80 mph 24'
09-07-2007, 02:51 PM
#31
I was just giving Pat a hard time. If two motors have the same hp curve then they have the same torque curve, regardless of cubic inches. But, generally a 502 will have more hp AND torque in the mid-range over a 454 and that is what Pat was saying.
09-07-2007, 03:03 PM
#32
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Most Bravos are 1.5 and that really doesn't come into play because you can go up or down in prop pitch to adjust accordingly.
I was just giving Pat a hard time. If two motors have the same hp curve then they have the same torque curve, regardless of cubic inches. But, generally a 502 will have more hp AND torque in the mid-range over a 454 and that is what Pat was saying.
I was just giving Pat a hard time. If two motors have the same hp curve then they have the same torque curve, regardless of cubic inches. But, generally a 502 will have more hp AND torque in the mid-range over a 454 and that is what Pat was saying.
I prefer hp engines with higher rpm, I would like to see 6000 vs. 5800. But that's my car background coming out.
I know I'm splitting hairs here, and it really doesn't matter, but would a 454 550 hp vs. 502 550 hp, be more efficient? I also want to stay around 8.75 to 9:1 comp so I can us regular unleaded...
09-07-2007, 03:12 PM
#33
so you're saying... "There's no substitute for cubic inch..."
I prefer hp engines with higher rpm, I would like to see 6000 vs. 5800. But that's my car background coming out.
I know I'm splitting hairs here, and it really doesn't matter, but would a 454 550 hp vs. 502 550 hp, be more efficient? I also want to stay around 8.75 to 9:1 comp so I can us regular unleaded...
I prefer hp engines with higher rpm, I would like to see 6000 vs. 5800. But that's my car background coming out.
I know I'm splitting hairs here, and it really doesn't matter, but would a 454 550 hp vs. 502 550 hp, be more efficient? I also want to stay around 8.75 to 9:1 comp so I can us regular unleaded...
A 454 that makes 550hp at 5800 rpm will have less torque than a 502 that makes 550hp at 5200rpm. Regardless of cid higher revving motors of equal hp make less torque. And boat motors need torque.
09-07-2007, 03:13 PM
#34
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Rob, I can do better than $5,500 on my 525 and you'd be able to recoup some of the cost by selling off the motor you have now (thanks for the plug Stormrider!). The thing runs good, but it's not the right motor for me. I have the opportunity to run for extended periods of time at WOT with that motor (based on the mid 60's speed it will push my 28). So I decided to get something with a bit more heat so that I can run 65 further down in the RPM range. The 525 was perfect for the rivers and lakes that Griff ran it on.
80 is my goal but I'd be satisfied with 75 too. 75 is nothing to sneeze at.
What's a 454 worth, new heads, intake, cam, somewhere bw. 330 and 375 hp?
09-07-2007, 03:22 PM
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RPM kills valvetrains. RPM is expensive. It's about efficency though. Any given motor is going to have an optimal operating range. So the key is to find a motor with a optimal range consistent with the application's parameters.
As OSP mentioned, HP is really a function of RPM and Torque (can't remember the formula, but that's what the internet is for, eh). Seems like, in a boat, the operating parameters dictate more torque in a reasonable range of RPM operation (3,500 - 6,000 I'm guessing). My small block makes peak power between 7,500 - 8,200 rpms. But that's because it doesn't have much torque!
As OSP mentioned, HP is really a function of RPM and Torque (can't remember the formula, but that's what the internet is for, eh). Seems like, in a boat, the operating parameters dictate more torque in a reasonable range of RPM operation (3,500 - 6,000 I'm guessing). My small block makes peak power between 7,500 - 8,200 rpms. But that's because it doesn't have much torque!
09-07-2007, 03:29 PM
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My rule of thumb on pricing used stuff is about 50% of what it would cost to buy it new.
I've heard that with the 24s, 75 is a nice quick ride and 80+ will turn your hair white (unless your last name is Nunez
).
Mine only ran low - mid 60s so it was no sweat most of the time. Flat out, trimmed out with a good bump going, you did feel like you were really driving the thing!
I've heard that with the 24s, 75 is a nice quick ride and 80+ will turn your hair white (unless your last name is Nunez
).Mine only ran low - mid 60s so it was no sweat most of the time. Flat out, trimmed out with a good bump going, you did feel like you were really driving the thing!
09-07-2007, 03:32 PM
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RPM kills valvetrains. RPM is expensive. It's about efficency though. Any given motor is going to have an optimal operating range. So the key is to find a motor with a optimal range consistent with the application's parameters.
As OSP mentioned, HP is really a function of RPM and Torque (can't remember the formula, but that's what the internet is for, eh). Seems like, in a boat, the operating parameters dictate more torque in a reasonable range of RPM operation (3,500 - 6,000 I'm guessing). My small block makes peak power between 7,500 - 8,200 rpms. But that's because it doesn't have much torque!
As OSP mentioned, HP is really a function of RPM and Torque (can't remember the formula, but that's what the internet is for, eh). Seems like, in a boat, the operating parameters dictate more torque in a reasonable range of RPM operation (3,500 - 6,000 I'm guessing). My small block makes peak power between 7,500 - 8,200 rpms. But that's because it doesn't have much torque!
I'd say may application would be cruising mostly at 30-45 mph with an occasional WOT blast, to knock off a couple of bow riders and jet boats etc...lol Running 80 mph across a 5 mile wide lake, I'd be across the lake in little over 3 minutes...
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09-07-2007, 04:12 PM
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I knew that there was an rpm number where the hp and tq were always equal due to the denominator, but I couldn't remember the number!
Oh and Rob, a house isn't near irrational enough to desensitize her!
Oh and Rob, a house isn't near irrational enough to desensitize her!
