Top speed with 40 tooth spur and close ratio gears?

[dh3.3]

Does anyone know the top speed of a revo 3.3 with a 40 tooth spur gear and the close ratio gears (part # 5383) for the tranny? I like bottom end but I don't want to lose to much top speed.

[Double G]

You could to 40T spur and wide ratio.

[Rock0utRC]

With mine I didn't notice to much of a drop in top speed with the 40 tooth.
The 40tooth spur gear's only like 3 bucks. You can try it cheap and if you don't like it you can toss the 38 back in it =].
My Revo has a 14tooth clutch bell with 40 tooth spur gear lol It takes off like crazy. That was the only time I saw a huge difference in the take off. Then just played with when 2nd gear engaged.

[Krunch]

I have 14/40 with close gear ratio...25-30 with my gps mounted....15/38 wide I was getting 42 mph. I prefer the 14/40 close= yeah buddy!!

[dh3.3]

Thanks a lot guys! I think i will go with the 14/40 and keep the stock tranny gearing.

[NITR0 newbie]

I have run all combo's from 14/40 to 16/36 on both my 3.3 and my 2.5r.
The 3.3 with stock trans gears and a 16/40 is the best all around set up for me "BASHING".
And the 2.5 really likes the 15/40 set up with the close ratio.
Fact is there are so many ways to set up and tune that it is mostly personal preference that will prevail.

[Rock0utRC]

I have run all combo's from 14/40 to 16/36 on both my 3.3 and my 2.5r.
The 3.3 with stock trans gears and a 16/40 is the best all around set up for me "BASHING".
And the 2.5 really likes the 15/40 set up with the close ratio.
Fact is there are so many ways to set up and tune that it is mostly personal preference that will prevail.

Lol I agree! oh for the 14tooth clutch bell you also need the smaller bearings to fit the stock 15tooth bearings wont fit.

5214 Clutch bell (14-tooth)/5x8x0.5mm fiber washer (2)/ 5mm eclip (requires 5x10x4mm ball bearings part #4609) (1.0 metric pitch)

[kgombe1]

14/40 with standard gear ration.. is just the best all around.... if you racing you always want close ratio.. and play with sb/spur combo.. but for bashing each his own on that..

the reason why i prefer close ratio is that it gives you a seamless shift and keeps the engine in higher part of its power band.. so not much loss it power with shift..

[Revo gene]

I am running 15/40 with stock 3.3, ERCM pipe, and Buku clutch.....gps reads 51.8mph with stock trans. On the picco .26 I run 18/36, Buku clutch, side blow pipe, and wide ratio RR trans......result is 68.9mph on the gps.

[Krunch]

I am running 15/40 with stock 3.3, ERCM pipe, and Buku clutch.....gps reads 51.8mph with stock trans. On the picco .26 I run 18/36, Buku clutch, side blow pipe, and wide ratio RR trans......result is 68.9mph on the gps.

Sweet!! I got to get me a ERCM w/buku clutch on my stock 3.3.

[lubecakes]

There's no way you're hitting 69 mph with a nitro revo.

[Double G]

There's no way you're hitting 69 mph with a nitro revo.

I think Over_revO did. I'm searching for his videos on Youtube.

[lubecakes]

It probably has been done, but not easily. I have an 18/36 ratio with wide gears and a sirio s27, but can't break 50 mph.

[Revo gene]

Lube - gps confirms my runs. iMO it is a combination of the clutch, header, pipe that are giving me higher speeds. I'll try to video a run tomorrow with the gps and post. I want to try gearing it with 18-40 but, I can't find a mount to allow for it.

The clutch allows me to really tune the clutch and lock it in at high RPM's. The exhaust allows for alot more flow allowing much higher rates of fuel.

BTW: I have seen even higher speeds from others revo's on here.

[kgombe1]

I'm with lube on this one.. one guy did get 72 MPH but that was with a Modded 28XZ.. (which is waaaaaaaaaay more powerful than the picco) .. he also ran the slayer trans .. which gives him a taller ratio than the wide.. and he ran 18/36.. so i don't see you hitting 69 with that setup..

sorry.. kind of hard to believe

[Oomp]

On the picco .26 I run 18/36, Buku clutch, side blow pipe, and wide ratio RR trans......result is 68.9mph on the gps.

That drivetrain gives you a final drive ratio of 12.01:1. If your engine hit 35,000 RPM, you would only run about 49 MPH.

The Slayer drivetrain, with Revo sized tires, would run about 77 MPH.

5.6" diameter tires x 50,000 RPM's = 69.35 MPH. The Picco is not hitting 50,000 RPM's no matter what clutch, header or pipe is used.


1. Measure the outside circumference of a tire
2. Divide the engine RPM by the final gear ratio (this gives you the wheel speed)
3. Multiply the tire circumference by the wheel speed
4. Divide the result by 12 (This is the number of feet traveled in one minute)
5. Multiply by 60 to determine the feet traveled per hour
6. Divide the feet traveled per hour by 5,280 to determine the miles per hour traveled

[kgombe1]

you had to bring the math in huh.. LOL.. i have a excel sheet that does it

[Revo gene]

the math makes perfect sense and numbers dont lie. I'll measure the setup and run it through this and see how far off things are. I agree, noway in the world the motor would even reach 50,000 rpm's much less stay together. I am using a GPS feature on my Iphone to record the speeds so I would assume now that might not be accurate. I could ask a local cop to laser it I guess, but around here, they would probably issue me a ticket! LOL

I'll post results later tonight.

[Revo gene]

Can you email me that spreadsheet you have?

[lubecakes]

You could just use the gps in your car to calibrate it or determine roughly how far it's off.

[Oomp]

I figured mine out, and it made me laugh.

I run an OS 18tz, with either 15/38 or 15/40, with the standard ratio 2nd gear set, locked in 2nd. I used 30,000 for my RPM. My top speeds are 30.23 mph and 28.72 mph, respectfully (if I can be so bold, LOL). Although that may seem goofy, and it did to me when I figured it out, we only raced our Revo at our local track. The track is usually technical, and you are on/off the throttle a lot. And with 15/38, we run the same Final Drive Ratio as your typical truggy (16.54:1).

[twisted metal]

I'm not sure what you guys are doing to your revos but I also run the tz with 14/40 and I know for a fact it doesn't run 28-30 mph, more like 37-39 depends on mainly on were I run at. And I can tell I turns anywhere from 39050 to 41075 rpms under full load at wop

[lubecakes]

from 39050 to 41075 rpms under full load at wop

Oomp said he figured his at 30,000 rpm, so he probably is approaching 35-40 mph.

[Oomp]

I am only giving you the theoretical math. I understand momentum, tire expansion, uphill/downhill, etc, all comes into play. But how far do we want to go in figuring out MPH? It's not that important. Well, to me it isn't. I am not running my truck up and down the street to see how fast it goes. It's nice to have an understanding of the math though, and how much gearing affects the performance of the truck.

Thank you lubecakes. I simply went onto OS's web site and used their advertised "2.28 HP at 30500 RPM" as my reference. Figured that was only fair. They show the practical RPM range as going up to 34,000 RPM. Again, I set up my truck to race (yes, it is just sitting there gathering dust now). I only need to get from point A to point B as quickly as possible, then turn, and do it again.

But, twisted metal, I would like to know how you came up with 39,050 to 41,075 RPM? You run 14/40, but with what 2nd gear set?

[twisted metal]

as for the gear set i run the wide ratio set up with 14/40. And the rpms I do alot with dynos and and tachometers buliding NTPA pulling tractor engines. I have bulit a dyno nothing speacial just big enough to goof off with rc cars, thats where i came up with the 39,050 to 41,075 engine rpms, and another food for thought the tz produces 2.68 hp and a massive 38 ft lbs of torque LOL at 40,000 even with that set up, and the equiv. drag of the weight of the truck. The rpm ranges on the o.s website or any other for that fact is as you said "practical". That doesnt mean the engine cant turn more than that.

[kgombe1]

Can you email me that spreadsheet you have?

pm me your email

[Oomp]

massive 38 ft lbs of torque

That right there is pretty awesome. The TZ is my favorite engine in the Revo.

[twisted metal]

yea I wasn't trying to be a blank... Just stuff I had proven accurately, and though you guys might like to no

[dh3.3]

I am running the 14/40 with standard ratio now, and I love it! Huge wheelies and amazing torque!

[Oomp]

I am running the 14/40 with standard ratio now, and I love it! Huge wheelies and amazing torque!

Awesome. Glad to see you found your setup.

yea I wasn't trying to be a blank

Well, you were holding out on us you blankety blank. LOL. RC Dyno's arent a dime a dozen ya know. They have been discussed for years, but the concensus was they didnt exist. I made my own pipe for the TZ, and always wondered how to compare it to the stock pipes performance. I also have run the TZ in my kids 1/8 scale buggy, and purchased the OS pipe recommended for the engine. I made a side exhaust version of my pipe for the buggy too. I can see that the power comes on a little sooner with my pipe, but I always wondered if I could actually figure out how much power each setup makes.

[twisted metal]

I've been a hard core o.s man for several years now, have you had any premature bearing failures with the tz? I've always heard they were bearing eaters and my tz ate its first set a few days ago with only about 8 or 9 gallons on it

[kgombe1]

only 8 or 9 gallons.. really.. thats a lot of fuel.. my TZ's never went through bearings before its time.. that being said i usually run 8 MAX gallons through my race engines then its time for another...

[lubecakes]

Yeah, that's a crap-ton of fuel on one set of bearings. Figure an average of 30,000 rpm for 10 minutes each tank multiplied by 25-30 tanks per gallon.....That's roughly 65-70 MILLION revolutions at 9 gallons. I wouldn't be complaining lol.

[twisted metal]

haha im not really complaining, its just odd to me because ive always gotten around 12 to 14 gals outta my tm's and when i went to the tz ive seen several post on other forums about them being bearing eaters, and at 8 or 9 gals thats just earlier than and problems out of my previous o.s engines.