8.1L Merc vs. 8.1L HO Merc

[Sindbad]

We just sold our 340 DA which had 8.1L. Now looking for 390 DA and coming across a few, but not sure if the 8.1L is adequate power. If anyone knows of a prior thread on this topic, just direct me, or would appreciate your thoughts and input.

Thanks.

 

[Jimmy Buoy]

From what I've read, the HO has more HP, but in typical 3500RPM cruising it produces less torque and actually uses more fuel. If the application boat is lighter it may not need the bigger torque and may also be geared to cruise at a higher RPM. The HO does have a higher WOT range.

That being said, the 390's I've seen all have 8.1's and seem to be powered properly. It's not just the engine but the transmission gearing, prop size, and efficiency of the hull design that makes it all work together.

 

[Sindbad]

Jimmy Buoy - thanks for the information.....your comments are consistent with other research I have seen. thanks again.

 

[Gary Hill]

Some first hand experience here. I had a 2005 390 for four years which is now owned by CSR member Escapade. That boat had the 8.1L Merc's. Now I have a 2008 40 DA which is the same boat but it has 8.1 HO engines in it. Both boats had the same tranny's.

There is a difference. It is not that great but you can tell. Top end speed is 1-2 mph more. Cruising speed is 1-2 mph more at the same rpm. Hole shot is slightly better. Per the smart craft the cruising mpg floats around .05 to .1 less mpg. Both boats float around .6 to .7 mpg per the smart craft when cruising.

If I had to pick between a couple of boats with these two power plants and everything else on the two boats being equal, I would definitely pick the HO boat. If I could not find a boat with the HO's I would not worry about it, but I would want one.

 

[Bottom Line]

Gary...just curious why you went from a 2005 to a 2008. We're the engines a major factor?

 

[Gary Hill]

Gary...just curious why you went from a 2005 to a 2008. We're the engines a major factor?

Engines were not a factor. I have signed a non disclosure agreement with SeaRay and can't talk about these things on any social media.

 

[Georgia SeaDawg]

That's never good to hear about a NDA.

 

[Gary Hill]

That's never good to hear about a NDA.

Sometimnes you just gotta do what you just gotta do!