66FT no-prep drag racing

[ahr43]

Fleshing out runs on a 1/10 scale 1/8 mile RC drag strip. Full no-prep 2WD/RWD. No-prep surface and no-prep tires. 66Ft lane with 132ft shutdown.

First image is from start, staging (blue pipe), roll-in (red pipe) and 66ft coned course with 6ft speed trap. Timing is GNSS speed meter. No E.T. (Elapsed Time) - mph only. Second image looking back track from shut-down to start. Third image, the S/C #129 Senton.

Laid down 14 passes today with the 2WD Senton (Typhon body). Best pass 38mph at 98% THR. 2s x 5300 60C LiPo. That puts the car about 5mph off pace. It's a 43mph break out Super/Comp Class. No restrictions other than 2s -or- 3s battery power.

 

[332_RC]

That's awesome! Cool setup. I'm guessing 43mph is scale 1/8 mile fast! Would that be equivalent say to 100mph+ 1/4 mile 1:1? I have off road & on-road RC's, I've been interested in 132ft racing.

 

[johnnydmd]

That's a good looking spot!

 

[ahr43]

Thanks, guys.

@332_RC. Glad you're interested in 132ft no-prep. johnnydmd's got a good link going with his ongoing nitro build. Check it out. 132ft is the RC standard. 43mph is just a speed to begin with. Figgered if acceleration remained linear, that'd be 86mph at 132ft. About what speed my electric top fuel car was running back in the day. Maybe some of the 132ft gang could check their timing slips for half-track (66ft) speeds to see how close 43mph is to what their turning? Stick around. More to come (hopefully).

@johnnydmd. Yeah, industrial site. Wide smooth road. No storm drains. Relatively little crown to the surface. Just enough to drain water. Quiet as a tomb on weekends. Got an even better site I've got to seek permission to run on. Both sites within 5 miles of home.

Cheers. -AC

 

[ahr43]

Regarding the Senton 2WD. This is the baseline set-up. The dual sport street/strip set-up if you will. With baseline performance in hand, can begin mods to DragSpec.

Mostly playing with radio settings yesterday. Two calibration runs at 50% THR; two tuning runs at 75% THR; then began banging the throttle with 90-98% THR runs. Getting loss of traction wheelspin when the radio came off its -60 TH Expo setting. Switching over to -60 TH Speed instead of Expo made for a more linear power transfer and took out the wheelspin.

Geared 20/91//4.55. 55% RR weight bias. Thinking about moving the FR ballast to the RR until late in the runs. Switching to a fresh 7.4v 2s began carrying the front wheels about 6ft out in a slight power wheelie. Think for now, will leave the FR ballast in place. Already fit a set of JC Dotek RR tires. Got a long laundry list of mods to do. This is a start.

Regarding the speed trap at the end of the run. Previous to yesterday, was chopping the throttle as close to end of course as I could judge. Think I was getting some carry-on in speed and not getting accurate 66ft speeds. Chopping the throttle now at entering 6ft speed trap gives noticeably slower speed readings - about 2-3mph. ESC set at 10% drag brake. Thinking of going free-wheeling to get back at least 1-2mph in the speed trap. Using ABS braking so can probably do that without experiencing side skid when braking.

 

[johnnydmd]

132ft gang could check their timing slips for half-track (66ft) speeds to see how close 43mph is to what their turning?

I haven't done a 66 ft time since 2022, but as I recall, that is about where I was at.

 

[DavidB1126]

At the old local track. we used to have a carpet drag strip in the back. It was called "Strip 66" since it was 66ft. With about a 20ft braking zone / shut down. He used a Traxxas Drag tree and Traxxas app on his iPad. Drag racing wasn't really popular there. I did a couple runs on it with my race buggy. Did a little test. B74 vs a Bandit VXL. If I remember correctly. I got 32mph in about 2.3 seconds. (This was with my race buggy, 2s lipo, 13.5T motor and pretty conservative gearing, so top speed is pretty accurate for that) If I did my slash or rustler, I would probably hit 40ish mph. We tried to set up some drag racing there. Really didn't work out as it was April last year and the outdoor season was already started. I seen a few Losi Mini Drag cars and a few custom FWD drag cars. The whole project didn't last long as the place next door was moving their wall over more to get more space, but it didn't happen so we didn't put the track back up.

 

[ahr43]

Looked like traction was good on 'Strip 66.' For shut down track back in the day used a safety catch net. Easier on the cars. Even with a 180ft shut down back in the day, electric top fuel and unlimited classes were using the safety net as final "brake."

[ Edit: On my 66ft course, shut down is coned-off at 132ft. Rules package stipulates competitors must slow the car and be under control to make the turn onto the return lane in that distance. At end of run terminal velocity of 43mph equates to ~63ft/sec. Doesn't take long to eat up that 132ft shut down. Makes the run more challenging. After all, it is "Radio Control" - both going and slowing. ]

Always thought Bandit would be a good drag package. Seen a few extended w/b Bandit conversions that were good runners. May yet build one.

 

[332_RC]

Thanks, guys.

@332_RC. Glad you're interested in 132ft no-prep. johnnydmd's got a good link going with his ongoing nitro build. Check it out. 132ft is the RC standard. 43mph is just a speed to begin with. Figgered if acceleration remained linear, that'd be 86mph at 132ft. About what speed my electric top fuel car was running back in the day. Maybe some of the 132ft gang could check their timing slips for half-track (66ft) speeds to see how close 43mph is to what their turning? Stick around. More to come (hopefully).

@johnnydmd. Yeah, industrial site. Wide smooth road. No storm drains. Relatively little crown to the surface. Just enough to drain water. Quiet as a tomb on weekends. Got an even better site I've got to seek permission to run on. Both sites within 5 miles of home.

Cheers. -AC

Thanks for the info! I've got a few street bashers. Infraction 6s & 3s and the 3s Senton I'm converting into street. I have a GNSS. I have some spots I can tape off to try out. Good to know what is FAST for 66/132. Only rig i have that would get close to 80 is my Infraction 6s for 132ft. I'm thinking I'll try out 66ft, see where one of them is at. Thanks man!!

 

[johnnydmd]

Figgered if acceleration remained linear, that'd be 86mph at 132ft.

It won't be linear. It all depends on gearing, and with electric, the peak acceleration is at the start, and it gradually decreases with RPM.

 

[ahr43]

Revisiting Event 4 to finish it out. Rustler Rock 'n Roll had a bye run Round One into the Semi-Final. Good thing too. Seriously in need of a wheelie bar. Stood her up on the RR bumper two runs. Never got THR setting above 80%. Triggering off the wheelie, got chassis slap up front the second time. Thought the FR shock springs were too stiff when setting her up in the shop. Hmm. Maybe not. That and three-hole shock pistons and 25wt oil transfer weight to the rear all right. Kinda fall short on damping coming off a wheelie though.

Also had 67% RR weight. Like my cars to sit static at about ~60%. Probably a factor as well. May have to live with that.

Wheelie bar, lower the ESC punch and gear higher for the semi-finals. Down on speed she is too needed to make the 43mph break-out. 30.37mph at 80% THR won't get it done. Power unit gives me 3s option. Need to get her sorted out on 2s before slapping more volts to her.

Hotter than blazes already. Lucked out and found a shady spot to pit. Put me back to an old run site. Got runs in before the sun took the shade away.

Thanks for looking in. Cheers. -AC

 

[ahr43]

Hanging the R43X back on the pegboard pending further maintenance, noticed a peculiar thing. P-L Hoosier slicks appear to have different diameter inside and outside of mold center line.

Not sure if it's a mold anomaly, a characteristic of mounting to the 2.2/3.0 SCT wheel, or just my old eyes seeing things?

Tire appears distended or stretched to a larger diameter more so on the inside (3.0in) bead than on the outer (2.2in) bead. Scrub-in pattern after a days running clearly depicts only the inner side of tire is getting traction. Anyone else experience this? Wondering if shaving the tire inserts might correct this?

Did sort of notice this Friday setting RR camber to a +1 to get a scrub pattern during 33ft tests out front of the house. More apparent when looking straight down on the tire from the top.

Comments? -AC

 

[johnnydmd]

Cool! Interesting about the Hoosiers, never noticed that before.

 

[ahr43]

Cool! Interesting about the Hoosiers, never noticed that before.

Next event you go to johnny, would you ask around your buddies running Hoosiers how they prep their tires? Esp. inserts. Some of the YT vids I've watched on no-prep guys are not running inserts to get a wider flatter footprint. Wondering if this is how Hoosiers are getting prepped?

Also, what make wheels and width they are running? My Hoosiers are mounted to a pair of P-L Raid 2.2/3.0 wheels. Rambling here, but thinking of the option of going back to an open cell insert? The P-L blue closed cell inserts are firm compared to, say, a JC white open cell. Open cell insert may allow the tire to sit flat for a better footprint?

Thanks for looking in and commenting. Cheers. -AC

 

[johnnydmd]

I run Hoosiers on both of my small-block cars. I used tire bands made specifically for them you can find on eBay. For wheels I'm using https://www.amainhobbies.com/ssd-rc-5-hole-one-piece-drag-rear-wheels-black-2-ssd00551/p1469260 which are super light and strong. Otherwise ProLine makes some plastic ones that are nice if you don't want to spend on aluminum ones.

I prep my tires using WD-40 a few minutes before a pass. It reacts with the rubber, making it tacky. I've routinely been told at events "Ditch the Hoosiers get Voodoos and use Bug Guts" and I politely say "ok" then I make a pass while they get about 10 feet before spinning out.

 

[Doom!]

For wheels I'm using https://www.amainhobbies.com/ssd-rc-5-hole-one-piece-drag-rear-wheels-black-2-ssd00551/p1469260 which are super light and strong. Otherwise ProLine makes some plastic ones that are nice if you don't want to spend on aluminum ones.

Amazing how many things are out there I didn't know existed.