When I had the new motors installed last fall we installed the same 21 Rev 4's that I had been running on the old motors. They worked well but the max RPM was down from the mfg full throttle range a little (although the boat was 8 mph faster than with the old motors). This spring I got a set of 19 Rev 4's to bring up the max RPM. I was quite surprised (and disappointed) with the results, so last weekend I put the 21's back on. Speeds and mpg were back, but the river was too crowded to do a full throttle run so I only re-checked up to 5000 RPM.

Here are the comparison. Speeds are all GPS, but I didn't do two way runs so they can be off by +/- 1 mph based on the tide current speeds in my local river.

Economy cruise:
21" Rev 4000 RPM 38 mph 1.6 gph (from the Smartcraft)
19" Rev 4000 RPM 35 mph 1.4 gph

High Cruise:
21" Rev 5000 RPM 50 mph (didn't bother to look at mpg, but less than 1)
19" Rev 5000 RPM 45 mph

Max:
21" Rev 5800 RPM 58 mph
19" Rev 6000 RPM 51 mph

Boat: 32' Scorpion Racing (not a Chris Craft) Full fuel, about 8000 lbs
Motors: 250 Verado on 20" setback B-Bracket

-Greg

Greg,

Glad to hear that the boat is doing well with the new motors. What is redline on them?? I like to turn 5800 on my 225, but the Verado's may be more, I just picked up a 21 Revolution 4 labbed prop that I may try this weekend.

RIck

Rick,

I'm very happy with the new motors. They are quiet, smooth and reliable. Recommended RPM is 5800-6400, so I'm technically in the range but many people recommended getting toward the top of the range so I thought I'd try the lower pitch prop. Just surprised at the major loss of speed across the board.

How's your boat running?

-Greg

Motor is running great, but I am also a few hundred RPM, and a few MPH short of where I want to be, just dont have the cash to buy a bigger motor right now, so taking it easy on her.

Bigger pitch almost always run better cruise speeds. The WOT numbers are strange. I expected 300-400 diference with a much closer speed.