Yamato 102 hp/torque

[glen wesanko]

I'm running a 102 on a hydro in CSH,20SSH,OSY-400. I'm somewhat new and was wondering what rpm I should be aiming for on the straight. This engine will spool up to 7200 easily . The information from the Yamato manual shows peak torque @ 5500 rpm and peak hp @6600 rpm . I only have 4 props so I'm trying to figure out which way to beat on them!

[johnsonm50]

I'm running a 102 on a hydro in CSH,20SSH,OSY-400. I'm somewhat new and was wondering what rpm I should be aiming for on the straight. This engine will spool up to 7200 easily . The information from the Yamato manual shows peak torque @ 5500 rpm and peak hp @6600 rpm . I only have 4 props so I'm trying to figure out which way to beat on them!

I dont have the answers but want to add to the Q.. The torque/hp specs given are for the motor raced in Japan, once here and gone thru professionally [whatever is done to make it run and still be legal] would those specs be raised a bit? Plus if its turning more Rs than the specs -that still translates to more speed, [if your not falling back coming out of turns], is that a bad thing?

[sam]

I don't recall anything that is legally done that would dramatically increase torque on a 102. The biggest thing we do with them compared to when they are at home in Japan is run them higher on the transom, which dramatically increases speed, but has no effect on power.

Its OK to run a little beyond the max hp of a motor, that is how you get good punch. The 99 44/100 if the time we are on the race course we are either below or above the max output of the motor; the key would be to average pretty close to the power peak for the whole course including the turns.


You'd only try to set up a boat to exactly match max hp rpm on a kilo boat.

I think the answer to Glen's question is that it varies with the length of the course and driving style. There may be a "best average" top rpm, but I bet not all winners run the exact same peak rpm.