Edelbrock heads Vs. Stock 291-c's the unequivocal truth

[jeepsr4ever]

Did I read these numbers right? sothe Eddies outflow the indy street heads?

These are the flow numbers I got on my Indy heads after I reworked them...hoping I didn't lower the flow. I think I did alright just by going by feel and eye.... (bottom row is the flow )

My cam's max lift is .560 anyway. And the cam was made going by the catalogs flow numbers...maybe next time I will use a roller with these numbers.





Out of the catalog...

[Holeshot]

note that the home porting wizard's test pressure on the previous post's pic is only 8", while Indy used 28"!!!!!

Makes a HUGE difference!!!

[jeepsr4ever]

Ah yes

[401 Pacer]

Please permit me to further confuse and astound y'all....

Flow numbers don't mean sh1t

What I mean is that they don't tell the whole story. Some critical, but almost always overlooked, considerations include the BALANCE of flow BETWEEN the intake AND exhaust port. Too much on one or the other and you hit a wall.

This can be compensated somewhat with exhaust tweaks (more or less restriction) but only so far.

Anudder thing is turbulence....when and where. I know some porters (not the kind who clean the crapper at the bus station) who listen to the air flow while they work their magic. Think: snazzy stethoscope.

I reiterate, numbers don't mean sh1t UNLESS you know how to apply them effectively. Remember "Advertised Duration"? Case closed!

[Holeshot]

Flow numbers DO mean a LOT!!!!

That's one set of data we have to compare one head to another.

Flow numbers give us at least some data to compare.

As far as intake -vs- exhaust, that is yet another variable that is open to interperetation, and can vary with type of induction & exhaust used.

Perhaps nearly as important as overall flow numbers, is having each port flow the same as the rest do. The home port job without a flow bench may yield ports that vary 10~30% between like ports, meaning you may have one port flowing 300CFM and another flowing 270CFM. Try to get correct mixture distribution with that!!! Not gonna happen, never will run to full potential.

So having a set of flowed heads (& intake) is EXTREMELY important to extracting max performance by allowing equal mixture distribution and tuning to the edge without getting a lean & detonating cylinder.

Speaking of balancing the flow, a stockcar wrench I knew would use pingpong balls to shove into the primary header pipes to check for equal length - each pipe should hold the same number of balls.

Also, rust inside of the primaries can reduce diameter and flow enough to be measured on the dyno.

[401 Pacer]

Ya ain't gettin mah meanin!

Flow numbers, like most data, can and IS manipulated to the point that it's almost useless more often than not....and when the tests are done under different parameters (such as level of suction etc) then it's worse than apples and oranges.

What I be tryin to say is: THINK! Don't blindly go by numbers. Ask people who you respect (or have solid reputations) what their REAL WORLD RESULTS are.

Guess I've been watching too many commercials "New and improved!"

Not bustin your chops, I just want people to be critical thinkers.

[jeepsr4ever]

Most times you flow the heads and then get a cam grind to get that 82% efficiency variable between intake and exhaust....just to put it to bed