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Old 05-13-2016, 04:36 PM   #1
Dave7575
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Default Volvo penta aq151

Hello I'm new and after some advise. I have a aq 151 and would like to change the cam to gain bhp. I understand it comes as standard with a v cam.
My question is which cam can I fit that would gain bhp without any other modifications ? And what would be involved in me changing it ? Or is there anything else I could to simpler ?

Thanks David
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Old 05-13-2016, 06:37 PM   #2
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Is your AQ151 in a boat or did you swap it into a car?

There are lots of opinions on what cam is best, but the "V" that you currently have is already a good one. The "K" cam will give you more upper rpm power.

Here's a cam change walkthrough:
http://forums.turbobricks.com/showpo...3&postcount=64

The Volvo Greenbook manuals are also a good resource:
http://www.k-jet.org/documents/green...ion+2+-+Engine

#protip use google to search the board. Type site:turbobricks.com and keywords in to the search engine.
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Old 05-14-2016, 03:29 AM   #3
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Originally Posted by oldschoolvolvo View Post
Is your AQ151 in a boat or did you swap it into a car?

There are lots of opinions on what cam is best, but the "V" that you currently have is already a good one. The "K" cam will give you more upper rpm power.

Here's a cam change walkthrough:
http://forums.turbobricks.com/showpo...3&postcount=64

The Volvo Greenbook manuals are also a good resource:
http://www.k-jet.org/documents/green...ion+2+-+Engine

#protip use google to search the board. Type site:turbobricks.com and keywords in to the search engine.
Thank you for your reply and info. The engine is still in my boat. I was looking for some low down power. Are k cam's readily available?

David
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Old 05-14-2016, 03:34 AM   #4
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The engine is still in my boat. I was looking for some low down power. Are k cam's readily available?

David

Have you tried different pitch propellers? That is what I would start with if I wanted to hotrod me boat.

"Low down" powah, eh? I suggest advance the ignition timing for lower end power. If you hear knock, time for higher octane fuel.
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Old 05-14-2016, 05:43 AM   #5
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Have you tried different pitch propellers? That is what I would start with if I wanted to hotrod me boat.

"Low down" powah, eh? I suggest advance the ignition timing for lower end power. If you hear knock, time for higher octane fuel.
Hi and thanks for your reply. Have changed my prop, it's a happy medium between time to plane and top speed. From memory the ignition timing is set a 6 °btdc. How far could I advance do you think ?

David
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Old 05-14-2016, 11:20 AM   #6
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Yeah Man!


I have been in a boat with a Volvo redblock. Any boat with a 4 banger is gonna be slow outta the hole. Unless it's a really small boat and you are driving it by yourself. Once you add passengers, don't expect much out of a redblock. You could always convert to V8 if you really wanted to get moving, but you already know that. I had a 4.3L Chevy V6 in my last powerboat and it was adequate, but V8 woulda been nicer. Heck, next boat is gonna have an outboard instead of a car engine rusting away and taking up space in the bilge.

Stock timing is 12 degrees +/- 2, I think. So crank it up above that and see what happens.


Another way to change the powerband is advance the cam with an adjustable cam gear. Any of the car engine B230 ones will work. Might be worth a shot.


I am still thinking playing with the prop is gonna yield the best response, but its been a while since I have owned a powerboat and played with different props.


I don't know what cam comes in there, but also playing around with different car cams would be fun too. With a boat, you spend most your time at high rpms, so I wouldn't really try to tune it too much for low end power with sacrifices at the top.
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Old 05-14-2016, 04:23 PM   #7
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Anyone plus t'ed a aq151 or 171(thats the 2.5 right?) in a boat?That would be fun
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Old 05-14-2016, 05:55 PM   #8
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Quote:
Originally Posted by Canadan View Post
Anyone plus t'ed a aq151 or 171(thats the 2.5 right?) in a boat?That would be fun
I think one of the issues is the availability of road-tax-free
high octane gas.

Marked gas is typically only 89 octane at best, and of dubious
quality sometimes at that.

Then there are the heat issues. Boat engine bays do not typically
get the same kind of airflow a car engine sees.

Boats often have carbs, the marine environment is harsh on
electrics.

That all said, I'm sure it has been done.
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Old 05-14-2016, 09:26 PM   #9
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I think one of the issues is the availability of road-tax-free
high octane gas.

Marked gas is typically only 89 octane at best, and of dubious
quality sometimes at that.

Then there are the heat issues. Boat engine bays do not typically
get the same kind of airflow a car engine sees.

Boats often have carbs, the marine environment is harsh on
electrics.

That all said, I'm sure it has been done.


I guess if you keep your boat on the lake, but im used to towing them add 93octane and convert to microsquirt, remove hood and profit? I dunno been around v8 hot boats all my life so i always dreamed of a turbo rotary or sr20det powered boat but b230/b250f+t sounds like fun..

That and the old addage "it takes 10hp to make 1mph in a boat" makes me think a cam swap or timing adjust isnt worth much in an underpowered boat.

Just speaking out my ass here, carry on
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Old 05-15-2016, 10:13 AM   #10
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They have turbos on diesel engines on boats, but they don't get nearly as hot as gas engines.

The hard part about turboing a gas boat engine would be re-engineering the water cooled exhaust. There are closed circuit cooling systems (heat exchanger and coolant) and there are raw water cooling systems where the water you are floating on is pulled up thru the outdrive, then goes into the water pump, thru the engine, thru passages in the water cooled exhaust, and then out the tailpipe and then thru the exhaust in the center of the propeller.


Volvo AQ 171 looks like it has a closed circuit cooling system= uses a heat exchanger=does NOT pump raw seawater thru cast iron. Damn my manifolds rusted out fast on my last boat with raw water cooling. If I ever do it again, going with closed circuit cooling system. Converting was $500+ so I didn't do it.

Volvo AQ151:



AQ171:






Last edited by ZVOLV; 05-15-2016 at 10:23 AM..
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Old 05-15-2016, 03:17 PM   #11
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Yeah Man!


I have been in a boat with a Volvo redblock. Any boat with a 4 banger is gonna be slow outta the hole. Unless it's a really small boat and you are driving it by yourself. Once you add passengers, don't expect much out of a redblock. You could always convert to V8 if you really wanted to get moving, but you already know that. I had a 4.3L Chevy V6 in my last powerboat and it was adequate, but V8 woulda been nicer. Heck, next boat is gonna have an outboard instead of a car engine rusting away and taking up space in the bilge.

Stock timing is 12 degrees +/- 2, I think. So crank it up above that and see what happens.


Another way to change the powerband is advance the cam with an adjustable cam gear. Any of the car engine B230 ones will work. Might be worth a shot.


I am still thinking playing with the prop is gonna yield the best response, but its been a while since I have owned a powerboat and played with different props.


I don't know what cam comes in there, but also playing around with different car cams would be fun too. With a boat, you spend most your time at high rpms, so I wouldn't really try to tune it too much for low end power with sacrifices at the top.

Thanks. So after reading everyone's thoughts if I'm going to stick with this engine my option is the adjustable cam gear and a k cam. Next issue is sourcing the cam and cam gear.

David
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Old 05-15-2016, 03:23 PM   #12
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I know of someone looking for this Aq151 for a boat..
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Old 05-15-2016, 03:38 PM   #13
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I know of someone looking for this Aq151 for a boat..
Okay here you go, thank me later.

https://seattle.craigslist.org/oly/boa/5585128700.html

Oh and FYI I know of another person in the area that is always looking for them also, not for boats, but to part out and make money selling the parts to volvo race car guys....

They cost quite a bit of money usually. This link is a 250 which is a later aq151c they just renamed them and it's rebuilt in a boat for 2k... Hard to beat that. Personally when my redblock boat blows, I will just put a car motor in it..
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Old 05-15-2016, 05:19 PM   #14
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Originally Posted by ZVOLV View Post
They have turbos on diesel engines on boats, but they don't get nearly as hot as gas engines.

The hard part about turboing a gas boat engine would be re-engineering the water cooled exhaust. There are closed circuit cooling systems (heat exchanger and coolant) and there are raw water cooling systems where the water you are floating on is pulled up thru the outdrive, then goes into the water pump, thru the engine, thru passages in the water cooled exhaust, and then out the tailpipe and then thru the exhaust in the center of the propeller.


Volvo AQ 171 looks like it has a closed circuit cooling system= uses a heat exchanger=does NOT pump raw seawater thru cast iron. Damn my manifolds rusted out fast on my last boat with raw water cooling. If I ever do it again, going with closed circuit cooling system. Converting was $500+ so I didn't do it.

Volvo AQ151:



AQ171:





Yeah i know, i was thinking remove the engine lid and just go with a dry exhaust like jet boats and inject water after the turbo. I guess if you wanted to get real fancy you could make a manifold and hot side of the turbo wet. Maybe i should just try it one day.
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Old 05-15-2016, 11:29 PM   #15
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T cam + adjustable gear?
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Old 05-16-2016, 10:32 AM   #16
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On a boat, the holeshot only really matters to me if trying to pull up a wakeboarder/skier. The fun is at WOT. I would be building for higher RPM pull! But that is just me. 4 bangers will struggle pulling out a skier but are much better on fuel. I wouldn't mind having a Volvo fishing boat! And then I would hotrod it to get TO the fishing spot as fast as possible!
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Old 05-16-2016, 07:04 PM   #17
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I have heard of people putting superchargers because of the exhaust manifold you can't use turbo.
https://m.youtube.com/watch?v=9m0HZXQqC1M
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Old 05-16-2016, 07:27 PM   #18
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I haven't found an extensive description of what it takes to add a supercharger on a redblock in a boat. I might would get a little concerned about running temperature and cooling. But then again here is a video of a boat running twin Saab 2.0T engines and I don't see a radiator but I bet it's on there somewhere.
https://m.youtube.com/watch?v=lINUW17kBk4
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Old 05-17-2016, 10:12 AM   #19
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I have heard of people putting superchargers because of the exhaust manifold you can't use turbo.
https://m.youtube.com/watch?v=9m0HZXQqC1M
Hi thanks. Watched the video. Supercharging sounds very interesting. Any more info on how's it done ?
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Old 05-18-2016, 03:41 AM   #20
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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?
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Old 05-18-2016, 07:09 AM   #21
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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.
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Old 05-18-2016, 09:47 AM   #22
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I have been looking for that video for years!


Quote:
Originally Posted by Dave7575 View Post
Supercharging sounds very interesting. Any more info on how's it done ?
It would take a LOT of work.
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Old 05-19-2016, 12:00 AM   #23
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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.
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Old 08-05-2016, 11:28 PM   #24
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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/...aspx?Part=K861
Then added an MSD Ignition 6560
https://www.msdperformance.com/produ...ion/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?
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Old 08-06-2016, 01:39 AM   #25
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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. And, this isn't really much of a boating forum, historically.
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