460 Ford Forum banner
1 - 18 of 18 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter · #1 ·
Almost time for exhaust on my 79 f250. Approx 500 hp 460 ci 2wd. My original plan was 2.5" duals into a single muffler with a 3" exit in front of wheel on pass side but that was before I got carried away with AFR heads etc. Will this still flow enough or am I choking it to much I dont want a loud truck, any suggestions?
 

Attachments

·
Registered
Joined
·
1,587 Posts
Your going to make more than 500hp, just make it 3 inch twin into 3 inch single muffler and use the jones(same as magnaflow muffler but cheaper) 22" long muffler to keep it quiet.

Cheers, Bob
 

·
Premium Member
Joined
·
9,536 Posts
If you are getting close to 600 hp then 3" duals are needed.







Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Log In or Sign Up to View
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #4 ·
If you are getting close to 600 hp then 3" duals are needed.







Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Log In or Sign Up to View
Would 2.5" duals into a dual inlet 3" outley muffler be a reasonable compromise between flow and noise?
 

·
Premium Member
Joined
·
9,536 Posts
Would 2.5" duals into a dual inlet 3" outley muffler be a reasonable compromise between flow and noise?
A single 3" outlet is inadequate for anything more than about 460 hp. It is a simple matter of air flow.

Dual 2.5" is quieter than dual 3" of course.
Which way you go depends on expected output.

I don't have that information so I am making generalizations.





Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Log In or Sign Up to View
 

·
Registered
1990 Ford Mustang LX 351M powered!! Project Cherry Bomb!!
Joined
·
313 Posts
Moving that much air, that puppy's gotta breathe!!! An engine is an air pump.. The easier you can get airflow in and out of it the better off it'll be... Watch the Enginemasters episodes on exhaust sizing... You'll be better off with full dual 3in exhaust, and a crossover if possible..
 

·
Registered
Joined
·
1,060 Posts
You need dual 3" for sure. If you want it quiet, put the mufflers as close to the engine as possible, and double them up (four mufflers total). An H-pipe also helps mellow out the sound.
 

·
Registered
Joined
·
197 Posts
single 3" is -28% the area of dual 2.5".

I run dual 2.5-into-3 muffler and would not do it again (~425hp, heavy 4x4).

The extra flow from larger pipes is mostly beneficial at high RPM.
 

·
Registered
Joined
·
446 Posts
3" duals with a H-pipe it is, thanks everyone
One of the "Engine Masters" shows I taped did a test of mufflers of a 1000HP BBC on their dyno. They used 4" pipes and 6 different mufflers. Hooker Max Flow produced the best numbers and were one of the quieter.
It's not just the pipe size, but the mufflers will kill any flow the pipes give you.
3" pipe is a good size, but be careful of the mufflers you pick. You also want to install them right after the X pipe.
 

·
Registered
1989 F-250 HD Extra cab long bed
Joined
·
9 Posts
3" duals with a H-pipe it is, thanks everyone
Engine Masters, Season 5 Episode 7. That's where they tested mufflers with 3" single versus 2.5" dual exhaust. The engine was a 351 Windsor with AFR heads a roller cam and some other speed equipment. It was making well over 400HP throughout the test. They tested the straight through muffler versus the offset inlet/exhaust. The straight through muffler created superior power, but this depends on what you're after. One thing they did test was an "H" crossover versus the Y-type crossover. The "H" killed a LOT of power, so that's something to consider. Also, the 3" single made more power than the 2.5" dual. HOWEVER, it depends on what you're doing with the engine. You should watch the show because there's a big difference between low-end torque and top end power. In fact, they have several shows that show that just because you get more horsepower, it may be at a peak that is outside what you want. In other words, are you towing or are you going for speed.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #13 ·
Engine Masters, Season 5 Episode 7. That's where they tested mufflers with 3" single versus 2.5" dual exhaust. The engine was a 351 Windsor with AFR heads a roller cam and some other speed equipment. It was making well over 400HP throughout the test. They tested the straight through muffler versus the offset inlet/exhaust. The straight through muffler created superior power, but this depends on what you're after. One thing they did test was an "H" crossover versus the Y-type crossover. The "H" killed a LOT of power, so that's something to consider.
Sorry but do you mean an X-pipe or a Y-pipe? A Y-pipe would be single exhaust or am I missing something?
 

·
Registered
Joined
·
107 Posts
Some have done well with an H or X crossover.
OE mfr's lean towards the Y into a long resonator using the pulses for torque and power. Then, they squelch that noise into a EPA-appeasing, air rush sound while pushing 260+ Hp through a single 2.5" pipe. But hey, what do those enguneers know? 😎
 

·
Registered
1989 F-250 HD Extra cab long bed
Joined
·
9 Posts
Sorry but do you mean an X-pipe or a Y-pipe? A Y-pipe would be single exhaust or am I missing something?
Sorry. I misspoke. I mean an X-pipe. Some will use a 90degree bend (they do it on the Engine Masters program I mentioned before) and it really killed power. However, some interconnection is necessary to even the flow of the exhaust through the system. If you don't they can pulse and actually rob you of power.
 

·
Registered
Joined
·
1,060 Posts
Engine Masters, Season 5 Episode 7. That's where they tested mufflers with 3" single versus 2.5" dual exhaust. The engine was a 351 Windsor with AFR heads a roller cam and some other speed equipment. It was making well over 400HP throughout the test. They tested the straight through muffler versus the offset inlet/exhaust. The straight through muffler created superior power, but this depends on what you're after. One thing they did test was an "H" crossover versus the Y-type crossover. The "H" killed a LOT of power, so that's something to consider. Also, the 3" single made more power than the 2.5" dual. HOWEVER, it depends on what you're doing with the engine. You should watch the show because there's a big difference between low-end torque and top end power. In fact, they have several shows that show that just because you get more horsepower, it may be at a peak that is outside what you want. In other words, are you towing or are you going for speed.
You are not discussing an "H" pipe. That show had a comparison of a hard "T" into a single exhaust as compared to a smooth "Y". An H pipe connects the two sides of a dual exhaust and they stay duals all the way out. An "H" pipe has absolutely no disadvantages over an exhaust without one, unless you like the sound of separated duals better....also, the offset of the mufflers had nothing to do with hp and torque. It's the design of the silencing inside. Turbos with 3 tubes versus straight through like a magnaflow. An offset magnaflow will make the same power as a center in center out magnaflow. Just trying to stop the confusion before we get too far down the misinformation superhighway.
 

·
Registered
1989 F-250 HD Extra cab long bed
Joined
·
9 Posts
You are not discussing an "H" pipe. That show had a comparison of a hard "T" into a single exhaust as compared to a smooth "Y". An H pipe connects the two sides of a dual exhaust and they stay duals all the way out. An "H" pipe has absolutely no disadvantages over an exhaust without one, unless you like the sound of separated duals better....also, the offset of the mufflers had nothing to do with hp and torque. It's the design of the silencing inside. Turbos with 3 tubes versus straight through like a magnaflow. An offset magnaflow will make the same power as a center in center out magnaflow. Just trying to stop the confusion before we get too far down the misinformation superhighway.
You're correct about the "H" pipe, but according to the program I quoted you are incorrect about the mufflers. Their program showed that the straight through muffler on single exhaust in 3" created much more horsepower and torque throughout the range than the 2.5" dual exhaust with the turbo muffler. Throughout their test the straight through muffler created more torque and horsepower than the turbo. Engine Masters, season 5 episode 7. I don't know why they didn't test 3" dual exhaust - probably had to do with time available.
 

·
Registered
Joined
·
1,060 Posts
You're correct about the "H" pipe, but according to the program I quoted you are incorrect about the mufflers. Their program showed that the straight through muffler on single exhaust in 3" created much more horsepower and torque throughout the range than the 2.5" dual exhaust with the turbo muffler. Throughout their test the straight through muffler created more torque and horsepower than the turbo. Engine Masters, season 5 episode 7. I don't know why they didn't test 3" dual exhaust - probably had to do with time available.
Yes I know a straight through muffler will make more horsepower and torque than a turbo muffler. My statement is that the offset makes no difference whatsoever. A straight through center in center out will make the same horsepower and torque as a straight through offset in center out or offset in offset out muffler. "Straight through" doesn't have anything to do with the offset of entries and exits, it has to do with the design being one tube connecting the inlet and outlet. As in this picture. The race pro and violator are both still straight through mufflers even though they are offset in offset out. Offset means nothing when it comes to hp and torque. It's all in the internal design of the muffler, and these are all offset in offset out in this picture, but two of them are still straight through: the race pro and the violator.
Font Material property Technology Electronic device Machine
 
1 - 18 of 18 Posts
Top