engine build
11-21-2007, 12:20 PM
#1
5th Gear Member
Thread Starter
Join Date: Jun 2005
Location: So. California
Posts: 2,258
engine build
http://airflowresearch.com/ford_dyno.php
third one down
im thinking of going with this setup....same heads, cam, i may keep my 650 edelbrok and air gap intake.
third one down
im thinking of going with this setup....same heads, cam, i may keep my 650 edelbrok and air gap intake.
11-21-2007, 01:36 PM
#3
6th Gear Member
Join Date: Aug 2007
Location: Elk Grove, CA
Posts: 5,896
RE: engine build
You better have some really short gears if you plan to drive that on the street. Sure, it's got top-end power, but it has almost no low-end. Streetability is going to be very poor.
11-21-2007, 05:48 PM
#7
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
RE: engine build
It's gonna have crappy streetability because they used large heads, a large cam and a huge *** intake on a small displacement short stroke engine. Yeah, it has good top end power, but it's not gonna want to move air that well at lower rpm. You'd need quite a bit of gear to make up for the lack of bottom end and have it move out from stoplights. Also look at the other 302 on their site, using smaller heads, smaller cam, smaller intake....still made about 420hp, but with much better bottom end power and drivability. You'd be trading a measly 30 peak hp for better average power in the rpm range you do 95% of your street driving in. The other thing to consider is that peak horsepower is just that, PEAK horsepower, and speaks nothing of the rest of your power band. Peak power numbers are only good for those that want to sit around and brag about how much power they have on paper, but AVERAGE power across your usable power band has a bigger impact on performance that peak power. Quite often the fastest guy isn't necessarily the one with the "most power" but the best average power. The idea is to optimize power across an entire rpm range you operate in, not get some high maximum number. Peak power only occurs at 1 rpm......what about the other 6,000 rpm give or take?
11-21-2007, 07:26 PM
#9
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
RE: engine build
If you run between 4-6k then you want the best average power in that range, 7-9,500rpm, the best in that range, and so on and so forth. On a street car you also want best average in power in like 4-6k or whatever your top end rpm range is, but you also need to consider lower rpm power for street driving. Ultimately every street engine has to trade some top end power for some bottom end power, in order to retain drivability. Either that or you just drive a car that runs like crap until you get over 3,500rpm. I dunno about you, but when I drive my car on the street, I like to be able to step on the gas and not have to wait until AFTER I would have already shifted for my engine to get up off it's own face. Most street builds though, if you pick a reasonable peak rpm range, up to say 6,000-7,000rpm(depending on the build) and maximize the average power for the top 2,000rpm or so and build it for that, it'll end up still retaining enough bottom end to drive really well. Otherwise, if you shoot for 30,40, or 50 more peak power, the power band looks more like a spike and less like a flat line, so the average power may only go up slightly and make you just a little bit faster, but then it drives like crap 90% of the time. The key is to match the engine build to the car's weight and gearing and use, figure out what a good maximum rpm is for power while still remaining a good street driver, then build it that way. The problem most people have is they get carried away trying to find more peak power, and before you know it end up going too big, not being any faster, but getting worse mileage and drivability.
Race engines are SOOOOO much easier to build though, since you don't have to worry about what it runs like under a certain rpm, so you can build and tune it for best power across a narrow top end rpm range. Who cares if it runs like crap in the pits, all you're doing is doddering up to the starting line anyway, you're not driving in city traffic.
Race engines are SOOOOO much easier to build though, since you don't have to worry about what it runs like under a certain rpm, so you can build and tune it for best power across a narrow top end rpm range. Who cares if it runs like crap in the pits, all you're doing is doddering up to the starting line anyway, you're not driving in city traffic.
11-21-2007, 09:53 PM
#10
D.R. THE PATHETIC DORK
Join Date: Jun 2007
Location: West Virginia
Posts: 30,863
RE: engine build
I personally think AFR has inflated dyno number there.......as I had the same combo only 11 to 1 compression and flywheel was probably close to 400 as it ran 12.20's @112 so maybe 340 to 350 rwhp[&:]