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Discussion Starter · #1 · (Edited)
Just discovered some nice videos from Sector111...

Sector111 Educational Video: Roots Superchargers Components & Functions
Sector111 Educational Series: Supercharger Sizing Part 1
Sector111 Educational Series: Supercharger Sizing Part 2

One of the useful info provided is that the TVS R1320 is able to spin a bit north of 20k rpm and can boost up to 21-22 psi. Now that the A/W intercooler is being installed, I am really thinking of a smaller pulley...

Edit: Updated in order to include the two newer sizing videos
 

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A very nice video - I especially liked the CAD animation of the airflow. :thumbup:

I know you're engine is far from stock, but did you notice the scrolling text at the end - 'Guess which blower is too big for a stock 2ZZ'...

Despite that, I'd love to know how you'd get on with 20+ psi from your TVS - but I can't help wondering just how much wear all superchargers put on the crank bearings from all that extra loading.

The MP62's are pulling 20-30HP odd, how does that compare to the standard load on the aux belt - I know the alternator is only ~1.2HP, but I have no idea about the A/C and water/PS pumps :shrugs:
 

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Discussion Starter · #4 ·
I know you're engine is far from stock, but did you notice the scrolling text at the end - 'Guess which blower is too big for a stock 2ZZ'...
Yes, seen that! However, I think that this is said in context to stock compression ratio and stock pistons.

I can't help wondering just how much wear all superchargers put on the crank bearings from all that extra loading.
There's a bunch of people that race-track their car with the MP62 having a 2.5" pulley and had no issues with crank bearings from what I know of. If you consider that my car is a daily driver and occasionally goes above 6-7k rpm for the thrill of it, I don't think that this is going to be an issue...
 

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There's a bunch of people that race-track their car with the MP62 having a 2.5" pulley and had no issues with crank bearings from what I know of. If you consider that my car is a daily driver and occasionally goes above 6-7k rpm for the thrill of it, I don't think that this is going to be an issue...
Does that mean they've not had failures (yet) or that they've inspected their bearings at the end of a race season and not seen any excessive wear?

IIRC when I did my first engine build there was noticeably more wear on the bearings next to the crank pulley - which may be entirely normal anyway, but I was just wondering whether it might be due to the lateral forces from the heavily loaded aux belt. :shrugs:
 

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Discussion Starter · #6 · (Edited)
I really enjoyed these three Sector111 videos because they are very thorough and really give some idea about the concepts behind supercharging. I would really like to stand at a certain Powerpoint slide in these videos which is the following:



So let's see the facts here, make some assumptions, present some basic formulas, crunch some numbers and make some conclusions.

Facts
First, at a 75F day, the MP62 had an increase of 140F which totals at 220F of air temperature exiting the supercharger while at the same time the TVS had an increase of 205F which totals at 280F. Second, the MP62 outputed 7psi of boost and 675m3/hr of air while the TVS outputed 15psi of boost and 875m3/hr.

Assumptions
- We assume that engine setups between the MP62 and TVS are identical.
- The slide states that these measurements were taken in a 75F day but we do not have any info as to what was the actual air temperature entering the supercharger. Searching over the internet, I found this post: Thread: REVIEW: RLS 3-Chamber Shroud & Heatshield. There a guy says how happy he is when at a 71F day, he sees IAT temps of 82F when canyon driving with some kind of air temp heat shield. Having this in mind, it is safe to assume that on a 75F day, air temperature entering the supercharger would be 85F=545R (that is in the Rankine scale).
- Due to the air filter and throttle body, there is a certain amount of pressure drop so let's assume a value of 0.05bar (0.7psi) for sucking 675m3/hr (airflow of the MP62 setup).

Basic formulas
- Adiabatic compression of atmospheric air (oxygen/nitrogen mixture):

Tc=Ti*(Pc/Pi)^0.285

where Tc is the temperature of compressed air, Ti is the temperature of the air before compression, Pc is the pressure of compressed air and Pi is the pressure of the air before compression. Adiabatic compression is a process where there is no heat transfer taking place. For our case, this formula can calculate how much temperature rise would occur if our supercharger had 100% efficiency.

- Adiabatic efficiency:

e=(Tc-Ti)/(Tr-Ti)

where e is the adiabatic efficiency (which multiplied by 100 is converted to a percentage), Tr is the compressed air temperature as measured from the oultet of the supercharger and the other variables are as before (adiabatic compression equation).

- Darcy-Weisbach pressure drop equation

h=(f*(L/D)*V^2)/2g

where h is the actual pressure drop, f is a friction coeffiecient, L is pipe length, D is its hydraulic diameter, g is the acceleration of gravity and V is the amount of air flow.

Number crunching
- We assumed that the MP62 setup has an inlet pressure drop of hm=0.7psi because of the air intake system that it is attached to. By observing the Darcy-Weisbach equation, it is evident that pressure drop is rational to the square of air flow when all other factors stay the same. Since we assumed that engine systems are identical, we know that throttle body and air intake are identical for both setups. This means that the only thing changing from setup to setup is airflow. Using this equation, the TVS pressure drop is equal to:

ht=hm*(Vt/Vm)^2=0.7*(875/675)^2=1.176psi=0.081bar

This means that air pressure before the MP62 is Pim=14.5-0.7=13.8psi=0.951bar and air pressure before the TVS is Pit=14.5-1.176=13.324psi=0.919bar. From the slide we have that MP62 boost is 7psi which means that ABSOLUTE air pressure is Pcm=14.5+7=21.5psi=1.483bar while TVS boost is 15psi which means that ABSOLUTE air pressure is Pct=14.5+15=29.5psi=2.034bar. Combining these data with the adiabatic compression equation we have that for the MP62, air temperature for 100% efficiency would be:

Tcm=Ti*(Pcm/Pim)^0.285=545*(21.5/13.8)^0.285=619R=159F.

while for the TVS would be:

Tct=Ti*(Pct/Pit)^0.285=545*(29.5/13.324)^0.285=684R=224F.

From the slide we have that the measured MP62 temperature is equal to Trm=220F while for the TVS is Trt=280F. By applying these values to the efficiency equation we have for the MP62:

em=(Tcm-Ti)/(Trm-Ti)=(159-85)/(220-85)=54.6%

while for the TVS we have:

et=(Tct-Ti)/(Trt-Ti)=(224-85)/(280-85)=71.4%

Here are the efficiency maps as provided by Eaton:

M62 5th generation performance map
R1320 TVS supercharger performance map

If you check the maps, you will find out that our calculations are almost identical to what the maps suggest! Having said that, it would be really interesting to calculate what temperatures the TVS would output if we wanted it to produce an airflow of 675m3/hr. Consulting the map, we would see that for 1.56 pressure ratio and 675m3/hr air flow, the adiabatic efficiency is 73% (as opposed to the 54.6% of the MP62 that we have calculated). By solving for Trm at the adiabatic efficiency equation we have:

et=(Tcm-Ti)/(Trt-Ti)<=>Trt=(Tcm-Ti)/et+Ti=(159-85)/0.73+85=186F

Unfortunately we cannot do the same precise calculation for the MP62 flowing 875m3/hr since that amount of airflow is off charts. However, even if we consider an adiabatic efficiency of 54.6% (which to be honest is unrealistically optimistic) we would get:

em=(Tct-Ti)/(Trm-Ti)<=>Trm=(Tct-Ti)/em+Ti=(224-85)/0.546+85=186F=339.56F

Conclusions
In order to compare apples to apples and oranges to oranges, let's make a small comparison table which sums up all of our findings:

MP62:
675m3/hr - 145F increase - 54.6% efficiency
875m3/hr - 255F increase - 54.6% efficiency ASSUMED (and is quite lower in reality)

TVS:
675m3/hr - 111F increase - 73% efficiency taken from Eaton's map
875m3/hr - 205F increase - 71.4% efficiency calculated and coincides with Eaton's map

It is far from evident which supercharger is most efficient. However, spinning the TVS 1320 at 9000rpm is really not practical as it would require a large pulley and parasitic hp loss would be larger than that of the MP62 for the same airflow. So if someone wants boost levels below 9-10 psi, the TVS is not the right choice. Moreover, running any kind of forced induction device that produces 15psi of boost with no intercooling produces so much heat that detonantion can really become a problem.

On the other hand, the MP62 is at its limits when being spun over 18k rpm which as I and ronin have observed produces roughly 15psi. At that levels, the MP62 produces very large amounts of heat, its volumetric efficiency suffers greatly and parasitic hp loss goes sky high.

This means that the choice between these two superchargers really depends (once more) to power goals and engine setup...
 

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Discussion Starter · #12 ·
and you don't have no gears either and still you follow Phil's advice on updating just the gears where they clearly will not cut it!...time for a E153 upgrade....but wait that's stupid too .....cause Phil says so.
Well, used transmissions here cost about $450 and I pay no money for installation and dismantling. Until now (I am boosted for about 40k miles), this is the first transmission I break. If, say, I break my transmission every 10k miles (which is too often), after 100k miles I will have broken 10 transmissions with a total cost of $4500. Taking into account that I do about 5k miles per year, I need 20 years to do 100k miles and chances are that I won't be having this car anymore.

On the other hand, the E153 costs about $5195 and another $500 to ship. I guess you are intelligent enough to do the math. By the way, this topic is about the supercharger videos posted by Ryen, not about me, Phil or my broken gearbox...
 
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