More Prop advice please Suzuki DF140

[JohnnyMW]

Hi everyone had my Vipermax ( with Suzuki DF140) on the water for the first time yesterday at New Brighton on the Wirral. Fantastic day but it raised a prop question. I've currently got a 14x21" aluminium prop and yesterday managed a WOT 5500rpm and speed of 35knts. I realise reducing the pitch will increase max revs but should I risk going to 14x18" to get theoretically 6100revs and increase speed or is this too big a jump?

[matt h]

that would be about right

[boristhebold]

35 knots at those revs sounds fine. Look at the manual for that engine and see what rev range it states as top end to see if feasable. you might allready be in the ideal wot rev range so exceeeding might put too much wear and stress on engine and components.

[JohnnyMW]

I've read that max revs for the DF140 are in the range 6000-6200 so thought I might be able to get some more top end speed by reducing the pitch. That is right??

[A1an]

You are only looking to gain 500rpm, will it make that much difference to the top end?

Do you run flat out all of the time? Are you actually likely to use your extra couple of knots?

[Maximus]

Originally Posted by JohnnyMW

Hi everyone had my Vipermax ( with Suzuki DF140) on the water for the first time yesterday at New Brighton on the Wirral. Fantastic day but it raised a prop question. I've currently got a 14x21" aluminium prop and yesterday managed a WOT 5500rpm and speed of 35knts. I realise reducing the pitch will increase max revs but should I risk going to 14x18" to get theoretically 6100revs and increase speed or is this too big a jump?

With that engine/hull combo I'm sure there is more performance to be had.
I'd Try speaking to other VM owners to see what they run...and what performance you can expect before spending out!
Once your confindent of what May be achieved ...it might well pay to get a SS prop in the chosen size,and keep your present one as a spare

[Maximus]

Originally Posted by matt h

that would be about right

Yeah right!...frightened of the competition!?

[Nos4r2]

500 rpm off peak HP is quite a lot.

[JohnnyMW]

Originally Posted by Nos4r2

500 rpm off peak HP is quite a lot.

That's my point, peak power according to Suzuki is at 6000rpm with max of 6200. My 14x21" aluminium prop is giving me 5500, so dropping 2" of pitch should bring the rpm up. If I go stainless the only option with an OEM prop is to go 14x20 or 14x18. The 18" just seems a big jump and at £300+ and expensive experiment. Maybe just go for the 18" and have it cupped if necessary. Any Vipermax 5.85m owners out there who can help?

[Mollers]

Ah, just spotted that it's a 5.8.

DHD has a 150 Opti on his 5.8, that'll pull almost 47knots.

Roycruse had a DF140 on his RC585 running a 21P SS prop, that would hit 41knts.

I'd expect your rig to achieve somewhere near the 40knt mark.

[69cmw]

What about lifting the engine up 1 hole? Should rev higher that way and go quicker.

[Daniel]

I'm no prop expert but don't you go up an Inch in pitch when you swap from Ali to stainless to theoretically keep similar performance ??

[Johnscubanut]

I believe if you drop down to an 18inch ally prop you should be able to increase revs by around 750. I was told for every inch of pitch, you increase or decrease by 250-300 rpms. Stainless steel is slightly different tho because of the thinner steel. So going for a 21 inch stainless prop you would actually be using around a 19-20 inch pitch prop. Does this make sense anyone or am I just talking b******s?

[pow2gran]

Johnny

Below is a link to the suzuki website re prop size and also attached is a test report relating to a RC585. The details in the report reflect the performance that I get on my RC585 with a DF 140 and a 3 x 14 x 21 inch prop

My Suzuki - Prop Shop | Suzuki GB Marine

Top revs is 6000 and we have had our top speed of 42knots coming out of the swellies with a full tank and 2 up. The fuel consumption is as per test report. This is on a 2006 engine.

It would seam that you are running a little low on rpm at 5500. I am no expert but it would appear that the prop size is Ok so is the engine at its optimum on the transom. Cost nothing to try a notch higher or lower just the hassle of moving the engine.

I have been tempted to put a stainless prop on. I had a stainless prop on my old tohatsu but have resisted changing to a stainless on the DF140 after having a few dicussions. If you ding an ali prop it is supposedly more forgiving and as result there is less risk of damaging the gearbox in the lower leg.

Shall we see you in N Wales?

Nick

[JohnnyMW]

Originally Posted by pow2gran

Johnny



Below is a link to the suzuki website re prop size and also attached is a test report relating to a RC585. The details in the report reflect the performance that I get on my RC585 with a DF 140 and a 3 x 14 x 21 inch prop



My Suzuki - Prop Shop | Suzuki GB Marine



Top revs is 6000 and we have had our top speed of 42knots coming out of the swellies with a full tank and 2 up. The fuel consumption is as per test report. This is on a 2006 engine.



It would seam that you are running a little low on rpm at 5500. I am no expert but it would appear that the prop size is Ok so is the engine at its optimum on the transom. Cost nothing to try a notch higher or lower just the hassle of moving the engine.



I have been tempted to put a stainless prop on. I had a stainless prop on my old tohatsu but have resisted changing to a stainless on the DF140 after having a few dicussions. If you ding an ali prop it is supposedly more forgiving and as result there is less risk of damaging the gearbox in the lower leg.



Shall we see you in N Wales?



Nick

Hi Nick,

Thanks for the comprehensive reply the RC report is fantastic what service. I've read about lifting the engine and will have a look at this as a means of getting the revs up. I've got a Suzuki 3x14x23" aluminium too, but think I'll put that up for sale and use the proceeds to contribute to a stainless prop! Speed and max rpm isn't the be all, but just fancy having the option. I'll let you know how I get on!

You will certainly be seeing me in North Wales next season and probably over the winter/ Christmas too- weather permitting! I've got the bug 👍😃

Cheers

Johnny

[jeffstevens763@g]

jonny

i have a 90 Suzuki on a 6m rib-quest with a 14 x 19 Ali prop i get 39 knots flat water no wind or tide @ 5800 rpm.
with a powertech prop 13.5 x 21 stainless steel roughly the same.
with a 14 x 20 stainless steel it drops the revs around 500 rpm and around 30 knots top end.
two people up 70 lts of fuel 20 kg of kit.
you could speak to Dave rose at rib-quest his brother in law has done quite a bit of prop calcs on a 140 Suzuki on a red-bay 6m.

hope that helps

regards jeff

[JohnnyMW]

Originally Posted by jeffstevens763@g

jonny



i have a 90 Suzuki on a 6m rib-quest with a 14 x 19 Ali prop i get 39 knots flat water no wind or tide @ 5800 rpm.

with a powertech prop 13.5 x 21 stainless steel roughly the same.

with a 14 x 20 stainless steel it drops the revs around 500 rpm and around 30 knots top end.

two people up 70 lts of fuel 20 kg of kit.

you could speak to Dave rose at rib-quest his brother in law has done quite a bit of prop calcs on a 140 Suzuki on a red-bay 6m.



hope that helps



regards jeff

Thanks Jeff

It is a real minefield, pitch, diameter, engine height. It would be nice if there was someone out there offered a service to effectively tune your rib to optimise performance!

I will post what I try and the results but intend cracking this one over the winter- it's a good excuse to get out there!!!

Cheers

[jeffstevens763@g]

johnny

spoke to Dave at rib-quest for you the trouble is that its not an exact science and lots of factors come into it he recons speak to power-tech they are in the game and will give you best info.

regards jeff

[JohnnyMW]

Originally Posted by jeffstevens763@g

johnny



spoke to Dave at rib-quest for you the trouble is that its not an exact science and lots of factors come into it he recons speak to power-tech they are in the game and will give you best info.



regards jeff

Cheers Jeff I'll speak to power-tech!

Johnny

[jeffstevens763@g]

Powertech stainless steel and aluminium propellers from Propeller Solutions powertech dealer

regards jeff