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Originally Posted by MILD THUNDER
(Post 4405123)
Imo, having a little more torque below 3500, to lose 30-40hp up top, and torque numbers from 3500 up, down as well, is that the 651 cammed combo would serve an offshore boat better. Unless of course he was pulling water skiers.
As I stated, I think the one cam was short on duration for a 540 and those heads. I would bet there was a reason, perhaps one not posted here but I'm sure we could easily find out if need be. A friend built a similar combo and RHS heads with similar lift as the custom cam but more duration and made 750. |
MT has a good point
Spending extra money for the ideal setup doesn't always equate to enough speed gain to make it worth it |
Originally Posted by MILD THUNDER
(Post 4405123)
The 325 heads and cam combo was specd by marine kinetics..
There's nothing that has been posted from th very beginning on this thread that didn't have undertones. As an outsider looking in, this was clear to me from the very first page. As a result, I'm dropping out of this thread. Good day fellas! |
Originally Posted by offshorexcursion
(Post 4405140)
MT has a good point
Spending extra money for the ideal setup doesn't always equate to enough speed gain to make it worth it |
One build being mine the goal was to see props spin 5900-6000, TRS boat
Originally Posted by Panther
(Post 4405115)
I don't know anything about these two combos other than what was posted but looking quickly at the duration numbers, it doesn't look right to me for a 540 with 325 AFR's. There's a lot of variables which I don't know anything about, other than two engines with different cam's and heads were dyno'd.
Perhaps the owner didn't want to spin the engine to 6K rpm so the duration numbers were adjusted to compensate? Was is a Bravo boat or Speedmaster? I personally would have wanted the engine to spin 6k rpm if it was a Bravo boat. With the larger heads it needed more duration to make power above 5500 which is where those 325's start to make power. I just don't know what the owners goals were with either of these builds so I can't say that either combination was right or wrong. For argument sake, what would be interesting for me to see is how the 651 did with the 325 heads and other cam did with the 290's. Or how either engine would do with similar duration numbers with everything else being similar. |
Originally Posted by Panther
(Post 4405143)
I had a hunch this would come next when it was posted.
There's nothing that has been posted from th very beginning on this thread that didn't have undertones. As an outsider looking in, this was clear to me from the very first page. As a result, I'm dropping out of this thread. Good day fellas! Bob supporters have constantly attempted to derail it from the first few posts Give Haxby some respect like you used to Just because he does not partner with Bob does not make his knowledge shared less vaulable |
Ask me any reason or question I have no issue posting any info, my goal was 700hp at 6000 to spin my 25 mirage plus props to 6000 as with old engines were 600 hp spun those same props to 5500 all day. The thought was spin drives faster, less load woukd help TRS live... That was main reason shooting for 6000, now they will with a 23p prop but the design was to keep the 25's my cruise already sucks with 23's it's even worse. Boat went .2 mph less with the 23's but they went 6000
Originally Posted by Panther
(Post 4405137)
The 290 heads are the reason it made more torque. The duration carried it up top. With more duration, the 325 would make more power up top and more torque from 4000 rpm upward IMHO.
As I stated, I think the one cam was short on duration for a 540 and those heads. I would bet there was a reason, perhaps one not posted here but I'm sure we could easily find out if need be. A friend built a similar combo and RHS heads with similar lift as the custom cam but more duration and made 750. |
Originally Posted by offshorexcursion
(Post 4405140)
MT has a good point
Spending extra money for the ideal setup doesn't always equate to enough speed gain to make it worth it |
The peak velocity the exhaust port sees is at low lift. With the exhaust blowing down and loosing velocity lift IMO is no where near as important as duration. (From Post #355)
This is kinda what I was saying at the end of post 86 |
Originally Posted by JRider
(Post 4405177)
Do you wish you would have kept your blower motors?
Anyones welcome to call me anytime 231-534-5060 and maybe once everyone gets along I can openly share my story without drama so everyone can learn, no matter if they agree or not. |
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