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Posted

I am trying to determine primary tube diameter needed for my AI car ('89 Mustang). My weight (2825) puts me at 295RWHP and 310 RWTQ. I'm currently running a stock bottom end 302, but will most likely go with a stroker (331) for the 2008 season.

 

I have the possibility of picking up some used 1 3/4" primary BBK longtubes with H-pipe for approx $300 but am worried that it will hurt more than help on the current 302 and possibly be even too big for the 331 considering the power numbers I need to turn.

 

I am currently running JBA 1 5/8" storties, for whatever that is worth in the discussion.

 

Should I hold out for a set of 1 5/8" primary longtubes, or will the 1 3/4" not hurt too bad. Exhaust sizing is outside my comfort zone.

Posted

I don't know jack about Mustang headers, possible power increases, etc... but I can tell you that on our 4th gen Camaro long tube headers became the lowest point on the car and prevented lowering the car further. We're probably going to switch to shorties at some point (when we run out of other projects).

 

Jason

Posted

Stay with the 1 5/8th for your set-up. The large headers would be great for a lot more cubes/big heads or super charged/turbo. The 1 5/8th long tubes will give you 10 more HP (5.0L Ford Dyno Tests) over the shortys, that's your question, is it worth it? You will also need O2 sensor extensions (if EFI) and change your mid-pipes, which you will have short H w/the deal, X pipe would be worth 3 HP more tho. SBF love smaller tubes!

Pass on the 1 3/4 and wait for the 1 5/8th long tubes w/X pipe, my 2 cents.

Posted

Although new to the NASA scene, I have a lot of experience with 302's , Boss 302's , 351 Clev , and the Big Chev.. You need to be passing a lot of air in a 302 to need 13/4 header. Stay away from the shorty's , there is no tuning ability in this type of header . The muffler is another place to be of concern . Get a good muffler that is free flowing. In that power range I would run the 15/8 , full length header with 21/2" muff.

  • 3 weeks later...
Posted

I ended up with BBK 1 5/8" LT's with a BBK X-pipe. I'm having to heavily modify the X-pipe to fit my motor setback and Griggs T/A. But hey, if it is supposed to fit the first time, it's not a race car...

 

Thanks for the suggestions guys...

Posted

The BBK setup is a good choice. Other than that, I would have suggested some mid-length headers for that setup. If you can, cut the collector off and weld/adapt the pipes direct to the headers which makes it more free flowing, and use 3 inch tubes. You wont have to change it after that.

Posted

Andy,

The only problem with welding the X-pipe directly to the headers is I cannot remove the transmission without jacking up the motor to remove the headers... big PITA.

 

I am however, cutting the ball/socket joints off the X-pipe to muffler connections so I will be able to drop everything after the headers as a single unit.

 

I'm having to use these Dr. Gas frame clearance tubes to clear the Griggs T/A mount. I should have it fabbed and in the car tomorrow. I will post some "installed" pictures then.

 

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Posted

I understand, what we did to avoid the PITA of that, is after the pipes come down under the body, just use slip pipe with circle clamps, so you can still separate it for repairs...., the slip pipe does not close up as much as a collector does, more flowing....

 

look forward to seeing the pics....

andy

Posted

Engine size makes a ton a of difference as well. With your current combination, you may need a better flowing header (long tube). With the stroker motor, you won't need the long tubes. They are harder to work around, cost more, and have more clearance problems. I've got a set of jet coated Hooker super comps that look great, but the car sits too low for them. They cost a ton of money and now I don't need them.

Posted

I finally got everything welded up and in the car. X-pipe is 10 inches further forward than the stock BBK unit, the Dr. Gas frame clearance tubes gave me an additional 1/2" clearance, so now the exhaust is 3" off the ground instead of 2.5".

 

I still have the T/A mount tabs that I need to buzz off the side of the subframe rails, but otherwise, the underside looks a whole bunch better.

 

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