I just got done installing FLowtech Longtubes the 3" ORY and TSP Rumbler cat-back with the muffler removed. My car is slower now when I just punch it from like 10 mph but after about 2500 rpm's it takes off like a ****. Is this normal for headers? Losing a little low RPM power but gaining way more upper RPM power? Also like when I punch it in 6th going down highway it is a little doggier there too.

I am not tuned either if that makes a diff, but is this common after longtubes installed?

 

I think LT's give a lot of low end power... Not sure why it would be slower down low...

 

Ive always heard that you do lose some tq down low with long tubes...but maybe Im just retarded.

Dang, your car must be LOUD. Headers, ORY and No Muffler.

 

You do loose low end torque, but gain upper end.

 

Therefore stock manifolds increase low end torque

 

I am not so sure you lose torque, it just moves up in the RPM band, I have never seen a before and after graph showing that Longtubes caused a lose of power anywhere in the curve.

 

Well I wonder if the major change in backpressure mabey. It just seems to not throw you back in the seat at lower rpm's right as quick but does after about 2500 and revs way quicker.

Headers, no cats, no muffler. Not terribly loud actually, Going down the highway I BARELY hear it and it isn't any louder than before I had headers until about 2K.

 

I dont think so pal.... Show me a dyno sheet, then I will believe you... Until then...

 

it just feels like you lost down low. give it a week or two and you'll get used to the power and wont feel like the bottom end is soggier. i used to have a before/after dyno of a hooker LT install but i dont know what i did with it . i saved it specifically to point out that at no point in the powerband are you loosing power over stock.

 

I think what JRP makes the most sense. Cause I guess it doesn't feel much more sluggish just that as the RPM's go up it takes off so much more then that it makes the lower seem slower.

 

I am not sure whose dynos show accurate dyno figures
off idle? Most dynos I have seen start to show good readings
above 2500rpm etc.

Gert

 

Don't worry about it man, I just recently experienced the same thing after I installed some Kooks LT's w/ cats on my LS1 in addition to the lid and cat-back I already had. When you punch it down low or at low speeds, it doesn't feel as "torquey," but once it reaches the mid rpms, it just pulls so hard all the way to redline...

Mike

 

Good, that is exactly what I wanted to hear. I am not the only one who notices and thats what I feel exactly.

 

every day for a week my car felt stronger after installing macs and cutouts(with no tune,obviously)........and it gets quiter too.....oh, wait, i think maybe i'm just going deaf...

 

WHAT?

 

Gotta watch that SOTP dyno... ;-) Do you have a dyno sheet for before and after? I'm with JRP on this one.

 

I'd say the main reason you lost some bottom end was removing the muffler.. I wouldn't say the longtubes were the culprit. A little backpressure will help with the off throttle torque

 

Would a Dynomax Bullet really make that much mroe backpressure than a staight pipe in place of it? They are pretty free flowing.

 

It,a known fact headers scavenge thats why we use them,the more back pressure you lose the more low down torque you lose.
None or open mufflers, long tube 4 into 1 work extremely well hence lack of low torque.

 

I thought we debunked the "backpressure is good" theory and established that back pressure never helps - at any RPMs.