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  45 MPH with a 135 on my 17' Outrage / but too much RPM

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Author Topic:   45 MPH with a 135 on my 17' Outrage / but too much RPM
CHenry posted 10-01-2001 03:22 PM ET (US)   Profile for CHenry   Send Email to CHenry  
Finally got my new (to me) 1997 17' Outrage in the water over the weekend. We hit 45 MPH on GPS with a 22 pitch 3 Bladed Laser II prop. Air temp was 115 and the water was 82! I have a 1997 Mercury 135 (carb)

Only problem was that according to the tach we were turning nearly 6100 RPM! That's about 400 too much...If the tach is to be believed, I guess I'll need a higher pitched prop...I'm off to my local prop shop (Hill propeller) to get some info

lhg posted 10-01-2001 03:27 PM ET (US)     Profile for lhg    
Check the pitch on that prop. If your engine is a V-6 Merc, the Laser II props would only be in odd number pitches. The even number pitched performance props from Merc are for the mid size 4 1/4 gearcase, up to 125Hp engines.
CHenry posted 10-01-2001 04:24 PM ET (US)     Profile for CHenry  Send Email to CHenry     
Good info..thank you

Spoke with the prop shop and it is indeed a 21"...I knew that but fat fingered my post...thanks for catching my mistake.

Gave Hill (the prop shop) all the pertinent info and they have concluded (as I suspected) that my tat is off.

After they did a few calculations my RPM and speed didn't jive. I know the pitch is right (that's obvious), I know the speed was correct (GPS and mechanical) so the only other variable left is the tat.

Besides..thinking through this a little more...if I was at that high of an RPM wouldn't I set off an "over-rev" alert?!

The prop is a 4816546A4521P it is a 13 7/8 (3 Blade) with a 21" pitch (with square ventilation holes near the hub). I really like it...great hole-shot and absolutely no cavitation/ventilation even while turning sharply.

Again…I am very pleased with 45mph out of this boat

Chris

lhg posted 10-01-2001 05:17 PM ET (US)     Profile for lhg    
I also had occasion to drive the later 17 Outrage with a Merc 135 on it. It was very fast and your speed sounds about right. For years Mercury built their 150HP engines on this same 2.0 liter block. There isn't a 130-140HP range engine made by anyone that will keep up with it, 2 or 4 stroke. The 135 Optimax is also the best, and cleanest, of the current DFI's.
dgp posted 10-01-2001 05:17 PM ET (US)     Profile for dgp  Send Email to dgp     
Chris, with a 115 degree F ambient temperature your horsepower is down about 10%. HP ratings are calculated at 77 degree F.
JBCornwell posted 10-01-2001 07:43 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Howdy, CHenry. I have a couple of questions and a comment.

When did the maximum safe horsepower rating for a Montauk get raised 35%?

Since it hasn't been raised, what are you going to do about insurance?

A good 100, for which the Montauk is rated, will show you 45 smph when properly propped and trimmed.

Have fun, but get insurance before you hit anything or even let someone hit you. (Overpowered boats are defacto causes of any accident and their operators liable in most states.)

Red sky at night. . .
JB :)

Peter posted 10-01-2001 07:53 PM ET (US)     Profile for Peter  Send Email to Peter     
JBC

Note its a 1997 17' Outrage, not a Montauk. Its a very different animal!

Ed Stone posted 10-01-2001 09:10 PM ET (US)     Profile for Ed Stone  Send Email to Ed Stone     
That year 17 Outrage was rated 150 hp Max.
90hp min.My 17 had 115 johnson and was a
little under powered with 3 or four adults.
Ed Stone
JBCornwell posted 10-01-2001 10:06 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
OOOOOPS!!! My most humble apologies, gentlemen. Maybe it's these new glasses, maybe I just wasn't paying enough attention.

Red sky at night. . .
JB :)

Clark Roberts posted 10-02-2001 08:36 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Chris, the merc 135 rev limiter is set at 6200 rpm (I think!) and the main purpose is to protect engine if prop come out of water (no load overreving).. To rev to 6-8K rpm is normal in racing versions of these engines and only main differences are probably plastic/fiber reeds and hand balancing in the racing version. The V6 cranks are extremely rugged and since you didn't hit rev limiter all should be ok.. of course if it's the tach that's another story! Clark... The Old Man and the Sea

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