Engines: 947 vs 951

[SabrToothSqrl]

Why... the hell does this engine have TWO names / Sizes?

SEA-DOO says it's 947, on ALL the specs. even the sticker on the ski says 947.

why do we insist on 2 names / sizes?

is there any logic / reason?

thanks.

 

[Jonnyivy]

I'm no expert,... but I thought the 947 was the carb model and the 951 was the injected model,................. but I could be wrong !!!

 

[RFoster130]

Same thing. They are actually all 951.2 CC if you want to be really technical. Its just one of those things where people call them different things. Same thing happens with the 787. Some call it a 787, some an 800 and some a 781. In all reality it is 781.6 CC.

 

[jhjesse]

The engine, whether carb or DI is a 947 type with 951.2 cc's

 

[Dennis]

Actually, either term is correct. The sticker on a 1999 GTX will say:
ENGINE TYPE: 947
ENGINE DISPLACEMENT: 951.2

 

[jhjesse]

Actually, either term is correct. The sticker on a 1999 GTX will say:
ENGINE TYPE: 947
ENGINE DISPLACEMENT: 951.2

Wow! I thought that was what I previously said. Oh well!! LOL

 

[Dennis]

Looks like we were both typing at the same time. Sorry about that. :cheers:

 

[crisso]

This is what I have.Wow .I now understand.UMMMMMMMMMMMMM. It goes good and hard:cheers:

 

[Dr Honda]

Also... on the "720" engine. It's actually a 717cc.

It's a thing... every manufacture does this. Especially the motorcycle guys.

 

[SabrToothSqrl]

AHGK?! why though?! does calling a 951 a 947 change insurance risk? EPA issues? WHY does this happen?

I can see a 648 or 649 being a '650' engine, but 947 and 951 are both non-round, not easy to remember... why not call it a 963 or 847.6969 or 951.987654321?!

 

[djredman99]

My best guess when trying to speculate how it gets refered to by two numbers...

When Rotax starts the project, they identify it with the "target" number, in this case the 947. From this point on, it is refered to as the 947 engine. Through design phases, the actual cc's of the engine change until they come to the finished product...951 cc's. To them it is still the 947 engine. If you ever noticed, in all the official shop manuals, the engine is always refered to as the 947.

The general public on the other hand, often likes to identify engines by their size (cc's) and in this case it is 951. Well this works well in the case of the 947, the 787 engine on the other hand is 781.6 cc's yet is often called the 800. So, this is where my logic breaks down. Could be that some group of slighty "stupid" individuals thought that rounding to 800 was the way to go and it stuck.

Anyway, this is all just a guess but it is how I try to rationalize it.

For reference:

717 engine = 718.2 cc's
787 engine = 781.6 cc's
947 engine = 951.2 cc's

 

[470]

Also... on the "720" engine. It's actually a 717cc.

It's a thing... every manufacture does this. Especially the motorcycle guys.

We use to always give the Kawasaki guys crap because they were notorious for having more cc's then the name plate while most others were below on their bikes.