How do you figure out what RPM you should be aiming for at a given track

Ratistiss

Member
At our home track we aim for 5800 rpm's but recently we were at another track where it was suggested to aim for 5200. The tracks were very different in length and banking. which made me think what data do I track to figure out what i need at a given track for rpm's so I can be in the best gear.
 

CarlsonMotorsports

Site Supporter
Consider rpm drops more than peak. I know, we all refer to peak rpm with engines in oval karting, but your drop rpm and power curves are what determines the peak rpm you are aiming for. Your engine builder is simply offering you a peak target to aim for.

Big momentum tracks have lower rpm drops, therefor you will need to over-rev the peak of your HP curve less.
Tighter tracks with higher rpm drops require turning the engine more rpm to keep the engine in the meat of it's powerband at corner exit.

Keep in mind that dynos cannot simulate track conditions or rpm scrub.

Short answer = a stop watch never lies.
If it's faster on your mychron, then it's faster on the track.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
33 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 

racing promotor

Moderator
The specs and details of your engine and what the builders dyno tells him dictate your target RPM’S, not which track. Now you change your target RPM’S some based on certain track characteristics and configuration based on experience racing there, which engine and plate color are you using that you normally target 5800 rpm, what was the logic behind someone telling you only target 5200 rpm for the other track,
Was that for the same engine ?
 

Ratistiss

Member
Consider rpm drops more than peak. I know, we all refer to peak rpm with engines in oval karting, but your drop rpm and power curves are what determines the peak rpm you are aiming for. Your engine builder is simply offering you a peak target to aim for.

Big momentum tracks have lower rpm drops, therefor you will need to over-rev the peak of your HP curve less.
Tighter tracks with higher rpm drops require turning the engine more rpm to keep the engine in the meat of it's powerband at corner exit.

Keep in mind that dynos cannot simulate track conditions or rpm scrub.

Short answer = a stop watch never lies.
If it's faster on your mychron, then it's faster on the track.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
33 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
Thanks Bryan, this is the best explanation I have seen about rpms and gives a me a better understanding of what I am trying for.
 

Ratistiss

Member
The specs and details of your engine and what the builders dyno tells him dictate your target RPM’S, not which track. Now you change your target RPM’S some based on certain track characteristics and configuration based on experience racing there, which engine and plate color are you using that you normally target 5800 rpm, what was the logic behind someone telling you only target 5200 rpm for the other track,
Was that for the same engine
My engine builder has us targeting 5800 rpms on a blue plate Jr.sportsman champ kart. I am new to this so I cannot say I understood why it was recommended, but we plan on running different tracks this year and it is important to me to understand how to get in the right gear range.
 

"J'-remy

Member
target rpm is a good place to start. lap times and rpm drop will tell you the rest. be prepared to experiment. Tracks that are full throttle vs trail breaking or burp and roll out will be different targets. again trying different things is essential.
 

racing promotor

Moderator
My engine builder has us targeting 5800 rpms on a blue plate Jr.sportsman champ kart. I am new to this so I cannot say I understood why it was recommended, but we plan on running different tracks this year and it is important to me to understand how to get in the right gear range.
Blue plate clone ? Animal ? Flathead ? Predator ? Did he say target 5800 MAX rpm for sure ? I ask because if so that's low for any blue plate, unless maybe a slight predator built.
 

racing promotor

Moderator
Sorry, Blue Plate Animal
I'd be questioning why only 5800 rpm that's really low for Max RPM. If your new I assume the driver is as well, once you confirm the 5800 is max rpm to start out you'll be best suited to just target max rpm every where, or you'll have yourself all screwed up and be out to lunch. For a blue plate animal 6200 max rpm would be much closer even that is lower than most, even if 5800 was perfect for a certain track, there would be NO circumstances where you would only turn 5200 max somewhere else. Remember there's a lot more to making rpms than just gearing, with momentum being at the top of the list, and lots of things come into play to maximize momentum, seat time, track size and shape, amount of grip available, right tires to match that grip available with right air pressures, I can go on and on don't let that get you discouraged it's not rocket science either, just be aware of all the details just chasing gearing will screw ya up also.
Of course ask questions and learn all you can learn, but trust me for now confirm MAX
RPMS and just target that everywhere, as it help you get where you need to be quicker without wasting weeks of racing. Ask for proven starting gearing combo that you know is good info for each track and go with it.
Good luck. !!
 
Don’t worry about peak rpms….. or how much your motor builder tells you to turn the motor. Find out where the max hp is on the dyno and shoot for that when coming out the corner….. adjust your gearing to compensate if you need more or less. Especially if you are off the throttle.

A lot of the top guys are not worried about what the motor actually turned for max rpms. They are looking at the rpm once off the corner. Why wouldn’t you want your peak hp at the moment you are at the start of a straightaway…… the part of the track where you create your speed…..

Message me if interested on why…..
 

racing promotor

Moderator
If you get gearing info make sure your comparing apples to apples, blue plate animal on a flat kart is different than your sportsman champ will be, you'll need either more rear gear or one size smaller front driver than they would use.
 

CarlsonMotorsports

Site Supporter
Depending on the difference in drop rpm between the two tracks, it's not out of the ordinary to suggest turning 500 less rpm at a big momentum track verses one that puts the engine in a bind an drops 1500 rpm.
Another thing to consider is that blue plate (any small restrictor plate) racing is all about momentum, and rarely will a blue plate drive lift out of the throttle (even on tight cornered tracks.) Open up the corners, arc them with a late entry and late exit with apex just after the center of the corner to keep your momentum up. That will help on limiting drops.


Question for all: How do you think that engine builders come up with a peak "target" rpm?
I know how I and several others do it, but it would appear by some replies on this thread that there are other methods being used to determine peak target rpm for the track based on data from the dyno.
 

"J'-remy

Member
I would hope they determine that HP peak is at the apex of the corner and the engine would almost be out of breath (target RPM) at entry into next corner at end of the strait. you want you engine to be in the upward curve as long as possible before it crests the hump and looses power. this i why i usually get my engines dynoed i wish my builders would just give me a print out
 

paulkish

old fart
If your engine makes power to 5800 and you using it to 5200, your not bringing everything to the racing table.
 
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