Power from Forced Induction
Power from Forced Induction this graph demonstrates the maximum cylinder pressure developed by 2 Atm. Forcing 2 bars in only increase the max cylinder pressure by 20%, but the torque is over doubled past 60 degrees.
this is from Maximum Boost: Designing, Testing, and Installing Turbocharger Systems (Engineering and Performance)
by Corky Bell
Would this not suggest that a higher SCR on a FI application is more effective given the same flow? Lowering the CR would lower cylinder pressure (less effective power).
The reason I bring this up is, with a small blower such as the MP112 Eaton (magnacharger), would you not want to max the compression in order to utilize the limited flow? lets assume that we can handle the detonation with chemical or mechanical cooling.
hopefully this is appropriate in this august forum.
this is from Maximum Boost: Designing, Testing, and Installing Turbocharger Systems (Engineering and Performance)
by Corky Bell
Would this not suggest that a higher SCR on a FI application is more effective given the same flow? Lowering the CR would lower cylinder pressure (less effective power).
The reason I bring this up is, with a small blower such as the MP112 Eaton (magnacharger), would you not want to max the compression in order to utilize the limited flow? lets assume that we can handle the detonation with chemical or mechanical cooling.
hopefully this is appropriate in this august forum.
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From: K-W, Ontario
You might be confusing effective compression with combustion pressure.
The graph you have posted displays combustion pressure.
If the SCR/DCR is too high for the extra charge given by the turbo, the fuel
would self ignite from extreme pressure/heat (pre spark).
I think this is where the VE/Torque peak comes into play. Maximum compression
for the most efficient point in the VE curve.
Unless you increase the octane, or fuel type as you suggested, raising compression
too much will give you problems.
The graph you have posted displays combustion pressure.
If the SCR/DCR is too high for the extra charge given by the turbo, the fuel
would self ignite from extreme pressure/heat (pre spark).
I think this is where the VE/Torque peak comes into play. Maximum compression
for the most efficient point in the VE curve.
Unless you increase the octane, or fuel type as you suggested, raising compression
too much will give you problems.
Last edited by Adrenaline_Z; Jan 26, 2006 at 06:21 PM.
Originally Posted by Adrenaline_Z
You might be confusing effective compression with combustion pressure.
If the SCR/DCR is too high for the extra charge given by the turbo, the fuel
would self ignite from extreme pressure/heat (pre spark).
.
If the SCR/DCR is too high for the extra charge given by the turbo, the fuel
would self ignite from extreme pressure/heat (pre spark).
.
SCR/DCR is this a relationship?, are you suggesting that if I increase the DCR the engine will be less prone to detonate?
Knowing the inlet temperature and pressure we can calculate the charge temperature at TDC using the CR and manifold pressure. Would you use the SCR or the DCR to determine the temperature of the charge and then have a predictor for detonation?
Corky's other book about superchargers, "Supercharged!", talks more about this in Ch. 3, The Physics of Producing Power, and Ch. 4, The Balance of Heat. It basically comes down to how much heat is added to the incoming air. A very worthwhile book. Talks about Roots, Centrifugal and Twinscrews.
Jim
Jim
Originally Posted by billc5
Would this not suggest that a higher SCR on a FI application is more effective given the same flow? Lowering the CR would lower cylinder pressure (less effective power).
The reason I bring this up is, with a small blower such as the MP112 Eaton (magnacharger), would you not want to max the compression in order to utilize the limited flow? lets assume that we can handle the detonation with chemical or mechanical cooling.
The reason I bring this up is, with a small blower such as the MP112 Eaton (magnacharger), would you not want to max the compression in order to utilize the limited flow? lets assume that we can handle the detonation with chemical or mechanical cooling.
If you're absolutely restricted, then you must increase efficiency, and more static compression is a good way.
You may become detonation prone in some area or areas of your operating range, like your torque peak as was mentioned. You would have to adjust your tune to cover this.
I found a link for a DCR calculation
http://www.rbracing-rsr.com/comprAdvHD.htm
but this still wont relate to the efficiency of the engine and it’s propensity for detonation.
A few posts have suggested that squish volume and area can be optimize by
a thinner head gasket for the squish volume and
milling the head for more squish area and higher compression.
My guess is, to take a 243 (LS6) casting to 11:1 SCR we would need to allow .005 for the thinner gasket and .015 for milling. PVC should be OK?
Does this seam like a reasonable strategy to increase efficiency?
http://www.rbracing-rsr.com/comprAdvHD.htm
but this still wont relate to the efficiency of the engine and it’s propensity for detonation.
A few posts have suggested that squish volume and area can be optimize by
a thinner head gasket for the squish volume and
milling the head for more squish area and higher compression.
My guess is, to take a 243 (LS6) casting to 11:1 SCR we would need to allow .005 for the thinner gasket and .015 for milling. PVC should be OK?
Does this seam like a reasonable strategy to increase efficiency?
Originally Posted by billc5
A few posts have suggested that squish volume and area can be optimize by
a thinner head gasket for the squish volume and
milling the head for more squish area and higher compression.
My guess is, to take a 243 (LS6) casting to 11:1 SCR we would need to allow .005 for the thinner gasket and .015 for milling. PVC should be OK?
Does this seam like a reasonable strategy to increase efficiency?
a thinner head gasket for the squish volume and
milling the head for more squish area and higher compression.
My guess is, to take a 243 (LS6) casting to 11:1 SCR we would need to allow .005 for the thinner gasket and .015 for milling. PVC should be OK?
Does this seam like a reasonable strategy to increase efficiency?
PVC is completely camshaft dependant.
