brains06
Member
- Jul 23, 2007
- 144
- Boat Info
- 78 Sundancer 260, Humminbird GPS 528i
- Engines
- 350 Mercruiser with Pre-Alpha outdrive
Ok everyone, I just posted this on another thread but I thought it needed some legs. We talk about this stuff all the time but no one ever just laid down a format to use so that we can post and compare all in one place. Maybe keep someone from putting a little kid prop on a big boy boat. So heres what I've found
Ok so we've heard 16 x 16; 15.25 x 15, and 16 x 14 are good for the carbed 350
I have experience with the first two and like them both...but I'm intriged by the 16 x 14. I'm not running quite right at the moment so after a tune up I may pull some numbers with both 16 x 16 and 15.25. I think what we need to do or consider doing is making a base line test thread for each engine. Over the last month or so I can say I've posted at least 15 times on this very subject. This is not a complaint though. With prop pitch and RPM's being the single biggest performance change/mod we can make nearly on the fly its really good that people are smart enough to ask before doing something stupid. So I'm gonna see what I can find out and maybe start a thread based on my findings with the 350. It would be great to see a sticky on the subject with each of the more popular engines. Also we havent really dug into some of the variables that come with finding these numbers along with fuel burn (another ridiculously hot topic), such as tab usage, boat weight, direction of travel vs. current and so on. For example...
1978 260 Sundancer single carbed 5.7 merc.
5100# dry
1/2 tank
tabs fully retracted or bow up
Traveling UPSTREAM/DOWNSTREAM with a 15.25 x 15 prop
3200 rpm - 17 mph/19
3600 rpm - 23.5/26
4000 rpm - 26/29
4400 rpm - 31/36
These numbers are also with my canvas down and just me. I've hit 36 though with my 300# buddy on board though. I'll have to check the numbers for the 16 x 16 but if I recall my midrange numbers were better but top end wasnt as good.....I probably need to switch it huh? I'll have to test it out and see. Either way, I'll get this thread started and lets see what we find.
Ok so we've heard 16 x 16; 15.25 x 15, and 16 x 14 are good for the carbed 350
I have experience with the first two and like them both...but I'm intriged by the 16 x 14. I'm not running quite right at the moment so after a tune up I may pull some numbers with both 16 x 16 and 15.25. I think what we need to do or consider doing is making a base line test thread for each engine. Over the last month or so I can say I've posted at least 15 times on this very subject. This is not a complaint though. With prop pitch and RPM's being the single biggest performance change/mod we can make nearly on the fly its really good that people are smart enough to ask before doing something stupid. So I'm gonna see what I can find out and maybe start a thread based on my findings with the 350. It would be great to see a sticky on the subject with each of the more popular engines. Also we havent really dug into some of the variables that come with finding these numbers along with fuel burn (another ridiculously hot topic), such as tab usage, boat weight, direction of travel vs. current and so on. For example...
1978 260 Sundancer single carbed 5.7 merc.
5100# dry
1/2 tank
tabs fully retracted or bow up
Traveling UPSTREAM/DOWNSTREAM with a 15.25 x 15 prop
3200 rpm - 17 mph/19
3600 rpm - 23.5/26
4000 rpm - 26/29
4400 rpm - 31/36
These numbers are also with my canvas down and just me. I've hit 36 though with my 300# buddy on board though. I'll have to check the numbers for the 16 x 16 but if I recall my midrange numbers were better but top end wasnt as good.....I probably need to switch it huh? I'll have to test it out and see. Either way, I'll get this thread started and lets see what we find.
