AD31p vs KAD32

I think if your engine is propped right, and producing the full 150hp and thats not enough, I suspect 170 will not make enough difference to warrant the cost.

I suspect a KAD42 would, or if budget allowed, D3 in 220hp tune would perform very well
 
QBhoy said:
To be fair. When I mentioned the 240 with the ad31 I was on...it was far too easy to try to compare it to the other 3 240/24’s I’d also experienced. Two had 4.3 V6’s (one a Mercruiser and alpha one and one a VP 4.3 with DP) and one had a rarely fitted VP 5.7 V8 and DP. There was a really noticeable difference in power and ability between them all I suppose. I’m sure most of the time...the ad31 150 would do the job well enough though.
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I think with most boats, a petrol version will be a faster boat. When I was looking to buy an S24, at Sealine I had a test drive of the petrol version (VP) and yes it was a faster boat, but I decided on the diesel as the performance was still very good and been happy with it ever since.
 
Petrol will be faster, and the newer MPi engines are better, but still a lot thirstier than a diesel. Gotta say, the new D3 engines are not far off the performance of the same power petrol, however much dearer.

Probably wouldn’t get the difference back in fuel saving, but the much higher resale would make a difference.
 
ontheplane said:
Probably wouldn’t get the difference back in fuel saving, but the much higher resale would make a difference.
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From what I have seen, boats that have been re-engined don’t tend to make a lot more because they are still the same age/model that they always were. Might get a bit of a premium and sell a bit quicker but unlikely to recover costs I suspect.
 
Scubadoo said:
Agree, I would be tempted to try J series (Eg. J5) duoprop which I heard some boaters had improve performance on acceleration, but lost a few knots top end which probably isn't an issue if you can improve the seawings 254 onto plane performance when loaded up.
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Many thanks for the suggestion. I will Defford look into props, but I think I have maybe not explained the issue very well. Getting on the plane, I am OK with. Its the top end speed with 4 up. I'm losing a good few knots and under certain conditions its dropping to like 15 or 16kts and needs more throttle to stay there you can tell she is just having to work real hard to keep from dropping to semi displacement.
 
ontheplane said:
Petrol will be faster, and the newer MPi engines are better, but still a lot thirstier than a diesel. Gotta say, the new D3 engines are not far off the performance of the same power petrol, however much dearer.

Probably wouldn’t get the difference back in fuel saving, but the much higher resale would make a difference.
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Yup not sure i want to spend that sort of money, plus all of the other stuff needed. Assume new wiring loom and outdrive, or at least gearing .
 
Greg2 said:
From what I have seen, boats that have been re-engined don’t tend to make a lot more because they are still the same age/model that they always were. Might get a bit of a premium and sell a bit quicker but unlikely to recover costs I suspect.
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Agree. Seen my boat advertised with and without kad32. Not a lot of price difference.
 
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I guess a lot depends on whether you can find a KAD32 for pretty much the same money you'd get from selling the AD, and whether you can do the swap yourself or need to pay someone else to do it....?

Possibly buy a boat with a KAD43 in it and swap engines then sell the "underpowered" one for river use??

All in all though seems more cost than benefit will warrant?
 
ontheplane said:
I guess a lot depends on whether you can find a KAD32 for pretty much the same money you'd get from selling the AD, and whether you can do the swap yourself or need to pay someone else to do it....?

Possibly buy a boat with a KAD43 in it and swap engines then sell the "underpowered" one for river use??

All in all though seems more cost than benefit will warrant?
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From my research will be about 3 to 4k
ontheplane said:
I guess a lot depends on whether you can find a KAD32 for pretty much the same money you'd get from selling the AD, and whether you can do the swap yourself or need to pay someone else to do it....?

Possibly buy a boat with a KAD43 in it and swap engines then sell the "underpowered" one for river use??

All in all though seems more cost than benefit will warrant?
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Kad32 tend to be approx 3 to 4k more than an ad31 from what I can tell. A lot if extra bits and upgrades to the ad31.
 
Crikey - then I'm thinking not worth it for 20hp - although I realise the supercharger will make a difference.

Is that relatively new from someone like Coastal Rides or similar?
 
We used to commission 31s and 32s with Volvo Watford and I was surprised how much more powerfull the 32 was, I was told that the spec for the engine allowed up to 190hp.
 
is that "up to" as in a large variance - or is that "it can be tuned to 190" or just that Volvo deliberately "misquoted" the power to sell more KAD42's ??
 
ontheplane said:
Petrol will be faster, and the newer MPi engines are better, but still a lot thirstier than a diesel. Gotta say, the new D3 engines are not far off the performance of the same power petrol, however much dearer.

Probably wouldn’t get the difference back in fuel saving, but the much higher resale would make a difference.
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My friend who berths in front of me, has a sealine SC29. She has twin D3 190’s in her. Apart from the silly idea of timing belts on a marine engine...must admit. Some serious power from those engines. That boat will charge along around 44 mph gps flat out. Fast boat, for her bulk. Fair play. I’m pretty certain that twin old school 190hp carb GM petrols wouldn’t manage that. But hey. I’m a fan of that D3 engine already. I have the same engine in my old XC90 tow wagon !
 
ontheplane said:
Crikey - then I'm thinking not worth it for 20hp - although I realise the supercharger will make a difference.

Is that relatively new from someone like Coastal Rides or similar?
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7k ish for a 32 seems to be approx the going rate I see out there for the few that come up for sale. And yes, I suppose relatively new if by relative we mean early 2000s.
Coastal rides can also do a full upgrade of a 31 to 32. Price works out similar.
 
stelican said:
We used to commission 31s and 32s with Volvo Watford and I was surprised how much more powerfull the 32 was, I was told that the spec for the engine allowed up to 190hp.
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I seem to hear more and more that the 32 feels a completely different beast to the 31 across the range.
 
Well yes, the Supercharger will make a massive difference - and if you had one putting out 190hp that would certainly feel very different.

What would worry me is spending 4k ish to only gain 20hp - albeit perhaps more grunt low down.

What would a KAD 42 cost - and what would you get for the old engine? I feel that is a more convincing upgrade although again, it's questionable whether you'd ever see a "return" on that - but if you enjoy your boating far more - perhaps it's worth it?

Then always with these topics, the next issue / question is .... what if you sold and went for a slightly different boat with the bigger engine in from the off - might cost more than 4k for sure - but perhaps that's the way to go.

Not sure there is ever a "Right or wrong" in this situation - merely what's "right" for you.
 
Just my tuppence worth here to add to it. I wouldn't suggest a 42 series engine for that as the extra weight in the back won't be offset by the increase in power. You will have to use a bucket load of tab just to keep it planing at lower speeds

The 32 is a completely different beast (as someone described it) to the 31 - it has so much more torque, and that torque comes in earlier. The only way you would get the benefit of the 32 though is if you changed the legs for the correct gear ratio too - then you would be able to use that torque. You can try it with prop sizes, but my best guess from memory (I used to manage a VP dealership) would be that you will be at the end of the prop size range and will be less than optimal.

I'm not personally convinced it's a viable upgrade, I just wanted to make the point that it's no just 20hp you are buying, and nor is it quite as simple as pulling out the 31 and dropping in a 32 then changing the props as that might not meet your expectation.
 
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