V6-specific exhaust theory.

wicked93gs

10 Year Member
Sep 30, 2006
651
31
38
Nashville TN
So I wanted to start a topic to discuss designing an custom exhaust system. I have a 3.7L in a 1966 Mustang. I just got done building a set of equal-length long tube headers for it....but wanted to start thinking about the rest of the exhaust system. From what I have read since v6s are inherently balanced(unlike v8s) they gain no actual performance benefit from a H-pipe or X-pipe(though it does alter sound). Presumably it is actually better to run true duals on a v6...with a separate system for each bank of cylinders since it avoids the turbulence of a crossover pipe of whatever type. I was wondering if anyone had more insight on this idea. It would certainly be simpler to have true duals(and slightly lighter). My goal here is to build a system that squeezes every last HP out of the exaust...the plan is true duals into a glasspack on either side with a resonator after each pack to hopefully tune out some of the resulting drone. The headers themselves are 35" primaries of 1 5/8" diameter reduced down to 2" at the merge collector before returning to 2.25" after the trumpet portion of the collector, and 2.25" piping all the way back.
 
  • Sponsors(?)


David Young

Active Member
Sep 16, 2012
135
12
38
66
Clinton, Tennessee
I have more power running my Magnaflow Street series (mid range on sound) than I do running my Magnaflow Competitions. The competitions are straight pipe and very loud. The 3.7 likes some backpressure . You talking about running the exhaust without a x or h mid pipe? If so, I'm old and remember knowing a few people did that in the late 1960's. As a teenager (I was 16 years old in 1969 :() I thought they sounded like pure crap. These were v8 cars of the 60's so maybe the 3.7 might sound ok but I don't know of anyone who has done this. Maybe, check youtube for video's.
 

wicked93gs

10 Year Member
Sep 30, 2006
651
31
38
Nashville TN
I have more power running my Magnaflow Street series (mid range on sound) than I do running my Magnaflow Competitions. The competitions are straight pipe and very loud. The 3.7 likes some backpressure . You talking about running the exhaust without a x or h mid pipe? If so, I'm old and remember knowing a few people did that in the late 1960's. As a teenager (I was 16 years old in 1969 :() I thought they sounded like pure crap. These were v8 cars of the 60's so maybe the 3.7 might sound ok but I don't know of anyone who has done this. Maybe, check youtube for video's.
V8s are completely different...they need the crossover pipe because of the out-of-balance cylinder(unless you make crazy headers like the GT40 where the out of balance tube crosses over to the opposing header collector)


For reference: The exhaust system from a Ginetta G50(which also uses a Ford 3.7L making 315-355HP depending on trim)

screen-shot-2016-09-13-at-10-39-20-pm-png.png



And a sound clip from said G50:

View: https://youtu.be/9IaZW8TbOpg


As you can see...no crossover pipe(and I personally like the sound, though sound is very much subjective).

Also interesting to note on this exhaust system is that after the merge collector necks down it doesn't flare back out again like most...it looks like it necks down to 2.25" and stays there the entire time(probably to maintain velocity). I do wonder why the cats are so far downstream though...obviously catalyst light-off time isn't of any concern to them...I am wondering if there is an advantage to placing them that far away from the collector or if its just where they had roon on the chassis
 
Last edited: