The 39 Rockit with 725 Ilmors and Indy drives hit 115 mph
04-16-2010, 07:45 PM
#21
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Don't confuse torque at the crankshaft with torque at the propshaft. If the Merc 700 makes it's power at 5250, then it has 700 ft-lb at the crank. If the Ilmor makes 725 at 6300, then that's 605 ft-lb at the crank. If the Ilmor uses a 1.5 drive and the Merc a 1.25, then the Ilmor wins at the prop: 908 ft-lbs at 4,200 versus 875 ft-lb @ 4,200 rpm.
Where the Merc has a potential advantage is under acceleration. If Mercury chooses to up the boost in the mid-range, the power curve can be fattened up as much as they want.
Ain't competition grand?
Where the Merc has a potential advantage is under acceleration. If Mercury chooses to up the boost in the mid-range, the power curve can be fattened up as much as they want.
Ain't competition grand?
04-16-2010, 07:57 PM
#22
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As delivered stock - the ilmors put more power to the props than the Mercs for 2 reasons and are much lighter.
Back to the power.
Dustin Whipple himself has dynod multitudinous merc 6 and 700's and according to his dyno they do not make the factory rated power. The Merc 525 consistently makes more like 545 but the blown mercs dont.
Ilmors dont come off the dyno till they rate-its their policy.
Combine this with the Indy drives lower parasitic loss than the NXT's and the Ilmor package wins out of the box.
Uncle Dave
Back to the power.
Dustin Whipple himself has dynod multitudinous merc 6 and 700's and according to his dyno they do not make the factory rated power. The Merc 525 consistently makes more like 545 but the blown mercs dont.
Ilmors dont come off the dyno till they rate-its their policy.
Combine this with the Indy drives lower parasitic loss than the NXT's and the Ilmor package wins out of the box.
Uncle Dave
04-16-2010, 08:13 PM
#23
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Curiosity:
What does the each package cost, Ilmor v. Mecury, complete with drives and headers? I like the V-10's. I just really don't know what the price difference is, just wondering.
What does the each package cost, Ilmor v. Mecury, complete with drives and headers? I like the V-10's. I just really don't know what the price difference is, just wondering.
04-16-2010, 08:17 PM
#24
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I am definately not an expert on the Ilmore engines and I am sure someone will chime in on your statment to back me up or back you up here but,
the Ilmore's are 8.4L or 511 cu in. engines while the 700sci's are 8.2L or 502 cu in. While that is pretty close, displacement is a big contributing factor in torque production.
Both are overhead valve engines, and both are pretty close in displacement. The big difference seems to be the Merc uses a supercharger to make similar numbers to the Ilmore and the Ilmore uses 10 cyl vs. 8
So for you to say the Ilmore's are down on torque compared to the 700sci which requires a supercharger to make its power doesn't seem to make sense to me.
A naturally aspirated engine will generally make its torque at a lower rpm and maintain it longer than a super, or turbo charged one. At least that was always my understanding.
Again, could be wrong.
the Ilmore's are 8.4L or 511 cu in. engines while the 700sci's are 8.2L or 502 cu in. While that is pretty close, displacement is a big contributing factor in torque production.
Both are overhead valve engines, and both are pretty close in displacement. The big difference seems to be the Merc uses a supercharger to make similar numbers to the Ilmore and the Ilmore uses 10 cyl vs. 8
So for you to say the Ilmore's are down on torque compared to the 700sci which requires a supercharger to make its power doesn't seem to make sense to me.
A naturally aspirated engine will generally make its torque at a lower rpm and maintain it longer than a super, or turbo charged one. At least that was always my understanding.
Again, could be wrong.
04-16-2010, 08:25 PM
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04-16-2010, 09:07 PM
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04-17-2010, 07:00 AM
#29
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GPS is all that matters...the rest is just all hype. This boat tops does 108 tops with a high X.. Prove me wrong.....
04-17-2010, 07:12 AM
#30
Sadly John from Hustler is more hype than anyone in the boat business (Reggie must have passed on some tips to him last year). On the other Hustler thread he was very proud of "the dividends" of his nutty ad campaign and how his "crews are the only ones in the boat business working 40 hour weeks." Yet when I specifically asked how many of the 39 Rockits he has built/sold over the last 2 years (since they are the best, fastest boat out there right now) all I got was silence much like this thread when the GPS was requested.
