osd9
New Member
Looks like from a fuel efficiency standpoint that you are about the same over the range from ~3200-3800 RPMs
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Correct... as the GPH goes up, the Speed goes up in equal ratio. Look at the power band curve earlier in the post, the 3-4k RPM range is right in the sweet spot for torque on this engine as well. It's all connected...:thumbsup:Looks like from a fuel efficiency standpoint that you are about the same over the range from ~3200-3800 RPMs
When I purchased my '04 270SD the HO upgrade required the B3X because the B3 max hp was 400hp. I don't know how long it had been that way but it is still that way now. B3=400 hp max, B3X=450hp maxA lot of stuff flying around.
Unless Merc changed something, the original Bravo III's were rated at 450hp and shipped with both 502's and 496 HO's.
The 8.1's are in fact full of car parts.... OK truck parts. The internals are from GM and are the same as in a pickup. Previously Merc would switch to forged components in the 454 Mag (385hp) and 502 Mag (415hp). The 496's and standard 454's have the same components (crankshaft, connecting rods, and pistons) as a pickup. I have heard conflicting information regarding the heads (from Mercruiser), but suspect they are the same.
Performance guys are not big on the 496's because bumping output via supercharger has a high tendency to break them. The 454 Mags and 502's could take supercharging very well. In fact Merc's 525 SC was just a supercharged 454 Mag.
As far as fuel consumption, the 496's will take about 14 GPH at 3200, if propped to reach 4800 at WOT. They'll draw 32ish at 4800.
Reading what I wrote so far, it sounds as if I don't like the 496's. I do. That was the reason I bought my 310. they are good motors. Smooth, quiet, good power, (exceptional midrange in the standard 496 which is great for a cruiser). The roller cam, 8 coil ignition, and 8 channel fuel injection really has a lot to do with the smoothness and midrange of the 496. But I prefer the toughness and simplicity of the 454 Mags and 502's. And of all the motors, the 502 did a great job of being strong throughout the entire RPM range.
And of all the motors, the 502 did a great job of being strong throughout the entire RPM range.
JVII, the 502 I was refering to preceeded the 496.
I think I would call it a new engine. Auminum heads, changes in pistons and rings(the 502s of the past had oil use issues). http://www.brunswick.com/news/newsstories/release/1/1324095.phpRoger that, but the 496 was replaced with a 502. I wonder if the new 502 is that same basic architecture as the old 502 with ergonomic tweaks, software, and catalytic converters. If so, definitely a worthy successor of the 496, sans the catalytic converters.
Skuza
What speed are you making cruising at 3200rpm? TeamSeaRay - same question to you. 17800lbs sounds high for a 2000 340DA. Not nitpicking but if your boat is truly that heavy (dry), you're pushing the limits for "all day."
It's been a long winter but if memory serves me correct I'm thinking 3,200 gets me 22-24 knots (~24-26mph). The 400 dancer was reported to be 22,500lbs but wonder if that was with diesels?