PDA

View Full Version : Dialed to rubbish; fast motors suck.


JeremyC
2010.01.31, 08:04 PM
My car was working amazingly with the Standard BB motor. It was predictable, neutral, had good rotation, etc. It was great.

But down the straight the other cars were whipping past me. These yellow label motors are just so much faster. So, I stuck one in my car and proceeded to have one of the most annoying days racing I've had in awhile.

The first time I gave it throttle I knew that my Kyosho slick 20 rears were just not going to cut it. Not only would the car spin on throttle it would kick out really badly at speed when turning and braking. I immediately switched to K20 radials, and the car felt decent.

Ok, great, I think to myself, "I got the tires right it should handle great". Wrong. The reason being that with such a fast motor the time you are on and off throttle changes a lot. Mostly, you are off throttle earlier; and that totally messed me up. I was used to having just a little weight on the front of the car at turn in, but with this monster motor the front end of the car was completely settled and when I would turn the car would snap right into the wall. GRR

But I still needed my front grip when turning on-power, so I don't know that I can put harder fronts on. So... it took me a good 30 minutes of wheel time before I could even drive the car around the track without looking like a jack ass.

After 45 minutes of driving I got my qualifying time up to a respectable 47 5:01 at BKH, but I did a 50 5:04 the last time I was there with the slower motor. I'm seriously thinking about just sticking the other motor back in; I had more fun.

dvsstrike
2010.01.31, 08:52 PM
just stick with the motor you are more comffortable with. speed is nice but whats the fun if you can't drive it...btw what class are you running? pn stock or just stock?i.e atomic bbstock , stock r...speedy?

JeremyC
2010.01.31, 09:37 PM
just stick with the motor you are more comffortable with. speed is nice but whats the fun if you can't drive it...btw what class are you running? pn stock or just stock?i.e atomic bbstock , stock r...speedy?

I run at two hobby shops, and both have the same rule: Anything goes with an Atomic Stock yellow label motor being the fastest motor you can run.

I'm sure I just need more time with it, but it is frustrating going from feeling really confident about the car, to feeling like I'm struggling to get the car around the track.

chad508
2010.01.31, 10:02 PM
i learned a long time ago. slow is fast. look at most races stock normal will turn the same if not more laps than mod.

Action B
2010.01.31, 10:05 PM
I have been racing for two years and I have a decent amount of experience. My favorite motor is the PN 70 turn by far. For big tracks I use an atomic standard sometimes. Usually the fastest car around the track is not the fastest car on the straightaway. I try to work towards consistency more than anything.

Sinister_Y
2010.01.31, 11:18 PM
My feedback and experience dictate that if you get your car working as you want with the faster motor, the car will handle that much better when you stick in the slower motor.

For example, in 1/10th days, we used run stock class exclusively. Got the car "dialed in". Then threw in the mod motor and setup was crap. Tuned the car with the faster motor and found all the areas where the original setup was bad, except you didn't know since the car was not being pushed to it's speed limit.

Once we got the cars dialed in using the mod motors, we'd stick in the stock and our best lap times were smashed.

For races though,don't screw around. Leave the big tuning changes to a backup car or do it on training/setup days.

There will always be minor tweaks that will need to be made for the layout and track grip during race day.

EMU
2010.02.01, 03:30 AM
I know exactly how it feels to have a car that is near perfection, then you increase the power just a little bit, and the setup is just wrong.

One big difference between the Standard and the Stock, is how much low more torque the Stock has. It does have a little more drag brake than the Standard, but you still have to let off a little earlier, since speeds are higher. Did you gear the motor any differently than the Standard?

Here are a few comparison graphs of the two motors:
http://www.atomicmods.com/images/Pages/Atomic_Standard_Stock_Motor_Torque_Curve.jpg
http://www.atomicmods.com/images/Pages/Atomic_Stock_Torque_Curve.jpg
You can see how much more torque there is with the Stock, also it takes more than a second longer with the Standard than the Stock to spin to full speed with the flywheel that was used for testing. It takes the Stock about 2.5s, and the Standard about 5s to spin up to 20,000rpm.
http://www.atomicmods.com/images/Pages/Atomic_Standard_Stock_Motor_RPMs.jpg
http://www.atomicmods.com/images/Pages/Atomic_Stock_RPMs.jpg

http://www.atomicmods.com/images/Pages/Atomic_Standard_Stock_Motor_Power_vs_RPMs.jpg
http://www.atomicmods.com/images/Pages/Atomic_Stock_Power_vs_RPMs.jpg
You can see that the curves are very similar, however, if you look at the numbers you will see how much more power there is throughout the revs with the Stock motor than the Standard.

The huge increase in power changes how you have to setup and drive the car. Typically, the car will need more precise use of the throttle in the corners. You have to wait until you are exiting the corner to get on throttle instead of getting on throttle early as you clip the apex.

Driving with the Atomic stock, is very close to driving with a modified motor. You have to search for grip instead of corner speed. Im with Sinister, where I like to setup my cars with more motor than I plan to race it with. My setups are closer to stock setups than modified setups, but I have thrown mod motors in them and run in modified classes successfully, although throttle control was much harder...

I always try to adjust the settings on my throttle so that every motor feels similar... I adjust curve and punch until it feels right. You can also adjust the throttle speed in different sections of the throttle throw, to smoothen out input sent to the car.

If I were you, I would keep the motor in for a little while... adjust to it a little, make a few small setup changes... see what your fast laps are, and what your average laps are. The faster motor should have a larger difference between the fast lap and the average lap... I always want to be within one second between fast and average lap. If I am outside of that field, I know I need to make changes to increase stability/consistancy. Sometimes you have to increase the fast lap to lower the average lap...

I prefer the ATM Standard for 2wd and ATM Stock for AWD. I think that for most tracks, the Stock is too fast for 2wd, but that also creates another challenge... Try using slow batteries with the Stock, you can really tame down fast motors with slower batteries. That is one reason that people like the Stock, you dont need fast cells to be competitive, since it is overpowered with good cells.

cosmicsoul
2010.02.01, 08:11 AM
If your car is kicking out try using harder springs in the front until it stops.

Loosen up your diff a little, try a smaller pinion. Example 12 to 10 tooth.

Like EMU said slower batteries could definately help.

Action B and Chads advice is the best of all! Go slower to go faster consitency and staying out of wrecks are what win races for about 90% of us!

MikeL
2010.02.01, 08:55 AM
You diff setting is also a lot more important with a fast motor. I have always struggled with mod mini-z, and I am not happy that the standard is no longer teh USA motor, that motor was a good speed.

ianc
2010.02.01, 11:55 AM
K20 slicks rear and K30 slicks front should be fine for about any track, but you're going to have to tweak the suspension to be able to put that power to the ground. Driving style will of course also be affected for any given track.

All you need to do is train your finger not to press down so hard for so long. :D

Seriously, just be more gentle with the throttle, but be aware you have a significant power reserve available when necessary. If it helps, you can try setting your throttle EPA way down until you get used to it.

ianc

Eman
2010.02.01, 12:38 PM
I went from a PN70T to a Atomic BB Standard in a MR-015 without any problems. I had to adjust the way I drove it. I didn't have anything happen like you are describing. I'm wondering if something broke or was tweaked during the installation of the motor that has gone unnoticed.

yasuji
2010.02.01, 12:47 PM
i tell this to most of my drivers....to set there car up with a fast /mod motor and dial it in...yes it is harder to drive....yes it is faster....but when u put a spec/stk motor back in the chassis , the set up WILL be better and they will be able to go faster!

JeremyC
2010.02.01, 06:12 PM
Thanks to everyone for your feedback.

I want to point out that after I put the K20radials on the rear of the car, the car itself wasn't so horrible. I think it had a little too much front bite, and I want to try a stiffer T plate and/or stiffer front springs.

I really think most of the problem is that I couldn't adjust quickly enough to the much faster car. It doesn't help that I'm still using a KT-18 and can't adjust in nearly as much control as I could on my helios. (An aside is that I can't find an ASF module for my left arm.)

My plan is to leave the car as it is and just dial the throttle back a bit. I know that I should get the experience of driving a faster car, but unless I can get a similar feeling of control over the car with the fast motor I think I'll go back. I just don't feel as connected to the car.

pressure
2010.02.01, 11:25 PM
Hey Jeremy, Saw that you were having problems but didnt know exactly what was wrong. I run the Atomic stock and Im starting to play around ith the diffs especially at different tracks. At BKH its a shorter track I started running loose diff with thin oil the motor gets up to speed but I lose some of the torque, it works for my driving style. I notice that my motor runs hotter but my lap time seem consistant ( if I can stay off the wall) I ran atomic 30 in front and kyosho 30 slick in the rear(usually run radials but had to run my back up car= traction roll) I run the same gearing and tune with diff it seems to work for me. stop by next race Im working on 2 cars for winternats on the 27th:D

ianc
2010.02.02, 09:38 AM
I want to point out that after I put the K20radials on the rear of the car, the car itself wasn't so horrible.

Yeah, but this goes back to an earlier post of yours; once the tread wears off, you're back to square one. Best to just have consistent handling over the (long) life of the tire. Look to suspension tweaks to get you more grip\comfort.

Of course, there definitely is a power limit for the amount of grip a certain track offers, so if your motor is just too crazy fast for a particular venue, you're better off with less...

ianc