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496HO fuel consumption

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Discussion starter · #22 ·
Swamplizard said:
for $450 you can get a navman depthometer and two fuel flow meters - put them in line and plug the wires into the depthometer and you have fuel consumed, gph,mpg in real time.
Click to expand...
Perhaps, but GPH is only a fraction of what this SW tells you. Most importantly, trouble codes. Plus, more things that I feel like typing here. It's a diagnostic tool, I didn't buy it for the sole purpose of finding out my fuel consumtion.
 
#24 ·
Super24 said:
I come up with about 10-12 GPH pretty consistantly. This is a mix of idel, cruise, and wot.
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I must spend way too much time in no wake zones. My average over the last four seasons is right around 12 gph. (I know because I keep all my gas receipts for fuel tax refund.) That is for twin HO's. :p:
 
#25 ·
Super24 said:
For the owners of 496HO's. Ever wonder how much fuel your motor burns? Now that gas is so expensive, I'm trying to find that "sweet" spot. Using Diacom software this was my findings from today.

RPM GPH
700 1.61
750 2.0
850 2.17
1070 4.26
1525 5.67
2000 8.55
2100 9.22
2200 9.57
2400 10.43
2800 10.55
3000 11.67
3300 14.5
3500 16.49
3800 19.51
3900 19.73
4000 21.17
4100 22.98
4500 29.26
4600 30.1
4700 32.21
4800 33.32
4900 33.64
4950 34
Click to expand...
looks like 3000 rpm is your sweet spot...
 
Discussion starter · #26 ·
Re: Re: 496HO fuel consumption

revx440 said:
looks like 3000 rpm is your sweet spot...
Click to expand...
Going strictly by the math that is true. But, my boat doesn't seem to like riding at 3000. My prop doesn't feel completely hooked up. Also, my bottom has a pad and I don't feel like I am up on the pad like I should be.
 
#27 ·
Dave,

Great info on the GPH. I have my throttle marked where the secondaries open using my everyday prop (big difference in GPH once they open up). It is very fuel efficient with 82 primary jets, behind the mark.

If you feel like you are slipping at 3000 and not up on the pad this may be worth looking into for a Bravo props. Several guys on the Potomac have used this design and it is scanned and blueprinted at Murphy's Propeller in Norfolk. I only say this because there was alot of trial and error until it was right for most V bottoms like ours. I can not take credit, Ed Clarke spent all time and money getting it right.

I found that the prop has alot to do with how it rides as much or more as the RPMs. I had a couple of my props sent down to Murphy's in Norfolk and had the tips skewed as well as thinned. Since I am running a 2" shortie drive, I was not carrying the bow high enough. I was running flat more like a cat does. The boat would tend to bow steer at higher speeds/RPMs as the transom lifted along with the bow. Instead of spacing the drive down and using more trim, the prop design took care of it and allowed me to ride up on the pad at a lower RPM.

You are welcome to try my 26 Bravo with this lab.

Ty
 
Discussion starter · #28 ·
Good info Ty. I'm running a 28 Bravo right out of the box. I had a prop done by Murphy's several years ago. It was the Mirage Plus that my boat came with. I later discovered that a Mirage + is just not the prop for my boat.

Other than the 28-3200 range, I don't have any issues. I'm turning the 28P right at 5K rpms, it stays hooked up, my bow lift is good, and I don't think I need any stern lift. I guess it wouldn't hurt to try the prop you mentioned and see if it helps the low rpm ride.

See you on the River!
 
#30 ·
twin 502s at about 425 carbed....I get about 2.4 gph per motor at 900 rpm for a lousy 1.36 mpg at nowake speeds.

Not sure about the rest since I am having problems with my trim but I am assuming around 40 gph at 35 mph

SLLLLLLLUUUUUUUUUUUUURRRRRPPPPPPPPPP
 
#32 ·
I have had my 496HO since 2003 after re-powering my 239 Glastron Ultra.
I thank you for the data, I have always assumed that the 3000 rpm rage was the sweet spot and your data pretty well confirms that. What prop are you spinning? for those numbers. I am spinning a 24 Bravo, but have a 25 Mirage plus and a 27 mirage for long distance cruising.

Razz
 
Discussion starter · #33 ·
Doctorrazz said:
I have had my 496HO since 2003 after re-powering my 239 Glastron Ultra.
I thank you for the data, I have always assumed that the 3000 rpm rage was the sweet spot and your data pretty well confirms that. What prop are you spinning? for those numbers. I am spinning a 24 Bravo, but have a 25 Mirage plus and a 27 mirage for long distance cruising.

Razz
Click to expand...
I'm spinning a stock 28P bravo 1, 1.5 gears, up to 5000 RPMs
 
#34 ·
3000 rpm is pretty much the sweet spot for fuel economy [ gph , totally regardless of what boat it is ] and between 3200-3700 is best for mpg according to the ton of infos of magazines I've collected over three decades . Carburated engines with 4 barrels have the secondaries still closed around 3000 , hence the best economy at that rpm . Fuel injected engines seem to have the best economy at 3000 as well . I have SmartCrafts with my twin sbc's and the reading are pretty consistent like Shameless stated with his .
 
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mirage257
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