Power to weight ratio or just power?

Couch · Feb 23, 2020

lilduke said:
I never said you have to build it like a tank or there isn't any places to lose weight.

like shot for example, you know what's lighter than that? pull start, I've been running that for over 20 years lmao

Pull start as well so guess im laughing too but would take Shot over conventional e start.

...well engineered to be light and strong ...at some point with the right hit something will / has to give. Adding braces sometimes means that you simply transfer the failure to another spot - reinforce the a arm and break a bulkhead instead - I'll take the hit to the a arm every time - cheaper and quicker / easier to fix.
Yes there is a balance point at which you remove more weight and strength begins to be compromised at which point you can attempt to re-engineer or use more exotic materials or simply establish it as the floor / minimum acceptable and move on. With current sleds there is still room to improve vis-à-vis reduce weight.
Have loads of fun on my 600 and 800s but i ride 100' to 2500' in trees so boost / more power is not top of my list - less weight is as I can then ride longer and harder.

lilduke · Feb 23, 2020

Couch said:
Pull start as well so guess im laughing too but would take Shot over conventional e start.

...well engineered to be light and strong ...at some point with the right hit something will / has to give. Adding braces sometimes means that you simply transfer the failure to another spot - reinforce the a arm and break a bulkhead instead - I'll take the hit to the a arm every time - cheaper and quicker / easier to fix.
Yes there is a balance point at which you remove more weight and strength begins to be compromised at which point you can attempt to re-engineer or use more exotic materials or simply establish it as the floor / minimum acceptable and move on. With current sleds there is still room to improve vis-à-vis reduce weight.
Have loads of fun on my 600 and 800s but i ride 100' to 2500' in trees so boost / more power is not top of my list - less weight is as I can then ride longer and harder.

Use what ever works for you, but what works for you might not work for me. So I guess thats why we have choices....

Teth-Air · Feb 23, 2020

lilduke said:
I think his point was the Rider will effect the Power to weight ratio. The Heavier the rider and gear the more effect it will have on that ratio.

Sleds dont just ride around by them selves.

Good point.

Teth-Air · Feb 23, 2020

Couch said:
Pull start as well so guess im laughing too but would take Shot over conventional e start.

...well engineered to be light and strong ...at some point with the right hit something will / has to give. Adding braces sometimes means that you simply transfer the failure to another spot - reinforce the a arm and break a bulkhead instead - I'll take the hit to the a arm every time - cheaper and quicker / easier to fix.
Yes there is a balance point at which you remove more weight and strength begins to be compromised at which point you can attempt to re-engineer or use more exotic materials or simply establish it as the floor / minimum acceptable and move on. With current sleds there is still room to improve vis-à-vis reduce weight.
Have loads of fun on my 600 and 800s but i ride 100' to 2500' in trees so boost / more power is not top of my list - less weight is as I can then ride longer and harder.

Light weight with lots of power to weight ratio is my choice too because I like the idea of not being as tired handling a heavy beast all day. Also the N/A sleds are simple and have best bottom end torque which is idle for tree riding. (Not saying all turbos have bad bottom end torque because the Doo is pretty good in that dept.) Some will say they have no problem handling the weight of their sleds but how would your ride feel if it was 50 lbs lighter? I don't care what brand, they are all heavy if you roll it into a tree well. For me I'm not sure if adding a turbo is worth the weight until all other methods of performance are exhausted. e.g. best clutching, best gearing, lightest weight, biggest bore. Then add the turbo if you need more.

Heimie · Feb 23, 2020

I agree with what guys are saying about getting a whole lot lighter may compromise durability.

That being said, I don't think I need more power, just more talent!

Also, when I get stuck (which rarely happens, LOL) rolling over a 450 pound sled vs. rolling over a 550 pound sled, or trying to maneuver a heavier vs. lighter sled out of a tree well, or whatever, I'm sure I would notice the weight.

Bikeswithtrax · Feb 23, 2020

RGM said:
Putting a 250lb guy and 50 lbs of gear on a 400 lb sled vs on a 575 lb sled with same power to sled weight and the 575 lb sled will walk over the 400 lb one.

That is a really big guy, who did bring the kitchen sink along to.

For me, the 400 pound sled all day long. Power is one thing, but flickability is more important to me.
A can alone is about a 10 pound weight reduction, and cheap. On most sleds it is super easy to take 20 pounds off of them, and add 20 hp. So if you use the example of an 850 RMK, you already have good power, so add 20 more, shave off 20 pounds, go on a diet and get yourself down a bunch, and boom, great sledding!
By the way I am over 6'1" and weight is 186...i could drop another 5 no problem. And i can't even imagine what the heck I would pack along to add 50 pounds, and I sure would not want to try and ride with a 50 pound backpack strapped to me. My pack starts the average day out at 16 or 17 pounds, and once I eat and drink some of the stuff, the weight just keeps going lower.

niner · Feb 23, 2020

Where are you guys buying these 400 lb sleds? Cost you $50000 to build a 400 lb sled.

oler1234 · Feb 23, 2020

would have thought the polaris 163 would be lighter than those weights given they list the dry weights drastically lighter than all other brands.

niner · Feb 23, 2020

oler1234 said:
would have thought the polaris 163 would be lighter than those weights given they list the dry weights drastically lighter than all other brands.

https://youtu.be/_2D8Kay99kc

RGM · Feb 23, 2020

LOL 5 gal jug of gas weighs 35lb by itself. You don't think the rest of your gear weighs 15lbs?

RGM · Feb 23, 2020

A 400 lb sled with 150HP is 2.66lbs/hp add a 250 lb rider and 50lbs that increases to 4.66lbs/hp a 575lb sled with 215 hp is 2.66lbs/hp add same rider and gear it increases to 4.06lbs/hp. Don't you think you would notice a 15% diff in lb/hp?

jhurkot · Feb 24, 2020

580lb electric sled that delivers 180hp to the track at all elevations.

Rotax_Kid · Feb 24, 2020

There is a happy medium here and always a trade off pick your poison...

If it's light, it might not be durable

If it's durable, it might not be light

If it's durable and light, it's going to be expensive

If it's durable, light, and even more powerful, it's going to be even more expensive

Current machines are already stretching the boundaries of production level engineering and cost/volume capability. Snowmobiles are such a unique product with you think about it. Quads and Watercraft aren't overly concerned about weight. Guaranteed BRP has looked at how to integrate a machine that is built somewhat like a Spark into the line, but it probably came out heavier than they wanted. Engineering stuff like this is complex - the end user wants it light. You can only FEA and minimize areas so much as the end user doesn't want a tiny bend or dent to become a major stress concentration and implode the rest of the machine. Same goes for repair procedures - what are you willing ot pay to have technicians who need increased training to try reassemble these things and maintain the appropriate design factors of safety?

For reference, here's a interesting Power to Weight chart from Wikipedia...Consider we are in F1 power to weight territory. Those are handbuilt engines that are only designed to run for a few hours at a time. We demand 4 year warranty, in a machine that bounces, or rams into whatever the rider can throw at it, at F1 performance, with container ship durability...crazy huh?

/ type	Peak Power Output	Power-to-weight ratio	Example Use
SI	English	SI	English
14-cylinder [SUP][3][/SUP]	80,080 kW	108,920 hp	0.03 kW/kg	0.02 hp/lb
538 cc V2 petrol [SUP][4][/SUP]	19 kW	25 hp	0.27 kW/kg	0.16 hp/lb
//0032-28 Mod 2 502 cc petrol [SUP][5][/SUP]	62.3 kW	83.5 hp	0.30 kW/kg	0.18 hp/lb	[SUP][•][/SUP] 1985
6.6 L [SUP][1][/SUP]	246 kW	330 hp	0.65 kW/kg	0.40 hp/lb	,[SUP][•][/SUP] [SUP][•][/SUP]
two-stroke, Diesel, [SUP][6][/SUP]	647 kW	867 hp	1.1 kW/kg	0.66 hp/lb	,
marine [SUP][7][/SUP]	30,200 kW	40,500 hp	1.31 kW/kg	0.80 hp/lb	,
1.3 L [SUP][8][/SUP]	184 kW	247 hp	1.5 kW/kg	0.92 hp/lb	[SUP][•][/SUP]
71.5 L 28-cylinder ()	3,210 kW	4,300 hp	1.83 kW/kg	1.11 hp/lb	, , , ,
54.57 L 18-Cylinder Radial engine	2,535 kW	3,400 hp	2.09 kW/kg	1.27 hp/lb	,
49-PI Type II 4.97 cc [SUP][9][/SUP]	0.934 kW	1.252 hp	2.8 kW/kg	1.7 hp/lb	, ,
JetCat SPT10-RX-H [SUP][10][/SUP]	9 kW	12 hp	3.67 kW/kg	2.24 hp/lb	,
marine [SUP][11][/SUP][SUP][12][/SUP]	44,700 kW	59,900 hp	5.67 kW/kg	3.38 hp/lb
V10 3L P84/5 2005 [SUP][13][/SUP]	690 kW	925 hp	7.5 kW/kg	4.6 hp/lb	car,[SUP][•][/SUP] auto racing
i4 1.490L M12 engine 1987 [SUP][13][/SUP][SUP][14][/SUP]	1030 kW	1,400 hp	8.25 kW/kg	5.07 hp/lb	car,[SUP][•][/SUP] Formula One
/AE1107C [SUP][15][/SUP]	4,586 kW	6,150 hp	10.42 kW/kg	6.33hp/lb
supercharged V8 ()[SUP][16][/SUP][SUP][][/SUP]	8203 kW	11,000hp	36.46 kW/kg	22.2 hp/lb	US Army Top Fuel Dragster
Block I H[SUB]2[/SUB] [SUP][2][/SUP]	53,690 kW	72,000 hp	153 kW/kg	93 hp/lb

For Electric Motors...

type	Weight	Peak Power Output	Power-to-weight ratio	Example Use
SI	English	SI	English	kW/kg	hp/lb
Kawak 4kW 28VDC [SUP][17][/SUP]	11.8 kg	26 lb	4 kW	5.4 hp	0.29 kW/kg	0.18 hp/lb	Flight-rated motor for aircraft auxiliary systems (fuel pumps, etc.)
MSMA202S1G [SUP][18][/SUP]	6.5 kg	14 lb	2 kW	2.7 hp	0.31 kW/kg	0.19 hp/lb	,
Kawak 7.5 kW 208 VAC 400 Hz 3-Phase [SUP][19][/SUP]	11.8 kg	26 lb	7.5 kW	10.1 hp	0.47 kW/kg	0.29 hp/lb	Flight-rated motor for aircraft auxiliary systems (fuel pumps, etc.)
660 MVA water cooled 23 kV AC	1,342 t	2,959,000 lb	660 MW	890,000 hp	0.49 kW/kg	0.30 hp/lb	,
Canopy Tech. Cypress 32 MW 15 kV AC [SUP][20][/SUP]	33,557 kg	73,981 lb	32 MW	43,000 hp	0.95 kW/kg	0.58 hp/lb	Electric
motor[SUP][21][/SUP]	36.3 kg	80 lb	50 kW	67 hp	1.37 kW/kg	0.84 hp/lb	[SUP][•][/SUP] 2004
Himax HC6332-250 [SUP][22][/SUP]	0.45 kg	0.99 lb	1.7 kW	2.3 hp	3.78 kW/kg	2.30 hp/lb
HPD40 [SUP][23][/SUP]	25 kg	55 lb	120 kW	160 hp	4.8 kW/kg	2.92 hp/lb	QED ,
ElectriFly GPMG4805 [SUP][24][/SUP]	1.48 kg	3.3 lb	8.4 kW	11.3 hp	5.68 kW/kg	3.45 hp/lb
YASA-400 [SUP][25][/SUP]	24 kg	53 lb	165 kW	221 hp	6.875 kW/kg	4.18 hp/lb	,
ElectriFly GPMG5220 [SUP][26][/SUP]	0.133 kg	0.29 lb	1.035 kW	1.388 hp	7.78 kW/kg	4.73 hp/lb
Remy HVH250-090-POC3 [SUP][27][/SUP]	33.5 kg	74 lb	297 kW	398 hp	8.87 kW/kg	5.39 hp/lb
TP POWER TP100XL [SUP][28][/SUP]	7 kg	15 lb	75 kW	101 hp	9.0 kW/kg	5.5 hp/lb
[SUP][29][/SUP]	19.9 kg	44 lb	230 kW	310 hp	11.56 kW/kg	7.03 hp/lb

Keep in mind - electric motors I believe are just that - motors without a power source. Add batteries into this.

What is the heaviest part of a snowmobile? The Rider. If you were very conscious of how you rode, you could change the machines C of G substantially in changing your riding habits. Your Avy pack - is it full or do you keep alot of your gear in a tunnel bag? 5-7 extra pounds an additional 4ft in the air is a substantial change in vehicle dynamics when it accounts for 1-2% of total machine mass. If the weight is the weight, and we may not be able to get "a-weigh" (great pun eh? thought of it by myself...) from this, the next biggest change is C of G and, and indirectly, how it affects Inertial moments..aka - how fast you can accelerate in any direction...aka for the white rimmed onesie riders..the "flickability."

mountianguy · Feb 24, 2020

jhurkot said:
580lb electric sled that delivers 180hp to the track at all elevations.

Sidewinder not electric but similar power and weight

niner · Feb 24, 2020

mountianguy said:
Sidewinder not electric but similar power and weight

Actually the turbo free ride would be closer. Should weigh 570 lbs and 165 hp. Sidewinder is 654 and 180 hp

lilduke · Feb 24, 2020

fair to note the gas sled will loose some of that wieght as you burn through the gas and oil.

vodoo103 · Feb 24, 2020

niner said:
Where are you guys buying these 400 lb sleds? Cost you $50000 to build a 400 lb sled.

Is this where this thread fell off the rails?

lilduke · Feb 24, 2020

vodoo103 said:
Is this where this thread fell off the rails?

I think so. for a while there we were pretending that Polaris is 175lb's less than a turbo doo. when it's more like 25lbs lol

jhurkot · Feb 24, 2020

lilduke said:
fair to note the gas sled will loose some of that wieght as you burn through the gas and oil.

Yes but also fair to say that you lose half the power to drivetrain inefficiencies.

lilduke · Feb 24, 2020

jhurkot said:
Yes but also fair to say that you lose half the power to drivetrain inefficiencies.

What kind of track HP will the electric one have you figure? Probably a better place to measure than the motor for a real comparison.

It will have driveline losses too, but could be significantly less forsure.

Power to weight ratio or just power?

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