Back Pressure - Myth or Fact?

[robtek]

Hey guys,

The first modification to my exhaust system, was all 3 mufflers removed..and 3 big hotdogs put into their places...the sound was VERY, VERY deep but ended up blowing out my cat:P...was crap low end, but high end was good,(this was done prior to any other mods;))..then due to insurance purposes...I had the extractors and 2.5inch system fitted with highflow cat...only one straight through muffler exists...but it is no where near as fat or deep...

Q: 50% of places/mechanics/wreckers/others told me back pressure is a myth and mufflers are only their to damp the noise..

Other 50% of places told me without back pressure im going to do major damage to my engine, and performance will be shithouse, unless I am on a circular race track :P...which is true?...ive done abit of research but the arguemnt still sways 50/50 ...anyone can relate or answer with a personal example??

I just want that DEEP fat noise back:(..not sure if i should waste $$ for a couple more hotdogs..

Thanks guys

Big Rob

[feebs]

By your sig.. I assume your engine is MPEFI.. which means it can adjust the air fuel mix to make up for any change in exhaust flow.

So not an issue.. as long as the o2 sensor is functioning.


As far as the note goes.. you just have to keep experimenting.

I think one high flow muffler.. with one resinator or hot dog at the rear.

[blur1]

ask yourself this question.. do drag cars have full exhausts fitted?

[LTDHO]

Originally Posted by blur1

ask yourself this question.. do drag cars have full exhausts fitted?

Exactly. They are designed for high rpm revving.

I believe the back presuure helps the scavaging of the exhaust, which helps low down power.

[robtek]

Originally Posted by blur1

ask yourself this question.. do drag cars have full exhausts fitted?

hi blur...no i dont have a drag car, nor do i want to fork out another $10K to turn mine into one...im simply asking if BACK PRESSURE with regards to exhaust systems is FACT or FICTION ...

Big Rob

[blur1]

fiction, it wont hurt your engine. it might not be tuned to take advantage of no back pressure, but it wont hurt it.

[robtek]

Originally Posted by blur1

fiction, it wont hurt your engine. it might not be tuned to take advantage of no back pressure, but it wont hurt it.

yeh true, tuning would play a big part

[wanabelowner]

well all i can say .. yes their is difference with no back pressure .. u would want a some amount of it .. i guess it would come down to alot of things .. and to compare a drag car to a streeter . u cant .. their is like couisens not brothers .. different fuels .. and alot of them are supercharged .. S/S cars .. most have Massive cams and alot run race fuels .. or Av/gas .. and on the other had think about all them lil gemini's or commodore.. in around town .. that make alot of noise and go no where .. .. and one last thing .. ever had a car with a hole in the exhaust .. like 99% of the time .. it has lost power .. and u get it fixed .. and it goes soo much better ... i be puttin my money on that their has been a slight rise in back pressure .. and it normally is the lower to mid of your rev range ..

[blur1]

the question related more to 'will it hurt' my engine?....and the short answer is still no. :

[Gohan]

back pressure would make a diff if it was Turbocharged car its case of too much of a good thing its fine having 3 inch zorst from the turbo back then in2 4 inch that would have alot of backpressure on changing gears.

on an N/A engine there would be a lil gain in power or robbed of power? i have heard a BMW 3 coupe without resos and dont know how big he went sounded like a Lawnmower on roids and he got EPA'd for it

I'n my magna I dropped the exhaust at willowbank last time i was there, went from 2.1 60ft times to 2.3 60ft times as it had nothing in the low RPM's

[Nikked]

Back presure isa fact, always aim to have no more pressure in the exaust then in the intake, Back pressure robs horse power...

.. after all, why do race cars prefer free flowing mufflers/exaust's?