Headers vs Hi-op manifolds

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1970Duster

1970Duster

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So for my 400 HP 340 which would be better Doug's headers or 340 hi-op manifolds? Would I lose a lot if I went with the manifolds and has anybody had their manifolds coated like the headers come? Also am I going to have problems with either inconjunction with my eddy head? Thanks in advance (if you wanna see the specs to my 340 build it's http://www.forabodiesonly.com/mopar/showthread.php?t=153956
 
Screw the manifolds!

(Why is this allways asked?)
 
I lost 1.4 seconds and 13 miles per hour in the 1/4 after switching from SuperComp headers and 3" exhaust to 340 manifolds and a 2.5" TTI system.

(and other minor changes)

My results, I'm sure, are not typical and your losses will really depend on your build and where you are making your power.
 
Because of their design of individual pipes for each port, headers will always make more HP than most manifolds.
 
You are going to lose HP with manifolds , what HP you making ? Or did you not dyno it after the build ? My guess was 450+hp . My build with less cam and ported j heads makes 412 hp , guessing yours will make more .
Manifolds are fine for stock builds .
 
I'd guess the difference would be in the 12-15hp range at peaks between the Dougs and the 68-70 340 manifolds.
 
So not really worth it to use the 340 manifolds.
 
1970Duster said:
So not really worth it to use the 340 manifolds.
Click to expand...


That depends on what one a person wants. On a mid/mild build where you are only turning 5,500 rpm the manifolds won't hurt "as" much. You also won't have to deal with header issues (although I have never really had a problem with headers).

On something like my build, high RPM (8,000), high compression, going to manifolds will kick your ***.
 
Hyd or solid roller?

If the heads and cam don't give up, it will spin 6500-6800 EASY!
 
Locomotion said:
This is an article on a 300hp engine. Headers would help even more in the 400+ range.
Mine puts out well over 400 and I am very happy with the results from TTI 1 5/8"-1 3/4" step headers as are several other Stock-classed cars.

http://www.moparmusclemagazine.com/...pp_0307_mopar_crate_engine_exhaust/index.html
Click to expand...

going by that test my hedman tight tubes do well , considering they drop in don't hit bottom , and because of design should last , hp off by avg 5 torque off by avg of 6 at peak , better numbers at higher revs . not bad

155_0307_exh_dyno_z.jpg
 
My 340 Duster has the HP manifolds on Edelbrock Performer rpm heads...be careful!! My driver-side manifold cracked at the rear as it was pressing on the head. I had to grind some of the head to get the clearance needed.... Anyone have an extra left side manifold?
 
Ehbody said:
My 340 Duster has the HP manifolds on Edelbrock Performer rpm heads...be careful!! My driver-side manifold cracked at the rear as it was pressing on the head. I had to grind some of the head to get the clearance needed.... Anyone have an extra left side manifold?
Click to expand...

WOW!!! I will definitely check that out when I bolt my manifolds up to fire my motor up the first time (break in on the dyno, im not messing up my headers).
 
jerry6 said:
going by that test my hedman tight tubes do well , considering they drop in don't hit bottom , and because of design should last , hp off by avg 5 torque off by avg of 6 at peak , better numbers at higher revs . not bad

155_0307_exh_dyno_z.jpg
Click to expand...
With these figures when they ran the headman, TTI,Hookers on what engine did they run these on to get these figures.
 
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