[TT670]

Im not aware of an engine identified as a 380HO in a sled application. If there was one id be interested in knowing what machine it came in.

 

[TT670]

It may exist overseas but never in the us. I've followed ski models pretty darn closely for decades and its one model I've never heard of. In fact the only HO models I ever recall ski doo building were the 600, 670 and 800 and the first season the HO designation was used was the 1999 model year on the 670.

Here's the American 2004 spec sheet

http://www.ski-doo.com/Archives/archives_2004/pdf/spec_sheet_mx_z.PDF

 

[TT670]

I think the point is, if you're looking for info on a 380 HO, your odds of getting it from someone in the US is slim.

You are correct, the 670Ho was introduced in limited numbers in the 1998 summit X and across the lineup in 1999. I forgot about the 98 summitX being a flatlander.

The 800ho was released in only summit models in 2003 and across the entire line up in 2004 got 1.8mm higher exhaust ports and a couple other small changes I don't recall.

The 600HO, introduced in 2003 was a completely new series 594 engine, based on the earlier 700 bottom end and was given the HO designation to separate it from the previous 597 series 600 that was originally based on the 440/500 bottom end.

 

[TT670]

670HO cylinders are quite different from the standard 670. The rear boost port is 17mm taller, the transfers are 8mm wider and the exhaust port is 22mm wider. HO exhaust port timing is 203/134 and non HO port timing is 200/130. The lower case on the HO also has some CNC work done to change the shape and slightly enlarge the tunnel port and Im pretty sure the compression ratio is 11.8:1

non Ho horsepower was typically around 117-119, while the HO was 128-130.