L-Jetronic mods

[H Villemure]

Aaron,

Aaron Willis wrote:
> 
> My first post to this list -
> 
> HELP!! I am new to all this stuff. Basically I am trying to inject and
> possibly supercharge a currently carbureted engine. The engine is a
> Toyota 3T-C 

you mean you plan to work on the 3T-C? Do you have the engine code ok?
Cuz the 3T-C is a pushrod, carburated, single overhead cam engine. It
does not share all the very strong internals of the 3T-GTE.

>, puand the injection is a L-Jetronic system from a Toyota
> Corolla GT-S twincam.

>From the early 4A-GE??

> These are the stumbling blocks I have found:
> 
> 1. The injectors are 210cc each. I've read these are only good for 30
> horsepower each, four injectors = 120 hp. I do have eight injectors. Can
> I use them all?

By this arithmetic, it would be impossible to extract more than 167.some
hp from the 5M-GE with stock 195cc/min. injectors. I have to disagree. 
Try 10 instead of 7 to get a likely, reliable hp figure on stock injectors.

> 2. The airflow sensor (flapper style) is tiny. Can I use one from a
> bigger Toyota or other car on the stock computer? Will that compensate
> for having eight injectors?

Yes you have to remain within the adjustability of your own Air Flow
Meter. Else you might find it very much easier to run a MAP sensor and
piggyback controller for mixture. Also, I do not know what exact AFM
resides in your application, but a very knowledgeable Toyota modder
extracted 310 stable hp's out of his 3T-GTE on very stock afm and
throttle body. The air speed at intake makes this into a
not-so-important issue.
What is important though is to stay within proportionality of your AFM.
For instance there is a way to enhance output in the 7M-GTE by using the
V-8 Lexus AFM instead of the stock one, coupled with 560 cc/min.
injectors instead of 440. But the Lexus afm happens to send the *same*
type of signal, has an exactly 25% larger body, and still there is some
splicing to do. I do not know if there is a sibling to yours.

> 3. The computer gets its RPM signal from a sensor in the distributor,
> which my dixxy doesn't have. Do I have to make it fit in my dizz or can
> I use a crank wheel instead?
> 4. Or should I sell it all off and go programmable? I am trying to do
> this on a budget.
> 
I would go for another engine to start with. Later 4A-GE is a lot of fun
and goes for cheap. But then if you want to keep the 3T-C I would say it
will be easier to go for a programmable fuel/ignition ecu.

Just my 0.02
-- 
Helene V.
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