SquidBonez
Active member
I know most people here have experience with small blocks, but I've seen a few people who run big blocks here too. Looking to run a Stage 2 Predator 420 (that is billet rod/flywheel, .308 cam, 65lb valve springs, chromoly pushrods, stock carb with larger jet, high flow air filter, and a header pipe) on a project and I'm looking to get around 25-30 horsepower and 6000-6500 RPM. No porting, polishing, or milling. I managed to come across a dyno sheet from a 420 race engine that put out 35 horsepower, 38ft-lbs, & a little over 7000 RPM (see below). Problem is that I have no idea if there was any porting/polishing/milling, and it was also running an aftermarket carb, so my output will probably be a bit lower. That being said, does anybody have any dyno numbers or estimates for a Stage 2 Predator 420 or any other GX390 clone?
420 Dyno Sheet:
420 Dyno Sheet: