P2 Supercharger Thread

Can't wait to continue my test too 😂 last year was good for me. All of this feels like a "race" between us! Who's going to find the most reliable set Up! I like it! We have 2 set up that have been in a car. Same project but different conception and parts!
 
Take a look at www.pmas-maf.com and www.njkprecision.com if you'd like to get a NIST certified result for airflow when you're ready, I'd be happy to help. We do OEM automotive development, aftermarket automotive, as well as scientific instruments. I'd be happy to assist you with metering MAF instead of relying on the pressure gauge. MAF will tell us exactly how much power can be supported dependent on fuel of course.
 
@AlexLTDLX if you'd like to discuss this over the phone, please PM me. I'd be happy to work with you on a calibrated sensor and tube that you can easily integrate into your data acquisition to meter air volume.
 
Also, if your ESC will accept a 0-5v or pwm input which I assume it does, it'd be fun to use a Dial-A-Boost or similar to target MAF or pressure.

Very cool project, congratulations on your progress. There is some cool use cases for index class racing here for sure.
 
WB projects said:
Can't wait to continue my test too 😂 last year was good for me. All of this feels like a "race" between us! Who's going to find the most reliable set Up! I like it! We have 2 set up that have been in a car. Same project but different conception and parts!
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i dont think they are comparable personally .. you are doing a system for small capacity engines.. While Alex is doing something for much larger engines... It's doubtful many if anyone with a small engine will use this p2 charger... So i think both can co exist
 
"comparable" I mean.. how do we drive the impeller, what ESC is the best, what battery is the best. Is comparable in the way we all work with the same stuff, just for different application. Like you said I will never put the p2 in my car and we need to co exist for the documentation we can all relate
 
I'd rather turn a larger charger at less load for a smaller displacement provided it's within it's efficiency range than drive a smaller inducer harder, but ultimately data will decide if that's a good decision or not. This is exactly why I would like to connect up with some of you in order to do some flow analysis.
 
Remember that at least in this instance sizing of compressor is going to be very different than exhaust driven setups. There will of course be diminishing returns, however less load on a larger compressor driven by electric but flowing similar air to a smaller compressor housing that is going to require more current to provide the same air volume because of compressor efficiency maps is going to be something to consider.
 
BenchworxGarage said:
Remember that at least in this instance sizing of compressor is going to be very different than exhaust driven setups. There will of course be diminishing returns, however less load on a larger compressor driven by electric but flowing similar air to a smaller compressor housing that is going to require more current to provide the same air volume because of compressor efficiency maps is going to be something to consider.
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i think your missing the point...

Bigger engines need more Air flow than a smaller engine.. Big engines the P2 will suite but for a small engine it wont.. This is not about a small one driven hard V a big one driven slowly... It's about the right size blower for your engine.

For example WB projects has a 2L engine and i have a 1.6L where as alex has a 5.5L i believe

The other point is that p2 is physically large so that can be a problem in the small cars.

This forum will not result in a one size fits all option thats ideal for all engines. It will result in a number of options with all having merits.
 
MkngStffAwesome said:
i think your missing the point...

Bigger engines need more Air flow than a smaller engine.. Big engines the P2 will suite but for a small engine it wont.. This is not about a small one driven hard V a big one driven slowly... It's about the right size blower for your engine.

For example WB projects has a 2L engine and i have a 1.6L where as alex has a 5.5L i believe

The other point is that p2 is physically large so that can be a problem in the small cars.

This forum will not result in a one size fits all option thats ideal for all engines. It will result in a number of options with all having merits.
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You didn't look at either of the previous URL links that I posted did you? I perfectly understand airflow, that's my job. OEM automotive, aftermarket automotive, and lab grade equipment with the only NIST certified flow stand in the country capable of moving enough airflow to surpass a ProMod. I understand entirely what I said, and I meant what I said. If it's a discussion that you'd like to have backed up by some data, which seems to be of importance here thank goodness, I'd be happy to have it tomorrow. Have a wonderful evening my friend.
 
I can make a smaller compressor housing move less but resulting in higher pressure because of inefficiencies and heat. Stop making assumptions based upon volumetric efficiency and manifold absolute pressure and start measuring the actual mass air flow. I was under the assumption that this project was an effort to provide data and prove viability, if that is indeed your goal then data proving metered air is a no brainer.
 
Sorry I don't know how to take your message but it look like you are a little bit irritated. I'm a french guy so it's sometimes hard to fully understand/explain points for me. Yeah the idea to have data look cool but it have more then this in the process. We allready prove the viability of the project. But in my case, bench test is just a good way to know where to start with the ESC and motor settings. I will work with an allcherry sensor to make my boost by RPM. Because right now I can't just full throttle on all the RPM. When I would want number of the gains, I will go see my tunning datalog.
When I say I need pressure and not airflow. Tell me if I'm wrong but, how can I get more power with less boost? I can't push more air but I can compress it? What did I don't understand of your reply?
 
WB projects said:
Sorry I don't know how to take your message but it look like you are a little bit irritated. I'm a french guy so it's sometimes hard to fully understand/explain points for me. Yeah the idea to have data look cool but it have more then this in the process. We allready prove the viability of the project. But in my case, bench test is just a good way to know where to start with the ESC and motor settings. I will work with an allcherry sensor to make my boost by RPM. Because right now I can't just full throttle on all the RPM. When I would want number of the gains, I will go see my tunning datalog.
When I say I need pressure and not airflow. Tell me if I'm wrong but, how can I get more power with less boost? I can't push more air but I can compress it? What did I don't understand of your reply?
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My apologies if I seemed irritated, my friend. I'm trying to explain that pressure is not the same as air mass. I can make equivalent air mass a higher pressure within a given container by increasing temperature, correct? Compressors create heat in a multitude of ways.

What I am trying to explain is that looking at the efficiency maps of any given compressor housing and inducer wheel to find what is best suited for your given air mass target and working backwards from there is going to reduce inefficiencies both in the compressor as well as the load on the electric motor. I'm sure that you can spin a smaller charger fast enough to supply your desired airflow, but if it creates a bunch of heat that increases pressure at the expense of density along with increased load on the electrical system it is going to be far less efficient than finding a compressor side that is efficient for your desired air flow and reduces load on your electrical system.
 
I think we're all on the same page here, just wires getting crossed. WB's setup (so far) is the only other one that's actually been mounted on a car. Of course the power levels are different, but the concept is the same. He's a good guy; as is everyone on here so far. Making Stuff Awesome has contributed a lot too; especially in regards to the arduino code. And BenchworxGarage - welcome!

In any event, I do appreciate your offer, but I'm not one for endless bench testing. I just wanted to dial the VESC in, bolt the thing to the car and drive up to the dyno. And tonight I finished dialing the VESC in. I'm having somewhat mixed feelings at this moment, so I don't really want to get into too much detail, but at least know the P2 unit held together just fine (and terrifyingly so) at over 30,000 impeller RPM. Then we loaded it harder (ran it wide open into choke), and it wasn't able to break 20,000 impeller RPM, but I did see 400 amps motor current. I need to parse the data (and edit the video) before I come to any rash conclusions.
 
cmoalem - You were right. I was wrong. That's my conclusion after thinking on my results last night. I'm talking about the pulley ratio thing - you went with a few options - either 1:1 or less (motor spinning faster than impeller), I went the other way (motor spinning slower than impeller).

Here's what I learned. At some point, total power needs to go up. I was wrong because I was thinking more in linear terms as opposed to duty cycle terms. Keeping the motor slower and hoping for more torque doesn't work in brushless motor world. Here's why: rpm is based on voltage; voltage in an ESC is based on duty cycle (voltage is averaged between "on" and "off" pulses). When you're running at 50% duty cycle at 50 volts, the motor sees an average of 25 volts. At 50% duty cycle, even though the current pulses delivered to the motor phases are double what battery (i.e. input) amps are; average voltage is half. If you could hit 100% duty cycle (you can't, because you need time for commutation to occur), then battery current would equal phase current, and average voltage would be battery voltage, giving you the most system power (in watts) possible.

But at lower motor speeds, total system power suffers. And we want to put as much energy into the system as possible to maximize impeller speed.

On the bright side, I was able to hit 400 motor amps with a completely flat (i.e. no spikes) current line with these monster batteries. Now I just need to get duty cycle up by spinning the motor faster (smaller motor pulley - maybe a 14, 15 or 16 tooth pulley; and that will necessitate a shorter belt - basically what cmoalem bought in the first place). Then we can really try to optimize things. The "tuneability" factor of this setup is what's really awesome.

Here's a look at 400 motor amps:
vlcsnap-2022-02-10-02h59m41s217.jpg
 
Thanks @AlexLTDLX !

at times I feel bad because my contributions here so far are "behind schedule" and more on the theoretical side.

But until now you are the man going through most of the practical "experiments", development cycles (and pitfalls) and sharing your valuable findings here so we followers "do not take the same turns". THANKS a ton!

I hope work load allows me to "get to hands on" soon. I will happily "give back" here on the forum.
 
LOL - We're all "behind schedule." My MGM/LMT setup got hung up in customs because they included a T shirt, and they have strict customs stuff on clothing. Silly.

I have to tell you, when running the thing at 30,000 impeller rpm inside the garage, it's terrifying. I put up a sound pressure meter and 5 feet away it was still 109 db. Of course, once I removed the restriction and ran it into choke (much lower rpm - in that screenshot, we were only at 17,500 impeller rpm. It seemed so much safer at that speed.

The nice thing is that we know the TP Power motor doesn't melt when getting hit with 400 amps (the most we pushed through it before was 280; though at a higher duty cycle), the belt seems to hold up fine with no need for an idler, and the LTO packs are amazing. In fact, in all this testing (both videos, over a span of a week with testing in between), I haven't charged them yet.

I just wish the T5 belts and pullies weren't so hard to get a hold of.
 
Somewhere we were having the discussion about Efficiency and gearing. I was inspired to investigate that.. To be honest there is little info about it.
However it seems that a highly Loaded motor which would be a slow motor turning the Impeller faster would be Far less efficient that the opposite.

The reason for not suggesting high motor speed relative to the impeller speed is that the more powerful the motor is will mean that the motor is larger and therefore unable to spin fast enough.


Also on efficiency. Having 50v at 50% duty cycle is less efficient than 25v at 100% duty. There is good info on that one.
 
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