Fuel Consumption...Some data

djredman99

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#1
As some of you have seen, I started a thread not too long ago inquiring about gas consumption. I have collected a bit of data and had some time today to put some info out there.

I used several sources, all of which tested with flow meters to accurately determine fuel usage. There really is a lack of good data out there with regards to this, but the best source I have found so far has been BoatTest.com. They give feedback on fuel consumption for the full range of RPMs on the machine and tell you what the optimum cruising speed is. However, they have only tested sporadically the PWC market over the last decade, so finding info on a particular machine is unlikely (they did seem to recently do the full 2011 Yamaha lineup).

Here are some findings on some of the 2009 PWC's. All numbers are in Gallons per hour (GPH). (Assume some +/- variable to these results)



I think the above graph is interesting as it points out that the RXT-X has nearly identical gas consumption as the GTI SE 130 when just cruising around at a modest 35 MPH. So, as long as you are not heavy on the throttle (yeah right) you should get pretty good gas usage. This is true for all of the models as they are all within 4 GPH of each other.

You can see what 15-18 extra MPH costs you as the RXT-X and high-end Kawi's and Yami's top speed approaches 70 MPH while the Yamaha VX and Seadoo GTI top speeds are 53 and 52 respectively.

Here is one with some of the top of the line models. Make note that the @65 MPH is used here and not WOT.



Keep in mind that Seadoo (and Kawasaki I think) recommend 91+ octane for all their top-end models where as Yamaha has an octane rating of 87, something they pride themselves on. You can use 87 in the high end seadoos without damaging the engine, but overall performance is decreased.

Something else that I have noticed is that the newest Yamaha lineup (2011) seems to have better fuel efficiency than the data present here.
 
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djredman99

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#2
Yamaha

For those interested, here is data from the 2011 Yamaha lineup.



The VXR is their stripped down, no frills, speedy 3 seater with a top speed of 68.4 MPH and gets very good numbers.
 
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djredman99

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#3
Carbureted Seadoo PWC's 1993-2005

Here is data pertaining to the 1993-2005 Seadoo carburetor models. These results are averages on the engine models, although, between the different hulls/models, the numbers only vary +/- a few decimal places. The source for this data is from somewhere I cannot list as it is blocked from this site, and I have checked the official specs published by BRP on these numbers as well.

Data is in Gallons per hour (GPH) at wide open throttle (WOT)



It is unfortunate that I could not come up with data for the @35 MPH range as well.
 
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djredman99

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#4
Late 1990's - Early 2000's Fuel Injected PWC Models

This data pertains to the 2-Stroke Fuel Injected models of Seadoo from 1998 - 2005. They only made two 2-stroke fuel injected engines during that timeframe, the 787 RFI and the 947 DI.

I've include specs for the carbureted models of those engines as well as reference. All numbers are gallons per hour (GPH at wide open throttle (WOT)

 
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djredman99

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#5
2002-2005 4-Tec PWC's

Here is the info on the Seadoo 4 stroke 4-TEC models. I added "by year" into this graph as the numbers change a little. The source for these numbers are directly from BRP spec sheets for these engines.

All numbers represent gallons per hour (GPH) at wide open throttle (WOT).




**As a final note**
Any mistakes you may notice for all the data in this thread or info on additional data from reliable sources is appreciated.
 
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SurfBeat

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#9
Fuel Consumption

GREAT ARTICLE.

Last fall after falling out of negotiations to purchase a couple bitchin' looking 96 GTX's, I purchased a couple 1997 Kawi's 1100 STX's.

One of my primary reasons for going Kawi rather than staying with SD was based upon all of the good reviews I read about Kawi's and the favorable comments I heard from owners of Kawi's. IMO, they also looked bitchin' when contrasted to other manufacturers. Remember, beauty is in the eye of the beholder, so, I am not chopping other manufacturers.

One major complaint I had about the SD brand was it required a more expensive oil, API TC rated in contrast to the type of oil other brands required - TCW-3.

Moving on and not related to PWC manufacturer, I wanted a larger gas tank because to my way of thinking at the time before the purchase, a larger gas tank meant a greater cruising rage.

The Kawi has a 14 gal tank and my 93 GTX's a small 8.7 gas tank. (The 96 S/D GTX's have a 15 gal tank)

Anyway, after my first couple of trips out to the River I quickly noticed that I liked the handling of my SD's because they were more agile. The loss of nimbleness may be based upon the fact that the Kawi's weight 135 lbs more than my 93 GTX's.

The major downside, however, was the gas consumption. Albeit the Kawi's gas tank was much larger than my SD's, my cruising range was about the same, approximately 60-70 miles at 25-28 mph, thus I realized no great benefit. The Kawi, at WOT will cruise for 1 hr and 9 minutes, one minute longer than a 96 GTX which has an extra gallon.

Learning that the Kawi's have three (3) carbs in contrast to the two (2) on the 96 GTX's (as well as my 1993 GTX's) I began to rationalize that the extra carb was the reason for the higher gas consumption. That thought turned out to be WRONG!

Since this is the SD Forum and not the Kawi Forum (I still have my SD's) out of curiosity I retrieved a 1996 GTX OG to compare to my 93 GTX Operators Guide and discovered that the 96 GTX has a 15 gal tank, however, at full throttle it will cruise for about 1.8 hrs whereas my 93 GTX with a 9 gal tank will cruise for almost one and a half hours.

I would have surmised that with a larger tank, the powers that be at SD would have made an engine that would cruise twice as far as the older engines. Maybe it is the weight and increase in hp?

Now, I know the OG's spec are listed for full throttle, however, even considering arguendo that I only cruise at half throttle, the variance will not be that much different.

The bottom line is clear; having a larger gas tank won't take you much farther than having one 1/2 that size. What a bummer.
 
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Dr Honda

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#10
Here is data pertaining to the 1993-2005 Seadoo carburetor models........

It is unfortunate that I could not come up with data for the @35 MPH range as well.
That's OK... it would only be relevant to the test ski, since there are HUGE differences in hulls and weights over the years. (ie... 720 engine in a 95 XP 2 seater @ 450 Lbs, Vs. a 96 Sportster 4 place boat at 1000 Lbs)

Great post. :cheers:
 
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#11
That's OK... it would only be relevant to the test ski, since there are HUGE differences in hulls and weights over the years. (ie... 720 engine in a 95 XP 2 seater @ 450 Lbs, Vs. a 96 Sportster 4 place boat at 1000 Lbs)

Great post. :cheers:
Although this is in the PWC forums, I should clarify, that ALL of this data is PWC's ONLY.

I used no data from any seadoo boats.

EDIT: I edited the post titles to specify it is PWC data where specific models were not referenced.
 
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spaldy

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#13
Thanks for the helpful information. As a NooB items like this are very helpful to understand what you might be looking at to
get across the lake to your favorite spot. Kind of embarrasssing to ask sometimes!
 

IDoSeaDoo

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#17
it seems that the 130 and the 155hp seadoos get the same economy at WOT, so why would anyone ever choose the 130 vs the 155? Does it get better cruising economy?
 
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#18
Most people equate wot =max speed= max gph but with a Sea Doo jet boat in the sport mode that's not so .
Weither you nail the throttle at 20 or 50 , with a Sea Doo jet boat your going to be at max fuel consumption in the sport mode most likely.
In general so long as the ecu inputs and outputs are not changing to fast , it can be somewhat precise in the amount of fuel it delivers.
If your going zero to sixty in 5 seconds for eexample , it has to go into the guess mode with the #1 priority being not allowing a lean state to exist . That means it must error on the rich side resulting in a spike in fuel consumption . So their are times even at 35mph , the blue line ,max gph is in effect .
 
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oztrax

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#19
Honda fuel economy

it seems that the 130 and the 155hp seadoos get the same economy at WOT, so why would anyone ever choose the 130 vs the 155? Does it get better cruising economy?
Don't won't to hijack this forum


But my 2006 F12X can get 10 LPH
Have got 5.5 hours out of 1 tank, obviously not at WOT
I reckon this is because at lower cruise speeds, the turbo boost is pretty low.
From memory only the Polaris is also turbo, all the rest supercharged.

Certainly at WOT which is over 90 kph , u can watch the fuel gage go down ;)


Regards
OZ
 

IDoSeaDoo

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#20
I wonder about adding trim tabs to my boat in regards to fuel economy. I've always though that they just add drag and increase wetted area. I compensate for bounce with jet trim. But the more i think about it, jet trim probably affects fuel economy more as it loads down the engine more directly. I can see the rpm drop when i trim down...
 

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