The thing he's (blue thunder) not being real specific about are the heads because the DD has several different head and head porting configurations that go into the equation. With the differing levels of head porting that are on the DD it can make a big difference on the power outcome of the engine in question. Just my .02

I'm coming up with 472@5500rpm for horsepower, peak torque of 531@3500 if the intake centerline is 107 degrees. if I advance that 4 degrees the horsepower drops to 456@5500 and torque goes up to 534@3500. let me know what your cam card says for intake centerline angle. I'd really like to see the compression ratio up around 9:1, maybe a little more than that. Also, I'm assuming this is a hydraulic flat-tappet cam.

Right you are Kaama. I didn't know which head selection would be closest to the 6055 aluminum heads. I think I was using canted rect port. Hopefully the fact I have a matched induction system (performer rpm) is of some benefit. Crazyhorse has been working on the edelbrock alum head idea, maybe he knows.

Dyno, I hope you are right... that would be a nice boost in performance year over year.

Dave

I guess we were typing at the same time crazy. The Intake CL straight up is 107* The LSA is 111. The cam is comp. CBX4 270H-11 Yes on flat tappet cam. 9:1 or better is on next winters to do list.... ;) Due to cast assemblies I am only concerned with the torque curve below about 5200rpm. My hp will be peaking over that, but I want the torque falling right at 5000rpm. What selection did you make for heads?



Dave

Crazyhorse,
Here is the flow data on those heads if you want to plug in the exact numbers to a DD .flw file.
http://www.edelbrock.com/automotive/head_flowdata.html
Bob

Here it is, rpm, horsepower, torque;
2000 194 510
2500 249 523
3000 301 526
3500 354 531
4000 401 526
4500 442 516
5000 469 493
5500 470 449
6000 456 399
With the airflow numbers plugged in;
2000 193 507
2500 247 519
3000 298 521
3500 348 523
4000 392 515
4500 428 499
5000 445 467
5500 433 413
6000 408 357
If I were a betting man, and we were going to run the engine on the dyno, I'd probably guess that the second set would be close, but I've lost this bet with KAAMA before.

Looks like a good, flat torque curve for a marine application. What do you guys think? Torque drops off right about where I want it to as well. I'll play with the dd2000 some and see if I can get the same numbers as you crazy.

What rpm would you guys prop this boat to, I was planning for 5100-5200rpm, but maybe a little lower would be better.

Thanks for the help,

Dave

Crazyhorse,

Can someone run mine for me???

Here it is

Displacement: 502
Heads: oval port merlin's 2.19/1.88
Carb: 850cfm Holley
Intake: Holley, Single Plane Strip Dominator
pistons: Stock GM
Comp Ratio: 8:5-1 I believe
Cam (Comp Cams XS282S "Solid flat tappet"): Gross Lift 590/598, dur 282/290 @.015, dur 244/252 @ .050
valve timing @.015 IVO 35 IVC 67
EVO 79 EVC 31
Lobe separation 110*
Cam ground with 4*advance and installed straight up.
thunderbolt IV Ignition
Stainless marine exhaust

I am curious what I am making. My guess is 525 - 550??

Here is what I came up with Panther. Had to take a guess on the airflow of the heads. Used small tube headers as the exhaust. Crazyhorse can do better I'm sure. Just practicing.... Seems my numbers are low :confused:

RPM HP Torque
2000 102 267
2500 152 219
3000 193 338
3500 252 379
4000 318 417
4500 382 446
5000 426 447
5500 450 429
6000 451 395
6500 443 358

I'll be curious to see what crazyhorse gets

Dave

Here's the results I get with small-tubes/no mufflers, single-plane intake, seat-to-seat cam timing(this is a solid-lifter flat-tappet grind with .016 lash, that's why the cam timing figures are at .015 lift),rpm, hp, tq,
2000 183 481
2500 241 506
3000 300 525
3500 368 552
4000 432 567
4500 486 567*
5000 522 548
5500 530*506
6000 517 452
6500 486 393
Making the large tube/with mufflers selection;
2000 172 452
2500 228 479
3000 286 500
3500 353 529
4000 416 547
4500 470 548*
5000 506 531
5500 513*490
6000 499 437
6500 464 374
Either way it looks like a nice running motor.