Horsepower TV cam
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From: Los Angeles
Horsepower TV cam I was watching a rerun of Horsepower TV today. They were building a stroker. The interesting thing is that they had a cam ground changing the firing order of the #4 and #7 cylinder. This change yielded a gain of 30hp (engine dyno). I was suppose to increase air flow.
Originally Posted by Asmodeus
well, I highly doubt the only thing they changed on the cam was the firing order. most gains were likely made elsewhere.
Well you probably didn't watch the show then. I watched it this morning and it was a staright up test on their new engine dyno and all that was changed was the cam. It was on a SBC. What incentive would they have to make up the numbers. I don't even think they mentioned a cam maker's name.
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Verdad Gallardo They didn't say it was or wasn't, but the point of the test was to confirm or deny whether changing the firing order had an effect on horsepower. Their contention was it allowed a better mix of fuel and air. I couldn't give 2 squats about it one way or the other, but what would they be proving or disproving if they changed other parameters on the cam. The firing order effect would not be measurable. If you saying they snuck in a completely different cam profile to prove something they have no benefit in proving, then by all means "Conspiracy Theory" away!!
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Joined: Apr 2006
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From: Naperville, IL
well, who knows if they had the same profile ground or not, or if it was even available.. I'm not saying it was a conspiracy like "WMD" style conspiracy or "yellowcake uranium" conspiracy.. they had a show to do, a time to do it in, and MAY have left out a detail or 2 getting as close as they could to the original lobe specs. 30 whp the norm for changing the firing order on an old SBC? and this is just now being reported on/common knowledge? sorry if I am a bit skeptical.
I'm just messin' with ya on the Conspiracy stuff. No, it's not just being reported. They actually stated on the show, the idea has been around a while and I guess people were changing the firing order by other methods. Apparently the cam method is fairly new and they thought it would be a fairly easy test to do on their new dyno. The segment really wasn't even about the cam, it was about showcasing their new engine dyno room they had put in the shop and showing how having an engine dyno on premises will allow them to measure changes like this very quickly and easily without going to another shop. I think they were as surprised as anyone at the results.
Bryan
Bryan
and no, I did not see this episode. 
The SBC 4/7 swap has been around decades. The off-the-shelf selection is extremely limited, available in only large solid roller grinds, and thus isn't very popular. Besides, real world testing (not HPTV 
) has shown gains on only fairly stout SBCs. Your common mild 350 will not yield any additional power. And the LS1 has more than just a 4/7 firing order swap...
) has shown gains on only fairly stout SBCs. Your common mild 350 will not yield any additional power. And the LS1 has more than just a 4/7 firing order swap... 
i think the theory behind the 4/7 swap is to change when the air pulses in the intake occur to get better air movement through the intake manifold. it is something that they tried in Nascar many years ago and got outlawed.
Launching!
Joined: May 2005
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i had the 4 &7 swap on my last 555 shafiroff motor, and everyone i know running in the 565"+ range has a 4/7 swap. funny thing, it's a pretty common mistake to make (just once) but it would run 10.80's with the 4/7 swap cam and standard firing order, when the firing order issues was corrected it went 9.50's :lol
Uhhh...these Are Still Available In The Compcams Catalog Since Like Jesus Was Around...look For 4/7 Cams In The Online Catalog Under Chevy...and Stop Watching Tv! Your Gonna End Up With A Bunch Of Edelbrock Everything, Msd Everything, And Flowmaster Jizzunk! Do Some Research...don't Buy Just Because It Was On Monster Block Tv Specials...
Uhhh...these Are Still Available In The Compcams Catalog Since Like Jesus Was Around...look For 4/7 Cams In The Online Catalog Under Chevy...and Stop Watching Tv! Your Gonna End Up With A Bunch Of Edelbrock Everything, Msd Everything, And Flowmaster Jizzunk! Do Some Research...don't Buy Just Because It Was On Monster Block Tv Specials...
