Clutch Engagement

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My son runs lo206 JR, yelllow slide. According to B&S, peak power (not HP or torque) is between 4000-6000rpm. Like most of our class, we run a stinger clutch with orange springs that engage the clutch at 3200rpm. I'm wondering why folks dont run springs that engage closer to the 4000rpm range. I understand there is a trade off between having the kart engage the clutch early and make progress down the track (albeit at lower power) vs waiting for the engine to rev to 4000 to engage. I would have thought this trade off favors engaging at 4000rpm because, without load, the engine revs to 4000rpm almost instantaneously vs driving an engaged clutch with a load and driving it up to 4000rpm (which takes time to accelerate a kart+driver at lower power). Theory is one thing but I'd like to hear from folks that have tested both springs set-ups back to back. For what its worth, the few folks that I've spoken with claim that the orange spring produces the faster results overall. However, this thread suggests that the clutch should be engaging closer to peak power (rather than engaging earlier): https://4cycle.com/karting/threads/clutch-clarification.98613/. (I understand this depends on track layout, conditions, driving style etc.)
 
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You want your clutch to engage at peak torque, with little regard to peak HP or weight of kart.
I can guarantee you that peak torque on your yellow slide engine is nowhere near 4000 rpm.
Now, with that said, IF your track configuration is such that you have a tight "technical" corner/hairpin that the engine rpm dips very low, you may want to try lowering your clutch engagement rpm so that it stays engaged through that section of the track.
Back to back testing with your kart, your engine, your driver, all variables kept as consistent as possible, is the only way to tell what will be best for your team. I suspect taht orange springs would work best from the information you ahve given. Keep in mind, though, that what works best for one driver, may not be best for yours. Driver smoothness, rpm scrub, and resultant exit rpm,) etc all impact your lap times.
Engagement/disengagement rpms on sprint road courses can be a challenge to get right, but lap times never lie.


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
"According to B&S, peak power (not HP or torque) " this statement does not make sense, you have misunderstood something. Torque is a force applied in a rotational direction. Horse power is a unit of measurement used to determine the amount of force in relation to time. So the only measurements you concern yourself with are tourque and HP The clutch is generally locked up in the area of peak torque. Canyou direct me to the link or document that B&S refers to POWER.
 
Energy cannot be created or destroyed so, where does it go? If you set the engagement at peak horse power you might think this would give you more power for acceleration but, the clutch technology is limited. The clutch will slip much longer as the kart gets up to speed. This produces allot of heat which is energy wasted that does nothing to make the kart go faster. That amount of heat will melt the clutch parts as the only time the clutch would be engaged would be in over wind rpm.

This is why you want the clutch to be locked up as the engine gets to it's maximum twisting force to minimize heat loss and help the clutch work the way it should.

Sundog
 
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During these times when it seems you can't trust any one (or at least certain people) i'd suggest you try different clutch engagements and see if it helps you.
 
Are you a member of Facebook? I have some articles under Mayko Products. One addresses horsepower, you might read that.
 
alvin l nunley said:
Are you a member of Facebook? I have some articles under Mayko Products. One addresses horsepower, you might read that.
Click to expand...

Al, it's a general thing on here that you don't lead readers away from here to Facebook.

Maybe instead you could copy and past on here the help your offering?

If you have help to offer, offer it on here.
 
thanks everyone. That's very helpful. Sundog's point is one that I had not considered but makes perfect sense, the clutch will take longer to engage at higher RPM. I will try it and report back.
 
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