View Full Version : motor and prop gurus

10-05-2009, 06:14 PM
well its happened the 250 etec has been sold and the 300 Suzuki is on and its been blowing its head of since . after running around i mean crawling for 4 hrs in the ski pond it was taken out and put up against some rough weather as well as slowing cruising in the creek.

the etec swung a 15.5 x 17 while the 300 zuk swung a 16 x 18.5

the first most noticeable effect is the lift time of the 4 litre Suzuki it
is about exactly the same as the 250 etec , not bad for a fourstroke swinging a larger dia

the most beneficial thing that stood out was the zuk held the boat up far better at slower speeds in a heavy sea with or with out tabs

the most surprising thing about the fourstroke is the motor at idle is so quiet all you can hear is the tell tale hitting the water.

i rang my 20 hp honda kicker motor and it is far noisier than the zuk . it is a very quiet motor overall full stop.

i don't yet have the engine management system for the Suzuki to the lowerance system but it does work out that at 25 knots cruising in a sea i am doing the same overall revs as the etec . it seems the extra pitch and lower geared motor are cancelling each other out.

question if this is so would not the Suzuki be giving better fuel economy as it fires every second time rather than once for the etec even though the etec is 3.2 l compared to 4 l

top end is higher but this is immaterial as its to different horsepower motors .top rpm at present is 6100 rpm at present which is close to the 6300 limit. i have placed 8 people on board plus 350 litres of fuel , 60 ltrs water and fishing gear and she lifted it without any body having to come forward . would you go to the 19 pitch or stay with the 18.5 . after all it is a heavy tub. we usually come home from the reef with four on board and most times the 300 litre esky very heavy. i haven't owned a large fourstroke before and is it so important to reach maxium rpm like the etec or do you let them lug a bit more by swinging the 19 and dropping back to maybe 5800 or so .

ideas and thoughts greatly appreciated.



10-05-2009, 07:44 PM
the most beneficial thing that stood out was the zuk held the boat up far better at slower speeds in a heavy sea with or with out tabs




This is the thing you will notice most with the four, in a sea you'll find your not on and off the throttle as much as a 2 stroke ( any 2 stroke) Running downhill you'll find it wont skip aways as much down the wave and wont drop back as much going up the back of the next. This is by far the best feature of a fourstroke at sea , yes they dont have the same zip but propped it correctlty and you'll be suprised. On props there's not alot in it but on the figures you gave i might go with the 19.


10-05-2009, 07:51 PM
I did notice your boat has a bladder problem.
Sorry I cannot be of any more help other then that. :(

10-05-2009, 08:08 PM

IMO you will get way better fuel economy with the 18.5 than the 19 when you get a 4 stroke to rev close to the limiter its performing at its peak. The more you bring those max rpms down the harder it is working.

It will be good to here your fuel usage differences have had both DFI and 4 stroke on the same hull.

How is the engine height??

10-05-2009, 08:16 PM
Agree with Gary go up until it shouldn't go up any more, then whatever RPM is left to gain get a prop man to tickle it, 19p is simply out of the question unless also reducing diameter but then you may loose some of the things you said you liked.

cheers fnq

10-05-2009, 08:18 PM
yeah guess who forget to drain the kill tanks , hopefully the cable wont be to long in coming.

Luke G
10-05-2009, 09:24 PM
Suzuki don't make a 19. I'd throw a 20x16 on there and see what happends. They'll let you swap props over for free until you find the right one.

It'll loosen up after 60 odd hours too.

11-05-2009, 07:19 AM
the engine height is dead on i purchased the xtra long model and used a jacking plate . reason was the motor was a$1200 dollars cheaper. ozzy dollarr . anyhow it has worked out good as it keeps more of the upper out of the water. the jacking plate only keeps the motor out a further 12 mm . remember i had the engine height to go by off the old motor which was on the upper edge .



the motor balances out pretty good by the picture .that includes the 20 hp Honda on the other side as well . lucky as well as engine height when tilted is not a problem.

chop duster
11-05-2009, 11:11 AM
The four stroke injects more fuel, less often - compared with the 2 stroke. hope this makes sense, couldn't be stuffed to go into more detail right now.

Scott nthQld
11-05-2009, 03:11 PM
Graham, I don't think you'd get much better than what you have on it already. With a motor just broken in getting 6100rpm, and 50mph (yes I mean miles not knots) currently at full noise. For the moment I would wait until the motor loosens up a bit and see what the rpm is then, if over 6300, then get a new prop (don't ask me what, I'm definitely no guru).

I thought it got out of the hole great guns, I even thought it was a little quicker than the etec too, but as you say...you can't beat cubes.

I reckon you will see an improvement of fuel figures though, though etec's get well publicized about their economy they were always a little heavier on the juice than a 4str in the same class. Even though you've gone up 50hp and .8l capacity, also take into account the extra hp and capacity will also mean the engine won't be working as hard, pushing the same load, plus you won't be using any oil. so even if fuel economy is the same, you'll be effectively saving about $30-$40 per trip in oil alone AFTER servicing has been taken into account, and that's without considering the cost of service for the etec.

on that last comment I'll elaborate, before the etec fans get a chance on a rebuttal.

Graham used to use approx $70 in etec oil per reef trip, doing 5 hours per trip
a 4str uses no oil

4str servicing every 100 hrs, so on Graham's usage, 20 reef trips
20 reef trips by $70 oil for the etec is $1400 per 100 hours
100hr service on 300hp suzi, roughly $7-800
so thats a $6-700 saving per 100 hours comparing a 250 etec and 300 suzi

I've no idea what a service on an etec that size costs, but I'll hazard a guess at around $5-600.
Anyone you takes care of their boat, and goes offshore regularly (well you can't exactly fish in a creek out of a 680 Patriot (trust me, we tried) will, for safety's sake get their outboard services at 100hrs intervals at least, no matter what the manufacturer says.

Taking this into account every 100 hrs:

250 etec uses:
$1400 oil
$600 service (for arguments sake we'll use the upper limit)

= $2000 every 100 hrs

300hp suzuki uses:
$0 oil
$800 service

= $800 per 100 hours

so including servicing there's around $1200 in savings to be made per 100 hours So even if the suzuki uses an extra 5ltrs an hour more (though I highy doubt it will), at today's fuel prices (of 105.9 just down the road from me) the suzuki will only be using $105.90 more in fuel, still leaving Graham $1100 per 100 hour in front.

The only figure I had a guess at in those was the Etec servicing, though graham will be able to shed some light on that further if he wishes.

11-05-2009, 06:33 PM
Hi Scott,

That is interesting info re the oil burn/cost per trip. I'm amazed it is that much.

Graham, great looking rig that looks even better with the Suzuki hanging off the back. Will be interested to hear how it performs over time.


11-05-2009, 06:48 PM
yes your figures are right scott the large etec motors over 4 000 rpm tend to drop back to around 60 to 70 to 1. the new 300 etec uses even more so its nearly back to that old 50 to 1 . it must be noted not once did that motor ever leave me in troubles at the reef . its not a bad motor just that i have found something better.

Scott nthQld
11-05-2009, 07:18 PM
yeah I agree, they are a good reliable motor, but saying that so are the suzuki, why else would they have a 7 year warranty, shows a lot of confidence in their product IMO. I was just looking at things from running and maintenance cost point of view.

Not bagging the etec's reliability, but others are just as reliable that cost less to run.

And yes the big Haines looks oh so sexy with the new donk