Best 4 stroke for my 5.4 f Signature

[MikeC90]

Thanks for the feedback Col. I believe the 125 is essentially the same but with different carb jetting? Is yours also running a vented prop? Seems to be something Merc came up with to suit 2-strokes with a narrow power band, not really used anymore. Mine has none of the tuning plugs in it and the local Merc dealer reckons they can't get them anymore. I think tuning it for a bit less cavitation at slow speeds would help but still going to be awkward with the 2+2 setup... I imagine it'd be a nightmare for bar crossings and big swell/chop, with not being able to module speed properly down low.

I think the performance is quite okay for the hull, gets up on plane in 5 seconds or so and tops out over 60km/h with 4 adults + gear. I don't have much to reference against though...

Yeah, all of the current offerings in the 115-140hp category have pros and cons. I like the 'keep it simple' design mentality of the Merc 115 and they have good low-end performance by all accounts, especially with the CT gearbox. The Merc 135 would have oodles of grunt but really its pushing 220kg for the XL shaft with oil and prop - nearly 60kg more than the current engine! The Suzi 115/140 appear to have really good reliability and economy, plus the 2.59 gear ratio allowing for 14" props, should give plenty of options. The Yamaha 130 would likely have the best dealer support with where I live and is light for the power but I think they look and sound pretty ordinary, plus I'm always a bit wary of timing belts.... It also irks me that they claim it to be a 'new engine' when it's clearly a 115 with some tweaks. Then the Etec G2 115HO/140 also have plenty of appeal. I like the design ethos and they seem ahead of the game with the electronic controls and integrated trim/steering. 5 years/500 hours without needing a dealer service is also very convenient and would account for many $$$ over that period.

I feel like the 4-stroke options are all about due for an update too, being 5+ years old and missing some of the features that Evinrude has introduced at that price point. Hopefully I'll get a few years of reliable service out of the old girl anyhow!

[blacklab]

Yeah, I ruled out the Yam 130, purely because it's the old 1.8 block, just tricked up, mind you, that's exactly what Suzuki has done with there reliable and successful 140. There's no replacement for displacement, the old saying.
I don't know a lot about etecs, but there was something about certain servicing proceedures still had to be carried out, and I thought that 500 hour was only for fresh water use ? I could be wrong there.
The torque from my old 125, was fricken unbelievable, off the mark you held on, BUT, in saying that it was changed to all the time 4 cylinder. you really felt the limiter come in though at 53-5400 revs, but she pushed my old cruisey along at just under 70 kph, and to be honest, you just never drive the boat at that speed anyway, just trolling in the swell was a pain at lower rev's.
220 kg on the back with that 135 merc, is a big step up in weight, a mate has the 150 on the same boat as mine, and you seriously have to make adjustments weight wise,,,, and in all honesty, on a glassed out day, pushing 80 kph, was a thrill, but overkill.
The command thrust 115 pro XS, seems to be the bees knees, plenty of torque down lower for bar crossings and getting up on the plain and also pretty well the same weight as my old 125 2 stroke. I'm not knocking the 140, I'm considering it still, but every boat I've been in, from Barcrushers, Evolutions, Signatures etc, they just seem under whelming as far as performance,,, not reliability. I'm not after a boat that touches near 80kph or even 70kph, I wouldn't use it, but I'm picking the 4 stroke merc would match your 115, or better.......
Being that mine is smaller than those I've been in with the 140, I'm assuming I would get better performance, that's why it's still on the cards, but is heavier by 10 or 15 kilos thatn the merc.. still cant understand why people match 6 meter fibreglass with the 140, a mates 6 meter signature, struggles on a glassed out day to get near 60 kph !! But, he has done quite a few hours and years with it, just can't afford the upgrade....
Keep ya old smoker going as long as you can, it's not cheap to upgrade, or get permission to shop for a new 4 stroke ...

Col

[Andy56]

When i had my 543rf sig, I had an etec 130hp( 4 cylinder) and whilst it did move ok, I was seriously contemplating a 150etec, (before the divorce) I went out in a similar boat with a 115etec and a 140 suzi 4 stroke and to tell the truth not much in it. If you want just a little more, go to the 150hp range, you get a serious wack of power increase. Etec gen2, 150 and 5 years non service,( i guess with some kind of small print). and any other 4 stroke 150 would be a better fit than less power.

[blacklab]

Agree Andy, BUT, an extra 50 kg's swingin off the back, out of hull rating, doesn't work to well.
Sometimes it's just a case of getting the best all round match. It's nice to have that extra grunt, but on a 5.4, it would never be used......

Col

[MikeC90]

Andy, with 2 x 50-60kg people on the rear seat she's pretty bum heavy... With another 50-60kg of Merc 135 right out the back I think she'd likely need tabs to work properly. No doubt that extra torque would be nice but I'm not sure it would balance out (pardon the pun) the extra weight and fuel consumption. The Etec 135HO (G1 V6) is listed at 196 kg (not sure if that includes either oil tank) and is probably the highest performing outboard that would legally go on the boat. Again, likely overkill for my needs, but if I could find one of those I'd consider it...

Col, I'm thinking much the same as you, in that I don't need the ability to do 70-80km/h. Don't get me wrong, I love fast cars and do track days etc, but in a boat with kids, 65km/h seems plenty fast enough when conditions allow. My main performance consideration would be hole-shot, as I think water sports will be on the agenda once the kids are a bigger - also useful for certain sea conditions. With that in mind, the Merc 115 CT Pro XS or Suzi 140 with the low gear ratios and big props would be the front runners. Etec G2 115HO or 140 should, on paper, be very strong down low as well.

I guess it's the same as cars, no substitute for actually testing them!

[Andy56]

if you dont really care about outright performance, then anything in the 115-140hp range is going to be similar. If you then find its a bit short on ponies, put a smaller prop on.. your not going to get much if anything beyond 60km/hr anyway. your not going to miss out on economy or reasonable power.

[stevej]

Merc use a 3.0l block for their 135 Suzuki 2.3l

And there are variables across the whole range of brands and hp from 115 to 140

You really have to do your homework on random weight v hp v capacity

To say a 3.0 l isn’t going to perform any better then a 2.0 even though the sticker says the same hp is just rubbish

[blacklab]

Steve, the Suzuki 115 and there 140, is the same block, barely a 2.1 lite ( from memory )

A common problem on smaller boats, around the 5.4-5.5 size, the 3 ltr versions are just to heavy....
But yes there's no comparison between any of those 3 ltr engines compared to any 2 ltr version, night and day...

Col

[stevej]

Yep as i said its a balancing act of the many variables but a mate has a 3l merc and the pick up is amazing

[blacklab]

They are a machine Steve, awesome motor.
As I mentioned above, a mate of mine put the 150 Merc on the same boat as I have, when the Merc first came out, but it's just too heavy, the shagging around weighting it down in the bow, and getting it balanced properly, he said it's an awesome motor, but if he had it over again, he would have just slapped the 115 on, it effectively was overkill and doesn't really get any benefit on a 5.4 mtr hull,,, apart from a glassed out day and pushing 80 kph for fun.
I think it's just that size hull bracket, up to 5.4 ish, where the hulls rated for less, I know mine is rated to a max 150 hp, but that's the old 2 stroke weights, and a boat that size, that's 30% above hull rated max with a 4 stroke. I think boats 5.5-5.6 mts and above have far bigger options in regards to the 3lt 4 strokes, they can take the weight.
In saying the Merc 150 is a great engine, I went on a mates boat it was under 6 meters, it had the 150 Suzuki on the back, now that packs some puch as well. As you said, it's a big step up from the low 2 ltr blocks to the 3lt puppies.......

Col

[Dirtyfuzz]

As I have mentioned in a previous post I repowered the old Kevlacat which would weigh 2.5t maybe more loaded and the torque from the twin 115ct with 14x19p props still amazes me, did a run out to the hards a few weeks ago, 25 knots heading there in a choppy head sea and 37 knots back used 120l for a 140km round trip, very happy with the purchase!


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[blacklab]

Yes I saw when you posted up on the new engines, great to hear there performing for you.
It will probably be the way I go, in the Pro XS model, since there's on one on mine.......


Col

[gazza2006au]

As I have mentioned in a previous post I repowered the old Kevlacat which would weigh 2.5t maybe more loaded and the torque from the twin 115ct with 14x19p props still amazes me, did a run out to the hards a few weeks ago, 25 knots heading there in a choppy head sea and 37 knots back used 120l for a 140km round trip, very happy with the purchase!


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geez sixty litres per engine for 140km's times really have changed soon we will be able to soak a rag zip tie it over the air filter to get 20km's....

2.5t boat that is quiet a load too

[Dirtyfuzz]

Weight was being conservative, On weighbridge was 3t no fuel no gear so add 360l of fuel, 3 passengers with gear, ice etc take off 700kg for trailer it’s probably closer to 3t


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[bden]

I have the slightly larger and beamier 550c matched with a 150 Mercury 4 stroke. I think for the 540 the lighter the better so 115 Mercury pro or Yammy 130 maybe should be in your short list


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