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From: allgair@fritz.UUCP (Ed Allgair)
Newsgroups: net.auto
Subject: Re: superturbochargers
Message-ID: <2518@fritz.UUCP>
Date: Thu, 18-Apr-85 15:40:48 EST
Article-I.D.: fritz.2518
Posted: Thu Apr 18 15:40:48 1985
Date-Received: Sun, 21-Apr-85 06:05:49 EST
References: <1335@shark.UUCP>
Reply-To: allgair@<1335@shark.UUCP>.UUCP (Ed )
Organization: FileNet Corp., Costa Mesa, Ca.
Lines: 55
Summary: 

In article <> davew@shark.UUCP (Dave Williams) writes:

 >Early turbochargers suffered from
 >a hp lagging effect which meant that the boost generated by
 >the unit started to come on at some point, usually as much as .5
 >sec after the throotle was opened. Improvements in rotor design
 >have taken care of this problem.

Isn't 'turbo lag' mostly caused by the distance the turbo's compressor is 
from the intake valves? Also the distance from the exhaust valves to 
the turbine side? I thought that shortening that path was the point 
of trying to make the turbo housing a part of the exhaust manifold and 
keeping the intake as direct as possible. (And a low volume to compress.)

Also, my 1985 2.2 turbo has a definite turbo lag of sometimes greater
than .5 second. This lag is most noticeable at about 25 mph if I floor
the accelerator, but is also quite noticable if I only depress the 
pedal partway and hold it. In the partway depressed case, the car will
immediately accelerate, (no stumbling) then if you listen you can hear
a whine as the turbo spins up, accompanied by a power increase beyond
what would be expected for the 200 - 300 rpm increase that has happened.
(not that I'm dissapointed when the power arrives :-) )

I understand that my car has a wastegate that is 'computer controlled'
(as opposed to strictly boost controlled). Could this be playing
"economy" games with my turbo, thereby increasing the percieved 'lag'?

I'm not on boost continuously until I'm doing about 65 mph, determined by
keeping track of whether the last whine was a 'whine-up' or a 'whine-down',
so I still can detect lag below that speed. Above 65, I feel no delay from 
accelerator position to engine action. It's somtimes hard to seperate the 
auto trans workings from the turbo's at in-between speeds, so these 
observations are either first-gear or top-gear. On the freeway, the 
transmission completes its down-shift before the boost surge hits.

 >...are variations of roots or centrifugal designs. It takes about 35-50 hp
 >to drive a supercharger and the boost is always there, so engine wear...

Does it take that much power to drive any supercharger? I heard about a 
company in Los Gatos that has come out with a supercharger for the
Honda V65 motorcycle. They claim 170 hp instead of stock 112 hp. Does
that mean the supercharger takes away 35 hp and gives back 93 hp? Or
do some smaller(I assume smaller for the smaller displacement here)
superchargers use considerably less power? No contest on the increased
engine wear -- you've got to pay for it somehow. :-)

What about superchargers and fuel-injected cars? How would a turbo or
superchager work on all these new-fangled 'port-injected' or 'cross-fire
injected' and other injection systems that have a zillion sensors feeding the
control computer? If they weren't designed for it originally,(come from the 
factory that way) would it be nearly impossible do add one?

Hmmm...Yes, let's discuss superchargers! :-)

Ed Allgair