Header selection help

[marshall_mosty]

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.

[AI#97]

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.

buy em the 331 will thank you later!

[j3ffbrooks]

Marshall,

When I had the 331 in my car I had to choke down the motor to make the numbers. I was using stock 302 headers to make 322/330. Long tubes might even out the numbers but will also alter the hp/trq curves.

My suggestion is to build the motor and dyno with shorties and a restrictor plate. Then go from there.





.

[macstang]

fwiw

My old combo. tired 302, GT40P heads, TFS stg 1 cam, cobra intake, 70tb, 73 c&l, BBK long tubes, H pipe, full exhaust.

285/314

Current combo, fresh 347, TFS TW heads, 24 lb injectors, all the rest same as above.

326/376

In my opinion, 1 3/4 will hurt your lower end, even with a 331.

My torque curve has over 300 from 2600 rpm, the HP runs out because of intake size, and cam. I changed the intake, but havent dynoed.

BBK long tubes sell on Ebay fairly often from 200-250.

Bull got a pair for 175.

Hope this helps, happy election day.

[macstang]

BTW, i do have a windows dyno program that turns out pretty accurate on the motors I have built. you can change exhust size and many other parameters. I can shoot it to ya, or perhaps I can post it somewhere for all to d/l.

[jeffburch]

Hope this helps, happy election day.

OMG, in my biz, this is the worst day of my life.
I hate election day.

thanks tho, back at ya.
jb

[RichardP]

I don't believe your combination warrants the hastle of long tubes. At your weight you can easily make your numbers with shorties, especially in a 331.

Richard P.

[marshall_mosty]

I don't believe your combination warrants the hastle of long tubes. At your weight you can easily make your numbers with shorties, especially in a 331.

Richard P.

Richard,
I really only considered long tubes because I destroyed my 9 yr old H-pipe during Sunday qual. I did a "high center slide" across the curbing in T1A (right side before the carousel). That flattened the bottom side of the tubes while shoving it up into the T/A mount. I went down to about 1" tall in the "crush zone".

Also, I'd like to maxize some of the 4th order pulse wave in the header primary tubing to get as much scavenging as I can.

So my dilemma was, $229 for a new bLiNg X-pipe or shell out a little more cash and get LT's and a X-pipe for that combo. I can easily sell the shorties for decent money to defray the cost of the LT's. Since I'm trying to maximize "area under the curve", the LT's should help.

My "evil" side got a hold of the credit card yesterday and did some damage. I have a set of BBK Long Tube 1 5/8" headers coming with a matching X-pipe. That "gear" should be on my doorstep on Thursday so I can slam it in the car on Friday and Saturday night.

"If" I can work everything out... I "may" also have a custom cam in the car for next season. :twisted: That possibly will have to wait for 2008, but I have to see where the accounts are sitting after X-mas!

I'm looking for a 317RWTQ tabletop up to about 5K... hopefully.

[AI#97]

I don't believe your combination warrants the hastle of long tubes. At your weight you can easily make your numbers with shorties, especially in a 331.

Richard P.

Richard,
I really only considered long tubes because I destroyed my 9 yr old H-pipe during Sunday qual. I did a "high center slide" across the curbing in T1A (right side before the carousel). That flattened the bottom side of the tubes while shoving it up into the T/A mount. I went down to about 1" tall in the "crush zone".

Also, I'd like to maxize some of the 4th order pulse wave in the header primary tubing to get as much scavenging as I can.

So my dilemma was, $229 for a new bLiNg X-pipe or shell out a little more cash and get LT's and a X-pipe for that combo. I can easily sell the shorties for decent money to defray the cost of the LT's. Since I'm trying to maximize "area under the curve", the LT's should help.

My "evil" side got a hold of the credit card yesterday and did some damage. I have a set of BBK Long Tube 1 5/8" headers coming with a matching X-pipe. That "gear" should be on my doorstep on Thursday so I can slam it in the car on Friday and Saturday night.

"If" I can work everything out... I "may" also have a custom cam in the car for next season. :twisted: That possibly will have to wait for 2008, but I have to see where the accounts are sitting after X-mas!

I'm looking for a 317RWTQ tabletop up to about 5K... hopefully.

and the combination for that is to build 360 rwtq and choke it down either with the tune and timing/fuel, or the intake. The issue with choking is that after 4800 or 5200, the power falls on it's face. We compared JG's dyno to mine a few months back and while he had flatter torque down low, I made considerably more power up top all the way to 6500.

I guess I have just found a great combo for what we are doing with these motors. Hence, why I plan to change nothing and drop the extra 120 lbs out of the car I have been carrying around with me... The roof comes off in a few weeks and there is another 20-30 lbs of steel coming out in the trunk....then maybe 30 lbs off the driver! You skinny guys have it easy!!! :wink:

[j3ffbrooks]

My "evil" side got a hold of the credit card yesterday and did some damage. I have a set of BBK Long Tube 1 5/8" headers coming with a matching X-pipe. That "gear" should be on my doorstep on Thursday so I can slam it in the car on Friday and Saturday night.

Well good luck "slamming" that in. I think Richard described it best as a "hastle".