exhaust back pressure truth or myth

Well dont know for sure but when I installed my Pypes Violators it just didnt have that WOW factor anymore. Some say it was in my head others say it was lack of back pressure. I was 90% sure it wasnt in my head. Installed stock mufflers today and got that WOW back.

Called brenspeed and Tillmans and they both said a revised tune wouldnt help with back pressure.

you think i dont have enough backpressure on my sixer with straight pipes and GTA mufflers?

I think its mostly myth... I really don't see why back pressure would help with anything at all.

I would guess the sooner you get the exhaust out the better... :headscratch:

EDIT:

I'm pretty sure I win. http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm

Preston951 said:

I think its mostly myth... I really don't see why back pressure would help with anything at all.

I would guess the sooner you get the exhaust out the better... :headscratch:

EDIT:

I'm pretty sure I win. The truth about exhaust backpressure and torque

Click to expand...

from what I understand from your link the tl;dr is that only older carb engines need back pressure so that the a/f ratio will be correct to keep from burning valves but because of the computer systems that are in new cars such as ours will adjust to keep the a/f ratio correct.

if the source is accurate then back pressure is not a myth but irrelevant in the case of none carbureted cars.

texanwitharake said:

from what I understand from your link the tl;dr is that only older carb engines need back pressure so that the a/f ratio will be correct to keep from burning valves but because of the computer systems that are in new cars such as ours will adjust to keep the a/f ratio correct.

if the source is accurate then back pressure is not a myth but irrelevant in the case of none carbureted cars.

Click to expand...

Yeah, what you said is true to an extent I believe.

I think that you'd need an appropriate tune with less backpressure... The Mustang's ECU can only adapt so much. BMWs are much smarter than our 'Stangs... :hihi:

you have to be carefully about back pressure, because if you don't have enough, you can crack a part while running "lean". at least thats what a mechanic told me.

a buddy of mine called me and talked to me about this topic today. he races his DD almost ever wednesday at the local track by me. He's run borla stingers and simple bolt on mods for the longest time, car has over 100k. he told me the other day he ripped off his borla stingers, and threw on the stock mufflers and gained 2 tenths of a second off his 1/4 mile time???.

i was thinkin to myself, is that possible, or perhaps its in his head and maybe that day he was just having a good day at the track. i dont get it....

I had a 95 camaro(bad word I know) that I put 3" dual exhaust on along with headers and my low end suffered quit a bit. The mid and topend improved though. I should have stayed with 2 1/2" exhaust.

Preston951 said:

I think its mostly myth... I really don't see why back pressure would help with anything at all.

I would guess the sooner you get the exhaust out the better... :headscratch:

EDIT:

I'm pretty sure I win. The truth about exhaust backpressure and torque

Click to expand...

thats the same site i read and i think its a myth as well but sometimes i have my doubts

I am a little confused....heres why. When I put the axel-back Pypes on I noticed weaker acceleration. So after 2 weeks decided to put stocks back on and it was still just as weak. So I recaled the pedal possition. (5 second in 5 second off on the pedal thing). Got good acceleration again. I wish I could remember if I did a recal with the Pypes on but I dont.

Father put new mufflers on his fat boy and had to have a new chip installed to account for lack of back pressure.

When i put my SLP loudmouths on my GT i noticed a lack of power on the get go. Got my SCT tune from brenspeed the next day and it was gone.

I'm no mechanic but i have to assume there is something going on with the back pressure or something in general. Get a tune. Even if it doesn't fix the problem it sure as makes the car that much more fun to drive in general if thats not reason enough to get one.

With proper tuning, less back pressure will always make more power. That's why racecars are loud. That doesn't mean go unbolt your manifolds. The misconception is that less exhaust equals less back pressure, but in reality, a properly designed exhaust will actually scavenge or suck the burned gases from the combustion chamber. With no exhaust, there is nothing holding them there, but nothing pulling them out either.

I am not sure about our cars and their computers' ability to compensate for an open exhaust. What I do know is that back in the day if we wanted to change a full exhaust and restricted air cleaner to drag pipes and high flow air filter on an HD, we had to re-jet the carb so the bike did not run lean (or run like crap). On the new fuel injected HD's you still have to have the computer re- mapped when making these changes.

tornthorn said:

I am a little confused....heres why. When I put the axel-back Pypes on I noticed weaker acceleration. So after 2 weeks decided to put stocks back on and it was still just as weak. So I recaled the pedal possition. (5 second in 5 second off on the pedal thing). Got good acceleration again. I wish I could remember if I did a recal with the Pypes on but I dont.

Click to expand...

What is this recaling of the pedal position and is it something that needs to be done often?