Header Length ???
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Header Length ???

  1. #1
    Boat 502 76Miller's Avatar
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    Default Header Length ???

    I like the look of a shorter header, but just curious on a n/a motor how short can you go before it starts robbing hp ?? Is there a sweet spot, a few inches past the collector ???

    Does this work ? Make a line at the end of your header w/ lip stick, going towards the collector.Then run the boat, and where the lip stick burns to, cut there. ????????? I have heard this works, any thoughts ??? Thanks

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    cfm
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    Quote Originally Posted by 76Miller View Post
    Does this work ? Make a line at the end of your header w/ lip stick, going towards the collector.Then run the boat, and where the lip stick burns to, cut there. ????????? I have heard this works, any thoughts ??? Thanks

    No. This myth has been proven wrong many times. Yes, I did that for years too - but not with lipstick. LOL.

    Are you asking about primary tube length and/or collector length ? Are you using mufflers ? Dry headers or water injected ?

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by cfm View Post
    No. This myth has been proven wrong many times. Yes, I did that for years too - but not with lipstick. LOL.

    Are you asking about primary tube length and/or collector length ? Are you using mufflers ? Dry headers or water injected ?
    Collector length on a set of Bassett's. No mufflers, and running dry. I have seen some cut right after the Bassett stamp, is that too short ??

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    cfm
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    Collector length can be crucial. I've seen many motors with open headers only (no mufflers/ no other exhaust tubing) pick up big power by adding 8-10" of collector on headers that had maybe an 1" or so of collector length. If you want to call an 1" or two a collector. That's all generically said of course, but don't just cut it off and leave it.

    Since dry, why don't you make the collector replaceable. That way you can test different lengths.

    On the 'marker' heat test what would happen is you'd cut the collector where it melted. Then if you re-ran the test, the marker would melt at a different spot. if you did it again, it would then melt at a different spot. You'd end up with no collector and a big loss of power. Doh ! It wasn't until doing the repeated tests that one would see the marker test actually did not end up working so well. We did this for H-Pipes and X-Pipes also. Same deal. 'marker Melt point' would keep moving. Duyam.

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    Primary tubes 28-32" depending on engine combo, rpm and tube ID.
    Collector length 12-14" depending again on combo, size and type (merge or standard)
    More info on your combo needed to make an educated (or semi-educated) guess.
    Also depends on were you want the gains. Looking for what is best from 2000rpm to 6000rpm is different than optimizing for say 5000-6500rpm.

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    Most boat headers have too large of a primary tube for the engines that they are on. Extra collector length will help that deal. You didn't say what size motor you have, RPM level, or how high strung it is. All of that makes a big difference on what is desireable. More info on your combo please. TIMINATOR
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    long collectors look like ass but make more HP. The basset twisty generally makes more power than a regular bassett.
    B1Racing.net

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    Quote Originally Posted by cs19 View Post
    long collectors look like ass but make more HP. The basset twisty generally makes more power than a regular bassett.
    I was told this and was surprised to see my non twisty header make the same power as the twisty.

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by cs19 View Post
    long collectors look like ass but make more HP. The basset twisty generally makes more power than a regular bassett.
    I was afraid that this was true !! Long collectors do look lame. I had the twisty's but had to sell cause they won't work on the new deal. Need Chevy bolt pattern for the heads I'm running this time around.

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by Warp Speed View Post
    Primary tubes 28-32" depending on engine combo, rpm and tube ID.
    Collector length 12-14" depending again on combo, size and type (merge or standard)
    More info on your combo needed to make an educated (or semi-educated) guess.
    Also depends on were you want the gains. Looking for what is best from 2000rpm to 6000rpm is different than optimizing for say 5000-6500rpm.
    Well, its going to be a 532ci. operating rpm range 3000-6500 rpm. I really don't want to loose power anywhere, but I would rather see gains on the big end if I had to make the choice.

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by TIMINATOR View Post
    Most boat headers have too large of a primary tube for the engines that they are on. Extra collector length will help that deal. You didn't say what size motor you have, RPM level, or how high strung it is. All of that makes a big difference on what is desireable. More info on your combo please. TIMINATOR
    I heard that also, the primary tubes are about a 1/4'' too big for most applications, so the collector evens it out........but looks like sh#t being so long !! My combo is a 532ci. 3000-6500rpm, single carb deal, river boat. Liked the look of a shorter header but it isn't worth loosing power, if thats the case. If it was like 5 -10 hp I wouldn't care, but you get the point.

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