Magnum 300 crate engine - how should it go when tuned up right?

MRGTX said
Thanks to all for the input.

Before I start messing with stuff, I wanted to collect a baseline for performance. I hooked up the G-Tech meter and did half a dozen 0-60 runs. This model uses accelerometer and GPS so it’s pretty decent, I guess.

Weather is low 80s today, low humidity. Elevation is 1000 feet above sea level or so.

I’m about 200lbs, my (very supportive) wife is 130ish lbs who was in the in the passenger seat plus a full tank of fuel.

Holding it to the floor, it shifted at 5,000 on its own. I know that governor weights are an estimate but that’s pretty far off too...maybe that’s ok in this case.

So 0-60 was pretty consistently mid 6 second range. Not pathetic but far from good.

Based on my estimated 3600lbs, the G-tech calculated that as 225ish hp for whatever that’s worth.

So it’s a full two seconds slower than my basically stock 6spd Coyote Mustang as measured with the same gizmo on the same roads.

Read through the entire thread. Good move with the G-tech-I had one of those and wish I never sold it. Ran it at the strip many times and it was within a tenth of the clocks every time.

Your engine's performance is just about spot on I'd say. The only thing that messes me up is you say it's no stronger than the 318 it replaced?! Your 360 should fry the tires effortlessly and as Moper has said that engine would be out of breath by 4500-5000 rpm. IIRC the G-tech calculates HP based on weight and G's so that 225ish HP would be rear tire shove and that is just about 300-320 @ the flywheel. Your engine is fine and making the power its supposed to. I'd want to know why it isn't snappier off the line though.

Whenever I take on a tuning/setup case like yours I follow a procedure:

1. Remove all plugs note heat range I'd want a Champion RC9YC and perform compression test-write it down. If you find a cylinder way off stop here. Any tuning will be a waste of time and effort.

2. Jack up car and weld in O2 bung. Install O2 meter. I have an innovate LM1 that taught me I didn't know anything about a carb first time I used it.

3. Get a good dial back timing light. 95% of all "carb" problems are timing and timing curve problems. Verify firing order. Disconnect vac advance and observe initial timing. Rev engine and observe total timing and at what RPM its all in at. I would want to see 14-18 at idle and 32-33 all in by 3500 on something like that.

4. If step 3 doesn't reveal an issue then start carb tuning. I'd start by complete disassembly and pin all holes and write it down. Demons are notoriously lean and have a very unconventional emulsification package. I'm not getting into that novel here.

I don't think your engine is far off--I think you and all of us are spoiled by just how good modern vehicles are. Good luck and let us know how it goes. J.Rob