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Explain 3" exhaust system advantage.

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Racer57

Racer57

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You know how retahded this sounds, don't you? A 1970 Hemi barracuda made 426 horsepower, trapped 107 mph in the quarter mile and weighed, what... 3300 lbs?


A 2018 Mustang GT makes 460 horsepower, weighs several hundred pounds MORE than the Hemi car, and traps 112-115mph more regularly than a 0700 bowel movement.

I can promise you, the tiny 302 moves more air.
Nice to see the intelligence level of some posts. Comparing trap speeds from 53 years ago ?
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furdfan2018

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In the air compressor industry HP and CFM are directly proportional.
An internal combustion reciprocating piston engine has far too many variables for HP and CFM to be directly proportional and constant.
Yeah, but it's pretty damn close.

It's the reason you can get a darn close idea of how much HP youre making based on lb/min reading of a properly calibrated MAF sensor.

It's also the reason you will never (EVER) on any engine size/cylinder count/compression ratio you can think of -- get a turbocharger rated at 200 HP to produce 600hp. There will be anomoles and some anecdotes of overachievers, but when talking about the "rule" and the "exception" -- the math is what it is and you cannot change it.
 

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Nice to see the intelligence level of some posts. Comparing trap speeds from 53 years ago ?
Trap speed is a DIRECT indication of wheel horsepower, sharpie.

Wake up.
 

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Nice, are you a member of a team?
 

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furdfan2018

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Resorting to name calling ? Just how old are you ? Tires, tranny, chassis are vastly different now than 53 years ago.
Not old enough apparently to miss the reason why/how in 2023 a smaller engine cannot move more air than a mighty Hemi.

Tranny/chassis/tires have far less to do with it than you think.

The fact is, in a straight line race a 2014+ modern Mustang GT lays waste to a 1970 hemi cuda 10/10 times and then 2x on Sunday.
 

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Ever seen the headers on a 900hp Indycar or 1,500hp Pro Stock ?
How about a set of Calvin Elston’s 4-2-1 Winston Cup restrictor plate headers or his Outlaw 4-2-1’s
Calvin’s 2V header dynamics at its finest.
 
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K4fxd

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When I worked at Mazak they brought their sponsored Indy car into the Florence Ky factory for some kind of shin ding. We got to inspect it real close. We also set up a multi tool CNC machine that fully machined engine blocks. It was cool watching it work on the test blocks.

This was before cell phones and camera's were not allowed.
 

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Hello; Been following this thread. I know the traditional views on exhaust but cannot say i have ever been able to test any. I have saved 84 episodes of Engine Masters however. I watched episode seven(7) of seasonfive(5). titled single vs. dual exhaust.
In the episode they run a 351 ford on a dyno. They use shorty headers. The setup is many folds.

First First they run a dual exhaust with 2 1/2 inch pipe. On the dual exhaust setup they run turbo mufflers and later a straight thru mufflers (see thru muffler.) The first run is with turbo mufflers an 2 1/2 pipes. No H nor X pipe. Run yielded torque of 405.3 @ 4100 rpm & HP 414.7 @ 6400 rpm.

Next set up is with straight thru mufflers. Same everything else. Still 2 1/2 pipes. Yielded torque of 412.8 @4200 rpm & HP of 420.5 @ 6200 rpm. Significant gain in torque between 300o to 3500 rpm. Maybe 30 ft-lb at 3000 to 3200 rpm the some lesser gain thru the rest of the rpm range. Similar for HP with maybe 25 HP gain in lower rpm range but some more all the way.

Next is a single exhaust with three (3) inch pipes. Two configurations. First has the two banks of the engine meeting at 90 degrees into the single pipe with a 3 inch turbo muffler. Yield was torque of 398. 9 @ 4000 rpm & 374.1 HP at 6300 rpm. A significant loss everywhere on the curves and the biggest loss at higher RPM's. Note - also changed the fuel mix to rich.

Next, they change the merge into a Y type. With turbo muffler yielded torque of 397.2 @ 3900 rpm & 383.5 HP @ 6200 rpm. not much difference over all but decent torque and HP gain in low RPMs to about 3800 rpm. Hardly any difference at higher rpms.

Last setup single 3 inch with Y merge and straight thru mufflers. Yield torque 422.9 @ 4000 rpm & 424.5 @ 6300 rpm. best peak overall of all setups. Thru the entire RPM curve significantly beat the 2 1/2 dual exhaust with straight thru mufflers everywhere except at high RPMs. maybe 25 ft pounds of more torque from 3000 to around 4200 rpm. Maybe 10 HP in that same range.

Again no H nor X pipe. I have watched all the 84 episodes of these dyno runs. What I glean from that is there are too many variables to make generalized statements for all engines. Change the heads or cam or headers and results might be different.
About the only thing that stands out is the straight thru muffler is a winner in this setup. Also, in a single exhaust having a Y pipe type merge works better.

I admit i was not expecting a single exhaust setup to beat any dual exhaust. Freiberger also thinks that the engine making less than 400 HP might be a factor.
 

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Also, in a single exhaust having a Y pipe type merge works better.

I admit i was not expecting a single exhaust setup to beat any dual exhaust.
This is not surprising for Full length systems.
The big singles on a V8 just sound funky
 

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I'm all about fuel economy, so I went with a custom dual 1in setup. When I plug in my FuelShark, it's on.....






























Seriously tho, exhaust should be sized according to application. Give the engine what it wants. Stock? 1500HP? Just putt around? Race? Different needs, different sized exhaust. Coyotes have a huge operating range and compromise is assumed.
 

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This is not surprising for Full length systems.
The big singles on a V8 just sound funky
Hello; The exhaust on my pickup in a single. I have a V8. I plan to get a nicer sounding replacement someday. Thing is the stock exhaust is 20 years old and still good. All stainless steel from the factory. I probably will try a straight thru muffler.
 

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Hello; watched another episode of Engine Masters. Season 7 episode 13. Exhaust cutouts. The main theme is to do tests of exhaust systems with and without a cutout. A bit different than the last episode i reviewed. has a bigger cu-in engine making big power. They run a full (3) three inch exhaust mimicking what a person might put into a car. 598 cubic inch BBC which had run 850 HP on pump gas in the past.
This test is a Header is Hooker under chassis unit with 2 inch tubes. Idea being something a person might put into a car.

First run with open headers and a 18 inch extension. yield torque 789.3 @ 4700 & HP 832.2 @6100.

Second run Three-inch exhaust system. Sonic welded turbo mufflers, H pipe and no cutouts at all. Yield is torque 721.4 @ 5300 & 788.1 @ 6100. Curves similar to run one just down lots of torque and HP.

Third run 3 inch exhaust with cutouts installed but kept capped. Yield torque 721.5 @ 5300 rpm & HP 788.7 @ 6100 rpm. Essentially the same peak power but up to about 5000 RPM lost both torque and HP. Estimate loss of 30 ft-lb of torque and maybe 20 HP. they did not say.

Next run with cutouts open. Yield torque 782.6 @ 4500 rpm & 826.5 @ 6200 rpm. Got most of both back.

Next run has the cutout further back by the muffler. Yield torque 753.4 @ 5200 & HP 813.3 @6100 RPM. Lose both significant torque and HP compared to cutout close to header. Also sounds awful according to Freiberger. You get good power back with cutout in either place compared to just muffler and closed cutout.

Guess if moderate noise is needed then run the turbo mufflers and get power back with cutouts near header. Likely straight thru mufflers will be less restrictive but louder than the turbo mufflers.

I did not find a test comparing 2 1/2 inch full exhaust to 3 inch full exhaust. .
 

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Hello; Been following this thread. I know the traditional views on exhaust but cannot say i have ever been able to test any. I have saved 84 episodes of Engine Masters however. I watched episode seven(7) of seasonfive(5). titled single vs. dual exhaust.
In the episode they run a 351 ford on a dyno. They use shorty headers. The setup is many folds.

First First they run a dual exhaust with 2 1/2 inch pipe. On the dual exhaust setup they run turbo mufflers and later a straight thru mufflers (see thru muffler.) The first run is with turbo mufflers an 2 1/2 pipes. No H nor X pipe. Run yielded torque of 405.3 @ 4100 rpm & HP 414.7 @ 6400 rpm.

Next set up is with straight thru mufflers. Same everything else. Still 2 1/2 pipes. Yielded torque of 412.8 @4200 rpm & HP of 420.5 @ 6200 rpm. Significant gain in torque between 300o to 3500 rpm. Maybe 30 ft-lb at 3000 to 3200 rpm the some lesser gain thru the rest of the rpm range. Similar for HP with maybe 25 HP gain in lower rpm range but some more all the way.

Next is a single exhaust with three (3) inch pipes. Two configurations. First has the two banks of the engine meeting at 90 degrees into the single pipe with a 3 inch turbo muffler. Yield was torque of 398. 9 @ 4000 rpm & 374.1 HP at 6300 rpm. A significant loss everywhere on the curves and the biggest loss at higher RPM's. Note - also changed the fuel mix to rich.

Next, they change the merge into a Y type. With turbo muffler yielded torque of 397.2 @ 3900 rpm & 383.5 HP @ 6200 rpm. not much difference over all but decent torque and HP gain in low RPMs to about 3800 rpm. Hardly any difference at higher rpms.

Last setup single 3 inch with Y merge and straight thru mufflers. Yield torque 422.9 @ 4000 rpm & 424.5 @ 6300 rpm. best peak overall of all setups. Thru the entire RPM curve significantly beat the 2 1/2 dual exhaust with straight thru mufflers everywhere except at high RPMs. maybe 25 ft pounds of more torque from 3000 to around 4200 rpm. Maybe 10 HP in that same range.

Again no H nor X pipe. I have watched all the 84 episodes of these dyno runs. What I glean from that is there are too many variables to make generalized statements for all engines. Change the heads or cam or headers and results might be different.
About the only thing that stands out is the straight thru muffler is a winner in this setup. Also, in a single exhaust having a Y pipe type merge works better.

I admit i was not expecting a single exhaust setup to beat any dual exhaust. Freiberger also thinks that the engine making less than 400 HP might be a factor.
Interesting. I thought that it's generally accepted that two-into-one style exhausts provide superior performance. Something about hot exhaust gases expanding into the larger volume pipe pulling a partial upstream vacuum. Motorcycle exhaust designs leverage this, unless I've been mis-informed.
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