what do head flow numbers mean?

grumpyvette

grumpyvette

Administrator
Staff member
I HAD THIS QUESTION POSTED ON A DIFFERENT SITEHEY GRUMPYVETTE??

I need some more lessons. I Can someone explain to me what flow numbers for heads mean?

Here are some numbers from three different heads, they mean nothing to me , yet.

http://www.fastnuf.com/Headguide.html

http://users.erols.com/srweiss/tablehdc ... _Big_Block

http://www.circletrack.com/enginetech/c ... index.html

AFR
195
Eliminators
Valve Size 2.055/1.60
Chamber Size 65cc or 75cc
Intake Runner 195
Exhaust Runner 80
0.100 70.4/56.7
0.200 149.5/114.1
0.300 201.2/164.9
0.400 253.2/199.6
0.500 280.2/217.7
0.600 277/222
0.700 276/225

Holley
System
Max
Valve Size
Chamber Size
Intake Runner
Exhaust Runner
0.100
0.200 130/92
0.300 184/122
0.400 222/148
0.500 242/172
0.600 252/187
0.700

Brodix
IK180

Valve Size 2.02/1.60
Chamber Size 64cc or 70cc
Intake Runner 180cc
Exhaust Runner ?
0.100
0.200 138/112
0.300 188/149
0.400 234/175
0.500 243/175
0.600 245/178
0.700 276/225


How would these heads run with the following cam and why? What I am trying to do is understand how they relate to each other.

Comp Cam
Duration @ 0.006: 274/286
Duration @ 0.050”: 230/236
Max Lift w/ 1.5RR: .487”/.490”
Lobe ID’s: 5445/5208
Lobe Separation: 110
Intake Centerline: 106

Also what is the difference between 1.5 and 1.6 rockers?

http://www.j-performance.com/index.php? ... view&id=48
 
Re: what do head flow number mean?

OK LETS BREAK IT DOWN

heres your example

AFR the manufacturer
195 the cubic centimeter volume of the intake port in the heads
Eliminators name of the type of head
Valve Size 2.055/1.60 dia. of intake and exhaust valves
Chamber Size 65cc or 75cc optional combustion chamber sizes
Intake Runner 195 the cubic centimeter volume of the port in the heads
Exhaust Runner 80 the cubic centimeter volume of the port in the heads
ok below you see a chart the first number in each line is the distance the head of the valve is off the valve seat, when it was tested for flow ,the second number is air flow at the intake port with the valve at that height, the third number is the exhaust flow at the same height, exhaust valves are smaller so they flow less on a flow bench, all valves/ports are generally tested on a flow bench at a vacume equal to 28" of water vacume
0.100 70.4/56.7
0.200 149.5/114.1
0.300 201.2/164.9
0.400 253.2/199.6
0.500 280.2/217.7
0.600 277/222
0.700 276/225
HEAD FLOW is measured on a FLOW bench at a standard of 28" of vacuum ,the higher the flow number the more air/fuel mix can in theory flow into the cylinders at that valve lift, but only if the valve is open that far,so both lift and duration will effect the flow thru the port as will the rpm level and exhaust scavenging , if you have a cam that only has a .523 lift ,flow rates above .523 are meaningless in any calculation because your port will never see those flow rates, keep in mind , even if the heads flow that rate the intake or exhaust may be restricting that potential flow significantly.
also keep in mind if the valve max lift is at lets say .600, its only open that far off the seat once per intake cycle while its at the lower lift flow rates twice, making those more important in the calculation.
and remember the cam lobe can be a good deal different and still have the same listed lift and duration.
FlatVsRollerChart.gif

viewtopic.php?f=52&t=3802
volumetric.gif


viewtopic.php?f=52&t=8460&p=29682&hilit=head+flow+numbers#p29682

low07_zoom.jpg

threads you need to read

http://racingfeed.com/downloads/chevy_flow_data.pdf

viewtopic.php?f=52&t=333

viewtopic.php?f=52&t=322

viewtopic.php?f=55&t=8485&p=29767&hilit=volumetric#p29767

viewtopic.php?f=55&t=624&p=28122&hilit=head+flow+numbers#p28122

viewtopic.php?f=52&t=462&p=24466&hilit=head+flow+numbers#p24466

viewtopic.php?f=38&t=1099&p=26215&hilit=head+flow+numbers#p26215

viewtopic.php?f=52&t=126

viewtopic.php?f=52&t=796

viewtopic.php?f=52&t=92

http://www.carcraft.com/techarticles/11 ... index.html

http://www.profilerperformance.com/sbc-heads-176.html

http://www.circletrack.com/enginetech/c ... index.html

theres a good deal of info on assembling a 383 -406 sbc in this thread you might need

viewtopic.php?f=69&t=261&st=0&sk=t&sd=a&start=10

http://users.erols.com/srweiss/tablehdc ... _Big_Block

up to the rpm range where the port cross sectional area becomes a restriction to flow a smaller port is usually superior
for torque produced, larger ports tend to be less responsive and produce slightly lower torque so you need to match the flow to the displacement and rpm range
 
http://www.carcraft.com/techarticles/cc ... index.html

Edelbrock Performer RPM-O "Roval"
2.19/1.88 valves
110cc chamber
Intake port volume: 290 cc
Stock location exhaust port
Intake cross-section: 3.07 sq. in.
PN 60479

Valve Intake Exhaust E/I
Lift (no pipe)
0.100 66 58 88%
0.200 135 126 93%
0.300 196 149 76%
0.400 240 171 71%
0.500 264 189 71%
0.600 281 203 72%


Dart 275 Oval Port
2.25/1.88 valves
119cc chamber
Intake port volume: 275 cc
Raised exhaust port: 0.300 inch
Intake cross-section: 3.26 sq. in.
PN 19000112

Valve Intake Exhaust E/I
Lift (no pipe)
0.100 68 68 100%
0.200 151 115 76%
0.300 215 155 72%
0.400 259 192 74%
0.500 293 223 76%
0.600 315 244 77%
0.700 310 259 83%

TFS Oval Port
2.300/1.88 valves
113cc chamber
Intake-port volume: 280 cc
Exhaust port raised 0.300 inch
Intake cross-section: 2.84 sq. in.
PN 41300002

Valve Intake Exhaust E/I
Lift (w/ pipe)
0.100 69 61 88%
0.200 141 126 89%
0.300 209 159 76%
0.400 260 192 75%
0.500 292 221 75%
0.600 318 246 77%
0.700 325 264 81%

Brodix Race-Rite Oval Port
2.25/1.88 valves
Chamber 118 cc (110 cc CNC as tested)
Intake-port volume: 270 cc
Stock exhaust-port location
Intake-port cross-section: 3.08 sq. in.
PN 2061001 (RR BB-O)

Valve Intake Exhaust E/I
Lift (w/ pipe)
0.100 74 64 86%
0.200 163 113 69%
0.300 218 145 66%
0.400 267 171 64%
0.500 306 194 63%
0.600 328 216 66%
0.700 341 234 68%
0.800 348 244 70%

GM 236 Iron Peanut Oval Port
2.06/1.72-inch valves
120cc chamber
Intake-port volume: 208 cc
Stock exhaust port location
Intake-port cross-section: 2.43 sq.in.

Valve Intake Exhaust E/I
Lift (w/pipe)
0.100 56 44 78%
0.200 125 90 72%
0.300 183 117 64%
0.400 215 139 64%
0.500 233 158 68%
0.600 235 166 71%
0.700 235 172 73%

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POWER CHART
Iron Stock Edelbrock Dart TFS Brodix
RPM TQ HP TQ HP TQ HP TQ HP TQ HP
3,200 595 363 610 372 605 368 612 373 619 377
3,300 594 373 609 383 604 379 612 384 614 386
3,400 594 385 611 396 606 392 614 398 615 398
3,500 595 396 613 408 608 405 617 411 618 412
3,600 595 407 613 420 610 418 619 424 621 426
3,700 593 418 615 433 612 431 622 438 623 439
3,800 592 428 616 457 614 444 624 452 624 452
3,900 591 439 618 459 615 457 626 465 625 464
4,000 590 449 618 471 615 468 626 477 626 477
4,100 589 460 617 482 614 479 625 488 626 488
4,200 587 470 615 492 611 489 622 498 623 498
4,300 585 479 612 501 609 498 619 507 620 507

4,400 581 487 609 510 606 508 616 516 616 516
4,500 577 495 607 520 604 518 614 526 613 525
4,600 572 501 605 530 603 528 613 537 611 535
4,700 565 506 602 539 602 539 610 546 609 545
4,800 558 510 598 547 600 548 607 555 606 554
4,900 551 514 593 553 597 557 604 563 602 561
5,000 543 516 587 559 593 564 599 571 598 569
5,100 534 518 582 565 588 571 595 578 593 570

5,200 525 519 576 570 583 577 590 584 588 582
5,300 515 520 570 575 578 583 583 589 583 588
5,400 507 521 563 579 572 588 576 593 576 593
5,500 496 519 555 581 566 593 568 595 569 596
5,600 487 519 546 582 558 595 558 595 560 597
5,700 476 517 536 582 549 595 547 594 550 596
5,800 465 513 527 582 538 595 537 593 538 595
5,900 451 507 518 582 528 594 527 592 528 593
6,000 438 500 510 582 519 593 517 590 517 591
6,100 423 492 500 581 506 588 505 586 507 589
6,200 407 481 487 575 494 583 490 579 495 584

Peaks and Averages
Avg. TQ Avg. HP Peak TQ Peak HP
Iron 541.1 475.0 595 521
Edelbrock 582.1 514.9 618 582
Dart 584.2 517.7 615 595
TFS 590.3 522.5 626 595
Brodix 590.8 523.0 626 597
 
grumpyvette said:
POWER CHART
Iron Stock Edelbrock Dart TFS Brodix
RPM TQ HP TQ HP TQ HP TQ HP TQ HP
3,200 595 363 610 372 605 368 612 373 619 377
3,300 594 373 609 383 604 379 612 384 614 386
3,400 594 385 611 396 606 392 614 398 615 398
3,500 595 396 613 408 608 405 617 411 618 412
3,600 595 407 613 420 610 418 619 424 621 426
3,700 593 418 615 433 612 431 622 438 623 439
3,800 592 428 616 457 614 444 624 452 624 452
3,900 591 439 618 459 615 457 626 465 625 464
4,000 590 449 618 471 615 468 626 477 626 477
4,100 589 460 617 482 614 479 625 488 626 488
4,200 587 470 615 492 611 489 622 498 623 498
4,300 585 479 612 501 609 498 619 507 620 507

4,400 581 487 609 510 606 508 616 516 616 516
4,500 577 495 607 520 604 518 614 526 613 525
4,600 572 501 605 530 603 528 613 537 611 535
4,700 565 506 602 539 602 539 610 546 609 545
4,800 558 510 598 547 600 548 607 555 606 554
4,900 551 514 593 553 597 557 604 563 602 561
5,000 543 516 587 559 593 564 599 571 598 569
5,100 534 518 582 565 588 571 595 578 593 570

5,200 525 519 576 570 583 577 590 584 588 582
5,300 515 520 570 575 578 583 583 589 583 588
5,400 507 521 563 579 572 588 576 593 576 593
5,500 496 519 555 581 566 593 568 595 569 596
5,600 487 519 546 582 558 595 558 595 560 597
5,700 476 517 536 582 549 595 547 594 550 596
5,800 465 513 527 582 538 595 537 593 538 595
5,900 451 507 518 582 528 594 527 592 528 593
6,000 438 500 510 582 519 593 517 590 517 591
6,100 423 492 500 581 506 588 505 586 507 589
6,200 407 481 487 575 494 583 490 579 495 584

Peaks and Averages
Avg. TQ Avg. HP Peak TQ Peak HP
Iron 541.1 475.0 595 521
Edelbrock 582.1 514.9 618 582
Dart 584.2 517.7 615 595
TFS 590.3 522.5 626 595
Brodix 590.8 523.0 626 597
Click to expand...

This might be a little easier to read, then those numbers above.
 

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