INVADER - Nitro Slash drag car

[johnnydmd]

One thing I wanted to do to help with traction on the big end was build a proper rear wing. I was just using stabilizer fins I made from CF scraps, and the stock Vette promod wing doesn't have a lot of downforce. Most people put on extended ones from Caldwell Race Works and other places. I have so much scrap polycarbonate laying about anyway. Took me about an hour, and I had a wing Need to sand down the rough edges yet. I think I'll also leave it clear, I kinda like the look.

 

[johnnydmd]

Big weekend of testing! Saturday the weather was decent, upper 50's, sunny, no wind. Went out to a new spot (in a stadium parking lot). It had plenty of room for 66 or 132 ft hits, but I was sticking with 66ft until this thing would get a to b consistently. The surface was clean, though typical rough asphalt.

I started off with a super conservative "concave" tune, still at 30% power, and the slowest I could make the throttle go. I knew it would be slow, but I wanted consistent first. I got a couple of hits in with this tune, all were 1.9s at 38-39 mph. Then I did a "dumb thing", and turned my car while it was going too fast, cartwheeling it. I didn't have the body on (thank god), but it broke the wheelie bar mount adaptor (a 3d printed piece). No other damage other than a scratch on the cooling head. Went home, 3d printed a new adapter, and decided to go out the next day. Really have to get out of the habit of instinctually turning the car, and just let it slow down gradually to a stop before turning.

Well, the weather took a nasty turn. Low 50's and overcast. Windy as hell, with a pretty serious wind chill. Gusts were 30 mph. I was not really prepared for that - and had trouble getting the engine to a good operating temp. I was determined though. I started dialing up the throttle rate, and over the course of about 10 hits, got it all the way to 100%. Then I started dialing up the throttle speed, and moved it to 60%. The car was launching noticeably harder, times were getting down into the 1.8's and 1.7's. I was hitting the low 40's, which is pretty good. The g's were 1-2 for the most part throughout the entire time I held the throttle down. I only have one screenshot to show (more on that later). Pretty steep accel curve here, seeing 1.59 g's at 0.4, compared to 1g at 0.8 with the OS .21 tm that I was seeing before with the single speed trans.

I started moving the throttle exponential less concave and more linear. I was no where near the steep convex curve that I was using a couple weeks ago, so I wasn't quite as fast, but every hit was straight and consistent. I bumped the idle-up to 15%, and the trans brake held it, and was doing some seriously hard launches. I started getting into the 1.6s at this point, and upper 40's. I could definitely tell the car was getting close to the traction limit, as now I had to "drive" it a bit, but overall it was pretty straight. I should add that at this testing spot, there's a very slight sideways lean to the surface, so it's kind of fighting that to keep straight with some steering trim, and that is surely hurting the times a little. I like the spot though because nobody is around at all most days. My best run was 1.64 at 47 mph, and it cracked the 2g mark. Sorry I don't have a pic. I thought my GNSS was going to keep all of the records. Sadly (very) it did not. I know now to always swipe left to get a screenshot because you can't trust the app. At least I swiped the earlier run. When I got home I tried a bunch of stuff, and then just tried to fix it by clearing the cache, etc. Nothing worked - it wouldn't show the records, only the last thing you did. Then I uninstalled and re-installed the app, and it started working again. Too bad I cleared my cache

I'm still a little off of my goal to consistently hit sub 1.5's, but I need to try on a flatter surface and a better, warmer day. 1.5 is supposedly the "magic" number for 66ft passes according to the experts to be considered "fast". 1.2's are what the very fastest in the country can do in 66ft.

Meanwhile, my day ended after my brake adapter sheared after setting the brakes up a bit higher (again, better that then the transmission shafts). I had spares, but the wind was now howling at 40-50 mph, it was time to go.

 

[Doom!]

"The Invader" is so last year, just toss it and start something new, like maybe a starting light rig.

Glad your finally getting to test it out some, I know you've been itchin' to get it back out there.

 

[johnnydmd]

Glad your finally getting to test it out some, I know you've been itchin' to get it back out there.

The weather here has just been awful. Cold, windy, rainy. But at least all the pear trees are blooming and making my nose run and itch, lol.

 

[Doom!]

But at least all the pear trees are blooming and making my nose run and itch, lol.

I know that feeling to well, we have quite a few orchards near our house.

 

[johnnydmd]

Swapped out my tires for a softer compound, and am putting on bands. I also have a set of belted Reactions that I might stick on another set of wheels for comparison. I feel like the gold compound Hoosiers are softer and stickier though.

Weather is supposed to be pretty good (mid 60's) so going to do a bit of testing and racing with team members.

I still have this nagging urge to swap out the KE25 with a monster sized Force .38 though. I must have watched too much Home Improvement back in the day, lol.

 

[johnnydmd]

So, running the same tune on a different surface, I had different results. First, I did some spinny spinny testing to see how the tire bands and new tires worked, and wow, much, much less ballooning. Nice The softer compound tires were way stickier too. Mostly I spent my morning getting the tree and stuff set up, but I had about an hour to kill before the rain hit.

I ran this tune, with 50% throttle speed (Actually, need to double check what speed I have that set at).

I forgot my leaf blower, and the lot was diiiiiirty. Lotta dust, chips, you name it. Pollen. Lots and LOTS of pollen!

This lot is big and wide open. There is a solid 150 cool down too, with grass/dirt piles to stop you if you somehow manage to keep going, lol. So today I was going for the full 132 ft passes with reckless abandon. Time to let this thing eat!

Didn't get any video sorry. Too focused on getting stuff working.

The cool air wasn't helping with traction either. My first few passes had to be aborted at around 50 ft. The car was shaking loose - though it was launching quite hard and straight. I managed to get a couple A to B passes by easing off a little at that mark. At first I was a little terrified to get back into it approaching the finish, so I wasn't setting any records here. Now with an easy, accurate timer, this was quite a bit easier than having to reset the app on each pass, and get a better feel for the car as it warmed up more. I started getting a little braver, and was getting 2.7 on the tree, but still having to drive the car as it kept shaking the tires. Ok, that's progress. I turned on the GNSS and decided to record a pass on it for data. 2.95 on the GNSS, and 2.7 on the tree, which jives with what is expected - a .2 s or so delay from "real" time.

Note only 1.17g's. That's quite drop from 1.5-2.0 from last time out. Definitely reflecting traction woes. Also, the top speed of 47 is weak, but that's definitely from me getting out of it to save the car. It's definitely got a lot more in the tank, so to speak, using a 54t spur. (note, stock Jato does 60+ with a 57t and small block).

That flat spot in the accel curve is the tires shaking loose. I'm also looking at the curve dropping, but then flattening out, and thinking maybe I'm shifting a little late possibly, but hard to tell until I get a pass where it's sticking. I will go back this weekend and make sure the track is clean, and hopefully it's warmer and sunny. This weather is depressing this year. I think the tires are plenty sticky and performing well. I clean them with WD-40 and they are super sticky, but with that much pollen and dirt on the pavement (and I think those sandpiles in the background are part of the issue, lol), I was just fighting a losing battle.

 

[Doom!]

Sometimes conditions just don't want to play nice. But I guess it's good to know how it behaves in all conditions, you never know what you get on the day of an event.

 

[johnnydmd]

Sometimes conditions just don't want to play nice. But I guess it's good to know how it behaves in all conditions, you never know what you get on the day of an event.

I will save various tunes on my Noble NB4 for that very reason.

 

[johnnydmd]

Another weekend gone. Cold. Wet. Windy. So what to do? Well Sunday was Mother's Day, so that was spent doing the rounds to the mom's of the family. Saturday I was fighting salmonella poisoning after my wife tried to kill me on Thursday by feeding me a week old leftover chicken dish from the fridge. Spent most of the day watching hockey and working up enough strength to do some mods on the KE25. I did the basic "free rpms/horsepower" mods that RC Car Action wrote up some years ago. Picked up a new dremel, the "Dremel Lite" is garbage. Don't ever buy one of those. You'll get about 1 minute of use before it needs recharging. Got a D3000 that plugs in to replace it. The Dremel Lite will be my pit tool. After popping the sleeve out, I saw right away room for improvement, the ports were very sharp edged. Otherwise the engine was in great shape.

Started with the bottom of the sleeve:

Did the boost port next:

Went for the transfer ports after that, and added guide channels.

Not really all that hard to do, but delicate. Don't need much other than what I pictured. Polishing compound finished it off and got it super smooth.

 

[Doom!]

Sucks about the chicken, some people will do anything to sit around on the couch!

 

[johnnydmd]

I was looking to replace the grille graphics, the ProLine ones really do suck badly.

Stock ProLine:

I made this from a photo:

But then I saw this while searching for the one above:

LOL. Super cheesy for a street car I think...but for a drag car? Hmmmm....

(Mockup)

 

[Doom!]

Love it!

 

[WickedFog]

Love it x2

 

[johnnydmd]

Dang, my mockup was pretty spot on -

I really should make the grill parts transparent, and have light behind it, lol. Ok.

Sunday I got to set up the track and test. It was 80, sunny, no wind. Parking lot was FILTHY with dust. I blew it clean, but in hindsight wish I would have done it more. Each pass the car came back with very dusty tires.

The tree timer worked great, despite the bright sun. I should have brought a tent for the tree though, it was so bright that I couldn't see the digital timers without cupping my hand over them, and even then it was hard. So...damn...bright. I fashioned a shroud out of cardboard, but the sun was coming from behind and so that was useless. Tent would have been much better. It was so bright I could barely see my phone and my GNSS was having trouble finding satellites. I did get it working briefly, but too much hassle, and why bother when I have a working, accurate timer.

I couldn't see the countdown lights at all (yellow). The green was pretty visible though. Spent much of the morning chasing a tune. Definitely things had changed with the port job. That engine really opened up, it was very, very responsive. Had an audience too, as firefighters and cops were doing parking practice in the stadium lot. They were nice enough to stay out of the cooldown area, and came over and chit chatted a bit. Most of them wanted to buy drag cars, lol.

Once I got the engine purring and tuned, I started laying down some licks. First two passes had to abort, blew the tires off at 50 feet or so. There is no question I have to pedal after launching - there's just no good way to electronically control the throttle that far out. My launches were really hard and straight though! I still have a LOT of power taken out on the launch, and I surely can start dialing it up. Third pass was the charm. Easily the fastest, hardest hitting lick I've done in this car. I knew it was a good one! Tree timer showed 2.4! I laid down a few more, but all were squirrelly and had to really drive/pedal. My wife showed up at that point, and wanted to take some video and pictures. I got the car ready, and blasted off another great one - but at the very last 10 feet the car started veering and it clipped the speed trap. The timer relay box went into orbit, I saw pieces of the car fly off. I went down, the car looked ok, other than the canards on the left side had been knock loose/off, and a small dent near the wheel well, which popped back out easily enough and a couple of scratches. Chassis was fine! Timer relay was fine (really glad I built that foam/lexan box for it! That lick rivaled the 2.4 one, if not even faster. Don't know what the time was because when I went to look I accidentally broke the starting line beam with my foot and reset the timer, lol. (I actually did that a bunch of times - wouldn't be an issue if not having to put my hands over the timer to see it and forgetting about the beam).

Oh, the video. Well that would (would) have been epic to see that finish. However, due to the bright sunlight and not being able to see phone screens, the video began with me at the finish line picking up the loose pieces and relay box. Am I the only one that really hates taking videos when racing? I mean, it seriously stresses me. I really just want to not be bothered, so that's my wife's job Maybe next time she'll be able to get a good one.

Next weekend my team is planning on getting together and doing a cash days, weather permitting.

 

[WickedFog]

That looks killer!

 

[Maximum_Quake_Pro.com]

Force .38 is not what you want in that, torque monster at lower to mid rpm range, for moving heavy trucks

 

[johnnydmd]

Force .38 is not what you want in that, torque monster at lower to mid rpm range, for moving heavy trucks

Yeah, I'm not going in that direction. Sticking with the KE25 that I've ported and seeing what I can get out of it for now. I have a spare SH .28-8 that I might try out as well, as that one is pretty good on the top end.

 

[Maximum_Quake_Pro.com]

Yeah, I'm not going in that direction. Sticking with the KE25 that I've ported and seeing what I can get out of it for now. I have a spare SH .28-8 that I might try out as well, as that one is pretty good on the top end.

I think the sh is a losi 454 with more porting maybe

 

[johnnydmd]

Well this was a decent hit Getting closer. As noted by my teammate, it knocked the tires off when shifting to second gear, which is when it started getting squirrelly on the big end. I think a little before he was pointing at and seeing it. Didn't have the tree with us, storms were heading our way and didn't want to get caught in that trying to break it all down. Stopwatch app on my computer seems to put this run in the low 2's.

I'm actually changing the gears and clutch/bell out this week to a Mod1 setup and using a vented Reds bell with Tetra four shoe adjustable. Gearing will be roughly identical, maybe fractionally taller.

I had another good run that was videoed but the quality was poor so I didn't upload. It was straight as an arrow, and again, in the low 2s range. I think that I have the shift point perfect now, but I'm going to need to back out another 1/4 turn on the slipper to keep that from having too much of a jolt when shifting into second. I still am using the same throttle curve, but in two weeks when we get together again, I'm going to run some more aggressive ones.