kens wrote:There is no real performance curve nor numbers for the little 3.0l mercruiser, it doesnt exist.
I have already researched that. It is not there, and, that little engine does not make 135hp. nor 140hp, nor 130hp.
it is reliable, and makes torque, it is a good engine, but the HP numbers don't exist.
that's because it doesnt make much HP. but, it will make torque.
I have the old version (non Vortec) and it makes about 112HP.
That is, if you assume for gasoline to provide about 10HP/per gallon/per hour. and that is generous.
My 3.0L engine burns 8.0 gallons per hour balls-to-the-walls.
That indicates to me 80HP.
At cruise, I burn 5.0 gallons per hour, and that tells me 50HP.
There is only so much BTU's of energy per gallon of gasoline, and as such, my little 3.0L engine is telling me that it is 112HP at the flywheel.
If you start doing the math with 112HP at the flywheel, then DEDUCT transmission losses, then DEDUCT strut bearing losses, and DEDUCT all the other losses, what you end up with is the numbers posted by my fuel flow measurements, AND that of Glen-L who designed it.
And at the end of the day, it is about 80HP AT THE PROP. hence my numbers of 8.0 gallons per hour, @ 10 HP per gallon per hour.
If you build your 27' True Grit, and install a 3.0L VORTEC engine, you may go up to 115HP @ flywheel, but not much beyond that.
It is a good engine, BUT, don't let the salesman sell you into 130HP. it doesn't exist.
It is a good engine, but only buy into 115HP.
It will make torque though.
Bill Edmundson wrote:Joe
If your engine will turn 4800, I assume it's not diesel. At 10 knots, that's about 65% of WOT. That is about right for gasoline. Diesels at 80-85%. The prop estimates should be good as starting point. Cruise RPM should bee about 2875.
thanks guys. I took way too long in my responses and ended up losing everything I typed up. Lots of calculations that I should have done on paper and transferred to the post instead of working it out as I type . I'll retype it all later.