belt-assist engine RPM spinup.. worthwhile? - PeachParts Mercedes-Benz Forum

patbob · #1 05-12-2010, 05:34 PM

While reading one of my magazines on a plane recently, I ran across mention of a type of "hybrid" vehicle called Belt-Alternator-Starter (BAS). While BAs is a useless concept for my old diesel, it got me to thinking and doing some further reading.

Would there be any value to adding a motor to help spin the engine RPMs up from idle and get it into a different part of the power band for take off from a dead stop? Any guesses as to how big of a motor would be needed?

Here's a few links fo those that want to know more about BAS:
http://www.underhoodservice.com/Article/62180/Power_Assi.aspx

http://green.autoblog.com/2009/04/30/greenlings-what-is-a-mild-hybrid/

http://ezinearticles.com/?Belt-Alternator-Starter-Hybrid-Systems-Are-No-Longer-a-Dream&id=1595026

Elsewhere, you can find info on converting automotive alternators to 3-phase AC motors. A 130Amp alternator is approximately a 2HP motor and the one from the Saab is a conveniently available junkyard part that's also a bolt-in replacement. Would a measely 2HP be enough to make a difference?

pawoSD · #2 05-12-2010, 05:53 PM

2HP would do nothing. Now, if you added a motor that could pump maybe 25-30hp into the system, then you'd have something. But you'd need a significant power buffer/supply like a capacitor bank or batteries.

jt20 · #3 05-12-2010, 06:03 PM

if you have an automatic transmission, this is already accomplished by the torque converter.

patbob · #4 05-12-2010, 08:04 PM

The torque converter converts kinetic rotational energy into torque, It also acts as a buffer to bleed off excess rotational kinitic energy (as heat). It doesn't help the engine spin up in RPMs when you press on the accelerator, although it does allow it to do so.

Adding a big enough motor would help spin the engine faster, not just allow it to do so. I'm actually counting on the torque converter because without it, the motor has to be big enough to push the entire car so the wheels can spin faster.

layback40 · #5 05-12-2010, 08:37 PM

BAS was used on the very first Suzuki 4wd. The 360 I think they called it. It was a 360cc 2stroke. As soon as they went to larger motors, they needed conventional starters.
An 80 amp alt would be approximately equivalent to a 1kw motor if one was able to reverse its use, this is not possible with its existing design.