Sprocket Size vs. Performance

And the results are ..........interesting! We'll do another session in two weeks. I don't have all of the times available yet to give precise comparisons but I was more than .2 closer to the fast guy last night. Next race is on an even more of a momentum lay out so I expect good feedback. By the way, all this conversation about jetting on this thread is a diversion at best but for sure a waste of time.
 
Continuing on my first post. We went to the track with the 18/67, after tuning and getting chassis where we wanted, switched to the 16/60 and picked up time. Again, we used the 18 on the big flowing momentum track and tried it on the tighter track we were on this week. Just to clarify, we use different length chain and motor is in same position within 1/4 inch.

Some say ratio is a ratio. Changing driver works for us.
 
Kart43 said:
Strip away, the engineers and professionals from your favorite Nascar, F1, or Indy Car team and see where they stand.
Click to expand...

I don't think any of the above 'just' hire engineers. They higher engineers who are also racers with racing experience.
 
Bob Evans said:
Chain tension.

Apply 10 ft/lbs of torque to the clutch driver and replace a chain link with something that measures weight, then tell me that a 12 tooth driver will give you the same reading as a 16 tooth driver.
Click to expand...

In what follows I'm picturing things looking at the engine, clutch, chain, axle gear and axle from the drivers side.

I read your test to suggest removing links between the clutch driver and the axle. Then replace the removed links with a spring scale. Next hang a 10 pound weight on the chain directly forward of the center of the clutch driver and read what the scale on the chain between the clutch gear and the axle gear tells us, when the axle is locked down and not able to spin. Then do the same with a different driver. I think with different drivers you will get different results.

I remember Al years ago on Pete's site suggesting a different type of test. It's been years and I'm not sure if I'm remembering his test and use of the test correctly. I'm sure he'll correct my errors. ... :)

In Al's test we will test the whole clutch and axle system. Put your kart on a stand and duck tape one end of a string to a rear tire. Then wrap the string around the tire top to the front enough times, so the end of the string if unwound can reach the ground. You then hang a 10 pound weight on the end of the string, wind it up and time how long it takes the weight to hit the ground. Next change to a different like ratio keeping the length of chain the same. Then wind the string up to the same height and time how long it takes for the weight to hit the ground.

Al, will the same weight using different ratios hit the ground at "exactly" the same time from the same height?

Answer: If you don't do the test and only go by calculations, the calculations will tell you the weight will hit the ground at the same time. But if you do the test, because the physical gears have been changed the weight will not hit the ground at "exactly" the same time.

Ok, we use stagger what would happen if instead of changing gears you just switched the test from one rear tire to the other?

Answer: It will work out the same. If you only calculate what the results will be like the engineers on here calculate ratio is a ratio, neglecting physical changes, the time will be the same. But if you actually do the test you will get different answers because when using a staggered solid axle the two rear tires are physically different, even though the axle to clutch ratio remains the same.

maybe because I just winged it using backyard mechanics. ... :)
 
Flash-o-matic said:
And the results are ..........interesting! We'll do another session in two weeks. I don't have all of the times available yet to give precise comparisons but I was more than .2 closer to the fast guy last night. Next race is on an even more of a momentum lay out so I expect good feedback. By the way, all this conversation about jetting on this thread is a diversion at best but for sure a waste of time.
Click to expand...

Some folks seem to write a lot more then is necessary. ... :)

You could have just said "paul was right". ... :)
 
Ok if this is starting to get confusing let's throw in 219 chain and drivers and gears . Less weight less pitch circle on both driver and gear . And some say a ratio is a ratio . Now what's the experts opinions ? '
 
I'll just say this, Anyone that thinks Ratio is Ratio to race dirt oval LTO just does not have enough experience, or unwilling to experiment, but for sure does not spend much time in the payout line when the race and tech is over.
 
S&MRacing said:
16 is going to spool you up faster coming out of the turn, 18 will give you that oompf further on down the straight away. Its part the gearing game of which one will work better, its all how you want the power to come in for your own setup and driving. Seen people gear theres both ways and be fast.
Click to expand...

Interesting. Out of 89 posts, one of the most reasonable and accurate answers occurred on Post #2.
 
Flash go ahead finish your test (Engineering etc ) while I get the idea of one set of standards for a test . I think there are a lot of variables in this equation . We already have dirt vs pavement speed way vs sprint but I don't see a 35 pitch vs a 219 pitch chain etc Ive actually enjoyed reading everyone's ideas. So keep it up it intresting and fun
 
I too have enjoyed reading everyone's input but honestly all I can, or want to test/compare is 35 chain on a sprint kart in an environment I can somewhat control. All of what has been contributed in this thread is valuable info but for the most part we've all read this here through the years. I have an excellent opportunity to observe these changes / effects.
 
After reading all these theories, the only conclusion I've come up with is that I really don't care why, or even if, any of them are correct. On dirt ovals, I have felt the difference on the track, and seen it with my on track performance. Even if it's all in my head (which I also believe can change performance :) ), changing sprockets and drivers is so easy that I'm going to continue to believe "ratio is not ratio" just in case it's true. If it's not true... no harm, right?

I've also recently bought a sprint kart for asphalt road racing, but I don't yet have enough experience with it to tell if there is a difference there or not.
 
Bob's makes ratio discussions fun! There are no units of measure to a ratio, they are nothing, the are just a number that's used as a relation of one thing vs the other. (I often wonder if the Martha Stewart cooking website discusses in depth the relationship of 1 part egg yolk to 2 part whites and the difference it makes in the speed of a cake coming out of the oven?)

There are many dynamic reasons why one gear set reacts differently than another, but sadly it has nothing to do with what the ratio is.
 
racing promotor said:
I'll just say this, Anyone that thinks Ratio is Ratio to race dirt oval LTO just does not have enough experience, or unwilling to experiment, but for sure does not spend much time in the payout line when the race and tech is over.
Click to expand...

Smartest thing I have seen in this whole thread
 
Personly I'm waiting for the Martha Stewart cake . I like the idea of having your own cake and eating it too . But I still would like to see what Flash comes up with . That would be like frosting for the cake . Oops pardon me I forgot I'm on a diet . Lol
 
You must log in or register to reply here.
Back
Top