Box type upper intake manifold help

Originally Posted by 87stang

Port Velocity has to do with air being pulled through the intake by the piston as it moves in the cylinder and creates a vacuum. Air being pulled through a smaller port (into the same sized cylinder) will gain more velocity (speed) as it travels to the cylinder than a larger/shorter port will. What matters, in the case of low-rpm velocity, is what happens as the intake valve closes. Each time the intake closes, there is a rebound effect in the air flow. A longer port will "cushion" this rebound more at the lower rpm levels...resulting in better airflow into the cylinder, and thus more power.

Here's more science into it: Head Porting Principals

You are talking about 2 different things here...
1. Port Velocity
2. Ram Tuning
When you say that we need 'High Velocity' intake ports in order to make power at low speed, you are implying that velocities will only get higher as rpm increases.
This is bad if you want to rev your motor, as airflow will choke off.

Ram Tuning is a completely different set of rules.
The Pulse Wave can be manipulated by the camshaft, and there are secondary and tertiary Pulse Waves which can be used for Ram Tuning as well.
This is a big reason why (as Joel is saying) all the "Intake Comparison Testing" is actually invalid and completely irrelevant to anyone running even slightly different parts.
For example,
Using a cam designed for ram tuning at 2k rpm in a motor built (heads/intake) with the intent to ram tune at 6k would be silly... I would venture a guess that efficiency would be lost at both 2k and 6k rpm.
Still, many magazines try to make this comparison on a monthly basis.

Using the example of an intake valve...
The cam is what determines when the valve closes.
Therefore the cam controls the Ram Tuning.
That leaves the cam in greatest control of the rpm powerband.

Glad this has stayed civil,
jason

If the cam has the greatest control of the powerband, the intake would be a close 2nd.

I do believe that it's all about the combination of parts, and the examples I was able to find obviously are not optimized for every example, but they are valid examples of how intake design effects the powerband.

I will still argue that a box upper will give up low-rpm power to a long runner intake...in every application. Every application I've personally seen, has turned out this way...a trade-off in most cases. In some applications this is desireable: a softer torque hit, for more pull at the top of the tach.

Originally Posted by 87stang

If the cam has the greatest control of the powerband, the intake would be a close 2nd.

I do believe that it's all about the combination of parts, and the examples I was able to find obviously are not optimized for every example, but they are valid examples of how intake design effects the powerband....

... in those specific combination examples...

Originally Posted by 87stang

If the cam has the greatest control of the powerband, the intake would be a close 2nd.

I do believe that it's all about the combination of parts, and the examples I was able to find obviously are not optimized for every example, but they are valid examples of how intake design effects the powerband.

Don't leave the heads out of the picture. Box or short runner intakes do have their peculiarities, the problem with all the evaluations out there, is the "conclusive" statements they reach with settings favoring a type of setup over the other and the inhered association made by the readers...... for example....

Originally Posted by 87stang

I will still argue that a box upper will give up low-rpm power to a long runner intake...in every application. Every application I've personally seen, has turned out this way...a trade-off in most cases. In some applications this is desireable: a softer torque hit, for more pull at the top of the tach.

Again, I'm not contradicting your statement above, the only item missing, as vristang mentioned, is the "in those specific combination examples" discriminatory clause..... why?..... like you said, when you look into the combination of all the parts, and work on matching them, the results will not be the same.....

The simple fact is: a box intake is designed to improve performance at the top of the tach and not down low...regardless of the combination.

Originally Posted by 87stang

The simple fact is: a box intake is designed to improve performance at the top of the tach and not down low...regardless of the combination.

If that is the way you see it, there's no point in trying to explain.....like I said, I've worked 302 setups (N/A and SC) that have benefited from the box style intakes. Don't have dyno numbers, but an improvement in 1320' ETs with higher 60' numbers due to traction problems, is usually a good indication torque loss is null.

To the OP...

Originally Posted by StrokedGen1

Has anybody tried using a box type upper intake manifold running n/a or have any info I can read? 383 w/ GT40 Mass Air

You have a 383 stroker setup, match a box intake to the correct camshaft (custom would be the best overall choice), tune that EFI, set that AEFUEL function at optimum (Acceleration Enrichment); and you'll have plenty of torque "down low", better engine acceleration and average TQ/HP under the curve.