vetteboy86

What should the air flow be for a 350 and a 383? I assume that the 383 should be more correct? If anyone has some numbers I would greatly apprecieate it. The motor I have is a mild 383.

doc

What are you specifically talking about? At idle, at 6,000RPM WOT???

I would think that the airflow would be in a ratio of the cubic inches, in other words, the 383 should flow 9.4% more air at each measured RPM.

vetteboy86

Sorry I didn't specify which RPM range I was refering too. However your answer somewhat confirms my thinking. I believe the air flow into my engine or that measured by the maf is somewhat low. What would a stock 350 TPI flow across the RPM range?

doc

If you can look at the MAF tables for a MAF car, then you will find six tables showing flow in gms/sec vs voltage, but not vs RPM. Some one would have to run a scanner to data log air flow VS engine RPM. My scanner will not data log, I only get a snap shoot in time.

vetteboy86

The software I am using to log the car shows me air flow in grams/sec and I believe it to be low. At 5500 RPM's the maf is only reading 207 grams/sec. However in the tables in tuner pro I see a maximum of 255 grams/sec. So I figure that the car is running terrible up top because the air flow isn't where it is supposed to be. If i knew for sure, I would change the tables, but my gut is telling me that the maf just isn't right. I have descreened it since this last scan, but I still wonder.

grumpyvette

are you asking what CFM your engines THROTTLE BODY or CARB requires?

or are you asking how many cfm at a certain valve lift a cylinder head port must flow to reach a set hp number?

perhaps the fuel injecters flow rate?

could you get into ALOT more detail about what your trying to find out???

http://www.rbracing-rsr.com/runnertorquecalc.html

http://www.chevyhiperformance.com/te...ench_database/

http://www.rbracing-rsr.com/fuelinjectors.htm

http://www.bgsoflex.com/intakeln.html

http://www.engr.colostate.edu/~allan...a/effarea.html

http://users.erols.com/srweiss/calchpaf.htm

http://users.erols.com/srweiss/calcpchg.htm

Index = (.300 * 4) + (.400 * 2) + (.500 / 7)
Flow Index = (flow @ * 4) + (flow@ * 2) +( flow@ / 7)
Potential HP based on Airflow (Hot Rod, Jun '99, p74):
Airflow at 28" of water x 0.257 x number of cylinders = potential HP
or required airflow based on HP:
HP / 0.257 / cylinders = required airflow (see below)

"Flow Index" refers to a formula Jody helped devise to compare driveability between the different cylinder heads. The formula is:
(cfm at .300 lift x 4) + (cfm at .400 lift x 2) + cfm at .500 lift


p88) Determining peak HP rpm based on peak head flow numbers. These numbers are based on flow measured at a 28" depression.
The formula is: (flow in cfm / 1.68 * 2000) / (Displacement ci / number of cylinders) = rpm.
(flow in cfm / 1.68 * 2000) / (350 ci / 8 cylinders) = rpm
(flow in cfm / 1.68 * 2000) / (43.75) = rpm


HP (engine)
Airflow (per intake port)

300hp
146 cfm

350 hp
170 cfm

400 hp
195 cfm

450 hp
219 cfm

vetteboy86

Lots of info there, that I am sure is useful. However now I am trying to figure out if I am outflowing the MAF sensor. My readings are low, which makes me think that it has reached its max and isn't functioning correct. Or perhaps something else is wrong.

Thanks