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Exhaust Manifolds and are you Pleased

FitzyB5 said:
https://www.hemmings.com/magazine/mus/2017/07/How-Hot-The-Hemi-/3750986.html
This is the 426 Hemi I purchased from Don at RAD machine and transplanted in my 67 Coronet RT tribute convertible. You can see dyno results with factory headers vs racing headers. Not a huge difference.
Click to expand...
Yup, but those are some of the better factory manifolds ever installed.You’ll always get a more “tinny” sound from headers. Lose heat faster when shutdown, and then difference in tubing dia. makes a difference on the street also.
 
I'll stand by my statement of headers help
more at above 3500rpm.
Check this out on Dyno tests.
Granted if you go by sound while driving, it
sounds faster
 
If power is your main concern, go with the headers. If originality is your goal, use the stock manifolds. I'm building a Max Wedge replica, with a stroker in place of the 426. I have been beaten down by my engine builder, for using the original style exhaust manifolds, as I'll be loosing all those available ponies, and burning the paint off my valve covers too. I plan on driving the car when & where I want, and tracking the car also. I don't really care if I ever win any races, So the maximum power is not my goal. Bottom line is I want the Classic, Original Look that made those first S/S cars a part of history...
 
I like my manifolds on my stock build, the Charger in my avatar. Can still have a conversation in the car. Installed them w all new hardware. My other car will get headers. That one will go to the track.
 
There was a thread on moparts recently....... 500”, 6bbl, TF240 heads, hyd roller cam........ headers and hp manifolds...... on the dyno.

Headers......90hp better than manifolds.

How much you can gain or lose is totally dependent on the combination......but on any decent 500” type build, don’t kid yourself into thinking you’re only leaving 10-20hp on the table.
It’s def going to be well over that.
 
I see the difference on the Hemi dyno test @ 3000 RPM was only 7 horsepower (272.1 vs 279.1).
 
oldbee said:
Either way IMHO, if HP manifolds; don’t go crazy on the camshaft. Read the arengineering.com tech pages. Very interesting.
Click to expand...


Talked about Keeping Duration under 245 degrees @ .050" Lift




Anyways I am running the factory HP manifolds on my little factory 383 / 432 Stroker

E Street 75cc heads - 10.5-1 Compression
Comp Cams XE275 HL

Factory 727 Trans rebuilt - Turbo Action Valve Body - 3:91 Sure Grip

I can roast the tires off idle @ 700 Rpms from Green Bay to Chicago

Car has plenty of Torque

 
Doesn't mention if they re-tuned and tweaked the carters in the hemi link, you'd hope so but who knows...sometimes in the magazine dyno runs they just swap stuff and run it to see the gain vs. the previous configuration. All I can say is for 50+ years headers have been the go-to mod, for a reason..they work. Manifolds work great, especially on a torquey big-block. Headers will just work better.
 
Depends on the build, purpose, etc.
All my engines are mild performance builds so I stayed with factory exhaust manifolds, and I'm content.
 
TTI’s here. Ceramic coated. Less weight and cooler underhood temperatures. No leaks.
 
Johnpat said:
I'll stand by my statement of headers help
more at above 3500rpm.
Check this out on Dyno tests.
Granted if you go by sound while driving, it
sounds faster
Click to expand...
You are partially correct because it is combination dependent. If that is the rpm you seen pick up big, then I would point to the cam being large and the combo needing headers.
 
Read this:

http://www.moparts.org/Tech/Archive/bb/550hp.html

FlagCraig said:
Who has put their original exhaust manifolds (instead of headers) back on after a complete engine rebuild and are you happy?

Reason I'm asking is we are at the final stages of my stroker (505) rebuild and the original exhaust manifolds we took off look fantastic. I'm just questioning the investment of headers when it's never going to see the track. Will any loss of HP (20-40?) without headers be that noticeable when street driven.

Also we are using the original 915 heads that have been machined and ported. Thx.
View attachment 676614
Click to expand...
 
IMO, the bottom line is this.....
Unless you’re copying a complete known combination, where someone has already done the A/B test of headers vs manifolds....... the only way you’ll know how much power you’re leaving on the table with you’re new combo....... is to test it.
 
What cam is in your stroker? If you didn't go nuts on duration, you may still have a fun big block with stump pulling power. And that is a fun street car.
 
When we rebuilt the 340 on the Challenger 3 years ago it was stroked to 416. We went with the original exhaust manifolds. That whole car was a rotisserie restoration. And my goal was to try and keep it as original as possible except inside the guts of the original motor. When I push the pedal on that car it sometimes scares me it is so quick. I do like the original look. Maybe I'm answering my own question. It can always be changed out if needed.
 
FlagCraig said:
When we rebuilt the 340 on the Challenger 3 years ago it was stroked to 416. We went with the original exhaust manifolds. That whole car was a rotisserie restoration. And my goal was to try and keep it as original as possible except inside the guts of the original motor. When I push the pedal on that car it sometimes scares me it is so quick. I do like the original look. Maybe I'm answering my own question. It can always be changed out if needed.
Click to expand...
 
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