Hi! What car are you running and what are your spur/pinion combinations? There many great engines out there but you can make your choice taking a few things in consideration, for example:
-> Roar rules. If you are going to run ROAR sanctioned events you will need a 21 engine with not more than 5 ports and a 7mm restrictor in carburetor venturi.
-> gearing of the car: some cars are geared too tall for a 21 engine, or the stock clutch is not setup for it. In that case you might want a 28 (or get the right spring/shoe combination for your engine/gearing/track conditions).
Here are some suggestions:
For the 21, 5 ports, Nova has the ISON GT which is reliable and fast. Hard to beat for the price tag. RB has the BXR DI5 but it's not cheap. The OS speed 3 port engine is insanely fast but expensive too (but maintenance is cheap). The Nova-Maxy Cinco BT is great engine too with lots of power and very reliable. There is also the Reds 5 port which is a screamer and quite affordable. There is also the Picco Boost.
If you can run a 21, 7 port there is the Nova Bonito. That motor is a beast in GT. RB came out with the new RALLY Xtrem V2. There is also the ISON 7 port but you might want to put a bigger cooling head on it to deal better with the heat. The OS speed 7 port is a monster powerhouse, a little expensive but maintenance is cheap.
If you want insane power (like the OS speed 7 port) you can look at 9 ports like the Rally Flash PT. It's a monster.
If you want to try a 25 engine, the Nova Roma is very fast.
For the 28 there is the Picco Boost and the Nova 28.
Last edited by Joe Kimble; 10-13-2014 at 08:40 PM.