Can someone run a desktop Dyno for me please?

Curt C. · #1 (**permalink**) 12-07-2003, 05:12 PM

351W (standard bore & stroke), 9.6 compression with AFR 185 heads (61cc with 2.02 valves) Holley 750 DP, cam has following specs: Duration advertised 296/306, at .050: 236/246, lift - .520 / .538, 1.6 rockers' 36 degrees total timing. I want to compare a Vic Jr. intake to a Air Gap RPM intake on this combo. Very curious to see what pops out. I know the Vic will make more top end power and the RPM will make low end torque, but I want to evaluate the area beneath the curve. Myabe post the graph if possible. Thanks very much in advance for any takers.

blykins · #2 (**permalink**) 12-07-2003, 05:35 PM

I'll get it for you...give me a few minutes.

blykins · #3 (**permalink**) 12-07-2003, 05:47 PM

Curt....I can't figure out how to cut and paste the graph....as soon as I figure it out I'll post it. However....

Single Plane Intake -- 449hp @7000, 384lb-ft @5500
Dual Plane -- 394 @ 6500, 353lb-ft @ 5000

My guess is your cam is more suited for higher revs....if you really want a torque monster, you might want a cam with a little less duration.

BTW, I had to custom enter the cam specs...if you know specifically what grind it is, let me know....I can redo it.

Jack21 · #4 (**permalink**) 12-07-2003, 06:04 PM

Curt, I don't want to come across as a smart a$$. We can run your Desktop Dyno configurations to "What if", this, or "What if" that, because that is what it was designed to do. But the beauty of Desktop Dyno is not the peak numbers, but the whole TQ & HP curve, and how interchanging components will change this.

If you're at the engine configuration stage of your Cobra (or Street Rod, or Muscle Car) project, you need Desktop Dyno on your own PC. For the price of a decent set of valve cover gaskets, you can play "What if" with componentry until you're satisfied that your engine configuration will give you what you want, where you want it.

I played the configuration games with Desktop Dyno for a solid year before the engine went to the machine shop. Hours went into this comparing options, and printing graphs. And you will too if you do your own design work before laying a wrench on the engine, or spending a dime on parts.

Then come back to the Forum and we can share what you won't find in the books, or software.

Curt C. · #5 (**permalink**) 12-07-2003, 06:47 PM

This motor is the old 385 hp motor with AFR heads. That cam was the flat tappet hydraulic that was used prior to going with a roller. This motor with the supplied vic. jr. thumps out 377 rwhp at 6000 rpm and 354 rwtq at 5000 rpm. The dyno was damn close with respect to HP: 449 x 85% = 381.

see attached dyno

I am trying to figure which manifold is better. Car is a Saturday Night Special that see around 4 weekends of road racing (NASA, SCCA) a year. On the track I shift at around 6200 so the operating range is 4000 - 6000.

Edelbrock says the Air Gap is for 1500 - 6500 and the Vic jr. is for 3500 - 7500. I went back and looked through 5 some years of MM&FF. Almost every dyno-tech story of a small block motor making over 375 hp has a Vic jr. on it. Found two articles that specifically compared the Air Gap to Vic Jr. First article: 302, Windsor Sr heads flowing 275 at .600, XE 282 cam 224/232 duration, 555/565 lift. Westech engine dyno. HP with the Vic peaked at 383 at 5700 versus 374 at 5700 for Air Gap. The vic started picking up HP over the Air Gap at 5100 rpm.

Second article: 306, AFR 185's, XE274hr cam: 224/232, 550 lift. With the Air Gap 425 hp 6000, 390 TQ at 4800rpm. With the Vic, HP was 439 at 6200 and 390 tq at 5200. Cross over was 5200 rpm.

These results lead me to believe that the Vic is a good operator in the 4000 - 6000 range and will probably have more area under the curve than the Air Gap in this range. Everyone seems to believe that if you are not shifting at 7500 you dont need the Victor. No question, the Air Gap has better drivability, but it appears that the Vic has a place on the street as well.

Blykins, save it as a JPEG, shrink it to 400000 bytes or under and attach it in the box at the bottom of the reply page right under "Options"

blykins · #6 (**permalink**) 12-07-2003, 07:05 PM

blykins · #7 (**permalink**) 12-07-2003, 07:07 PM

blykins · #8 (**permalink**) 12-07-2003, 07:10 PM

Sorry that you didn't get numbers on it....I had to crop it that much just to make it under the limit. I gave you the numbers up above...and I know you wanted to see the curve...

Curt C. · #9 (**permalink**) 12-07-2003, 08:22 PM

Blykins, that is great. Thanks so much. I printed your attached graphs and then carefully laid the Vic over the Air Gap. I then penciled the Air Gap lines onto the Vic graph. From 4000 to 6000 the Vic is above the Air Gap in both TQ and HP. Crossover starts right at 4000. Of course the gains are even greater above 6000. I thought the Vic would have more area under the curve, just didn't think the gains would start as low as 4000.

I am going to change the title of this thread and see if I can get some folk's comments. BTW, my cam is retarded 4 degrees. Not sure if that makes a big difference or not.