Possible (slightly) future project with Toyan engine.

[johnnydmd]

The all new Cison V8's are officially on sale (pre-order).

V8 Testing

They seem vastly better than the Toyan V8's, but the promises of the cost were greatly exaggerated. Looks like they are going to be around 2k. Pity. Can't say I have any interest at this point, not at that price.

 

[easy rider]

Man, this is so cool. There are some talented people on this site.


After seeing some of these cars, I’ll never post another pic on the rig of the month thread. It’s just amazing to think a person could build such a cool rc car.

 

[johnnydmd]

Still waiting for reviews on the Cison that are more concrete (as well as better pricing). I've seen numerous videos of JohnnQ90's car, and he seems to be slowly evolving what he's doing. He at least has it functioning, but it's not exactly fast. Seems he recognizes why (that the gear ratios were too low). Still, I'm not sure making a car that could go 10 mph to 15 or so is making me think it's worthwhile. That Toyan engine doesn't sound very strong either.

I did at least see with the Cison engine there is a clutch for it, that looks like it can accept 1/8th scale bells. That's a big plus. That, along with JQ90's trials and tribulations made me re-think a bunch of stuff in my (fantasy, for now) build. I think I'd go with a 3 speed Kyosho transmission and set it up to be able to really tweak the final gear ratios with using some various pinion gears. With the Kyosho gears, it uses a roughtly 4:1 sprocket/chain system to really gear the thing down in the Mad series. I'm thinking if that ratio is made closer to 1:1, then an engine that revs say 11k rpm would be able to hit top speeds that would be more acceptable. It would even be possible to gear it way up, maybe even say 1:1.5 or something like that.

I've been passively thinking about it for months, and keeping track of my ideas in a diagram that is a rough layout:

This is a smaller car than what JQ90 built (his is 500mm wb, this would be 410mm). I think his is a little too big and heavy. Mine would be mostly CF.

 

[johnnydmd]

I re-designed my concept. Cison does make an output d-shaft that you can easily bolt on different gears. It makes sense to me now to revamp the transmission concept so that I can use better clutches than what they offer (which in no way I think are strong enough). With the new design, I can use 3-4 shoe 1/8th scale. If that doesn't hold, I could make a custom bell, or possibly use a 1/5th scale setup, as the bell and clutch would be on their own shaft that would have a d-cut on the end to accommodate a set-screw gear. This way I can play around with FDR's to no end as well by swapping gears on the engine output shaft and the clutch shaft.

I'll need to get a custom shaft for the clutch/bell setup. I'm contemplating a mini-lathe, well I really want one anyway for so many reasons. I was looking at this one:
https://www.amazon.com/VEVOR-x14-Benchtop-Variable-Precision/dp/B09FDVMYXS

Not sure, but I think it'll be fine for making small shafts and stuff.

I did a bunch of math, based on the top speed of the Kyosho Mad Crusher (40mph) from which the transmission came from. Assuming the diff ratios would be similar using Savage diffs, and based on the KE25 rpm limit of 33k, the Cison is 11k, the Mad Crusher using 2.5:1 reduction with the chain/sprocket setup, the car would have a top speed of 33mph if I had a 1:1 ratio between the engine and trans. To get this where I'd want it, probably need to do about 1:2.5 ratio, giving it a top speed of 83mph, which would be decent for a 1/7 car. Maybe 1:3 would be best even.

I have yet to see the engine in a vehicle, but I do know a few are working on it. I'm kinda hoping JohnnQ90 swaps his Toyan out for the Cison (he has both the OHV and Flathead versions already) so we could all compare. There is no doubt from the reviews coming in that the Cison is a vastly better engine, with far greater throttle response and power. It's advertised at just under 5hp. I'd really need to keep the car under 15lbs to make it comparable to my nitro cars. Really, around 12. Possible? The engine weighs 5.5 lbs by itself. Radiator .17 lbs, and so I'm thinking let's go with about 6lbs of engine/radiator, tubing, mount, etc. I believe my current 1/8th scale rolling chassis weighs 3.5 lbs without the engine/exhaust. Call it 4. This chassis would be longer, a bit wider, I think though at most, half a pound more of CF. I'd still run 2.5 on the bottom, 2.0 on the top plate. Let's say 5 lbs then to be on the safe side. Then it's just the difference in weight between the trans/diff combo and the alloy Jato trans. That would be at most half a pound, if even a quarter. I think 12 lbs might be realistic actually, including likely heavier wheels/tires. This gives it a power to weight ratio of .4 compared to .5 for my big block nitro car. To achieve the same PWR I'd honestly have to get the car to 9.6 lbs.

Maybe that's not a huge deal. The V8 would have vastly more torque than a single cylinder 2 stroke. That said, it would be a pretty mean feat to get the thing under 10 lbs. I'd still use a Jato fuel tank, so that'd be equal there. What would help is finding lightweight wheels/tires. Right now, there are very limited options for this scale, and virtually zero drag options. I'd be using some shaved down ProLine Menace belted MT tires for the rear, and DT Banditos for the front.

Then, there's the options of power adders, a whole territory that is only being explored right now with these mini V8's. Turbos. Nitrous. It's all being done as I write. That would of course really change the equation and who knows how much.

I'm still tepid on this whole thing, but I really cannot stop thinking about it. I think what I'm going to do is 3D print the engine, radiator, various parts I don't have, to prototype it out. I do already have pretty much every other part already. I have the trans, bell, clutch, fuel tank, arms front and rear, shafts, brake, etc. Maybe I'll grab a body and prototype the entire thing over the Fall/Winter. I see the Cison V8 is dropping in price some too with some discounts/specials. There are some other V8's on the way in the same scale from what I'm hearing too. I think I'll have a roller that I can drop whatever powerplant in I want.

Of course I did think of a name/livery if I somehow pull it off...

 

[Greywolf74]

I love this build!

 

[johnnydmd]

Another thing I thought of, is I should do a 4-link solid axle rear using a cut down Kyosho Mad Force axle - which I just happen to have I have a set of super beefy Savage gears that fit right in it too.

This wouldn't be hard to do in 3mm CF and some bracing.

 

[WickedFog]

Another thing I thought of, is I should do a 4-link solid axle rear using a cut down Kyosho Mad Force axle - which I just happen to have I have a set of super beefy Savage gears that fit right in it too.

View attachment 203585

This wouldn't be hard to do in 3mm CF and some bracing.

Oh yeah! That would be sweet! Just think of the tuning possibilities. And the scale look of it will be awesome if you can see it under the car.

 

[johnnydmd]

I revamped the livery some after some constructive criticism from da wife. Little cleaner and meaner.

I've been 3D printing a replica of the engine over the past couple of days so that I can start mocking things up. I have a 1/7th scale VPR body coming tomorrow. I contemplated using the 1/7th Dodge Demon body too...I am a Mopar guy, so it was either that or a Viper.

Going to route the exhaust out of the side and use CF plates bolted to the body as a guide/buffer for the tips. Probably use some rubber to line the hole in the CF to get rid of rattle.

 

[CertifiedMike]

Mopar or no car Baby!!!
This build is next level insanity/awesomeness!!!
I can't wait to see what's next!

 

[johnnydmd]

ScaleMonkey makes some pretty dope sidepipes that hopefully are exactly the right length (If not I'll mod them).

 

[Lukedavis]

watching!

 

[johnnydmd]

Litte more updating of the design doc. I have the engine printed out as well as the body and rear wheels/tires. I think this weekend since it's going to rain the entire time, I'll spend some time mocking some stuff up and printing out prototypes. I've got some thin plywood scrap to use as a lower chassis plate test, and I can start seeing what fits. I think the Scalemonkey headers might be perfect, but they are awfully expensive, so I might just make my own sidepipes.

I was really thinking about that clutch too. So, I've got a 1/8th nitro clutch in my nearly 20lb monster truck that is running a Force .38 which is probably not a lot less power than the V8, at least peak anyway. Obviously low end the V8 blows it away. But that clutch hooks hard and never slips. I was wondering why JQ90 had problems with his, and then it dawned on me that using stock springs could have been the problem. The V8's are much lower RPM, those springs are designed for something 3x the RPM. Putting on some much lighter springs might do the trick - probably even springs from a 1/10th shoe would work if they'll fit.

I will probably also make a replica of the 3gear clutch bell that has no clutch (shouldn't be hard to do, just put some gears on a d-shaft), so that I can stick my .38 in there as a benchmark and make comparisons.

 

[CertifiedMike]

The springs sound like a great idea! It sounds like you might have that worked out! One down!