90hp verses 115hp

[dreamchaser]

had a 1981 90hp evirude changed to a 1983 115hp evirude ,everything being equal including the same prop i gained 4mph would this right ? thks .......was expecting a little more......

 

[DJ]

Re: 90hp verses 115hp

HP is HP. 25 more explains the MPH difference.

You might even get more if you prop the 115 correctly. That is to run at 5500 RPM-minimum (average-light load) at WOT (wide open throttle)

 

[dreamchaser]

Re: 90hp verses 115hp

5500 is no problem for this combination more like 56 57 hundred with a aluminum 21 pitch now ,,,,

 

[Dhadley]

Re: 90hp verses 115hp

If the 90 was set up exactly like the 115 (same height and prop) and you gained that much, you did great. Unless the 90 wan't running right. If the 90 turned the same prop the same 56-5700 it should have been pretty close to the same speed since both motors have the same gear ratio.

 

[dreamchaser]

Re: 90hp verses 115hp

yes the 115 was set up same height and prop .rpm was not as much on the 90hp somewhee between 53 and 55 about 300 less if i remember right ,wondering now how if a 140 is the way to go to get more speed

 

[Dhadley]

Re: 90hp verses 115hp

A 140 looper? Absolutely!!

 

[dreamchaser]

Re: 90hp verses 115hp

thks DHADLEY ,,,,was readin some of ur other responses in the prop forum ,tryin to get the tech terms around my brain in regards to props ie.rake pitch and gear ratio diameter as well . do u think a raker prop would make a difference as they like to "ride high"? bangin head against the wall........how bout liftin motor higher on transom .any ideas much appreciated, thku leo......

 

[Dhadley]

Re: 90hp verses 115hp

Yes, you're right -- a prop like a Raker or a Stiletto will like a higher motor setting (X dimension). That should definately give you more overall efficiency.

What kind of a boat is it?

 

[dreamchaser]

Re: 90hp verses 115hp

thks again DHADLEY, your a world of knowledge to me ...wished there was some of ur kind round my area ..the highperformance and tech sides of boating seems so bland here .x demension ??? never heard that term ....my boat is called a "terminator" according to the manufactuers serinal number which i found out was built in friday harbour in washington state ...people say it looks like a "ponga" boat very popular in mexico the rude dealer here has a raker im gonna try after raising the motor .maybe this weekend. thks .leo

 

[Rancherlee]

Re: 90hp verses 115hp

Your 83' 115hp is equivalent to a 86+ 90hp engine. I tore down a 81' 115hp for the block to rebuild my 88' 88spl and both engines had the same Timing, 1 3/8" carb size, porting, and exhaust plates. The only thing the 115hp had different is filler plates behind the read cages which I really don't know how much power those are worth. You could get a set of 1 5/16 carbs and the "humpback" exhaust off a 86+ 110 crossflow to pick up another 20hp (the 86+ 110 makes the same power as an older 140hp does)

 

[dreamchaser]

Re: 90hp verses 115hp

sounds good to me rancherlee ,,,, jetting all the same as well? going to try and see if i can locate the parts. thks

 

[dreamchaser]

Re: 90hp verses 115hp

was is the max rpm on a 1983 115 ,,,,changed prop lowering pitch form 21 to 19 tach showed 6600 needless to say i didnt hold it there for long or is my tach out of wack

 

[Tacklewasher]

Re: 90hp verses 115hp

Rated is 4500 to 5500.

Most hear seem to say max it at 6000.

6600 sounds high. It could get there if propped wrong, but I wouldn't do it.

 

[dreamchaser]

Re: 90hp verses 115hp

certainly not going to run at 6600 ..... wouldnt last long