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volumetric efficiency of N/A, SC, TC, and twincharged L67

SgtMarshal

SgtMarshal

Active member
does anyone know how to calculate the volumetric efficiency of a L36, an L67, a turbocharged L67 and a twincharged L67? I know there is a formula for it, but even if I knew what the formula was, it would probably be beyond my simple algebra education.

I'm curious about calculating the volumetric efficiency of a 3800, a 3800 that is supercharged and a 3800 that is both supercharged and turbocharged? I got in an argument with a guy on facebook about twincharging and now I'm curious about the science behind the efficiency/inefficiency of the above mentioned engine combinations.

my theory is that the turbocharged 3800 will have more volumetric efficiency
 
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http://installuniversity.com/instal...etric_efficiency/ve_computation_9.012000.html

you don't need the stock MAF sensor but you do need one that reads and is scaled properly so that when the computer commands 11 to 1 afr. or 14 to 1 AFR the wideband agrees with it. even then this is still more of a rough estimate.
this means that you can't lie to our PCMs like we normally do when we max out the mass air flow scale. by telling it that the injectors are smaller and therefore the air flow its receiving is smaller which tricks the PCM into thinking that we are flying less than 511 grams per second
 
will the supercharger decrease the efficiency of a twincharged engine because of the energy required to operate it?
 
It is.
Less parasitic losses the better.
Crank driven robs usable power...exhaust driven is recovering thermal energy that is usually wasted.
 


I went full retard last night on a dude who was extolling the virtues of a twin charged car, and ended up deleting a lot of my comments
 
a twin charged car is a crutch for too large of a turbo that spools slowly due to lack of exhaust volume. the SC helps grunt up the bottom end but then becomes a drag up top as it falls off in pumping efficiency as the turbo reaches its.

not a problem nowadays with VNT turbines allowing for the best of both worlds with a turdbo.
 


Turbocharged400sbc said:
a twin charged car is a crutch for too large of a turbo that spools slowly due to lack of exhaust volume. the SC helps grunt up the bottom end but then becomes a drag up top as it falls off in pumping efficiency as the turbo reaches its.

not a problem nowadays with VNT turbines allowing for the best of both worlds with a turdbo.
Click to expand...

that's what I was trying to say last night, but I couldn't see past the red, and all that really came out was that the supercharger helps with low and mid power, but when the turbo starts taking over, the supercharger gets in the way. I suggested a clutch should be used to disengage the supercharger when the turbo took over, but the cost of a clutch is going to be excessive.
 
your just better off using nitrous to spool/overcome bottom end lag....at least then your getting chemical intercooling while your dumping in the additional air/fuel to increase turbine drive pressure faster
 
i have fun with my twincharged gtx. What kind of power loss would i possibly encounter when the bbv opens at 8ish psi and turbo takes over? Its street manners leave nothing to be desired, as power is always there. Its just a blast to drive.
 
you have to understand that the roots is just heating and recirculating the air.

its a positive displacement blower, your moving 90ci per revolution, bbv open or not, since you open the bbv so the blower is no longer building pressure, the bbv is now recirculating the air from the rotor blades. they may not be working hard but they are creating friction and rotational drag as your forcing the blower to recirculate through a rather small god damned opening, that thing should be about 3" in dia or larger for it to minimize the blower idle losses from air recirculation...though you wont do much for the rotational losses.

the extra weight is another compromise of a twincharged system

might as well let it compound.....
 


meh, i can live with all that :th_biggrin1: She made just over 500wheel last dyno, running 3-4psi more now. Its all about the fun.
 
SgtMarshal said:
does anyone know how to calculate the volumetric efficiency of a L36, an L67, a turbocharged L67 and a twincharged L67? I know there is a formula for it, but even if I knew what the formula was, it would probably be beyond my simple algebra education.

I'm curious about calculating the volumetric efficiency of a 3800, a 3800 that is supercharged and a 3800 that is both supercharged and turbocharged? I got in an argument with a guy on facebook about twincharging and now I'm curious about the science behind the efficiency/inefficiency of the above mentioned engine combinations.

my theory is that the turbocharged 3800 will have more volumetric efficiency
Click to expand...

A toss up, I was thinking about it too; generally speaking exhaust backpressure will be higher in this engine (turbocharged 3800) versus a compound system running in series, hmmmn but then there is slippage, parasitic loss and some leakage from the blower. I think if we held ever thing constant, the compound engine will definitely be more efficient than with just the turbo alone...backpressure is simply a huge deal imo
 
Turbocharged400sbc said:
your just better off using nitrous to spool/overcome bottom end lag....at least then your getting chemical intercooling while your dumping in the additional air/fuel to increase turbine drive pressure faster
Click to expand...

There is a guy here in los angeles using a dual turbine housing setup on a huge wheel to combat lag, pulse turbocharging he called it?!?! Now it seems this may lower the post turbine backpressure
 
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