Off the shelf cam options for marine engines
02-17-2016 | 10:29 AM
#361
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
Likes: 142
From: Elkton, MD
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.
02-17-2016 | 10:38 AM
#363
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
Likes: 142
From: Elkton, MD
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!
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!
02-17-2016 | 11:20 AM
#364
Platinum Member
Joined: Apr 2005
Posts: 2,150
Likes: 15
From: Northport N.Y.
That all deepens if you keep after it and keep tweaking it making changes in the rite spots. I added 26MPH to my boat by putting the money in the right spot. Camshaft and Heads that's it.
Last edited by 14 apache; 02-17-2016 at 11:39 AM.
02-17-2016 | 11:22 AM
#365
Gold Member
Joined: Oct 2005
Posts: 11,688
Likes: 216
From: Olmsted Falls,Ohio Marblehead,Oh
One build being mine the goal was to see props spin 5900-6000, TRS boat
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.
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.
02-17-2016 | 11:26 AM
#366
Registered
Joined: Mar 2008
Posts: 3,613
Likes: 375
From: Traverse City MI
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!
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
02-17-2016 | 11:27 AM
#367
Gold Member
Joined: Oct 2005
Posts: 11,688
Likes: 216
From: Olmsted Falls,Ohio Marblehead,Oh
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
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.
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.
02-17-2016 | 11:45 AM
#368
Registered
Joined: Jul 2007
Posts: 2,640
Likes: 14
From: MI
02-17-2016 | 11:45 AM
#369
Registered
Joined: Apr 2004
Posts: 1,268
Likes: 239
From: Michigan
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
This is kinda what I was saying at the end of post 86
02-17-2016 | 11:55 AM
#370
Registered
Joined: Mar 2008
Posts: 3,613
Likes: 375
From: Traverse City MI
I don't want to derail this thread and there's way more info about my build then what I have been able to share and what lies have been spread
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.
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.
