Hissed Off - Nitro SE Drag Car

[kdecesari]

Nearly done with the body.
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Wound up slapping nitrous in this thing

New shocks on the way. Weighed the car, it's at 4.99 lbs, so down from 5.5 or 5.6 lbs last season.
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@johnnydmd your build is looking sweet.
Drag racing isn’t on my radar & I don’t know anything about the work you’ve completed. That is probably why I am in awe of your machine.

You trimmed a lot of weight off it. How do you go about managing weight balance with one of these? Honest question. Just curious.

Good luck this season!

 

[johnnydmd]

@johnnydmd your build is looking sweet.
Drag racing isn’t on my radar & I don’t know anything about the work you’ve completed. That is probably why I am in awe of your machine.

You trimmed a lot of weight off it. How do you go about managing weight balance with one of these? Honest question. Just curious.

Good luck this season!

Thanks!

I use a corner weight system to get precise measurements. Getting it really balanced isn't easy. I'm mostly concerned about front-rear, and the rear corners. Generally the nitro builds are pretty even in the rear. The area they aren't great in is front-rear. For that, I like to put the receiver battery up front, and add aluminum parts in the front like bulkheads, arms, shock towers, where needed. Since this car was really light, I kept the alloy shock towers, and put an alloy bulkhead on the front. It's balanced at 38% front, 52% rear, which is decent.

There are things I could replace to lighten it (bulkhead, shock towers), but I need to test first. I'm probably getting pretty close to the point where it's too light, especially for dry tire runs.

 

[johnnydmd]

I got my new shocks, and these things are sweet. Say what you will about Integy, but I have found that their shocks are very well made and hold up great, never had them leak.

These are a decent bit lighter than the previous monster sized things I had on there. Had to shorten the travel on the rears by 10mm as per usual with drag cars to get the arms level. The dampening is now vastly smoother.

I have new aluminum steering/camber links coming to replace the heavy stainless ones. Also, they are way easier to adjust. (Same as the ones I have on Invader 2).

Not done. Nope. Something I had been pondering was just splurging and getting a high-end .12 like an OS Speed 1204 but couldn't justify spending 600 dollars. However, I found them being sold at 385 at Absolute Hobbies, so I pounced on it. I'm going from a 54/24 setup with the OS .21 tm to a 65/20 setup with this one since it's got way more top end. I generally don't subscribe to manufacturer power ratings, but when it's across their product line I would think it's a decent barometer. The T1204 makes the same power as the OS .21 tm (1.7). So, I think this should allow me to gear the thing up and get insane 0-60 action but still have just as much on the top end since it goes to 45k vs 35k. It'll be fun to try both setups actually. Engine is 50gs lighter than the .21 tm as well.

Since in 2024 nitro drag racing is continuing to grow rapidly, a lot of events are separating big and small block cars. I've already got the big block setup about as far as I could take it, so getting this one up to par was a no brainer. There are a lot of veteran racers down south that are swearing that these tweaked out .12 engines are outrunning anything and everything, so I figured I'd at least have to try and see. Just can't beat the price for that quality of an engine.

 

[Doom!]

I got my new shocks, and these things are sweet. Say what you will about Integy, but I have found that their shocks are very well made and hold up great, never had them leak.

View attachment 179848

These are a decent bit lighter than the previous monster sized things I had on there. Had to shorten the travel on the rears by 10mm as per usual with drag cars to get the arms level. The dampening is now vastly smoother.

I have new aluminum steering/camber links coming to replace the heavy stainless ones. Also, they are way easier to adjust. (Same as the ones I have on Invader 2).

Not done. Nope. Something I had been pondering was just splurging and getting a high-end .12 like an OS Speed 1204 but couldn't justify spending 600 dollars. However, I found them being sold at 385 at Absolute Hobbies, so I pounced on it. I'm going from a 54/24 setup with the OS .21 tm to a 65/20 setup with this one since it's got way more top end. I generally don't subscribe to manufacturer power ratings, but when it's across their product line I would think it's a decent barometer. The T1204 makes the same power as the OS .21 tm (1.7). So, I think this should allow me to gear the thing up and get insane 0-60 action but still have just as much on the top end since it goes to 45k vs 35k. It'll be fun to try both setups actually. Engine is 50gs lighter than the .21 tm as well.

Since in 2024 nitro drag racing is continuing to grow rapidly, a lot of events are separating big and small block cars. I've already got the big block setup about as far as I could take it, so getting this one up to par was a no brainer. There are a lot of veteran racers down south that are swearing that these tweaked out .12 engines are outrunning anything and everything, so I figured I'd at least have to try and see. Just can't beat the price for that quality of an engine.

Nice score, Can't wait to see how she does with the new power setup.

 

[johnnydmd]

Got the T1204 in. PITA. Just cannot understand why engine manufacturers are not consistent with their drive shaft lengths. A little shimming at least got the spur off of the bell housing, but I'm only able to get about 2/3 of a mesh alignment. The issue is that the threading on the shaft is too far out (and the shaft is a good bit longer than the .21 tm), so the bell sits off the flywheel too far (about 1.5mm too far). I shimmed the spur about .5mm (that's as far as I can go with that and not compromise anything). Tried a few slippers and none of it helped. The real solution to this will be replacing the 5x11x4 inner bell bearing with a 5x11x3 which I ordered from Boca this morning. That should get it lined up pretty close to 100% and keep the bell from wearing out too fast.

No need to cut the head down, it's already tiny, and far too pretty to mess with These little .12's heat up quickly from my experience with the .12 tg I have.

I put on the THS header and pipe for now and I have an opportunity to break the engine in saturday, we got a 2 day warm spell. I have another pipe/header combo coming to try out that's made for the engine specifically. May the best win.

Replacing the mismatched green body posts with black ones. Front wheel/tire combo getting swapped out for lighter, skinnier stuff. Have some really nice rear camber links on the way that will stay tuned better. That *should* wrap up this car for 2024.

Body is also finished now.

Will just need to lock some of the nuts holding things on, etc. Otherwise, it's good to go.

Re-weighed the car. It's now 5.15 lbs. Realized when I weighed it last time it didn't have the engine guts and clutch/bell on it, so that 4.99 was a little misleading. I'm good with that weight though, it was 5.59 last season. The new front wheel tire combo should drop it closer to 5.0 I think. I could also swap out the shock towers to CF if I need to, but I also don't want to get it too light. Balance is pretty good overall.

 

[ahr43]

Looking good, Johnny. Real good. How many ports on the new .21 compared to the previous engine?

For what it's worth, my rails settled in at 40/60 F/R weight ratio for best traction/handling compromise. Always carried 1 or 2oz FR ballast to get that figure. So thinking you're close on F/R balance.

Sounds like 2024 gonna be a dog fight at the track with all the builds going on. 'AC'

 

[johnnydmd]

Looking good, Johnny. Real good. How many ports on the new .21 compared to the previous engine?

This new engine is a .12, so I'm dropping down in size from the .21 in fact. The .21 has 5 ports, the .12 has 3 (I think that's the case for all .12 engines). OS rates the .21 tm at 1.77 hp, and the T1204 at 1.73 hp, so very similar in power, but the T1204 can go to 45k vs 35k for the .21 tm. That was the main reason to try this engine, I am looking to increase the top end power. The car was very quick to 60 ft, probably even more than my big block car, but from day one (going way back to 2021 when I first started using it that engine competitively) it would get run down on the big end. Granted the early days it was another car, transmission, and chassis, but the problem persisted with this build too. I've been watching the down south guys racing a lot this year, and the really fast guys were swearing about the .12 engines and gearing them up to get crazy fast times. All in all, it's just taking a different approach than Invader 2, where I'm going mountain-motor with low gearing (18-40 mod1).

So, I will try out that 20t bell first, which should make up for any torque loss (though I keep hearing this engine has a lot of it) on the low end, and the engine will eat on the big end. I hope anyway. And yeah, the competition this year will be fierce on our team alone.

I'm replacing the rear arms with stock ones too. Those STRC ones are really heavy.

 

[ahr43]

Thanks for sorting out the .12 vice .21 for me. Now I get it. Yeah, three ports "generally" have tons of torque compared to 5 or 7 port engines - at least in my limited nitro experience. That said, sounds like the new .12 install will work out well.

Recalling my drag racing days watching the nitro cars run. The .18 'Top Alcohol' class was always competitive in time and top end with the .21 'Top Fuel' class. In fact, it was not unusual for a .18 to take top time of the meet on more than one occasion. Curious now to hear how this .12 runs out. Yeah, sounds like you can give up some 60ft time/speed for more top end. Hope it meets your expectations for a competitive package.

Cheers. 'AC'

 

[johnnydmd]

Got the break-in started. Eventually got it out in the driveway doing some little short bursts. Power feels good so far. Sounds really nice. Got my new header and pipe coming today, so next time I'll run it with that.

Replaced the rear arms with plastic and re-weighed. Down to 5.1 on the nose. The new front wheel/tire combo comes today, which will drop it down real close to 5.0 or so.

Slick new rear camber links coming tomorrow - they are locking so it'll hold better than the standard type that tend to get off if stressed (guessing the threads pull out of the plastic rod ends sometimes?). Actually, got a set for Invader 2 as well for this reason.

I have a 20t bell in, but I have an 18t bell coming that I do want to try out. The 18t would make it a 3.0 ratio, which is pretty high compared to what it originally was with the 24t (2.25). 20t is 2.7 on the nose. So, if the engine rpm is 45k vs 35k with the .21 tm, the RPM vs GR would be 1.28 originally with the .21 tm. The T1204 with a 20t would be 1.2, and with the 18t would be 1.33, so this should be interesting to see which bell has better times. I felt before that the car was lacking on the top end, so it's possible the 20t is the better choice.

 

[Doom!]

@johnnydmd I know nothing about nitro yet still find your updates very interesting. Always look forward to them.

 

[johnnydmd]

Well, it's done Other than I have another pipe and clutch bell coming in that I will test out vs the stuff in there now. I got the ProLine Frontrunners for the front, and used a chrome pen to make them look alloy, and put some white lettering on the tires. This wound up shaving it down to 3307 gs in weight, so just over 5 lbs. I could still swap the alloy towers for CF but I'm thinking it's good to go at this weight. I've seen vids of the T1204 in SC trucks doing wheelies in dirt, so any lighter might be tempting fate (and traction).

I'm hoping next weekend might be some warm, dry weather and I can take it out and play with it some. If not, I'll tear the engine down and put it away until Spring.

 

[Doom!]

Your latest enhancement really helps an otherwise bland looking car.

The rims and tires look great, added a nice bit of detail. Your going to kill it this season if she performs half as good as she looks.

 

[johnnydmd]

We had temps close to 50 both days this weekend, so I packed up the car and took it to my favorite practice spot to finish the break-in. Used an engine warmer to keep the engine temps up. Saturday the engine was still tight as hell (very typical of every OS engine I've ever owned). It was stalling at TDC a few times until I got it hotter and looser. I was running the 20/54 gearing. Eventually after a few more tanks of running around a little harder, I started making 132 ft passes and tuning some. It seemed "ok". No where near the power of the OS .21 tm I took out of it (which I also had with me planted in Incinerator for some comparison since the two cars are similar weights). Pretty sluggish out of the hole really, but it did wind up pretty high. Some of this is obviously the engine still being super tight.

I did about 20 passes, and it felt like by the end it was getting a little faster. Even hot, I could not turn the engine past TDC with my fingers. So still extremely tight.

Sunday, I came back. Same conditions, upper 40's near 50. Kept the engine heater over the engine to keep it hot while I made a bunch more passes. Tried some more tuning, but the tightness of the engine was still holding it back.

One thing that was seemingly positive was that all the chassis changes worked great, the car was hooking up and going straight as an arrow (though the lack of power certainly helped). I decided to try some different gearing too. Went to a 56t spur first. Couldn't tell much difference really. Then went to a 58t. Immediately realized I needed to stiffen the rear springs some, and add some bump stops in the shocks as the gear was hitting the rear arm. Tires were rubbing the body at points as well, so these changes fixed both of those issues perfectly. Seemed a little snappier now. I had a lot of clutch bell choices to try.

Sadly, I could not try the 18t bell as it uses smaller bearings (learn something new every day). I made a bunch of passes with the 20/58 setup. It was a bit quicker it seemed, but still, not really as good as expected. Man, this engine was still tight as a tick. I figure I'm going to have to spend every single warm day I can with this car and running the snot out of it until it loosens up.

Finally, I decided to do some passes using nitrous. I was a little scared to do that with the engine so tight, wasn't sure exactly what might happen. Also, not really sure how this system was going to play out with a much smaller engine that I've tested before. I figured the effect would probably be a bit more dramatic than in a .30 sized engine. I was right! I hit the button 10 feet out, and the car literally exploded in power. It just about tore the tires off. (In fact, inspection showed some rather frayed tires after the hit). Well, that was pretty addicting! So, I did another pass. Same thing. Wow this thing might actually be pretty fast. Set up my phone and recorded a third pass. Again, hitting the bottle at the 10 ft mark.

The launch is still pretty soft, but you can see/hear from the video where I hit the bottle. I'll work on the launch some. I think getting the engine looser will clearly help with low end power, but I also have a new, high torque pipe coming, and the 18t bell to try. I also need to work on the clutch, it definitely engages too soon.

 

[johnnydmd]

I finally had a "semi" warm day to test (48 deg). I had the 18/58 setup and the new Team Orion pipe installed.

Did some all-motor passes first, and these changes combined with the motor getting a little looser (I recently learned that this particular engine is a MF to break in apparently according to many) - the launches were noticeably quicker and, well, harsher. Now the car was getting a little squirrelly on the bottom end - though nothing compared to Vegrant and Incinerator. Not yet anyway. It was definitely more predictable than those two cars with their higher torque, low gearing setups.

I decided to put the body on and charge the nitrous system for a real pass. Little risky on a day this chilly. This was made easier by my new routing of the charge point and pressure gauge changes I'd done earlier in the week.

As before, the car really exploded in power when I hit the button, and it got all kinds of sideways. But wow, the car was ridiculously fast - much more power than the video in my previous post. I went to try again, and this time it felt a little weird, and it didn't shift into second gear. That seemed weird, so I started tweaking the shift point some, and still couldn't get it to shift. I noticed something else seemed a little off too, a little hitch in the gears. Took it home and tore the transmission down.

It was pretty much demolished inside. Looks like the 2nd gear clutch bell blew apart and bits got jammed in main/diff gears and shredded them too.

My best guess is that running a slipper eliminator is just a no-go with plastic gears. That's the second time I've used the thing and torched a transmission like that. Well, it's easy to see why 2nd gear wouldn't engage anyway, lol. Looks like both metal catch posts broke, and one got loose and ate the diff a bit. I had spares, so I rebuilt the thing and put in a slipper clutch. Next round of testing will determine if I need to take other steps, next of which would be to replace the bell with an HR steel one. Hoping to not add that rotating mass to the drivetrain, but it's not a huge increase I suppose.

 

[ahr43]

Looking good.

Track temp and tires being cold may have contributed to the squirrely action. Perhaps she'll track better on a warmer test day (soon to come, fingers crossed).

Yeah, adding rotating mass always sems to come with increased durability. Tough to get one without the other. Or perhaps, better said, tough to get one without the other affordably.

 

[Doom!]

Sucks you blew the tranny, not to be taken out of context thank you.

 

[luke66]

Burnt tranny. No good

That Viper body tho. Very good.

 

[johnnydmd]

64 degrees on Sunday, so I took the car and spent a couple of hours testing and getting the shift point dialed in. earlier in the morning I swapped out the (very) heavy Integy shock towers for CF. That was a 70g weight drop. I didn't weigh the car, but based on last time, that puts it under 5 lbs at 4.95 or so.

Aside from the nitrous system (which is 85g) there's not much else I can do to lighten the car, and after testing it's clear I wouldn't want to. This was also my first real testing with the new pipe and gearing, as last time was with the broken transmission. Got myself set up, marked off a spot to keep the local driving instructor from cutting through my lane as he keeps doing this year. (C'mon man, it's a huge lot, and I'm off to the side, so give me some courtesy!).

I spent the better part of an hour or more trying to find the shift point. Those Jato transmissions are pretty sensitive with that. So, I did a number of passes with the body off. The T1204 is starting to make a lot of power too. Giving it anything more than 1/2 throttle sent it spinning out of control. Eventually I found the shift point and slapped the body on for some "real" passes.

Having the body on made a huge difference. The downforce kept the tires much more planted, and I got some pretty good all-motor hits in. Then I moved on to doing some nitrous passes. First pass was dead on perfect. Set up the camera, made another similar pass. Called it a day - the car will sit until the season starts in 3 weeks.

I hit the nitrous at the first cone, and you can see/hear the power surge. This is definitely a real game changer. Video clock indicates that was a 2.2 second run. Not bad at all for dry tire on 64 degree day and not even giving it full throttle.

 

[Tunedfrog]

I figured this would win the contest, nice work. She looks incredible.

 

[johnnydmd]

I figured this would win the contest, nice work. She looks incredible.

Well, I'm glad it won now, because it will not look nearly as good in a month or so