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Discussion Starter #1
Don't show more of a HP gain,considering how restrictive looking the factory log manifolds are. I mean they look like something from the 50's!!! For instance,and I know this is apples to oranges,a test on a new 1971 340 Dodge Demon,rated at a real 275 HP,picked up a half second in ET,and gained 4 MPH in the 1/4 mile with a cheap set of street headers,through the stock mufflers,no other changes. These cars came with good flowing cast iron exhaust manifolds. Opened up the Demon ran 13.6s at 104 MPH vs.14.4 at 98.6 with stock manifolds. Not bad for an $ 80.00 mod! You would just think that the Bullitt would pick up more than 3-5 HP with a shorty header,considering the shape of the stockers.

<font size=-1>[ This Message was edited by: Mus408 on 2002-01-14 19:55 ]</font>
 

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I think the cats are where the restriction is. I just put on JBA cat4wards and picked up minimal gain. I'm putting on a MAC Prochamber Wednesday and will run it again without cats and just the stock mufflers.

I'll let you know.

Headers and 80mm MAF = $1200! = 4 rwhp gain!

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Wade Koch
3.73s
Steeda Tri-Ax
Pro-M 80mm MAF
JBA Cat4ward Chrome Headers
MAC Prochamber


<font size=-1>[ This Message was edited by: h1resq on 2002-01-14 23:27 ]</font>
 

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Mus408,

Roushraven got really good gains from adding LT's and an off road H-pipe on his car. I think his gains were in the neighborhood of 20+ rwhp and 20+ rwtq. The article about his car is in MM&FF. The nice thing is that the gains were really solid over the entire rpm range.

Eric

I'll have to arrange a dyno after mine go on to see if I get similar gains.
 

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I was going to put headers on when I put the Vortec on and was told by Johnson Motorsports that they did not get much of a horsepower increase, they said just put a offroad X-pipe and take the cats off.(Interestingly it will still pass emisions because the elec. smog pump is still on).
 

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How can Johnson Motorsports say it won't give you any gain?

Roushraven got 20+ rwhp and 20+ rwtq on a naturally aspirated Bullitt.

I understand if they said it is not worth the money for the gain. I have heard this from people if they have someone do the install and pay $700 for installation + $700-$900 for parts. I will be doing the install myself so I'm only shelling out $900 and I feel 20 rwhp and 20 rwtq across most of the rpm range is worth it. Plus it will help youi even more when you free up the intake side of things.

Eric
 

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Thanks Eric. And by the way Brad1790 also got the same gains when he added long tube headers to his car and there is a significant number of GT owners on the Corral who also post similar gains.
 

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Discussion Starter #7
Do you think the 1 1/2 dia.headers would work better for torque. I assume the LTs out now are all 1 5/8 dia. I believe reading from a header builder,that for 300-325 HP, 1 1/2 would work best. I used 1 5/8 tubes on my 302s. It just that Paul,of PHP, remarked that the LTs would hurt the low end torque...2000-3000 RPM.
 

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Isn't the idea behind headers that they improve scavenging through resonant tuning? To use an engineering analogy, if the Q (selectivity) of the system is high then the bandwidth is narrow (only effective in a relatively narrow RPM range) and when you are outside of that frequency(RPM) range your performance can actually be decreased. Maybe this is what Paul from PHP was referring to....the effectiveness (or lack thereof) of the "tuning" throughout the rpm range?

Mark
 

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Damn i hope i get more than 4rwhp from my headers. I don't know which ones i want yet long tubes or shorty??? Can any of u guys help me i need some ground clearance cuz i drive my car to school and there are some big ass speedbumps iam going to do a whole exhaust bassani catted x pipe and catback but what headers??

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Wes, tru blu #2968, 13.94...stock
4.10's,mac cold air kit,steeda t/a,
steeda pullies, pro 5.0

<font size=-1>[ This Message was edited by: 1248bullitt on 2002-01-17 17:50 ]</font>
 

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The Feb. issue of MM&FF has a really good story on the headers for you. Kook's custom headers in N.Y. answers some good questions , as well as educates, on scavenging and pipe requirements, etc. for different applications. Hope this helps a bit.
 

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Discussion Starter #11
Yes that was a good article on header design. Main thing to remember for STREET USE,is don't go to big on the tube diameter. There are street headers and race headers. For street use I look for gains in the 2000-3500 RPM range.Thats where you drive it most of the time.
 

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Here's a look at the power curve.
Stock with headers and off road h-pipe

Sock with headers/h-pipe/pulleys
 

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Roushraven,

It looks like the first dyno graph shows actual HP not SAE corrected. IS the SAE corrected?

Just want to know so I know if I'm comparing apples to apples when I look at the original and the runs on the second graph,after the upgrades, which say they are SAE corrected.

Eric
 

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All are SAE
 
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