Exhaust Systems - Theory

Dunno- any exhaust's power-enhancing capabilities needs to reference all the OTHER associated components to work better than stock. It would take a dyno to prove any advantage of one type of muffler over another, I suspect. Another thought-,how much noise can you & your local police tolerate? New noise requirements are due to be phased-in for 2004, according to some reports. As to your second & 3rd questions, all Pantera engines were pulled directly from Ford's assembly line with no extra work done. The Pantera engine plate carried the block number ID, but thats all- the engines were garden-variety. The stock engine red-line was dependent on the hydraulic lifters & single valve springs included; no known Boss-351 solid lifter engines were ever factory-installed. Note-the only finishing Pantera Gr-4 at the '72 LeMans 24-hr race ran one of these assembly-line engines after all the 'built- engines' were over-revved and destroyed.

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Originally posted by ron norman:
Do Big Bore Headers/Exhaust systems increase Horsepower (HP) at low RPM, hi RPM or both? What is the effect on the power band, broader, flatter, more torque at low RPM only? Does a 351-C require some back pressure to funcion better across the powerband? What HP increase can one expect for Big Bore Headers/Exhaust Systems? Should the exhaust system only be upgraded if the intake system is upgraded?

Lastly, were the 351-C engines supplied to the De Tomaso Factory balanced and blue printed or in any way given preference over 351-C engines going into Mustangs, Boss 302s, Mach 1s, etc? Is the Red-Line of a Pantera rated higher than those factory cars?

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This depends on your came timing, if you change your came timing (just a few degrees)and put an exhaust system with more flow on it, you can expect more power in the high rpm range, as well in the low rpm range whith wide open throttle.
Only in the low rpm range with almost closed throttle you loose some torque, and the car won't run as smooth as it did before.
If the intake is upgraded, the gain is even better, up to a certain point, if you want to cross this point, you'll have to invest some money in your engine.

Paul.

Thank you for your response. I am wondering if it would be worth it to just increase the diameter of the exhaust from the header collectors to the Ansa muffler. I gotta decide before I get Jet-Hot Coatings applied. I don't want to be really loud.

The header tubes, before the collectors, are about the same diameter as the 2' exhaust pipe going to the muffler.

How many times do the headers have to be re-tightened after removal, reinstallation?

I like the fact the factory 351-C finished the 24 Hours of Le Mans.

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Originally posted by ron norman:
Thank you for your response. I am wondering if it would be worth it to just increase the diameter of the exhaust from the header collectors to the Ansa muffler. I gotta decide before I get Jet-Hot Coatings applied. I don't want to be really loud.

The header tubes, before the collectors, are about the same diameter as the 2' exhaust pipe going to the muffler.

How many times do the headers have to be re-tightened after removal, reinstallation?

I like the fact the factory 351-C finished the 24 Hours of Le Mans.

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No, the power increase is very little (if there even is an increase) and I think it isen't worth the work you have to do to create this.
Whenever I re-install my exhaust, I retighten it 2 times.

Paul.

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A. Do Big Bore Headers/Exhaust systems increase Horsepower (HP)
B. at low RPM, hi RPM or both?
C. What is the effect on the power band, broader, flatter, more torque at low RPM only?
D. Does a 351-C require some back pressure to funcion better across the powerband? [/B]

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A. The Big Bore header by zise is fairly good. But the port matching is many times bad,and needs to be grind-out. The BB mufflers is restrictivee. So, a set of port matched big bore;s and a good muffler is OK.

B. A header has a diameter that creates exhaust speed, and a lenght that creates pulses. This makes the headers to work at a certain rpm.

C. What creates a broader powerband is the lay-out of the headers. So, here the big bore are the same as Pantera original system, a four in to one. Headers is tuned to give better volumetric efficency at the selected rpm. Which can be at max torque rpm, or max Hp rpm. That is up to the engine builder.

D. For the best volumetric efficency, no enging likes back pressure. Well, sometimes a two stroker.

Goran Malmberg.

Mr. Malmberg,

Thank you for your response. Thank you also for the article you wrote in the Spring 2003 issue of Pantera International.

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Originally posted by hemip:

A. The Big Bore header by zise is fairly good. But the port matching is many times bad,and needs to be grind-out. The BB mufflers is restrictivee. So, a set of port matched big bore;s and a good muffler is OK.

B. A header has a diameter that creates exhaust speed, and a lenght that creates pulses. This makes the headers to work at a certain rpm.

C. What creates a broader powerband is the lay-out of the headers. So, here the big bore are the same as Pantera original system, a four in to one. Headers is tuned to give better volumetric efficency at the selected rpm. Which can be at max torque rpm, or max Hp rpm. That is up to the engine builder.

D. For the best volumetric efficency, no enging likes back pressure. Well, sometimes a two stroker.

Goran Malmberg.

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As I am not the wealthiest man, and have many Pantera Projects I want to accomplish, I have had to prioritize them into my cash flow capabilities. Ultimately, they will all be accomplished, but, in order of cost/benfit analysis, may I ask a few more questions of you, please?

1.) Carburation:
Which carburator do you like best, or could you recommend for my application? I drive approximately 2/3 in the countryside, away from traffic, with half in turns and curves in the mountains and the other half on straight line freeways. In traffic, occassionally I accelerate hard, but normally do not achieve high RPMs, and only for short bursts. Maybe once a year a like to go top speed, flat out, again only for very short duration.
So, I'm thinking, maybe a 700 cfm, double pumper would do nicely. I have a stock engine, no modifications with 42,000 relatively easy miles, and no problems.
Do you like: (a) Holley. (Seems the choke never works on Holleys) (b) Carter. (c) Speed Demon. (d) Other type.
2.) Intake Manifold:
I'm told short, flat manifolds are better for Horsepower and taller, longer travel, high rise manifolds are better for torque. Is this an accurate understanding? Is it even worth it to change the standard manifold? Maybe later?
Do you think my driving style/needs would be better satisfied with an emphasis on Horsepower or Torque?
3.) Wheels:
(a) I am leaning toward Pantera East as a wheel/rim vendor, because (i) I like their looks the best and (ii) they have the 16x8" front and 17x11" rear available in the Campagnolo copy ("Campy clones") style. Is their version of this rim, say 'competitive' in the "weight" category? I doubt I'll have the opportunity to weigh each vendor's wheel/rim product.
4.) Which commercially available exhaust system do you like best? Do you have an idea what Horsepower or Torque advantage can approximately be expected, even in terms of relative percentages?

Thank you for your answers, knowledge and efforts. Perhaps many others may have wanted to know these answers to their same questions and not had such opportunity to be offered informed advice. Hopefully, many others may read our Posts on this Forum, and become a little happier with the knowledge they gained.

Ron Norman

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[This message has been edited by ron norman (edited 07-04-2003).]

[This message has been edited by ron norman (edited 07-04-2003).]

Thank you all for your replies, EVERYONE!

Please voice your opinions, expertise, and experience. Both 'Seat of the Pants' and PULL ON THE NECK opinion, expertise, and experience is encouraged, as well as theoretical knowledge. All was hard won and much appreciated.

I'm learning from Pantera Guys with more knowledge and experience than I have, that's for sure! And I crave the knowledge and appreciate the answers, insight and help.

It's amazing to get responses from Europeans, and makes me (us?) wonder, maybe there is a big, interested audience, beyond our belief..., so let's help them all out, now and in the future, when they may review this information in the 'Archives.' Thank you.

As far as tightening the header-to-exhaust pipe bolts, it depends on the gasket used, Due to the design of the muffler braket used, there is a force applied down the pipe to the header flange when you hit a bump. So in my experience, the thick dough-nut gaskets last very little time, resulting in loose bolts & leaks. A flat gasket can be substituted with no flange chanegs at all, and will not pound out, but may require you to true up the flanges if they've been severely bent over the last 32 years. I also double-nut all the flange bolts, first applying Anti-Sieze to the bolts.