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In the next few years all new cars will probably come equipped with stop/start systems: there's not much to it really and, except for increased wear and tear on alternator, starter and battery it's pretty well a freebie, efficiency-wise.
Proposed is a very basic start/stop retrofit kit:
- a couple
overpedals, one for gas, one for brake, fitting over existing pedals by say 0.5cm, which click when you step on or off of them. They tell the system when your foot steps onto or offof a pedal (regardless of whether the pedal is being pushed in) and give auditory and tactile feedback when the system has been engaged in some manner;
- a replacement crank pulley, the new one having a clutch to allow the accessories belt to turn freely when required;
- a small bit of electronic gimmickry to turn the alternator into a low-speed motor that turns the accessories belt when the engine is off;
- speakers to make vroom-vroom sounds and vibrations, for when the system is on but the engine isn't;
- a dashboard-mountable switch plate or box holding a bit of electronics and logic, for blinkenlights and an on/off switch.
- assorted wires and plugs.
Works on standard transmission vehicles, using the starter-motor at low speeds or bump-starting at high speeds, to restart the engine.
For automatic transmission'd cars it only works at a full-stop, to avoid weeping and gnashing of gear teeth. (All sorts of non-DIY stuff needs to be done in order to get a non-start/stop designed slush-box to do start/stop)
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Nearly everything except the engine would need to be replaced. The starter isn't adequate. The battery isn't adequate, the alternator would need to be a custom piece. The catylitic converter would need revision due to constant cool soak conditions, then after all of that, for what? Consumers are absolutely insane about off the line acceleration, adding a couple seconds to every car in a stop and go traffic situation is going to be a nightmare for getting people through intersections. |
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//adding a couple seconds to every car in a stop and
go traffic situation is going to be a nightmare// My
only comment is that I recently had a new Jag as a
courtesy car, with stop/start. There was no
appreciable delay; the engine restarts as you take
your foot off the brake, and is ready by the time
you've reached the accelerator pedal. |
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I've heard good things about the Ford system. I'm more excited about the mazda fire start system which promises to be awesome. As a tinkerer in such things I made a quick list of the problems that I could see. To add this to an existing cars with automatic transmissions could be as simple as adding a gell mat battery and a far better starter, then maybe a power steering pressure reservoir and vacuum reservoir to deal with some issues with drivers freaking out. |
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//nearly everything would have to be replaced// |
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This was envisioned as a name-brand quality kit, of the S/S specific components which can't be sourced from an auto-parts store. |
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There's plenty of aftermarket performance gear which requires or seriously suggests an upgrade of other components. |
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Firstly let's note that failure/wear on the starter-motor, battery, alternator aren't safety issues. |
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//battery// There's a couple YT vids (unrelated to SS) concerning a guy who completely replaced his battery with a small supercap bank. Supercaps don't degrade from use and it took the stock alternator less than 3 seconds to completely recharge the bank after a cold start depletion. I'm not suggesting tossing the battery, just adding the supercap bank to completely shield the battery from wear and tear. |
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//alternator// I don't think there's any mechanical reason why an alternator can't be run in the same direction it does when used to produce electricity. The energy required in this case is just enough to run the power-steering and brakes' pumps at minimal speeds, probably less than idling. Some soldering required to patch in the motor circuitry. A more powerful replacement alternator suggested but in the meantime the A/C may have to be turned off (automatically) during the stop cycle. |
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//starter-motor// My 17 year old truck takes 2 seconds to cold start and less than half a second to warm-start. It's a given that a more powerful starter will decrease the starting time but half a second is certainly good enough for leisurely driving. |
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//catalytic converter// I didn't consider that... so how do existing start/stop systems handle it ? |
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//Consumers... insane// If you're an insane consumer please don't purchase my product. And what [MB] said. Though I will note that I drove a vehicle (automatic transmission) with stop/start and the lag was noticeable, so they're not all created equal. |
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//nightmare// so reach over and turn the system off if it's being thrashed. No biggie. |
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Among the things I didn't put in the post for brevity's sake: |
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- sensor for the engine turning over to avoid grinding the starter gears |
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- switchbox contains all sorts of neat stuff like slow cold-starting to lube the engine up before starting it, A/C interlock, etc., provision for "crawl mode" where the starter motor is moving the car (good for queues and driveway-only maneuvering) |
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- logic includes plenty of safety features. F'rinstance the system reverts to "Off" when the key is removed: you have to turn it on manually after you start the car for the first time. System disengages in case of alternator or starter fault, or speakers disconnect. System suspends operation in low battery condition. Engine offs are delayed by say 1/3 second to keep the engine running in case of sharp maneuevering (gas>brake>gas really quick). Etc. |
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Note that, unlike existing SS systems this works at speed as well as when fully stopped, allowing for gas-saving coasting. But only for standard transmission and it's a given that your clutch leg might get tired if you take advantage of every single occasion to coast with the engine off. |
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//firestart system// yeah that's cool but I don't see how it could be retrofitted to anything. |
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//gel mat// After watching a YT video (as noted in the previous anno) I'm thinking a tiny supercap bank which could hold a couple of starts worth and say 30 seconds of engine-off power requirements so maybe 0.01kWh whatever that translates into in farads, to supplement the existing battery. |
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For automatic transmissions, having done a bit of half-research, start/stop is easily doable at a full-stop scenario (the car stops completely, then engine is turned off, the car is started, the car continues onwards, all while remaining in gear). |
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For any other scenarios (eg: coasting to a stoplight) it won't work properly without quite a bit of hacking. The problem is that slushbox gear-shifting is powered by a pump which is powered by the engine turning over. So when the engine's turned off it will remain in whatever gear it's in. Then you'd have to wait while the pump energized and the tranny changes gears to whatever the new one is. And in the meantime there's hydro-clutch braking since it isn't in Neutral. |
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//[expanded ps, pb pressure reservoirs]// |
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That sounds like a good idea to compete against electric ps and pb. |
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For a retrofit, hmm... it'd be more expensive than the $5 worth of diodes required to turn the alternator into a motor, but it'd also be much more efficient and the clutch crank-pulley wouldn't be needed. Sign me up. |
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