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Author Topic:   rpm and speed performance
johnnywhaler posted 08-04-2002 12:57 AM ET (US)   Profile for johnnywhaler   Send Email to johnnywhaler  
Here we go...I have an 83 Montauk with a 93 Johnson 100 HP V4 engine. With trim all the way down at WOT I am only getting 4000 rpms, speed is roughly 37 mph, If I adjust the trim I'm getting 49 mph at top rpm of 5300. Thats with just me and a half tank (14 gallons) of gas. With two other people aboard(an extra 300 pounds)top speed drops by 10mph. Does any of this sound abnormal?
Clark Roberts posted 08-04-2002 07:33 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Johnny, doesn't sound abnormal to me! However, if you drop prop pitch 2" you most likely will be able to turn 5500-5700rpm at WOT trimmed, light load (this would be ideal as engine is rated at 5500rpm max... I think!). Now, speed should be same or go up a little, hole shot will be better and you won't loose 10mph with addition of 300lbs. You should loose only about 2-5mph... Happy Whalin'... Clark... Spruce Creek Navy
johnnywhaler posted 08-04-2002 10:15 AM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Thanks C.R,..By the way what is prop pitch and how does one adjust it? Also, does anyone know where I can get a manual for 93 Johnson?
Clark Roberts posted 08-04-2002 12:47 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Most props can be re-pitched up to 2" up or down ONE time... if you have a good stainless prop it would be worth a re-pitch by good prop shop... if no stainless prop then investment in one would be worthwhile!
whalersman posted 08-04-2002 12:50 PM ET (US)     Profile for whalersman  Send Email to whalersman     

There is plenty of information on Props in the Continuouswave Reference section here:

For the Manual (Operators, Repair, or Parts?) for your 93 Johnson, try your OMC dealer or look on eBay. eBay has plenty of manuals from time to time, you just have to keep watching. I purchased a Parts Catalog and a Repair Manual from eBay for my 1985 70 H.P. Evinrude.


whalersman posted 08-04-2002 12:52 PM ET (US)     Profile for whalersman  Send Email to whalersman     
I know I typed the url in right. It just didn't go through. Try this one.

Salmon Tub posted 08-05-2002 04:50 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
As they say, Location!, Location!, Location! of the trim that is. I did a speed check just the other day, and with a second passenger, and 160 lbs. of Water (bait tank) only topped out at 4000 rpm. Trimmed all the way in. As I started to trim out, the RPM's started to climb, but the conditions where a little too rough to trim out, so could not get conclusive results. Had a headwind too, and all the load was in the stern. Will try it again in a few days with just me and no bait (hopefully no wind either).
Bigshot posted 08-06-2002 11:24 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
No matter what you drive, it will perform like crap trimmed in. You HAVE to trim out until the stearing gets light, etc. Your engine is maxed at 5500 so I think you are perfect in your setup. Learn to "tweak" the trim and it will perform excellent.

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