Ventilation 65hp chrysler

[jimmbo]

Maybe so. Ballistic is an off the shelf prop, no fancy custom tuning. So if I'm not slipping, I am loading the engine which pulls the rpms down so it's a crap shoot, less slip and less rpm hopefully for more speed. But that's a crap shoot till you do it.

I tried a Ballistic in 99 on my 150 Johnson. My experience with it was not good. It blew out on corners, had poorer acceleration than the stock aluminium prop, and showed not speed increase. I switched to a Raker. It held on like there was no tomorrow, and had better holeshot, even with an extra inch of pitch. I was able to raise the engine 3/4 in higher on the transom, and gained 4 - 5 mph over the stock AL prop and remained within 50 of the AL prop. Maybe it works well on your boat, my mileage differed

 

[las]

I have an old parts catalog where the specifications says 65 hp at 5250 rpm, I just thought I had seen 5500 rpm some where.

If we assume the pitch is 13 inches now and over the winter the bottom will be made smooth, that would raise the rpm even further I'm thinking! In that case I would have to go one or two steps up in pitch.

 

[Sea Rider]

Las,

If at 5500 wot revs and spec calls for 5250 as supposedly the max. + 250 rpm is nothing. Can compensate adding extra weight or throttle bit less, that's if liking running full hammer down. Much preffered than going one more in pitch. Will have better hole shot at slight less top end speed.

Happy Boating

 

[jimmbo]

65hp @5250, that's the rpm where it is rated 65hp. There is a recommended range of rpm that extends above and below. It is very likely 5000 - 5500 rpm. It could also be 4750 - 5750 rpm. Most, but not all engine makers, placed the rated rpm in the middle of an rpm range, with a tolerance of 250 or 500 rpm on either side. Again, Chrysler for many years, opted for a range of 500 on either side of the rated rpm, but... So, the Maximum RPM could be 5500 or 5750. It really does come in handy to have the spec. Is there a model/serial number plate on the engine? These often had the WOT RPM range on them

Edit:
Going thru my collection of old Engine Brochures, I never found one with a 65hp. But it did have a 2 cylinder 55 and a 3 cylinder 75 hp. Each had a different gearcase and thus different dia props. the 75 used a 13 x 17 in and the 55 showed a 10 x 13 as props shipped with these engines. gearing was 2:1 for the75 and 21:13 or 1.62. Even in Mercury Accessory Catologs I could not find a prop listing for a Chrysler/Force 65hp.

I will concede the prop is in the neighbourhood of 10 dia. and the gearing of 1.62 The speed and rpm obtained put you in the range of a 12 or 13 in pitch. Cleaning/truing up the hull should yield another 1 or 2, maybe 3 mph

 

[las]

I hear what you are saying, but wouldn't a cleaner hull up the rpm as well?

Jimmbo, the engine should be almost identical with the 55hp I think, from what I've learned, only the carburetors should be different.

 

[jimmbo]

I hear what you are saying, but wouldn't a cleaner hull up the rpm as well?

Jimmbo, the engine should be almost identical with the 55hp I think, from what I've learned, only the carburetors should be different.

A good hull will go faster, the percentage of slip will drop a tad, and yes the rpms will rise

I've never looked thru the parts lists for the 55, 60, or 65 but, the Carbs, porting, cylinder head, and exhaust could be different.