Intake mods, alternator load, etc.

[1.2gees]

I just got done reading "Bmw Enthusiast's Companion" (great book borrowed from a friend), and there was an idea that stuck out...
Wiring in (a relay would be my route I presume) a switch so you can disconnect the alternator (or rather the electrical load on it) so it takes much less power to turn it, when needed. It's indicated that this difference wouldn't be that great, but supposedly it's there. What is a relistic amount to be gained from this 'modification'? I would probably wire it into my throttle switch, with nothing in the cockpit, if I think it's worth the trouble (alternator cut off at full throttle, back on at every other throttle position). Ideas?

Also, I need a battery. With the above mentioned about the alternator, I think a yellow top optima would suit my needs, suggestions?

Also, I just purchased a throttle body/intake manifold, and I'm planning to bore both of them, port matching the intake to the heads. According to certain advertisers (I know better than to take their claims too seriously) the bored out throttle body alone will provide 10+hp... I don't expect that, but I acquired both for $25, and I know I can sell mine that are installed on the car for more than that, do you guys think this is a possible source of additional power? Opinions?
Thanks.
Ahmet

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It's all the driver...
My page over1g@hotmail.com
Porsche owners Gallery.../My 944

[mideastmafia]

im thinking of having some kind of chip that will monitor the voltage the car is getting and once its beyond a certain number, to turn the alternator back on. i think it would be better if you had an alternator that had some form of clutch device (ac compressor) that would let it spin freely when the button is deactivated.

SHAUN

[diannone]

i was going to do that but ive also heard that slight deveations in the supply voltage will cause the dme to act up, 14.7, 12, 14.7, 12..... i have enough fun with this car with out looking for more. :-)
just a thought. a micro switch on the throttle?
try it im curious.

[TheStig]

hey ahmet seeing that i yanked the AC out of my car, is there a way i can remove that gay nob in the middle of my console and put a voltmeter there? or an air ratio fuel monitor gauge? if so I also wanna know if i can wire the radiator fans to the regular air fan for it to turn on the same way it does when you turn the AC knob on....



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Porsche. Es gibt keinen Ersatz.

[mlue]

My 2 cents, but isn't disconnecting the alternator on a road car a little extreme also putting a electromagnetic clutch on the alternator will add rotating mass to the alternator pulley which will probably defeat the original purpose of reducing paracitic drag on the engine. I donn't thing there is much to gain here. Undersized alternator pulley maybe a better choice, the mustang crowd goes this.

If you want better response and quicker times try lightening and reducing unsprung weight of the car. This works wonders for autoX. Someone on this board did this and reported some pretty good results. Cheap too !!!

Mark
'86 944NA

[This message has been edited by mlue (edited 09-17-2001).]

[EGSMachine]

Originally posted by mlue:
also putting a electromagnetic clutch on the alternator will add rotating mass to the alternator pulley which will probably defeat the original purpose of reducing paracitic drag on the engine.
[This message has been edited by mlue (edited 09-17-2001).]

the Parasitic drag of the rotating mass won't take until the the clutch is activated. the clutch sits on the A/C body, not on the pully.

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84-9445m
Porsche, "Overtly Masculine Feel".

93-325is 5m;
driven daily.

[EGSMachine]

oh yeah,
after puling my Intake from the head, there is alot of room for improvement in that area alone. i have not gotten to the throttlebody, as i am too tired to mess with it tonight. but if the runners to the head are an indication, i would say that 10 hp is a real possibillity.

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84-9445m
Porsche, "Overtly Masculine Feel".

93-325is 5m;
driven daily.

[fireboss]

Jacobs electronics sells a kit that will work. Check it out Jacobselctronics.com

[Ehab]

I agree with diannone,
the role of the regulator will be eliminated at WOT if you disconnect the alternator, and hence the fluctuating voltage might be really harmful to the DME.

Do you have actual figures of how much torque gain you would get from disconnecting an accessory such as the alternator?

E

[Magnus_944]

Maximum output power from alternator 90A*14V = 1260W. Alternator efficiency ~75% I guess. Maximum input power 1260/0.75 = 1680W => 1680/735 = 2.29HP saved
I don't think it's worth the trouble since most of the time we don't use all 90 amps from the alternator and savings will be less.

My 0.2 SEK
/Magnus

[944pilot]

one important thing to remember if doing the alternator thing is that the ignition system (along with fuel pump, etc) is drawing a lot of juice at WOT (the system in a relatively hot V8 draws up to 50 amps). If your alternator is off line, you may be losing power rather that gaining because of the loss of iginiton power and fuel pressure.
just my .02
Brian

[Blackfoot]

i would check with 944 racers to see what they have done with the alternator. just about all of the tricks you can think up have been tried on the track, which is the ultimate testing ground.

[Ehab]

I'm totally behind Magnus ...
2.3 HP is not worth it, especially knowing that humans cannot detect any power change smaller than 7HP that clearly.

E

[adrian jaye]

Start messing with the alternator and your asking for trouble.

you won't get any gain's at all. you've still got a ruddy great belt runnnig around it.

As for monitoring the voltage ( previous early reply), it does that automatically, funny enough it's called a voltage regulator.

leave it well enough alone as Mr.Ferdinand designed it

[drew1]

Ahmet,

Been reading Alternator posts with interest. With your MAF vane mods you may be able to pick up power with intake & trottle mods.

drew1

[EGSMachine]

Port maatched the intake runners to the head. i took off over an 1/8 of an inch in some areas. also, the inside of the runners is a dirt collector. thry cleaning that out for a coupls more ponies.

http://www.ruffstuff.com/index.html

has flex hones that can doit easily, and give you some "polishing".
e


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84-9445m
Porsche, "Overtly Masculine Feel".

93-325is 5m;
driven daily.