Backpressure?

[christianchevell]

Increasing the flow of the exhaust is simple hot rodding knowledge, he does not think in terms of your engine but rather in the old school of his knowledge of BBC vs SBC most likely and iron engines were my choice for building for cheap in many hot rodded chevys I built over the years, never was headers not a primary and immediate mod along with dropping in a better cam ,a better Edelbrock intake ,and Edelbrock or Holley carb along with a HEI ignition done it many times. But its a LS engine with heads that out flow easy the BBC heads he may think of and a 376 cu in aluminum engine with the tuning to be done the results are even better as the shape of the headers magnifies the torque a little and various manufacturers sell stepped headers or tri Y's etc for the exact reason that the effects for a few HP say with a merge spike versus just low end headers and none..... My dad; god rest his soul, would not go for a ride in my Chevelle ss with me..LOL I love the handling of the Camaro versus a old solid axle rear end......

You young whipper snappers and your high falutin ideas about making more power, sure It would be nice if you had a built engine first and install everything at once but hey money does not grow on trees!....he would be more used to buying a entire engine for what you would have to pay for heads... Headers now a days also can have high flow cats added and be very effective in design and greatly aid in the scavenging of the cylinders, so the old guy may get sticker shock if you tell him its about 4 grand for cam with the extras a install and dyno tune.......or you can drop $500 for a good CAI......

SO you may want to take it to the airwaves before giving dad too much information he is obviously thinking in Bizzaro terms a alternate universe for a good old chevy you can buy restoration parts for from places like classic industries etc and versus a new internally balanced aluminum engine that has coils on every spark plug, high flow heads, low back pressure is not a problem to even think of ; proven millions of times and even stock tune can sometimes handle headers if the CATs have been tuned out in the rear and the delayed response of the fronts ignored in the tune. This exhaust is not going to have back pressure problems and it really is more a myth the back pressure people usually allude to being able to negatively affect performance in various engines and exhaust combos. BECAUSE exhaust manufacturers know what sizes to make by experimenting and experience when making and shaping headers to keep the exhaust velocity up there and not bog from having no exhaust velocity......

How did the myth about back pressure and big pipes come to be?
I believe it is/was a misunderstanding of what is going on with the exhaust stream as pipe diameters change. For instance, someone with a Honda Civic decides he's going to upgrade his exhaust with a 3" diameter piping. Once it's installed the owner notices that he seems to have lost a good bit of power throughout the power band. He makes the connections in the following manner: "My wider exhaust eliminated all back pressure but I lost power, therefore the motor must need some back pressure in order to make power." What he did not realize is that he killed off all his flow velocity by using such a ridiculously wide pipe. It would have been possible for him to achieve close to zero back pressure with a much narrower pipe - in that way he would not have lost all his flow velocity.

http://www.gomog.com/allmorgan/exhaustbackpressure.html

Good Luck and go with headers!!!!! from someone elses DAD......LOL hell I am a grandpa long ago, dang I could be a great grandpa any time now crap. The difference for tuning for a 160 thermostat, eliminating the annoying torque management and even just a scanner like SCT tune would wake the Beast up, and prove to dad your doing fine when it sounds more like it should. And get high flows for the effects to be legal and cut the fuel smell and some rasp..Thats my advice if your going for it....heck even a ported TB is $150 just to port yours....a carb in the day...$150 new And there you go...

[Mr. Stacy]

These days the whole back-pressure thing kind of works like this. Think of the bull as the Camaro.

[Gunmetal Speedster]

Originally Posted by Mr. Stacy

These days the whole back-pressure thing kind of works like this. Think of the bull as the Camaro.

This is the best thing I've ever seen on this forum

[Iron Lung Jimmy]

Originally Posted by MrChrisLS3

Your dad isn't completely wrong. He's just got the terminology incorrect. what he's talking about that increases torque and thus power are the concepts of scavenging and vacuum pulse tuning.

The first two sentences in this video are awesome!

[JLSuperfly]

Originally Posted by Iron Lung Jimmy

The first two sentences in this video are awesome!

I am going to make my wife watch this. Blowing is important too. LOL.

[Moto-Mojo]

This thread has been informative on a number of levels. Especially the one where I didn't have to redirect to a porno site!

[jcaligood]

Great response C5, I appreciate it. Especially Christianchevell and JerTM.
Looks like i'll pull the trigger on LTH within a month or so.
Thanks again

[Rocky1974]

Originally Posted by jcaligood

I've been planning on ordering some long tube headers for a while, been comparing different brands and prices. I really like Speed Engineering headers.

I've been talking to my father about my plans, He's built 3 '68-'70 Chevelle's and many other GM vehicles, mainly older.

He says long tube headers are not worth it, because they reduce the backpressure in your exhaust system, which is responsible for your low end RPM HP.

He says i shouldn't buy headers until i've worked on the bottom end more, because I will lose power with headers.

How true is this? I know he knows what he is talking about. But... are headers not worth the money because they reduce backpressure in the exhaust? How important is this?

I respect my father a lot, please don't flame. Any decent feedback on this would be really appreciated.

Thanks C5!

With all due respect, your father couldn't be more wrong. What he says is not even correct about the old school stuff. They loved headers too. An engine is basically an air pump. Anything that helps air flow into or out of the engine, will help it make more power. The trick is always figuring out what the restrictions are. In this car, as in most modern cars, the biggest restriction are the air intake that was engineered more for noise reduction than air flow and the exhaust manifolds that were engineered more for emissions reductions than air flow. One of the reasons that headers are so effective on these engines is that the cylinder heads are so damn good. The heads are so good that they make the exhaust manifolds a major restriction.

Trust me, if you put a good set of long tubes on a LS3, get a good cold air intake and get a Dyno tune, it will feel like a whole different car, when you open it up. Then, if still you want more, get a cam.

The only concern I have, is that I see you live in California and I'm not sure that you will be able to pass emissions with long tubes, even if you put cats back on it. Maybe someone who has more experience wih California emissions can chime in on that.

[jcaligood]

Rocky, im pretty convinced headers give a huge HP gain. My fathers argument was loss of backpressure causes loss of low-end torque. but i guess i can just downshift if that was the case.
And for California, I'm active duty military and register my car in Florida, so im exempt from that smog test crap.
Thanks for the detaied response everyone. Now i just have to decide if i should buy speed engineering headers, or just spend a little more for some quality. From what ive read, speed engineering is great.

[Rocky1974]

Originally Posted by jcaligood

Rocky, im pretty convinced headers give a huge HP gain. My fathers argument was loss of backpressure causes loss of low-end torque. but i guess i can just downshift if that was the case.
And for California, I'm active duty military and register my car in Florida, so im exempt from that smog test crap.
Thanks for the detaied response everyone. Now i just have to decide if i should buy speed engineering headers, or just spend a little more for some quality. From what ive read, speed engineering is great.

But even that part is not correct either. Long tube headers are famous for their torque production. The long tubes hep the low end torque and the large tubes help top end power. The end result is more power everywhere.

If you're not subject to emissions, you can save yourself some money by not buying cats. I can't say anything about Speed Engineering headers because I've never even seen at set. They weren't available when I bought mine. I can't say anything about any of the others either, except Kooks. That's what I have. They are expensive, but they are nice! They fit like a glove. You just bolt them on and you'll forget they're there until you hit the throttle. I did buy the Kooks cats to go with my headers because I didn't want to deal with the odors that some people claim that they get when they go catless. At first I just hooked mine up to my stock catback and that worked well and sounded better than stock. Later I swapped it to a NPP setup and that sounds really sweet! Good luck with your mods!

[High Magnitude]

Hes talking about a muffler delete

[MrChrisLS3]

http://www.epi-eng.com/piston_engine...technology.htm

Interesting read on the subject of pulse tuning and different applications.

[frankwjr]

How you gonna beat the emissions test in Cali? Swap back and forth?

[JLSuperfly]

Originally Posted by frankwjr

How you gonna beat the emissions test in Cali? Swap back and forth?

Some members here from California stated that they know someone who knows someone that will pass their car regardless.

I don't know anyone.