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Volvo penta aq151

I'm not so sure, my guess is you would need to find out how much room you have to work with in the engine compartment and kinda start from there. It would probably be similar to adding a supercharger to a Volvo B20 motor which I am sure people have done. Is it carburated?

Hi, yes it has carbs. It's got twin solex 44 PAI carbs.
 
I have been looking for that video for years!




It would take a LOT of work.
It would be cool to hear some input from that guy. There has to be others out there as well but they would most likely not be lurking on this forum but who knows. I feel like it wouldn't be incredibly hard to make happen, sure it would be much more difficult than adding bolt on parts to a civic or something. Everything would be custom like a twin blow through carb system and then you would have to find a good spot to mount a supercharger and also what supercharger to use.
 
Hello Dave
What size boat do you have ?

I have been working on a 18' SeaSport Sportsman for the last few years. It has a 125b in it.
I was an Automotive tech for over 20 years , picking up info for engine setups / props has been quite sketchy.
The boat sat for over 20 years, the water pump corroded right off the front of the engine, and of course Penta doesn't make that pump anymore.
I was able to purchase 2 250c running cores from a local dealer here in Anchorage.
My first though with everything that I was able to find out about the 125b is that it is massively under carbed
The engine has the A cam in it, I was going to bolt on the dual carb intake off one of the 250's but even so. the solex doesn't have a choke, and here in Alaska I didn't see it worth the time or effort to rebuild the carbs .
I added a redline Kit K861
http://www.carburetion.com/Products/ProductDetails.aspx?Part=K861
Then added an MSD Ignition 6560
https://www.msdperformance.com/products/ignitions/marine/marine_ignition/parts/6560
Just finished a round of test and tune on Big Lake here in Ak, running a Solas 15.3 x 19 cuped 3 blade we got 34.3 mph according to the Lowrance at about 4400 rpm
we also tried a Solas 14 x 21 4 blade cupped and got around 33 mph out of that at about 3750 rpm the trip before, but we had a detonation issue and set the timing back to 8 degs
out last trip we used octane booster but I didn't have time to swap the 3 blade for the 4 blade and play with the timing.

I think I might be able to get 4k with a timing adjustment out of the 4 blade, if so that would really be about the power band I would like to be in, the MSD is multi spark 3k and under, I'm thinking that would be the best for economy, what I can say though is we ran it last weekend for 4 hours on the lake and use 12 gallons of gas.

what pitch prop / speed / rpm are you running now?
 
Go to a V8 closed circuit cooling system if you want some easy power. Besides my 40 years of experience, knock yourself out. Even worse than on terra firma, the water world will consume gobs of horsepower and money.:omg::nod: And, this isn't really much of a boating forum, historically.
 
I get 35mph out of my 86 19.5 Bayliner with a aq125B 2.1L redblock all stock except the 15X19 stainless steel prop at about 4500rpm. Historically I can fill it up and roll up to the Oregon City Falls and back home to Scappoose Bay all out all day and still have 1/4 tank of gas. Try that in your V8...
 
I get 35mph out of my 86 19.5 Bayliner with a aq125B 2.1L redblock all stock except the 15X19 stainless steel prop at about 4500rpm. Historically I can fill it up and roll up to the Oregon City Falls and back home to Scappoose Bay all out all day and still have 1/4 tank of gas. Try that in your V8...

It seems like there would be no comparison, BUT gear ratio makes a difference. My boat is going 35mph at 3000rpm, using less fuel than the equivalent 4 cylinder (in the same boat) that's running wide open at 4500rpm. I'm sure you get better economy but the lower rpm cruise speed helps a lot with economy.

If I'm going full tilt 50mph @ 4500rpm, you can forget about fuel economy, but it's fairly easy on gas at 3000rpm.
 
Not much need for a v8 in this boat nor do I think trade off in the weight/fuel consumption would be worth it for more speed.

The little red block does a Great Job! I'm over 30mph which is where I wanted to be and I get 3 gallons per hour with it.

My next project is to overhaul the 250's with turbos and put them in a little twin v landing craft.

And Yes you are correct. this is not a boating forum but as I recall, Dave was asking about his boat motor which just so happens to be a OMG.... wait for it ....

A Volvo RED BLOCK
 
It's not a boating forum, but there's no reason B230s cant be B230s here..

OP if I were you and wanted a bit more power, I'd investigate tight squish head gaskets and maybe looking into different carb conversions (weber makes a nice kit, more reliable than the solex's) and the Swede guys make adapters for running DCOE type carbs.. would be a big gain. The V cam you have already is kinda ideal if you want to be on plane quickly and cruise at 4k rpm all day.. The K might be a little choked up in the low revs, and advancing it too much with an adjustable gear might kill whatever power gain you would have had if it were timed straight up. The cams were made to breathe a certain way at certain RPM.. If you want more grunt I'd look into sourcing an A cam and play with valve clearances, leave it timed straight up. If you want to experiment with a K, please do! But I wouldn't recommend advancing it too far or you might end up with less performance than the V straight up.. If all you want is insta-torque get a T.
 
Hello Dave
What size boat do you have ?

I have been working on a 18' SeaSport Sportsman for the last few years. It has a 125b in it.
I was an Automotive tech for over 20 years , picking up info for engine setups / props has been quite sketchy.
The boat sat for over 20 years, the water pump corroded right off the front of the engine, and of course Penta doesn't make that pump anymore.
I was able to purchase 2 250c running cores from a local dealer here in Anchorage.
My first though with everything that I was able to find out about the 125b is that it is massively under carbed
The engine has the A cam in it, I was going to bolt on the dual carb intake off one of the 250's but even so. the solex doesn't have a choke, and here in Alaska I didn't see it worth the time or effort to rebuild the carbs .
I added a redline Kit K861
http://www.carburetion.com/Products/ProductDetails.aspx?Part=K861
Then added an MSD Ignition 6560
https://www.msdperformance.com/products/ignitions/marine/marine_ignition/parts/6560
Just finished a round of test and tune on Big Lake here in Ak, running a Solas 15.3 x 19 cuped 3 blade we got 34.3 mph according to the Lowrance at about 4400 rpm
we also tried a Solas 14 x 21 4 blade cupped and got around 33 mph out of that at about 3750 rpm the trip before, but we had a detonation issue and set the timing back to 8 degs
out last trip we used octane booster but I didn't have time to swap the 3 blade for the 4 blade and play with the timing.

I think I might be able to get 4k with a timing adjustment out of the 4 blade, if so that would really be about the power band I would like to be in, the MSD is multi spark 3k and under, I'm thinking that would be the best for economy, what I can say though is we ran it last weekend for 4 hours on the lake and use 12 gallons of gas.

what pitch prop / speed / rpm are you running now?
Hi sorry it's took so long to reply. It's a 20 foot citation.
Currently I have a solas 14.75 x 15 3 blade prop. Max speed is 39 knots at 5000 rpm, will cruise at 30 knots at 4000 rpm.

Thanks David
 
Sounds good. Here is the drop in get rid of the points kit I used for my aq125b 2.1L redblock 19.5 Bayliner bow rider penta 270 outdrive boat. Does 34.4 miles per hour with stock single solex. 15x19 stainless 3 blade prop about 4500rpm.

http://www.ebay.com/itm/AccuSpark-E...ash=item4845adb422:g:8gYAAOSw9NdXrFfu&vxp=mtr

<iframe width="560" height="315" src="https://www.youtube.com/embed/O5Zcxz6KhZU" frameborder="0" allowfullscreen></iframe>
 
Last edited:
Sounds good. Here is the drop in get rid of the points kit I used for my aq125b 2.1L redblock 19.5 Bayliner bow rider penta 270 outdrive boat. Does 34.4 miles per hour with stock single solex. 15x19 stainless 3 blade prop about 4500rpm.

http://www.ebay.com/itm/AccuSpark-E...ash=item4845adb422:g:8gYAAOSw9NdXrFfu&vxp=mtr

<iframe width="560" height="315" src="https://www.youtube.com/embed/O5Zcxz6KhZU" frameborder="0" allowfullscreen></iframe>

That's the very same kit I fitted, what a difference. Starts 1st turn of the key and idles perfectly.
 
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