Atilla the Fun

Atilla's Best Builds:
Guys, here's my collection of the best engine combos I've ever found.
In each one, I'll give you the dyno results, and I'll list as much as I can
of what it takes to get those dyno results. These builds are great
because in each case, they give excellent torque curves for the price,
AND excellent torque curves considering both the cubic inches and
type of intake manifold.
Every one is naturally aspirated and runs on premium pump gas.
If you deviate AT ALL from the parts listed, your results WILL be LESS.
In each case I'll comment on the emissions aspect.
When something wasn't specified, either the info wasn't available to me,
or your choice won't affect the results. Most of the stuff not specified
won't affect the results either.
So far I have prepared builds for each of these engines, more will follow.
Carbureted, quasi-legal 350
Carbureted, not-legal 383
Carbuteted, legal 383
Injected legal 383 high-revving HP
Injected quasi-legal 350 low-revving TQ
Injected legal 383 low-revving TQ
Carbureted, not-legal 400
and if I get enough requests, I'll do some 496 big blocks.
I've also got another 350 and another 383 to add. I've mis-filed the dyno
sheets, but I do recall that the 350 gives 425 HP around 6000 rpm using
Edelbrock heads and RPM intake, COMP DEH275H10 cam, and the 383 had
511 ft-lbs at 2800 rpm from a Performer RPM, a COMP DEH265H10, flat-top
pistons, and 64cc Sportsman 2s with 2.055" intake valves and extensive bowl
work.

Atilla the Fun

Carbureted 350
This 350 is notable for making 385 ft-lbs from 2600 to 5400.
That's better than GMPP's FB385 does at it's peak. And this
is so much cheaper, despite being all GM, except for the
intake manifold. Of course headers must match
your car, but this was tested with 1.625" long-tubes. So for
third gens, that means Hedman.
Best of all, this runs on regular unleaded, it has dished pistons.
To copy this, you'll need the following parts:
GM p.n. 12530282 crate engine, or junkyard equivalent
Edelbrock p.n. 7516 intake manifold
GMPP HOT cam kit, p.n. 12480002
competitionproducts.com p.n. 4718 cutter
" 4732 arbor
Fel-Pro 1094 head gaskets
and your choice of 750-cfm carb.
For that you get these dyno results:

RPM TQ HP

2600 385 191
2800 392 209
3000 399 228
3200 409 249
3400 419 272
3600 425 291
3800 425 307
4000 425 323
4200 428 342
4400 425 356
4600 420 368
4800 415 380
5000 407 387
5200 397 393
5400 385 396
5600 375 401
5800 360 397
6000 338 386

The Hedman headers run from the plain $223 p.n. 68460 to the
$659 fully coated p.n. 66469 offerings.
You can get another 10 horses by polishing the exhaust ports.
And yet another 10 by switching valves to these
: http://www.competitionproducts.com/S...ductinfo/8430/ ,with
30-degree back cuts from your local machine shop.

Atilla the Fun

Carbureted 383
This 383 has great bang for the buck. Check the torque curve.
Then I'll list what is required to get these results.

RPM TQ HP

2400 426 195
2600 438 217
2800 445 237
3000 453 258
3200 465 283
3400 477 308
3600 483 331
3800 483 350
4000 483 368
4200 486 389
4400 483 405
4600 478 419
4800 471 430
5000 461 439
5200 451 446
5400 437 449
5600 420 448
5800 402 444
6000 381 435

Very strong, considering the heads. And notice that this thing
makes more torque from 2600 rpm to 5400 rpm, than the peak
torque of the 350 I just detailed. You didn't skip over it, did you?
The easiest way to do this costs a freakin' fortune, but you can just
buy the GMPP 383 crate engine, with iron Vortec truck heads.
The heads will have to come off to prep them for this cam.
so, here's your shopping list:
GM p.n. 12497317 crate engine
COMP p.n. 12-432-8 cam
" 986-16 springs
" matching retainers
competitionproducts.com p.n. 4732 arbor
" 4718 cutter
Edelbrock p.n. 7516 intake manifold
Fel-Pro p.n. 1094 head gaskets
your choice of 750 cfm carb
1.625" long tube headers to match your car. For the third gens,
this means Hedman. The cheapest is the plain p.n. 68460 for $223,
and the fully coated version is p.n. 66469 for $659.
This build can also be run on regular unleaded with no worries.
Want more HP? Want it enough to buy better heads? Look here:

2500 431 205
3000 453 259
3500 485 323
4000 495 377
4500 500 428
5000 486 462
5500 464 486
6000 422 482

That's with TFS 215 cc heads and 1.75" long tubes, such as Hooker's
p.n. 2210-1HKR.
Notice that up to about 3500 rpm, the results are the same. This is
because this cam is limiting torque, not the heads or headers.

Now for the disclaimer: under current federal law, this entire particular
build, as presented, is blatantly illegal for street use in '68-up cars.
So I've also prepared a clean version.
The offending items in this build are the things that give it such a great
torque curve: the cam, intake and headers.
You can get another 10 horses by polishing the exhaust ports, and yet
another 10 by installing a set of these
: http://www.competitionproducts.com/S...ductinfo/8430/ ,with
30-degree back cuts done by your local machine shop.

Atilla the Fun

Carbureted 383
This 383 isn't amazing, but aside from the long-tubes,
should be easily legal in any pre-'88.

RPM TQ HP

2600 424 210
2800 440 235
3000 449 256
3200 454 276
3400 459 297
3600 467 320
3800 470 340
4000 468 357
4200 467 373
4400 468 392
4600 461 404
4800 453 413
5000 440 419
5200 429 424
5400 419 431
5600 398 421
5800 381 421

Just take a dished piston 383, and add Holley's good ol'
300-504-1 top end kit. And some 1.5:1 roller rockers.
This includes aluminum heads that flow 223 / 172 cfm
at 0.500" at 28 in HG. through 2.02 / 1.60" valves.
And the Weiand 8000 intake, and a 216 / 228 at .050"
cam, 112 lobe sep, .454 / .480" It's a hyd. non-roller.
Here, it was installed on a 107 degree intake centerline.
The cam has an E.O. number, and so does the 8000. I
think the heads do also. If not, Edelbrocks will suffice.
In fact, they'd slightly improve the results.
This build was tested with 1.625" long tube headers, such
as Hedman offers for our third gens. For fully coated, pay
$ 659 for p.n. 66469, or for plain, pay $ 223 for p.n. 68460.

Atilla the Fun

TPI 350
This is the torquiest 350 ever. It's TPI. And with a little work it can
be made emissions legal. Just add the external EGR kit from SD.
It out-torques many 383s, and offers more MPG, too!
Now, here's the results, then what it takes to make them.

RPM TQ HP

2400 423 193
2600 442 219
2800 458 244
3000 459 262
3200 472 288
3400 475 307
3600 468 321
3800 478 346
4000 487 371
4200 479 383
4400 469 393
4600 458 401
4800 450 411
5000 437 416
5200 415 411
5400 389 400
5600 367 392
5800 350 387
6000 338 386

This was done using all of the following :
A 30-over 350 with flat top pistons
poorly ported iron Vortec L31 Chevy truck heads
COMP 08-304-8 cam
SD Vortec TPI base
Accel large tube runners
Accel 58 mm TB
24 # injectors
43 psi of fuel pressure
93 octane pump gas
1.75" long tubes such as Hooker 2210-1HKR
2.5" dual exxaust with FlowMaster mufflers :-(
MSD coil
And I suggest you use 1.50:1 In / 1.60:1 Ex roller rockers
Properly geared, this'll run low 12s at sea level.
And spank a peanut-port 454 with intake, cam, and headers.

Atilla the Fun

TPI 383
This 383 is simply amazing.

RPM TQ HP

2600 410 203
2800 430 229
3000 475 271
3200 503 306
3400 506 328
3600 514 352
3800 527 381
4000 531 404
4200 524 419
4400 515 431
4600 502 440
4800 487 445
5000 472 449
5200 449 445
5400 432 444
5600 417 445
5800 408 451
6000 400 457
6200 387 457

This is Tuned Port Injection at it's very best. Start with a set
of pistons with about 18 cc of dish volume.
Send some ZZ4 heads to Extrude-Hone, along with the stock
TPI base and plenum.
This build came in at 10.6:1.
The shopping list includes:
TPiS large tube runners
36 # injectors
COMP XR264HR10 cam
electric water pump
pair of 3" Magnaflow mufflers
58 mm TB
long tube 1.625" headers, such as Hedman offers.
p.n. 68460 for plain versions at $223, or for fully coated versions,
p.n. 66469 at $659.
1.5:1 rockers were used.
You'd have no trouble at all getting this build through emissions
inspection, even in California, if it weren't for the long-tubes
preventing you from putting the cats in the stock location.

Atilla the Fun

EFI 383
Here's an emissions-legal EFI 383 that gives very LSx-like results.
This one is lifted directly from TPiS, but it is very impressive. A few
guys on here don't like TPiS, but I've enjoyed great service and
great quality products from them. And I've never seen any other SBC
make so much HP from such a small exhaust lobe. Amazing!

RPM TQ HP

2200 409 171
2400 414 189
2600 417 206
2800 419 223
3000 431 246
3200 442 269
3400 446 289
3600 447 306
3800 445 322
4000 445 339
4200 453 362
4400 465 390
4600 479 420
4800 487 445
5000 487 464
5200 486 481
5400 474 487
5600 470 501
5800 453 500
6000 436 498
6200 419 495
6400 406 495
6600 388 488

This was done with the Mini-Ram intake, the ZZ409 cam, 1.6:1 rockers,
a 52mm TB, 11:1, and their version of the AFR heads. they didn't specify
which headers, but I'd suggest that you'd get best results from using
Hooker's p.n. 2210-1HKR.

Atilla the Fun

Carbureted 400
For those who can find a useable 400 small block, and can also
afford to top it well.

RPM TQ HP

2000 410 156
2200 418 175
2400 436 199
2600 460 230
2800 473 252
3000 474 271
3200 474 289
3400 476 308
3600 489 335
3800 501 363
4000 511 389
4200 517 413
4400 521 436
4600 524 459
4800 524 479
5000 517 492
5200 503 498
5400 495 509
5600 485 517
5800 476 526
6000 452 517
6200 441 521
6400 420 512

To copy this, start with a 400 with dished pistons.
This build used the following:
9.5:1 compression
coated-top pistons
COMP 12-000-8, 3017/3038, 110 cam on a small base circle
Dart Pro 1 180 cc heads
Dart dual plane air gap intake
1.5:1 roller rockers
Demon 650 carb
1/2" carb spacer
1.75" long tubes such as Hooker p.n. 2210-1HKR
note that this cam will never pass a tailpipe sniffer.

Atilla the Fun

Edit, Thursday, June 11? 2010.
Five7kid has just asked me to post some advice in here for people who are either running a new stock L31, or a salvaged one, and don't want to pull the heads.
But it's a trick question. If it's a used L31, you have to pull the heads to make sure the heads don't have "the Vortec crack"
L31s tend to develop an issue with coolant leaking from the rear of the engine, where the intake meets the heads. The coolant runs down the bellhousing, and the heat of the exhaust evaporates it away. So you get low on coolant, and the engine overheats. This is what causes "the Vortec crack"
Now, this crack tends to be awfully big. It happens on the deck surface, between the center 2 combustion chambers. It's usually more than an inch long.
Now that the heads are off, go reference the above builds, and my sticky thread on porting SBC heads.
For those who bought the crate L31 engine, ( GM p.n. 12530283, =4BM, or 12530282, =2BM ) but want as much more cam as is safe, here's what to order:
http://www.lunatipower.com/Product.aspx?id=2007&gid=281
And with that, you'll also need better springs. Look at these:
http://www.competitionproducts.com/H...uctinfo/98214/
Use only 1.5:1 rocker arms. Keep the Vortec retainers. Use headers. 700R-4 people hold first gear to 6200 rpm when racing.
Now, if you're considering the crate 330 HP 350; DON'T!!!!!!! It has NO advantages over a crate L31, but it does have a few serious disadvantages. It costs more, it doesn't include roller lifters, it doesn't include any of the corresponding parts that go along with the roller lifters, and if you don't change the cam in the L31, it has a better warranty.

And here's a carb'd 383, 9.4:1, AFR 195 heads, RPM AirGap intake, 1.75" Hooker long-tubes, COMP 08-415-8 cam, Holley 750 HP, 1.52:1 rockers.
2800 397 212
3100 422 249
3300 443 279
3500 459 306
3700 473 333
3800 476 344
3900 481 357
4000 483 368
4100 487 380
4200 489 391
4700 489 437
4800 487 445
5000 484 461
5100 481 467
5200 477 472
5300 473 476
5800 444 490
6100 422 490
6400 397 484

skinny z

Nice collection especially considering I'm in the process of my next build (see 350 kaput!)
A couple of questions regarding the 2nd engine listed. (carbed 383).
I see you've speced a .015" head gasket. In combination with a 64cc head, the static compression will be through the roof with a traditional flat top piston. What volume of piston dish is recommended or better still what is the target SCR and DCR? Is there a piston part number available?
If I stick with my current 12-423-8 cam I know my DCR will be higher still however I can limit this with a slightly thicker head gasket. I understand the implications with respect to the published dyno numbers however will the increased quench ruin some of the efficiency?
Thanks for the info.

Atilla the Fun

Summit has a good deal on some 17.8 cc dished hypereutectic pistons, they're going for $160 / set. These will work fine.
Never ever choose head gaskets based on SCR. Choose head gaskets based on quench. The goal is 0.040"-0.045". If you go with the Summit pistons and an un-decked block, then www.competitionproducts.com has a good deal on some 0.025"-thick head gaskets for $10 each under CP part number HG31600.
Those of you at high elevation, like in Denver, should be finding 12 cc pistons, as offered by Speed Pro and Keith Black. And Speed Pro also offers 12 cc dished forgings. With any Speed Pros in an un-decked SBC block, use the Fel Pro steel shims.
If your block has been decked, you can PM me.

skinny z

Thanks for that.
I'd love to get into some specifics about my proposed build (head gasket vs deck height, quench, SCR/DCR) however I'll pursue it either with my own thread or via PM.
Thanks again.

Stephen

iTrader: (12)

Are these actual, physical builds you have built & dyno tested? Or just Desktop Dyno "builds"?

87WS6

iTrader: (1)

I'm curious about that myself.

one92rs

iTrader: (5)

the first 350 build. i have a 1999 vortec 350 long block in my garage that needs to be rebuilt. 062 heads. i am going to do a 355 and was after flattop pistons. so would the flattops yield more hp or less. what is the compression of this engine. if no flattops then what is a good piston .030 that i could get this power out of. my buddy has those exact headers that i am buying also. and how much hp loss will i have with a edelbrock 2116 manifold as it was givin to me free brand new. and would stock replacement lifters work on this combo as i will have to buy a set. mine have 200,000 on them.

dammit can i just send you my long block and you get it ready for me by christmas??????? i want number 1.

Atilla the Fun

These are legit. No desktop dyno programs for me.

Atilla the Fun

quick note here, I just added more info to the OP.

Atilla the Fun

Flat tops with Vortec heads has been done, by many people, but mostly with cams wilder than this one. And I've yet to see any of them make any real power gains over this one. If you want flat tops with this combo, you'd better live someplace high, like Denver, Colorado. Or LaPaz, Bolivia.
This build was just over 9:1, but I'd prefer 9.5:1 and premium unleaded all the time. If you're building from scratch. I'd suggest 12 cc Keith Black hypers.
The engine will still pull 5500 with Edelbrock's basic Performer Vortec intake, but don't expect to get close to 400 horses.
Any HR lifters will do if you're copying this build.

one92rs

iTrader: (5)

cool!!!!!! i was wanting from 350 to 400hp and 380 to 400tq. so i suppose this will be perfect for me. i will go with the kieth black dish. im not trying to build a race car just something that runs good without having to wring it out to run good. and no i dont live there. i live in south texas.

Atilla the Fun

Unless you're running a 700R-4, this build will give 95% with a 5600 rpm shift point. Most of the time, that'll be enough to put the ricers in their place.

one92rs

iTrader: (5)

darnit i am running a 700r4.

Orr89RocZ

iTrader: (20)

I really want to question that 383 TPI build with extrude honed ZZ4 heads and tpi base stuff. I dont see that combo peaking hp anywhere NEAR 6000 rpm. Thats highly suspect. I'm curious to see what those numbers translate into rwhp on a chassis dyno. 450 hp out of that setup with those small heads/cam seems optimistic to me.

Atilla the Fun

1-2 at 6200 when you need to win.

87WS6

iTrader: (1)

I'm definitely keeping an eye on this thread. You read about performance engines all the time and various builds, but when you are a novice in that department, sometimes you just want to see someone say use these heads, this cam, this EFI setup and you'll get xxx HP and xxx TQ.

88fastgta

iTrader: (9)

atilla about the 350 tpi numbers... i love those numbers...makes my wanna get rid of my stock heads... i have a gm hot cam which is bigger than the comp cam listed but i have stock heads..i basically have the same combo...... shouldnt i be close to those numbers... also are those numbers and the engine or the wheels...

Atilla the Fun

Different heads and different cam = different results. These combos give results so good you doubt them, because everything works together. If you like the dyno numbers, then use the exact parts I specified, the exact way I specified. If you don't like what I listed, don't expect your results to equal these.
I've seen literally thousands of combinations. These are the few that rise above. That give far better results than combos that are very similar.
These numbers are from engine dyno testing. No way you can get these results from these builds on a chassis dyno. Subtract at least 13% for a manual, ans at least 22% for an automatic.
But before you do that, subtract 1% for each 250 feet you live above sea level. At 4500', I have to subtract 18% to correct for the thin air up here. then I can subtract 135 for a manual, to have a close estimate of rear wheel numbers like I'd get from a chassis dyno that wasn't correcting for elevation. Most of them do, but that's not really fair or honest. But most dragstrips also correct too.

one92rs

iTrader: (5)

ok i live at 32 ft above sea level. good for me i guess. the only reason i asked about the 2116 over the 7116 is i have one sitting in the garage brand new with a water stain on it. but since i will be starting from scratch with the 99 vortec in the garage this is the build i was looking for. from what i understand the airgap and the 2116 are the same height right?? if so i may see if i can sell mine to get the airgap. and it has the 062 heads on it.

just found my answer. the air gap is about 3/4 of an inch taller. will not fit with carb and aircleaner under factory hood. so the 2116 will have to work.

and if i figure it right with about a 5% loss due to intake and an auto it would net be about 290 to 300 rwhp and 310 to 320 rwtq. still not to bad. especially over the 170 hp 305 that is in it now.

Atilla the Fun

I suggest you notice that the HP sort of peaks twice. In fact, get you some graph paper, map it out, and see for yourself. When you see the TQ curve, you'll have less trouble believing it.

Atilla the Fun

IDK offhand what the 7116 is, but the 2116 is nothing like the 7516.

one92rs

iTrader: (5)

well if you dont mind.lemme ask a question.
l31 .030 062 heads pocket ported exhaust. hooker longtubes. is there a cam that will give me the 380hp and 400tq. comp specked this cam.
NTAKE MASTER 3314S

EXHAUST MASTER 3315S

ENGINE CS XR276HR-10

GRIND NUMBER CS XR276HR-10


INT EXH

HYDRAULIC Y/N YES DUR @.050 224
230

INT EXH LOBE
LIFT .335 .340

VALVE ADJUSTMENT HYD HYD ROCKER RATIO 1.5 1.5

MAX GROSS VALVE LIFT .502 .510

DUR @ .006 TAPPET LIFT 276 282 LOBE SEPARATION 110.0

ADVANCE
4

VALVE TIMING OPEN CLOSE VALVE SPRINGS 986-16

.006 INT 32 64


EXH 75 27

THESE SPECS ARE FOR CAM(S) INSTALLED

106.0 INTAKE CENTERLINE


will this get me where i want to be.

Atilla the Fun

That's a pretty good choice for an off-the-shelf cam. It'll meet your goals. But it costs more than the GMPP HOT cam. And it has too much overlap to pass a tailpipe sniffer, unlike the GMPP HOT cam.
You'll be giving up a bit of low-rpm torque, but if you're going this way, you're probably using enough rear gear that it won't be a problem. This cam does well with a 2400-stall converter.
This cam does give a slightly racey idle.

Orr89RocZ

iTrader: (20)

I dont need to graph it to see the trend there. What explains the second higher rpm peak? Torque curve is slowly falling from its peak on down past the first hp peak. Over the hundreds of builds i've seen on these forums over the last 7 years I've never seen a TPI based setup that wasnt siamesed support those kind of rpms. The first peak near 5000 is much more in line with a big tube TPI motor. For such a small cam for a 383, I'm just dont understand the second peak at such high rpm. The better head/miniram EFI motor you posted with a bigger cam doesnt even have a peak that high.

one92rs

iTrader: (5)

gm hotcam it is then.

Atilla the Fun

Why is there always one know-it-all who doesn't quite get it and tries my patience? Well, this time I am gonna explain things. First, anyone else would've shut the dyno off at 5200 or 5400 rpm. And you'd've believed those results. Guaranteed. HP is calculated from measured torque times rpm, divided by 5252. And the RPM number rises faster than the TQ falls, unless there is an issue with valve control by the springs. But in this case there was no such issue. The friction isn't the issue. It's proportional. The linear reduction in time in which to fill the cylinders is the reason torque declines. The long tubes of the TPI system are sort of cancelled by the increasing frequency of the intake valves opening. And with such good-flowing induction pieces, there can be no doubt that the cfm is there to support 457 hp.

87WS6

iTrader: (1)

I'm not an engine building expert, but it does seem that Atilla's builds are at least plausible. Don't take my word for it, here are some similar results using a TPI 383 Stroker which is making good power out to even 6,000rpms using ported and extrude honed stock parts.

Atilla the Fun

Actually, I copied that exact one for a customer of mine, and my results were within 2%. That's when I went to the TGO classifieds and posted a WTB to get a stock TPI plenum of my own, which arrived last week. It's the only piece the aftermarket doesn't offer.

Orr89RocZ

iTrader: (20)

I'm not claiming to be a know it all. You are the one posting these builds and I have a question about one of them that doesnt seem to clash with other builds on these forums. I am simply asking for more clarification on this issue and why in fact the TPI long tube runner system that is tuned for 4500-5000 rpm performance is able to create another peak at a MUCH higher rpm considering the cam is rather small for a 383.

I"m not doubting the CFM is there for 457hp, I'm just interested in why it wants to peak again. With the cam being rather small its not gonna beable to fill the cylinders at the higher rpms like a cam with abit more overlap and different valve events suited for higher rpm. With the tuned runners of TPI not clashing well with such high rpm it will make it more difficult to fill cylinders at high rpms. The intake pulses to fill the cylinder are off and with the long length of runner the motor has to suck through, its just going to be difficult to breath at high rpms. Based on these numbers from TPI, I'd be extremely curious how a short runner intake would do on that setup since after 5000 rpm, it would be better suited to provide air at those upper rpms and should dramatically increase power. But then again with the change in runner length the cam is no longer optimal for those upper rpms to take advantage of the short runner tuning. It goes hand in hand. Its just odd to me to see a 212 deg cam peak at those rpms with a 383 motor and TPI. I dont think the heads/intake have the cross sectional area and the cam does not have the duration to support a peak up there. Just looking for insight on this. There may be more power locked up in small cams than anyone realizes.

Jim85IROC

iTrader: (2)

I'm liking that TPI 350 build. The 350 that's in my IROC is getting transplanted into my GTA when I yank it for the 402 LS that's going into the IROC. The motor is currently a poor combination of parts (461 heads with TPI) and I had planned on swapping my SDPC vortec heads on it when it goes into the GTA, but most of what I've been reading indicates that the SDPC/edelbrock vortec TPI base is garbage. It's nice to see some results that refute that.

My only issue is that my motor is a flat tappet motor, so I can't run the same cam. I also won't be running long tubes. Hopefully I can come up with a similar combination that provides similar results.

Here's a question... what are your thoughts on having the SDPC intake extrude honed so that it'll actually flow something? My opinion is that the TPI torque is a function of the runner length, not it's diameter, so opening it up could only help.

Primetime91

iTrader: (15)

I for one, would be very interested in seeing some 496 builds

Kinda scared of what the cost will run on them though

87WS6

iTrader: (1)

I don't know. I'd say that honing the intake could only help you rather than hurt you. What gets me about the build I posted is that they kept the stock runners. They didn't saimese them. They just extrude honed them to flow better. I've got a Vortec 350 block (essentially the same as a ZZ4, but with roller cam provisions, I believe.) and some 906 heads for it. I've been thinking about stroking that to a 383 and keeping TPI on there. I'd also like to add a Procharger to that. Possibly turbo it. Though I'm not exactly sure what I'd need to do all that yet. Its getting much closer to build time for that so I'm really interested in threads like this.

Atilla the Fun

Okay, I was a bit upset earlier, I do apologize for berating you. Please forgive me that.
I don't fully grasp the effects of wave dynamics. I understand that any length of intake runners will have a primary frequency, and a secondary frequency. TPI runners being the length they are, they do produce a strong ramming effect in what we call the mid-range rpm. So there's the primary frequency. We don't have to understand that one to believe it, and to make use of it. And this cam is well matched to that rpm range. That's why we are seeing 531 ft-lbs from just 383 cubic inches.
But it's inevitable that it must produce a weaker ramming effect at some other rpm. That's what we must be seeing at the very top of this pull. Maybe the Mini-Ram would do it if we could spin the build under it to high enough rpm. I suspect so. But SBCs just do not turn that kind of RPM. And even if they did, how many custom cams would we have to try to do what dumb luck did here?
This gives me a headache. I'll get back this evening.

Atilla the Fun

the AFR-headed builds are pricey, but 660 to 730 HP makes a good argument. Here's a couple with the $995/pr (bare) Patriot Freedom heads, in the 600+ HP range, and here's one with ported iron oval ports that's a low rpm torque god. Pick your poison. :-)

Atilla the Fun

Boost with Vortecs is generally ill advised. If you can afford boost, then start with some AFR heads. It's an issue of exhaust port flow. My personal best with Vortec exhaust ports, using good 1.60" valves and every trick I know, gives these results, without any length of header pipe: 0.100" = 57 cfm, 0.200" = 114, 0.300" = 149, 0.400" = 167, 0.500" = 179 0.600" = 185, while AFR's best exhaust port, with a 1.75" pipe, flows like this: 0.200" = 115, 0.300" = 165, 0.400" = 200, 0.500" = 217, 0.600" = 225.
also, dished pistons run too hot. Better to use larger chambers, like AFR's 75cc, with much less dish to the piston. Just better durability. Also, the AFR decks are about twice as thick.
Vortecs are wrong for what you have in mind.

87WS6

iTrader: (1)

This is the kind of advice I was looking for. I had been looking at porting the Vortec's, but wasn't sure if that was the right call. I figured AFR's were the best way to go despite the cost.

one92rs

iTrader: (5)

have a question? the gmpp hotcam kit comes with springs. do the heads need to be machined for the springs in the kit? or would be ok to run the behive springs with the hotcam.

Orr89RocZ

iTrader: (20)

AFter thinking about it more, that may be the case. It may be a secondary wave that enables the peak. Regardless its a strong engine build and should be very fun to drive on the street. Thanks for sharing your builds this is very helpful.

Have you done any 305 builds? The general concensus is it is a waste of time but since 85% of these cars have 305's from the factory, any budget minded setups that make decent power?

one92rs

iTrader: (5)

oh yeah! will flat top pistons in a 1999 l31 with 062 heads net me 10-1 compression? if not what needs to be done to get 10-1.

Atilla the Fun

It's better to run beehive springs if you can afford them.

Atilla the Fun

I have done 305s, but the bottom line is: It's better to swap in a 350 with stock low-output 305 manifolding, than it is to modify the 305. And cheaper. The 350 SHOULD ALWAYS BE THE FIRST MOD. when you factor in the refills, not even nitrous has the bang for the buck of an '87-up 350. (But don't get the 193 heads)

Atilla the Fun

No, you'll be well over 10:1. Fine if you're in Denver, or wanting to run a cam bigger than the GMPP HOT cam, but otherwise just keep the L31 pistons. Do a re-ring job.