Does anyone know of a free desk top dyno we can use online?

Yeah, it's called Team Chevelle :D

Just go into the Engines or Bench Racing forum, post your combo, and a dozen other people like me, who can't find anything better to do when at work, will plug your numbers into thier store-bought copies of Desktop Dyno and post them for you.

okay 385 505 (http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi/topic/4/23711/2.html?) what do you come up with?

Well, there's a few things I need to figure out first. The motor specs I read stated a 10.53:1 comp. ratio, but running the specs on the head cc's (120), gasket thickness (.020"), deck clearance (I used .009" down in the bore), and guessing gasket bore (I used 4.375"), gave me a compression ratio of only 9.15:1.

Here's the 9.15:1 results:
491 h.p. @ approx. 5000 rpm.
581 ft/lbs. @ approx. 4000 rpm.

Ignoring the programs' compression ratio calculator and manually entering a 10.53:1 ratio:
529 h.p. @ approx. 5000 rpm.
614 ft/lbs. @ approx. 4000 rpm.

Either way, the other post was right in saying it will be a torque monster, with the lower of the 2 simulations showing 531 ft/lbs from 2K rpm! (the other higher comp. version shows 557 ft/lbs at the same rpm) Neither went below 500 ft/lbs. 'till past 5K rpm.

Well not 385 but let me try......


Dual Plane Single Plane
H.P. T.Q. H.P T.Q
2000 204 536 2000 189 497
2500 266 560 2500 256 526
3000 325 568 3000 314 550
3500 395 593 3500 392 587
4000 460 603 4000 465 610
4500 520 606 4500 535 624
5000 560 588 5000 585 614
5500 575 549 5500 608 580
6000 567 496 6000 607 531
6500 545 437 6500 585 437

A few months ago Chevy-Hiperformance dyno a 496
with the same cam you have 10.27cr Edelbrock RPM
heads and Vic Jr.same carb it made
600tq@3900/625h.p.@6200

Based on what I have seen in this program
Your at 600tq@3700-4000/585-600h.p.@5800-6100rpm

Hope this Helps!
Darrell

a 107lsa installed at 106.5

Sorry I dyno it at 110isa installed 106 +4
it still within 5h.p. 569/605

Let go to the smokemup.com to use the online cal
595h.p.20%=476rwhp 3800lbs Chevelle=122.06mph in 1/4

1320/122=10.8196 e.t (very good traction)
1330/122=10.9016 e.t. (acceptable best traction)

I think you will have your 10.99 slip!
Good night! or morning for some..
Darrell

26 cc dome on the pistons if that makes any difference. Thanks guys, I was just curious as to what the computer says.

Makes a helluva difference. The compression ratio calculator figured a flat-top piston.

I also just noticed I mis-typed the exhaust duration in the cam math.
With the cam entered correctly and with a 10.53:1 compression ratio:
610 hp @ approx. 6,000 rpm
612 ft/lbs @ approx. 4,500 rpm

Plenty bad a$$ for any street driven car.

I've never really put much stock in DD, but it's fun to play around with. For kicks I plugged everything in for my new combo (including actualy flow numbers from my heads) and it shows:

788hp@6,500 :rolleyes:
680ft/lbs@5,500 :rolleyes:

I'll know in a couple weeks what it will do on a real dyno. Would have prolly had it on there already if not for setbacks like a stripped head bolt that had already been helicoiled graemlins/angry.gif

I use DD just for fun as I have issues with the program.

For example, if I enter all my engines info with fliw numbers, etc...I get 649 hp & 620 ft/lbs of torque.

Now, if I use the programs oval port head, large valves, pocket ported, it comes up with nearly 680-690 hp!. Now if you go into the custom air flow section you'll see the valve sizes they computer the power on are not 2.19/1.88 large valve sizes, rather 2.02/2.60 sbc valve sizes. The air flow section also uses a standard 25" of depression instead of the more accepted 28" of depression. The flow numbers for their pocket ported heads are also lower than mine are, yet with all this taken into account, the programs heads make more power?

Also, if you read the instructions carefully, most street strip motors need to choose small tube headers as the program bases small vs large based on a comparison of the tube diameter to the exhaust valve diameter. The programs muffler option is terribly inaccurate IMO...most good street/race exhaust systems do not reduce power as much as the program predicts.

junk in - junk out.

You can do a search for DD2000 and get alot of past user comments. I have been able to set up baseline engine sims for simple motors [ie. 395/325, 454HO/425, 454/390] Doing so, I have been able to compare how subtle changes in cam or cylinder head flow should effect an outcome. The key is in the setup of the head flow data. You need to set it up at .050 data points and make sure the numbers are input to 28". Camtiming is another problem. I have found the most accurate data to be when you base the cam duration to .050 plus 58 degrees.

Originally posted by 10secBu:
I use DD just for fun as I have issues with the program.

For example, if I enter all my engines info with fliw numbers, etc...I get 649 hp & 620 ft/lbs of torque.

Now, if I use the programs oval port head, large valves, pocket ported, it comes up with nearly 680-690 hp!. Now if you go into the custom air flow section you'll see the valve sizes they computer the power on are not 2.19/1.88 large valve sizes, rather 2.02/2.60 sbc valve sizes. The air flow section also uses a standard 25" of depression instead of the more accepted 28" of depression. The flow numbers for their pocket ported heads are also lower than mine are, yet with all this taken into account, the programs heads make more power?

Also, if you read the instructions carefully, most street strip motors need to choose small tube headers as the program bases small vs large based on a comparison of the tube diameter to the exhaust valve diameter. The programs muffler option is terribly inaccurate IMO...most good street/race exhaust systems do not reduce power as much as the program predicts.

junk in - junk out. The valve diameter and pressure drop can be edited within the custom head flow file. I entered the actual values for my heads including 28" where they were flowed at. I agree on the muffler stuff with DD2K. I've done back to back testing at the track with my car on more than one occassion with more than one brand of muffler. My car ALWAYs ETs better with straight through 3" mufflers AND tailpipes. May be different on the new setup with more cylinder pressure, etc..., but I somehow doubt it.

I do the same Ken, as I enter my flow numbers, valve sizes and choose 28" of depression. It irritates me that the base flow modeling in DD2000 is so inaccurate with respect to valve sizes for bbc and also can't figure why they use 25" instead of 28". I'd bet the difference between 25 and 28 is where DD2000's own head flow files show more power than my own data does.

What is most irritating is those who just don't know will buy a program like this, use the built in head flow files and think they are making serious power when in reality the programs internal setup is compromised and inaccurate unless you know how to correct for these things for more realistic output numbers.

For my previous 414 bbc, the numbers I got were pretty close IMO...it showed 580 hp which given it's MPH & ET was darn close to on track performance.

Originally posted by 10secBu:
I do the same Ken, as I enter my flow numbers, valve sizes and choose 28" of depression. It irritates me that the base flow modeling in DD2000 is so inaccurate with respect to valve sizes for bbc and also can't figure why they use 25" instead of 28". I'd bet the difference between 25 and 28 is where DD2000's own head flow files show more power than my own data does.

What is most irritating is those who just don't know will buy a program like this, use the built in head flow files and think they are making serious power when in reality the programs internal setup is compromised and inaccurate unless you know how to correct for these things for more realistic output numbers.

For my previous 414 bbc, the numbers I got were pretty close IMO...it showed 580 hp which given it's MPH & ET was darn close to on track performance. It will be interesting to see how the numbers it crunched for me compare to a real dyno test. I'm estimating 750hp/650ft lbs, so maybe they're not that far off with accurate measurements. Might be time for a new carburetor though :( I'm not sure if this little HP950 will be adequate enough for the new engine. That's one of the nice things about dyno testing/tuning. I can get all this sorted out before I ever hit the track.

Same here Ken, although mine will be going back on the same chassis dyno as last winter...that is if and when I get the parts back from the machine shop and have time to assemble the dang thing.

Does your dyno operator have some different dyno carbs you can try out and see which makes the most usable power/tq?

I opted to engine dyno rather than chassis dyno as it's hard to get any meaningful information on torque curve with a big stall converter. 10-4... My engine builder has a plethora of carbs for me to try on the dyno. Grimes operation is 1st class. When I went by this morning he had 7 Hemi big blocks under construction for one customer :eek:

Thanks Darrell, 385, I appreciate the input. 10.80-10.90 would be great, now its time to " get r done" :D