Traction Vs Boost and Clutch Set Up

[REDLINE 1]

Great pic ! Is that on the west or east side of the Tetons?

 

[AAdavis]

Great pic ! Is that on the west or east side of the Tetons?

East

 

[KnappAttack]

Well after mother nature pumped 60 inches of snow in a week at the Tetons the sun came out and I got a ride in and did some data logging. The snow was soft and loose. I was digging 3 to 4 inches deep into the trail any time the throttle was wide open up to 90mph. The boost would run from 14.5 up to 16psi, the high number coming in between 80 and 90 mph. The rpm was between 8200 to 8500rpm. A/F ratio was 11/1.The logs were taken at 9000ft. On the same trail with better traction I was tagging the rev limit. I would guess the boost on that day 17 to 18psi. I suspect I have less traction than anyone. I am at a higher elevation than anyone else running trails. If someone has a data log on a trial at this elevation I would love to see it! I have no doubt that traction does affect boost and clutch tuning. I also believe that altitude affects boost. Having said all that I am satisfied with how it runs and the set up of the track for what I like to ride.

Traction is going to affect the clutching for certain, but it shouldn't affect the boost.

Here at about 1000 foot above sea level, the boost is there for me whether spinning in the deep powder or hooked to the max, I use a 1.25" Rip2 however. RPM will spin the turbo wether hooked or not. Getting the clutching right will keep your RPM in the proper range and prevent hitting the limiter. It sounds like you need to change the helix and spring setting in the secondary clutch to get better consistency from spinning too hooked. I also think a deeper lugged track than the 1" would suit your needs better, at least a 1.25 or 1.5" track. What at the specifics on the secondary and primary?

That boost sounds very low for altitude at 14.5 climbing to 16, and isn't making much for power. If I had to guess you are at less than 240 HP at that 9000 foot mark. Boost shouldn't be climbing a pound and a half like that. Something seems really off on this machine for things to be all over the place. You should be logging this machine every time the key goes on if you want to get answers and not guess on things Art. Something just isn't kosher with this thing. We need to know your clutch setup because it's really off. I suspect some boost leaks as well.

 

[AAdavis]

Traction is going to affect the clutching for certain, but it shouldn't affect the boost.

Here at about 1000 foot above sea level, the boost is there for me whether spinning in the deep powder or hooked to the max, I use a 1.25" Rip2 however. RPM will spin the turbo wether hooked or not. Getting the clutching right will keep your RPM in the proper range and prevent hitting the limiter. It sounds like you need to change the helix and spring setting in the secondary clutch to get better consistency from spinning too hooked. I also think a deeper lugged track than the 1" would suit your needs better, at least a 1.25 or 1.5" track. What at the specifics on the secondary and primary?

That boost sounds very low for altitude at 14.5 climbing to 16, and isn't making much for power. If I had to guess you are at less than 240 HP at that 9000 foot mark. Boost shouldn't be climbing a pound and a half like that. Something seems really off on this machine for things to be all over the place. You should be logging this machine every time the key goes on if you want to get answers and not guess on things Art. Something just isn't kosher with this thing. We need to know your clutch setup because it's really off. I suspect some boost leaks as well.

The clutching is stock other than the primary arms. Yes a different track could give more grip but I do not want that. To get the clutching right I would have to change the set up by the days snow condition. It can vary quite a bit here day to day. At this point I am satisfied at 15 to 16 boost. I think its a very safe level to run and its all the power I can use. MC Express says 240hp is all there is in a stock turbo. Claims beyond that are bogus.

 

[Fords4life]

The clutching is stock other than the primary arms. Yes a different track could give more grip but I do not want that. To get the clutching right I would have to change the set up by the days snow condition. It can vary quite a bit here day to day. At this point I am satisfied at 15 to 16 boost. I think its a very safe level to run and its all the power I can use. MC Express says 240hp is all there is in a stock turbo. Claims beyond that are bogus.

Dont know about 240hp as max hp with stock turbo, was just out in your neck of the woods last week (west of dubois wy) 8100 feet to 9800 feet of elevation unloaded @ 240 hp hurricane high elevation tune and was turning 8650 rpm consistently switched her up to 270hp high elevation and rpms were bang on 8950rpm....turbo maxed @ 240hp???? dont think so!!

 

[Doc Harley]

Dont know about 240hp as max hp with stock turbo, was just out in your neck of the woods last week (west of dubois wy) 8100 feet to 9800 feet of elevation unloaded @ 240 hp hurricane high elevation tune and was turning 8650 rpm consistently switched her up to 270hp high elevation and rpms were bang on 8950rpm....turbo maxed @ 240hp???? dont think so!!

I think the comment "turbo is maxed out @ 240hp." Is a loaded response. Especially at 10,000ft and holding the flipper to the bar endlessly.
I believe it to being closer to the truth than the number 300hp, from an efficiency standpoint.

 

[Simplespeed]

240, 250, 260, 270 it really don’t matter if you get the power to the ground … Fact is its plenty of power and when it is applied efficiently its more than enough.. Dyno’s have always varied from one to another as some of us are real world guys, and some are selling products and live in the dream world … Different strokes for different folks… And my last comment is Yamaha selected the stock Turbo size for efficiency and lack of Lag not maximum horsepower from my understanding…

 

[earthling]

Piggyback EFI controller vs ECU flash. The ECU has far more information and much finer grained control over engine parameters.

 

[KnappAttack]

The clutching is stock other than the primary arms. Yes a different track could give more grip but I do not want that. To get the clutching right I would have to change the set up by the days snow condition. It can vary quite a bit here day to day. At this point I am satisfied at 15 to 16 boost. I think its a very safe level to run and its all the power I can use. MC Express says 240hp is all there is in a stock turbo. Claims beyond that are bogus.

MCX is out to lunch saying that, but of course altitude is going to lower the output. The Pro-Mods are up over 400HP using that turbo at mid 30's for boost, Trail sleds are getting around 300 at around 17.5-18 lbs. of boost with a header tune, of course its going to take more boost to get the same power at higher altitudes.


So you are using a stock secondary setup? There's the problem. You need something more like a straight 35 helix and say a Dalton Black/Orange setup at 80-90 wrap for the conditions you are running in. That stock 35-39 reverse helix is total garbage. It over revs bigtime down low and under revs up top. I've found in loose snow and spinning a straight 35 to be best all around to keep RPM consistent and keep RPM up. On hard packed trails, I run a 41-37 with the same B/O set on 90. Straight helix on hardpack the sled just slows a bit, the progressive helix is faster, but your running a bare un-studded 1" track I think anyways, so it's never going to hookup up well, its always spinning. Go to a straight 35 Dalton B/O at 80 or 90 and don't look back, tune the primary and RPM to this secondary setup. Shoot for around 9000 RPM and be done if thats all the boost you have and are running.

Take the reverse angle 35-39 and toss it in the garbage because it doesn't work in any conditions, unless you have an extremely weak tune on the bottom end. I can't stress this enough. Even the stock sled over revs on the bottom with it and under revs up top with that piece of crap reverse helix. It's total garbage, only good for a paperweight is all, you will never get good consistency from it in the snow or the trail... Stock sled hits 9300 on the bottom and drags down to around 8500 with it. Tuned sled is even worse over rev down low.

 

[AAdavis]

Dont know about 240hp as max hp with stock turbo, was just out in your neck of the woods last week (west of dubois wy) 8100 feet to 9800 feet of elevation unloaded @ 240 hp hurricane high elevation tune and was turning 8650 rpm consistently switched her up to 270hp high elevation and rpms were bang on 8950rpm....turbo maxed @ 240hp???? dont think so!!

Two questions. Do you have a header? Do you have a boost gauge or data logging? I want to know what your boost levels were at 9800ft? As I understand it the header tune runs less boost. It snowed a lot last week did yours ever hook up? The fact that the 270 tunes runs more rpm syncs with mine making more boost when I have more traction.

 

[KnappAttack]

Again, traction or lack of traction, is not going to affect the boost levels if you are WFO throttle. It's going to boost the same every time you are WFO wether hooked up solid or not. The RPM will change from the clutching however.

A header will make the same power as stock manifold, but at a couple less lbs of boost. for comparison.

 

[Fords4life]

No header, my sled is clutched for my 5500 to 6800 feet of elevation @ 240 hp so going higher in elevation is what i have the 270hp for a correction factor, yes at times my sled was hooking good dependent on snow how packed trails were friday or saturday, no idea of boost didnt care it was working well, 1.25 inch x129 inch ripsaw 2 with 3 studs per bar 5/8" penatration. Have a 39/35 degree ulmer helix NOT reverse with epi purple spring @ 6&3 was @ 9&1 as per alans sugestion, primary is apex with thunder orange spring with heavy hitters set to my testing specs which i can give you if you like, stock gearing @ 21/41.

 

[AAdavis]

No header, my sled is clutched for my 5500 to 6800 feet of elevation @ 240 hp so going higher in elevation is what i have the 270hp for a correction factor, yes at times my sled was hooking good dependent on snow how packed trails were friday or saturday, no idea of boost didnt care it was working well, 1.25 inch x129 inch ripsaw 2 with 3 studs per bar 5/8" penatration. Have a 39/35 degree ulmer helix NOT reverse with epi purple spring @ 6&3 was @ 9&1 as per alans sugestion, primary is apex with thunder orange spring with heavy hitters set to my testing specs which i can give you if you like, stock gearing @ 21/41.O

Again, traction or lack of traction, is not going to affect the boost levels if you are WFO throttle. It's going to boost the same every time you are WFO wether hooked up solid or not. The RPM will change from the clutching however.

A header will make the same power as stock manifold, but at a couple less lbs of boost. for comparison.

So Hurricanes off the shelf Hi Elev tune with header would have a couple less lbs of boost at the 270hp level vs the stock header tune?

MCX is out to lunch saying that, but of course altitude is going to lower the output. The Pro-Mods are up over 400HP using that turbo at mid 30's for boost, Trail sleds are getting around 300 at around 17.5-18 lbs. of boost with a header tune, of course its going to take more boost to get the same power at higher altitudes.


So you are using a stock secondary setup? There's the problem. You need something more like a straight 35 helix and say a Dalton Black/Orange setup at 80-90 wrap for the conditions you are running in. That stock 35-39 reverse helix is total garbage. It over revs bigtime down low and under revs up top. I've found in loose snow and spinning a straight 35 to be best all around to keep RPM consistent and keep RPM up. On hard packed trails, I run a 41-37 with the same B/O set on 90. Straight helix on hardpack the sled just slows a bit, the progressive helix is faster, but your running a bare un-studded 1" track I think anyways, so it's never going to hookup up well, its always spinning. Go to a straight 35 Dalton B/O at 80 or 90 and don't look back, tune the primary and RPM to this secondary setup. Shoot for around 9000 RPM and be done if thats all the boost you have and are running.

Take the reverse angle 35-39 and toss it in the garbage because it doesn't work in any conditions, unless you have an extremely weak tune on the bottom end. I can't stress this enough. Even the stock sled over revs on the bottom with it and under revs up top with that piece of crap reverse helix. It's total garbage, only good for a paperweight is all, you will never get good consistency from it in the snow or the trail... Stock sled hits 9300 on the bottom and drags down to around 8500 with it. Tuned sled is even worse over rev down low.So I have the admit than this is the first snowmobile

I have to tell you this is the first snowmobile I have owned. So I have no clue what your telling me about the secondary. I understand the primary. I do not have a bare track. I am running about 12 ice screws per row. So tell me what it is I need to buy to set up the secondary?

 

[AAdavis]

Ok, so I just read a low boost thread. A sled that had no detectable leaks runs 17psi on a 270 hp tune at sea level. no mention of a header. So my sled at16psi with header at 10k ft I think is running correctly.

 

[KnappAttack]

So Hurricanes off the shelf Hi Elev tune with header would have a couple less lbs of boost at the 270hp level vs the stock header tune?

I have to tell you this is the first snowmobile I have owned. So I have no clue what your telling me about the secondary. I understand the primary. I do not have a bare track. I am running about 12 ice screws per row. So tell me what it is I need to buy to set up the secondary?

35 helix from Dalton and a Black/Orange Dalton secondary spring, I'd set the spring at 80 or 90 wrap. Which is 2 & 6 = 80 degree wrap, or 3 & 6 = 90 degree wrap, just add the two numbers and thats what we talk about wrap. If you are using stock secondary rollers I'd start with the 80 wrap, just know that wrapped up higher will backshift quicker and make more RPM. It would/could also make more clutch and belt heat and blow a belt. The key is to only pinch the belt as much as you have to without slippage. I run the wrap up at 90, but I also use Hi-Torque rollers that roll easier and show less side pressure on the secondary on the scale than the stock sticky rollers that don't roll well or easily.