For the heads what is this airflow file? The cam choice at the bottom has one also "cam file", like what's it used for.

Also Right after induction flow like i put in the size carb and then it has 1.5 in Hg or 3.0 inHg . What's the difference i Dont know which to pick for my 750 carb choice.

Also Afr's 100%fully ported 195cc heads. What are those considered? wedge?canted?oval?rectangular

For cam specs what do i choose
.050 timing
or
seat-seat


Here's right off the spec sheet on the cam

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.51 0.52
Duration At 0.006 Tappet Lift 282 288

And that shoudl be it. Thanks for helping me.

 

You can download files with the specifications for airflow (air flow files) and cams (cam files).

1.5hg for 4 barrel carbs, 3.0hg for 2 barrel carbs.

Most heads are wedge, i think hemis are canted, both are descriptions of the combustion chamber design.

Oval and Rectangular refer to the intake runner design. Small blocks are rectangle, big blocks oval.

 

An airflow file has the flow specs (flow at lift) of the heads you are using. You can enter and modify custom files like those for AFR 195's. Click on the airflow math function on the top taskbar.

Check http://www.airflowresearch.com/ for the race ported specs on the AFR1 195's.

The 1.5inHg or 3.0inHg is the pressure drop associated with the carb's cfm rating. I believe 1.5inHg is the standard.

Use the seat-to-seat cam (.006) figures for DD2000. Who's cam are you using?

 

I think you use seat to seat for those durations.

 

awesome, yeah its a comp cams xe282hr

 

COOL! im gonna use the exact same cam n my 383ci.

You like that cam?? or didnt u installed it yet?

 

I don't think you use seat-to-seat there.... I think it's supposed to be .050" for that.

You use seat-to-seat for the various "dynamic compression" estimators; not for any kind of HP estimate. Think about it.... you could have 2 cams with the same seat-to-seat but one with very aggressive ramps and the other with very lazy ramps; would they make the same power? I doubt it.

From what I can recall from your other post with the #s in it, it was a little bit overly enthusiastic.

I'd guess your combo to be good for somewhere in the mid-high 400s of HP, maybe 460-475, at around 5800 RPM; and near 500 ft-lbs at around 4500.

 

Incidentally...

http://www.airflowresearch.com/dyno/chevy_dyno.htm

Your cam is the 12-432-8; the 12-433-8 is the XR288HR.

 

damn, Dyno 2000 is pretty close on the money. Now only if afr went with a higher CR i bet there would be a nice improvment.

 

Consider also:

Is AFR paying either American Speed, or their own in-house staff, to build your motor; like they paid to come up with the highest possible numbers that aren't an outright lie?

Are you going to build 5 or 10 or however many identical motors, and pick the one to publish that makes the highest numbers?

Even if you duplicated the parts of their buildup that they're willing to tell you about, I doubt your motor would make as much power as theirs.

So I'd take their numbers with at least a part of a grain of salt, in terms of translating them directly to your results; not because they're "wrong" or anything like that, just that theirs are as optimistic as conveniently possible.

And while you're at it, think about how easy it is to finagle those numbers; tiny things can make a few HP here and a few more there, and those can really add up; just changing the oil from dinosaur juice to synthetic can make 10 HP or more of difference. Are you going to go through every single possible little tweeek like that, the way they did? Even if you know about them? If not, don't bet on duplicating their results. As an example, do they mention anywhere, whether they used the heads out-of-the=box, or the CNC ported version? If they're looking for the highest number they can substantiate, what do you think they used? Is that what you're buying?

I'd guess that the somewhat higher CR might compensate in part for their natural tendency to produce the highest numbers they possibly can, within the bounds of plausible deniability. It would be unrealistic to expect to get more than they did, just for that reason, however.

So I'd recommend that you not get too starry-eyed over DD's hallucinations (VERY easily influenced by improper parts specs) or those dyno numbers, but rather, use them as a guide to where you're headed. Note the RPM curves in particular. Regardless of the absolute power level, the shape of the curve that you get, should look much the same as their shape.

 

ohh ok, thanks man

 

With DD2000 triple check the data you enter & then deduct 10%. This # will be the potential your combo can produce, not neccesarily will produce.

 

DD2000 is quirky. I've been using it for about 3 years now. I figured out how to make it spit out "realistic" numbers under most conditions. I even got it to nail my roots-blown 383 within about 5 HP, and the torque curve was the right shape too!

Be conservative on the carb flow. If it's a 750, say it's 650-700. If you have big tube headers, use small tubes. And round your compression down to the next lowest tenth. For a N/A motor that about covers it.

Obviously, you must use the correct airflow measurements for your chosen head- AFR flow numbers on their website are realistic. Nobody else's published flow numbers are. Car Craft or CHP did a complete head flow comparison a few years back. It's still published on their website, but I already converted them into DD2000 head flow files. Email me and I'll send them to you, if you like.

Also, always use the .050 cam durations. The advertised specs are just too easy for cam manufacturers to play around with to be of any use in modeling max engine output.

 

A few other tricks to make your engine output come up closer to what DD2000 and AFR claim (as opposed to [i]reducing their claim to what would ordinarily be delivered):

1. Roller rockers
2. Roller thrust bearing on the cam gear
3. The lowest oil pressure you can get away with; 20 psi idle & 50 cruise is enough
4. DEFINITELY NOT a high-volume oil pump
5. Tight main & rod bearing clearance (like .0015"), so you can run thinner oil
6. Coated everything; ceramic on piston tops, chambers, & exh ports, and Teflon on bearings and skirts
7. Floating-pin pistons & rods
8. The lightest possible piston pins (like the thin-wall tool steel ones)
9. Rev kit
10. Cam bearings carefully located; with the oil holes at about 5:00 viewed from the front
11. Screen-type windage tray
12. Crank scraper
13. Active crankcase evacuation system
14. Knife-edge the leading face of crank journals & counterweights
15. Smooth & paint the inside of the crankcase
16. Optimized rocker geometry (for minimum "lost" actual vs theoretical valve lift)
17. Roller cam bearings (kind of $$$; you have to use a special cam journal size and have the tunnel in the block bored out)

I could go on and on; all of these are things that people will do every time to dyno queens, and the ones I've listed are all applicable to streetable motors. I bet I listed an easy 50 HP to the good of your combo right there, beyond what youd get just slapping the "industry standard" or stock stuff together as it comes right out of the box.

Some of these things you are probably already doing, like roller rockers.

There are other tricks, like low-tension rings for example, that I wouldn't do to a street motor; and others, like a dry timing belt instead of a chain, that run into some serious $$$$. But, all's fair in magazine articles or advertising claims of "dyno proven" engine combos. Winners and losers are created in the white space around the printing.

Most of these things aren't horribly expensive if you do them yourself, or at the right point in your build-up; some may be a bit time-consuming.

 

huh.... that sounds easy... smooth, like with a die grinder and sanding drum perhaps? I'll have to check that, i'm trying to imagine where i'd be painting... not a lot or room to move there..

 

Anything that isn't a precision machined surface inside the block can be painted.