The good, the bad and the ugly on a Volvo 5.7 ?? - The Hull Truth

Mako211cc · 10-01-2008, 08:27 AM

One of the boats on my short list has RWC, twin Volvo 5.7 inboards. Let me read all the inside informaton from former or present owners.

Thanks guys

Capt. Dan · 10-01-2008, 08:28 AM

What boat, Inboard or I/O?

Mako211cc · 10-01-2008, 08:31 AM

inboard

TODDMANCHU · 10-01-2008, 08:37 AM

I had a 1987 raw water cooler 5.7 270hp Volvo. It seemingly had more balls than my present 300hp GM 350. Downside.......Parts. Certain parts are unique, hard to get and very expensive. Other than that it was a great engine.

yottyboy · 10-01-2008, 12:12 PM

What type of transmission? If they are vee drive, I'd say avoid them, but straight or down angle transmissions would be better. Also, if they are old-school carb with points distributor you might want to rethink the deal. The EFI engines with electronic ignition are much easier to live with. I'd also think about the RWC thing. You'll be replacing manifolds more frequently than if you upconvert to Fresh Water Cooling. If you are a DIY, elbow grease type, then I'd say these will not give any more hassle than anything else.

ziess21 · 10-01-2008, 12:16 PM

What year motors are the ones you are considering?

Quote:

TODDMANCHU - 10/1/2008 5:37 AM

I had a 1987 raw water cooler 5.7 270hp Volvo. It seemingly had more balls than my present 300hp GM 350. Downside.......Parts. Certain parts are unique, hard to get and very expensive. Other than that it was a great engine.

Parts back then may have been an issue but today Volvo parts are readily available. In fact, Volvo has a 72 hour guarantee that parts will be available or they are free. I'm not sure if this applies to older motors though.

billinstuart · 10-01-2008, 01:54 PM

Raw water SALT WATER cooled Chevies may last 10 years before they rust out. SBC's are great engines, but they weren't designed to be salt water cooled. They will rust out long before they wear out.

Mako211cc · 10-01-2008, 04:43 PM

I guess it comes off the short list

kerno · 10-01-2008, 09:45 PM

The Volvo 5.7 is a Chevy 350 re-labled. That means that replacing an engine is not an expensive proposition. Chevrolet makes several crate motors that with a freeze plug change will work just fine in a marine application. They cost about $1760 brand new in the box. I priced one today for a friend. When it comes in, I'll swap the freeze plugs for brass ones and drop the engine in. If they last 10 years, that's $176 per year per engine. That's really hard to beat. The GM spec sheet says "Not intended for marine use", but other than the need to change freeze plugs, I've never figured out why. The part number is 12499529 and you can buy 'em here:

http://www.citycratemotors.com/View-...hp?ProductID=1

Mako211cc · 10-02-2008, 02:32 AM

The engines are 1995, orginal equipment, and have about 700 hours on them. The manifolds, risers, exhaust hoses, thermostats, belts were just replaced.

When you say the engines will rust out, I am assuming you mean the manifolds, risers etc and not the block.

I will be the first to admit I know little to nothing about inboards. I have been an outboard guy all my life and I am looking to step into something larger that I can do some tuna fishing in.

I appreciate all the feedback, Thanks

baypro21 · 10-02-2008, 05:14 AM

Quote:

kerno - 10/2/2008 12:45 AM

The Volvo 5.7 is a Chevy 350 re-labled. That means that replacing an engine is not an expensive proposition. Chevrolet makes several crate motors that with a freeze plug change will work just fine in a marine application. They cost about $1760 brand new in the box. I priced one today for a friend. When it comes in, I'll swap the freeze plugs for brass ones and drop the engine in. If they last 10 years, that's $176 per year per engine. That's really hard to beat. The GM spec sheet says "Not intended for marine use", but other than the need to change freeze plugs, I've never figured out why. The part number is 12499529 and you can buy 'em here:

http://www.citycratemotors.com/View-...hp?ProductID=1

Kerno - you might want to do some research before spending $1800 on that motor. That price sparked my interest as well, I plan to repower sometime in the near future. The cam is very differant from a stock Mercruiser cam. That chevy crate motor's cam is spec'd at .450 intake and .460 exhaust with 222 deg duration. My Mercruiser manual lists all small block V-8's (except for 350 magnum) at .263 intake and .269 exhaust but does not list duration. I suspect marine cams are low lift with longer duration. It's $400 more but michiganmotorz.com has a comparable vortec 5.7 that has a marine cam and already has brass plugs. It's rated at 295hp to 330hp depending on fuel system and exhaust. I've decided on the silver series, it's a little more money, $3800, but comes with everything except exhaust manifolds (mine are 1 year old). I don't trust my old cast iron intake and old carb so I'll feel better with all new.

billinstuart · 10-02-2008, 05:36 AM

No, I was specifically referring to the ENGINE..block, heads, and intake manifold. 13 year old salt water cooled Chevies are borderline, in my opinion. All too often rusted out intake manifolds are reinstalled on a new engine. Kern is correct as usual..virtually any 350 chevy engine will work fine.

My suggestion if you like the boat..go ahead and put fresh engines (NEW blocks) in the boat. Convert it to FRESH water cooling. The FWC engines run hotter, which will further prolong the life of the engines, and improve fuel economy.

A stock automotive cam will work fine. All the "marine" cam does is move the torque peak up a few hundred rpms. Since horsepower is simply torquexrpm/5252, the torque, thus horsepower, at CRUISE rpms will be virtually identical. Wide open, you may lose a few hp, but no one runs a basic inboard engine at anything near wide open for very long. Additionally, it will idle smoother (less overlap) and reduce the tendency to suck water into the cylinders.

CB Haws · 10-02-2008, 06:06 AM

Freeze plugs are one thing; but you forgot about the headgaskets. Someone already mentioned the cam. Volvo's are poorly designed. Even the older fresh water cooled engines only ran anti-freeze through the manifolds and not the block. Really stupid.

baypro21 · 10-02-2008, 11:58 AM

Yep, forgot about the gaskets, auto gaskets will rust out in short order. For the $400 differance I would stick to a dedicated marine engine and not have to disassemble my new engine to convert it, that, I'm sure would void any warranty. I was under the impression a marine cam was differant for a specific reason. Can someone explain the relationship of HP and torque of an identical engine that has a high lift/short duration cam Vs. a lower lift/long duration? I thought a marine cam gave the engine more low end torque over it's automotive counterpart. Torque will be at the top end anyway because of lots of RPM's.

Cracker · 10-02-2008, 12:50 PM

I know back 20 years ago when I helped my father replace a Ford 351 engine in one of his boats the firing order was reversed for the marine engine compared to the automotive one...

billinstuart · 10-02-2008, 02:56 PM

The marine cam has more duration and lower lobe center spacing..this translates to more overlap, which hurts idle and low end power. The marine cam is, in fact, more of a "performance " cam than an automotive cam. Lift may or may not be beneficial performance wise. In any case the more lift, the greater the wear on the valvetrain. Torque is not at the top end..it usually peaks at mid-rpm or stays flat for a while. Torque is measured. Horsepower is calculated. At maximum rpm's the torque is often way less than at lower speeds, but the rpms make the horsepower calculation higher.

Horsepower is simply the formula above..no magic to it.

76GMC1500 · 10-02-2008, 03:05 PM

Marine cams run a wider lobe seperation angle to reduce valve overlap and reduce the chances of reversion into the cylinders. However, in the 260 hp GM 350's, they don't grind a different marine cam. The only difference is in fact the freeze plugs and maybe the head gaskets.