GM's eAssist...

[19bonestock88]

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?

[19bonestock88]

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...

[markweatherill]

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?

[t vago]

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...

[redpoint5]

Interesting, but why bother with such meager HP gains?

I can't see it improving MPG at all.

[Daox]

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:

[oil pan 4]

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.

[19bonestock88]

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...

[oil pan 4]

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.

[Randy]

Originally Posted by oil pan 4

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".

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).