Water Injection Thread /turbo turbin

Espen Hilde mwichstr at online.no
Wed Jan 6 00:33:34 GMT 1999




> > >Thanks, Greg, for the good discussion.  I never thought about the Mach
1
> >stuff in the exhaust housing.  At Mach 1, though, flow through a nozzle
is
> >only  >>
I have allso never thought about this point my self, thanks Greg.
I think that the design of manifolds must follow application.
in a regular standard car with backpressure exiding boost pressure at high
rpms, where you need fast spool up as possible I think your better of with
a manifold with as little volume as possible,without destroing the flow to
much.
This means little heat loss from manifold ,(fast spool up)When the exhaust 
has passed the turbin it can not do any negative backpressure work anymore.
There fore the small volume of manifold is a bennefit in the high
backpressure 
aria.At least I think it will work over a greater aria than the timing of
pulses in a tubular manifold.It would be interesting to discower how a
turbo with one turbin for each cyl.mounted just outside the exhaus outlet
of the engine head would work.As you say , the pulses will be strong and
evently break the mach 1 . many small turbines calls for high leakage
.maybe not a god Idee after all.
In a turbo aplication with focus on maximum output I would go for headers.
When the turbine is mached for max efficensy at high rpm.At what point 
do we want the pulses to help us?At the point just before the boost starts?
Long not isolated headers will lose a lot of the precius energy we have
when
we need it as most, when boost is starting , this means less efficient
aria, at high rpm this lost energy does not play a major role, maybe we
want it to cool the exhaust as much as possible , because we have to much
of it.(We have discussed earlier the possibility of insulating the inside
of the exhaust tubes....was it possible?)  What about using a twin entry
turbo and connect the two enties with an extra wast gate walve at the point
where backpressure exides boost pressure.This will increase the turbine
envelope,and that is the main problem 
with turbo chargers .The efficient turbine work aria is to small . Maybe
thats why chryslers turbine car was no sucsess. Garret has started
massproducing 
turbines with wariable nossle, you will not need a wastegate any more...
No more dumping of energy.
Many do a modification to the turbines( to expand their ranges?) some
cut/clip the wings on the outlet part of turbine wheel , some increase the
outlet circumference diameter to a bigger dimension than the turbine wheel.
Its a pitty that turbine efficency charts is difficult to get ,all I have
seen is compressor maps , their range of efficency is much greater.....
Backpressure will increase faster if you have a little turbine wheel with
the greatest nossle/exhaust hausing (mach 1 at more places on the way trou
the turbine?), then is better to have one of the smallest 
exhaust housings on a big turbine wheel, I think this gives you not the
best peek efficiency but a wider aria.
I have seen two stroke engines with tuned expansion cambers and turboes no
the end, tremendus output! Drag snowsleds with efi and tuned expansion 
cambers and turbo.....WOW
Maybe we must alter the engine to give a strong exhaust puls to take full
advantage of this in a 4 stroke.
With the hat safe on my head.(cone shape)
espen
Please run an english spell check before reading.....I dont have one.....it
shows......




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