What's the max displacement stock L-jet can handle? Options

[newto914s]

I know that because of the Air mass sensor on the L-jet it can handle some slight increases of displacement without too much trouble. Engine sucks in a little more air and it compensates with-in reason.
So I'm wondering where the line is if you just increase the bore size where the L-jet will not be able richen the mixture enough. 96mm, 100mm, 103. I've heard some guys use the 1.8 L-jet on the 2.0, so a 10% increase. So if your starting with a 2.0 bus L-jet system it should be able to handle 2.2 liters, right?

[ClayPerrine]

The L-Jet system can handle as much displacement as you want to put on it. But you have to recalibrate the AFM to handle the difference in displacement, and that is very tricky. This works until the AFM becomes a restriction in the intake run that can hurt performance. And the AFM can only handle a small bump in camshafts before it flutters too much at idle. But the L-Jet system is real good for turbo motors.

[cantley914]

But the L-Jet system is real good for turbo motors.

Wasn't it said you can't turbo a 914 ??? (IMG:style_emoticons/default/confused24.gif) (IMG:style_emoticons/default/happy11.gif)

Steph

[newto914s]

I'm wondering what that limit is before recalibration is necessary.

[MrKona]

How does one recalibrate the AFM? What does this entail?

- Bryan

[Bleyseng]

Reset the AFM by moving the arm.
You must use a O2 sensor to determine the Air fuel Ratio as you move the arm.
I use a LM1 meter

[Brando]

After re-calibrating the AFS you can then change your injectors and/or fuel pressure to give the right amount of fuel.

[ClayPerrine]

The only other thing you will need to change for BIG displacement increases is the tension on the AFM spring. If it pegs the AFM due to airflow, increase the tension and reset the wiper contact.'

Without a calibration bench, this is going to be trial and error.

[Bleyseng]

Yes, you will have to adjust the spring tension on any big changes in airflow/CR as the vane will just peg.

If you can't get enough fuel using the 1.8/2.0 Ljet injectors you would have to find some off another brand of car. See the Bosch injector charts.

Change the fuel pressure? Hmm, its already a variable fuel pressure regulator as that vacuum line going the plenum adjusts the fuel pressure as the engines manifold vacuum changes.

0hg is wide open throttle so is full pressure bout 39psi
15hg is idle so normal pressure at 29psi

My guess is you could do a 2270 motor without a big cam and make it work with some tuning.
You would have to use the 914 runners and a bus plenum as the other stuff is just to little.

[914nerd]

But the L-Jet system is real good for turbo motors.

Do explain.
How does one go about setting up the L-Jet for a turbo motor?

(Yes, I know you can't turbo a 914, but that doesn't mean you can't try, right)
(IMG:style_emoticons/default/biggrin.gif)

[Brando]

Turbo application...

Twin turbos, one AFS on each side intake to turbo, two brains, 8 injectors maybe?

[Aaron Cox]

you make things waaay too complicated....

[tdgray]

you make things waaay too complicated....

(IMG:style_emoticons/default/agree.gif) There are much easier ways to go about this. Megasquirt for example. Sure tuning is a bitch but once you have it you have it (or so I am told... hey I teach therefore I cannot do (IMG:style_emoticons/default/smile.gif))

[newto914s]

Reset the AFM by moving the arm.
You must use a O2 sensor to determine the Air fuel Ratio as you move the arm.
I use a LM1 meter

So this is to adjust the idle mixture, and the air flow vane will handle everything else. So as long as it's not pulling so much air it pegs open. It sould be work able. I'd love go megasquirt but this is for my bus. Just looking for a little more punch and don't need it to rev.
I'm thinking if I just went to 96mm bore(from 94). I'd probably not need to touch anything. Everything over 96mm you have to machine the case, right?

[bd1308]

anything over 96's and you get cooling issues

[ClayPerrine]

But the L-Jet system is real good for turbo motors.

Do explain.
How does one go about setting up the L-Jet for a turbo motor?

(Yes, I know you can't turbo a 914, but that doesn't mean you can't try, right)
(IMG:style_emoticons/default/biggrin.gif)

Turbo goes between the AFM and the throttle body. the extra boost is handled by the AFM, just readjust the spring tension to keep it from pegging out under full boost, and adjust the wiper for the mixture.

If you need more fuel pressure, swap the regulator for a D-jet adjustable regulator.

[Bleyseng]

Clay, Djet had a non-adjustable regulator, Ljet comes with one.

96's are pretty thin for a bus and can cause heat issues.

You want more hp/torque in a bus? I rebuilt my 2.0L using Jake's 9550 cam and increased the valve sizes to 42x36. Now its a fun Westy to drive. Keep the CR ratio to 7.5 to 1 again for cooler running.
I have somewhere around 90hp now up from the stock 70.


Gawd, you guys have me thinking of turboing the WEsty now..hmmm,, fits inbetween the AFM and throttle body...fab up a exhaust.....stick in the turbo and tune it! Yeah Baby, 140hp!! Woo Hoo, I can really pass Mini Winnies with that combo!

[newto914s]

(IMG:style_emoticons/default/agree.gif)

[Jake Raby]

2056cc safely. I have proven this time and time again, past 2056 lean conditions exist around peak torque and altered CR and camshafts can't make up for it..

Listen to my 4th dimension show from two weeks ago to hear more about it with Ray Greenwood, a D and L jet specialist.