INVADER - Nitro Slash drag car

[Greywolf74]

Yeah I get it about Integy, definitely not good for bashing (though my old Tmaxx racer has held up, probably just got lucky, plus I don't bash it). I hear their stuff is pretty hit or miss). I used it on this build for the weight and look since it's just a drag racer.

It definitely looks sharp. I hope she runs as fast as she looks

 

[Doom!]

She looks naked!

 

[johnnydmd]

Put in the 24/66 gears, and drilled out the clutch shoes some, figured what the heck, go for it. Will be testing on Saturday for sure.

Nearly done the chassis mods, just have to cut the CF tank mount, and it's done. Oh, and I found a lighter front bulkhead that's a better color match to the arms

 

[Doom!]

If I did nitro, this is the one I would want.

 

[johnnydmd]

Well, I got the tank in. Took some nice pictures. Went out and tested.

Ran on Saturday evening, it was not too hot out. The car seemed to be running a bit richer with the new tank. The temperature was roughly the same, and pressure, etc - but I didn't give it much mind, and leaned out the HSN a little.

Ran a couple of times, and while it was faster, it's not where it needs to be - though it was very straight and consistent. Not getting hard launches, so I definitely need to drill the clutch out a bit more. I didn't use any tire sauce, and judging by the sound I saw in the video we took, and by the data, I was losing traction when the engine hit it's power band. Several runs of 3.2s that were 45-50 mph.

I will say though that the acceleration curve was markedly steeper with the 24/66 gears, so I'm definitely on the right track with the clutch, as I think I can attribute that to it hitting in at higher rpm. In the video, I could hear the engine suddenly rev up at around 30 feet or so, and I think that's where the flat part in the acceleration line is.

I went out yesterday in the early afternoon. It was around 80 out, and I noticed that the car would barely stay running. It was spitting a lot of fuel out, and when I revved it, it would die every time. I leaned out the LSN and HSN, but this is a 3 needle carb, and the 3rd needle is inaccessible with the engine mounted, and dummy me didn't have the right wrench to pull the engine. I think I leaned both the HSN and LSN by a half turn, and it was running better, but the mid speed needle was still a problem. But this was weird to me...I've never had to lean it out this far, in any conditions. The only thing different was the 1oz Sullivan tank vs the stock 5oz Slash tank. I managed to bust a couple of runs off, but the engine was clearly not performing all that well.

Again, lost traction at the power band, but also nice steep acceleration at the start.

My final run I think the tires stayed hooked up, but it slowed down at the end, because (and I'll elaborate) I lost radio control.

The car was still spewing a lot of fuel, running very rich. I didn't want to lean the HSN/LSN any further without touching the MSN, so I called it a day. Plus a cop showed up (just sitting in the lot doing paperwork or taking a nap, and I didn't wanna get yelled at, lol). He didn't seem interested in me though

So I'm using the FlySky GT3B, and I've been having issues with the radio cutting out on the big end, sometimes even before hitting the traps. I've got the wire in a tube and pointed up, but inside the body, but still, that's horrible range. It's a 40 dollar radio, so I guess that's deserved, and I need to invest in a better radio for this car. I'm losing radio on every run, so it's not a fluke.

Now, in the "learn something new every day" section...

In my other build, I'm using the same Sullivan 1oz tank, and am finding the engine running extremely rich, even when down 1/2 turn from factory break in settings. Having this same thing happening to Invader made the lightbulb click off - it's the tank. More accurately, it's the size of the tank - and that the tiny tank is generating too much fuel pressure. This is why when revving it, it's stalling - more exhaust, making more pressure, and flooding. So this is kind of tricky, I think. I can, and have leaned out the needles, but I don't want to get it to a situation that when the tank is less full that it get's too lean. My thoughts for correctly dealing with this would be to mitigate the air pressure coming back into the tank. So first, I'm going to try clamping the hose to restrict the air flow some. If that doesn't work, I'm thinking of putting some inline expansion tank in, but that seems a little awkward and adding additional weight. I'll try tonight to run the engine with the clamped hose, to see it it's a little better. At least now though I have the common thread between my two rigs having this issue, and a decent idea of what's happening.

 

[Greywolf74]

I can't speak to the tuning aspect of what you're doing as I'm not the best engine tuner, Ill leave that part to @cbaker65 or one of the more knowledgeable guys but I've always heard and I've even heard Baker say that you really dont want to mess with that MSN. Just a thought on that.

The one thing I can speak to is the GT3b. Theres an issue with the antenna on your receiver. Thats the way they act when they get damaged and they can get damaged pretty easy it seems like. I've had to replace a fair amount of those RXs for that very reason. The receivers are cheap after all but when working correctly the GT3b has amazing range. Its at least a 1/4 mile or more. I used a GT3b for doing speed runs with my high speed Rustler and I was doing at least 1/4 mile runs, if not longer. I went with that radio because people back then (I've had mine for over a decade) said that it had a better range than the Spektrum radios.

 

[Tunedfrog]

Well, I got the tank in. Took some nice pictures. Went out and tested.

View attachment 134355
View attachment 134356

Ran on Saturday evening, it was not too hot out. The car seemed to be running a bit richer with the new tank. The temperature was roughly the same, and pressure, etc - but I didn't give it much mind, and leaned out the HSN a little.

Ran a couple of times, and while it was faster, it's not where it needs to be - though it was very straight and consistent. Not getting hard launches, so I definitely need to drill the clutch out a bit more. I didn't use any tire sauce, and judging by the sound I saw in the video we took, and by the data, I was losing traction when the engine hit it's power band. Several runs of 3.2s that were 45-50 mph.

View attachment 134357

I will say though that the acceleration curve was markedly steeper with the 24/66 gears, so I'm definitely on the right track with the clutch, as I think I can attribute that to it hitting in at higher rpm. In the video, I could hear the engine suddenly rev up at around 30 feet or so, and I think that's where the flat part in the acceleration line is.

I went out yesterday in the early afternoon. It was around 80 out, and I noticed that the car would barely stay running. It was spitting a lot of fuel out, and when I revved it, it would die every time. I leaned out the LSN and HSN, but this is a 3 needle carb, and the 3rd needle is inaccessible with the engine mounted, and dummy me didn't have the right wrench to pull the engine. I think I leaned both the HSN and LSN by a half turn, and it was running better, but the mid speed needle was still a problem. But this was weird to me...I've never had to lean it out this far, in any conditions. The only thing different was the 1oz Sullivan tank vs the stock 5oz Slash tank. I managed to bust a couple of runs off, but the engine was clearly not performing all that well.

View attachment 134358

Again, lost traction at the power band, but also nice steep acceleration at the start.

My final run I think the tires stayed hooked up, but it slowed down at the end, because (and I'll elaborate) I lost radio control.

View attachment 134360

The car was still spewing a lot of fuel, running very rich. I didn't want to lean the HSN/LSN any further without touching the MSN, so I called it a day. Plus a cop showed up (just sitting in the lot doing paperwork or taking a nap, and I didn't wanna get yelled at, lol). He didn't seem interested in me though

So I'm using the FlySky GT3B, and I've been having issues with the radio cutting out on the big end, sometimes even before hitting the traps. I've got the wire in a tube and pointed up, but inside the body, but still, that's horrible range. It's a 40 dollar radio, so I guess that's deserved, and I need to invest in a better radio for this car. I'm losing radio on every run, so it's not a fluke.

Now, in the "learn something new every day" section...

In my other build, I'm using the same Sullivan 1oz tank, and am finding the engine running extremely rich, even when down 1/2 turn from factory break in settings. Having this same thing happening to Invader made the lightbulb click off - it's the tank. More accurately, it's the size of the tank - and that the tiny tank is generating too much fuel pressure. This is why when revving it, it's stalling - more exhaust, making more pressure, and flooding. So this is kind of tricky, I think. I can, and have leaned out the needles, but I don't want to get it to a situation that when the tank is less full that it get's too lean. My thoughts for correctly dealing with this would be to mitigate the air pressure coming back into the tank. So first, I'm going to try clamping the hose to restrict the air flow some. If that doesn't work, I'm thinking of putting some inline expansion tank in, but that seems a little awkward and adding additional weight. I'll try tonight to run the engine with the clamped hose, to see it it's a little better. At least now though I have the common thread between my two rigs having this issue, and a decent idea of what's happening.

I'm not into drag racing but I recognize beauty, smoking hot job man, you should be proud of yourself.

 

[Greywolf74]

I'm not into drag racing but I recognize beauty, smoking hot job man, you should be proud of yourself.

She is beautiful, thats fo sho! Makes me want one just like it lol

 

[Tunedfrog]

Nobody around here drag races RCs, in fact I have yet to see anybody run any RCs.
I would consider building a shelf queen for sure though. I would look like a damn fool
jumping up and down with excitement at the high school parking lot with the win....

 

[johnnydmd]

I can't speak to the tuning aspect of what you're doing as I'm not the best engine tuner, Ill leave that part to @cbaker65 or one of the more knowledgeable guys but I've always heard and I've even heard Baker say that you really dont want to mess with that MSN. Just a thought on that.

The one thing I can speak to is the GT3b. Theres an issue with the antenna on your receiver. Thats the way they act when they get damaged and they can get damaged pretty easy it seems like. I've had to replace a fair amount of those RXs for that very reason. The receivers are cheap after all but when working correctly the GT3b has amazing range. Its at least a 1/4 mile or more. I used a GT3b for doing speed runs with my high speed Rustler and I was doing at least 1/4 mile runs, if not longer. I went with that radio because people back then (I've had mine for over a decade) said that it had a better range than the Spektrum radios.

Ah ok, thanks. I have another one in one of my trucks, so I'll give that a shot and see how it does, and then get a new receiver(or maybe pull this one apart and see if something came unsoldered, etc).

 

[Greywolf74]

Ah ok, thanks. I have another one in one of my trucks, so I'll give that a shot and see how it does, and then get a new receiver(or maybe pull this one apart and see if something came unsoldered, etc).

In my experience with them its usually, but not always, a crack in the antenna wire somewhere. Hopefully yours is something that can be simple and resoldered but I never figured out how to fix any of mine. Not that I spent a lot of time trying. Theyre really cheap so after taking the first one or two apart I was just like screw it and started keeping 2 or 3 spares on hand lol

 

[Doom!]

Sorry about the performance problems. I know you'll get there.

 

[johnnydmd]

Definitely tracked it down to the fuel tank. And yeah, messing with the MSN was a no-no, that thing needs to stay at the factory setting for sure. Leaning it slightly caused fuel starvation when opening the throttle. I hooked up the original tank, and with a few needle tweaks had it running perfectly again. Hooked the Sullivan back up, and yeah, super rich, stalls after blipping the throttle every time. Sigh.

I ordered a 75cc Jato tank. Actually ordered two, since the funny car has the same issue. Those little Sullivan tanks simply don't work for these engines.

 

[Doom!]

Good to hear you've got it figured out. I don't know how you guys can trouble shoot Nitro stuff....to many things for my brain to balance.

 

[johnnydmd]

Good to hear you've got it figured out. I don't know how you guys can trouble shoot Nitro stuff....to many things for my brain to balance.

I gotta be honest, this one really tested my patience! Had a couple of people on the FB groups I frequent who built RJ Speed cars using those tanks affirm my findings, saying they had similar issues and wound up using Traxxas or similar tanks in the end. I really think it's the size more than the design.

 

[johnnydmd]

Got the Jato tank in, just had to mod it only slightly to make it fit securely. Tested the mix a little, didn't go out to make any full runs yet with this one, as I was focused on the other car. Seems to work well though, and I'm getting that OS .21 tm dialed in a little better I think.

 

[Doom!]

@johnnydmd Does it change the weight/balance much by changing the fuel tanks, or were they close enough in size not to matter much? I know squat about nitro so I'm just curious.

 

[Greywolf74]

For a split second there I thought that said "I tasted the mix..." I was like "Uhhhh someone better check on Johnny!"

 

[johnnydmd]

@johnnydmd Does it change the weight/balance much by changing the fuel tanks, or were they close enough in size not to matter much? I know squat about nitro so I'm just curious.

The Jato tank is 1/2 the size of the Slash tank, so it's a decent weight savings especially when you consider fuel (assuming you need to keep it at least half full to prevent fuel sloshing, etc). Compared to the Sullivan, it's slightly heavier, I didn't weigh them both, but I will tonight and report back. The fuel weight would be similar because I would keep the Jato tank half full, whereas the Sullivan I was keeping closer to full since 1oz of fuel goes pretty dang fast.

For a split second there I thought that said "I tasted the mix..." I was like "Uhhhh someone better check on Johnny!"

Haha, well nitro is running in my veins according to some as it is, so

 

[johnnydmd]

Sigh. Radio still cutting out. I'm thinking it's the transmitter. I do have a spare, but I didn't have it with me of course. Cannot really gauge my data since it's at around 100ft it loses it most times. You can see it in the acceleration graph where the throttle spring closes the carb all the way - and it probably starts closing at the 2 second mark. I also shook the tires at around the .7 second mark - I didn't bring tire sauce with me - I had my wife with me and we only had about 15 minutes to work with here before I got in trouble

The tank does work well though, I have the LSN and idle pretty solid, still running rich I think I can lean this out quite a bit yet. With limited time I didn't want to take the body off and start messing with the tune. I did get my wife to video a 60 ft launch (by now I was afraid of another full run with the thing losing radio and veering off into a curb or something. This wasn't my best launch, kinda half throttled it the first couple of feet and then mashed it, then quickly let off at 60 feet.

I've swapped transmitters last night, so I'll hopefully run out there this evening or early tomorrow morning to test. If that doesn't work, I'll use my Spectrum DX5. Only two days for a race, so I'm running out of time, not to mention I'm still getting MeatETR sorted out - though I think it's pretty much ready.