Came across this info while doing some research and thought I'd share.
http://www.hobracing.com/tech/tpi_flow.asp
TPI Intakes and runners
The following airflow tests were performed on the University of Northwestern Ohio's SuperFlow SF600 Flow Bench. All CFM values are corrected for airflow at 28 inches of water. Injector flow rates are flowed at 43.5 PSI on an injector flow bench using test fluid with same density as gasoline.
AirFlow
Stock TPI/LT1 48mm Throttle Body w/o airfoil -- 783.0 cfm
Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm
TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm
TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm
Stock 98 Camaro 3800 II Throttle Body -- 554.3 cfm
Stock TPI Bosch MAF sensor w/ screens -- 517.8 cfm
Stock TPI Bosch MAF sensor w/o screens -- 658.4 cfm
Stock 87 GN 3.8L Turbo AC MAF sensor w/ screen -- 584.2 cfm
Stock 86 2.8L AC 5-wire MAF sensor w/ screen -- 576.2 cfm
Stock 96-up AC 3100 V6 MAF sensor w/ screen -- 616.4 cfm
Stock 96-up AC 3100 V6 MAF sensor w/o screen -- 670.7 cfm
Stock 94-up LT1 MAF Sensor w/o screen -- 719.0 cfm
Stock 85-87 Firebird TPI airbox mid piece -- 499.3 cfm
Stock 4.3/5.0/5.7 2bbl TBI complete -- 574.1 cfm (dry)
Stock 4.3/5.0/5.7 2bbl TBI w/o injectors -- 584.7 cfm
Stock 3800 vin L throttle body w/ screen -- 419.1 cfm
Stock 3800 vin L throttle body w/o screen -- 444.8 cfm
4bbl MPFI Holley Throttle Body -- 1287.6 cfm
Another source sent in these flow numbers
Flow and HP ratings for Throttle-bodies:
Flow (cfm) Max. NA HP
Stock 668 300
Stock w/airfoil 710 350
52MM w/airfoil 835 400
54MM (AS&M) 900 450
58MM 1050 500
TPI Intakes and runners flow rates
Stock intake manifold with runner
Stock....................198.72 cfm
ACCEL................213.52 cfm
Extrude/ACCEL....217.11 cfm
Super Ram............220.67 cfm
the stock TPI has a hard time flowing 230cfm even with minor port work, look here
most of this info is right off the accel,holley,edelbrock, and TPIS sites, add a little math and the results become much clearer!!!
Intake....... length ....... port in -- out
Stock GM Base--- 6.375"------ 1.47"- 1.96x1.2
TPiS base------ -6.125"------ 1.75"- 2.09x1.28
Accel base----- -6.125"------ 1.75"- 2.09x1.28
Holley base------- 6” runner 2.3”- 1.9”x 1.23 (2.337 sq inches)
Runners
Stock TPI----- -- 7.250"------1.470" round(1.70 sq inchs)
SLP ----------- - 6.625"------1.600" round (2.01 sq inchs)
Accel LTR------- 6.625"------1.615" round (2.05 sq inchs)
TPiS----------- 7.625"------1.660" round (2.168 sq inchs)
Mini ram -----3.5”
LT1 ----------3”
Runners (measured individually)
Stock....................203.17 cfm
ACCEL................242.02 cfm
Extrude/ACCEL...275.83 cfm
Super Ram............289.18 cfm
Intake manifold with 3/8 inch radiused intlet.............................222.45 cfm
Holley stealth ram ………..275cfm
Stock intake manifold with runner
Stock....................198.72 cfm
ACCEL................213.52 cfm
Extrude/ACCEL....217.11 cfm
Super Ram............220.67 cfm
Holley stealth ram …..275cfm
ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet.........251.51 cfm
ACCEL Hi-Flow intake manifold with runner
Stock....................215.83 cfm
ACCEL................232.53 cfm
Extrude/ACCEL....243.21 cfm
Super Ram............240.24 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet ...............275.83 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with ACCEL runner ..............266.94 cfm
Edelbrock Performer RPM manifold (Stock)..........286.51 cfm
Edelbrock Victor Jr. ............275.24 cfm
HOLLEY STEALTH RAM
the HOLLEY STEALTH RAM FLOWS at 275cfm out of the box, and has the potential when matched to the correct heads and cam to totally out flow most other intakes available,can easily reach 300cfm with minor port work and costs much less
Stock…………………………… 275cfm
Ported…………………………..300cfm
Runner lengths
Stock tpi manifold 8” runners 11.25”, cylinder head 6” total 25.25”
Accel super ram manifold 8” runners 7” cylinder head 6” total 21”
Holley stealth ram manifold 6.26” ” cylinder head 6” total 12.26”
Edelbrock performer RPM runners 6” ” cylinder head 6” total 12”
Edelbrock vic jr , runner length 5.5” ” ” cylinder head 6” total 11.5”
while several guys brought up valid points to check, Ive found that the one most commonly over looked in my experience is that the stock exhaust system, is highly restrictive, and the stock fuel delivery system is not adequate,for the potential power, the heads and intake, allowable air flow potential, are all restrictive, and the stock cam timing and lift is already near max as it was designed to produce about 260 hp,and operate at under 5700 rpm, if you try too add an additional 100-200 hp, and 1000rpm-2000rpm to the engines power band, and too the engines output youll quickly find this to be a factor.
heres a bit of advice! so many times I get called over to help in some project, only to find the problems the guys hoping I can solve could have been avoided entirely ,
if the guy whos at this point is going partially insane, had only bothered to carefully read the details or installation instructions.
many times youll see the guy ordered the wrong part number, and theres a very similar component that exactly matches the concept ,
hes currently waist deep into, only to find the component he ordered is not compatible with the rest of the parts, hes working with.
Ive seen guys order high impedance injectors that are installed on a controller designed for low impedance injectors
http://fuelinjectorclinic.com/faqs
You can
measure the resistance across the two electrical terminals of the
injector. If the resistance is between 1.5 and 4.0 Ohm you have low
impedance injectors. If the resistance is between 8 and 16 Ohm you have high
impedance injectors.
https://www.hotrod.com/articles/hrdp-1211-low-impedance-vs-high-impedance-fuel-injectors/
Low impedance (peak and hold)
injectors have a resistance of
between 2 and 4 ohms.
High impedance(saturated)
injectors have a resistance of
between 10 and 14 ohms.
Low impedance and
high impedance injectors cannot be used interchangeably without modification of the
injector drivers.
What are the differences between low impedance/peak & hold and high impedance/saturated injectors?
The older fat body style low impedance injectors (1.5 to 4.0 Ohm) used to have faster open and close times due to the type of electrical signal pattern emitted by an ECU equipped with proper P&H signal transmitters. This “Peak and Hold” injector signal typically uses a high (4 amp) initial current to open the injector, and which reduces to a lower (1 amp) current to keep the injector open until the pulse ends. Since this method put less total current into the coil, the coil heated up less and was therefore more reliable. Since the “hold” or lower current part of the signal has created a weaker magnetic field, the injector will also close more quickly.
High impedance injectors (10 to 16 Ohm) are triggered by a low (typically around 1.2 amps) constant current signal and kept open by the same constant (saturated) current for the entire cycle. Most OEM injectors today are high impedance injectors being driven by saturated injector signals from the ECU since car manufacturers are most interested in the simpler saturated signal which is more cost effective to produce when building ECU’s, especially where there is no apparent loss of drivability or performance.
https://www.summitracing.com/parts/...MIsMryyOf_3gIVjoTICh1o7wzhEAQYAiABEgKO9fD_BwE
https://www.summitracing.com/parts/...MInIGXief_3gIVy-DICh1rpgH3EAYYAiABEgJLafD_BwE
