Predator 212 vs. 140cc piranha?

[Ngalinus]

Hello! I apologize if this has been discussed (I looked but didn’t see it)

I have been building an extreme off-road buggy for two and a half years now and I’m starting to think my predator 212 is reaching the end of its life. It is stock (no governor) with a mostly unrestricted exhaust and a TAV. The kart is fully independent four corner suspension and has a king of clutch mechanism that I designed to allow it to switch between one wheel and solid axle drive to allow use on and off road.

My dilemma:

I love the idea of having a four speed 140cc on this thing but it’s hard to tell whether I will lose power of gain it! Obviously the predator is 212cc but it’s only 6.5-7.5 hp vs the 140cc which I have read is 12hp. Is this true?/ has anyone tried swapping between these two setups and will it work. Your input is greatly appreciated!!

---------- Post added at 12:25 PM ---------- Previous post was at 12:20 PM ----------

I would also like to add that my question is basically whether or not the 140cc 4 speed semi auto is more powerful than a predator 212cc with a TAV

 

[Ngalinus]

Photos of the project

In second photo you can see the engine setup currently

 

[Quinc]

I would think the 140 would blow the 212 away in power. You also have an endless amount of cheap motor sprockets to get the gearing perfect. Check out the GPX 155HO and even the Piranha 190. Plannitminis.com and t-boltusa.com have a lot of info on mods, best carb to run etc

 

[Ngalinus]

Thank you very much, I just didn’t know if the gearing would compensate for the displacement but I believe you are correct. I’ll post an update if and when I do the swap

 

[Kartorbust]

You may end up having to swap out the axle sprocket. It may end up being motorcycle chain (not 100% sure).

 

[Quinc]

A couple different companies make supercharger kits for these engines too.

 

[KartFab]

I’d vote 140 because gears...

If you want to keep the 212 you can slap a mod 2 cam in there with 22mm round slide and you would exceed the hp rating of the 140.

 

[65ShelbyClone]

Frictional loss with a TAV is generally accepted to be 20-25%. Constant mesh/sequential gearboxes with a chain final drive like the 140 has are roughly 12-14%. Even if the engine power was identical between the two, you could gain 5-10% just from reducing friction with the 140.

The 140 makes more power because it revs far higher than the 212, but that means it makes a lot less torque. Gearing it might take some forethought or trial-and-error. Countershaft sprockets are probably not available in industrial sizes like #35/40/41 and are more likely to be 420 or 428.

My main concern with the 140 would be keeping it cool. It's going to be behind your seat and really have minimal airflow. A fan that can move enough air to be useful will probably pull more current than the charging system can provide at lower RPM. You might also look at the GY6 variants since either engine is going to be a major retrofit and the GY6 has forced-air cooling.

 

[Kartorbust]

If there is a way to put an oil cooler on the engine that would help a bit, as long as it's in constant air. These engines do not like to sit idle for a long period of time, let revving up while the kart is stuck in mud or what have you.

 

[itsid]

140.. (frankly on a four wheeler I might pick the 190) but still 140 over 212 any time.
since yes.. WAAAAY more powerfull.

'sid