Some fun testing - motec sidewinder

[Brent68]

Its been 9 days, any more ride updates?

This weekend was more dedicated to riding than tuning. Clutching is still not the way I'd like it. I feel like I'm chasing my tail, I have tried about every helix/spring combination available. I over shift from spinning off the line on hard pack (rpm just below the rev limiter at 9400) when it hooks rpm's dip to 8400-8500. Before settling in at 9K it will fluctuate up and down until finally stabilizing after about 4 seconds at 9K. Maybe I just need more traction to prevent the initial over shift or a different primary? The current clutching is DTYA-3 at 91 grams, black/blue primary, 45/33 helix with black/orange at 6-1. The log file shows the RPM fluctuating. BTW this run was from 40 to 120 against the motec doo. It was set to 26 PSI on 110 octane, at least he made me feel good by backing off some so I could stay next him.

No blown belts since initial tuning 600 miles ago. I did get a chance to run a well setup winder (SRX). I was told it was on pump gas at 20 psi. We ran from a dead stop twice and both times we ran side-by-side until 105 mph then I pulled a bit on top. We didn't mark off distance but it would have been close in 660. Running against this sled and seeing the acceleration/top speed, with the short lug track convinced me buy a SRX. I was able to find one at Port Washington Yamaha.....It will be next year's project sled.

• Installed an Earth X lithium batter and worked very good in -10F this past weekend.
• Added the Tommcat constant tension charge tube clamps (very nice clamps).
• Put rings on ski's to hold ice scratchers to avoid unwanted deploy (saw this on another post).

 

[KnappAttack]

I'd like to see you try a Dalton White Cat or Black/Lime torsion spring. I'm of the opinion that the Black/Orange is just not enough spring for this big power. You also may like going to the 8DN belts as well. I ran a heavier driven spring last week with great success, and the 8DN made things much more consistent as well. This would help with your overshifting down low too. The Dalton Cat white is equal to a Cat sno-pro green.

Set the Cat torsions at 9-1 or 0-1 as a starting point.

I was never happy with the Black/Orange for the trail and the lack of top end with it. IMO not enough side pressure to prevent driven belt slippage. Seems fine up to 240-250 real HP, beyond that I don't think its enough spring myself. May be fine for ice or hadpack, snow and hard pulling not enough pressure to stay hooked on the belt.

 

[sledding rocks]

I tried the 35/39 , 41/35 , 41/37 , with the black /orange spring , I was seeing the same rpm situation u r seeing on a tuned 300hp srx . im now currently back to a straight 35 with the new black / tan spring at 50 degrees , much better rpm pull 9100 rpm and settle at 8900-9000 rpm , xs 825 belt , zero belt dust , clutches cool/warm ,

 

[Brent68]

I'd like to see you try a Dalton White Cat or Black/Lime torsion spring. I'm of the opinion that the Black/Orange is just not enough spring for this big power. You also may like going to the 8DN belts as well. I ran a heavier driven spring last week with great success, and the 8DN made things much more consistent as well. This would help with your overshifting down low as too. The Dalton Cat white is equal to a Cat sno-pro green.

Set the Cat torsions at 9-1 or 0-1 as a starting point.

I was never happy with the Black/Orange for the trail and the lack of top end with it. IMO not enough side pressure to prevent driven belt slippage. Seems fine up to 240-250 real HP, beyond that I don't think its enough spring myself. May be fine for ice or hadpack, snow and hard pulling not enough pressure to stay hooked on the belt.

Thanks for the advice, I ordered Dalton's Cat White spring! I will try it next weekend and report how it works out. What do you think about the helix (45/33) and primary spring (dalton blue)? Thanks again!

 

[Brent68]

I tried the 35/39 , 41/35 , 41/37 , with the black /orange spring , I was seeing the same rpm situation u r seeing on a tuned 300hp srx . im now currently back to a straight 35 with the new black / tan spring at 50 degrees , much better rpm pull 9100 rpm and settle at 8900-9000 rpm , xs 825 belt , zero belt dust , clutches cool/warm ,

Thanks for the response! I will try this option after trying Mr. Knapp's idea. I bet your SRX runs great with a 300hp tune.

 

[KnappAttack]

Thanks for the advice, I ordered Dalton's Cat White spring! I will try it next weekend and report how it works out. What do you think about the helix (45/33) and primary spring (dalton blue)? Thanks again!

I run the Dalton Black/Blue in mine also. I started with the 41-37 with the EPI purple set at 0-1 (equal to the Dalton white at 9-1) and ended up back with the 35 as the RPM's were too low using the 41-37 early in the run, the R's would climb down track as it got into the 37 range, the 35 was the only strait angle helix I had so it went back in. May have been better with my 39-35 but went right to the 35. straight 37 or 38 may work better. The Dalton weights seem to like straight angle helix's like ClutchMaster has been saying.

When running the Dalton Black/Orange in the driven last season, I never had RPM's too low initially and climbing down tack when running progressive helix's, only thing I can think is when I was running that spring, I was slipping in the driven all the time with it, the more power I made, the worse it slipped. I couldn't even tell when I switched and clicked up tunes, now with the heavier secondary spring I sure can when I click up to the next tune! Never been a heavy spring guy, but I am now after seeing the results. Guess we need them on the big tunes.

I also noticed the excellent consistency of the 8DN! Just had a fella PM me about the inconsistency of the 8JP with fluctuating RPM's, and I forgot about how inconsistent the 8JP was for me after running the 8DN. The 8DN ran the same time after time for me last week. If this Team setup isn't all that and a bag of chips, I know what I'm going back to straight on with Yamaha primary, the 8DN.

 

[sledding rocks]

Thanks for the response! I will try this option after trying Mr. Knapp's idea. I bet your SRX runs great with a 300hp tune.[/QUOTe
yes it does

 

[ClutchMaster]

I agree that you really need a heavier secondary spring especially with that much power. Going to a heavier spring will allow you to take that huge split angle helix down some. Running something a bit straighter like a 45/38. I guess you’ll have to see how the white spring works then you can determine where you need to go.
STM has a HUGE orange spring, I’m thinking of trying it out....it’s been laying around the shop stalking me.

 

[ClutchMaster]

Your overshifting from track spin....well that’s a traction problem, it’s just gonna happen, not much you can really do except improve traction.
The stiffer spring might resist that somewhat but it will just smack the limiter. It may not drop as much tho when you regain traction.

 

[boostfever]

Another option if you dont want to go crazy with studs is to delay max boost for a small period of time. This can be set up easily in the motec. I have spent hrs looking at data logs that show what you are describing.
Using the race time function you can reduce max boost. For example you could hold boost at 17lbs for .8 seconds, have it set to 20-21 at 1.3 seconds, the motec will seamlessly ramp up the boost smoothly to help control track spin and rpm overshoot.
Race time is only active above 95% throttle typically

** I was looking again at your data log... looks like you already have the boost controller set up with a slight delay

 

[Brent68]

Another option if you dont want to go crazy with studs is to delay max boost for a small period of time. This can be set up easily in the motec. I have spent hrs looking at data logs that show what you are describing.
Using the race time function you can reduce max boost. For example you could hold boost at 17lbs for .8 seconds, have it set to 20-21 at 1.3 seconds, the motec will seamlessly ramp up the boost smoothly to help control track spin and rpm overshoot.
Race time is only active above 95% throttle typically

** I was looking again at your data log... looks like you already have the boost controller set up with a slight delay

You’re correct, I do have the race time functions active for lambda, boost, and timing. I was using the boost function to hit the aim boost accurately on initial spool. I didn’t think about using it to help with clutching, I’m going to do some testing. Thanks.

 

[boostfever]

Have you watched to motec webinar about pid.
These are the three parameters the motec uses for boost control.
Another thing to look at that had a major effect on initial overboost is the margin setting, margin determins when the boost controller becomes active. If margin is set to close to aim it will cause a boost overshoot because the motec is late to the game and boost is already ramping up quicker than it can calculate where it needs to be.
Pid requires very small adjustments to the values. Fun stuff dialing these in

 

[ClutchMaster]

Have you watched to motec webinar about pid.
These are the three parameters the motec uses for boost control.
Another thing to look at that had a major effect on initial overboost is the margin setting, margin determins when the boost controller becomes active. If margin is set to close to aim it will cause a boost overshoot because the motec is late to the game and boost is already ramping up quicker than it can calculate where it needs to be.
Pid requires very small adjustments to the values. Fun stuff dialing these in

Don’t you have Base wastegate duty cycle table? Based on 0 ~ 100% duty cycle?
Actually the computer is super fast at making calculations, it calculates injector pulse width for every revolution of the motor. it’s the fact that the diaphragm for the wastegate needs time to bleed off pressure to control boost.
I’ve always had good luck turning off the automatic boost control, adjusting the duty table to get the boost where you want it , then turning back on the automatic control. From there it will subtract or add duty cycle as needed to maintain boost.

 

[boostfever]

There is an aim duty cycle for the boost controller. It can be adjusted easily, but pid is what controls the closed loop boost control,
If pid is a little off it cause boost to fluctuate for a short period of time.
As you stated the diaphram has a reaction time, also the acceleration and inertia of turbine wheels are also factors.
In the case of a trail sled with limited traction and big power, overboost on the hit needs to be avoided before you have any prayer dialing in the clutching. At least based on my own experience....these data logs can drive a man crazy

 

[ClutchMaster]

Yes that the base table, yea all I’m sayin is turn off the closed loop control, tune that table for boost, then turn on the PID control.
You should be able to get good boost control without closed loop, then turn on the closed loop PID after its close.
Trying to tune boost in closed loop will have you chasing your tail.