Does anyone know the development story of the 998?

[stgdz]

Does anyone know how this engine and when it was developed at big blue?

My guess is it was right around 2014 when they agreed with Cat, but what were some of the decision points by the team to go with a turbo? I still remember watching the launch videos but they didn't go into much detail on the development of it.

 

[WarriorDan]

Does anyone know how this engine and when it was developed at big blue?

My guess is it was right around 2014 when they agreed with Cat, but what were some of the decision points by the team to go with a turbo? I still remember watching the launch videos but they didn't go into much detail on the development of it.

Not all you asked for but interesting background. https://www.snowtechmagazine.com/genesis998turbo/

 

[bjowett]

Here is the Yamaha tech paper on the sidewinder. I have not dropped it into the translator yet, so unsure how much info is there. https://global.yamaha-motor.com/jp/design_technology/technical/publish/pdf/browse/52ss04.pdf

 

[earthling]

A lot of the literature claims that the 998t genesis is a clean sheet design, but only clean in the sense that it was designed up front for multiple applications. The case for example is shared with the yxz with very minor differences. The pistons in the sled are unique due to the turbo. There is more info scattered about on the YXZ and airplane forums where the 998t gets repurposed for those markets and users are forced to dig into the motors in order to understand how to modify them for those specific applications.

 

[stgdz]

found this one on bush planes

 

[number1kyster]

I still can’t believe this engine hasn’t found its way into a production side by side. Perhaps the law team at Yamaha doesn’t like the risk vs. reward.

 

[Turboflash]

What? Yamaha YXZ1000R! Non-turbo 998. Same engine - different pistons, different head, higher compression, non-turbo, naturally aspirated. Other than that, it's exact same engine.

 

[fatchance]

I can't believe they haven't put the 1.8 liter and now the new 1.9 liter into a side by side. It's a longer block but it's narrow. Imagine what Hurricane and TD could do with this in a snowmobile!

 

[stgdz]

sxs measure displacement via cylinder and stroke + and forced induction. It's one of the main reasons that class 2's are limited to under 1000cc and they have oddball CC's with turbo's.

If it goes over then it gets into the sandrail designation.

 

[number1kyster]

What? Yamaha YXZ1000R! Non-turbo 998. Same engine - different pistons, different head, higher compression, non-turbo, naturally aspirated. Other than that, it's exact same engine.

I meant the 998T. Polaris and Can-am are selling rigs with over 200HP. Yamaha could have dropped this in the YXZ years ago. Rumors were floating around that Textron wanted it for the Wildcat XX and Yamaha wouldn’t let them use it.

 

[sideshowBob]

Reflecting on Yamaha's development and application of the 998T does not leave a warm and fuzzy feeling as all of this has come to an end. Yamaha's snowmobile legacy...done. Use of Yamaha engines in sleds also done since Artic Cat has been mothballed.
Hopefully the New Year will bring better news.

 

[earthling]

I meant the 998T. Polaris and Can-am are selling rigs with over 200HP. Yamaha could have dropped this in the YXZ years ago. Rumors were floating around that Textron wanted it for the Wildcat XX and Yamaha wouldn’t let them use it.

See @stgdz 's answer above. The 998t with even mild (any) boost would not be classified as an ROV (recreational). That is why the can-am and polaris are 900cc and 935cc powerplants respectively for ROVs. Its all about insurance rates and it starts with legislation. The companies (yamaha/polaris/canam,etc) got together to present a case that under 1000cc should be classified as an ROV and this became the standard and the insurance companies went along with it. The Polaris 1997cc powerplants are considered sand rails, not ROVs so they carry higher insurance rates and cannot be used in some areas. A YXZ with the 998t with even moderate boost would be a sand rail. That doesn't of course stop anyone from putting a tune or turbo on the YXZ, there are lots out there.

 

[74Nitro]

The individual throttle bodies instead of a single is what gave the excellent throttle response.
Well done.

 

[Turboflash]

The individual throttle bodies instead of a single is what gave the excellent throttle response.
Well done.

IMO, the pressurized intake is what eliminates turbo lag, with or without individual throttle bodies.

 

[74Nitro]

IMO, the pressurized intake is what eliminates turbo lag, with or without individual throttle bodies.

But it isn't pressurized on the cylinder side of the throttle bodies. Therefore you want as little of volume there as possible.