nitrous or turbo?

[Jorgen Karlsson]

Todd Young wrote:

> Or you could "fabricate" your own system using a Powerdyne
> supercharger and a
> serperate computer to control basic injection:
> http://www.powerdyne.com/
> http://www.electromotive-inc.com/products.htm#tec

First of all, an electromotive system won't work on a five cylinder engine,
only a few aftermarket system does.

Haltech, EMS, Autronic, Motec and Perfect Power can do five cylinder
engines. All but Perfect Power is made in australia, PP is made in South
Africa. Autronic and Motec can also do direct spark on a five cylinder.
Rumors say that the new Accel DFI 2000 will work on a ten cylinder engine,
that would automatically make it work on a five cylinder engine.

Motec is _very_ expensive, starts at $4000. Perfect Power is the cheapest.
EMS and autronic are mid priced at around $1500, Haltech E6S should be
around $1200. All but perfect power can use a wide band lambda sensor but
that adds around $1000 to the price in all cases but the EMS where the
lambda upgrade are around $300.

The EMS is very easy to tune but lacks closed loop operation, that is not
really a problem, when the car is properly tuned the car runs better in
closed loop. It also has the benefit of both a handheld programming device
and a computer interface with modern windows software. Check
www.enginemanagementsystem.com for more info and a demo of their software.

Perfect power has a system called MIC3, it should be around $800.
www.perfectpower.co.za has lots of information. Something is strange with
this place, they have dropped a few of their products...

The best information about autronic is found on http://www.turbofast.com.au


Haltech has a new site now, still located at www.haltech.com, it even works
now!

www.motec.com is a good start if you want more info about Motec engine
management systems.

Finally I have to vent my dislike of the "superchargers have no turbo lag"
idea. Of course they don't but the one mentioned above are a centrifugal
blower, the boost characteristics is that the boost is proportional to rpm.
You don't hit maximum boost until redline! At 3000rpm on our cars we would
only have 3psi of boost if audi had chosen one of these instead of the
turbo... Nowdays they often use a recirculating valve or a blowoff on
centrifugal blowers to get rid of this problem, this usually means that they
rev the blower twice as fast as usual, using twice as much power as usual,
only to recirculate half of the air into the supercharger again at high
rpm... The efficiency is very bad when compared to a turbo charger even if
you don't count that half of the air is compressed twice. The efficiency is
a number that explains how much the copressor heats the air while
compressing it compared to the gas laws.

The roots superchargers are a joke, they use huge amounts of power and heats
the intake charge more then the onther types.

The screw type super chargers are nice, with full boost of idle and they are
actually pretty efficient, like a porly designed turbo system. The Swedish
autorotor is an example of a screw type supercharger. They don't use much
power to drive either.

If someone wonders why only roots type superchargers are used in dragracing;
screw type chargers are banned... I wonder why they changed the staging and
start procedure this year in the classes where turbo charged cars are
conpetitive... A ban of turbos would have been to obvious I guess...

Jorgen Karlsson
Gothenburg, Sweden.