Suzuki DF140 Jet
I posted this as a response on another thread, but my interestest was peaked and I am now looking for some input or opinions. I have a Suzuki DF140 and after reading some posts about it, I started wondering?????
The Suzuki DF140 power head has a gear reduction. This reductions ,obviously, reduces the RPMs at the shaft. This is what got me to investigate. I started looking at the the outboard jets website, http://www.outboardjets.com/index.php . I may be wrong, but It appears that the Suzuki DF140 is spinning a larger impeller (7 5/8") than most, in its class. The impeller size is more along the lines of larger HP engines (175-200). Is the gear reduction why it spins the larger impeller? Is this an advantage or not?
Suzuki DF140 7 5/8" impeller
Yamaha 115 & 150 - 7 3/8" impeller
Mercury 115 Opti 7 3/8" impeller
Honda 135/150 7 3/8 impeller
I do not know the pitch of these impeller. It is quite posible that some of the ones rated for more HP, are pitched more aggressively.
Anyone who knows anything about outboard jets, please review this data and give me your opinion. I may not even be reading all this data correctly.
Last edited by akjeff; 03-08-2009 at 19:22.
I dont know the pitch of the impeller either, but am fairly certain the gear reduction is the reason for the larger impeller. The jet unit is like a "displacement pump" and in order to get adequate water volume through the unit, Outboard Jet choose the bigger pump to get the job done.
I doubt it is really an advantage, a smaller pump turning faster and moving the same amount of water would do the same thing.
Do you have a jet on your 140?
I generally concur with AKgramps on this performance wise. I will add that there may or may not be a bennefit in the fuel burn. A head to head test on several identical boats would be the only real way to test it definatively.
Yes I do. I run a 24' ATEC Hydrolite. With an 02 DF140 jet.
Originally Posted by Akgramps
What is your experience with this setup? power and fuel economy?
Originally Posted by akjeff
How wide is the bottom on your ATRC?
I have one (actually Johnson 140 made by Suzuki) on a 20 foot boat and I think the performance and economy are excellent.
I had a Honda 50 prop (w/ jet...that I never assembled) the OB Jet installation instructions included instructions to remove and replace the Honda reduction gear. just FYI
My Yami JET included no such verbage.
I'm pretty sure impellor diameter is just based on how many ponies you've got to spin it. I wouldn't consider leaving any (RPM) reducing gear in place if you're converting to JET
I have been running this setup for two years now, 09 will be my third summer. The model is a 2472. So I believe it has a 72" bottom. The beam is 95". With the boat being so big I find it easy to overload. It is equipped with a hydraulic jackplate and I have a couple lower units and 1/2 dozen props (for the Yukon). Performance wise; I can always use more power, especially when running heavy during moose season. A bit big for the Little Su, but lots of fun when running light.
Originally Posted by Akgramps
The gear reduction is built into the powerhead, so no eliminating that, suzuki is the only one to do so. They did that with props in mind, the theory is it alows them to turn a larger prop, which has more bite than a smaller diameter. In order to get the same gearing otherwise would require a much larger lower end and hence more drag.
Originally Posted by ref+10
Outboard Jet decides which pump to use depending on a number of factors. Because the pump is not spinning as fast as it would be on a comprable HP motor of another brand, they must have felt it best to use the big pump on the 140. To my knowledge that is the only motor in that HP range using the super pump.
I have heard the Suzis can dyno out at over 145, no idea if thats true or not?