a fairly mild cam, so a healthier cam would probably change that somewhat. However, collector extenders are the right thing because of the pulse tuning described, not because they increase "back pressure".

[99formulam6]

ok, so having the open headers wont help me racing from a dig then...?

i only ask b/c i have a race on sat night against a TT 97 Cobra. I raced him 2 weeks ago on street tires, and from a 1st gear punch with me spinning, i stayed right next to him. and from a dig with me spinning he was ahead by half a car....now i have on Nittos, and im running him again this sat night.

should i put the exhaust back on?

[1970judge]

You lose backpressure not to mention during winter can burn up your valves.

[Jaberwaki]

More peak power - maybe.

But, more area under the curve power, probably not.

I was trying to get the '57 up to 100 mph at altitude, opened the headers to try to enhance that. After failing in that quest, I keep it corked up for the rest of the season, it was quicker and faster all year with the full exhaust than it was with the open headers.

Of course, I have a fairly mild cam, so a healthier cam would probably change that somewhat. However, collector extenders are the right thing because of the pulse tuning described, not because they increase "back pressure".

what are you spinning your motor to?

if your worried about power under the curve while your racing then you are dropping below the curve between shifts...

while racing mine dont go south of 5900 rpms. shifting at 6800

if you are putting your powerband up higher , then you have to spin the motor higher to use it...

[Blown 25thT/A]

IMHO....I felt more power with open headers then I did with full exhaust. Since the cop across the street was nice enough to warn me about all the other cops trying to give me a ticket for too loud, etc, etc.... I was nice enough to put new exhaust on. Even with 2.5 true duels over the axle, I miss the power from open header.

[five7kid]

Stall 3500, shift 5600.

I was surprised at the results myself.

[99formulam6]

well, im meeting the TT Cobra tomorrow, and ill get a few runs in for fun w/ the open headers and see how things go. if its bad, ill toss the TDs back on for sat night :)

[Jaberwaki]

Stall 3500, shift 5600.

I was surprised at the results myself.

you said it right there brother....

your shifting at 5600 is bringing you well under the curve every shift, that is why you need all the low and middle end grunt,

5600 is the middle of my powerband
and my stall is (advertised) 4000 flashes to 4300 on the T-brake... i am under the curve for 60' after that it is all top end pull.... :thumbsup:

[99formulam6]

well, i raced the TT cobra with the open headers and won. he put in ear plugs too :) ive ridden in his car a few times and that shit is sick. when he hits full boost at like 3800, there is so way hes getting traction. and thats the only reason i won, and im ok with that. :) on the highway i dont stand a chance :(

[gettinthere]

Winning is winning!

[Jaberwaki]

Winning is winning!

it doesn't matter if its by an inch of a mile.... :lol:

[gettinthere]

it doesn't matter if its by an inch of a mile.... :lol:


Ask any racer, any real racer.............

[Jaberwaki]

Ask any racer, any real racer.............

oh yah.... make sure your double clutchen like you should...;)

[gettinthere]

Of course. It goes with the granny shiftin'.

[Transamman25]

I have a freind who works at an exhaust shop who loves my car so we have experimented about every which way we can think of --- yes i still run the 1996 LT1 with every imagineable bolt on you can think of .. best power ? Long Tube Headers , dual Cats 3 " all the way out the tail ... i also tried open headers , great sound , great revs but 60 lbs less torque on the dyno , these engines rely on the back pressure to retain torque. Any one else with similar or dis-similar experiences ?


Chris
Transamman25@hotmail.com

I realize i am new so heres a little introduction , My name is Chris , ive owned 8 F-bodies everything from classic 70,77,78,79,80,87,93,and now my beloved 96 which i purchased after getting out of the Army (Infantry) this August. Before the Army i worked for the Chevrolet Dealership for three years , i look forward to fellow car nut fellowship and if there are any Memphis guys here id like an email - i want to start a real F-body club in Memphis anyone from here knows what i mean.

[five7kid]

It ain't the "backpressure", it's the pulse tuning of the collector.

Try again with collector extenders. 16-18" with long-tubes is pretty typical. Some engines will like longer, some shorter.

[Jaberwaki]

you didn't lose power , you moved it further up the rpm band, the lt1 does not rev high, so chances are you moved the power further up then you were spinning it.
the word "back pressure" are a bad way to describe what you are talking about.

[4348rd]

you didn't lose power , you moved it further up the rpm band, the lt1 does not rev high, so chances are you moved the power further up then you were spinning it.
the word "back pressure" are a bad way to describe what you are talking about.
exactly