Crusader 220's VS. 270's

C

ChefJunk

Member
exMember
Joined
Oct 30, 2007
RO Number
28882
Messages
454
Sorry for so many 3007 AC questions!

On a Carver 1981 3007 Aft Cabin, what would the positive and negative points of having twin 270's over the 220's?

I am assuming the 220's would be a Chevy 305 - 5.0l and the 270's would be chevy 350 - 5.7 litre? Please correct me if I am wrong.

Would my fuel economy suffer with the 270's? By how much? Assuming of course equaly loaded and maintained vessels.

How much "faster" would the 270's propel the boat over the 220's?

The hours for the 270's are 1010 (star) and 1030 (port).

ALSO, would the shafts counter rotate? Or do they both rotate in the same direction?

Anything else to add in would be great. I appreciate everyones opinions and experience as I am trying to learn as much about this boat over the winter as possible.

Thanks,

Jim
 
Fuel usage will increase, 270's are Chevy 350CID's. Not sure about the diff between the 220 and 270 speed wise, that's pretty much dependent on the boat. I have th 84' 350's and burn about 22-25 an hour at about 3100 rpms and cruise at about 18Mph. I have the Carver 3207 aft. The shafts are counter rotating btw.......
 
Hmmm, I wonder what is better these days. After all, the larger displacement will result in poorer fuel economy. On the other hand, there are engines out there based on the 5.0L block (same as the 220s) which now pull a lot more HP than 220. What about fuel injection? You could get 260HP and more that way. I'm not a mechanic but I've heard of people doing it. Or take your engines, rebuild them and bore oversize, and get a modest horsepower gain that way without sacrificing a ton of efficiency. Perhaps our buddy Ram will take a crack at this one...
 
I'm only guessing...yes, the 5.7 will burn more than the 5.0 at the same RPM level. However, you should be able to run the 5.7's at a lower RPM and achieve the same speed the 5.0 would give at higher RPM's.
Let's say for sake of argument that the 5.7 will run 20 knots at 3200 RPM and the 5.0 will run 17 knots at 3200 RPM. Now, slow those 5.7's down to 17 knots and I'm guessing fuel mileage will be no worse (maybe even slightly better) than the 5.0's.
 
Jim...the shafts do counter rotate, but the engines do also. The stbd engine is right hand rotation, and the port rotates left.
 
I agree that the fuel consumption would be close if running at same mph. I would want those 270's with the hrs near 1 thousand, it would give me some piece of mind that they would have more life left than the 220's.

ja
 
I don't think it's the hours on the engines that count as much as the condition of the exhaust system. Before I purchased my 3007, a thorough survey revealed problems with the risors and so forth. The seller agreed to a complete repair or the same money toward an upgraded replacement. We opted for the replacement, investing $1500, which I believe will buy at least another thousand hours for my 220 hp Crusaders. Currently, they have 1200 hours on them.

-Greg
 
Are there any published service standards for maintaining such "high-mileage" marine engines??? For example, do you switch to 20W-50 oil at some point, or Amsoil, or Dr. Goop's Mystery Gel (fictitious) or something else??? What about other Preventative Maintenance items on an engine that old, like the timing gears and such???
 
Like the idea on "published service standards for aged engines" but have yet to see any.

ja
 
I've read a lot of data in magazines and on forums that mileage doesn't improve by running a lower rpm. You do run less fuel per hour, but, on the flip side, you don't travel as far in the time period. 3400-3600 seems to show the best actual economy.
 
You must log in or register to reply here.
Back
Top