how much Horsepower?
06-01-2003, 03:17 PM
#41
Interesting thread
Caveman,
Here's something that I think you'll find interesting for comparison.
I have a 32' Active Thunder with Bravo One XR drives on Stellings extension boxes. I'm running a pair of naturally aspirated 540's with a cam very close to what you are using now. My engine, cam, and head combination is all most identical to the "T" as Mikehtmsr24.
My hydraulic roller cam specs are 236*/244* @.050" on 114* lobes,
9.6 comp ratio,
Dart Pro-1 310cc heads fully ported to about 120cc,
Dart single plane intake manifold, Holley HP-950cfm carb using #78 jets on all four corners
4.50" pistons
4.25" stroke
6.385" rods
Stellings full length tubular headers
32* avdance
Engines dyno'd made 651hp @5000rpm and 682hp @5500rpm
The boat weighs about 8000lbs dry and runs about 87.5mph GPS with a full tank of fuel (30" Bravo One lab finished props). By the way, my hull has a pretty good HOOK in it that I need to have removed and I am still playing with props.
I prefer the low maintenace of the hydrualic roller cams vs a solid/mechical roller or flat tappet cam. This purely my preference for the reasons I like. If you want as low of a maintenance engine as you can possibly make it then the hydraulic roller cam/lifters are the way to go. Just don't go past the 5800rpm limit.
Your heads are fine but, as Bobby Daniels has mentioned, they are not up to the full port work that Mikehtmsr24 and I have had done to our aluminum heads plus we are running a little more comp ratio than you.
Here's an experience a friend of mine (Doug AKA "Pure Adreniline") went through about a year ago. He has a 35' Cigarette with a pair of 540's with new World Products 308cc cast iron heads with bowl port work done by "JimV", has the exact same cam as you are running, 9.0 comp ratio, 850cfm Holley carbs, dual plane intake manifolds and his dyno'd out at 595hp @5200rpm.
In his quest for more power, the following year he pulled one of the engines and put it on the same dyno, installed a larger cam(240*/250* at 50 lift) and the engine did NOT like it at all!---At least that is what the dyno numbers were telling him. I think Doug told me that it didn't even make the power the previous cam he had in it even by advancing/retarding the cam and I think they even tried a Dart single plane intake with it as well. Whatever the reason was, the cam change wasn't worth the switch, so they re-installed the cam he previously had in it.
Maybe Doug will see this post and chime in here.
Also, I suspect the magazine did NOT have anywhere NEAR a full tank of fuel in that boat when it was tested for the article!
Here's something that I think you'll find interesting for comparison.
I have a 32' Active Thunder with Bravo One XR drives on Stellings extension boxes. I'm running a pair of naturally aspirated 540's with a cam very close to what you are using now. My engine, cam, and head combination is all most identical to the "T" as Mikehtmsr24.
My hydraulic roller cam specs are 236*/244* @.050" on 114* lobes,
9.6 comp ratio,
Dart Pro-1 310cc heads fully ported to about 120cc,
Dart single plane intake manifold, Holley HP-950cfm carb using #78 jets on all four corners
4.50" pistons
4.25" stroke
6.385" rods
Stellings full length tubular headers
32* avdance
Engines dyno'd made 651hp @5000rpm and 682hp @5500rpm
The boat weighs about 8000lbs dry and runs about 87.5mph GPS with a full tank of fuel (30" Bravo One lab finished props). By the way, my hull has a pretty good HOOK in it that I need to have removed and I am still playing with props.
I prefer the low maintenace of the hydrualic roller cams vs a solid/mechical roller or flat tappet cam. This purely my preference for the reasons I like. If you want as low of a maintenance engine as you can possibly make it then the hydraulic roller cam/lifters are the way to go. Just don't go past the 5800rpm limit.
Your heads are fine but, as Bobby Daniels has mentioned, they are not up to the full port work that Mikehtmsr24 and I have had done to our aluminum heads plus we are running a little more comp ratio than you.
Here's an experience a friend of mine (Doug AKA "Pure Adreniline") went through about a year ago. He has a 35' Cigarette with a pair of 540's with new World Products 308cc cast iron heads with bowl port work done by "JimV", has the exact same cam as you are running, 9.0 comp ratio, 850cfm Holley carbs, dual plane intake manifolds and his dyno'd out at 595hp @5200rpm.
In his quest for more power, the following year he pulled one of the engines and put it on the same dyno, installed a larger cam(240*/250* at 50 lift) and the engine did NOT like it at all!---At least that is what the dyno numbers were telling him. I think Doug told me that it didn't even make the power the previous cam he had in it even by advancing/retarding the cam and I think they even tried a Dart single plane intake with it as well. Whatever the reason was, the cam change wasn't worth the switch, so they re-installed the cam he previously had in it.
Maybe Doug will see this post and chime in here.
Also, I suspect the magazine did NOT have anywhere NEAR a full tank of fuel in that boat when it was tested for the article!
Last edited by KAAMA; 06-01-2003 at 03:20 PM.
06-02-2003, 06:58 AM
#42
By the way, please understand I am not trying shoot down anyone's suggestion---it's all good input and at least the wheels are turning.
I cannot remember the exact differences between the two cams that showed up on the engine when it was on the dyno. There are a lot of variables and every engine combination is different. However, I thought Doug's engines and Caveman's engines are close enough for an interesting compare. Doug's heads definately had bowl work done on them by JimV for sure. Doug's 850's and Caveman's 1050 carbs are a considerably different in size----perhaps that may be why the larger cams didn't work for Doug. (???)
What do you guys think?
I cannot remember the exact differences between the two cams that showed up on the engine when it was on the dyno. There are a lot of variables and every engine combination is different. However, I thought Doug's engines and Caveman's engines are close enough for an interesting compare. Doug's heads definately had bowl work done on them by JimV for sure. Doug's 850's and Caveman's 1050 carbs are a considerably different in size----perhaps that may be why the larger cams didn't work for Doug. (???)
What do you guys think?
06-02-2003, 07:49 PM
#43
Registered
Thread Starter
Kaama,
Your comparison is a excellent one infact I beleave the merlin heads that are on these 540s are the smaller 308cc
heads. I called world products and they are unable to tell me via the casting numbers which exact heads they are. Due to the age of the heads 1992. The last trial run I topped off the fuel tank so that it would be fair to the previous run. Bobby D refers to the cam as being to small to pull past 5100. With the head cam combo he`s right. I am leading to replace the heads with a set of
AFRs or Dart pro ones. I would like to choose a cam that would be friendly to supercharging. There is also the saying if it aint broke dont fix it. The Summers are way to short in New England to start pulling things apart in beginning of June .
However Todays fastest Run is the follwing days slowest.
Your comparison is a excellent one infact I beleave the merlin heads that are on these 540s are the smaller 308cc
heads. I called world products and they are unable to tell me via the casting numbers which exact heads they are. Due to the age of the heads 1992. The last trial run I topped off the fuel tank so that it would be fair to the previous run. Bobby D refers to the cam as being to small to pull past 5100. With the head cam combo he`s right. I am leading to replace the heads with a set of
AFRs or Dart pro ones. I would like to choose a cam that would be friendly to supercharging. There is also the saying if it aint broke dont fix it. The Summers are way to short in New England to start pulling things apart in beginning of June .
However Todays fastest Run is the follwing days slowest.
06-11-2003, 08:12 PM
#45
Donzi33ZX
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Join Date: Mar 2001
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My only question for your prop guy is.
How is "RAKE" added to a prop?
Additionally, "cup" only lowers RPM, and does nothing for the preformance of a prop.
Bryan
How is "RAKE" added to a prop?
Additionally, "cup" only lowers RPM, and does nothing for the preformance of a prop.
Bryan
Last edited by Bryan Tuvell; 06-11-2003 at 08:17 PM.
