Thread: 305 pushin 480HP?

Tweet

Originally Posted by like2gofast

Those are the exact specs I pun on camquest Mooney, with of coarse a drastic differance in results. Where did you get that program? And have you used it with real world results?

I used the desktop dyno, its a purchased program. I find it to be a little on the high side on the #s, but it gives you a real close ballpark for sure. And also tells you if you are going in the right direction with your ideas or not.

as far as building a race motor from a 305 baseline, I personally would not and would throw my money into that 350. I always considered 305's to be a good reliable cruising motor with a stroke that is hard to make real strong power from like you are wanting.

I'm using DynoSim Pro Tools and so far it looks to be low by about 2 1/2%. If I track 400, actual from dyno results is 410. This software was regularly $250, but is currently on sale for 99 bucks. I'm using 0.006" tappet lift for the seat-to-seat figures, so maybe if I stretched it out a couple of degrees on each side to cover the seat to seat figures, I might be right on the money.

Mooneye hit the nail on the head. Even if the software is off a bit, it will tell you which way to go with changes. Like I said on another thread here, I picked up 55 ft/lbs of torque and 90 hp for a fellow on another forum with a manifold and header change.

Here's a 10.0:1 355 Chevy with AFR Street 180 heads, 750 carb on RPM intake, 1 3/4" headers and a 276*/282* hydraulic roller cam with 0.502"/0.510" lift....
rpm tq hp
2000 375 145
2500 380 180
3000 410 235
3500 450 300
4000 480 360
4500 500 430
5000 500 470
5500 485 505
6000 450 515
6500 410 510
7000 360 485

So, it's not really that big of a deal to make 500 hp with a SBC if you use the right combination of parts. Further tweaking this combo by retarding cam timing by 3* resulted in 525 hp. Using a 2800-3000 stall converter and a rear gear around 3.90-4.10 would make this a good, strong street combination in my opinion. Engineering the squish to 0.035" to 0.045" should allow the use of pump gas and fully optimized ignition timing with no problems.

Like mooneye said, there's nothing wrong with a 305 as a cruising motor, but if you're going to try to move up to some serious horsepower, at least start with a 355 or bigger. The 305's have that tiny little 3.736" bore which precludes using heads with large valves. The largest valves you can get in there will still be shrouded next to the bore.