02 sea ray sundeck 270 8.1 vs 7.4 vs 5.7

[Siboatguy]

Hi I'm new to this form. And never wrote a form before so sry if its bad. Im looking at a 2002 sea ray sundeck 270 with the 496ho 425hp. I know a lot as i worked on all my old boats. How fast is this boat/Cruising speed,rpm? How hard is it to work on? Debating on if its just 6mph slower in the top end then the 5.7 do that.

 

[randmhall]

Hi and welcome to the forum

I have a 240SD with the 300 hp 5.7 and Bravo 3. Runs 45 mph or so depending on load and conditions. It will pull me up on a Slalom ski just fine, and I weigh in at an above average 275 lbs.

I have a good friend with a 2007 (or so) 270 SD. His has the 8.1 engine. Top speed is about the same as we go up and down our lake, but his boat is much heavier. Skiing with only a 5.7 might be a problem. Tubing you would be just fine. Also, his big block burns a lot more gas than mine. Good luck finding your new boat. And keep asking questions here, there are lots of folks who will chime in to help you out.

 

[Kingsfr]

I don't have any of those engines you listed... but, I have a 270 SUNDECK with a 6.2 L 383 Stroker rated at 325 H.P. at the prop (the 6.2 is a replacement for the 7.4). So that you can make a comparision, my SD will do about 42 MPH at WOT. At it's most economical cruising speed (approx. 26 -27 MPH) I get about 2.1 MPG burning about 11 GPH.
I don't know the weight of the 8.1L engine, but I know it's heavier that a 6.2L. I thought the WOT speed difference would have been more than randmhall stated (46MPH vs. 42MPH).
P.S. I always wished I had the 8.1L

 

[tdgard]

I thought the WOT speed difference would have been more than randmhall stated (46MPH vs. 42MPH).
P.S. I always wished I had the 8.1L

It is more. I'll get to 52 on gps in mine. I do a short blast once in the spring and that's it. He is right about the fuel. A gallon goes away in under two minutes at that speed.

 

[Kingsfr]

It is more. I'll get to 52 on gps in mine. I do a short blast once in the spring and that's it. He is right about the fuel. A gallon goes away in under two minutes at that speed.

Thanks tdgard. I was guessing the top speed would be over 50 MPH.
Do you know what your most economical cruising speed is with the 8.1L? and what MPG and GPH you are getting at that RPM?

 

[tdgard]

I normally settle in around 3000-3200. 32-35 mph @ 12 gph so just under 3 mpg.

 

[Kingsfr]

I normally settle in around 3000-3200. 32-35 mph @ 12 gph so just under 3 mpg.

Damn...I knew I should have held out for a 496! Those numbers are much better than mine. You cruise at lower RPMs, at a faster speed, burning less fuel.