discussing audi mods with solo ontario organizers
09-25-2003, 05:45 AM
#1
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discussing audi mods with solo ontario organizers
came around to the turbo discussion.
anyone have comments on this?
"
hi william,
just for fun i plotted your engine on a t3-60 compressor map...which i am told is the t28 compressor that is used..this should be enlightinging...
your engine is 109ci and i used a max rpm of 6500rpm(if its higher the problem only gets worse) and a VE of 85% (volumetric efficiency..i figure its a good head on your car)
so...
109cix6500rpmx0.5x85%ve/1728=174 base CFM of air
14.7+25/14.7= 2.70 pressure ratio...
100% rpm=174x2.70=470cfm
50%rpm=87x2.70=234.9cfm
the conversion from cfm to lbs per min is 14.5...so
your turbo needs....32.4lbs at 100%rpm and 16.2lbs at 50%
i now plotted this on the compressor map (see map)
and what do we find...voila....your turbo basically ends up in the CHOKE region of the compressor map....your turbo is basically a useless heat pump at the parameters you are asking it to work in....
also at 25psi your engine should be laying down around 295rwhp based on the CFM
this is a simplified calculation..not taking into account VE changes thru the rpm..or atmospheric density changes....but it clearly shows my point...
post this on your audi board and see what they say...if this is what the best audi tuners are doing (using t28's at 25psi)....you need to find new tuners....
adam
<img src="http://1.8t.org/~vk/misc/t3-60.jpg">
"
anyone have comments on this?
"
hi william,
just for fun i plotted your engine on a t3-60 compressor map...which i am told is the t28 compressor that is used..this should be enlightinging...
your engine is 109ci and i used a max rpm of 6500rpm(if its higher the problem only gets worse) and a VE of 85% (volumetric efficiency..i figure its a good head on your car)
so...
109cix6500rpmx0.5x85%ve/1728=174 base CFM of air
14.7+25/14.7= 2.70 pressure ratio...
100% rpm=174x2.70=470cfm
50%rpm=87x2.70=234.9cfm
the conversion from cfm to lbs per min is 14.5...so
your turbo needs....32.4lbs at 100%rpm and 16.2lbs at 50%
i now plotted this on the compressor map (see map)
and what do we find...voila....your turbo basically ends up in the CHOKE region of the compressor map....your turbo is basically a useless heat pump at the parameters you are asking it to work in....
also at 25psi your engine should be laying down around 295rwhp based on the CFM
this is a simplified calculation..not taking into account VE changes thru the rpm..or atmospheric density changes....but it clearly shows my point...
post this on your audi board and see what they say...if this is what the best audi tuners are doing (using t28's at 25psi)....you need to find new tuners....
adam
<img src="http://1.8t.org/~vk/misc/t3-60.jpg">
"
09-25-2003, 06:11 AM
#5
and your point is????
yes the point plotted on the right is correct, but the one on the left is a theoretical (would be nice, but not possible)...
On the APR kit we make 20-23 max
Some points on that map for reference based upon what I have logged
17.2 Airflow, 2.35 P ratio (3500 rpms @ 20psi -full spool)
31.5 Airflow, 2.35 P ratio (6500 rpms)
We are fully in the bounds of the map. APR has said many times there isn't really any more room with the turbo to go higher.
I hope the T-28 kit isnt pushing out that level of boost....otherwise yes it is a heat machine.
I've see GIAC tune some 23-26 psi chips for K03s so I know it has been done....
On the APR kit we make 20-23 max
Some points on that map for reference based upon what I have logged
17.2 Airflow, 2.35 P ratio (3500 rpms @ 20psi -full spool)
31.5 Airflow, 2.35 P ratio (6500 rpms)
We are fully in the bounds of the map. APR has said many times there isn't really any more room with the turbo to go higher.
I hope the T-28 kit isnt pushing out that level of boost....otherwise yes it is a heat machine.
I've see GIAC tune some 23-26 psi chips for K03s so I know it has been done....
09-25-2003, 06:46 AM
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if you're hittning 25psi, there is something wrong with your setup...those calcs should have been
done with something around 20psi like WJM showed. Work the numbers out yourself...
You are even in an ok efficiency circle of the compressor at 20psi redline...it could be better though<ul><li><a href="http://www.wrxfanatics.com/index.php?act=ST&f=43&t=1597&">http://www.wrxfanatics.com/index.php?act=ST&f=43&t=1597&</a</li></ul>
You are even in an ok efficiency circle of the compressor at 20psi redline...it could be better though<ul><li><a href="http://www.wrxfanatics.com/index.php?act=ST&f=43&t=1597&">http://www.wrxfanatics.com/index.php?act=ST&f=43&t=1597&</a</li></ul>