No B.S... How much Horse Power?

[HANDSOME]

Look at this vid of the stock dragon vs. the M8 turbo, the dragon climbs as high as the TM8....so was hp equal?

http://www.youtube.com/watch?v=_cf8eKXZc5E

Have you seen the new Mountain Mod Mania 7? There is a Stock Skidoo 800 that Pulled Monster. There were Apex's and Nitros that couldn't pull it...even Product Tester rolled his sled the same day. He eventually made it with his 1200T, but that 800 Skidoo pulled it first tim!!!. If you don't believe it, watch it. it is in the Big Iron Shoot out section or Yamafest section.

It is all dependent upon handling, and getting that power to the ground/Track speed.[/QUOTE]
I liked that video, I have seen the same circumstances alot .... which sled goes better... I dunno they got the same mark lol.

 

[backcountryislife]

I find it funny that you all have got into a pissin match about tubos and na sleds and no one has answered the original post. I think most pump gas m8 kits make around 200 corrected hp.

I thought Eric answered it pretty well even if he didn't adjust the altitude number to an sae adj. number for the turbo, but 192 honest HP at approx 7k should give a good idea of what you'd see.
If Eric is seeing 192 at his shop (he's around 7k or so) I would think you'd be more like 230 or so as a baseline adj #? Somewhere in there?

Of course it's not that simple with a turbo, you have to turn down boost as you drop altitude, so my take is the higher you dyno a boosted sled, the higher the baseline number would be since it doesn't lose as much as an N/A sled, does that make sense to anyone else??

 

[HILCLMR]

WoW !

This question is the reason I am in the middle of a turbo build on my M8. The one thing I see here is the term "sea level." As we all know atmospheric pressure at sea level is basically 14 psi and it degrades from there. I ride at 6-8k and have found that mod motor sleds at altitude have disappointed me and the guys running 8-10 pounds of boost on a stock motor have reigned. I don't know how much boost you can run at sea level but I would surmise it is fairly low before you have some type of combustion failure, either detonation or o-ring failure. Aggressive porting and a larger bore however should just get more efficient at lower altitudes. Maybe I'm wrong here so if I'm incorrect then someone please straighten me out. It seems though that to get a turbo sled to properly run at sea level you would need to lower the compression ratio significantly, which would just counteract the boost?

I used the term "Sea Level" so that we could establish a baseline to look at all the differences between PG, RG, Intercooled, Non-Intercooled and not get into this huge debate about the way sleds are set up or ridden or tuned.
Honestly I thought it was a straight forward question.

 

[sidewinder]

Not trying to start anything, just have done a lot of research on this and understand some of the differences between sea level and elevation. I am in no way a mechanical engineer so I won't pretend but any engine has changes in efficiency based on atmospheric pressure. As stated I ride altitude and only have experience there. On the lighter side, this question seems to be like a tootsie roll tootsie pop and how many licks it takes....The world may never know

 

[Steve D]

I used the term "Sea Level" so that we could establish a baseline to look at all the differences between PG, RG, Intercooled, Non-Intercooled and not get into this huge debate about the way sleds are set up or ridden or tuned.
Honestly I thought it was a straight forward question.

 

[VOHK]

Wow.. Calm down. I leave the computer for a couple hours and hostility. I most certainly wasn't trying to incite a riot... truly just wanted to give some perceptible facts. With respect to Back Country's original question, you sort of answered your own question when you started down the comparison explanation road. Lets stay with the apples to apples thing, and speak to the units you observed, Donovan didn't build many...only few, and they were all otherwise stock, as was the one you observed that I built (Zooks I assume) that is a 6.5 psi unit otherwise stock, this is going some where just bare with me... lets describe Brian's with years of very admirable devotion to the evolution of his build, similar no doubt to many of my more exotic builds, where as virtually every conceivable component has been rethought and if possible refashioned from an alternative and lighter material IE Ti, Delrin, Garlite, various aluminum alloys, etc. (remember who your talking to and about in this case) not to mention the extensive message given to engine and drive components IE head, pipes, porting, intake, reeds, cryo treatments, balance, light drive, light shaft, light rotor, Light hood, Ti fasteners throughout, track, seat, oh heck we could go on and on (don't forget I sold him allot of those parts). Also worthy of mention is the obscene amount of hours it takes to build a sled of that caliber is difficult to overstate. Another very important factor... he can ride... Anyway, the point being apples... so it seems its just a tic out of the realm of common sense and good judgment to use Brian's (orange) as the standard of comparison, sort of like using my (orange) as such. Anyone feel like a piece of fruit?.. oh boy it must be late. And remember this thread was about horsepower not how fast they go up hill... though related, they are not without other considerations. I once watched a stock 800 beat a 20 PSI RX1 in an uphill drag race... should I infer the 800 built more horsepower? Hope this helps answer your question, I didn't mean to imply that a turbo is the end all, only that its clearly the only logical use of money for substantial altitude horsepower gains.

 

[ccpowder]

Have you seen the new Mountain Mod Mania 7? There is a Stock Skidoo 800 that Pulled Monster. There were Apex's and Nitros that couldn't pull it...even Product Tester rolled his sled the same day. He eventually made it with his 1200T, but that 800 Skidoo pulled it first tim!!!. If you don't believe it, watch it. it is in the Big Iron Shoot out section or Yamafest section.

Stock??? LOL I guess a sled with a huge shot of Nitrous is now considered stock?? Well hell, a stock sled with a turbo must also be considered stock.

And I am thinking he was running a 3" track too. When did Ski Doo start putting those on!! I would have bought one this year if I new it came stock with 3" track and Nitrous....

 

[backcountryislife]

Wow.. Calm down. I leave the computer for a couple hours and hostility. I most certainly wasn't trying to incite a riot... truly just wanted to give some perceptible facts. With respect to Back Country's original question, you sort of answered your own question when you started down the comparison explanation road. Lets stay with the apples to apples thing, and speak to the units you observed, Donovan didn't build many...only few, and they were all otherwise stock, as was the one you observed that I built (Zooks I assume) that is a 6.5 psi unit otherwise stock, this is going some where just bare with me... lets describe Brian's with years of very admirable devotion to the evolution of his build, similar no doubt to many of my more exotic builds, where as virtually every conceivable component has been rethought and if possible refashioned from an alternative and lighter material IE Ti, Delrin, Garlite, various aluminum alloys, etc. (remember who your talking to and about in this case) not to mention the extensive message given to engine and drive components IE head, pipes, porting, intake, reeds, cryo treatments, balance, light drive, light shaft, light rotor, Light hood, Ti fasteners throughout, track, seat, oh heck we could go on and on (don't forget I sold him allot of those parts). Also worthy of mention is the obscene amount of hours it takes to build a sled of that caliber is difficult to overstate. Another very important factor... he can ride... Anyway, the point being apples... so it seems its just a tic out of the realm of common sense and good judgment to use Brian's (orange) as the standard of comparison, sort of like using my (orange) as such. Anyone feel like a piece of fruit?.. oh boy it must be late. And remember this thread was about horsepower not how fast they go up hill... though related, they are not without other considerations. I once watched a stock 800 beat a 20 PSI RX1 in an uphill drag race... should I infer the 800 built more horsepower? Hope this helps answer your question, I didn't mean to imply that a turbo is the end all, only that its clearly the only logical use of money for substantial altitude horsepower gains.

That's basically what I was looking for, I know the lightweight stuff makes a difference, but didn't realize that it was that significant in a drag/straight up hill race. I see the lightweight stuff as being more of a rideablilty thing. And yeah, I can give that a sled like Brian's, or even like my little guy are a little beyond the amount of $$/ effort than most folks are putting into lightening them up & tuning them to get the most possible out of them & that $$ would be more likely just as well spent on a turbo. (why I bought one & will buy another...) The biggest thing I notice is felt power & speed up the hill, they just didn't feel like his or a couple others that I've ridden that were done like his. Beyond 10-11 or so psi I think the comparison ends, but that's why I have a RG kit on ours. I'm excited to run it against Brian's sled this year as another friend of mine bought it & see what kind of PSI it honestly takes to compare.

Thanks for the response, I miss the tutorials I used to get when I passed through there every week!

 

[diggerdown]

There is no doubt that there are too many variables between set-ups, riders, and snow conditions to always judge a sleds horsepower by how high it climbs. The question I have is, what is the optimal track speed? In dry powder fluff, will 40 mph track speed climb as high as 60 mph? I've had 40 mph speed and out climbed sleds turning 60 mph but it depends greatly on the snow conditions. On hard pack, I get waxed!

 

[bigbird]

Stock??? LOL I guess a sled with a huge shot of Nitrous is now considered stock?? Well hell, a stock sled with a turbo must also be considered stock.

And I am thinking he was running a 3" track too. When did Ski Doo start putting those on!! I would have bought one this year if I new it came stock with 3" track and Nitrous....

Kyle went over on an XP with clutching and a can, 162, 2.5 CE track. No spray. Corey went over on an 880 Bikeman with spray.

 

[Idcatman3]

Can't get the word file to attach...here is a link to pressure vs altitude.

http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html

Here's a picture of the chart:

 

[RKT]

However that same M8 at my shop on an average fall day made an actual 111.3 HP which when correct to SAE Standards was 140.8. So now consider the same unit with a Boondocker pump gas kit later that same day made 192 actual HP at 7.8 PSI.

While we are keeping it factual and civil.. I suspect this will quickly change but, maybe we can get lucky this time.

Let's push some numbers and theory

First a little theory..

Theory states that an engine should be able to double it's power with a doubling in atmospheric pressure.

So, let's assume that 1 ATM @ sea level is 14.7 so a 100HP engine at 1 ATM would produce 100HP. That same engine at 2 ATM (29.4psi (14.7 x 2) would produce 200HP (double the pressure). So, essentially at 14.7 PSI boost you should be able to double the power of any engine (in theory) . The reality is a bit different.. The real boost pressure to double the HP of an engine is closer to 16psi (this varies also between engines and turbos etc. etc.)

So, hypothetically speaking, if you dyno a STOCK engine at sea level and 1 atm and 60 degree air and get 100HP then you put that engine in 2 ATM of pressure, (adjust fuel etc. ect) that engine should and most likely will produce 200HP.
Now, take that same engine and equip it with a turbo set at 14.7 psi boost.. Will that engine produce 200HP? IMO, no... it will produce less.. why? That is a whole other discussion, but the simple answer is parasitic losses due to upset 2 stroke pipe effects, hotter air, and a few other factors. Hence some of the reasons why a turbo is preferred on 2 strokes vs. a Super Charger Set up.

OK, I think we can all agree that HP/psi-boost is NOT linear. meaning.. if you make 100HP on 10PSI boost, at 1 PSI boost you are not making 10HP (100/10). BUT from , say 10-11 psi you could be making 10HP gains.

I think we can also agree that different turbos and their associated designs and compressor maps get "happy" at different boost levels. So, the design of the turbo is a big player in determining where it fucntions the best. I think we can agree that nobody design a turbo system to be optimum at low boost levels like 1-5 psi..

So, we can assume that at the lower boost levels, the turbo is not producing the same kind of power increases that it is at the higher boost levels (when it is in its optimum area) So, from , say 8-14psi, the turbo is, most likely, running at it most optimum levels (of course this varies with turbos)

So, back to the theory.. double the atm pressure,double the power..

So, given the example above.. we have an engine that makes 111.3HP so theory would tell you that at 14.7 boost pressure that engine should produce 222.6HP but, factor in the losses and this would be closer to 16PSI boost to make the 222.6HP.. But let's call it 15 PSI just to have a whole number.

So, with example numbers.. 192HP@ 7.8PSI boost so 192-111.3 = 80.7HP on 7.8PSI boost or 73% more power.. So, this example shows that 73% of the power is made in the 1st 7.8 psi of boost pressure. considering, that the first 1-5 PSI the turbo is not operating in its "optimum" range... this is an outstanding accomplishment!

So now consider race gas kits with mild modifications pushing up-wards of 16 PSI capable of 300+ actual HP.

This is another quoted example.. So, the 140HP sled at 16PSI is now making 300+ HP If theory holds and is 100% accurate at 15PSI this same sled would make only 280HP (140 X 2). So, 1 PSI boost in this scenario is producing upwards of 20HP. Again, an outstanding accomplishment..

BUT.. if you can agree that there are losses associated with the turbo system (like I mentioned above) then these numbers are truely outstanding.

So, my question, since we are keeping it factual is:

1) How can the engine be producing more power than "Ideal" Laws of Physics can explain?

Keep in mind we are NOT dealing ,in reality, with ideal conditions..

Great discussion.. Let's try and keep it on topic and civil..

Kelsey

 

[Lucky Lyle]

Lets make a new rule If you dont tune and ride /own a turbo you cant comment or awnser questions related to them. (nothing beats side by side compareison) and I have never seen a dyno move through the snow, or any turbo system that was exactly the same hp at the same boost every little change will affect hp, and the effect on the dyno will be diffrent on the snow!!!!!!!!!!!!! with the tecknology progressing everyday pipes,fuel control and numerous other things, some things that work at 5 to 10 #s of boost do not work at 10 to 15#s but most of the things that work at higher boost work even better at low boost. in the end here is what matters.
at high elevation nothing compensates like boost. and nothing will make you smile like loading in the trailer day after day after running boost!!!!!!!!!!!!!!!!

 

[Pastor]

RTK

Is it not true that since you are riding for sake of illustration 10,000 ft the atmospheric pressure is no longer 14.7 lbs it may only be around 10 lbs.

(Understand that I am not saying I am right, I am just sitting here thinking.)

Therefore to double the hp of that motor you no longer need 15 lbs boost about 11 lbs boost would do it at 10,000 ft. (That 150 hp motor loses 1/3 hp at 10,000 ft and now has 100 hp and with about 11 lbs boost now makes about 200 hp at 10,000 ft.)

Now, if that engine were capable of 140 hp at sea level and capable of 15 lbs boost without blowing up and about 280 hp at sea level then you have two atmosphers of pressure in that motor.

It would stand to reason in my mind then that the same engine could take 20 lbs boost at 10,000 feet added to the aproximate atmospheric pressure of 10 lbs you now theoretically have your 280 hp but now at 10,000 ft. and the motor should be able to take it with the same fuel required at sea level for 15 lbs boost.


I am no expert, just sitting here trying to understand, and I have probably missed something obvious.

 

[RKT]

pastor..

Great question and I asked that exact same question in my previous post.. Hopefully Karl will supply us with the correct answer.

In all honesty, I think there are really no accurate calculation when dealing with a 2 stroke turbo. Just a slight change in pipe design can drastically change HP. So, the variables become increasingly unknown in a big hurry..

I also think that will a dyno test that you need to run no correction factors inthe dyno software since the dyno extrapolation is based on atmospheric conditions and with a turbo you no longer really have atmospheric conditions, so any dyno corrections would be inaccurate because it is not designed to calculate around those conditions. Just a thought.. not sure if it is accurate or not.

RTK

Is it not true that since you are riding for sake of illustration 10,000 ft the atmospheric pressure is no longer 14.7 lbs it may only be around 10 lbs.

(Understand that I am not saying I am right, I am just sitting here thinking.)

Therefore to double the hp of that motor you no longer need 15 lbs boost about 11 lbs boost would do it at 10,000 ft. (That 150 hp motor loses 1/3 hp at 10,000 ft and now has 100 hp and with about 11 lbs boost now makes about 200 hp at 10,000 ft.)

Now, if that engine were capable of 140 hp at sea level and capable of 15 lbs boost without blowing up and about 280 hp at sea level then you have two atmosphers of pressure in that motor.

It would stand to reason in my mind then that the same engine could take 20 lbs boost at 10,000 feet added to the aproximate atmospheric pressure of 10 lbs you now theoretically have your 280 hp but now at 10,000 ft. and the motor should be able to take it with the same fuel required at sea level for 15 lbs boost.


I am no expert, just a thinker, and I have probably missed something obvious.

 

[hatchers]

Lets make a new rule If you dont tune and ride /own a turbo you cant comment or awnser questions related to them. (nothing beats side by side compareison) and I have never seen a dyno move through the snow, or any turbo system that was exactly the same hp at the same boost every little change will affect hp, and the effect on the dyno will be diffrent on the snow!!!!!!!!!!!!! with the tecknology progressing everyday pipes,fuel control and numerous other things, some things that work at 5 to 10 #s of boost do not work at 10 to 15#s but most of the things that work at higher boost work even better at low boost. in the end here is what matters.
at high elevation nothing compensates like boost. and nothing will make you smile like loading in the trailer day after day after running boost!!!!!!!!!!!!!!!!

great post

numbers, shumbers.....its all engine size/compressor size/turbine size/charge tube/injectors and location/track/weight/elevation......yada yada yada

Understand I work with a few Bazillion dollar dynos at sea level....then we set these engines up at 5-10K and stuff changes....math is fun to learn and play with, but my (we/me/my employeer) still cant sell dyno sheets, oh we try, lord do wew try

 

[RKT]

Let's get this all straight. I am an engeer and there are better snowmobile tuners, but I have a pretty good nack for blending theory and real life.

1) Look at my equation above. Scalling with pressure only will work as long temps don't vary much. At low boost, temps are not so bad. As you increase boost it gets important to start using the temperature scaling method. Remember, just like you use an absolute scale when using pressure, use an absolute scale when scaling with temperature. That is, convert farenheit to Rankine...that is easy just add 460...things will start to make more sense at high boost. So you can take into account temperature.

Making engineering modifications is rarely done without trade offs. I am sure adding a turbo is not 100% perfect since the engine NA form has done some trade offs for things like emissions, gas mileage, reliability, cost etc...so a turbo will have some down side losses. At lower boost I think that is relatively minor and that is shown by the equations working quite well for this. At high boost, you have to start worrying about pressure loss through an intercooler, charge temps, backing out of the compression, etc...soon the extrapolation gets too big and you have more oranges than apples...If I had computational fluid dynamics capability I could model this quite accurately. I was just providing some basic tools so the lay person could decide which way he wanted to go with the mods.

2) I see your point and you have made this before on other threads. Once again I am going to say close to lower boost probably not so bad. Clearly, compression can change and more optimum port timing can make a turbo system better, I am not sure what can be done about the pipe, but two strokes do need a restriction to work and that is why superchargers don't work for two strokes. You just can't trap the charge with a supercharger. But pressure waves bouncing off the turbo are needed and the restriction is not entirely negative.

Keep in mind that engine mods are not without trade offs. Higher compression means better efficiency, but pumping losses increase at higher rpm. Bigger pistons mean lower volumetric efficiency so there scaling an engine horspower on displacement is not quite linear either.

3) Convert all pressures to absolute pressure at the elevation you are using. Scale using absolute presures only for the calculations. So at sea level use 14.7 plus boost and at 10,000ft use 10.1 plus boost. You can use linear interpolation between values on the chart above without too much error. To be accurate factor in temperature. For NA I think you are fine without, but the air does get warmed. Use temperatures and pressures in the intake plenum. Not outside air or pressure before a restrictive intercooler.

4) No, I think scaling with pressure and temperature is very accurate for NA and low boost. It is not perfect but numbers I get are close. As boost increases and engine mods are added to overcome problems, extrapolation error increases...but still...not so bad...

5) I ran VOHK's numbers last night. There is some missing info since I do not see his elevation and I assumed his shop was temperature controlled. To get a horsepower drop from 140 sea level 60 degrees to 113, his shop needs to be at about 6800 feet elevation and maintained at 60 degrees also. When I use this info to calcultate the turbo numbers I came up with 190 hp, so theory agrees, but I could not compensate for temperature and I don't have a feel for temps on a short dyno pull nor do I know if he backed out on compression. I think his numbers are accurate. Dynos can vary also so I am calling differences of 5 hp minor. I think he is in the ball park and numbers of 200 hp for pump gas turbos makes walking around sense especially coupled with elevation losses. An elevation in colorado at 6800 seemed close too.

I think there is a cross over line with altitude, If I was at lower elevations I like bb torque. WWII engineers can not be doubted. There is a point that making bigger pistons will not make fighter aircraft faster and you have to add a supercharger.

I am leaving my BB ultra this year, the motor ran when it ran, but it was finicky at altitude, I am testing out a TM8 this year to see if it runs more consistently at elevation. Maybe the torque of a 1200 big bore is more like my boondocking riding style...It was a little cheaper to run the turbo tho so I am trying it first.

Thanks for the info..much appreciated...

One other thing to consider with a turbo that will play into the calculations.. is that no matter how hard you try and force air through an engine, if it can not flow the air properly, then it can not make proper use from it..

This is MUCH more apparent with a 2 stroke engine than a 4 stroke engine because the intake and exhaust ports are piston controlled and the means to avoid short circuiting are next to nothing (this is where the pipe effects play a huge role). Of course, with a 4 stroke you do not have ANY of these short circuiting issues..so power rises more quickly and stays more stable. Calculations work much better. 2 strokes get uphappy very quick with any slight change.. Point being.. just because you feed a 2 stroke engine more air,via turbo, does not mean that it can make use of ALL the added air supplied. There comes a point where the added power per amount of added air becomes low simply because the system is overloaded. This is where the porting play a huge role. This is also why I think some turbo kits work better than others on different engines... Some engines can simply flow more air more efficiently.
So, the calculations are based on the engine being able to take full advantage of the added air (4 stroke). With the 2 stroke...again.. there are added variables to throw in the mix..

Another thought... We do not run 60 degree air in the Winter..

Again.. thanks for the insight..
Kelsey

 

[HILCLMR]

BS....

Sooooo.....No ones ever dyno'd their Turbo M8?

 

[VOHK]

Pernikm, great data! I had really tried to steer away from the truly technical aspects of this argument and relay info in a palatable fashion for the lay, as it seems likely to be outside the parameters of what most members would be willing to expel in terms of critical thinking efforts. And who would blame them.. they just want to ride and leave the bean counting, number crunching data analysis to geeks like us that otherwise have that calling...Please don't take that with offense, just very few feel compelled to crawl far down the rabbit hole.

 

[Radski30]

Lets make a new rule If you dont tune and ride /own a turbo you cant comment or awnser questions related to them. (nothing beats side by side compareison) and I have never seen a dyno move through the snow, or any turbo system that was exactly the same hp at the same boost every little change will affect hp, and the effect on the dyno will be diffrent on the snow!!!!!!!!!!!!! with the tecknology progressing everyday pipes,fuel control and numerous other things, some things that work at 5 to 10 #s of boost do not work at 10 to 15#s but most of the things that work at higher boost work even better at low boost. in the end here is what matters.
at high elevation nothing compensates like boost. and nothing will make you smile like loading in the trailer day after day after running boost!!!!!!!!!!!!!!!!

Hey if your NOT a member or soon to be member of the Twisted Nation, then your not allowed to post here!!!

Lucky Lyle and Product Tester are in charge.