Fangdango! V8 drag car

[CertifiedMike]

Wait!.......sharp sticks?!

I'm in!!!!

View attachment 205590

If we could find a way to mount those on an 1/8 scale monster truck...

 

[johnnydmd]

90% there. Kinda.

Except one problem. Re-reading through the manual to try and find the use for a "mystery left over part", I realized that I installed the piston rings without paying attention to the orientation of the oil scraper ring. poop. Well, off with the heads again! Probably just as well as I really did want to take the oil pan off too and do a better job with the pickup tube, I don't trust that thing not to work loose without some kind of adhesive. I'm getting pretty good at tearing this thing down and re-building it by now

 

[johnnydmd]

Really love the Cison builders group. So much stuff not in the manual that should be, like the mystery o-ring and where it goes, but also apparently the connecting rods need to have the oil journal pointed towards the camshaft as well - not mentioned in the manual. So looks like this little o-ring had some greater karmic purpose of saving me grief later on! Gonna be a PITA, but like I said I'm getting pretty adept at pulling this apart and putting it back together. Probably good practice for later when I need to rebuild stuff.

 

[Finesavageboy2]

If only I had enough money to buy one of those motors. Looks sick!

 

[WickedFog]

Sick looking little engine man!

 

[johnnydmd]

Engine is back together and nearly finished. Just have to do the plugs and wires, ignition, and wiring for the starter.

Had no left over mystery parts! Some kind of miracle Here's a pic to show perspective on how tiny this thing actually is, next to a tape measure.

Updated the design document to show where the turbos will live. I've got the files for the fittings to have them 3d printed in aluminum.

The one thing that is off here is where I show the throttle servo. That's on the driver side now. Still unsure of where or how I'll mount the brake lever/discs. I have a vague idea, but won't attempt it until everything else is in place and working.

 

[Doom!]

@johnnydmd Is there much weight difference between this motor and what you would usually run?

 

[johnnydmd]

@johnnydmd Is there much weight difference between this motor and what you would usually run?

Yes. The typical big block nitro is 12 oz (but that's not including clutch/bell, air filter, etc., so probably right at 1lb) and this engine weighs 60 oz (3.75 lbs). Power output of the nitro 2.8 hp, the V8 is 4.8 hp. Sounds inefficient - though it's a little bit apples and oranges as the V8 has a ton more bottom end torque and the nitro is all top end power. But engine PW ratio isn't the full story, because engines don't just drive down a track by themselves. A couple of my gearhead friends were debating me on this until I pointed out the PW ratios when you consider the entire car's weight - it gets interesting then.

The nitro is almost exactly at .5 hp per pounds, as the car weighs 5.6 lbs, dry weight.

This means that I would need to have the entire V8 car at 9.6 lbs to be comparable. My roughed-out prototype I weighed the chassis with transmission, axle, front end and it was I think 3.4 lbs (I can't remember, but it's in the thread). So, with the engine, that put me at roughly 7.1 lbs. I say roughly, because obviously the materials have different weights than what I am using, so let's be generous and add a pound to account for the different materials, throttle servo, gas tank, wheelie bar. That would be 8.1 lbs. Next, adding in the radiator and exhaust, let's say another 1 lb also accounting for other random things, so call it 9.1 lbs.

That gives a final PW ratio that is better than the nitro car. (.53 vs .5).

So, this means that the nitro chassis weighs about 4.6 lbs, and the V8 chassis weighs around 5.4 lbs. That does sound about right to me, at least within a half pound of error. In the end we all sort of underestimate, so it wouldn't shock me for the car to even weigh around 10 lbs. That would still put it side by side with the nitro machine.
This is all of course not factoring in power adders, which the V8 can do much more of than the nitro, not to mention that the low-end power and much broader power curve of the V8 is a huge advantage. So, adding twin turbos in a full sized V8, generally what, doubles the power output? Not much on bottom end, but the V8 already has a big advantage. Are we talking close to 10 hp then? That would drastically change the equation.

I think it may also cause me to consider changing to rear axle to aluminum for strength and some weight on the rear, and possibly a stronger driveshaft setup.

 

[CertifiedMike]

The distributor is killing me!!!

How do you time it?

The pulleys are READY for a big ol blower! Just sayin!

I'm so stoked you found the drama "extra parts" before the drama found you!

Fingers are crossed for your test fire!!!

 

[johnnydmd]

The distributor is killing me!!!

How do you time it?

Yeah, that thing is huge, lol. It's timed the same way basically as a full sized one. Markings on the harmonic balancer and a tab. Initially it's done by checking the hall sensor and spark point relative to the valve on cylinder 1. When I was a kid I'd just rotate the distributor until it was pinging and then back off till it stopped, lol.

 

[CertifiedMike]

Yeah, that thing is huge, lol. It's timed the same way basically as a full sized one. Markings on the harmonic balancer and a tab. Initially it's done by checking the hall sensor and spark point relative to the valve on cylinder 1. When I was a kid I'd just rotate the distributor until it was pinging and then back off till it stopped, lol.

Timing by ear and then locking it (almost) down in case you gotta get out and crank her back a notch to get her fired up... then put it back and light the tires in victory!
I was thinking maybe it was real like but wasn't sure how much the small parts would appreciate a hard fire with too much advance.
This thing is just too much!
Thanks so much for building it here. So fun!

 

[johnnydmd]

Engine finished, and some more parts trickled in. Chassis is arriving tomorrow

Checked clearance for the gears, and it's all good by a whisker.

Set everything up to see where things sat. Need to use different link ends on the front camber links to give me a little more clearance from the front of the engine, but otherwise it's all lining up well.

 

[WickedFog]

Dude. I have never witnessed a badder RC build.

 

[johnnydmd]

Dude. I have never witnessed a badder RC build.

Shhh you're gonna jinx it, dang thing probably won't work

Probably going to move the panhard bar to a cross link on the lower 4-links after a few 1:1 drag racers saw my build on social media and pointed out some things that work better.

 

[islandlife]

So cool! Awesome work!!

 

[paytonimusrex]

woah this thing is sick

 

[Doom!]

Everytime @johnnydmd starts a new build I get excited, then I think, "there is no way he will ever top this" then the next build comes along and SHAZAAM! He makes a liar out of me every time.

Still in awe when I see these built from the ground up. I have mostly been a tweak my RTR kinda guy so this is like some sort of Voodoo magic to me. Thanks for sharing, and the detail that you add to your posts. If I keep reading them something might accidentally stick.

 

[Xraycer]

Everytime @johnnydmd starts a new build I get excited, then I think, "there is no way he will ever top this" then the next build comes along and SHAZAAM! He makes a liar out of me every time.

Still in awe when I see these built from the ground up. I have mostly been a tweak my RTR kinda guy so this is like some sort of Voodoo magic to me. Thanks for sharing, and the detail that you add to your posts. If I keep reading them something might accidentally stick.

..

 

[johnnydmd]

Some more parts trickling on in...

The alloy transmission mounts. Only thing left with that is the steel transmission gears, which are arriving Friday.

 

[johnnydmd]

The chassis arrived! Immediately I saw they (or there was a miscommunication) got the countersinking on the main plate backwards, but in the end, it didn't matter because the only thing that wasn't symmetrical was the slots for the transmission plate, and boy I had that wrong, lol. I also must have botched the measurements I took off my prototype because the rear portion was exactly 1 inch too short. A little bit of checking, and I realized I could move the rear arches back 1 inch and it still had enough room to bolt everything up the same way. Just had to drill some new holes. The transmission plate itself was slightly off in a couple of spots. Might be able to salvage it for now, but I'll surely cut a new one myself once I have it 100% right. There was one other minor bug in the front piece, where I needed to trim to clear the a-arms.

I first worked on the main plate and front end to make sure the engine would fit as expected, and it did.

Several things were apparent right away. My front springs are too soft, and I'll need to swap them out with the heavier set. The body posts were way too short, but the radiator fits perfectly. I'll also have to work on the front steering links and put them up on the top of the servo arm. No big deals here. The engine mounted perfectly, and I had enough clearance between the pulleys and the shock tower.

Then I put the rear together. I did the cross link, and it felt stable. I also tried the panhard bar and noted that it was very stable, and that there seemed to be no real noticeable bump steer (they very slightly pull the rear). I think I'll put that back on to give it extreme stability back there.

I put the rails on, and saw that the chassis was pretty flexy, even saggy with the weight of the engine. Lucky for me I had some links I could use for braces, and that stiffened it up nicely. It was also clear that the servo sat way, way too low. I had a couple of posts left, and those were just about the right height to put the servo high up enough for the throttle linkage. I'll order another pack today to finish that, and they'll also work for the rear body mounts. After setting the body on it, I saw that if I used the 77mm dogbone, the rear wheels seemed too far back in the body, so I got a 65mm one that will set it up perfectly. (It's just a matter of adjusting the rear 4-link to pull the axle slightly closer). Still waiting on my properly colored rear links.

Tonight, I'll try to fix the transmission plate and get that mounted correctly. After that the wheelie bar and mounting the radiator.

I've been watching a lot of Dennis Dempsey videos, and now I realize I need to pull the intake manifold off and put some clamps on the water hose inside the block, or else it's possible for that to leak under pressure if it overheats, making a nice mess.