rrrocketman

I'm creating a small series whereby I document my progress designing, installing, and testing my new electric turbo as a model for others who might be wondering whether the technology is viable or not. Enjoy

romandian

an electric motor will be able to speed up the compressor and reduce lag (look at garrett), but 10 kw is way to low to drive it. i have made the calculation once and (out of memory) came up with around 40 kw to drive the compressor on a ls1. i confirmed this number by looking at the rating of industrial blowers that provide similar flow.

rrrocketman

Can you show your math? I did a "compressor work" calculation years ago and found it takes considerably less than 10kW (about 13 HP) to produce positive manifold pressure in a mid-sized V6. I'd have to redo the calculation for the LS3 but I believe this motor is more than enough.

TurboLX

Funny, I decided to do some digging (it's been a while since I've had thermodynamics class) to gather the equations and unit conversions for the math. On an LS3 with a relatively serious amount of supercharged power, we would expect to see about 80#/min at 800hp, which probably requires a pressure ratio approaching 2.0 (14psi of "boost" beyond atmospheric). Assuming 20*C inlet temp at sea level and a compressor efficiency of 72%, I get 80.2kW required to drive the compressor. This is why you can't expect to drive a supercharger with a 4 rib belt without getting any slip. Transferring that much power from the crank to the blower pulley requires something like an 8 or 10 rib belt as seen in most kits today. This forum is rife with thread on belt slip if you don't believe me.

Pekka_Perkeles

Definitely will enjoy your progress!

rrrocketman

Even if that's true (the compressor work, not the claims about belt slip), the conditions are completely different from what I'm targeting on my car.

1) The volumetric flow rate required to feed the LS3 at redline (6600) and 100% VE is 722 CFM (http://4secondsflat.com/Carb_CFM_Calculator.html). Beyond that, we're in boost.
2) A 10kW motor can produce 3.8 psi of boost at the same redline load point (theoretical and after subtracting 20% losses, using the flow from 1) (https://www.engineeringtoolbox.com/h...ir-d_1363.html)

At lower RPMs the air requirement is of course lower, so we're talking a minimum of 3'ish PSI and it only goes up from there the lower in RPM you go.



Pekka: Thanks for the encouragement!

Chiselchst

Wow, eager to follow...I can't imagine the amount of work this entails!

One question (FAR from knowing anything), but wouldn't you want the blow off valve prior to the MAF?

rrrocketman

Normally yes because otherwise the MAF would measure the wrong air. However in my case I disabled my MAF because I'm running completely open loop. The only thing I need is the IAT sensor but unfortunately that is part of the MAF's wiring harness so I have to save the entire MAF just to get the IAT sensor. Since I don't need the MAF part though, I can stick it anywhere.

TurboLX

I mean this in the nicest possible way, but you are currently in way over your head. Best of luck in your current learning adventure.

rrrocketman

I'm not surprised you would say that. Same arrogant crap as in the other thread.

Kingtal0n

Electric compressor technology is on the horizon.

You can't get free power, and it does indeed take alot of electricity to drive a compressor to a high rpm and against a load.

That is why this technology is not 'stand-alone' but rather combined with traditional exhaust flow turbocharging.

The electrical power consumption component does not need to fulfill the maximum compressor rpm or load requirements;
it just needs to be able to 'kick start' the process until the exhaust flow can catch up.

This will only require around 20-40% as much power as would normally be expected to fully drive the unit.

rrrocketman

I don't disagree with that. Hybrid systems are quite good at what they do. However the power requirements of a blower are not so vast they can't be satisfied by an electric motor. Mechanical prime movers are quite a bit less efficient than electric motors which are typically greater than 90% efficient so it's not that hard to source a motor big enough to do the job.

playtoy

I ran an electric blower years ago. Hard part was carrying around 1320 feet of extension cord.

Just run a real turbo or supercharger. It will save you a lot of headache.

rrrocketman

I'm not in it for the convenience. If I were, I wouldn't have the right to call myself an enthusiast. Lots of cars come from the factory with everything I want in a car (or at least they did). I choose to buy a sub-par vehicle and put an untested piece of technology in it because it defies me and yet I know it can be done. I choose to do it in spite of the difficulty because success will be far more gratifying.

For your viewing pleasure

Just imagine where we'd be as a species if nobody attempted to do the impossible... and I'm only trying to do the difficult

Kingtal0n

The energy in exhaust gas is a superior source in any performance application over electricity and fuel. You can think of electricity like fuel because the cost is highly associated with usage.
turbines also provide cushion at TDC allowing higher engine rpm potential and safer connecting rod operation.

Every combustion engine from every manufacturer will always use a turbo if possible for any engine.

The advantage of electricity is that one can create a large amount of torque (and power) suddenly, by using it like a very potent form of fuel. It is quite expensive but quite limitless in possibility as well.

rrrocketman

I guess it depends on how you are judging the category. If you are looking at it from a cost-effectiveness point of view then yes, turbocharging is on top. It "recycles" otherwise wasted energy and has potent returns. I also agree that electricity is a potent "on-tap" energy source and it's that attribute of electricity that appeals to me. Not only is it satisfactory to get the job done but it can be controlled in a way that is unrivaled by other methods. Furthermore, whereas conventional boost methods are proportional to RPM, electrified boost is inversely proportional. When combined with a gas engine, electrification tends to compliment or synergize the torque response and produce a very flat and consistent curve that can be tuned arbitrarily to one's liking. Very handy for getting the absolute maximum yield from your hardware.

theandrewo

I love that you’re trying. Ignore the nay-sayers. No breakthrough technology has NOT had downers.
Will you succeed? TBD. But will you learn? Absolutely! Learning is a part of the process in creating new tech. Keep us updated, I can’t wait to see your progress!

rrrocketman

Actually doing this project has forced me to open textbooks that had been collecting dust up until now, spanning thermodynamics, fluid mechanics, electric machines, electronics and programming to name a few. No doubt failure has its benefits... but I don't plan on failing

Immediate goals are to finish my control algorithm, which involves taking half a dozen sensor inputs from the car and creating something like a truth table for when to boost and when not to and also to make a 2D table for handling motor duty vs battery voltage and RPM.

GX427

Keep going maybe you can produce this in the future and make it reliable. Would be cool if we could do this with a flip of a switch like nitrous and have instant boost by the Electric motor

old motorhead

Here ya go. Twin electric turbo's from my son's hero...