This post covers a lot of the material mentioned in follow ups..... First
off one of the biggest reasons for a turbo instead of a supercharger in a
16v car is packaging. Some of the roots style blowers will fit but they
require a lot of modification to the intake manifold and such. Centrifugal
blowers are easier to package but almost without question will require an
engine management change due to the new flow paths. Turbos, at least in our
kits, fit without modification to the car. The OEM engine management can be
retained (to a point 8^) lowering the overall price.
Turbo vs. supercharger is a tough debate. Some of the newer blowers
offer great efficiency and certainly longevity. Parasitic losses will be
greater with a blower, however the centrifugal blowers have low power
requirements compared to roots style blowers. Roots blowers typically can
make boost just off of idle whereas a centrifugal builds with RPM and
throttle position. This translates to a soft top end with a roots blower
because of lower efficiency and a soft bottom end but near turbo efficiency
with a centrifugal blower. How does a turbo compare? Well interestingly if
properly sized for reasonable power goals a turbo can almost match the low
end of a roots blower (our VR6 turbo kit has an 1100 rpm boost threshold)
while maintaining full boost over a very broad range (our 16V turbo makes
peak boost of 6psi from 2400-6500). What about lag. Forget it! Lag is
something a 76 930 has, not a properly engineered modern turbo system. With
huge amounts of progress in turbocharger technology and better engine
management coupled with higher compression ratio's lag is something that you
may only find in 5th gear at 1200rpms!
Heat can be a problem if you are racing. On the street with the volume
of air flowing through the engine compartment you would be hard pressed to
maintain over 130 degrees (given 80 degree ambient) under hood with a turbo.
We've done back to back testing before and after turbo installs and rarely
have seen more than a 10 degree jump. What can be a problem are things
directly around the turbine housing (hot housing). Wiring, hose, whatever it
is if it's too close it will be cooked. Proper measures need to be taken
during the design phase to locate the turbo away from hazards. Also generous
amounts of heat shielding will solve just about any heat problem.
As for back pressure a common figure is 2psi of back pressure between
the turbine housing and exhaust valve for every 1psi of boost in the
compressor housing. This is applicable to OEM motors but a performance
oriented set up will lean closer to a 1:1.5 or 1:1 ratio. Best of luck
Joshua Murray
Matrix Engineering
877.290.0661 orders
503.691.1541 tech
[email protected]
-----Original Message-----
From: T. Reed <[email protected]>
To: A2_16V list <[email protected]>
Date: Tuesday, January 25, 2000 7:55 PM
Subject: Turbo vs Supercharger?
>
>Hi everyone,
>
>I know this may not apply only to 16v's, but not much lately on the list
>seems to, and it's a valid question.
>
>I have a basic understanding of how superchargers and turbos work, and
>from my understanding superchargers create boost from idle, whereas turbos
>have a bit of lag before they kick in their power. So why use a turbo if
>the supercharger is a better performance option? Possibly because you can
>run more boost? But there's so much extra hot gas running around in the
>engine bay that there must be a big enough difference to make people do
>this other than the cost.. If someone would let me know that would be
>cool. I have been intending the VR6 swap (once I can afford it, and other
>car to drive in the process), and I was reading Euro car this month, and
>Momentum motorsports seems to think (or maybe they built it - not sure)
>that a 1.8T will build 330hp with the right mods, and a VR6 with a
>supercharger will get about 265 max. How does this work?
>
>Thanks,
>
>--Tyson
>88 16v GTi
>& empty wallet
>
>_____________
>List Sponsor: http://www.netsville.com
>To remove yourself from this list, send mail to [email protected]
with 'unsubscribe a2_16v' in the body of your message
>See us on the web at http://www.a2-16v.com
>Visit the 16V Homepage at http://www.gti16v.org
>
_____________
List Sponsor: http://www.netsville.com
To remove yourself from this list, send mail to [email protected] with
'unsubscribe a2_16v' in the body of your message
See us on the web at http://www.a2-16v.com
Visit the 16V Homepage at http://www.gti16v.org
