Cylinder head flow - What is crucial in a stocker?

[Stan Weiss]

You can also look at what some call "Piston Flow Demand". This is calculated by using engine RPM (Time) and change in Volume above the piston. This graph is a 305 ci @ 7000 RPM

Stan

[jamie2370]

What I can tell you is this. You can take a sbc stocker combo, put decent shortblock in it, do only the allowed valve job to the heads with best valves and springs, assemble with the latest greatest cam and lifters, put it in the car with a name brand carb, name brand trans and converter and I can almost guarantee you won't be within 7 tenths of the top cars with that combo. SO....heads and intake are 90% of the power. Plus if they really answered your question then they couldn't charge $5000 for a set of stocker heads and $1800 for an intake lol

[HP HUNTER]

Originally Posted by Chipper Chapman

I realize that most stock eliminator engines don’t have what we would call “high” amounts of valve lift. But my question is, considering the amount of dwell at maximum lifts due to our day long durations, where is improving the flow and velocity more crucial? Is it low lift, .100-.300 or what we’ll call higher lift of .350 and up? Typical engines we would not consider maximum max lift flow numbers for much more than bragging rights, and would consider the low and mid lift to be more important as the valve passes through that area twice, which yes it still does, albeit extremely fast. Obviously improving it everywhere is the best case, but often what improves low lift can hurt the high lift and vice versa. So what is the more critical area of improvement in these situations?

I will answer your question: My stocker combination also had .398 lift @ the valve. I dyno tested my engine as it came out of the car 474 HP @ 5400 RPM. I re rung the short block and turned my attention to the heads and intake. I focused on the .200 .300 .400 lift flow and made a nice gain. The engine went back on the dyno, I now had had 513 HP @ 5700-6000. In the real world that HP increase picked my car up exactly 3.2 MPH.
A BBC oval port head with either .398 or .460 lift @ the valve will require either welding the intake seat or Intake valve seats to do what your trying to do, as cast the bowl is too big for a 2.070 valve, which destroys low lift flow.



Example

[Mark Yacavone]

Originally Posted by HP HUNTER

I will answer your question: My stocker combination also had .398 lift @ the valve. I dyno tested my engine as it came out of the car 474 HP @ 5400 RPM. I re rung the short block and turned my attention to the heads and intake. I focused on the .200 .300 .400 lift flow and made a nice gain. The engine went back on the dyno, I now had had 513 HP @ 5700-6000. In the real world that HP increase picked my car up exactly 3.2 MPH.
A BBC oval port head with either .398 or .460 lift @ the valve will require either welding the intake seat or Intake valve seats to do what your trying to do, as cast the bowl is too big for a 2.070 valve, which destroys low lift flow.



Example

There ya' go..Talk about sharing..Wow!

[Billy Nees]

Originally Posted by Mark Yacavone

There ya' go..Talk about sharing..Wow!

Hey Yac, what do you think it's gonna take to make THAT^^^ look "stock"?

[Larry Hill]

Looks like a good start for Super Stock.

[HP HUNTER]

Originally Posted by Larry Hill

Looks like a good start for Super Stock.

Well then you can say the welding is for Super Stock and the seats are for Stock.........theres more than one way to get there.

[Glenn Briglio]

Originally Posted by Billy Nees

Hey Yac, what do you think it's gonna take to make THAT^^^ look "stock"?

Special medicine..........

[Adger Smith]

Correct Velocity, Velocity, Velocity
Flow is always talked about & highly sought after, but
the correct Velocity is what accelerates the engine/vehicle and is seldom mentioned.
Just my .02 for free.