RCU Forums - View Single Post - Nasty 1/10 scale on-road cars using .21 or larger engines....come inside
Old 01-02-2009, 11:24 AM
  #293  
nitrorevo
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Default RE: Nasty 1/10 scale on-road cars using .21 or larger engines....come inside


ORIGINAL: Over_revO


ORIGINAL: Brent Davis


ORIGINAL: nitrohead5300

I was just looking at the tower site, motor section a OS .12TZ Speed weights 7:33 oz at $400.00 plus dollars a pop a OS.18TZ weights 7.8 oz at $150.00 a pop . OS .18 tz only slightly heavier and a savings of $250.00 which I could used to have the OS .18 TZ extremely modified drop it in my V-1RRR and have the perfect high speed road racer . The guy I want to mod this motor AB Mods modified a .12 that was put in a Nitro TC-3 that beat a Big Block .28 Fusion in the Worlds Fastest RC Car Challenge ( US edition) The Nitro TC-3 with this .12 was propelled to 79mph.

Yeah that ABmodded .12 was a beast against those bigger motors no matter how well the gearing and cars were tuned for the motor, it did that speed with a .12 sized engine[X(]. Makes me wonder what in the heck was that guy thinking after getting beat by a .12.

While I am not a small block type of guy, I will see how well this .18 TZ is going to do but again, I just can't see how a comparable ABmods .18 TZ could run slower than it's counterpart ABmodded .12 TZ and both in the same chassis, same day, same fuel, etc. I am saying this based off ppl that said a .12 or .15 will run the same MPH as a .21 would with the same gearing but of course just how much quicker would the .21 get to it's top speed over the smaller engines but yet all run the same speeds....I'm not getting it.
If i understand your question right, heres an answer.. :

To a given speed lets say 75 mph, and lets say you need 1.1hp to get to that speed in a given car..
And also lets say (lot of lets say..lol) that it is geared to get 35000rpm at 75.

The peak power of the .12TZ is probably in that area and is higher than the .18 TZ@35000, the .18TZ do have more peak power , but lower, the .12TZ may hold its peak longer in the powerband...




As a real example, during my testing of the ABmods drag modified OS28 vs my Picco .21 P9R ABmods stage 2

The OS have more peak hp and more peak torque than the Picco .21 P9R (2.51hp/91oz-in vs 2.35hp/70 oz-in)
but the peak of the OS28 is 28000 and the Picco .21 P9R is 34000

In the DM1 on stock gearing, the P9R could hit 73mph no problem when the OS28 could hit 71 without problem.
At first you can think wow , the OS get spanked by the P9R. wich is true... lol

But its only because of the gearing...theres a limit as how wide of a gearing a smaller engine can handle vs a bigger one. Thats why you need to gear the car to match the powerband for the speed you want...

hope it make sense..


All those thread make me want to build a CD3


Mike,

Dude we have perfect timing bro. Always same time post.

We are on the same page. Gearing is your friend with higher torque engines. The problem is what we both have experinced in our builds is you run out of gearing. This means customizing the gears and then like I did mod the chassis to get the taller gearing to fit. After I got passed that hurdle. the next hurdle was running out of room to get the gearing to kick in. In my tests the higher rpm engine always win cause I didn't have the patience or distance. I was running 300ft when I probably needed 600ft or more with the bigger engine and taller gears.

With the higher RPM engine you automatically get the better mid/range top end and everybody makes shorter gearing to improve the low end if necessary.

That said, I am still building a little car with a big engine. Nothing like having all that low end grunt. LOL Come on and join us Mike.

Tracey