Francois
Thank you Francois. That is the best information we have on the stock
turbo
so far. Now what is that rule of thumb on turbine RPM? Here it is in
the Macinnis book on page 105. 2% increase in RPM per 1000 feet. 20%
faster RPM for 11,400 feet or 126,000 RPM. That combined with a couple
hundred degrees hotter exhaust ought to do the job on the turbine.
230 HP at .5 BSFC is 115 pounds of fuel per hour or 1.9 pounds of fuel
per minute. At 14.7 to one stoechemetric (s?) that is 28 pounds of air
per minute. My guess is the pressure ratio is about 1.2 to 1.4.
Looks like we are well off in the right regions of the T3 "60"
trim compressor map at 1400 feet. The super 60 trim is about the best
we can do in the T3 size but not good enough. So it is going to take a
TO-4 compressor wheel. That is possible and is known as a hybrid in
Turbonetics speak.
A larger compressor wheel should slow the RPM and put the stock turbo
in a more efficient place on the compressor map. My guess is a TO-4
"40" trim if that is mechanically possible. Perhaps it is also possible
by souping up the stock compressor housing.
I will attempt to measure the A/R ratio of the stock turbine
housing to get a better feel for just what this turbo is equivalent
to in Garret turbos.
Paul Lamar
Paul and Francois,
I know you wanted to test the possibility of stock Mazda turbos, but now
they have failed we may need to fall back on information given in past
postings.
My past notes indicate a TO4E-50 ( 50 trim compressor), with P trim exhaust,
with modified 1.3AR ratio housing- turbine wheel Inconel.
Intercooler Spearco ( small)
Boost 6.4 psi@ 6,500 RPM ( 43 " manifold pressure)
Boost control -Turbonetics " Deltagate".
Additional info gathered indicated AR inlet as .6, AR exhaust .96.
It pays to keep notes - hope it helps.
George (down under)
Plotting Francois's data on the TO4E-50 trim map is the intersection of the green
and the red line. To keep the air flow constant as one gains altitude
means you move straight up on the green line... roughly.
You can roughly identify the stock Mazda compressor by measuring the wheel
and comparing it to this chart.
Paul Lamar
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/
Copyright 1998-2004 All world wide rights reserved.
