^^^^yes that theroy applys when you have a built to the hills engine not one designed to run with backpressure. Every s-10 blazer was built to run with backpressure i dont care what is said about it. If it was meant to be like that the enginers would have put side exits on everything, they didnt do it for reasons and that reason would be backpressure

 

blazerboyz, I guess you are just too mixed up in the debate to step back and look at the information posted... Blinded to it perhaps.

An engine is a glorified air pump. That is all that it is. If you can more efficiently get air in and out of the engine, it will benefit. Back pressure is caused by restriction which reduces efficiency. Factory exhaust systems are built on the cheap with cost being the #1 priority, regulations compliance #2, and performance a distant #3 on vehicles like this. Sure, the engineer's do the best they can with the requirements they are given, but there are definite areas that can be improved upon.

 

I'd like to know how you came up with that idea, because whoever told you that backpressure is needed to make an engine run more efficiently needs to be kicked in the teeth because that's simply not true, any engine builder worth his salt can tell you that. Like already stated, factory exhaust is meant to be cheap, quiet and legal. Side exits I don't believe are legal now on anything except pickups as long as they exit behind the cab, beyond that it's not.

 

I'm no genius, but from what i understand; backpressure is needed if you're running pipes too big, for instance, if you run the stock 2.5" pipes on the s10s with a stock motor then the engineers planned on the backpressure and you would need some backpressure, now if you went down to maybe 2.25" pipes you may not need backpressure, my dad's '66 c10 makes sick power and has 2-7/8" pipes with 2 90* bends and mufflers, yet another '66 in the area makes slightly less with 3" pipes with side exit exhaust and better high flow mufflers, my dads also has an h-pipe, the other an x-pipe. now my '92 has no cat at the moment and seems to need the lack of backpressure to run right, but again, i'm no genius.

 

Back pressure is a MYTH. Plain and simple.

You can hardly compare two vehicles solely on their exhaust unless they are both identical in EVERY other way. FAR too many factors are at play for such a comparison to have any weight.

 

If the pipes are too big then they're too big, backpressure won't help. Maybe a bend in the exhaust that's crush bent may help since the pipe size decreases and the smaller pipe helps to speed up the exhaust flow, but that doesn't mean it needs backpressure, just means your pipe size is incorrect.

 

Ok then kyle, if you believe in this so much!!!! Where is your exhaust located?? And would you do this to your rainer?? Im thinkin no but you tell me truthfully and i will stop!?

 

I'm calling troll on blazerboyz. Either he's purposefully playing dumb at this point or he hasn't finished high school physics. They still teach physics in high schools, right? I want to have some hope for this generation.

The best exhaust is one that is large enough to let the exhaust flow freely and one that introduces as little turbulence into the flow as possible while venting it to the outside of the vehicle. For maximum power, you want a big pipe (although there are diminishing returns with increasing pipe size) with as few bends as possible.

What travisrussel88 says about having the perfect sized pipe is true, although for the purpose of reducing back pressure, not increasing it. You want to minimize where pockets of low pressure can form and cause turbulence that will slow down overall flow. Unless, of course, you're running pipes straight out from the headers with essentially no bends like most drag engines do... then bigger is better.

 

The exhaust on my Rainier is stock and will remain that way until it rots off. About the only thing that I may do is remove the resonator at the back to get a bit more tone out of it, but it will still exit at the back of the vehicle due to NYS regulations which REQUIRE the exhaust to exit beyond the passenger compartment to limit the possibility of exhaust gasses reentering the cabin.

My K5 has the exhaust dumping directly ahead of the rear axle which technically is not in complete compliance with the laws, but due to its age, nothing in that regard gets looked at. Before I am all said and done, it will exit out behind the rear tires. But that is a true dual 2.5" mandrel bent system that flows WAY better than the original system by a hefty margin.

As I said here and as a response to the rather rude PM you sent me, no where in this thread or any others have I said anything in regards to dumps in front of the tires. Go back and read through it all again. I'm not sure you will ever take those blinders off... This 'for me or against me' attitude has to go. It is quite clear that debating anything is not your strong suit as you so quickly result to lies and innuendo.

 

only if you're gonna be driving an old diesel Chevette, you ain't gonna see no 50 mpg in any TD truck.


ok Vic, couple of things, since you seem to be nit-picking a fight with me over words..................

where did i say that becasue of the issue Ford had on their '97 F150's, that all side exhausts were bad? what's that?........right-NOWHERE! it is a false statement-'cause that's not what i said.


and you're comparing apples to oranges brother.........and changing the facts of your statement.

first you say you were running a highflow cat & a Magnaflow for over 10 years-but in the next breath, you state you only recently put on a cat. so which is it? proper-yet tuned-system for the last 10 years, or a set up like i had?

doesn't matter, it still apples to oranges. why is that, you say? well..........i'm sure you didn't have no 4.3 in your truck while you were towing that gooseneck behind it, and we all know that a V8 (the 350/5.7, is that what was in your tow rig?) is a better design than the 4.3. but it sounds like we both drove our trucks just as hard.

now..........since i never owned the truck from day one, i can't say how it was treated, but it was all highway (saleman owned it, & it had 173,000kms/107,500miles when i bought it when it was 4 years old), it did cook the top end around the 330 mark (which would be around 205,000 miles). i'm sure you didn't pull that trailer daily, but my Jimmy did see the abuse daily. not making excusses, just giving you better info on the conditions it lived in. in reality........4 to 5 grand launches in 4HI, and 7 grand shifts is not a healthy enviroment for anything that is not well built.


now back to the issue @ hand.....................

"backpressure".........such a poorly used word (by many of us). while the proper term is indeed "scavenging", you can not deny that improper scavenging works like backpressure. if the pipes are to small, they restrict the exhaust flow, thereby creating backpressure. if they're too large, they don't create the correct amount of flow throughout the exhaust system.

having said that, you can see how a vast majority of people believe that an engine requires it. and the statement that any modern EFI engine can run on an open header-regardless of any current noise/pollution laws-without any issues, is a load of horse manure. we all know that the "brains" behind the engine management in our trucks throw a fit when it doesn't read any proper 02 readings, so how can it be said that it can run on open exhaust?

but on the performance side of the arguement...........it's is a gain. i don't remember who it was that mentioned the old crayon trick, but they're right....i've had many old hot rodders tell me that's how they used to do it. but again, size does play into the gains. i had 3" "shorty" duels on my built '81, but had no bottom end. changed them to 2 1/2", and the truck performed waaaaaay better.


and lastly.............Vic......@ least you had nice 'n tastfull side dumps........unlike this guy......



(^^^ gotta luv the chrome handles, eh?)