Supercharger

Originally posted by T4 Primera
P10DET,
No Argument, a more efficient compressor will have a polytropic compression curve that is closer to an isothermal compression curve than a less efficient one. Unfortunately the compression happens so rapidly in this case that both types of compressor will be pretty close to an adiabatic compression curve anyway


Not true.

Rob Cadle, an engineer for Garrett posted some calculations on the SE-R mailing list for typical turbo and SC efficiencies. Actually, it may have been Mike Kojima. Anyway, the typical SC compressor outlet temps were significantly higher.

Originally posted by T4 Primera
T.O.O. is talking about the heat stresses associated with the increased back pressure between the exhaust valve and the exhaust port outlet. Increase pressure = increase temperature. Intercooling is irrelevent to the exhaust temperature induced stresses. So you can keep your double helping :D Did you actually read the link before dissin' it ??


He may be talking about just the exhaust side, but overall, you cannot dismiss the thermal stress from the higher intake temps (for a given boost) for a SC.

Originally posted by T4 Primera
Just off the top of my head, the pressure drop/temperature drop can occur BEFORE the compressor


We were talking about intercoolers (TOO said their IC could cool the air temp below ambient). Other than an water-air IC filled with ice water, you are not going to lower the temp at the outlet of the intercooler below ambient. And you're not going to lower your pressure in the IC.

Originally posted by stoneage_tech
why do you think you only see blowers on nhra funny cars and top fuel dragsters ?i dont think john force wants to wait around for the boost to arrive 3rd class mail......


Because the rules forbid turbochargers.

P10DET,
Rob Cadle, an engineer for Garrett posted some calculations on the SE-R mailing list for typical turbo and SC efficiencies. Actually, it may have been Mike Kojima. Anyway, the typical SC compressor outlet temps were significantly higher. Thanks for that, I'll look it up. (I need to polish up the maths anyway:) )We were talking about intercoolers (TOO said their IC could cool the air temp below ambient). Other than an water-air IC filled with ice water, you are not going to lower the temp at the outlet of the intercooler below ambient. And you're not going to lower your pressure in the IC. It'll be interesting to find out how T.O.O.s system works then. I have seen some recent developments in thermoacoustic heat pumps at http://www.lanl.gov/mst/engine/ that may be the method T.O.O. is using.

Found the info on the Turbodyne site that stoneage_tech posted very interesting. Seems to combine the best of both systems. Wonder how the costs will stack up though - looks expensive:( .

Originally posted by T4 Primera
P10DET,
Thanks for that, I'll look it up. (I need to polish up the maths anyway:) )

I'll try to find it as well. I tried half-heartedly last night but it was late. IIRC, the number was rather hair raising. My recollection was that I was shocked by the difference.

P10DET,
Read about 60 posts on the subject in the se-r mailing list. Didn't find specific calcs but saw enough to see it's obvious that the sc does indeed heat the intake charge more than the turbo Hence more air mass for a given boost pressure from a turbo.
Biggest reasons are lower adiabatic efficiency of the non-centrifugal sc due to rotor tip/end leakage, the added churning effects of the rotors and the shearing of air as the rotor passes the edge of the sc inlet tract. Intake charge temperature differences ranged between 100-150 degrees.:eek: I presume this is Farenheit (they don't say) so thats about 40-65 degrees Celsius. Later on (when I've revised my physics notes) I'll do some calcs to see what this equates to in terms of mass air or horsepower.
Thanks for the reference Geo.:D There really is a wealth of info in that mailing list.