Turbo Maps
Posted: Thu Oct 27, 2005 3:56 pm
Anyone able to explain how to read these, or check my poor turbo math
I'm interested to see because in looking for another kkk K26 a good KKK K27 has turned up and with my limited understanding of these turbo maps i think a K27 might work?
here are the maps:
and the K27
Heres my poor turbo math
Estimated pressure ratio is 1.54
Boost press req'd is .54 x 14.7 = 7.9psi
Density ratio 1.54(to the power of .28 )-1 x 550*/.75= 94 degreesF
intercooled desity ratio say 85% efficient thefore temp gain 94 x (1-0.85) = 14*F temp gain
Desity ratio intercooled 460*F+90*F/460 + 104*F = 97.5 = 2.5%density loss
intercooled press ratio = 200hp/130hp x 0.975 x 1.25 x 0.90 = 1.395
CFM 120cidx 5400rpmx 0.5 x 0.8Ev/1728 = 150CFM (stock engine)
Req'd Intercooled CFM 1.395 x 150 = 209 CFM
Turbo peak efficiency wanted around 25% higher than peak torque say 4000rpm + 25% = 5000rpm
new cfm = 139(stock) x 1.395 = 194CFM required
194/14=13.84 pounds per min ( to read turbo map)
Once you've picked yourself off the ground from laughing so much please let me know all the mistakes
I think these CFM figures are too high?????
Is 80% volumetric efficiency about right for alfa 4 cylinder (nord)
Can i use a drive power effiency of 90% for a turbo?
the K27 seems to be very efficient at 77% and 75%, more than K26?????
Thanks Matt
I'm interested to see because in looking for another kkk K26 a good KKK K27 has turned up and with my limited understanding of these turbo maps i think a K27 might work?
here are the maps:
and the K27
Heres my poor turbo math
Estimated pressure ratio is 1.54
Boost press req'd is .54 x 14.7 = 7.9psi
Density ratio 1.54(to the power of .28 )-1 x 550*/.75= 94 degreesF
intercooled desity ratio say 85% efficient thefore temp gain 94 x (1-0.85) = 14*F temp gain
Desity ratio intercooled 460*F+90*F/460 + 104*F = 97.5 = 2.5%density loss
intercooled press ratio = 200hp/130hp x 0.975 x 1.25 x 0.90 = 1.395
CFM 120cidx 5400rpmx 0.5 x 0.8Ev/1728 = 150CFM (stock engine)
Req'd Intercooled CFM 1.395 x 150 = 209 CFM
Turbo peak efficiency wanted around 25% higher than peak torque say 4000rpm + 25% = 5000rpm
new cfm = 139(stock) x 1.395 = 194CFM required
194/14=13.84 pounds per min ( to read turbo map)
Once you've picked yourself off the ground from laughing so much please let me know all the mistakes
I think these CFM figures are too high?????
Is 80% volumetric efficiency about right for alfa 4 cylinder (nord)
Can i use a drive power effiency of 90% for a turbo?
the K27 seems to be very efficient at 77% and 75%, more than K26?????
Thanks Matt