More Prop advice please Suzuki DF140

[JohnnyMW]

Originally Posted by jeffstevens763@g

Powertech stainless steel and aluminium propellers from Propeller Solutions powertech dealer

regards jeff

Hi Jeff

Have spoken to power tech who suggest I try raising the engine a notch or 2 and then try some fast tight turns ( as fast as I dare) Apparently as soon as the engine starts to cavitate in a tight turn you have the right engine height. This should bring the revs up, but most likely I will also need a 19" pitch SST prop for an Osprey 5.85 to hit the 6000 rev sweet spot! Powertech reckon I should get 40-41knts max but beyond that will compromise performance in the poor weather! Will try and raise the engine a notch!!

Cheers

Johnny

[jeffstevens763@g]

hi jonny

that makes sense suppose that's why hydraulic jacking plates are used to give that vertical trim for optimum performance.

good luck

cheers jeff

[JohnnyMW]

Here's the update - looked at the engine height on the transom which seemed perfect with the cavitation plate bang in line with the keel. So bought a Solas HR3 SST 13.7/8" x 19" prop. Fitted it yesterday and had the WOT revs up to 6100 and managed to get her up to 40.1knts but consistently 39.5! Pleased but think I might try raising the engine a notch just to see what happens.

Thanks for all of the advice!

[Cypman]

I had similar issues with a Suzuki DF 140 on a Humber Ocean Pro 6.3 and ended up with the same prop and top speed as you are now achieving. Don't expect to replicate speeds being achieved by other manufacturer's 150 hp outboards (or even Suzis DF150) as the DF 140 is believed to only produce circa 126 bhp at the prop. Nonetheless, it is a fantastic engine, light and very economical.....enjoy.

[Cypman]

I had similar issues with a Suzuki DF 140 on a Humber Ocean Pro 6.3 and ended up with almost the same prop and identical top speed as you. Don't expect to replicate speeds being achieved by other manufacturer's 150 hp outboards (or even Suzis DF150) as the DF 140 is believed to only produce circa 126 bhp at the prop. Nonetheless, it is a fantastic engine, light and very economical.....enjoy.

[Maximus]

Originally Posted by JohnnyMW

Here's the update - looked at the engine height on the transom which seemed perfect with the cavitation plate bang in line with the keel. So bought a Solas HR3 SST 13.7/8" x 19" prop. Fitted it yesterday and had the WOT revs up to 6100 and managed to get her up to 40.1knts but consistently 39.5! Pleased but think I might try raising the engine a notch just to see what happens.

Thanks for all of the advice!

Six knots from a prop change is pretty good!
Worth trying the engine height while you're messing about I suppose but that IS a good gain....is new the prop SS or another Ally?

[Mollers]

Originally Posted by JohnnyMW

Hi Jeff

Apparently as soon as the engine starts to cavitate in a tight turn you have the right engine height.

Go careful on that one. A notch too high and a handful of helm and she'll hook like hell.

You're already now pretty close to the best that combo is gonna achieve.

[Mollers]

Originally Posted by Maximus

Six knots from a prop change is pretty good!

Astonishing. Either it was a previously prop'd as a tug, or someone chucked a random on to get rid.

[Newto]

Originally Posted by JohnnyMW

Here's the update - looked at the engine height on the transom which seemed perfect with the cavitation plate bang in line with the keel. So bought a Solas HR3 SST 13.7/8" x 19" prop. Fitted it yesterday and had the WOT revs up to 6100 and managed to get her up to 40.1knts but consistently 39.5! Pleased but think I might try raising the engine a notch just to see what happens.

Thanks for all of the advice!

I would give it a go, I think the shape of the hull also plays a part, with a deep V the cav plate can be higher than the bottom of the hull.
Mine is about 1 1/2 inches above but cannot go any lower without cutting.
I suffer a bit of cavitation when turning tight but can live with it as it runs very well otherwise. I will have a tinker with props when I get hold of a couple.
My setup is 5.1m, 90 ETEC with a 13 1\4 X 17 prop, had 3 adults today and managed flat out 36mph at 4600 revs.
Any views on this setup?
Thanks in advance.

[JohnnyMW]

When I spoke to Powertech they suggested a 19" pitch SST prop. They also suggested increasing the engine height 1 or 2 notches and then doing some tight turns as fast as you dare - apparently as soon as you start to get cavitation you're at the right height so it sounds like you've got it just right! I forgot the tight turn bit this weekend but next time I'm out I'll give it a whirl. Powertech said the max speed I would get would be 40-41knts so maybe I there already!!

I daren't tell the wife I need a bigger boat with a bigger engine just yet :-)

Anyway have 2 Suzuki props that are now redundant, both Aluminium 14", one 21" and the other 23" pitch - so if anyone interested?

[Pikey Dave]

Duplicate post

[Pikey Dave]

Duplicate post, "Database error" grrrr!

[Pikey Dave]

Originally Posted by Newto

I would give it a go, I think the shape of the hull also plays a part, with a deep V the cav plate can be higher than the bottom of the hull.
Mine is about 1 1/2 inches above but cannot go any lower without cutting.
I suffer a bit of cavitation when turning tight but can live with it as it runs very well otherwise. I will have a tinker with props when I get hold of a couple.
My setup is 5.1m, 90 ETEC with a 13 1\4 X 17 prop, had 3 adults today and managed flat out 36mph at 4600 revs.
Any views on this setup?
Thanks in advance.

If you are only getting 4600rpm at WOT, you are way over propped. You need to see another 1000rpm. That prop looks a bit steep for that rig, I would have thought a 15" tops, which should gain you another 400 rpm, even then you'd be borderline.

[Hightower]

Originally Posted by JohnnyMW

When I spoke to Powertech they suggested a 19" pitch SST prop. They also suggested increasing the engine height 1 or 2 notches and then doing some tight turns as fast as you dare -

You don't have to do "fast" tight turns to check for cavitation during turns. Set your trim at the usual level (trimmed out) and set a course at say 20kt's then do a starboard and port progressive hard turn. As your RIB tilts over it'll lift the prop towards the surface. If you suffer with no cavitation I would lift one hole and try again until you start to lose grip in the turn (engine revs rise and speed drops off). You might find that either Port turns or Starboard turns suffer more more from cavitation than the other. This is because your outboard is probably off-set to port or starboard depending on whether you have a CW or CCW rotating gearbox.

Once cavitation is experienced I would then try the turn again at the same speed but with the engine trimmed in. If you can turn without cavitation and loss of grip then I would say that you're pretty much at the height you want to be at. If you are still suffering with cavitation I would go down a hole and stick with that.

[JohnnyMW]

Originally Posted by Hightower

You don't have to do "fast" tight turns to check for cavitation during turns. Set your trim at the usual level (trimmed out) and set a course at say 20kt's then do a starboard and port progressive hard turn. As your RIB tilts over it'll lift the prop towards the surface. If you suffer with no cavitation I would lift one hole and try again until you start to lose grip in the turn (engine revs rise and speed drops off). You might find that either Port turns or Starboard turns suffer more more from cavitation than the other. This is because your outboard is probably off-set to port or starboard depending on whether you have a CW or CCW rotating gearbox.



Once cavitation is experienced I would then try the turn again at the same speed but with the engine trimmed in. If you can turn without cavitation and loss of grip then I would say that you're pretty much at the height you want to be at. If you are still suffering with cavitation I would go down a hole and stick with that.

I was thinking I should try raising one hole to see what happens thanks for the advice. I've noticed with the Vipermax that the rear end of the tubes sit quite low on the water, pretty much up to the rubbing strake even when moving at 20knts. Is this unusual or is this another indication that the engine is too low?

[Newto]

Originally Posted by Pikey Dave

If you are only getting 4600rpm at WOT, you are way over propped. You need to see another 1000rpm. That prop looks a bit steep for that rig, I would have thought a 15" tops, which should gain you another 400 rpm, even then you'd be borderline.

Yes i did think that as the spec says 5000-5500 for this motor, I did have 3 adults onboard and 70l fuel but I will try and drop to a 15, I was just not sure to buy one or try and lend one. I plan on taking the kids out in the summer on a donut so would you think a 15 would be ok for this?
Cheers!
Gary

[Pikey Dave]

Originally Posted by Newto

Yes i did think that as the spec says 5000-5500 for this motor, I did have 3 adults onboard and 70l fuel but I will try and drop to a 15, I was just not sure to buy one or try and lend one. I plan on taking the kids out in the summer on a donut so would you think a 15 would be ok for this?
Cheers!
Gary

Before shelling out on props, I'd make sure that the engine is setup correctly first, as it's the cheaper option. You need to ensure that when the throttle is at maximum travel, the throttle plates are fully open & the TPS is at WOT voltage. Ideally you'd use a laptop with the diagnostic software to do this, but iirc it can be checked with a multimeter. Propping is a bit of a black art, but generally speaking 1" of pitch = 200rpm or thereabouts. So dropping 2" should gain you 400rpm ish. Also switching from an ally to stainless prop will get you about another 100rpm for the same size prop.

[Newto]

Originally Posted by Pikey Dave

Before shelling out on props, I'd make sure that the engine is setup correctly first, as it's the cheaper option. You need to ensure that when the throttle is at maximum travel, the throttle plates are fully open & the TPS is at WOT voltage. Ideally you'd use a laptop with the diagnostic software to do this, but iirc it can be checked with a multimeter. Propping is a bit of a black art, but generally speaking 1" of pitch = 200rpm or thereabouts. So dropping 2" should gain you 400rpm ish. Also switching from an ally to stainless prop will get you about another 100rpm for the same size prop.

Sounds a bit much for me, how would I setup up to use a muntimeter?
The engine is 2009 model only done 35 hours. I do have a full engine printout from the dealer just before I bought it would this info help?
Thanks for your help Dave.
Gary

[Pikey Dave]

Originally Posted by Newto

Sounds a bit much for me, how would I setup up to use a muntimeter?
The engine is 2009 model only done 35 hours. I do have a full engine printout from the dealer just before I bought it would this info help?
Thanks for your help Dave.
Gary

If it was setup by a decent dealer, then all should be well, I'd assumed it was a self install. Has it been serviced since new? if not, it's due & all the checks will be done as part of the service. If you post up the engine report I can have a look. Look on the report for "TPS Calibration" the number should be 190 +/- 30 so between 160-210

[Newto]

Originally Posted by Pikey Dave

If it was setup by a decent dealer, then all should be well, I'd assumed it was a self install. Has it been serviced since new? if not, it's due & all the checks will be done as part of the service. If you post up the engine report I can have a look. Look on the report for "TPS Calibration" the number should be 190 +/- 30 so between 160-210

Cheers Dave ill get that sorted for tomorrow I dont think it was serviced because the chap I had if off bought it Dec 2008 and it was due first service Dec 11 but so very little use. It was showing 32 hours when tested in November just gone.
Gary