Hello, I'm new to these boards. I have an RS4 3 and my original engine lost compression. I took my car up to a local hobby shop and bought a Dynamite Mach .15 RE engine, exhaust header, and 21 tooth gear. The motor would not start, and he tried everything he can think of! He is currently trying to replace the engine with another one (the same one). Both of these engines are brand new, and I bought the first one for $80.

My question is: If he cannot get this second brand new engine to work, which engine should I buy? I only race my friend, who has a 60mph TC3. We race on hard pavement in a big parking lot. The guy at the hobby store told me my RS4 3 should be at ~80mph from the 21tooth gear and new motor. Is that correct?

Some engine's I've looked up include:

OS .15 CV-RX
OS .12 CV-RX

My price range is ~$100. I cannot go much past that!!! This whole mach engine set-up has cost me $115 total, for the motor, engine mounts, RE exhaust header, and spring.

Help! I'll let you guys know today how it goes!

Thanks!
-Cody