Mazz Bi-Turbo

Frederic Breitwieser frederic.breitwieser at xephic.dynip.com
Fri Jul 3 01:05:52 GMT 1998


Howdy Espen.  Sorry for my delay in writing, been one heck of a week!

>I have been thinking along the same lines the last days.I am planning to
>uppgrade my Maserati v6 2.5l biturbo projekt .I t has a Electro motive tec1
>Efi with "super"  software.320ccm bosch injectors.The engine is oddfier.So

I had my girlfriend look through my library of books today, but we couldn't
find what I was looking for - I have a car book somewhere that has a
buildup on the Maserati 2.5L Bi-Turbo.  Or a magazine.  I remember... I think.

Anyway, to respond to your issues, you do in fact have several choices.  I
think the easiest is to obtain, fabricate, or devise an adjustable fuel
pressure regulator - whereby the fuel pressure increases with the boost
level.  This will give you a sliding scale of fuel quantity into the engine
based on boost.  There's another mailing list I'm on that supports the
Buick Grand National, a V6 Turbo Regal-like vehicle.  A lot of those guys
run variable fuel pressure regulators with great success.  Sizing it to
your car might be a pain in the ass, and getting the springs right, but its
probably less agrevation than re-wiring the engine compartment.

>tought of using two maf systems like you have tried.GM ecus? I tought of

Since you are using the Tec I Electromotive system, I would highly
recommend NOT going to an OEM ECM like the GM.  I believe the Tec I has a
driving wire for a 7th injector - whereas you can shove one giant injector
into your intake manifold before all the other injectors, and have it kick
in at say... 3500 RPM, or whatever suits you.  If this doesn't work for
you, I know as the fact the Tec II electromotive product can do this very,
very well, and can adjust the 7th injector's output with the level of boost.

Another option, and more difficult to tune, (get your soldering iron out)
is to create a voltage to frequency converter (a LM9400 or maybe a 555
timer if you are creative).  Then, as your boost pressure increases, the
circuit increases its frequency output, which drives a Mosfet, which drives
the 7th injector.  I promised several people a schematic like this, however
I am slow getting to these things.  My job drastically interferes with
things that are important - like cars and schematics :)

>each runner.(If the size of the injector is adjusted by an increase in
>lift,then  two small injectors 
>must be faster than one big?)I think the Electro motive system is not very

Bigger injectors tend to respond slower to the applied voltage, but only
noticable at higher RPMs, because the mass of the valve is increased.  THis
difference is very small, and at 4500-5000 or less, you probably wouldn't
notice it.  However, your mileage might vary.

I chose to devise a system with two injectors per cylinder because I felt
the following list are advantages:

1. Smaller, OEM injectors are everywhere in junkyards.  Buy 20 and match 12
(for a V6) that flow the same.
2. Bigger injectors usually result in a crappier idle, depending on your
ECM and how it compensates.
3. I *wanted* to be radical :)

>user frendly(the "super" software)The car is so fast at the current ,its
>impossible to

I would agree. Their software is not overly user friendly, but its gotten
better.

>When back pressure is higher than boost you dont need sequential efi
>anymore...maybe you have a nice solution?                                  

The absolute BEST exhaust with a turbo vehicle is no exhaust.  The more
back pressure you have the slower the turbos spin up to full speed (unless
they are very small turbos).  And interesting property of turbos, is they
actually muffle the exhaust noise and reduce heat post turbo, therefore the
installed mufflers don't have to be as restrictive.

>                       Same fantasy!: Mine is F1 car with 4.2l Audi v8
>engine and transmision, with biturbo and street legal.....Must be the
>ultimate toy....:-)   

I haven't built it yet.  So far I have the engine done (v6, twin turbos,
480 HP and the block held together), with two injectors per cylinder.  The
chassis needs a tad more welding (like 2 years worth at this rate)

>Why bother when you have turbo? (you can aim for tuning the pipes to give
>you 

Why bother?  Because 10 percent is 10 percent !!!  

> (maybe I could get some  english spell check?)    

That's okay, I understood you just fine.


Frederic Breitwieser
Bridgeport, CT 06606

Homebrew Automotive Website:
http://www.xephic.dynip.com/

"When in doubt, use a bigger hammer"
-



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