not another headers vs. manifolds thread...

[red79]

Sorry to make yet another manifolds vs headers thread, but I have a rather specific question. I'm in the middle of a 440 dd/ street build, 30 over, zero deck, K56, perf rpm, cleaned up 902 heads with stock converter and 3.23 rear (short version: virtually identical to FLG's engine, with respect to parts and my goals).

so here's what I'm trying to decide: 1-3/4" primary headers, or clean up the pair of HP manifolds I have sitting in the shed? I've read that they flow very similarly, and it would be nice to forgo burned boots, starters, and ground scraping. so, about how much would I be leaving on the table for my highway geared dd?

[Budnicks]

The headers will out flow the HP manifolds any day, 1-3/4" headers are fine for street use or even mid range track performance.  Heddman makes a set of 1-3/4" shorty headers HED-78070 $199 at Summit Racing, that will not drag the ground & supposed to be 20-25hp over the HP manifold on a stock 68-70 440. A long tube header will be more like 25-35hp on a stock engine & more torque than the HP or Shorty header, until you get to 470+ cubes you don't need any larger than 1-7/8" tube header, then after that it depends on flow needed, rarely over 2" on any Wedge engine unless your in the 850hp+ range,& that still depends on flow.  The smaller tube will keep velocity up in the tubes & accually draw the exhaust out.   The biggest advantage the header has over the HP manifold is you don't get exhaust reversion pulses back in the exhaust ports that impedes flow, ALA performance drop compared to a header. THE HP'S ARE BETTER THAN THE SMOGGER MANIFOLDS BUT NOT BETTER! or even equal to headers.  The 62-65 Max Wedge Cast Iron Headers are the only cast manifold/header that will flow with tube headers on a B or RB Mopar wedge engine. Good luck.   Budnicks

[red79]

Thanks for the input. I looked at shorties briefly, and it seems like they wouldn't be worth it on my engine, which will be a low-revving streeter. If long tube manifolds are known to help with low-end torque, I guess I'll start hitting the header fitment in 3rd gen threads 

[oldkimmer]

........On ur build u wont see much of a difference....10 hp maybe.....and u wont have the headache...........kim............