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Tofuball's '94 XFi; It's all about city MPG
Topic Started: Mar 12 2011, 08:59 AM (39,414 Views)
Tofuball
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Strange Mechanic

Geo Glenn is my hero.

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Coche Blanco
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Take another pic showing the difference better, thanks. (it'll help in future threads)
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todaugen


Tofuball
Mar 23 2012, 02:38 PM
Geo Glenn is my hero.

Hey hey hey there...he belongs to all of us :wub:
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t3ragtop
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Turbo3 and Twincam Tweaker

the other way to go for the 30mm cam gear is to use one from a g13b dohc 16v (swift gt engine.) those have the 2 alignment slots on the center like the thin one in your pic.
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Tofuball
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Getting there... Ground off two teeth on the dizzy and going to use that as the cam reset sensor for now.


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starscream5000
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Got 70 MPG?

Nice choice for the oil filter :thumb
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Tofuball
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starscream5000
Mar 26 2012, 06:48 PM
Nice choice for the oil filter :thumb
Heh, thanks. It's not the final setup, gonna run it like that for a bit but I have a remote mount kit and an oil cooler I'm going to hook up.
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Tofuball
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Pulled the XFi harness . . .
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Unwrapped it . . .
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Here is a picture that illustrates the old style of BATCH injection . . . these are the three injector plugs from the turbo model, they all run off the same two wires, they all fire at once.
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Edited by Tofuball, Apr 1 2012, 03:47 PM.
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Coche Blanco
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How does that work? (batch fire)
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Tofuball
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Coche Blanco
Apr 1 2012, 04:00 PM
How does that work? (batch fire)
What part don't you understand? I'll try and explain, I'm actually halfway out the door on my way to work so I'll try and make this quick. It is very similar to our TBI (Throttle Body Injection)- I believe our TBI fires three times per cam rotation - the batch system may or may not do the same, however batch is much easier for a manufacturer to design, it only requires one injector driver channel, and no additional timing equipment on the engine or ECU (Engine Control Unit) besides the distributor.

The factory batch injectors have two "nozzles" in the pintle cap that spray on either side of the hot valve, like a hose. This helps the older style injectors get a smaller droplet size, better fuel-to throttle response (you can run leaner, smoother) and less fuel stuck to the walls of the intake manifold then a TBI.

To do timed sequential injection (the setup I am doing), the ECU has to know engine position with a much greater degree of accuracy. That is why I am using that toothed wheel (32 teeth, minus 2, minus 2, minus 2) for my crankshaft sprocket - it lets the ECU know where the pistons are. On top of that, I have a cam position sensor, made by cutting all but one tooth off the distributor. That cam position sensor, combined with the crank position sensor, allows the ECU to know engine position and speed well enough to be able to fire the injectors at the ideal time for whatever I am tuning for (power, economy, emissions, usually injector timing is used to tune for emissions or economy rather then power).

The results? Theoretically, smaller droplet size, even better fuel-to-throttle response, even less fuel stuck to walls, and (to some degree) intake charge shaping (choosing where in the piston charge the fuel concentration is)

And now I'm late for work. Bye!
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Tofuball
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Changed the front wheel bearings, wrote up a how-to if anyone wants to know how to change the 94 and earlier style bearings.

http://geometroforum.com/topic/4749908/1/
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Tofuball
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Starting to look like it belongs in a car . . .
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wanderling


What is the difference between an XFI engine and the engine in a regular metro, if any?
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Scoobs
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:D

wanderling
Apr 3 2012, 08:19 PM
What is the difference between an XFI engine and the engine in a regular metro, if any?
Camshaft and timing gear.
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Coche Blanco
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Scoobs
Apr 3 2012, 08:23 PM
wanderling
Apr 3 2012, 08:19 PM
What is the difference between an XFI engine and the engine in a regular metro, if any?
Camshaft and timing gear.
Camshaft and pistons.

ECU is too, if you count that.
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