Not gaining speed/rpm

What would cause lap times/RPM to stay identical between qualifying and the race yet the tires were way too soft for qualifying and significantly harder for the race? We kept the gear the same between qualifying and the race. We aren't as concerned about the lap time as we are about the RPM staying the same. We thought we'd pick up at least 100 maybe 200 RPM by going with harder tires. In the race my son had the fastest lap time and our tires seemed right but he only turned 5600 RPM in green plate. We try to get around 5700-5800 at this track because of the tight turns and RPM drops.
 

Bumpy

Member
"We aren't as concerned about the lap time as we are about the RPM staying the same."
Your RPMs are not what wins the race, it's the lap times.
I would say your gearing is off, since tires made no difference in lap times.
At 5600 and fastest lap time, did you win the race ?
 

flattop1

Dawg 89
Typically when i made changes and RPM did not change the chassis was tight .
 

95 shaw

Premium User
Did track change between qualifying and feature?

My guess is that the track changed enough to nullify the difference in tires.
if you have a mychron 5, overlay the speeds, vs rpm on both times on the track. you may see where the differences are.
 
Did track change between qualifying and feature?

My guess is that the track changed enough to nullify the difference in tires.
if you have a mychron 5, overlay the speeds, vs rpm on both times on the track. you may see where the differences are.
This is exactly what we were just talking about. The track was very hard after qualifying and I think our tires were still too soft.
 
So where did you finish ?
He finished 2nd after leading and trying to split a lapped kart with the kid behind him with only 2 laps to go. Lapped kart moved up in front of my son. We were running almost the same lap times as the kid that won, my son would be faster one lap and then he'd be faster, but based on the times of the other classes we think there was probably .2 we were missing.
 
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Green plate on our deal is done at 5500. We had one motor that wouldn't pull past 4800 on the kart, adjusted valves and coil gap and it would pull up to 5300 then, some of the plate cams just don't like RPM. Have you run the kart down the street to see what its capable of turning on the kart? That motor I just described pulled fine on the dyno to 57-5800 but on kart wouldn't.
 
Green plate on our deal is done at 5500. We had one motor that wouldn't pull past 4800 on the kart, adjusted valves and coil gap and it would pull up to 5300 then, some of the plate cams just don't like RPM. Have you run the kart down the street to see what its capable of turning on the kart? That motor I just described pulled fine on the dyno to 57-5800 but on kart wouldn't.
We've had no problem getting it to 5700-5800 at this track. I think we've even had it at 5900 (not intentionally.)
 

alvin l nunley

Premium User
Did the rollout on the tires change any? It could be that you were actually going faster with the high-pressure tires, but at the same RPM.
 
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