QuestionSir, I recently blew the B&S engine on my Toro zero turn mower (engine model 311777). I want to get a replacement and if possible, get a bigger HP unit while I can. 1- any negative to seeking a higher HP engine? 2- I've found a 21HP B&S engine, model 331877, but want to make sure it is good for a direct replacement. I've compared its IPL to the 311777 IPL and the main parts (sump, head, crank, cam, valves, rod, piston) are different but the other parts (starter, magneto, fuel pump, alternator, regulator, wiring harness) are the same. Any thing to worry about? 3- I'm thinking that as long as the crank size and block bolt pattern are the same, it should be an OK swap. Am I being ignorant in my thinking? 4- If I can get the current engine repaired, how much cost is too much such that I should just go ahead and purchase a new engine? Any cost less than that of a new engine or is there some % rule for such decisions?
I know it says ask A question and I've asked 4- forgive me but I want to take full advantage of your expertise. Thanks, David
AnswerA good rule of thumb on repair cost is, if the cost of repair exceeds 1/2 of the cost of replacing the mower, replace the mower.
The engine you want to purchase has a larger block, more displacement. You may have a problem alining the mounting holes and the charging system may be different.
It is always best to go with a direct replacement. The unit was designed to use that engine. If you want to go to more HP get an engine that uses the same block, crankshaft and charging system. Many times OEM's will use the same block for an entire series of engine models.
Hope this helps.
