Mike Drew, Dave McLain and I spent a day on the dyno recently, testing Mike's
new 408C engine. Specs of Mike's engine are:
Bobby Oliver (Competition Carburetion in Nevada) modified 750 CFM Holley double
pumper with electric choke
Blue Thunder dual plane aluminum intake manifold
CHI-4V aluminum heads, unported
2.19" intake and 1.71" exhaust Manley Severe Duty valves
1.73:1 ratio stainless roller rockers (Norris or Crower)
Ford 4 bolt main cast iron 351C block
SCAT 408C stroker kit (4-351C-4000-6000):
4340 forged steel crank, 4.0" stroke, nitride hardened
SCAT H-beam forged steel rods, 6" long, SBC journal
Probe forged pistons, 16cc dish, 2618-T61 aluminum , full floating,
1/16", 1/16", 3/16" rings, 1.2" CH, 435 grams w/o pin, p/n 14213-030
Snout spacer (made by Dave McLain)
Powerbond 9000 Series SFI balancer
Pete Jackson quiet gear drive
FRPP M-6500-S58 "Early Block Hydraulic Roller Lifter Set"
10:1 compression
408 cubic inches (4.03" bore by 4" stroke)
Trend custom length push rods
PMGR starter (Dennis Quella)
Aviad Pantera gated and baffled road race oil pan
Aluminum water pump (Dennis Quella modified with backing plate)
Euro GTS Pantera headers with Mike Drew-modified ANSA mufflers
The above specs are how the engine will be installed in Mike's Pantera. On the
dyno, a Holley HP950 carb was used, along with long tube headers and Magnaflow
mufflers. The 950 in HP950 is misleading. It's actually a 750 body with an 850
baseplate and flows around 830 CFM. No intake bellmouth was used on the dyno
carb. The headers used were Hooker Competition headers of 1 3/4" diameter by 27"
long primaries with 3" diameter by 8" long collector (part number HOK-6920HKR).
12 inch long collector extensions and 3" inlet/outlet Magnaflow mufflers completed
the dyno exhaust. We had an Innovate LM1 wide band O2 sensor plumbed into the
header to keep an eye on the air-to-fuel ratio.
Mike had some set ground rules for the engine. First he wanted to use the Blue
Thunder intake manifold he had milled flat to fit under the stock Pantera engine
screen. Retaining the engine screen would also mean no spacer could be used.
The 4V port size of the Blue Thunder intake dictated using either iron 4V or
aluminum CHI 4V heads. Mike chose the CHI heads from Australia. This was to be
a best bang-for-the-bucks build so Mike wanted to use as many of the parts as he
could from his previous poorly matched 351C. For instance, the CHI 4V heads were
purchased bare so we could re-use the Manley valves that were in his open chamber
iron 4V heads. Other parts Mike provided include steel roller rocker arms, guide
plates, oil pump, gear drive, starter, gear drive, miscellaneous fasteners, aluminum
flywheel and an aluminum water pump. Mike also intends to use the gutted Euro GTS
mufflers we previously tested. This would figure into the cam selection.
The block is one I purchased from Steve Liebenow in 1997 when I carried two
complete 351C's in the back of my lowered 1987 Mustang GT from San Francisco to
St. Louis. The block has 4 bolt mains and was standard bore but had damage in
one bore which required a sleeve and some rust pitting in other bores. The block
was sonic tested, bored 0.030" over and honed with a torque plate. Mike chose a
SCAT 408C stroker kit to go with the CHI 4V aluminum heads and Blue Thunder intake
manifold. All engine assembly, along with the dyno services and intake porting
were provided by Dave McLain of McLain's Automotive in Cuba, MO. A few pictures
of the short block and heads are at:
http://s40.photobucket.com/alb...0Cleveland%20Engine/
Mike's based in California where 91 octane is the normal premium pump gas and Mike
wanted to go conservative on the compression. He also wanted to go with a set and
forget hydraulic roller cam. The cam was to be a street grind that would work well
at track days, peaking around 6000 RPM and giving the best area under the horsepower
curve, given the ZF 5 speed gear ratios. I ran the numbers and figured he'd drop
back to around 4000 RPM on shifts and designed the cam to give the best area under
the HP curve between 4000 and 6000 RPM. I could have gotten better peak HP but at
the expense of area under the curve and low end response. Given Mike's exhaust and
carb choices, the cam chosen was a better all around compromise.
Dave flow benched the unported cylinder heads:
Lift Int Exh
0.025 14.1 10.5
0.050 33.3 27.5
0.100 65.7 60.2
0.200 129.5 115.7
0.300 186.2 150.8
0.400 240.5 181.7
0.500 287.5 199.0
0.600 317.5 212.5
0.700 329.6 221.7
0.800 323.0 230.9
and I measured the intake, heads, headers, etc. to feed Dynomation the required
information so I could design the cam using the Pro Iterator feature in Dynomation.
The resulting figures were crossed against Bullet's CRA hydraulic roller lobes.
The CRA lobes have a conventional nose (as opposed to a dwell nose designed for a
lift-rule race class), a lobe shape good for RPM and/or high lift rockers (applies
to the 351C's 1.73:1 rocker ratio and large heavy valves) and an asymmetrical
opening/closing shape (helps with valve bounce). I'll go into more detail on using
Dynomation to design a cam when I post on the cam I designed for Orville Burg (See
"A geek engineer designs a cam"). The resulting cam is a hydraulic roller with
specs:
236/240 degrees @ 0.050" (291/297 deg adv), 0.616"/0.596" lift, 108 LSA
using Bullet hydraulic roller lobes HR291/356 (intake) and HR297/344 (exhaust):
Master Adv .050 .200 Lobe 1.73:1 Lash Type
HR291/356 291 236 156 .3560 .6159 .000 CRA
HR297/344 297 240 156 .3443 .5956 .000 CRA
The Bullet cam core is 1010 steel and requires a compatible distributor gear.
The Crane/FRPP gears were in short supply but Mike found one at Precision
Proformance. Supposedly, the gears are back in production and will be more
widely available soon. Some 351C blocks can use the less expensive OEM Ford
hydraulic rollers with a standard base circle cam but many blocks cannot. It
depends upon the size of the chamfer at the top of the lifter bores. The Crane
p/n 36532-16 link bar retrofit roller lifters will work in all 351C blocks and
can support higher RPM than OEM lifters. The FRPP p/n FRPP M-6500-S58 "Early
Block Hydraulic Roller Lifter Set" are identical to the Crane lifters but were
a bit less expensive when Mike purchased them.
The forged SCAT 351C cranks are made to Ford SVO specs and are essentially
351W cranks with 351C main bearing dimensions and SBC rod journals. The crank
will drop right into a 351C block but a snout spacer is required to compensate
for the 351W dimension snout. The FRPP part is obsolete so Dave McLain made
one for Mike's engine. H-beam rods came with the SCAT stroker kit and fit
without any clearancing.
The engine had been previously run in for around an hour to seat the rings and
several pulls made to determine the best overall timing. An earlier 408C we
tested with iron 4V heads made it's best power at 32 degrees and the 351C dyno
mule made best power at 38 degrees but, with the CHI aluminum heads, Mike's
408C made its best power on only 28 degrees total timing.
Out of the box, the Blue Thunder dual plane intake has 4 runners that flow
relatively well and 4 that flow relatively poorly. The Ford aluminum dual plane
(Boss 351 copy with Holley carb pattern) also exhibits this characteristic, though
the pattern of good and bad runners is different. When we did Glen Hartog's 408C
with iron 4V heads, the bare heads flowed 322 CFM at 0.6" lift. When the dual
plane Ford was bolted up, half the runners flowed in the 270's to 280's, while
the other half were down in the 250's. To equalize the flow in the runners, the
center plenum divider was cut down and the port plenum entry radiused to bring
the poor flowing ports up to match the good flowing ports. On the Ford intake,
a one inch spacer was also used. However, on the Blue Thunder, no spacer was
used to allow the most room for a decently sized drop base air cleaner. The carb
pad had been previously milled flat since the Pantera, unlike most front engine
cars, mounts the engine level. On the previous Blue Thunder (standard version
with canted carb pad), after the plenum work, a typical "bad" runner went from
250 CFM to 276 CFM so the improvement is substantial.
On Glen's 408C, the unported Blue Thunder was down 31 HP and 23 ft-lbs to the
ported Ford dual plane. A Strip Dominator (with 1" spacer) made 15 HP more at
peak than the Ford so the unported Blue Thunder was down about 47 HP to the
Strip Dominator. On Mike's 408C, the ported Blue Thunder and Strip Dominator
were very close with the unported Blue Thunder intake lagging by maybe 15 HP
(see dyno results below). There are several differences that may account for
the better performance of the unported Blue Thunder this time around.
1. Mike's ported Blue Thunder has a flat pad which may harm the wet flow
characteristics of the manifold.
2. Mike's ported Blue Thunder has no spacer. The previous Strip Dominator
and Ford intakes were tested with several 1" spacers. We've seen 10+ HP
with the right spacer (varies from intake to intake).
3. Glen's 408C used iron 4V heads and Mike's used CHI 4V heads. The CHI port
entry shape is quite different than that of the iron heads and may be better
suited to the Blue Thunder intake runners.
4. Some intakes are more combination sensitive than others and I designed
Mike's cam to work best with the dimensions of the Blue Thunder intake.
Dave developed the intake on the flow bench without a spacer and subsequent
dyno testing showed the intake made the same power with or without a spacer.
In addition to the Blue Thunder dual plane, we had several other intakes lined
up to test:
Holley Strip Dominator single plane
Offy 360 Equal Flow split plenum
Edelbrock Scorpion single plane
CHI 3V 4150 single plane
Ford Motorsport A331 high port single plane
Edelbrock Performer RPM Air Gap 2V dual plane
Edelbrock F-351 4V dual plane
Bud Moore Maxi Plenum
Dual Autolite Inlines on Doug Nash IR manifold
Unfortunately, the CHI 3V and Ford Motorsport A331 intakes have raised intake ports
and would not seal against the lower opening of the CHI 4V heads and the Autolite
Inlines required debugging we didn't have time for. In any case, Dynomation
predicted in the neighborhood of 520 HP at 6000 RPM for the Blue Thunder intake
equipped engine, through the mufflers. Initial pulls to set timing resulted in
corrected numbers of 519 HP @ 5900 RPM and 498 ft-lbs @ 4900 RPM, also through the
mufflers. With both the single and dual planes, peak torque was 500 ft-lbs or more
with a wide flat torque band. The lowest RPM pulled from was 3000 RPM and the
engine was making in the range of 450 ft-lbs at that RPM. Those numbers were with
heat soaked intakes. We also tested the Blue Thunder and Edelbrock Scorion intakes
after they had cooled and they were in the 525+ HP range.
Dynomation predicted the Scorpion and Strip Dominator single planes would be close
to the Blue Thunder but the Blue Thunder would have a slight edge in total area
under the curve. The Edelbrock Performer Air Gap 2V was predicted to be not too
far behind, trading some HP for more torque. The Offy was predicted to be the
worst intake with the Edelbrock F-351 4V dual plane somewhere in the middle, falling
off the pace after 4500 RPM or so. The dyno results are listed below and track the
predictions well. As in previous dyno tests, Dynomation's prediction is pretty close
on the peak HP but optimistic by 20 to 30 ft-lbs on the peak torque. Note there are
a few missing tests below. We had an intermittent ignition problem that negated several
tests. Eventually, the fault was traced to the timing controller so Dave bypassed that
and set the timing manually.
I've got the data listed below plotted in an Excel spreadsheet and will post a jpeg of
it later. Comments are ones made when the engine was on the dyno.
Blue Thunder Jetting test
Still running with the HVH spacer but came down two jet sizes from 78 front 90 rear
(no power valve rear) to 76 front and 88 rear. Seemed to help very slightly near
the top end and engine made 522 at 5950rpm.
RPM HP Torque (ft-lb)
4000 374 492
4100 390 496
4200 398 498
4300 409 499
4400 420 501
4500 430 501
4600 441 503
4700 452 505
4800 457 500
4900 464 498
5000 473 496
5100 480 495
5200 489 494
5300 497 493
5400 501 488
5500 502 480
5600 504 473
5700 507 467
5800 513 464
5900 521 463
5950 522 461
Running with no spacer, 76 jet front 88 rear. Took engine to 6200 RPM and power is about
the same at peak with 519 at 5900 RPM.
RPM HP Torque (ft-lb)
4000 371 483
4100 378 485
4200 391 487
4300 402 491
4400 411 491
4500 419 489
4600 429 489
4700 441 492
4800 454 496
4900 464 497
5000 472 496
5100 479 494
5200 486 491
5300 493 488
5400 497 484
5500 500 477
5600 502 471
5700 505 465
5800 514 465
5900 519 462
6000 516 451
6100 508 438
Day 2 Testing
Test 1 Blue Thunder (ported)
Baseline pull for today good pull with a small misfire in the middle of the pull, I think
a plug was loaded a little because we did some messing around warming up the engine. Same
as Test 9 from previous day, 28 timing, 76 and 88 jets in 950HP straight (no spacer) on
the Blue Thunder intake.
RPM HP Torque (ft-lb)
4000 369 483
4100
4200 391 489
4300 403 492
4400 414 494
4500 425 496
4600 436 497
4700 447 499
4800 458 501
4900 464 497
5000 462 485
5100 464 478
5200 478 482
5300 488 483
5400 498 484
5500 505 481
5600 503 473
5700 504 465
5800 511 463
5900 519 462
6000 526 460
6100 507 437
Test 4 Holley Strip Dominator, no spacer
Baseline pull with the Stip Dominator intake manifold. Seems as though there is
not much difference between the two intakes right now but I need to go back to
the 90 and 78 jet.
RPM HP Torque (ft-lb)
4000 369 482
4100 372 477
4200 385 480
4300 395 482
4400 403 481
4500 413 482
4600 423 483
4700 435 486
4800 449 490
4900 456 490
5000 465 488
5100 471 485
5200 476 481
5300 483 478
5400 490 477
5500 496 474
5600 492 461
5700 492 454
5800 496 450
5900 504 448
6000 508 444
6100 497 429
Test 5 Holley Strip Dominator
Back to the stock jetting in the 950HP and power picked up a little with the Strip
Dominator.
4000 370 481
4100 376 479
4200 386 483
4300 395 483
4400 401 480
4500 410 479
4600 421 481
4700 434 485
4800 447 488
4900 457 490
5000 466 490
5100 484 495
5200 486 493
5300 490 486
5400 496 483
5500 500 477
5600 496 466
5700 495 456
5800 502 455
5900 513 457
6000 518 454
Test 7 Edelbrock Performer RPM Air Gap 2V
Fixed ignition glitch and found some torque and HP. This intake is down about 12 to 15
horsepower right at the top above about 5500 RPM but is superior down lower. Might be
the best all around compromise for the Cleveland but won't fit under the Pantera engine
screen.
RPM HP Torque (ft-lb)
3900 383 512
4000 387 509
4100 396 508
4200 408 509
4300 416 509
4400 425 508
4500 435 507
4600 445 508
4700 451 505
4800 466 507
4900 466 500
5000 468 492
5100 474 488
5200 481 485
5300 484 480
5400 487 473
5500 489 467
5600 487 457
5700 490 451
5800 495 448
5900 501 446
6000 494 432
Test 8 Edelbrock Scorpion
Edelbrock Scorpion intake with 950HP. Seems to be very good for torque and HP when compared
to baseline or anything else. Good solid torque and HP across the board. Will not fit on
Pantera but this intake does have a level carburetor pad.
RPM HP Torque (ft-lb)
4000 390 507
4100 393 505
4200 403 505
4300 414 505
4400 423 505
4500 433 505
4600 446 508
4700 457 511
4800 464 508
4900 473 507
5000 480 504
5100 486 501
5200 492 497
5300 499 495
5400 504 491
5500 507 484
5600 505 473
5700 507 467
5800 509 461
5900 516 460
6000 525 459
Test 9 Backup of Scorpion
Allowed intake to heat soak and did a pull from 3000 rpm. After a good heat soak, intake
produced more realistic power levels very much inline with our baseline with the Blue Thunder
intake. The Scorpion is essentially a Torker with an intergral spacer and level carb pad.
The Scorpion works better on this engine than the Torker with spacer did on Glen's 408C.
RPM HP Torque (ft-lb)
3000 253 440
3100 257 437
3200 265 435
3300 272 436
3400 291 445
3500 299 449
3600 308 451
3700 320 454
3800 334 462
3900 350 471
4000 366 480
4100 380 487
4200 393 491
4300 405 494
4400 416 497
4500 428 500
4600 442 503
4700 451 505
4800 459 503
4900 466 499
5000 474 498
5100 480 495
5200 487 492
5300 499 494
5400 503 490
5500 504 481
5600 503 472
5700 504 464
5800 507 459
5900 511 455
6000 510 446
Test 10 - Offy 360 EquaFlow
Started pull at 3000rpm as on the previous test. Engine sounded ok but power is off
somewhat with this intake as expected. Down 30+ horsepower or so from the baseline.
RPM HP Torque (ft-lb)
3000 244 427
3100 252 428
3200 261 428
3300 270 430
3400 279 432
3500 289 434
3600 299 436
3700 309 438
3800 319 440
3900 329 444
4000 342 449
4100 354 454
4200 366 458
4300 381 465
4400 394 471
4500 404 471
4600 413 473
4700 423 473
4800 432 473
4900 442 473
5000 445 468
5100 447 460
5200 448 453
5300 453 449
5400 458 445
5500 457 436
5600 455 426
5700 456 421
5800 461 416
5900 466 415
6000 467 408
Test 11 - Edelbrock Performer F-351 4V with 1" 4 hole spacer
Running from 3000rpm with the Performer intake and it works as expected, good torque
at peak but torque falls quickly past about 4500rpm. Wonder how well it would work
given the plenum treatment the Blue Thunder received?
RPM HP Torque (ft-lb)
3000 264 461
3100 261 443
3200 272 447
3300 284 453
3400 298 460
3500 311 467
3600 324 473
3700 337 478
3800 349 482
3900 360 485
4000 372 488
4100 384 492
4200 395 494
4300 405 495
4400 414 494
4500 424 495
4600 434 496
4700 438 490
4800 444 488
4900 457 488
5000 460 485
5100 462 476
5200 466 471
5300 474 469
5400 477 464
5500 478 457
5600 474 444
5700 472 435
5800 475 430
5900 480 427
6000 479 419
Test 12
Bud Moore box intake with 4 hole 1 inch spacer. Did not run particularly well and
seemed to have rather weird changes in mixture with the wideband from about 11:1 to
very lean and back again randomly through the pull. Fuel puddling was evident when
the top was removed.
RPM HP Torque (ft-lb)
3000 253 440
3100 258 438
3200 268 439
3300 278 442
3400 288 445
3500 299 449
3600 316 458
3700 328 466
3800 344 476
3900 358 482
4000 368 484
4100 380 487
4200 391 489
4300 402 491
4400 415 495
4500 426 497
4600 436 498
4700 444 496
4800 453 495
4900 459 492
5000 464 487
5100 469 483
5200 476 481
5300 481 477
5400 485 471
5500 486 464
5600 483 454
5700 480 442
5800 484 438
5900 486 432
6000 481 421
Test 13
Testing with a stock BT intake with no porting work. Made good power, about 497 HP at 6000rpm. After a reasonable
amount of heat soak time.
RPM HP Torque (ft-lb)
3000 257 448
3100 263 446
3200 274 449
3300 284 452
3400 295 455
3500 307 461
3600 324 470
3700 335 475
3800 347 479
3900 357 482
4000 368 483
4100 379 485
4200 391 489
4300 404 492
4400 414 495
4500 424 496
4600 438 495
4700 440 492
4800 442 483
4900 449 481
5000 456 480
5100 464 477
5200 469 474
5300 477 472
5400 476 464
5500 477 454
5600 474 445
5700 473 436
5800 479 434
5900 488 434
6000 497 435
6100 469 405
Test 14 Back to Ported Blue Thunder
Went back to the modified BT intake with ported and milled plenum. Made similar power but
we had changed jetting so power was down a little.
RPM HP Torque (ft-lb)
3000 247 434
3100 255 431
3200 263 432
3300 273 434
3400 283 437
3500 294 441
3600 306 447
3700 320 454
3800 334 462
3900 348 469
4000 360 472
4100 373 478
4200 385 482
4300 398 486
4400 409 488
4500 420 490
4600 429 491
4700 440 492
4800 451 493
4900 460 493
5000 464 488
5100 470 484
5200 477 481
5300 482 477
5400 487 473
5500 490 468
5600 490 459
5700 492 454
5800 496 449
5900 501 446
6000 509 445
Dyno Dan Jones
Original Post
