What is your GPH at WOT with your engine?

[SeaKaye12]

Note to JB... I realize that this is not technically a repair topic...but since I have a Merc...and am interested in other peoples experiences with Mercs...I hope you can allow this post to remain in this forum. If not...of course I understand ...Chuck<br /><br />Someone here said that there is a rough formula to determine if one's fuel consumption is within the norm.<br /><br />If someone knows various formulas...please post them. But, better than that...post what engine or engines you have...and what your WOT GPH is...<br /><br />If you know; that is... <br /><br />Heck...if you don't know....here's an excuse to take the boat out with some gas...and run her at WOT for an hour... <br /><br />Ther's a lot worse ways to spend an hour; eh?<br /><br />Thanks guys...I learn so much here...thank-you to all of you! Chuck

 

[andy6374]

Re: What is your GPH at WOT with your engine?

Don't know exact number, but i know my 88' V6 200hp Black Max loves her fuel. On long trips, 20miles+, I run her a 4000RPM or else i will really empty my pockets

 

[ctoolman]

Re: What is your GPH at WOT with your engine?

the smart guage tells me 15.5gph per motor..i have twin 150 opti's on a 23 ft boston whaler outrage...needless to say,i don't run WOT much...<br /><br />thats like 90.00 per hr to run that way..sorry i don't make that kind of cash per hr..<br /><br />3500 rpm range gives me 5.0gph per motor and about 26-27 mph but still all my trips are short hauls..

 

[Perfidiajoe]

Re: What is your GPH at WOT with your engine?

I just recently installed a Flo-Scan on my boat, It's a 21' Wellcraft, I have a '95 225 XRI w/ aprox. 525 hours on it. I had it out today, light load, just me, about 40 gal. of gas, no other extra weight. I opened it up for a minute, it went to 6100 rpm's, then I guess the limiter brought it down to 5800 the pre-set max, the Flo-Scan said 26 GPH, ouch, I don't do that too often. I usually run at about 1/2 speed 3000 to 3400 Rpm,s depending on the prop I have on, at about 12 gph.

 

[Silvertip]

Re: What is your GPH at WOT with your engine?

It depends on how hard you run and how heavy the load is but for most engines, drop the last digit of the horsepower and you will be quite close to the gallons/hour.<br />Therefore a 50 HP will burn 5 gal/hr. 150 HP roughly 15 gal/hr. Gets you in the ballpark. The numbers given in previous posts prove this.

 

[Clams Canino]

Re: What is your GPH at WOT with your engine?

Those that run WOT for an hour deserve what you get <br /><br />My 150 uses about 8gph at 3900 rpm (26mph)<br /><br />You math types can figure out exactly how much gas volume it could suck through three .080 main jets at WOT.<br /><br />-W

 

[danie]

Re: What is your GPH at WOT with your engine?

Agree with Clams.<br />I run wot for 10 minutes and multiply by 6 to get usage per hour.

 

[Nos4r2]

Re: What is your GPH at WOT with your engine?

I get about 5gph from my 50- but most of that is in rougher seas than most of you guys will see and it's spending a lot of time on/off the throttle.Very little's at WOT. It has a HARD life when it's running like that and I've got to be a good boy as I can only carry 13 gallons.<br /><br />On the few occasions I've had it out on flat water it uses an awful lot less fuel-3gph(ish) at 2/3 throttle and 26mph.

 

[stan_deezy]

Re: What is your GPH at WOT with your engine?

Gee's it just shows you: I learn something everyday I look at iboats: upinsmoke I never heard that formula before but when I started to think back on all the engines I have run it works very well indeed:<br /><br />Mariner Magnum 4 Cyl; WOT 4gph<br />Evinrude 25; WOT 2.5 gph<br />Mariner 3.3 WOT ah well, almost works <br /><br />But yeah, thats a pretty good formula, thanks,

 

[robalofish]

Re: What is your GPH at WOT with your engine?

1994 200HP carbed with Flow-scan<br /><br />Idle = 3-4 GPH<br />2000 RPM = 8 GPH<br />4400-4500 RPM Cruise = 12-13 GPH<br />WOT 5600-5800 = 24-25 GPH <br /><br />These are average with medium load.

 

[Silvertip]

Re: What is your GPH at WOT with your engine?

Stan -- I'll bet the formula works for the 3.3 as well. Just move the decimal point one spot to the left. .3 gal/hr will be pretty close. That's the same technique as dropping the last number in double- or triple-digit hp ratings.

 

[gss036]

Re: What is your GPH at WOT with your engine?

I don't run a flow-sacn, but I very much agree with RobaloFish. I have run my 1989 Merc 200hp since new and had it figured at 10-12 gph@4200 depending on the wind&water(closer to 12 most of the time). You just cannot squeeze any more out of the old carbs.

 

[stan_deezy]

Re: What is your GPH at WOT with your engine?

Actually upinsmoke: you are spot on! The 3.3 uses around 0.5 gph at WOT but it was trying to shift a 16' Boston Whaler style boat

 

[swist]

Re: What is your GPH at WOT with your engine?

While the formula is close for 2-stroke engines at WOT, it is very hard to predict what it is for minimum cruising speed - could be significantly lower. Also a "formula" for 4-stroke or DFI engines would be useful.

 

[Silvertip]

Re: What is your GPH at WOT with your engine?

Swist -- The formula applies to four strokes as well. Here are numbers from Yamahas web site (performance bulletins) for a 90, 75, and 60 HP engine all on an Alumacraft Navigator 165 CS. These are Yamaha's numbers -- not mine.<br /><br />90 HP = 8.2 GPH<br />75 HP = 7.5 GPH<br />60 HP = 5.2 GPH

 

[swist]

Re: What is your GPH at WOT with your engine?

So what's the story with 4 strokes supposedly consuming much less fuel? Or is it the case that at WOT all engine types consume about the same, the difference being at cruise RPMs?

 

[SeaKaye12]

Re: What is your GPH at WOT with your engine?

Good question Swist...<br /><br />The numbers are scary; eh?<br /><br />I know boating isn't cheap...but seeing the reality of fuel consumption in black and white like this is a bit dis-heartening. <br /><br />What can I do to cheer me up? Well...I'm going out in the boat!<br />Chuck

 

[Perfidiajoe]

Re: What is your GPH at WOT with your engine?

Good idea, go out in the boat! After all gas is as cheap as it ever will be. I'm going too!

 

[Silvertip]

Re: What is your GPH at WOT with your engine?

It is no mystery. It takes so much fuel to make so much horsepower at wide open throttle. If you look at the low and mid range rpm figures (where available) you will see the DFI two strokes and four-strokes have an advantage. The percentages thrown about by the manufacturers seem significant and in numerical terms they are. But if one engine burns 10 g/hr and another burns 8, thats 20% less but in the grand scheme of things, unless you run hundreds of hours per season, you will likely never recover the premium for DFI or Four-stroke technology. Its emissions that are driving technology, not fuel economy. But that's all a moot point as you will very shortly be unable to buy a carbed two stroke new. Looking at it another way, my departed Mother many years ago complained like crazy about fuel economy when she traded her six cylinder Chevy for a V8 Oldsmobile. My response to her was Mom, you drive well under 5000 miles a year -- what's your point (and that was when fuel was 49 cents a gallon).

 

[Fastjeff]

Re: What is your GPH at WOT with your engine?

My 360 cube Crysler V-8 marine engine burns 8 GPH at 2,500 rpm cruise, and about 10 GPH at 3,000 rpms. Not sure the hp. developed at part throttle, but this is a 275 hp.engine at 4,400 rpms.<br /><br />Jeff