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1 Attachment(s)
Originally Posted by getrdunn
(Post 4658426)
Thats understandable if you made no other changes like jetting, timing, etc. I don't wanna hijack this thread but just found this to be an article worth posting after I had a couple close calls after monitoring EGT's on a 420 mb supercharged BBC engine while not having AFR at the time. Spark Plugs and EGT's were telling two different things. Attachment 576070 |
Gpm, what were the cam specs between the two? Curious if the reduced egts were from exhaust duration, or overlap, or exhaust timing events .
good topic |
Originally Posted by endeavour32
(Post 4658440)
Hijack all you like
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I've lost track of how many cams I tried in my motor, 10 or 12, all solid rollers, 112 or 114 ls, either in my boat on the dyno or both. Not a lot compared to an engine builder. All were custom grinds from Crane, Comp, or Bullet. I tried between 4 and 14 degree difference between intake and exhaust. Ranging from 266 to 276 intake, 270 to 286 on the exhaust.
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Originally Posted by GPM
(Post 4658480)
I've lost track of how many cams I tried in my motor, 10 or 12, all solid rollers, 112 or 114 ls, either in my boat on the dyno or both. Not a lot compared to an engine builder. All were custom grinds from Crane, Comp, or Bullet. I tried between 4 and 14 degree difference between intake and exhaust. Ranging from 266 to 276 intake, 270 to 286 on the exhaust.
What CI? Just curious. I think that's awesome your a kind of guy who ongoing looks for more power or what works best with your particular build. |
598
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Originally Posted by GPM
(Post 4658480)
I've lost track of how many cams I tried in my motor, 10 or 12, all solid rollers, 112 or 114 ls, either in my boat on the dyno or both. Not a lot compared to an engine builder. All were custom grinds from Crane, Comp, or Bullet. I tried between 4 and 14 degree difference between intake and exhaust. Ranging from 266 to 276 intake, 270 to 286 on the exhaust.
Mine isn`t optimal, i`d like to know if changing is worth it. |
For my 598, M5 Procharged, CNC BB2xtra or CNC Big Duke head, the 112 lsa and 8 to10 degree split worked the best. The 4 degree split limited the rpm and ran higher egt's, the 10 degree split just kept going. I didn't notice much difference with the 14 degree split from the 10. The 276/284 @ .050 with BB2xtra ran the same RPM range as the 272/280 @ .050 Big Duke. The good ports on the Xtra's at .700 were 404 intake and 315 exhaust, Big Dukes were 453 and 333. Bullet and Comp seemed to like the 10 degree split with the blower. The last cam I ran was the 268/278 @.050 .758 lift. it idled nice and seemed to do alright on top end. My combo was different than yours, it's hard to say what will be best for you. I was experimenting for my own knowledge.
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One thing for sure is you get "faster" at changing the cams whether it be in or out of the boat. I swapped out more in my second boat 24' challenger than any. Being close from the start if I saw 1 mph faster with 3 plus swaps I was l lucky. Young and ambitious and then I discovered reversion.... :daz: if I could make a good living trying different cams in various builds I have to admit I probably would. Long as no one was chattering in my ear all day and didn't have to deal with customer service. :bong: |
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