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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Originally Posted by Thierry25 View Post

... past the max TQ band , we can see the torque is dropping dramatically. This drop tell us directly that barrel filling becomes very poor. ( due to the cams, turbo, intake and exhaust limit...). Somewhere step by step, air can not go in and exhaust gas can not go out.

So past the max TQ band, the flow is mathematically increased by RPM but is decrease by filling efficiency. So I think the air flow doesn't increase so much .

Then be back to the so called Kjet behaviour (stock), I think the max fuel capacity of the Kjet is already achieved at little above max TQ band. Past this point the air flow increase slowly but as the flowed fuel is already at it max, the AFR is increasing step by step either.

Then when we switch to more agressive cams, we never get any problem with mid RPM ( since the kjet is self tuning ) but past it fuel capacity we hit the limit in sharper way. No matter higher or a bit lower RPM is ....

Dropping the pressure control doesn't change anything... the metering plate is fully moved ( or very nearly).

Acting the lambda freq valve doesn't change anything either...For max capacity it is even much better to turn it off and to increase the valves adjs. screws. ( Remember this FV returns an important amount of fuel to the tank)

Increase the fuel system pressure ( by shimming the head) bring almost nothing it self.
Thanks for the correction on the CP for the 3.3 & 3.6 heads.

I like your thoughts on where gross air flow is.

Peak TQ is where the motor is running at its most efficient level.

Peak HP is where it is probably using its max air and fuel.

The metering plate moves quickly at first with changes in air flow. Partially to the ratio of the arm to the metering pin but mostly due to the shape of the metering cone.

As we get to higher air flows, the metering plate dose start to slow as air starts finding a more direct path off the end of the metering plate and the plate extends past the metering assembly exit. I say it stalls but to say it slows is probably more accurate.

There is about one full point of added fuel available by reducing CP below stock. This has been the corner stock of the Andial WUR sense the beginning. I believe after about 1.9 bar there is nothing to be gained.

So, after we hit peak HP and air flows fall off, do we want the fuel level to fall off to or do we want to maintain our goal AFR.

If we can get the metering function to compensate for changes in air flow accurately at our expanded air flows it will be self compensating.

Maybe the key is lower restriction injectors and a larger metering cone to a degree.

At some point increasing the flow of the FD is needed but we need to do so in relation to changes in air flow.
Old 01-06-2010, 05:26 PM
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