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

KAWGRN said:

Those of us who ocassionally ride the flat lands will relate to this since I used to drag race and have been clutching sleds for a long time (yes Im old) you can ALMOST interpolate a horspower by looking at the clutch weight, By that I mean that at sea level where everything is corrected to you know your Hp there . for example a dragon is supposed to make 150 hp (mabe) and the rule of thumb 33% loss at 10,000 feet You roughly have 110hp your seeing,,,, I know this because at sea level I may pull 74 gram arms at sealevel or 600 feet in the Up of michigan,, but at Vail pass only pull like 56-60 grams ,yes I know the helix and spring and gearing combo make alot of difference too,, but roughly speeking,, now I install my turbo on my dragon and clutch it at 10k and guess what?? Im pulling mabe 70-74s at 12psi so how much power do I have ???? Im betting not the 200-250- every one claims more like like 150-175 ,,the sled shure feels like it ,,,I know because I know what it feels like at 600 feet just a week earlier(I have a dragon121 at 600 ft) You can call around and see what weights every one is running at sea level,, I think a turbo is a great high altitude compensator!!LOL thats why I run 12 psi,, at that HP level the motor feels like Im used to in the flat lands 14-16 feels like one of my ported and piped mod sleds in the flats. I had a a Hoopper 3 cylinder cat that made 234Hp at midwest Dyno (cousin to Dyno tech) and I can honestly say that it takes 18Psi on my Dragon to come close to the tug on the bars that thing had , and Im not shure My 2871 garrett will last at those boost pressures I know an AERO wont even go there ,,not to mention my rings, any way this is just my seat of the pants Dyno Talkin cuz every one of those dynos Dyno

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the 2871 should live there just fine at 18lbs. In fact there are a couple of 2871 variants that maps out into the 3.0+ range. You'll have to feed it very good fuel or lower ther compression ratio some as far as the motor goes. Different or reinforced pipe and gasket work. Compressor ratio comes out at around 2.8 for around 9k feet and arount 2.2 at sea level. There are educated guesses and not absolute. Need temp and barometric pressure for absolute numbers.

Its the upper end of the working range but not out of range, assuming there isn't an issue with surge. If surge is an issue, just put on an anti-surge compressor housing. I doubt that would be the case though, unless nitrous was involved.

But at that point, a 3071 or 2876 may be more desireable. If your actually going to run that kind of boost.
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naw ,,,,,,,,Im to old for that kind a boost I just wanted a nice reliable boondocking sled and at 12-14 I got it,,,,,any more that that I start splitting my welds on my pipe,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,but I have this nob on my dashhhhh

Will like to enlight som issues with the backpressure on turboed 2 strokes.

I had a Aerocharger 53 capable for 225hp on a Rev 800 earlier.Witch a buddy of mine dynoed to 210hp at max in a Rev 800.

There was litle powergain up to 6psi but very good powergain from 8-10psi.And little again from 10-12psi where the turbo was maxed out.
Reason for this is that the backpressure was to litle belowe 8psi and was at the sweetspot at 10psi. Above 12psi there was problem to get it to last because of high backpressure and this caused the piston to heat up.
Also the compressor is out of the efficient range above 12psi, charging the engine with hot air.

In a M8T with a GT 2860R the turbo will have a bigger sweetspot than the 53 turbo. My calculation says you will be best off using 10-14psi boost, above 16 psi the backpressure will build up rapidly and limit the hp.Belove 10 psi the air will go straight thru the engine because of to litle backpressure and not be able to trap the air in the cylinders.This is at sealevel,at higer elevation this will hapends at lower boost settings.This turbo will be maxed out at about 280hp at sealevel in a M8T.
Putting a 53 turbo on a M8, and you probably dont get above 200bhp at max at above 12psi because of the stock porting configuration...And you get 200bhp at 9psi with the Gt2860..

A bigger turbo and the sweetspot will be at higer boost.

In a 2 stroke turbo,the bacpressure will be your enemy and at the same time the main reason for making power.Its very critical to make a good turbochoice for what hp level you are aiming at.

pernikm said:

OP has spoken, I deleted my posts. Sorry to all I have offended.

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That's too bad. Forget what the OP wants, some of us like the drawn out technical discussions.

Sure beats the drama queen stuff.

A few of you post good info, you are the ones who didn't get their feelings hurt by what the last guy wrote.

Its not about what others think how it runs but maybe what you can afford. If a turbo isn't in the budget buy a pipe. haha Like the one guy said let your butt be the dyno.

For the tubo haters I will say this..... I live at near sea level, should I take my turbo off my diesel when I pull up to the mountains since it doesn't help?

hhhhhhhmmmmmmm.....

A note of thanks

Just wanted to thank all of you guys who have the techinical expertise to dissect this turbo discussion. I have learned a ton by checking in and this is a tremendously valuable thread to someone who is homebrewing a turbo kit. One thing I have hard a hard time coming up with is the efficiency numbers for a two stroke so that I can plot my desires on a compressor map. If any of you out there can help in this area it would be greatly appreciated. I am running an m7 with 800 kit shooting for 210 +/- hp at 10 psi boost around 8k elevation. I have guessed at the pressure ratio get around 2.2 but would welcome someone to give me a better or more concrete number.

The best numbers I can find for volumetric efficiency of a two stroke is slightly over 1. I'm using 1.05-1.1 for my calculations.

While we can compare all of these numbers while holding temperature constant, you really need to do an density altitude calculation with temperature factored in to compare 10 degrees in the mountains to 60 degrees on a dyno.

The other thing no one seems to discuss is the exhaust housing aspect ratio that is being used. You can shift the spool time and top end horsepower by altering the aspect ratio. What A/R housing is everyone starting with?

http://wahiduddin.net/calc/density_altitude.htm

This is a pretty good explanation of density altitude

.60 on 2860 for 9k+ use applications 7-14 psi

Thanks Vohk, I'm kinda surprised it's that tight an aspect ratio. How's the spool? I would expect that to be a very responsive setup

Radski30 said:

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

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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]

the only reason he mad it up is the perfect spring snow conditions a really good running stock sled with a pretty good rider could make it up with out to much strain in the condition that day

that race looked like the tortise and the hare.....same results lol

Sad part is the boost on the pumperM8 was turned way down. Think it registered 6.8 on that climb. He gave the Dragon at least a 5 second head start.

So I do not own a Turbo M8 but I do own a 08 PG turbo Dragon 800. I went to Wolf Creek Pass(10500 feet) this weekend three days in a row for my first ride and initial tuning.
I had never been on a turbo sled so I had nothing to base my opinions on. Running 6 lbs of boost for now (will be going to 10.5-11) the seat of the pants dyno was amazing. Like I said I was by myself first two days so I had nothing to compare it to. On day three my friends finally showed up.............
Four sleds to compare to
1. 2005 Summit X 800 with can and DJ clutch kit
2. 2007 AC m1000 with can and clutching
3. 2008 Dragon 800 with a can (identical to my sled other than turbo)
4. 2007 Summit 800 all stock

This was the moment I had been waiting for, real world comparison.
Results were amazing to say the least. It isn't even close. My turbo D8 on 6.5lbs of boost absolutely ruled the others. The 05 summit with DJ clutch kit was the closest in a drag just because it launches so well. After 100 feet I would pull away very very easily. When comparing it to the stock D8 it was just hilarious. I could toy with it on and off the throttle. And this is only at 6.5 lbs of boost and only pulling 7900 rpms. When this thing is turned up to 10 it will be a joke to run against a stocker

So, All of the above taken into consideration. If you can afford it....Turbo it. These are my real world observations from this weekend. I don't have any hard dyno numbers but I do have real world results now. Seat of the pants it aint close, TURBO power is just that bad a$$

Using Density Altitude & Atmospheric Pressure for HP Calc

I'm no physics major, but density altitude calculators are commonly used for aircraft flight calculations, so why not apply it to charge temp. A difference of 60 degrees F (150 vs 210) at sea level (since we're using boost) gives about 3300 feet difference in elevation (air density). I crunched the numbers again at -10,000 feet (below sea level) to better represent running 9lbs of boost at 10,000 feet (based on PSI approximation) and came up with about 3000 feet difference, so it appears to be in the ballpark even when changing elevation dramatically.

I used 29.8 mmhg for altimeter. Dew point didn't seem to have much effect, but I used 50. LINK to a Density Altitude Calculator.

M8T at 10K feet running 9lbs boost. Atmospheric pressure table says 4.6 lbs to bring it bring it back up to sea level HP of 140. Let's use 5lbs to account for a little loss, so you're effectively running the equivalent of 4lbs boost at sea level.
Lets say the 140 stock HP was obtained at 60 degrees F.
At 10,000 feet the stock m8 would make about 98 HP at 60F (or 108 HP at 20 F if you prefer a cold day on the mountain).
4 / 14.7 = 27.2% more air (& 178 HP) if charge temp was 60 F... BUT

charge temp of 110F increases altitude by 3000 feet or 1.6 lbs less PSI
= only 2.4 lbs boost above sea level so about 162 hp.

charge temp of 150F increases altitude by 5300 feet or 2.6 lbs less PSI
= only 1.4 lbs boost above sea level so about 154 hp.

charge temp of 220F increases altitude by 8800 feet or 4.0 lbs less PSI
= effectively sea level horsepower of 140, which is still a huge HP gain.
Atmospheric Pressure Vs. Altitude Table
I know there are more losses to be considered and this is a VERY crude estimation, but it seems to be in the ballpark.
I saw post intercooler (with electric fan) charge temps at 9 lbs that ranged from 90F to 137F last week on Thanksgiving depending on how long of a pull.
Air temp was 35-40 degrees. I love my RG M8T after just one trip & am quite pleased with it at 9 lbs despite the fact that I'm only around 160 for actual HP. It's a HUGE improvement over my m1000 that had pipe, porting, head & nitrous. Easily a 10mph track speed gain.

200HP at 9000ft on 7lbs of boost. Just like it says in the sales brochure.....


You doubt it? LOL.....................

Seat of the pants HP works best for me, and at only 9 lbs my shoulders are sore enough. My buddies with their N/A sleds are all whining that i need to start riding with other guys . If this thing holds together for a year there will be 4 more in our group.

brendan ross said:

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.

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the only reason he mad it up is the perfect spring snow conditions a really good running stock sled with a pretty good rider could make it up with out to much strain in the condition that day[/QUOTE]


If I dont remember wrong the hill was much cleaner without all the holes when the XP ride, the stock Rev had a extreme 3"x174" track...And we all know about how the "tanks" handling is...LOL

it was impresive to see the stock rev make it.

Don't go foolin yourself thinking a stock rev can outclimb a turbo nitro though. I would like to of seen that rev try to be the first one up. It wasn't that the turbo sleds could not make it. it was that they were getting tosed around in the ruts from every one else and couldn't keep it pointed where they wanted to make it. Remember the turbo nitro I think it was that jumped over the last 30' or so of the incline. Do you think a stock rev could do that?

SNOMAN1174 said:

So I do not own a Turbo M8 but I do own a 08 PG turbo Dragon 800. I went to Wolf Creek Pass(10500 feet) this weekend three days in a row for my first ride and initial tuning.
I had never been on a turbo sled so I had nothing to base my opinions on. Running 6 lbs of boost for now (will be going to 10.5-11) the seat of the pants dyno was amazing. Like I said I was by myself first two days so I had nothing to compare it to. On day three my friends finally showed up.............
Four sleds to compare to
1. 2005 Summit X 800 with can and DJ clutch kit
2. 2007 AC m1000 with can and clutching
3. 2008 Dragon 800 with a can (identical to my sled other than turbo)
4. 2007 Summit 800 all stock

This was the moment I had been waiting for, real world comparison.
Results were amazing to say the least. It isn't even close. My turbo D8 on 6.5lbs of boost absolutely ruled the others. The 05 summit with DJ clutch kit was the closest in a drag just because it launches so well. After 100 feet I would pull away very very easily. When comparing it to the stock D8 it was just hilarious. I could toy with it on and off the throttle. And this is only at 6.5 lbs of boost and only pulling 7900 rpms. When this thing is turned up to 10 it will be a joke to run against a stocker

So, All of the above taken into consideration. If you can afford it....Turbo it. These are my real world observations from this weekend. I don't have any hard dyno numbers but I do have real world results now. Seat of the pants it aint close, TURBO power is just that bad a$$

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Not to pick on you, but you're comparing a sled with over $6 into it against some stock sleds, what's even worth comparing?

The comparison, if any of us are making it, would be dollar for dollar. $6k worth of N/a mods vs $6k worth of turbo. The results get kind muddy then.

Also, if it's a PG D8, can you turn it up to 10? (assuming you add some race gas of course, but can that be done?)