Volvo Penta 350

"Hi,

I'm looking at buy

"Hi,

I'm looking at buying a boat with a Volvo Penta in it, but the guy that is selling it has said something that bothers me. so I want to see if you guys can answer a couple of questions for me?
He said that he just put a brand new block in the boat, But it is a performance truck block that he got and just put all the old volvo penta stuff on it. He said the head and all the other components are off the old motor and it was a 260hp setup, But he said with the new block it is a 290hp setup now. There are only 22 hours on the new setup and I'm told it runs great (we are going to do a sea trial this week). A friend of mine told me today that with the truck block in there that it will all hold togather for about 100 hours or so but then I will have problems with the motor again. is this true? Has anyone else used a none marine block before?

The guys selling the boat told me that the motors are almost the same when they come from GM, the only differents is that Volvo Penta takes the block changes a couple of LITTLE things and jacks the price up 3 times as much.

I plan to use the boat alot during the summers to run off shore and get the yellowfin & yellowtail so I need something that is going to run good for me. Also what kind of MPG can I expect to see with this setup? the boat is a 28 footer with a duo prop.

Thanks alot for the help!!!"

"RE: " hold together for a

"RE: " hold together for about 100 hours..."
I have no idea where he got that number from...maybe wiser heads than mine ???

Re: "changes as couple LITTLE things.....3 times as much"
That's just the beer or other recreational intake talking. Among the "little" things, BY LAW: flame arrestor, distributor, alternator, starter, exhaust manifolds, exhaust elbows and fuel pump. Then, there is the raw water pump as well a several feet of special hose and numerous stainless steel clamps and often a fuel filter with spinoff replaceable element w/water seperator.

Is the engine raw water cooled or does it have a heat exchanger?

Re: "a 290 HP setup". I doubt it although its possible. Too many variables. "Performance Truck block ???" Marine engines have special cams. Its not just about HP, its about the torque curve. Also... the HP you get also depends on the carb and its calibration. (I assume this is a carbed engine).

RE your "MPG". Too many variables, i.e., hull type (deep V (and how deep) vs modified V)... cuddy cabin vs center console vs flybridge...etc. Boat weight. As a "SWAG",
I'd say between 1 and 2 mpg. With a 260 HP on a 28 ft, it won't be a speed demon. I have a 350 CID 260 HP on a 4000lb 23 ft Deep V cuddy cabin and we are talking a 30-32 mph cruise with 40 as top end."

"This is a difficult question

"This is a difficult question to answer without more details and without knowing what the guy used in the rebuild. A 350 GM does have many possible configurations and different cabs/cams/heads/WOT RPM will give different HP. There are also several types of blocks (pre 1985, pre-Vortec, Vortec). This will give you and idea

http://www.ebasicpower.com/faq/gmsmallblock.htm

Basically, that engine may just run fine for many years or it may not, depending on what they have done to it. To my knowledge there is no difference between the "marine" and the "truck" GM block. If your engine is raw water cooled and they have used marine head gaskets in the rebuild I do not see a problem in principle. If the engine has a closed cooled system ("fresh water/antifreeze"), automotive gaskets will not be a problem anyway.

Never heard of a marinized truck GM engine having problems after 100 running hours, unless they used the wrong gaskets/components.

MPG varies with type of hull, engine setup (carburated or fuel injected, size of carb, etc), speed and "driving habits". With your setup, I would expect at least 16 gallons per hour with the boat doing around 25 knots."

"The boat is a 28ft 1988 Troph

"The boat is a 28ft 1988 Trophy with a 10ft beam deep 'V' and it has a cabin as well. The system is a closed cooled system (fresh water). The guy selling the boat said that the only thing he changed was the block, all the other parts are marine grade. Also yes it is carburated, I was told the boat has a top speed of 40 mph.
Like I said I just want to make sure that it has the range that I need. I run 40-75 miles off shore sometimes and I want to make sure with a 150 Gal/Tank I will be able to do that?
So do you guys thing it would be a safe setup?

Thanks a lot guys!
"

"I can elaborate more on this

"I can elaborate more on this later, but the truck block will no doubt be using a fully dished piston, a piston that should by all rights be considered a low compression smog piston never intended for marine use! IMO.

Much will depend on the size of the hull and type of hull. Small boat...... eh, you may be OK.

The SBC Marine engine fights Detonation.
A quench style piston/cylinder head combination is a far better choice if this engine is to be installed in a cruiser size hull.

Before you tell me that this is commonly found in the M/C engines, I fully agree. You will also notice what they do to their TAT in these engines. Look at the specs for TA.

Will it work and hold up? Well, again, the size/style of hull will be a determining factor.

Fully agree with the head gasket issue. If raw water cooled, they will eventually fail, and when they do, more damage than just gaskets will occur."

"RE: range... using the old 1/

"RE: range... using the old 1/3 out, 1/3 back and 1/3 reserve...
40 mile trip... 120 miles of fuel needed. You should be OK with a 150 gal tank.

75 mile trip...225 miles of fuel needed, At "Els" estimate, which is fair. You are looking at 123 gal required for that same trip (assuming statute miles) with reserves.

Then again... will you be chunking with the fleet, or trolling?

However, if EL's estimate is off..? If range is going to be an issue for you, invest in a fuel management meter. There are some relatively inexpensive ones out there.

RE: "THE SEA TRIAL". You very much want to find out what the MAX WOT RPM is. You don't need to run the engine for more than a 10 seconds at that level...(Some folks don't like to do WOT) You just need to know what that number is.
Current 350 CID 260 HP have a WOT range of 4000 to 4400 or 4600, depending on model. If you can't get 4000 RPM with a normal load ( couple folks on board, full tanks) there may be a problem.

BTW... some Volvo Owner's Manual indicate that running at 500 RPM below MAX WOT RPM is safe.
I have heartburn with this number. If you run at that RPM, i.e. WOT-500 you are asking for reduced engine life. I've spoken to marine engine manufacturer engineers (not marine engine marinizers) and they indicate that 75 to 80% of MAX WOT RPM for cruise will result in good engine life. Running at 90%.... not so much.
At WOT, engine life is measured in 10s of hours, BTW. I suspect that running at Volvo's recommended max will just insure that the engine will last thru the warranty period. FWC marine engines that are run in the 75 to 80% WOT range can expect thousands of hours of life.... That's block, etc. Manifolds and elbows only have several years of life."

"We took the boat out yesterda

"We took the boat out yesterday! There were 4 of use on the boat and the boat had less then a 1/4 of tank of gas. it started right up and sounded pretty good, as soon as we got past the point he opened her up to full power and left it there. It ran at 3800-4000 RPM! I had never seen anyone run a boat at full power so I asked him wy he ran it at full power like that, he said that the boat was under proped. He told me you are supposed to get 4500 or so RPM'S out of this setup but becouse it was under proped that is wy he is only getting 3800-4000 RPM. He said on his hand held GPS that it said that at 3900 RPM the boat was doing 36 mph but it did not feel that fast to me it felt more 24 mph. But I could be wrong.
We ran about 4 miles or so out and back at full power the hole time almost, and the boat did not go past 160 on the temp gauge so I was happy with that.
So please guys tell me what you think about the boat. I really dont want to buy a problem, but I do like the set up of the boat and the the deck space it has.

Thanks,"

"Your seller is a little misin

"Your seller is a little misinformed on the issue of the truck engine.
And he is misinformed on the prop issue.
If anything, the boat is OVER-PROPPED!
Engine damage can occur when over-propped and when the correct WOT RPM cannot be reached!
When you prop down, you will loose top speed, but you won't be over-burdening the engine!
Now you need to see if the numbers still suit you.

But let's move forward here;


28ft 1988 Trophy with a 10ft beam deep 'V' eh?
Is this a Bayliner Trophy? This would typically be an OMC drive in a 1988 Bayliner boat!
If so, RUN! Find another boat to consider!

However, you do say that this is Volvo Penta and with the Duo Prop drive!
Maybe this is a converted drive system! If so, learn what type of conversion, and which drive they chose.
[an OMC Cobra to DP-S conversion vs an AQ series Duo Prop "complete" installation.... (a better choice, imo)]

Not a huge issue, but the rpm at which some of these engines are rated at are not within an rpm range that we operate our cruisers or fishing boats in (such as this Trophy boat).
Example: One of the 5.7L Vortec engines is rated at 315 HP, but at 5,100 or 5,200 RPM........
5,100 is an RPM range that we just don't operate at...... Period!!!!!!
The owner's suggested rating of 290 HP for this truck engine is probably unrealistic in two respects, and if it were, it too would be at an RPM range that we just don't operate at.
260 HP is more realistic and is plenty of power, IMO.... especially with the DP.

Also, things change for me when I see the truck engine being used in much above a 24 footer.
The problem is not necessarily the build of the block, but rather the possibilities, or likelihood, of detonation with this configuration.
(there is NO quench area with this piston/head configuration in the SBC Marine engine)

Detonation, as I've said earlier, is one of the SBC Marine engine's worst enemies!!!!!!!!
To a degree, Detonation can be controlled by several factors:
**Higher octane rated fuel.
**Cutting back TAT (total advance timing)
The latter hurts performance.

I'm not all warm and fuzzy about the camshaft either, but you can do a few things to aid in avoiding water in-gestation.
Keep a good exhaust back-flow prevention flapper on the drive.
Keep your idle rpm on the high side, etc. yet allowing for an easy, smooth shift.

His top speed of 40 mph is likely a WOT speed, and not a cruising speed.
The Duo Prop lower unit is a "God Save" for this engine, IMO.
It will created a little less engine load, while maintaining, and even increasing, performance for this hull, IMO. This is Good!

I think that your range question may have more to do with the fuel capacity and drive than this engine......... the Duo Prop will greatly increase your range, possibly being closer to the range that you say that you wish to have.
I don't know for sure, as I have not owned this hull before.
Roberts suggestion of "1/3 out, 1/3 back and 1/3 reserve" is dead on!


Definitely ask the owner to remove and clean the prop shafts so that you can verify this.
The Duo Props must come off approximately twice annually for cleaning and re-greasing of the splines.... particularly in salt water!
They are among some of the more "Corrosion" prone propeller/shaft combinations.
If he can't get the props off, then they must be cut off.
I know what I am talking about on this one. I've cut some beautiful propellers from these drives in the past for this very reason!
So make this part of your criteria if you go forward with the purchase.

Also, very important.... while you have the propellers off, remove the ring anode and verify the final drive ratio by reading the numbers that will be stamped into the bearing carrier (AQ series drive, that is)
If the over-all ratio is correct for this SBC engine, it will be 1.95:1.
No other ratio will work correctly for this engine and hull!
(a surveyor will know about this)


I see that you did go for a sea trial.... and with the hull loaded as you would intend to use the boat. This is good!

Have a survey performed, both mechanical and structural.
Once in a while, a seller will burden a portion of the survey cost, and then maintain a copy of the survey should you not purchase.
It's worth the asking!


One final note! To me, an engine replacement is among the easiest and less headache type issues to have on this size boat so long as the purchase price is in line.

Post back so we can learn what you decided.
Good luck!
Be safe!"

"RE: "Engine Replacement&#

"RE: "Engine Replacement". My philosophy about boats and engines...(FWIW!)

Buy a GOOD top of the line (quality not necessarily price) hull that suites your needs...For instance for me, that is a 20 something Deep V cuddy cabin. Great for me and mine, maybe the worst thing on the planet for others. If it's an I/O, look for a 200 series Volvo. I've owned Mercs, will never do so again...and forget about OMC.

Engines... Given that a good high quality hull will last a loooong time (mine was built in 1969!) and the obscene prices on new (often not as well built as older boats)... I ALWAYS go with a brand new factory engine at re-engine time. If you look at the labor to swap parts and the risk...I don't see the economics of doing a block replacement. Unless its a relatively new engine that met an untimely demise.

If you look at the cost of ownership and aggravation factor over the time one owns a given boat, you can't find the cost difference between a block replacement and a brand new engine.

When I bought my current boat, I looked at the purchase price as the HULL price, fully planning on putting a brand new engine in it and changing the drive from a 250 to a 280... and keeping the boat a looong time.

If I was looking at a operational profile that included long off shore runs, I'd want a bulletproof setup...(at least here on the East Coast where things can and do get nasty fairly quickly "out there")

Further "Rick E's" comments about being overpropped. Yep it is. Since I doubt the owner changed the props (if he did, ask for the old ones), my suspicion is that the "new" engine, far from producing the claimed 290 HP isn't even producing 260. AND... running an overpropped engine at WOT because its not getting to spec'd RPMS is just plain wrong headed. Re-read my post on operating RPMs.

If you are serious about buying this particular boat, get an independant mechanic to run a compression check. Habitual operation @ WOT on an overpropped engine is a recipe for burned exhaust valves.

Who we are on this forum... "Rick E." and "El"
are both professional marine mechanics who know Volvos like the back of their hand...
Me... A loooong time boat owner with an engineering degree and a USCG Masters License who has almost always done his own maintenance and repair work and worked on many friend's boats. I'm not in "Els" or "Rick E." league when it comes to detailed knowledge of Volvos. It's just that in almost 50 years of boat ownership (mostly Volvos) I seen and fixed a few things.

I'm not saying that this boat is a bad deal, but it does warrant a closer look...i.e., get a survey like Rick said. Make sure the surveyor you get (you may need two seperate ones) KNOWS Volvos. Ask for references. I had my sailboat surveyed (Yes, I am masochistic enough to own two boats!) and I watched while the surveyor missed some things that I had already found."

"Here is where I'm at guys

"Here is where I'm at guys, I love the size and layout of the boat and it being an all fiberglass hull makes me like it even more. But let me give you the whole story so you guys can give me the best advice you can.

The guy said the boat was pulled from its slip this time last summer and was dry docked while they changed out the motor. When they did the motor they did the seals on the outdrive and put new stainless props on! Along with new bottom paint, cables and hoses and all that good stuff. but since the boat has been back in the water for almost a year now, I'm a little worried about what kind of condition the out drive and bottom are in.
The boat ran great yesterday but like the rest of you I was blown away to see he runs the boat at full power and that it is only at 3800-4000 RPM. He said they made one long trip in the boat this year were they left on Thursday and went out to Catalina island and fished during the day and pulled in to the cove to sleep at night and came home on Sunday. He said they did the hole trip on one tank of gas and the covered about 140-160 miles the hole trip. When they got back the boat was pretty close to empty on gas.

Now these are the things I'm looking at. I like to fish 4-5 guys on my boat and this boat can do it no problem. My wife wants something roomy and comfortable for her and my son when they go and this boat is that as well. But I don’t want a slip!!! So I would have to find a trailer for the boat, which I think I have for $3500. The boat does not have the electronics it needs to be a good off shore fishing boat so I would have to do that as well which is another $4000 or so. The guy is asking $11000 for the boat so I was going to try to pick it up for $9000 or so but I don’t know what his position is on that yet. The other thing I was thinking about was my truck towing it but I think I’m safe with my 2500 Chevy pulling it. The boat is 5500lbs - 6500lbs I think!
I’m trying to keep the price around 20k for a boat, and the only other boats I have been able to find is a 26 foot striper, and you are limited on deck space with those. But with all the info I'm getting back on the motor and what did he switch and what did he not switch out is got me worried to.

What do you guys think? Like I said I love the size of the boat and the room I would have. But I'm very worried about the motor and how reliable it would be? Along with how long would it last?"

"RE: "my 2500 Chevy pullin

"RE: "my 2500 Chevy pulling it. The boat is 5500lbs - 6500lbs"

Plus the weight of the trailer itself...

AS far a fuel consumption... within the expected range, but high. If the engine isn't propped correctly and you run WOT, mileage will suck."

"I just got off the phone with

"I just got off the phone with the manufacturer and they said yes the boat is over proped if it is running like that. He said spec calls for a 15 1/2 by 13 prop! and the boats top speed would be around 35mph and cruise at 25 or so.he said it should run about 13-15 gallons per hour at cruise. The boat is 6000 LBS dry. so with gear,fuel and everything I'm going to need a trailer rated for 8500 Lbs or more."

"Something is a little bit fis

"Something is a little bit fishy here. The details and price would have been nice from the beginning!
Are you reading any of our suggestions? (yes, a little sarcasm in that! No offense!)

Also, props for the DP's are not spoken of in terms of 15-1/2 X 13 and so on!
In a Duo Prop sets, you will see Prop ID #s more like B-4, B-5 or C-4, C-5..... or F-4, F-5 etc. depending on which drive this is and depending on the SS or aluminum prop sets.

So, we're either not getting the straight skinny, or you are being given incorrect info from this party.

I'd still like to know which drive this is! And it would benefit you as well!

Survey, survey and survey!
This will be money well worth spending, IMO.


Post back!

."

"When "marinizing" a t

"When "marinizing" a truck block you can have problems by using the wrong pistons as Ricardo already mentioned (detonation and lower compression, which means less power), but also by not installing the correct cam for the application. If your engine has the wrong pistons and/or cam, it won't develop the power of the original.

Maybe you should consider asking the seller what did he actually install on the truck engine. Those details are quite important."

"Here's my take on the dis

"Here's my take on the dished pistons regardless of which SBC heads he may have used.
The dished pistons will make this more prone to detonation. In order to combate detonation, you must hold way back on the TA.
When we do this............, Camshaft being correct or not.... we don't get the power from the engine.
All of this matters because of the wedge shaped portion of the SBC head.

Again, the dished pistons in the SBC should never be used in a marine application!

Is this a deal breaker? I don't know!
The boat needs to reach WOT and it needs to perform for you.... that's the bottom line!

."

"Re: "3900 RPM the boat wa

"Re: "3900 RPM the boat was doing 36 mph"...

I just reread this... At 3900 RPM my 4000# 23 ft x 8ft beam Lancer cuddy cabin with two on board and a half tank does 40 MPH per the GPS..

I doubt that you can go from 23 to 28 ft, from 8 ft to 10 ft beam and from 4000# (dry) to 6000# dry and only loose 4 mph with the SAME engine.
(actually I have a circa 2005, 260HP MERC 5.7L) I don't care HOW good a Duoprop setup is.

I don't know where you did the sea trial, but 36 MPH is really "booking along"...especially in a 28 ft boat."

"I'm sorry for the dead ho

"I'm sorry for the dead horse redundancy here......, but this is an area that I find rather important for anyone building a SBC marine engine.


Just an FYI here re; the truck type dished pistons.

It is not necessarily the lower compression created with the dished pistons that is an issue..... we actually want a lower C/R .............. we don't want high compression ratios anyway for this type of engine.
The dished piston along with the smaller combustion chamber heads can give a C/R that is inline with what we need/want for a marine application.

However, this piston will NOT give us a quench effect (Q/E) in the area of/against the wedge portion of the SBC head. That is where the problem is!

It is this lack of the "Quench Area" or Q/E that makes this so un-desirable, IMO.
**A low compression quench piston w/ the small heads would have been a better choice.
**Even flat tops with the 76cc heads would have been a better choice.
**The 64cc Vortec heads work well on the 5.7L with a low compression Q/E piston.

Some of you know that GM uses this dished piston in some marine engines........ why GM uses this piston for marine use is beyond me and the likes of others as well!
Dennis Moore gives an excellent explaination of why this is so important in his "Small Block Chevy Marine Performance" book.

Back to the truck engine:
The dished area of this piston (when at/near TDC) gives the gasses a place to hide from the flame front, so to speak. (This would be the remaining area of the dish that comes up under the wedge area.)

The gasses in this area are not forced into the flame front where a more full burn can occur!
This often results in detonation......., of which is not good since we operate these engines in an RPM range (3,200/3,400/3,600 rpm) where detonation is much more prone to occur......... and on top of that, we maintain this RPM for lengths of time.
This will result in engine damage if not controlled.
How do we control it? By holding back TA and we then end up with less performance than what this engine is capable of!"