Here's what I put into Dyno2000 and its spitting out numbers that I don't trust. 30-over (roller) 302 10:1 single plane intake trick flow TW heads (flowing 251/187 @ .5" published numbers) 224/234 @ 50 roller, 110 LSA, .496/.520 lift Large tube headers with mufflers Guesses at the crank?
I come up with 450 hp @ 6500 and 424 tq @ 4500, one thing you have to remember is that's what this particular set up could make with perfect assembly, timing and air fuel ratio. That would also be 382 hp and 360 tq at the rear wheels with a 15% drive train loss.
Why are my numbers so darn high??? I'm getting a clean 550hp @ 6500 and 460tq @ 5000. If I plug in the flow numbers into the calculator (251cfm and 302ci) it comes up with a potential of 561 @ 8600 rpms. The funny part is, if I uncork it just by removing mufflers, it says 600 hp @ 8000. I handicapped it as much as I could with a dual plane intake, 9.5:1 compression, 600 cfms, small headers and mufflers, and I'm still getting almost 450. Seems like I'm in the market for a new dyno simulation.
The head flow default seting for the flow measurement is pressure drop 1. in H2o (water) most heads are tested at 28. here's where I got all the head flow numbers http://www.jason.fletcher.net/tech/flowdata/aluminum.htm
I usually get my head flow data at http://users.erols.com/srweiss/tablehdc.htm but that link you gave is excellent for exactly what I need here. I did mess up the flow data. The flow data website I had said that it was at 1 in H2O, but there was a little asterisk beside a few heads' data that (had I paid attention) would have told me that those particular numbers were at 28". Thanks for helping me by bringing that to my attention. Now we're talking a little more realistic. I come up with 450hp at 6500 and 427tq at 4750. The use of roller lifters in this simulation with this "mild" a cam still makes the torque curve a little optimistic, but peak hp should be pretty accurate. I'm going to play with more head flows and cams and I might post some more charts later. Thank you so much.
I think the hp number is also a little optimistic. In my opinion, the low compression, small cam and low rpm will suppress the hp numbers. The heads and intake will support 400+ hp but some of the complimentary parts will be the limiting factor.
Well, I could pick up another 20 hp by jumping to 11:1, but compression is not the free ride everyone hopes for. I agree that for an optimum combination, about 11:1 is more preferred, but I'm not a compression junkie. And, this is a pump-gas-only racer. Its a complicated story, but when you add up the lowest common denominator (including our personal preference), premium is the limit. Combine that with my feeble ignition tuning skills and 10:1 is like a warm blanket. But you guys are the Ford experts and I value your input greatly. Thank you. The last Ford I had was a 7.3L powerstroke As I get closer to choosing parts I'm sure I'll be picking your brains for more stuff. You might even talk me into more compression, but that will take a lot of convincing.
Being in your "comfort zone" is very important. Increased compression will also enable you to run a little more camshaft which will allow you to take more advantage of the cylinder heads and intake. I am not trying to talk you out of or into anything but it is something else that you can consider.
Google Engine Analyzer 3.0. Good program. Just ballpark, I agree with the 400-450hp range. I'll run the specs through tomorrow sometime if I get the chance. For the record, my cousin's 410hp 289 runs exactly by the program once you figure in drivetrain loss and the weight of the car in the eighth.
Deesktop Dyno was a program that was built for racers initially, and those guys ran some low friction motors. DD always seems to read a little high.
DD doesn't use friction as part of its simulation, other than a standard friction number. For instance, if you plug in a Chevy 400 and get a simulation, then switch it over ot a Pontiac 400 it doensn't change the dyno graph even though the Pontiac has heavier guts and larger main and rod bearings. It just uses VE to estimate power. I agree that DD is a little optimistic, but that's to be expected. It assumes a proper fuel mix, proper valve control, a certain amount of ring seal, proper ignition curve, etc. Rarely do you actually get perfect anything on a real dyno. I always assume that its about 4% higher than what you can realistically achieve in real life. My first and only engine that I built myself from the ground up was estimated at 420 on DD and actually only makes about 390 I think I got some rings upside down
