What's the real difference between...

[croSSed]

... a late '80's model Merc. 2L V-6 150 and a Merc. 135 made off of the same block? How did Mercury account for the extra 15 hp?

TG

 

[JB]

Re: What's the real difference between...

That question comes up about all families of engines that share a basic block made by all manufacturers, croSSed.

There are about a dozen things they can change to change peak HP. They aren't telling which.

 

[Plainsman]

Re: What's the real difference between...

Maybe it was the HP at the engine and the HP at the prop?

 

[Frank Acampora]

Re: What's the real difference between...

Look at the RPM at which the horsepower is rated. A slightly different gear ratio in the lower unit could let the engine rev up a little more and generate the extra hp. Changing the port timing could also account for it. And that's only two ways to get it.

 

[Texasmark]

Re: What's the real difference between...

Sometimes the rpm's will be rated 250 lower; have seen that. But for Merc/Mariner, at least in the mid-late '90's, 135 and 150 were both rated 5000 to 5600 and the engines were both 122 cu in per the spec sheets in their sales brochures. Guess they used different carbs (choking the fuel/air off) and/or some different porting.

Seems like it doesn't make sense to have the same engine and strangle it but when you have a boat BIA rated for 135 max, you can't very well put a 150 on it and get your insurance agent or the game warden to buy into it. d

Mark

 

[WillyBWright]

Re: What's the real difference between...

Carb throat size and jetting, reed stops, exhaust tuning, timing variations. Two to all of the above. I think porting is the same on those two.