Crusader 5.7s gas guzzlers?

[Porchhound]

About to look at this 1988 Tolly Sport Sedan, but with gas climbing faster than a rocket launch I'm concerned with fuel costs keeping me tethered to the marina this summer. I've read the Crusaders are superior (build) than mercruisers. I'm happy with 7-8kts, what should I expect for a fuel burn?

Will running the 5.7s at 12-1500rpms cause engine issues?

 

[rslifkin]

What length is the boat? That'll help determine what speed will make for an efficient slow cruise. With small blocks, I'd figure you should be able to manage close to 2 nautical miles per gallon at a knot below hull speed. Depending on the weight of the boat, probably about 0.7 - 0.9 nmpg on plane.

As far as running continually at low RPM, there's not much to worry about. Most gassers tolerate it pretty well. If they're closed loop cooling, run 160 or 170* thermostats (nothing colder). And consider adding oil cooler thermostats to help get the oil temps up under light load. Keep the idle mixture on the carbs set as lean as you can still get a good idle (will help avoid carbon buildup at low rpm, keeps them from stinking when maneuvering in the marina and will save a hair of fuel at slow speeds with no effect at higher speeds). I've yet to do the oil cooler thermostats on my boat (with 454s), but I've run them at 1300 rpm for hours on end numerous times (including going probably 30 hours of runtime without exceeding 1500) and everything stays happy, spark plugs still look good, etc.

 

[Porchhound]

She's a 30ft. Tollycraft, probably 11,000lbs dry

 

[sunchaser]

The elephant in the room with 30-40 year old gassers is not the small difference in OPEX but safety. Old tanks, valves, lines, filter bodies, carbs etc are potential leak and drip points.

The penalty for overlooking these issues, no matter how seemingly minute, can prove disastrous. Fume detectors and one's nose should be on full alert when looking at old boats with gas systems. Monel tanks, new lines and modern fuel delivery systems are a great solution. Ive had several gassers but spent time on keeping odors and fuel system repairs under a careful eye.

 

[rslifkin]

She's a 30ft. Tollycraft, probably 11,000lbs dry

In that case, efficient slow cruise is probably down around 6 kts due to the short waterline. 7 - 8 will be plowing a good bit of water and burning more fuel. And at that weight, it'll probably be at the upper end of my estimate for nmpg on plane.

The elephant in the room with 30-40 year old gassers is not the small difference in OPEX but safety. Old tanks, valves, lines, filter bodies, carbs etc are potential leak and drip points.

The penalty for overlooking these issues, no matter how seemingly minute, can prove disastrous. Fume detectors and one's nose should be on full alert when looking at old boats with gas systems. Monel tanks, new lines and modern fuel delivery systems are a great solution. I had one set up like this, it was very nice and odor free.

Yes, I agree. Fume detector is a must have, any fuel lines of unknown age should be replaced, etc. Tank material doesn't matter too much in my mind as long as they're in good condition, mounted so they stay dry, etc.

 

[tiltrider1]

A gallon of gas makes less hp than a gallon of diesel. This is why diesel’s are more fuel efficient. Gas has other favorable properties but they are less desirable in boating. The other factor is torque. Diesel engines are designed for high torque low RPM were 5.7 gassers are designed to be lower torque and higher RPM. This adds to them being a little less fuel efficient. You put these two inefficiencies together and you probably burn 20% more gas than diesel. Now if 20% breaks your budget you probably can’t abord boating anyway.

 

[Porchhound]

What I can afford and what I'm willing to spend if gas prices get up near $7/gal (as some are predicting) are two different issues. If you don't believe me, see how many high dollar yachts leave the marina this summer. On the other hand, if a person is willing to go anyway, the anchorages in the San Juans might be a bit more tranquil!

 

[tiltrider1]

Even at $7 a gallon the efficiency difference between gas and diesel won’t be the difference between go and no go. If you won’t go with gas, you won’t go with diesel. Doubling the cost of fuel will only increase recreational boat expenditures by 10%.

This response might sound like an attack but it’s not meant to read that way. I am only pointing out that while ones fuel bill is an in the face expense it is actually a small part of the overall expense of owning a boat.

 

[Bill V]

In 2006 I bought 2 brand new Crusader 350/310hp engines in crates and had them installed. I now know they were not superior to Mercruiser engines and that there is no such thing as a Crusader engine factory while Mercruiser does in fact have factories that build many of their engines. My engines came down an assembly line in Mexico owned by GM. My boat hull is similar to a 30 Tolly and gets 1.25 mpg at 3000 RPM. 1.6 - 1.8 mpg at 12-1500 RPM or 7 mph. They lasted about 900 hours and after disassembly they were found to be nothing but a standard auto/truck engine with a marine cam. Nothing really to be impressive. My present engines are built to withstand RPM levels of 3600 for hours at length should I choose to run them there, something the Crusaders could not do.

 

[Porchhound]

Thanks, I didn't take it as an attack. On the front end of deciding on a boat, I'm trying to factor in as much info as possible, nmpg being one of them. As a good friend often says, buying a boat is always about compromise...somewhere.

 

[tiltrider1]

My crusader experience has always been with the 454 big block. This engine is no longer available through crusader. In the 80’s and 90’s Crusader took 454 truck blocks and marinized them. They used a very simple logical design that worked well and was low maintenance. Mercury always added complexity to their systems to gain 5 more HP. Over this time Crusader gained the better reputation because of its greater reliability. Now if you hang out with the fast boat boys you will find Mercruiser has the reputation for being the fastest.

 

[RT Firefly]

Greetings,
Mr. P. As already mentioned by Mr. t (post #8) fuel is but a small expense in the overall scheme of the boating experience. Also as mentioned, one has to be absolutely anal about gasoline leakage and associated fumes.
Sniffing the bilge and a quick overview of fuel delivery system will become second nature during your pre-trip inspection.
We have a gas boat up in Canada. Single engine Mercruiser with original (1979) galvanized fuel tanks. At the beginning of last season, well before launch, I detected a noticeable odor of gasoline. One of the tanks WAS leaking. I emptied the tank and shut off the fuel supply, aired out the engine space well and ran the season on one tank. I did a quick bilge sniff EVERY time before starting and had no odors. Foolish? Perhaps, but I felt safe enough to proceed in this manner.
Historically I ran the bilge blower before every start, as well.

 

[Solly]

28' Chris Craft with a single 350 (5.7) I figured 1 to 1.5 nautical mpg. Usually ran around 8-10 knots, under 2000 rpm. Can't remember exactly.

No boat gets good mpg. And if gas is climbing so will diesel.

As far as I know every 350 (5.7) starts life as a GM short block. The marine cams can be the same as a truck cam. Maximised for lower rpm, more torque.

 

[rslifkin]

My crusader experience has always been with the 454 big block. This engine is no longer available through crusader. In the 80’s and 90’s Crusader took 454 truck blocks and marinized them. They used a very simple logical design that worked well and was low maintenance. Mercury always added complexity to their systems to gain 5 more HP. Over this time Crusader gained the better reputation because of its greater reliability. Now if you hang out with the fast boat boys you will find Mercruiser has the reputation for being the fastest.

On the basic low output engines in the 80s, the Crusaders were usually a bit beefier mechanically (they tended to use 4 bolt main blocks even on the low output versions, Merc only used them on the higher output versions). They definitely had the better exhaust design as well. But in the 80s, Merc had the better ignition systems (they switched to electronic ignition earlier, and a better system than Crusader used early on IMO).

On both the low output 350s and 454s, Crusaders were actually rated a few HP higher than the Mercs in the 80s. For the 454, Merc rated them as either 330 or 340 hp depending on sterndrive vs inboard and the year (early years were all 330, later became 340 for the inboards). Crusader rated the same engine (almost identical except for the 4 bolt mains) as 350hp. The extra 10 hp wasn't really a difference though, just in the way they rated it. Merc had a wider WOT RPM spec, so they rated it 340 at 4000 RPM. Crusader's spec was tighter (4200-4400 instead of 4000-4400), so they rated it at 4200 RPM which gave 350 hp.

Merc offered higher output options that Crusader didn't though, and Crusader didn't do sterndrives. Those 2 factors got the go-fast guys hooked on Mercs.

 

[DavidM]

Look for a later model Crusader or Mercury with electronic fuel injection. EFI improves milage a bit and almost eliminates gasahol carburetor varnish build up.

A good EFI gasoline engine can be expected to make 12 hp per gallon of gas at optimum rpms, less at wot and much less at low rpms. Diesels make 16-20 hp per gallon by comparison.

David

 

[mvRusalka]

I've got a 26 Tolly with a single Mercruiser 357 Horizon, which is a Merc factory remanufactured Vortec-spec EFI 5.7 with the dry joint style exhaust.


I can't speak to the quality of a recent Crusader, but can note a few inherent issues I'm not a fan of on our Merc.


1. The factory belt driven raw water pump ate its bearings and failed within the first 100 hours. I replaced it with a Hardin Marine Gen 7 stainless pump and never looked back.


2. The above issue was likely caused by what I believe is a pully misalignment issue that encourages tensioning the belt on the tighter side to eliminate chirping. I've seen some reference to a mysterious Merc service bulleting floating around on that one.


3. The belt tensioner is manual and requires frequent adjustment to keep it in the sweet spot, I'd much prefer a spring tensioner that would account for belt stretch and wear.


4. The cheesy plastic body distributors strip out on the cap screws if you look at them wrong. Admittedly, this is a GM problem, not Merc, and there are aftermarket options here too.


5. Exhaust reversion due to cam overlap, I pulled and inspected the elbows after 200 hours expecting to just replace gaskets, but found they were totally caked up with baked on carbonized salt deposits. I'm now religiously flushing the raw water circuit with salt away after each trip in hopes that will neutralize it enough to get more life out of the exhaust components. I'm planning to pull them again at the end of this season to see if that makes any difference.



6. The big one - also within the first 100 hours a sizeable rear main seal leak developed. We hauled the boat, pulled the engine and when the mechanic pulled the pan off, he noticed the problem immediately. When Merc remanufactured the engine, they installed a repair sleeve on the crank at the rear main seal riding surface. When that sleeve was installed, it wasn't driven square, and was also driven too far. The manager at the yard had some lengthy discussions with a regional rep for Merc and the response was along the lines of "this isn't the first instance of this we've seen." The warranty process would have required us to crate the engine up and send it to Merc for eval and a decision on whether or not to replace. I would have lost the season. Instead I just had the mechanic remove the improperly installed crank repair sleeve and install a new one properly, replace the rear main seal, and button it back up. It's thankfully been fine since.


Crusaders almost certainly have their own list of foibles, but it may all come down to whether you get a Friday afternoon build, or something bolted together with a bit more care.

 

[jimfrens]

I have a 1972 Chris Craft 28 Sports Express, probably less weight than the Tolly, but it has twin 5.7 Crusader Captains Choice 330 hp installed new around 2010. It gets combined 1 nmpg at cruise (20 knots). I haven’t done a long cruise at slow speed but I would expect about 1.5 nmpg at 7-8 knots. My boat is a deep V hull, the Tolly hull may be more efficient when planing.

That said, I believe boat condition is much more of a factor when looking at older boats than what engines are in it. I’d be more concerned with knowing that the engines have been taken care of than anything else.

 

[Art]

In our great condition 1977 34' Tollycraft tri cabin [17K lb. dry weight / 21K fully loaded]

Have a pair of 1977 Mercruiser 350 cid, 255 hp engines with Rochester Quadrajet carburetors. Port total rebuild / starboard full top end rebuild a couple hundred hrs. ago. Both engines run sweet!

Fuel use [mid-level load (19K +/- lbs.) with very clean bottom]:

1. One engine running at 4.5 to 5 knots = nearly 3 nmpg
2. Both engines running at 6.5 to 7 knots [7.58 calced hull speed] = 2 +/- nmpg
3. On full plane doing 16 to 17 knots = 1 +/- nmpg
4. WOT doing 21 to 22 knots = OMG nmpg. I'd guess 1/2 nmpg?? Never hit WOT except a minute or five for tests and if needed to do a really quick position adjustment due to area conditions.

IMO - 350 cid gas engines are good choice for relatively small pleasurer cruisers. They can run at all rpm levels all day with no problem. I don't recommended to run them too fast all the time though, simply due to increased overall wear and tear.