GM's eAssist...
 

So, I read about one of GM's hybrid systems and it looks easy to implement... They have an electric motor attached to its serpentine belt system, which provides additional power to supplement the output of the gas engine under high load conditions... Such system was briefly used in Buick models for a mild boost in fuel economy...

Now, if my L61 never had an A/C compressor, it would be as simple as getting a belt for A/C and mounting the motor in the A/C location, but since I'm not ditching my functional A/C, I'll have to go a different route, using LSJ tensioner, alternator, and idler pulley assemblies, and mounting the motor roughly where the supercharger snout would be on a Cobalt SS(or my Ion Redline)...

The key is finding a motor potent and small enough to fit... Opinions?

After some more research, the GM system replaced the alternator with a generator/motor... Given that it goes onto the 2.4 liter engine, there's a chance it would bolt in place of my alternator, but it is fairly expensive and chances are, I would need to figure out the GM electronics to get it to charge my 12V battery, and it's own 115V battery... seems easier to add a motor than to replace my alternator with the GM eAssist one...

Does the eAssist version have a special belt?

I'm sure that adding a motor to a regular belt drive would involve putting the belt under significant tension to transfer the power. How about a toothed belt?

Very intriguing idea.

Seems to me that, under this eAssist, the prime mover would briefly become the generator/alternator, with the engine itself briefly turning into an accessory.

As long as the belt was routed properly, and as long as loads did not exceed 5 HP or so, there should be no need for a special serpentine belt.

I could see this being used to move a vehicle from a dead stop condition. Not sure about WOT performance, though...

Interesting, but why bother with such meager HP gains?

I can't see it improving MPG at all.

Going to have to agree with the above. Too much hassle for too little benefit.

Brucey did a similar mod on his Subaru Outback years ago. His mileage benefit was quite real, but in the end not worth the effort he said. He parted out the system about a year later.

More info here:

http://ecomodder.com/forum/showthrea...ack-13932.html

And a few pics:

http://ecomodder.com/forum/attachmen...1&d=1280174081

http://ecomodder.com/forum/attachmen...1&d=1280989429

http://ecomodder.com/forum/attachmen...1&d=1311103164

The problem with eAssist is it didn't work.
It got worse fuel economy on the highway and about the same in the city.
This hybrid idea is from back when GM thought it was more important for a vehicle to have a badge that says "hybrid" then to build a "hybrid" system that actually worked.
This hybrid system reminds me of when GM used put an air pump on vehicles to blow air into a vehicles exhaust stream to "reduce emissions". It works on paper, but in the grand scheme of things in the real world it don't.

The regular drivebelt can support the levels of power provided by the electric motor; consider that the Cobalt SS supercharged, when modded and generating 300whp with the stock blower, the blower is contributing losses of 25-30hp by being so massively overspun(2.7" pulley), and no belt slip with proper tensioner and belt length... Adding a similar amount with an electric motor is surely possible...

I found a small diameter motor that is rated at 4hp@13.6V, but mounting it would be a challenge, maybe weld brackets to the valve cover? I don't want to get the eAssist alternator, not wanting to figure out its complicated logic to not only charge the cars battery but also assist the engines output at high demand, low RPM situations... Basically, I would use the motor when climbing hills to keep the transmission from downshifting(or even to avoid adding throttle at all), and maybe to help when taking off...

But, ROI would be horrendous, all considered...

I was running some supercharger calculations for diesel place for a guy using a super charger. He was putting about 40 horsepower through a 6 rib serp belt.

The valve cover is not a load bearing structure unless you have fabricated valve cover. If they are die cast aluminum then there is little chance anyone will be able to weld anything to it and not have it crack immediately.

I'm still amazed people think that was a scam somehow. Before computer-optimized designs, engines ran rich sometimes. They could still control emissions by injecting air into the exhaust before the catalyst. That's because cats reduce pollutants easily 100:1, but only in a narrow mixture range. Emissions standards have always been per-mile and lab-grade emissions testers add air for constant volume, so extra air out the tailpipe can't even be measured, let alone game the test. It wasn't limited to GM or Ford: I had a '85 Honda Accord with a reed valve exhaust-air system (even with CVCC).

GM has had a belt assist system for a while. I think it's mainly for the hybrid badge. The problem with running through a belt is that belts will slip with torque, but don't care about speed. Electric motors can have a lot of torque, but have a low power limit. These don't mesh well. You can feel a 10 HP electric motor on the flywheel or transmission because it's instant and the engine isn't making much power at low RPM. By the time/RPM a belt can handle that, the engine is up on power and the increase is like a 10 HP nitrous shot (i.e. not worth the trouble).

This hybrid system could work, but not just as a bolt-on for people on this site.

Most hybrids' main benefit is from downsizing the engine close to the minimum required for cruising (or running Atkinson cycle) while maintaining reasonable power on reserve for passing. Simply bolting on an electric motor will not do this. However, electric assist could, for the average driver, prevent some degree of downshifting, or allow for lower gearing with the same drivability. Although I imagine most on this site would give up a bit of rate of acceleration for more economy, everyone has their limits, and that extra bit of torque could make "excessively" tall gearing more bearable.

On my Insight, electric assist makes available around 30% more torque in the rev-range I typically run. Because of this, I can keep up with traffic with the little 1L engine without ever revving over 2000rpm. It produces as much or more torque than Honda's 1.6-1.8L engines at these low RPMs.

http://www.insightcentral.net/_images/enperformance.jpg

http://www.cars.com/crp/vp/images/06...rve_hybrid.jpg


The next biggest benefit is auto-stop, which many of us here do already with kill switches or key-off, but a hybrid system makes it a lot less trouble to use. In my Insight, I shift into neutral and tap a button, and the engine dies. When I'm ready for the engine to come back on, I tap that button again or throw it into gear and it springs to life silently, without putting any wear on a starter motor or clutch. I can't stress how luxurious it is for the engine to auto-stop at a redlight or when rolling down a hill and start itself back up without the need of reaching for the key or bump-starting it. More than any other feature, I'd miss this one the most if I ever went back to a non-hybrid gasoline vehicle.

Regenerative braking probably doesn't account for all that much in terms of economy for most of us here, but would for a more typical driver. For me, the biggest benefit is that I can go longer on a set of brake pads - I swapped out my factory pads just past 200k and they still had plenty of life in them.

Some smaller benefits: Most hybrid systems can more efficiently produce 12v than an alternator, even with a DC-DC converter, and for non-belt hybrids, get rid of some parasitic losses from belts, so you have close to the same benefits as an alternator delete without actually giving up your ability to charge the 12v battery.

This sounds familiar...
SpeedStart

Even though eAssist doesn't provide full-hybrid capability, it's still a reasonable improvement that could have been more widespread nowadays.

I bought a '13 LaCrosse eAssist a week ago, and had my first fillup this morning. 30.88 overall, slightly above the EPA combined rating of 29. I'm noticing that this car is a real gem on the highway - I could probably beat the 36 EPA highway rating on a long trip. However, the weight makes acceleration a FE killer. With me and some gas, it's over 4100 pounds. When accelerating from a stop or at low speeds, the onboard instant FE readout can easily slip to the single digits unless I'm mindful of what I'm doing.

What if the system was plug-in? seems like an electric motor that came on out of corners on a twisty road or high speed freeway driving would save some gas.

Since it's not exactly meant to be a full-hybrid, actually more related to a KERS, I'm not so sure if a plug-in setup would provide so much of an improvement on mileage.

I'm actually doing some analysis to answer this question. I'm in the middle of it, but the results so far suggest an increase of 22->31 mpg E85 or 26->37 depending on route. I thought I had the mpg calculation calibrated well enough, but the second dataset did not correlate with my measured average as well as the first one did, so I'll have to figure that out.

The two main parameters I'm looking at are the decrease in map when the electric motor is engaged, and the decrease in gas motor rpms that is possible due to deceased power demand.

I'm more interested in plug-in because I do about half corners and hills and half flat and fast in my commute. I hardly use the brakes, but there is a fair amount of compression braking. I haven't yet figured anything to model the potential for regen, but I think it's pretty minimal in this application.

With limited regen, a plug-in could be the solution. My LaCrosse seems to go into regen mode every time my foot leaves the accelerator, unless I coast in neutral. The touch screen and DIC both have an optional display that shows current flow - toward the wheels when the generator's engaged, and toward the batteries in regen. My DIC looks like this one; touchscreen is larger:

http://st.motortrend.com/uploads/sit...nt-cluster.jpg

I see the biggest benefit of the eAssist system on the highway, where it keeps me in TC lockup. I can both hear and feel (slightly) the generator kick in at speed.

I'm sure it helps at lower speed, as well, but that car is so heavy and takes quite a bit of effort to motivate it from a dead stop. The DIC instant mpg readout is dismal in those circumstances, but it would probably be a fair bit worse without the eAssist.

Thanks for the pic. I figured it would go into regen when you take the foot off the gas, but it seems like the energy you can recover is very hampered by the compression braking. I'm thinking of my civic, it probably helps more in the heavier buick. I think the variable valve timing could be used to help with your car as well to relieve some of the compression. Does your display say what the regen power is?

No specific indication of power amounts - the battery icon on the right has six segments showing how much of the total battery capacity is available, and that's it.

I suspect you're right that the weight of the Buick helps overcome some of the forces of compression braking. Much of my commute has enough traffic to minimize the benefits of coasting in neutral, so I get a fair amount of regen.

I was looking at buying a high mile 2013 Malibu eco with e-assist for $1500 with broken ac.

From what I can tell you can’t reasonably keep the ac working in these cars, the hybrid batteries are always failing and there are recalls for fire risk to contend with.

Even though the car runs fine without the hybrid battery once it fails the 12v stops charging.(sound familiar) and no one has come up with a way to bypass

I really would like to get it for an injured relative to use as a winter beater (body is rust free, just high miles) but it’s just too risky to try and keep one of these running and on the road

NB that sometimes the engine is turning the alternator/motor
and sometimes the motor/alternator is turning the engine.
That means that 1st one side, then the other of the belt will be the slack side.
So you need 2 spring loaded tensioner pullies or it will slip in one direction or the other.

If you look at the crankshaft pulley, is there enough space in front of it to mount a high, car matching, rpm motor?
That saves on belt and extra tensioner pulley losses and no 'is the belt strong enough?'

There's lot's of talk here of "...only 2/4/etc HP...not worth it..."
It's all ill informed nonsense IMHO:
Everyone is relating that HP to the torque of a similarly powered engine.
That is NOT! the case!

There are hotrodded (cooled and overvolted) E-bike motors pushing MORE TORQUE THAN A 1300cc CAR for short ~10 second bursts. (Acceleration is short bursts)
And they do it from zero RPM where an engine cant sharpen a pencil.
ie: The two power types compliment each other beautifully.

A crank or belt mounted motor will have the torque multiplication of the gearbox too, just like the engine, so doesn't need to be large.

How do you plan to control the motor??

Late to reply, but a bypass to get the 12v charging again should be relatively easy. The altermotor will have 3 phase lines between it and the motor drive unit, which rectifies it to DC and connects to the battery, which then connects to a DC-DC converter.

I have verified all Honda DC-DCs just turn on and work once they start receiving power, whether it's a 2000 or a 2015. If 12v isn't charging, it's because a relay has disconnected HV from the DC-DC. You can either bypass/short the relay, or just connect the high voltage lines straight from the motor drive to the DC-DC.

If for whatever reason GM's DC-DC required an ECU to turn it on, and it's inactive until that happens, there are aftermarket units available in whatever voltage and current range you want, starting around $100, and you simply connect them to the output of the drive unit.