Ugrading The Plenum For A N/a

[useless]

Hey Greg ..how ya going?

I catch your drift mate. That plenum looked like the xr6t plenums.Even though I have alot of respect for all things living I dont like the look of the log plenums. Not trying to disrespect the great warrior workshops here but I think the log plenums as a whole look like a big milk bottle!! Some mechanic woke up one day with his head full of design questions and when he saw the bottle of milk he created the log plenum.

Regardless of what the experts say the crappy position of the the throttle body would give uneven distribution to the cylinders turboed or not. I would take an educated guess that spark plug number one one all of these so equiped cars would show a leaner mixture than the other 5 cylinders.This is likely why Daniel probably lunched his engine and lost power after tuning.

In any case I am not here to teach workshops what they should be doing. I am a car phone installer!!

I am talking about improving what we already have..making it better.

[Adam]

So one N/A engine blows and you blame in on a plenum which is used successfully on hundreds of other cars making far more power!

[useless]

So one N/A engine blows and you blame in on a plenum which is used successfully on hundreds of other cars making far more power!

It is my opinion only Adam. Are their number one plugs running leaner ? When distribution discrepancies are fixed then cars can make more power regarless of their current level.

Also when one cylinder varies and the car is tuned at certain a/fuel ratios then it is very prone to pinging ,detonation and engine failure. Thuis is why the gung ho tuners tune alot of cars at richer settings.Because they are scared.

Edited 08/03/08 03:33 AM by useless

[Adam]

Can you please explain how the number one cylinder runs leaner than the rest?

[senna_T]

I'm with adam on this one, the valve will only open so much, and the bigger plenum will obviously be supplying more air than the standard one, so whats the difference?

[useless]

Can you please explain how the number one cylinder runs leaner than the rest?

6 cylinders right? Each causes its own vacuum in the manifold correct? Where do you think in the plenum will be the strongest vaccum pulse?Where will be the strongest negative pressure? At wot for example? Will it be at the half of the plenum closer to the throttle body or the farthest away? Remember that vaccum should drop to 0 inches of mercury at wot right? Now your turn champ..

[senna_T]

but if the plenum is shaped correctly and tapered, shouldn't it be creating higher pressure areas towards the back where the plenum chamber gets smaller?

[Adam]

So, are you trying to say that the cylinder furtherest from the throttle body is starved for air?

If so that's number 6 not 1.

I'm no expert and I'm not going to pretend to be one but if a throttle body at one end of a plenum can work for Ferrari, Porsche, Holden, Nissan, Aston Martin etc etc with up to twice as many cylinders I think it can work on a Falcon.

[useless]

but if the plenum is shaped correctly and tapered, shouldn't it be creating higher pressure areas towards the back where the plenum chamber gets smaller?

Think of it this way.As each cylinder causes a vacuum which cotributes to total manifold vacuum then putting the throttle body on one end would negate as air moves towards the back intake ports as it is travelling from the front of the manifold to the back .

When the throttle is cracked open then the full manifold pressure draws the larger volume of air to the first port.The first port draws on the large volume of air coming in.The second port then takes in the leftover of port one and velocity is reduced as opposed to port one because port is not contributing to the total vacuum available at port 2.Once port 2 finishes then the air will arive at port 3 .At port 3 you no longer have the added vacuum of port 1 and 2 and so total vacuum at that part of the maifold will be less than when it has reached 1 and 2. The air will then travel to port 4 which will have a total available volume less than port 4 as the total volume will only be dictated by the vacuum of the last ports. What this phenomena means is that the last cylinder will be richer and the first will be leaner.

[Adam]

Not all cylinders draw air at the same time.

You're making it sound like it's sealed and the only air available is what's in the plenum. Air is replaced as it's drawn in.

The cylinder itself creates the vacuum so the air will be drawn into it regardless of it's position.