How much CSA will be ideal

[digger]

I have never seen a big port hurt torque and hp.
But this is on 4 cylinder engines where I can adjust the runner length for bet hp and totque.
I think that you are wave tuning the engine with port velocity on a single 4 barrel V8 engine.
A smaller CSA makes the wave travel back and forth slower so the engine tunes as if the port was longer.
With a bigger port it takes less time for the wave to arrive back to the valve so the engine can tune at to high rpm.
Intake valve open waves.

Erland

also on the engines you deal with you probably cant get aftermarket castings that are a lot bigger? youre probably restricted to what material is in there to begin with so you physically cant remove enough material to see the effect to any great degree

[Stan Weiss]

I also use VE as part of my calculation.

Stan

ab-csa-371.gif

[swampbuggy]

Stan thanks very much for posting your chart there it confirms what I expected I needed about 3.2 3.3 mark

[Rick360]

Stan thanks very much for posting your chart there it confirms what I expected I needed about 3.2 3.3 mark

Just go ahead and make it 3.5 and you'll get 125% VE. Or make it 3.8sqin and it'll be good for 140%VE.

If it only worked like that.

Rick

[pcnsd]

Stan thanks very much for posting your chart there it confirms what I expected I needed about 3.2 3.3 mark

Just go ahead and make it 3.5 and you'll get 125% VE. Or make it 3.8sqin and it'll be good for 140%VE.

If it only worked like that.

Rick

I believe it was Jim McFarland that suggested you can add a bit of CSA on the intake to extend the useable RPM range (overrev) at the cost of some peak HP. I hear it is something dirt racers find useful.

[Stan Weiss]

Stan thanks very much for posting your chart there it confirms what I expected I needed about 3.2 3.3 mark

Just go ahead and make it 3.5 and you'll get 125% VE. Or make it 3.8sqin and it'll be good for 140%VE.

If it only worked like that.

Rick

L M A O

That is some funny stuff. Useless but still funny.

Stan

[GARY C]

Stan thanks very much for posting your chart there it confirms what I expected I needed about 3.2 3.3 mark

Just go ahead and make it 3.5 and you'll get 125% VE. Or make it 3.8sqin and it'll be good for 140%VE.

If it only worked like that.

Rick

What does your data show?

[Rick360]

How do you even go about using that chart? Do you already know what ve the engine will have? or do you pick the ve you want and size it for that?

Rick

[GARY C]

How do you even go about using that chart? Do you already know what ve the engine will have? or do you pick the ve you want and size it for that?

Rick

If your asking me, I am chart retarded, I just see colored lines I am just curious what you guys have found. I am not sure what to make of VE, I have a dyno sheet for a 357 making 530 horse but only 400 ft lbs but producing 117% VE until the nitrous is tuned on and then it drops to 100% VE. and produce over 700 hp.

[user-23911]

If you take a high powered OEM engine that's tuned on SD, take a look at the tables in the ECU you might find that the VE is mapped at up to 140%.
If you choose the right engine to look at?

A smaller CSA makes the wave travel back and forth slower so the engine tunes as if the port was longer.
With a bigger port it takes less time for the wave to arrive back to the valve so the engine can tune at to high rpm.
Intake valve open waves.

Erland

Changing the CSA changes the amplitude of the wave, not the speed of the wave.
In changing the amplitude you also change the frictional losses so the wave will also change it's decay time.

[user-23911]

Changing the CSA also changes the average gas flow rate. That will speed up the overall wave speed in one direction while slowing it down in the other direction.

[swampbuggy]

Rick, Stan's data on the CSA chart/graph i can assure you was not pulled out of thin air. I am sure that the data within the chart/graph was figured out (established) over the years thru trial and error (R&D) with engine combos. The VE calculation, the same way, it is based on Bore and stroke and proven combos (some of the engine pieces not mentioned but assumed to ideal like carb, intake, camshaft, exhaust system). I am not saying charts/graphs are 100% accurate BUT they for the most part pretty darn close, AGAIN....established on (been there-done that).

[digger]

So if I have 220fps and csa 4 I'll make same power as a head with 350fps and 2.5csa ?

[Frankshaft]

An honest question. Stan, do you race, have cars, or build engines, that you race or port heads? Just curious. This is NOT a dig either, so don't take it that way. Just a question.

[Warp Speed]

Stan, you have 2.02/1.60 valve size listed in your chart?