impeller mod

Bike modifications and general wrenching advice.
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tmsteves70
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impeller mod

Post by tmsteves70 » Wed Dec 20, 2017 5:29 am


Picture of the H2 impeller show that it looks like it's just bolted on to the impeller shaft. I don't know if this is true or not, but what are the possibilities of a straight swap with an H2 impeller? would any other mods need to be done to the h2 sx to accommodate, like remapping etc? Or is increasing the boost pointless without chaning much of the top end? :scratch:

The concept of forced induction on a motorcycle is foregin to me. :wtf:
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cOoTeR
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Re: impeller mod

Post by cOoTeR » Wed Dec 20, 2017 2:05 pm


If you change boost you're definitely going to have to remap. Also the compression ratio is different between the 2 bikes which will have a effect on how the engine responds to boost. They say these are similar engines to the H2 but they are very different. The cams, heads, pistons, crank, exhaust are all different as well and each are major parts when it comes to how the engine runs.

Also from what I've seen they don't sell just the impeller. I've only been able to find the entire compressor listed on the parts diagrams as a part to buy and that costs over $3k US.

I did a quick estimate just pricing out the parts the magazine's were listing as different between the H2 a ff the H2 SX motor and it was over $9k in just tee Martin parts alone. Not including labor, small parts needed for the changes and shop supplies. Its on this forum.
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Re: impeller mod

Post by cOoTeR » Wed Dec 20, 2017 2:43 pm


Also you can change boost by changing out the supercharger gears. It's a common mod on the H2. But that can get risky. As performance goes up the life expectancy of the engine goes down.
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kman0066
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Re: impeller mod

Post by kman0066 » Wed Dec 20, 2017 2:45 pm


The top-end is less-important than the bottom-end on the higher boost of the the different impellers. The H2 uses forged, low-compression pistons and the SX uses cast, high-compression pistons. The SX pistons, more like a standard bike's pistons, which can handle some moderate boost, but if you start stressing them too much with higher amounts of boost, they will fail, especially if pre-ignition starts happening. On the other hand, the higher compression leads to a much more efficient engine, so we get the better MPG.

So, you could change over to the forged pistons, but then you have a problem in that the rotating assembly needs to be balanced and the crank is where you would balance it. The weight between forged and cast pistons is significant and to balance it properly, you would probably be better off buying the H2 crank.

The other worry about the bottom end is oiling. They are running less oil through the SX than the H2 because of the less-stressed engine. If you stress the engine more and don't do something about oiling, you may have HUGE problems. And that design change is not only in the oil pump, but the engine block itself.

Then yes, you would need to re-map the engine.

To get the very most HP, it would be better to have the H2 head and cams, but they wouldn't be necessary to achieve higher boost numbers specifially. The H2 head flows more air (less MPG) and the cams are designed for HP (focus on high-RPM power), not ride-ability mid-range like the SX.

My thoughts, if you want to build an ultimate HP beast, go find a left-over H2. There's a lot of deals on still new 2015-2016 models that makes them the same price (or even better) than the SX. If you want a street/tour-bike that has a stupid amount of power for a street-bike, that's what the SX is for. I think an ECU tune and exhaust are going to take this thing to a lot higher numbers than stock (Maybe 230???). But to get to that 250-275hp level, you're better off just buying the H2 and working on it.


That all said, maybe it will work. It's not going to be ideal because of what all I said above. It's not going to be a long-mileage motor anymore, but if you just want to build a drag-bike out of it, get a conservative tune built with it so that pre-ignition is limited, it just might work...but not a risk I'd take with a $22k bike.
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tmsteves70
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Re: impeller mod

Post by tmsteves70 » Thu Dec 21, 2017 2:17 am


Thanks for the insights. I'm just curious how much this engine will be able to be pushed with respect to the H2 or what will be the biggest bang for the buck while still maintaiing reliability.
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