Idea ive had for a wile.... Options

[mandrek]

So here it goes, i have a 95 ST (7afe). that i DD and do auto-x with. i have been looking at doing a few mods to help with reducing paracitic drag off of the week 7A motor, and have come up with a few ideas that i would like to run by u all.

i have read a number of threads on hondas taking the MR2 EPS pump and running the set up as to remove parasitic drag off the motor. now, here is what i have been thinking of doing for a wile now, it should be a pretty simple set-up, but am looking into getting some info on the topic before i make the plung..

currently the PS and the water pumps share a belt on the 7A.

what i have thinking abut doing is adding a small electric motor to that side of the motor and remove those two pumps from pulling off the crank. sorta like this.

E-motor
(o)\
|----\
|-----\
(o)_(o)
^----^
PS-----water

not only would this remove 2 sorces of paracitic drag from the crank, but it would also avoid the water-pump from developing cavitation at high engine RPM's AND allow for the PS to be at full boost almost all the time..

the car is still not a dedecated track car so the on/off full PS boost may not be compleatly nesisary, but still an advantage wile auto-xing.

let me know what u all think.. looking for ALL input good or bad..

This post has been edited by mandrek: Mar 25, 2010 - 7:49 PM

[rave2n]

So the question is, place to mount, bigger belt, and make sure the motor your using to run, isn't dragging the alt/bat to much....

[mandrek]

So the question is, place to mount, bigger belt, and make sure the motor your using to run, isn't dragging the alt/bat to much....

indeed. belt should not be a problem to find, just got to get a rough measurment and then let the adjustment on the mount (like the alternator mount) to pull out the slack and ++ the tention on the belt..
the motor is definatly a concern but i have not looked into it just yet in hopes of finding one that is already in use by a racing teem.. or somthing of that nature.. perhaps i wll have to change the alternator to that of a 3rd gen 3s (higher amprage if i recall) and was thinking of supporting the system with a 1/2f cap.

[Ruroniarc]

I'd like to preface this statement with the fact that I am an Electrical and Computer Engineer from Worcester Polytechnic Institute. I do have some actual knowledge pertaining to what I'm talking about here, I'm not just making assumptions.

That being said, if you remove the belt that powers those two things, and move it to an electric motor, the electric motor will be pulling energy from your battery. In turn, your batter will be pulling energy from your motor through the alternator. Factor in the losses / efficiencies of the electric motor (Electric motors usually have no more than 85-90% efficiency). Then factor in the efficiency of your alternator producing power (which is just an electric motor run backwards (so, again, another 10% loss). Then factor in the weight of the new mount and electric motor (not much, but it's still there).

Therefore, you're already looking at (minimum) 25% efficiency loss.

There is a reason every car manufacturer powers their water pump and other accessories from the engine directly, because there is a 0 percent loss there. Instead of going from the engine to the pump |--|, you're trying to go from the engine, to the alternator, to the battery, from the battery, to the electric motor, to the pump |------|.

[mandrek]

I'd like to preface this statement with the fact that I am an Electrical and Computer Engineer from Worcester Polytechnic Institute. I do have some actual knowledge pertaining to what I'm talking about here, I'm not just making assumptions.

That being said, if you remove the belt that powers those two things, and move it to an electric motor, the electric motor will be pulling energy from your battery. In turn, your batter will be pulling energy from your motor through the alternator. Factor in the losses / efficiencies of the electric motor (Electric motors usually have no more than 85-90% efficiency). Then factor in the efficiency of your alternator producing power (which is just an electric motor run backwards (so, again, another 10% loss). Then factor in the weight of the new mount and electric motor (not much, but it's still there).

Therefore, you're already looking at (minimum) 25% efficiency loss.

There is a reason every car manufacturer powers their water pump and other accessories from the engine directly, because there is a 0 percent loss there. Instead of going from the engine to the pump |--|, you're trying to go from the engine, to the alternator, to the battery, from the battery, to the electric motor, to the pump |------|.

i had thought about that my self but was unsure as to what the exact numbers were (though i never went into a career with it, i did do 3 years od Electronics in high school and was deep into micro-precessors and such as one of my last study units,{about 8 years ago}) my assumtion was that the load the electric motor would draw from the system would be far less than what the alternator would be puting out. there are a number of OEM examples with the PS-Pump is run off of an electric motor, as well as water pumps being driven by electric motors for race aplications, (were the need for efficiancy is greatest) but i have yet to see both done at the same time, the idea was that since the two pumps sit side by side and would only require a bracket and an electric motor (and the room is there) than it might be worth a try.. damn it i hate crunching numbers..

[Mstoochn]

or you could just remove the PS pump...

[Ruroniarc]

You could still try it, but it would be for a track car, because the way it would work is the motor would draw off the battery until the battery got low, then the alternator would drag on your engine. So you would get this magical boost for a while, but then it would just go away once the alternator started pulling more.

[mandrek]

You could still try it, but it would be for a track car, because the way it would work is the motor would draw off the battery until the battery got low, then the alternator would drag on your engine. So you would get this magical boost for a while, but then it would just go away once the alternator started pulling more.

ok well ill do some more poking around and get my numbers lined up b4 i go any farther... im just hopeing that i can find an electric motor whose draw will be far less than what the alternator will put out (even if i have to rewind/upgrade the alternator) im still basing this on the principal that 75% of the time the PS and water pumps operate at too high a speed to be optimal for water flow/ pump preasure... so in fact may just need small motor to do the trick.

OR i could do what most auto-x guys are doing, and instead of driving the pump pully with a small motor, i could just get a genII MR2 electro-hydrolic PS pump (ware the motor is built in and is the actual pump vs being a piggyback unit) and just leave the the water pump and the alternator to be mechanicly driven by the engine... was realy looking for a way to get the water pump off the belt as well, but gurss not.... baby steps! alot more research to go!.

[rave2n]

You will need to upgrade your alt, that is a must.

Umm, side note. 25% eff. loss on the electric motor starting, thats incorrect. Its much less, still viable to look though.

"There is a reason every car manufacturer powers their water pump and other accessories from the engine directly, because there is a 0 percent loss there"

This statement is also quite false. They go with a pulley type system because its cheaper, not because its a bad idea. Its also easier, and a standard that has been used in cars for a long time. Most mechanics are not electrically inclined persay. Saying that there is 0 percent loss from powering the pump and such ..... I think common sense will enlighten that one, I don't need to expand further.

This is a completely viable option, if you have the time to fabricate, and do the MATH correctly. You can make up for the strain on the electrical system. You also need to factor in any mods that you've put on the engine that increase its eff. Also remember to adjust for this change, as your engine runs according to spec, taking this much strain off of it, I can only assume would need adjusting.

I'm also no making assumptions, but I also don't need to title drop to prove my point. I've brainstormed this with many intelligent minds, and it can be done....efficiently. Not to mention...its already being done.

This post has been edited by rave2n: Mar 30, 2010 - 12:53 PM

[delusionz]

This argument rings familiar with every time an "Electric Supercharger/Turbo" conversation pops up.

To use electricity to make power (or save power) you need to get the power from the alternator,

Just hypothetically, Say if your alternator is loaded up by a device drawing 1kW (1000 watts) then it may rob the engine of how much? 1.25kW ?? Maybe more?? + Many other factors which add sacrifices.

Perhaps consider why superchargers run on a belt with the crank, and why RWD cars with N-S mounted engines have their radiator fan on the crank instead of using an electric fan.

Since we have an electrical engineer in this thread, he may touch on the subject of large capacitors and battery technologies, but then we would just be breaking the tip of the iceberg of what hybrid vehicle engineers have been trying to master for years.

I'm sure if there was a quick easy way to make more power than the sacrifice it would make, it would already be in the forum stickies yeah?


So in short, electric motors are more efficient than petrol engines, but you still need that petrol engine to create the electricity in the first place.


I'd really love for someone to come and disagree with me though, this is a very interesting topic of conversation.