Mike20

Can I put a o.s 18 cv-r engine in my hpi rs4 3 evo nitro with not needing to get any other parts for it like engine mounts and use the same pinion gears

Solico

iTrader: (6)

I don't see why not, it was a direct drop in for the RS4 and rs4-2. In fact I'm about to purchase one as well for my RS4-2, if not slap in a TRX 3.3 / 2.5 in there.

GripTLR

it was a common engine swap from a .15 back in the day when the RS4 3 was relevant.

I believe it used the same engine mounts.

InTheZoneAC

if you get a trx 2.5 or 3.3 I would definitely look into replacing the rod with one from rb:
Traxxas HD Rod

The stock rod, unbelievably doesn't have a bushing to ride on for the piston side, so it's prone to breaking, splitting, detonating at any moment.

I've had an unused trx 3.3 in my nrs4 for IDK around 12+ years maybe, and just recently swapped the rod with plans on running it. Also be sure to preheat the upper part of the engine prior to breaking in to prevent any stress to the rod.

Mike20

InTheZoneAC

On my Nitro RS4 2 I have some aftermarket mounts with little heat sink fins, but I'd imagine you don't need different mounts since they're the same overall two piece design as stock. Just make sure if you get a trx motor that you get the right crank, I believe its a standard or threaded crank, whatever the rs4 uses.

Solico

iTrader: (6)

Any part numbers for that trx crank?

InTheZoneAC

https://forums.traxxas.com/showthread.php?8952385-5409-3-3-short-shaft-engine

you're looking for crank 5289, the complete engine is 5409

Scroll to post 8 and 9 for part number and visual reference. The rs4 uses the short shaft/multi shaft setup where you insert a thread and use a clutch adapter. I'm not sure if I'm using the traxxas clutch adapter or the original one from my old 15fe.