HPI RS4 EVO3 Engine Swap
 

Hi everyone,

My t15 engine just fried up. I found the necessary parts, but they are very expensive. So I want to swap it. Found a used savage xl 5.9 engine wich is good condition in my local area. ıdk if it fits, owner dosen't have a clue. I saw someone else in youtube done this project but am not sure what parts I need for this or can I just drop the engine and run it?

There are basically no parts to fit a bigblock on the spot of a smallblock, only for some popular Traxxas models you can find conversion kits but they will not work on your HPI.
People who have done that did make their own parts.

Beside that, a bigblock will not run faster than a smallblock unless you can find other fitting gears. to convert the huge torque to speed (if that is the goal)

Ok thanks for the tip,
I can make some custom parts for big block and speed is not important in my case, I just want to back on feet this rc
I worried about is there enough space in my chasis for this big block? cause in that video the engine was placed horizontally and back of starter is open, but t15 is standing straight and the starter almost touch the rear swing arm.
For the t15, the length from the starter motor to the end of the gears is 110,2 mm and almost touch to rear swing arm
K5.9 is 112mm
Also can I put the existing pinion gear from the t15 to the big block to match the gearbox?

what needs fixing on the T15? I may have parts if you still want to salvage it....

it's a perfect fit if u put a rotostart on it..:blush:

https://i.postimg.cc/x1rQfPyJ/20231231-192832.jpg

Block, piston, sleeve and gasket.

As someone who has built 8 Nitro RS4s over the years, including one with a 3.4cc engine shoved into a smallblock form-factor, I can confidently tell you that 5.9cc is MASSIVELY overkill for that chassis. The chassis will be dangerously unbalanced with an engine that large, and the tires won't be able to stick that much torque to the ground anyway. You're probably imagining something like stuffing a LS1 into a Miata, but it's actually more like stuffing a LS1 into a go-kart -- it's more power than the platform can possibly use, it will handle like shit, and you WILL crash it.

The stock 3.0cc engine has more than enough power unless you're trying to go above 60mph, and in that case you're better-off buying a higher-end smallblock engine like an OS 21TM. It will outperform that 5.9 engine in the way that a touring car actually needs -- high RPM and top-end power. Truck engines provide monster torque, which is useless for touring cars.

If you just want to get the car up and running again, any pullstart engine from 2.1-3.4cc (aka .12-.20 cubic inches) -- even cheap no-name Chinese engines -- will work just fine. Just buy one on eBay and save yourself the pain of what will ultimately be an extremely difficult custom job with disappointing results.

Wow what mount did you need and what mods were done to accomplish this? i want to try for a .21 and have no idea where to start

If you see that picture and still have no idea where to start then I doubt any succes from you. What I see on that picture is that he made an own chassis because the original is purple and has slight bended side edges, those bended edges prevents the mount of a wider engine. Basically you need any kind of bigblock mounts and drill some holes in the chassis.

Thanks man, that's the answer I was looking for and I really appreciate it. After the engine failed, I thought I could have some fun by turning this chassis into a project car and running it. The reason I chose a bigblock is because it's more like swapping ls in to a miata :))) But like you said, that could be torture..
Maybe I'll do it, or drop something like a kyosho 28 or hpi 25 on the chassis. There's plenty of those around.

It's an aftermarket chassis plate. Looks like it's from GPM or similar.