Unidentified wire

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,831
No issue with oil pressure. Oil gets hot and pressure drops, is no issue over cold motor. Your well above any issues where hot oil would be a problem
 

Scott06

Vice Admiral
Joined
Apr 20, 2014
Messages
5,717
Yeah i knew that a 21p 4 blade was equivalent to a 3 blade 23 and idk how the 4 blade did on the original boat it was on with this same engine i never really went full throttle because i was watching my rpm and i didn't over rev because I made sure to keep my eyes on the shop tach because testing was the main reason I was out there. I was just throwed back because for that prop to be the same as a 23p it shocked me at the speed lose between the 2. I'm just not sure weather to try a 21 or a 23 3 blade next ..

Also what did you think of the oil pressures ?
Your oil pressure is fine as a rule of thumb 10 psi per 1000 rpm is perfect so at idle 25 is great

You didn’t mention what is wot rpm for both props . You said at 3/4” throttle

What are both props running at wot
 

markhodges78

Chief Petty Officer
Joined
Aug 4, 2016
Messages
416
Your oil pressure is fine as a rule of thumb 10 psi per 1000 rpm is perfect so at idle 25 is great
Just wanted to make sure
You didn’t mention what is wot rpm for both props . You said at 3/4” throttle

What are both props running at wot
The 21p 4 blade I was running 4600 rpm at 3/4 throttle so I didn't go wide open and the 19 pitch 3 blade I was running 4400 @ half throttle so again I didn't really test at full throttle.. it's my understanding that max rpm is 4400-4800 is that correct?

The 21p 4 blade jumped up nice but it just wasn't hitting on much in the way of speeds so I jerked it off and put the 19p 3 blade on and got better speeds I think
 
Last edited:

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,831
Your WOT should be real close if not on 4800 rpm
4400-4800 is good and closer to 48 is better
 

Scott06

Vice Admiral
Joined
Apr 20, 2014
Messages
5,717
Just wanted to make sure

The 21p 4 blade I was running 4600 rpm at 3/4 throttle so I didn't go wide open and the 19 pitch 3 blade I was running 4400 @ half throttle so again I didn't really test at full throttle.. it's my understanding that max rpm is 4400-4800 is that correct?

The 21p 4 blade jumped up nice but it just wasn't hitting on much in the way of speeds so I jerked it off and put the 19p 3 blade on and got better speeds I think
If you havent hit wot with either you dont know what they are capable of .
This is the classic tradeoff on how you want to use your boat. If top speed is more important to you use the 3 blade. If you want better holeshot especiallyif loaded with people 4 blade is probably better

as mentioned U want to hit 4800 or so at wot this will prop the boat to be throttle responsive in all rpm ranges …there is a rev limiter so you wont over do it
 

markhodges78

Chief Petty Officer
Joined
Aug 4, 2016
Messages
416
If you havent hit wot with either you dont know what they are capable of .
This is the classic tradeoff on how you want to use your boat. If top speed is more important to you use the 3 blade. If you want better holeshot especiallyif loaded with people 4 blade is probably better

as mentioned U want to hit 4800 or so at wot this will prop the boat to be throttle responsive in all rpm ranges …there is a rev limiter so you wont over do it
Yeah I realized on my last run that my in dash tach was off by 400 rpm at 4800 rpm so when the dash says 4800 the shop tach reads 4400
 
Top