Thread: 383 air flow ????

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Ok, considering some heads for the 383 'maro engine. Be nice to me, I'm a Ford guy!!!!

Looking at 64 cc, for a CR of 10.8:1--or so sez the shop doing the engine--I haven't seen the engine yet, supposed to be done in a week or so. Anyway, assuming the builder is correct (he is a good builder btw), I suppose about 180 cc runners would do.....However, I plan on playing with things a bit, solid roller cam, and of course with the high CR it will be another E-85 fueled engine.... It does of course take a lot more fuel with ethanol, no problem there, a 750 or 830 reworked for ethanol should do fine (?) but maybe I might want to go to 200 cc on the heads and a tad over .500 lift on the cam???

I know, hard to say without the piston specs and squish data, but help me do a bit of guesswork, ok????

The best running SB 383 Chevys that I have seen use AFR 195cc Heads .

Originally Posted by tango

The best running SB 383 Chevys that I have seen use AFR 195cc Heads .

No argument.

383
AFR195 Comp #1095, 2.08"/1.60, 65cc (order heads with 64cc chambers)
Dual-plane, high rise with 850 carb
1 3/4" long-tube, equal-length tuned headers through mufflers
10.8:1 SCR
9.0:1 DCR with the following cam.....(note for other readers, you couldn't run this DCR on pump gas, but Dave is using E85)
Comp solid roller 12-702-8
http://www.compcams.com/Cam_Specs/Ca...?csid=302&sb=0
RPM HP TQ
2000 152 399
2500 193 405
3000 250 438
3500 321 481
4000 389 511
4500 454 530
5000 511 537
5500 542 517
6000 561 491
6500 554 447
7000 522 391
7500 489 343
8000 414 272
V.E. 102.7% @5000
BMEP 211.7 @5000

Same everything except order heads with 60cc chambers...
11.4:1 SCR
9.5:1 DCR
RPM HP TQ
2000 154 406
2500 196 412
3000 254 445
3500 326 489
4000 396 520
4500 461 539
5000 520 546
5500 552 527
6000 573 502
6500 567 458
7000 539 405
7500 509 356
8000 432 284
V.E. 103.3% @5000
BMEP 215.3 @5000
400+ ft/lbs from 1900 to 7100.... 450+ ft/lbs from 3100 to 6600....500+ ft/lbs from 3700 to 6100....

Change back to 10.8:1 SCR and change cam to Comp 12-900-9
http://www.compcams.com/Cam_Specs/Ca...?csid=310&sb=0
8.477:1 DCR
RPM HP TQ
2000 135 355
2500 175 367
3000 223 391
3500 294 441
4000 369 485
4500 444 518
5000 511 537
5500 548 523
6000 579 507
6500 585 473
7000 579 434
7500 567 397
8000 516 339
V.E. 99.6% @5500
BMEP 211.7 @5000

Same cam, raise SCR to 11.4:1
8.935:1 DCR
RPM HP TQ
2000 138 361
2500 178 373
3000 227 398
3500 299 348
4000 375 493
4500 451 526
5000 520 546
5500 558 533
6000 589 516
6500 600 482
7000 591 444
7500 581 407
8000 533 350
V.E. 100.3% @5500
BMEP 215.2 @5000

Same as above except bolted on a Victor Jr.
RPM HP TQ
2000 128 337
2500 174 365
3000 218 381
3500 287 430
4000 362 476
4500 436 509
5000 497 522
5500 546 521
6000 580 507
6500 599 484
7000 606 455
7500 599 420
8000 558 366
V.E. 100.1% @5500
BMEP 205.9 @5000
As expected, the single plane intake makes more hp above 6500, but gives away torque under 6500.

AFR all the way. Either 180 or the new 195's will make a 383 howl. I have their older 190's on my 383, and I am very pleased. IMO, tlhe 195's would be the way to go.

Every engine on the planet must like AFR's and high compression!!!!!

The fourth test with the 11.4 SCR and looks like it would offer some more then acceptable street performance levels for horsepower, but the 2nd test with the 11.4 SCR, 60 cc chambers, and the 12-702-8 grind really makes some great torque numbers up to 7,000 revs and big horse numbers beyond that....

Looks like a 3500 rpm launch with shifts at 7,000 should make for a good strong pulling small block....

Thanks for the specs and input everyone....Looks like AFR 195's are the way to go.... just wondered if anything bigger was necessary, guess not.... anyway, thanks a bunch!!!!

It gets even better. I just realized I ran those DynoSims with gasoline. Changing the fuel to ethanol gives these results.....

11.4 SCR with 12-702-8 cam.....
RPM HP TQ
2000 168 441
2500 212 446
3000 273 479
3500 345 517
4000 412 541
4500 474 554
5000 528 555
5500 554 529
6000 576 505
6500 571 461
7000 543 407
7500 513 359
8000 436 286
V.E. 104.2% @5000
BMEP 218.6 @5000

Wow, looks even better now Tech!!!!! When I get the short block in hand, I'll have to do some really close checking to make sure we can match the Dyno Sim specs on SCR and DCR.... Got some questions on the heads, but I'll save them till i do a bit more studying... Definitely the AFR's, but there's some options to consider when I order them!!!!!

Talked to Andy (chassis dyno and E-85 carb guru on the drag stuff) and his only concern was making sure the intake manifold would be compatible with the heads. I run a Team G with a turtle and some match porting (to the AFR's) on the Mustang. On the 408 Windsor with a 2" Phenolic spacer it makes good numbers....Surprisingly when we first put the 'horse together and dyno'd it at Andy's, we lost a bit of top end HP but more then made up the differences with mid (3,000 to 7,000 revs) rpm torque gains.... Wondering if the same pattern would show itself on a 383 chebbie????? Team G has always been a good intake for the Windsor's, what do the chebbie strokers like best?????

Any opinions on why the E-85 vs. gas shows as more hp gain then torque gain???? Maybe tip the can about 5% to get a bit more significant gain, huh?????

Dave, it all depends on where you're gonna operate the motor MOST OF THE TIME. On a typical hot street motor where you'll use a cam that makes power from 3000 to 6500 and use maybe a 2800 to 3000 stall converter (yeah, I know you're a 3-pedal kinda guy ), the motor will make more torque with a high-rise, dual-plane such as the RPM or Stealth. It makes little sense to use a single-plane that makes a little more power starting at 6000, but less torque 3000 to 6000, if your rev limit is 6500.

Now, if you're building a race motor and using a cam that makes power 5000 to 8500 with a 5000 stall converter, then it makes little sense to use a HRDP that starts to choke off at 6000.

It's all about using components that will maximize area under curve for the intended purpose.

As you're well aware, that's why we bang on these kids about the COMBINATION.

When I DynoSim'd your combination, I used a fairly short cam because you indicated this is basically a street motor and I wanted to keep it just a little bit tame so that the car would drive a little easier and also to build max torque down low so that when you grab a lower gear and wood it, the torque would be there to turn the car sideways.
Also, as you know, E85 will tolerate 15:1 SCR easily, so I used a cam that makes a very high DCR figure that would be well tolerated on that fuel.

Now, if you want to give me another set of operating guidelines, I'll plug everything in accordingly and we'll see what happens.

Originally Posted by techinspector1

Dave, it all depends on where you're gonna operate the motor MOST OF THE TIME. On a typical hot street motor where you'll use a cam that makes power from 3000 to 6500 and use maybe a 2800 to 3000 stall converter (yeah, I know you're a 3-pedal kinda guy ), the motor will make more torque with a high-rise, dual-plane such as the RPM or Stealth. It makes little sense to use a single-plane that makes a little more power starting at 6000, but less torque 3000 to 6000, if your rev limit is 6500.

Now, if you're building a race motor and using a cam that makes power 5000 to 8500 with a 5000 stall converter, then it makes little sense to use a HRDP that starts to choke off at 6000.

It's all about using components that will maximize area under curve for the intended purpose.

As you're well aware, that's why we bang on these kids about the COMBINATION.

Yup, the combination......and I hate comprimise, too which makes the combination even more difficult!!!! My intended use would be some serious Saturday night action, a bit of bracket and or grudge racing, then a big for sale sign so I can get on to other projects!!!!!

I like clean and crisp throttle response right up to 7,000 rpm....which would seem to be the "max effort" shift point on your last Dyno Sim..... It's a 4340 lightweight (44 pound) crank with 4340 H-beam rods....have to weight to get the blueprint sheet to get actual rod and piston weights I guess. The 'maro will be light....have to get some suspension nailed under it to set it up on the scales and get some front/rear weights, but by my calculations based on weight removal, it will be in the 2700 pound range.....which for an old 3 pedal guy like me spells out aluminum flywheel and "close" gear ratios in the trans with 4th being 1:1 and fifth probably a .72 overdrive..... Rear end ratio is "adjustable"....a few center sections around with ratios from 3.70's with a Detroit Locker to 6.50's on a lightweight spool!!!!

Daily driver and streetability aren't really a significant issue for the car....Bullet fast with slot car like handling is!!!!! Heck, maybe one of these chebbie guys will come by with a great big check and I won't have to worry about it at all, and can just move on to, well, that "other project" we've been talking about!!!!!!!

Originally Posted by tango

The best running SB 383 Chevys that I have seen use AFR 195cc Heads .

You'd better like them, counting on you or one of the other chebbie guys to buy the dang thing when it's done!!!!!! Got to get back on my Blue Oval projects!!!!!!!

Had a long chat with my carb guy today, he's doing me up an E-85 carb based on a 750 double pumper, when done it will flow 830 CFM and have all the necessary mods to work on E-85 (or E-90) on track days...

Now, the next question is of course the intake.... I keep looking at a Weiand Team G, I think the number is 7530. The manufacturer rates this as a 2800 to 7200 rpm intake, perhaps a couple hundred more revs both top and bottom when properly match ported to the heads..... My question is, good choice, bad choice, what might be better????? The rpm range, though high, is where the engine on the sim dyno makes peak power---whatcha think?????

Originally Posted by Dave Severson

You'd better like them, counting on you or one of the other chebbie guys to buy the dang thing when it's done!!!!!! Got to get back on my Blue Oval projects!!!!!!!

I do Like this Build I would Like to see it 80% Strip Car 20% Street . 10.5.1 C/R with the Smaller 550" Roller Camshaft 3800 Stall 4.30 Gear . Team G #7532 with the 3/4" Raised Plenum . That one goes (2800-7800) 750 Holley Race D/P . That car is Light with Big Rear Tire's it will Hook and Flat out Run No Spray Needed

hmmm...was wondering about that one. the compression will be higher then 10.5 because of the E-85 fuel, and stall is not a consideration because this will of course be a 3 pedal car with a five speed!!!!--Weight will also be considerably less then stock, anxious to get the suspension put together now and set it on the scales....