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Mid length headers

983 views 15 replies 6 participants last post by  superirish 
#1 ·
So I got my mid length headers in the mail today. The primaries are actually shorter than my old bbk shorties. The collector ends at the same point as the shorties too. Is this normal? How are these better than shorties?
 
#2 ·
Accufabs? pics?
 
#5 ·
And theeenn.......>:)
 
#12 ·
There was a thread on here awhile back where a guy had a stroker small block, ran it on the engine dyno with longtubes, and then in the car with the accufab shorties, and taking into account for driveline losses he said it didn't make a drastic difference like one might expect going to shorties from longtubes.
 
#9 ·
If your existing shorties were the bottleneck to more flow through the motor, and these flow better, then they'll help at peak. What evidence do you have that the existing shorties are your bottleneck?
 
#10 ·
No evidence on a bottleneck but I understand how reading my initial post would lead to you asking that question.

I went from a very mild 302 with gt40 heads and the bbk shorties to a 363 with 11r 190's and as part of the upgrade bought the new headers. I haven't cranked the new engine yet. I chose the mid length headers b/c it was my understanding I would only be giving up 7-10 hp over long tubes and I would have more ground clearance.

I guess the appropriate question is how are the mid length headers any different than a set of shorties? The primaries are the same length as the shorties.
 
#13 ·
On the few apples to apples tests I've seen, there was never a significant difference at peak between properly sized shorties and long tubes. However, low end and mid range was significantly enhanced with properly sized long tubes. Have to be careful about generalizing though - the whole combo should be designed to work together.
 
#14 ·
I appreciate you guys chiming in and I think getting the whole combo right is the key on any engine build.

I hate to bash anyone but please keep in mind I didn't initially name the vendor nor have I contacted them about any of this but they turned my hands black when i touched them out of the box. There was mig/tig wire hanging off of the welds. I had to ream many of the bolt holes to get them to mount w/o stripping my heads. I'm just kind of frustrated with the whole deal.
 
#16 ·
I had to ream many of the bolt holes to get them to mount w/o stripping my heads. I'm just kind of frustrated with the whole deal.
I didn't have any issue with the welds on mine, but I did have to run in headers bolts a few turns, put a large screwdriver between the bolt and header and then pry toward the header tube to dimple it enough so the bolt would thread in all the way.
 
#15 ·
Yeah -- it seems to be almost impossible to find a nice quality header at almost any length. I grew weary of having to have brand new out of the box units taken to a machine shop to have the flanges milled so they'd sit flat against the head, rather than trying to "force" them into place with the bolts. A sure-fired recipe for stripped threads and constantly loosening fasteners. Not to mention cleaning up crappy welds.

Finally learned my lesson -- went with a cast stainless steel manifold on the latest motor. SO much higher quality, durable, quieter, win, win, win.
 
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