05' Suzuki 115 top speed and RPMs

[montanabay]

Hi All,

I was reading some test boat stats on the Suzuki 115 and noticed that similar weight boats were getting up to 42mph @ 6000rpms with the stock stainless steel prop(SS 3blade, 14/22)

http://www.suzukimarine.com/boat_bu...ina_skiff/sea_chaser_1800_roll_gunwale/df115/.

When I run my Western Eagle Skiff 18' (similar specs to Sea Chaser 1800 Roll Gunwale) I usually top out at 5500rpms and 33mph (2 guys, 1/2tank, light gear), which makes we wonder if I'm running lean or not getting enough gas to the engine? Its not a huge deal, since running the boat @ 4500 is the most fuel efficient and comfortable ride, but that last few dead calm days when I could run flat out...well I didn't seem to run flat out. How does your boat perform with the Suzuki 115?

Also, I have a powerlift and have played with the prop depth and trim, same top-out.

Looking at my fuel line to my large RANCO, it looks to be 1/4" line, but the motor is rated to 3/8", enough difference? What does are symptoms of an engine not getting enough gas at higher rpms?


Cheers,

Josh

 

[reeldutch]

Re: 05' Suzuki 115 top speed and RPMs

i guess you have a df 115?


it should be propped at 6000 rpm.


you have a fuel injected 4 stroke, running leanis what its all about. not like a old carbed 2stroke.

only fuelpresure and duration of the injectors is how fuel is being metert by the ECM.


if you have a dirty injector you wil have performance problems like poor idle rough running power loss.

did it ever run faster than 5500?
it should be propped at 6000.
what size prop do you have?
14X22?

is the anti ventilation plate even or higher than the bottum of the keel?
is the hull in good condition?

 

[montanabay]

Re: 05' Suzuki 115 top speed and RPMs

i guess you have a df 115?


it should be propped at 6000 rpm.


you have a fuel injected 4 stroke, running leanis what its all about. not like a old carbed 2stroke.

only fuelpresure and duration of the injectors is how fuel is being metert by the ECM.


if you have a dirty injector you wil have performance problems like poor idle rough running power loss.

did it ever run faster than 5500?
it should be propped at 6000.
what size prop do you have?
14X22?

is the anti ventilation plate even or higher than the bottum of the keel?
is the hull in good condition?

yup its the DF115, definitely never got it up to 6000rpms, bought it used with 9hrs on it (did the 10hr service), only ~60hrs total right now.

Injectors should be pretty clean, limited hours on the boat. Idle is fine too, can barely hear it and no vibrations.

I'll have to check the vent plate, the boat has a pretty shallow draft with a 1/2 transom, so its mounted pretty low to begin with. I really need to mark it on the powerlift so I can get the height right after bring it up and down in the shallows.

I do notice that when it is all the way down on plain it sprays a lot of water forward on the sides of the engine.

 

[reeldutch]

Re: 05' Suzuki 115 top speed and RPMs

so make sure its even or slightly higher than the bottum of the keel.
than use the engines trim to get all the rpms it will make. if its less then 6000 you should consider a different prop.
what prop do you have on it right now?

 

[montanabay]

Re: 05' Suzuki 115 top speed and RPMs

thanks for the advice, I always judged the prop height by bubbles for cavitation, never thought about the anti-vent tho.

I believe it is the stock SS 14/22 3 blade.

Here is the boat: The Eagle 180, self bailing skiff style, haul is only 950lbs, draft 12" and half transom on the back and super wide, beam is 7'6". The engine is a little heavy for it too, makes the back sit a little low, but not that bad. I bet I have the AVP too low.

http://www.danblanton.com/westerneagle/specs.htm#spec

its 95% fishing boat, no need for skiing or anything, usually fish with 2-3 guys, limited gear.

Conditions in the SF Bay are usually pretty choppy, so I don't get to run it flat out often, 23-24mph is usually comfortable in the 1-2fters.

What prop would you recommend? This is new to me, grew up with a 25hp on a 16ft Lund!

Thanks,

Josh

 

[montanabay]

Re: 05' Suzuki 115 top speed and RPMs

yup, AVP was too low, brought the powerlift all the way up, rpms hit 6000, boat hit 43mph

wonder why they put the powerlift on it at all, engine can only go deeper from the best WOT position.

 

[reeldutch]

Re: 05' Suzuki 115 top speed and RPMs

good to hear it worked out.
i dont know why they put it on i gues to make some money?

good luck

 

[stylesabu]

Re: 05' Suzuki 115 top speed and RPMs

montanabay, post yor question in the section on props.read some of the other posts. it was very helpful for me to reach top speed for my boat. there are some very helpful people here.