Question about back pressure in my truck

[Adrenalinerush]

i've got alfomaster on my truck and i want it to be a little bit of a deeper tone so i'm going to just run a straight pipe from the cat back. what will that do to my truck. i know that i won't have a lot of back pressure. how long can i run it like that or will it not matter? will it not affect it or what. if anyone can help me i would be great ful:confused:

[allmixedup047]

it will be fine. i had flowmaster on my old truck and it was cut off right after the muffler. it makes it louder. i never had a problem nor did i notice a change in gass mileage.

[hondarider2006]

I run my blazer 350 straight piped right after the cat. Haven't made it come all the way out the rear, but for now sticking about 6" past the cat will work:devil:

[TRXRacer1]

Running a strait pipe from your cat will cause premature failure. Your cat works off of heat and when you strait pipe it from the cat it gets hotter then it is designed for and burns up the internals quicker. So if you tough emissions in your area I'd just be careful.

[bulkdriverlp]

i have a truck in my sig and the muffler shop told me he would put a y in after the cat and just run straight pipes out the back, it wont be to loud. id get a couple of opinions from proffessional muffler shops thou.

[fastmofo]

I had a 87 silverado w/ a 305. had duals with a turbo muffler and was way to quiet! cut the muffler off and put a y pipe in, drove it for 4 months tell i sold it, and the person who bought it still drives it like that. i wouldnt worry

now my buddy had a dodge ram with a carbed 318, ran straight duals off the manifold, when he would load it up, and romp on it, it would back fire and it would shoot flames out the tailpipes. needless to say he burnt up a few valves like 3 weeks later

[SGA]

Ive never heard of any problems from running straight pipes after the cat.
What year truck are we talking about anyway?

[Quad18star]

We used to run straight pipe from the headers back on a few cars we owned . Not a single problem . A little loud though :devil:

[440exnacsracer]

i have true dual exhaust on my 01 f150 (5.4 L) w/o mufflers and i have turndowns about 2 1/2 feet after my cats,..no problem at all, just a little worse gas milage and best of all , more power

[400exrules]

when u have straight pipes do u run it from cat converter straight out to dual exhaust pipes? without a muffler?

[Stevie-D]

when u have straight pipes do u run it from cat converter straight out to dual exhaust pipes? without a muffler?

yessir. or, you can put straight pipes on it with glasspacked stainless muffler tips(Heartthrob makes a kit) to get it to pass inspection, then remove muffler tips and replace with a set of stainless tips. or if your cheap, just go without tips. :blah:

[speedy400]

I ran nothing after my cat (which I ended up putting a 1 1/2 inch hole right down the middle) ran just peachy, little worse gasmilage and little less low end when had it with the hole and nothing, later on I put on a flowmaster 40, it runs awesome, so I basically have no cat, its a 1990 s-10 4.3 4by4, it makes 18.5mpg. And it spins the rubber very well.-darren

[hondarider2006]

Originally posted by speedy400
I ran nothing after my cat (which I ended up putting a 1 1/2 inch hole right down the middle) ran just peachy, little worse gasmilage and little less low end when had it with the hole and nothing, later on I put on a flowmaster 40, it runs awesome, so I basically have no cat, its a 1990 s-10 4.3 4by4, it makes 18.5mpg. And it spins the rubber very well.-darren


Does it still pass IM without the cat?:huh

[speedy400]

haha, I doubt it, but here in the little town no one cares! I've got buddies with straight dual exhaust, btw, remember you can get some backpressure by making the diameter get smaller., the buddies with the straight dual all the way back have smaller tubing so it works out well, say if he had 5 inch dual, his valves would be gone in no time, Dont quote me on this though, I'm no expert.-darren

[440exnacsracer]

best performing way to do duals is get true duals though, with two cats. i have true duals from my motor back with 2 cats and turndowns.

[LazeR]

Heres a link to read about back pressure

http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm

I believed in the myth that you needed backpressure or you could damage your engine, but if you provide, or your fuel injection or carbuerator provides enough fuel, it will not hurt it. You do not need backpressure as long as you have enough fuel in supply so that you do not run lean

[hondarider2006]

Originally posted by LazeR
Heres a link to read about back pressure

http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm

I believed in the myth that you needed backpressure or you could damage your engine, but if you provide, or your fuel injection or carbuerator provides enough fuel, it will not hurt it. You do not need backpressure as long as you have enough fuel in supply so that you do not run lean

So if you wanted to run a 400ex open header...lets say for a dragster, as long as you had it jetted properly, you could run it open header without burning up your motor?

[exrider360]

just do it rusty

[LazeR]

Originally posted by hondarider2006
So if you wanted to run a 400ex open header...lets say for a dragster, as long as you had it jetted properly, you could run it open header without burning up your motor?


Yea, as long as its not lean you should be fine. Or at least thats how i understood that article

[speedy400]

I really believe if you dont have any backpressure your motor will go very prematurly. I've been told by pros its hell on your rings and esp. valves, dont ask me to explain because I dont know, I just hear of people with EFI trucks and such dropping valves soon after they straight pipe it with not enough backpressure.-darren

[allmixedup047]

Originally posted by speedy400
I really believe if you dont have any backpressure your motor will go very prematurly. I've been told by pros its hell on your rings and esp. valves, dont ask me to explain because I dont know, I just hear of people with EFI trucks and such dropping valves soon after they straight pipe it with not enough backpressure.-darren
ive never had a problem with going prematurly.:macho :blah:

[speedy400]

Originally posted by allmixedup047
ive never had a problem with going prematurly.:macho :blah:
lol....:rolleyes: .-darren


-worthless post

[speedy400]

Alright, I looked this stuff up, I got intrested- the reason no backpressure is bad- because there is a point when bolth valves are open just a tad and if the air is moving too fast(no backpressure) it'll wanna go right out the exhaust, that little part when the cold air/gas is hitting the VERY hott exhaust valve, snap,crackle, POP, your exhaust valve just dropped...
:) -darren