And if you look at almost every new engine out there, they've put a lot of time into trying to improve the exhaust with better manifolds. The higher end exhaust systems on Vette's for example are pretty decent..yet headers always help significantly. The systems after the cats aren't bad at all and many see very little increase by changing them.

Long tubes from the factory made out of stainless for 100K mile warranties and/or coated for corrosion isn't practical plus the issues they have to deal with concerning NVH. They use manifolds because they are cheap to produce and hold heat so cat converters heat up super fast and light off when placed right up close to them.

Even some of the short tube factory headers are better than manifolds. My '88 5/0 Mustang has them...look funky as heck...but better than manifolds.

Long tube headers will help part throttle response and power also...but again....most gains are at WOT where you're filling the cylinders and have something to get out of them. Part throttle there isn't much in there in the first place.

Extra engine compartment heat? Well OK...but never had a problem with it. And if coated they are lots cooler than manifolds.

Not sure what your hang up is on stock mufflers. Not that many of us have stock mufflers..and if you do...it's either a rusted out stocker with less restriction probaly or a knock off replacement that is more restrictive than stock. We could go on and on with what type of muffler...baffled, chambered, straight through...because all of them act differently with respect to exhaust tuning and if you get crazy and real serious will affect cam choice also.

And again, who cares about "3500 RPM"? Part throttle cruising is just that...cruising. Tuning takes care of that. Yes..headers will enhance that and help fuel mileage. WOT will improve significantly...and THAT's why we modify things to add power. You won't get it until you stuff your foot in it...so it's moot right up until then.

If whatever power you have is enough...then leave the hood shut. But the fact is...this is the Tech/Performance section...and that's why people are here. What will give better performance and how do to do it. Yes that could be gas mileage improvement...or even your choke adventures......but whether it's worth it or not entirely depends on if you have the cajones to use it!

JIM

 

I don't need much convincing on the aspects of headers, but for my '73 BB, is there a particular brand of LT's that fit better than others? I want ceramic coated if at all possible.

 

I have ceramic Hedman LT:s on mine, perfect fit!

 

And lets not forget the intellect to apply it correctly. A good post 427.
I always love it when folks have an opinion on a subject with absolutely NO practical experience in it.
Don't get me wrong book learning is good, and necessary, but they got to get it in the right perspective.
The real world does not know that they are smarter than it is, and therefore may actually educate them, if they bother to pay attention.

 

I have often heard L-48 owners claim a 3 mpg increase after installing long tube headers. Figuring an average of 15 mpg before and an 18 mpg after that would be an astonishing 20% gain. If headers would actually increase the cruising mileage by 20% every car in the world would come equipped with long tube headers. But long tube headers won't provide a 20% increase which is why the factories have never installed them on any of their production cars.

Headers do have a definite advantage in track racing where rpms are kept high under wide open throttles but for street use where revs rarely exceed 3500 rpm and throttle openings are kept to a minimum I can't see any advantage to running headers. In my opinion 4 to 5 speed transmissions and lower rear gears play a much more important role in increased performance.

 

In my opinion headers are awesome.

In my experience and many others, including countless numbers of back to back testing, headers improve power everywhere.

 

Okey Dokey. Be prepared to be passed by the guy who did see it as an advantage. Again, the confusion of WOT power (like merging onto the highway or just having fun on a wide open stretch of highway going through the gears) vs. light throttle cruise. Don't think I've ever heard of anyone that didn't feel the power difference. Heck my 2.0 Pinto in high school woke up with headers and a different exhaust system! (lil sucker ran 14.60's back when folks thought a '77-'79 Trans Am,Z-28 or Vette were fast!),

3 MPG increase on an L-48? There could be 20 HP there at WOT easily....3 MPG increase....I wouldn't count on that either..especially with highway gears and low RPM of an O/D.

I've seen a 75+ HP loss with rams horns on a 500+ HP 406 combination that made peak power at 6300 RPM or so. On a 327/250HP...not so much.

This wasn't a fuel mileage discussion. This was about power. Me? I like to design an engine to make as much power as I possibly can given whatever limitations are required so that when I put my foot flat on the floor I get as much WOT performance as possible. The rest of the time when cruising around, I count on my tuning abilities to make it drive well under part throttle. The two aren't mutually exclusive.

But for folks who like to drive stock stuff and their idea of performance is to pass an NCRS "performance verification" where we make sure all the door handles are clocked properly and the turn signals blink at the proper time interval....well as Dirty Harry said..."A Man's got to know his limitations"!!

JIM

 

...and some people are still in search of their 'limitations'.

GREAT replies to this thread!

DUB

 

Those BlackJack headers were great headers. They didn't hang low either. Had mine for near 20 years and then sold them. Metal thickness was still like the day I bought them.

 

 

BlackJack did make some nice headers. I bought a couple of sets from JC Penny way back when!

JIM

 

Does anyone make an aftermarket Rams Head-style manifold that gives performance gains, while keeping the stock look?
Thanks

 

When the new Corvettes come off the assembly lines with long tube headers I'll hop on board. Until then I'll consider long tube headers to be a waste of money for street-driven cars.

 

Of course. Wouldn't want facts to influence your unfounded beliefs.

 

...now on my ignore list.

 

I love my Hedman headers.

 

DUB[/QUOTE]


DUB said "There is a limit to what I personally feel is usable for the street."

I agree completely. My 93 RX-7 has aftermarket turbos, computer, exhaust, intercooler and other mods that translate to 420 rwhp. Some of the youngsters in the rotary engine crowd try to get even more hp. Not sure why, since my car weighs only 2400 lbs, has a 4.10 rear axle and spins the rear wheels at 100 mph in third gear. Except for bragging rights, there is a point where more power just does not make you go any faster. Either the rear wheels spin in older cars without electronic traction control or the computer starts to throttle down so you do not go out of control and kill yourself. Most of the 500 plus hp new cars hardly ever run at full throttle if the traction control is on.

 

Just a quick look at C7 exhaust manifolds demonstrate what the OEM's are doing with lengthening tubes, but again,,,,there's packaging issues with Cats.

Whatever....But I'm curious why you have a 454, aluminum intake and a Holley on you street use Vette. None of that is needed for daily street use. Might as well drop an L-48 in it.

Or drive a Prius....

JIM

 

In this world of heavy traffic and speed zones and 2-lane roads its awfully hard to "open her up" like we could do in the 1960's. I concentrate on low end grunt to get me to point B and leave the high-winding antics to the younger folks who haven't learned speed kills.

 

Mine too.