Ok, there has been a dozen ROLLOUT Threads, but I lost the one I thought I had saved w/ some different rollouts for different size tracks.

Running a ASPHALT Flat Track, foam tires, and about 240 ft. run line...

Seems to me I was looking at about a 2.60 rollout, does that sound close?

Our asphalt track is pretty wide and sweeping with low bite, runline is 268' (I wheeled it the other day) and we rollout a Monster at 2.30-2.40 range.

It seems low but asphalt is tricky. Willow Mill in PA is about the same size as our track just a little tighter and they use a similar rollout.

THE LAST WILLOW MILL RACE i rolled it at 2.48 for a 40 lap run and i was on the pole of the b !!!!

xxxxx wrong thread

Hey Joe,
If this is for Hot Rods I missed TQ in Sportsman stock by 3 seconds on Sun. with a rollout of about 2.51 and I was tempted to take a tooth off. I think I may have even spun once or twice during that run.
Andy

Andy,

How many laps did you end up running? I'm looking for a fast 39 to 40 lapper. (41 would be better..but I'm not greedy)

Hey Im still new so i did a slow 37 lapper, those dots on the inside of the corners gave me hell. Yea tell you the truth the expert stock guys were alot faster down the straight so a 2.60 may work for you Joe if the chassis is right.
See ya Sat.!!!!:)

Joe
Saugus is 232 driveline..As you know fairly tight radius and long straights..Eric has you really close on the rollout estimate..Voltage man!

..Voltage man!

Chassis, Chassis, Chassis, but yeah it helps to have voltage too, once your car is PRIME !! LOL

It guess on rollout my train of thought is alot different than most people's.
The lower I can go due to more RPM the the better.
Trying to roll a motor out high especially in stock is gonna do nothing but heat it up and kill your finishing lap times. If you got the chassis right and the voltage is there, you can still carry the up front times.

...thanks GUYS

I got to put the numbers to a test...pulled out some fresh packs and got the lap times I was looking for. (This was for my sons car...his personal best prior to Saturday were 6.4's and a 37 lap run. He got 38 this time..but more important he was able to run 6.0's and still had a little bit of a push.)

swtour,
how many laps or lap times are the fast stock guys pulling? Sometimes I can help you dial in a better rollout if I know that.

Our track is 268' and we pull 5.6's up front, end on 5.9's if the car is good, 6.0-6.1 if not. A fast run is a Mid 41 lap run.
When the track was freshly paved we could pull 5.4's and end on 5.8-5.9's for a fast 42 lap run.

Erock,

The target was to shoot for 40 laps. I believe the record is 41, but that was at a large event with awesome traction. This weekend 41 did get run at my event as well. (Congrats Larry Ruby)

This is what I ended up with

2.21 Tires
104 Spur
35 Pinion
2.336 rollout

That set up got awful hot, but was the fastest for single lap time, we dropped to a

2.20 Tire (from wear)
104 Spur
34 Pinion
2.26 roll out

This got the fastest run, but the lap times we a tick slower average.

So the next time we go back, the plan is to try to split that gear which should put us right at a 2.30 rollout. Plus we still need to free the car up a little on entry.

Sounds about right, sometimes it's that half a tooth that makes all the difference.

I was fast 2 weeks ago and won the main (under the lights, cooler temps outside probably around 72 degrees) ran the same motor this week during the day about 80 degrees at that same rollout and was a lap slower. That is when it gets frustrating, lol Cause then you don't know if you are battling weather, the track, setup, tires, or something else.

That is one of the downsides of racing outside, no consistency. At least on carpet if the outside temp stays pretty consistent cars are pretty good week to week.

Erock,

The target was to shoot for 40 laps. I believe the record is 41, but that was at a large event with awesome traction. This weekend 41 did get run at my event as well. (Congrats Larry Ruby)

This is what I ended up with

2.21 Tires
104 Spur
35 Pinion
2.336 rollout

That set up got awful hot, but was the fastest for single lap time, we dropped to a

2.20 Tire (from wear)
104 Spur
34 Pinion
2.26 roll out

This got the fastest run, but the lap times we a tick slower average.

So the next time we go back, the plan is to try to split that gear which should put us right at a 2.30 rollout. Plus we still need to free the car up a little on entry.

Looks good but does NOT mean a thing if you dont ADD Rpm of the motor to the formula!!

http://www.hobbytalk.com/modules.php?op=modload&name=Sections&file=index&req=listarticles&secid=3

erock,

When I had a dyno available...backing up a setup wasn't a problem... like RPM mentioned...w/o rpm numbers..all is lost. I use to track good numbers and be able to make changes accordingly, but that was years ago...and I've forgotten how much fun it is to make the LITTLE changes now that my son is coming up in the world of STOCK...

I hear that, i sold my dyno a few months back and I miss it mainly for tracking the RPM. With the advent of these High RPM stockers, I have seen RPM be 3000-4000 difference betteen motors sometimes. I typically change a tooth for each 800-1000 rpm change. It's crazy to think one Monster may need a few teeth difference compared to another Monster.

For example the benchmark at my local track is 54 laps and I have ran 54 laps with motors rolled 27 points apart. 27 / 6(which is usually the change in rollout per one tooth) = like 4.5 teeth difference in gear. Crazy

Did I mention I miss my dyno, lol

Rookie Question........I've been out of oval for some time and I know i could get different answers for this but what is the basic formula to get ROLLOUT? I know it's tire size, gear ratio, ETC......But what order, mutiply, divide. I forget.....Please help?

Rookie Question........I've been out of oval for some time and I know i could get different answers for this but what is the basic formula to get ROLLOUT? I know it's tire size, gear ratio, ETC......But what order, mutiply, divide. I forget.....Please help?

Run your oval car to the correct gear ratio that you like!!
Now you have a new motor running different RPMs.

What do you do? (note: same roll out)

Use this formula:

Rpm/ gear ratio = exsisting control motor number

new motor rpm/ exsisting control motor number = Ratio#

Ratio # - (present ratio) = difference #

Difference # - Spur size = New gear size

:wave:

RPM, you lost me with that formula. I remember it being more simple than that.I'll try to figure it out.

but what is the basic formula to get ROLLOUT?

Rollout = ((Pi x Tire Size) / (Spur)) x Pinion)
So for instance if you have a 2.22 tire, 108 spur and 40 tooth pinion your rollout is 2.58

3.14 x 2.22 = 6.9708
6.9708 / 108 = .064544
.064544 x 40 = 2.58

RPM, you lost me with that formula. I remember it being more simple than that.I'll try to figure it out.

The formula RPM was explaining is a more complicated formula typcially used by dyno programs to calculate gearing. Say for instance the above rollout (2.58) was ballistic fast. If that particular motor pulled 25000 RPM, you can use 25000 to find your control number. What this allows you do to is find the proper gearing for a motor say pulling 26,500 rpm



The laid out formula is:
RPM (1)/ gear ratio = control number.
RPM (2)/ control number = new gear ratio
...or if you want to figure in tranny ratio and tire size:
RPM (1)/ gear ratio (pinion & spur) X TR (tranny ratio)/ tire diameter = control number.
RPM (2)/ control number = gear ratio (P & S) X TR/ tire diameter.

So to complete my example you have Setup 1
Motor X - 25000 rpm
Gear Ratio - 108 /40 = 2.70
Control Number 25000 / 2.70 = 9259

Motor Z - 26500
Where should I rollout this motor?
Take 26500 and divide that by the control number of 9259 = 2.86
2.86 is your new gear ratio.
so say you stick with the same size tires and spur gear.
Then take 108 (spur size) and divide that by your new gear ratio of 2.86 = 38 (rounded) tooth pinion

So for a 26500 rpm motor to get it to run like the motor with 25000 rpm and a 40 tooth pinion you will need to go down to a 38 tooth pinion.

The formula RPM was explaining is a more complicated formula typcially used by dyno programs to calculate gearing. Say for instance the above rollout (2.58) was ballistic fast. If that particular motor pulled 25000 RPM, you can use 25000 to find your control number. What this allows you do to is find the proper gearing for a motor say pulling 26,500 rpm



The laid out formula is:
RPM (1)/ gear ratio = control number.
RPM (2)/ control number = new gear ratio
...or if you want to figure in tranny ratio and tire size:
RPM (1)/ gear ratio (pinion & spur) X TR (tranny ratio)/ tire diameter = control number.
RPM (2)/ control number = gear ratio (P & S) X TR/ tire diameter.

So to complete my example you have Setup 1
Motor X - 25000 rpm
Gear Ratio - 108 /40 = 2.70
Control Number 25000 / 2.70 = 9259

Motor Z - 26500
Where should I rollout this motor?
Take 26500 and divide that by the control number of 9259 = 2.86
2.86 is your new gear ratio.
so say you stick with the same size tires and spur gear.
Then take 108 (spur size) and divide that by your new gear ratio of 2.86 = 38 (rounded) tooth pinion

So for a 26500 rpm motor to get it to run like the motor with 25000 rpm and a 40 tooth pinion you will need to go down to a 38 tooth pinion.

now would that be with.... or without a receiver pack?? :drunk:

now would that be with.... or without a receiver pack?? :drunk:

I totally lost you on that one??

That's more like I remember! Thank you for the help. I'm not advanced enough to worry about motor RPM. I need to learn to hold my line first. I just needed roll-out so i could be in the same nieghborhood with the other cars. Thanks agian.

no problem RCracer00

Did you see the New Oval Racer thread? It might be worth a read for somebody getting back into the oval scene.

http://www.hobbytalk.com/bbs1/showthread.php?t=119093

Yes I did, I went threw it quick. I'd like to print it too look it over good. Thanks

The laid out formula is:
RPM (1)/ gear ratio = control number.
RPM (2)/ control number = new gear ratio
...or if you want to figure in tranny ratio and tire size:
RPM (1)/ gear ratio (pinion & spur) X TR (tranny ratio)/ tire diameter = control number.
RPM (2)/ control number = gear ratio (P & S) X TR/ tire diameter.


OR GRASSHOPPER !
for tire size :

RPM(1) X tire size / gear ratio = control number

RPM(2) X new or old tire size / control number = new gear ratio :wave: