Having some free time, I spent most of the morning playing with cam profiles on DD. I came up with some interesting stuff, not the least of which is that DD likes a lot more cam split than is offered by most cam mfg. While we of the Order of the Blue Oval are used to seeing 8-10 deg of int/exh split, I found that most profiles didn't max out the power possibilities until you reached an 18-22 deg split.

After much hard and strenuous work (read: playing ) using the 514 Motorsport block and SCJ heads as a starting point, I came up with the following theoretical grind.

Solid Roller (all specs are seat-to-seat)
Intake Lift @ valve - 0.500
Exhaust Lift @ valve - 0.600
IVO / IVC - 20 BTDC / 60 ABDC
EVO / EVC - 70 BBDC / 30 ATDC
Lobe Center - 110 deg
Intake Duration - 260 deg
Exhaust Duration - 280 deg
Overlap - 50 deg

With the 514 block and base flow numbers on the SCJ heads, plus an 900 cfm carb, a dual-plane intake, 2.25" primaries on the headers, and using 11.0:1 CR (aluminum heads plus huge overlap will allow it), I got the following numbers....

RPM HP / Torque
2000 251 / 658
2500 319 / 669
3000 382 / 669
3500 445 / 668
4000 503 / 661
4500 553 / 645
5000 587 / 616
5500 597 / 570
6000 583 / 510
6500 551 / 445

Just for fun, I left everything the same and switched to a single-plane intake. As expected it gutted the low-end but beefed the max HP number....

RPM HP / Torque
2000 231 / 605
2500 303 / 635
3000 371 / 650
3500 442 / 663
4000 508 / 667
4500 566 / 660
5000 607 / 637
5500 623 / 595
6000 612 / 536
6500 588 / 475

Look at the max torque number. It's virtually identical, but 1500 RPM higher. It's a good example of how moving the torque peak up and down the powerband changes the charactaristics of the engine.

It would be supremely intersting to see how this setup applied in an actual build. If I just had the bank account to play like this in the REAL world.

If anyone knows of a free image hosting service, I will put up the graphs for this build.

Brad

 

This is interesting but at the same time confusing and I think its a problem with desk top dyno's in general. Looking at your 2 examples peek HP is at the same place regardless of manifold. This should not be. Both Hp and Tq should move up and down the range when the changes is made.

To be honest I really don't think these programs are good with strockers in general and overall only handle a small range variables. I have used Engine Analyzer and find that changes I make to it are not always correct based on proven numbers.

 

Actually, the only thing you are changing is the overall location of the torque peak. HP is just a mathematical representation of work - force applied over time, which in this case is torque x RPM. The fact that the peak HP number appeared at the same RPM on this test is just a mathematical anomaly.

The real interesting part is how the torque peak moves significantly up and down the RPM scale as airflow management strategies change, even though the change was relatively minor. It just shows how truly important it is to give a lot of thought to your build before ever turning a wrench.

Almost forgot to ask... would someone with a more advanced engine sim run the above cam profile and see what you get? I'm interested to see what a more sophisticated sim turns up.

Brad

 

Out of curiousity I re-ran the sim, but plugged in radical cam numbers. You know, the the kind that would give you a really ragged idle but that everyone wants because it just "sounds fast". It blew everything. Torque was down by almost 150 lb-ft and HP was off by about the same.

But it would sound really cool (which better be your goal because it's gonna run like crap).

Brad