97 175 Johnson on a 19' Champion Best RPMs

[ollison]

I am trying to prop for speed. I have 1997 Johnson 175 non fuel injected out board on a 19' champion boat. What is the best max RPM power range for top end and what is the best top end prop today. Several years ago I was always impressed with RAKER Props. What pitch do you guses?
Thanks

 

[rndn]

Re: 97 175 Johnson on a 19' Champion Best RPMs

The rpm's at wot should be between 4500 and 5500 trying to get near the top end of the range for peak efficiency.
Before someone can provide a good estimate for a prop it would help to know the following:
What prop are you currently using, ie: aluminum, SS, and Michigan Wheel., Raker.
What diameter and pitch are you using?
What is your top speed at wide open throttle (WOT)?
What is the max rpm's you achieve with your current setup?

 

[Dhadley]

Re: 97 175 Johnson on a 19' Champion Best RPMs

The 60* loopers love rpm, don't be afraid of it. With mine I shoot for 6000 minimum. That's a decent boat and the Raker will give you an advantage with bow lift. The Turbo Lightning is a good choice too. To take advantage of either prop you'll need a jackplate, 6" setback minimum. Depending on load and which model you may gain some with 2" spacers.

What props have you tried and where are you at with them?

 

[ollison]

Re: 97 175 Johnson on a 19' Champion Best RPMs

Someone said over 6000 is blow up level. I have a Hydrolic jack plate but can not figure best use of it. Do you adjust up the faster you go. How low should a prop shaft be past the bottom of the boat to start.. I had a cream puff 4 blade that was alittle smaller than my gear housing 24 pitch and it ran Solid 59 and almost 60 on GPS at 5800. I trying a rougher 24 3 blade raker that is even with housing and gained about 1 to 1.5 miles an hour about 60.9 at 5700 RPMs. My gas is descending so it may be just that on lesser weight. The boat seems to be torqing to the right. The trim fin may be dragging quite abit. I though about taking it off. I am really a fishing want abee and truely a race boat driver. Maybe I am ask to much out of my 92 champion. I just thought 65 ought to be possible with a 175. Thanks for your interest and reply.
Signed Fishing want abee, Race boat driver for Sure

 

[Gary H NC]

Re: 97 175 Johnson on a 19' Champion Best RPMs

Man! Scale the text size down! Geeze!!

 

[Dhadley]

Re: 97 175 Johnson on a 19' Champion Best RPMs

All that shouting gave me a headache.......

Anyway, ask whoever the "expert" was on rpm that if 6000 is "blow-up range", how come the rev limiter is at 6700 on some? And what does he mean by "blow-up"? Will the valves float and bend a pushrod? Will the springs break and cause a valve to hit the piston? Rocker arms won't take the rpm?

Oh wait -- this is a 2 stroke. It doesn't have any of that un-necessary junk.

Back to reality - the jackplate height will depend a lot on the technology of the propeller. Most likely you'll start with it down and pull it up as you get going. You may indeed find that the faster you go you have to drop it a tad. If you run a prop with a lot of lift, the faster you go, the more boat is out of the water.

On my flats boat I can take off with the plate all the way up. That's to get on plane quickly in very shallow water. Yes, it blows out some but once up I can drop it some. But I have a prop that most folks have never seen. A Turbo Lightning will do almost the same thing.