Underdrive pully kits

[BlackOnBlackATX]

im not saying it wont disconnect the electrical load but youre still spinning pullies and thats whats holding you back. the ac still shuts itself off and if the fans not even a problem over 40mph as mentioned then why bother? not taking the electricity from the alternator isnt going to make the car faster, it still takes the same amount of friction to spin the bearings inside and your belts are still attached to it receiving drag, true your making heat when you spin that fast but at 7000rpm load or no load your still producing massive amounts of heat. and trust me, i do know what im talking about. i work in a power plant as an electrical engineer so i understand a thing or two about generators. give us a better explanation of what goes on here, because if youre right then i will concede to logic and admit im wrong and ill do so happily, otherwise i reserve my right to call bs when i see it.

<small>[ January 07, 2003, 09:59 PM: Message edited by: BlackOnBlackATX ]</small>

 

[Mike Kopstain]

It's a trade off. As with any mod, the owner of the car will determine his or her driving characteristics and decide which product suits them. I don't know how old you are, but I would suggest that a lot of us young un's spend a LOT of our driving time with the right pedal planted right angainst the floorboard. If you are looking for power all the time even when you are not a WOT then this isn't for you.

Now are you telling me that everytime you accelerate you turn off the A/C? Probably not.

The whole premise of the product is that it is cheaper, easier to install, has NO side affects, and is more effective, albeit not across all loads as underdrive pulleys are.

It's a hard sale to fight, and rightfully so, because it offers a great benefit. Let the numbers and the buyers speak for themselves, because I'm quite confident that a good portion of SHOforum members will soon be looking at a VAK for their next mod. (Or so I hope )

<small>[ January 07, 2003, 09:59 PM: Message edited by: Mikeys_Taurus ]</small>

 

[BlackOnBlackATX]

i am more than willing to listen to buyers, like i said if im wrong im wrong, the numbers will speak for themselves, as far as the AC goes, it disengages at WOT to protect itself, thats standard knowledge wink you can find it on shotimes.com if you need something concrete to believe me.

ps- i hope this is still a "friendly fight" im not trying to make enemies but it is in my nature to play devils advocate a little too far. just so you know its all in good fun.

<small>[ January 07, 2003, 10:05 PM: Message edited by: BlackOnBlackATX ]</small>

 

[Mike Kopstain]

BlackOnBlackATX:
im not saying it wont disconnect the electrical load but youre still spinning pullies and thats whats holding you back. the ac still shuts itself off and if the fans not even a problem over 40mph as mentioned then why bother? not taking the electricity from the alternator isnt going to make the car faster, it still takes the same amount of friction to spin the bearings inside and your belts are still attached to it receiving drag, true your making heat when you spin that fast but at 7000rpm load or no load your still producing massive amounts of heat. and trust me, i do know what im talking about. i work in a power plant as an electrical engineer so i understand a thing or two about generators. give us a better explanation of what goes on here, because if youre right then i will concede to logic and admit im wrong and ill do so happily, otherwise i reserve my right to call bs when i see it.

I'm sorry, but you are wrong. Motors work via magnetical energy correct? The more energy created the more power the motor has. This is inversly the case with an alternator. The more power required from the alternator, the harder it is to spin. Release the load, and it free wheels. Sure there is still power needed to turn the internals, but no where nere what is needed when there is a load on it. I mean, this is really basics when it comes to motors, so I'm not sure why this is such a hard concept to grasp, especially if you are an electrical engineer.

And yes, it is a friendly fight, but it would have been nice of you to ask your questions before you claimed that we were selling people a hollow $130 aluminum box. I wouldn't sell it if I didn't have confidence in it.

<small>[ January 07, 2003, 10:16 PM: Message edited by: Mikeys_Taurus ]</small>

 

[V6&V8SHO]

I was in a vulcan taurus with the VAK system and it did make noticable difference. It gained most of its power at the top end.

 

[BlackOnBlackATX]

well i must concede to you on this point, when i sit and think properly about stator and armature and field currents it does take more force, so i apologize for speaking without thinking, im sure a couple of my old teachers would put foot to ass if they knew i said that. but im still curious as to how much force we're really talking about, because 4000-7000rpms is alot of speed over that little pulley and your talking about quite a bit of inertia already in the system, all your doing is maintaining it, not breaking a static barrier from standstill for a high current draw which take much more energy to do as you pointed out. for guessing purposes lets say that the stock pulley is 4 inches across. i might be off or dead on im not too sure. if youre serpentine belt is pulling with even 100lbs of force at 5000rpm, and i happen to think that might be underrated but again not sure, your still talking 200ft-lbs of torque on that pulley. thats alot of torque. so how much do you say the alternator is fighting against it then? because at 7k rpms youre talking alot of torque on those wheels, and i dont think that little alternator can supply that much back EMF. ive only seen watermelon sized AC generators producing that much backtorque. now were getting into pure lack of efficiency talks. i wish i had some real alternator numbers, ill see what i can look up tommorow, maybe ill give ford a ring but i doubt theyll have what were looking for. but i concede to say you may be getting some benefit, but i doubt as much as you would believe. hopefully someone will have a dyno graph to prove me right or wrong.

<small>[ January 07, 2003, 11:29 PM: Message edited by: BlackOnBlackATX ]</small>

 

[doucebag]

What your saying makes sense...But what do you mean wide open throtle? I know what it means, but with the VAK is it hard acceleration, like a hard take off but not right to the floor, or is it what it says WOT? I'm 22, and like you said i like the speed and power but not at every stop or straightaway. All i'm trying to understand is what you mean buy WOT. Like if it is WOT under a hard take of , or passing, or 7500rpm.
thanx
kevin

 

[Mike Kopstain]

First off, WOT is foot to the floor. The good times.

Blackonblack, no worries... To prove a point. Thing about during the summer when you have the A/C on. Step on the gas and turn the A/C off. There is a noticable power increase. This is because you are no longer powering the compressor, but rather just free wheeling the pulley. The same applies for the alternator. By taking off the electrical load, you are just free-wheeling the pulley and the alternator internals. The major increase in power is that the alternator is no longer fighting to move. Once up to speed, it takes very little energy to keep it moving. That is not the case when there is current running through.

I think you are putting a little too much emphasis on the pulleys. The underdrive pulleys job is to make the accessories spin slower, thus releasing some of the power they use. They are doing exactly what we are doing, just less efficient, and in a different way. Like I said, if all those pulleys were free-wheeling with no accessories attached to them, you could mix and match sizes and there would be a nominal difference in exerted energy to spin them. ****, you could get a huge belt, and a bicycle rim and run it around there and it would make little difference. Perhaps an excessive example, but gets the point across nonetheless.

Maybe some day when I have a little more capital I'll send you one to try. I'm confident you'll send me a check for the purchase price.

<small>[ January 07, 2003, 11:54 PM: Message edited by: Mikeys_Taurus ]</small>

 

[BlackOnBlackATX]

all i meant by talking about the pullies was considering the amount of force the engine is supplying to turn it to begin with, it would be helpful if somewhere we could find real world numbers to see how hard it was fighting the alternator when loaded. how exactly does the unit disconnect the alternator? im still curious as to the operation aspects. im assuming you have one on your GL, ever get the chance to dyno it? If im ever in Illinois (slim chance but you never know) i will buy you a beer and we'll check one of these bad boys out. i mean im all for horsepower where you can get it without doing open-engine surgery, but i think you can understand by now that im a skeptic at heart.

 

[jelloslug]

The theory behind the VAK sounds valid. One thing to take into consideraion is that the load applied to the alternator is not constant; it depends on the electrical demands at the present time and the condition of the battery. Lets assume that the alternator is at full load (I think its a 120 amp alternator) that around 1750 watts of power out. The alternator is probable aroud 80% efficient but throw the regulator into the circuit and it will probable drop to around 60% efficient. So 1750 watts out would take 2917 watts in to make and 2917 watts is 3.9 HP. I did not add in friction and windage losses (what it take just to spin the rotor) so in theory, according to my educated assumptions (I'm a motor engineer by trade), there is the possability to free up around 4 HP from the alternator with this mod.

<small>[ January 08, 2003, 11:46 AM: Message edited by: jelloslug ]</small>

 

[BlackOnBlackATX]

well, judging by all that agree then it looks as if i may have to give into the vak craze, although i still wonder about the actual mechanical horsepower lost through the resistance of the alternator. but since the A/C and the cooling fan are null points since the A/C shuts off and the fan aint really robbing power or even running at WOT and your really only freeing the 4hp (taken from jelloslugs testimony) from the alternator, then why not spend $60 and get a MAF on ebay from a mustang and get the 5hp there?

 

[jelloslug]

I was just about to post about not need to cut out any thing eles . The 4 HP is just the power need to generate the 1750 watts and does not include the power needed to spin the alternator. The only way to free some of that up is with underdrive pulleys.
It might only be 4 HP but add that to you MAF, underdrive pulleys (why not do both ) and other small HP adders and it starts to add up.

<small>[ January 08, 2003, 12:11 PM: Message edited by: jelloslug ]</small>

 

[BlackOnBlackATX]

oh hells yeah if you had the free cash and you were able to do just the three of those mods for arguments sake then youre talking about 15-20hp if the numbers are true. if you really had the money to do an exhaust then or something or had cams put in. brutal. but is there anyway i can see a technical explanation of how it disconnects the alternator? does it totally isolate the connections to the field windings and the battery outputs or does it just choose one or what?

 

[SHOZ123]

The VAK is a "real world" performance device. By this I mean it is available whenever needed. But only on demand. To dyno such a device it needs to be done with a full accessory load. Meaning A/C on, all electrical loads and the PS working which is really hard to do on the dyno.

It will turn the A/C off sooner than OEM. And I do recommend a good deep discharge battery. I consistently run faster than other V8 SHOs and many have the same mods except the VAK.

Here is a summation of what it will do.

The big differences between the VAK and UDPs are

1. It is only on demand

2. it is a 100% load reduction on the alternator

3. it turns the A/C off sooner than OEM

4. at start up there is a greatly reduced accessory load for easier starting

5. it is easy to add more devices that can be controlled electrically

6. there are no ill effects because of a slow idle speed

7. it is very easy to install

8. it can be universally applied to almost any car

9.it can be easily disabled

10. if it fails it will default to the off position meaning normal OEM
operation

 

[jelloslug]

You really only need to unhook the main wire. That would disable the alternator electricly. You could test the theory by unhooking you alternator (for a short period of time) and drive around.

 

[Mike Kopstain]

You also have to remember that these have to spin up. That takes more power than it does to keep them spinning, and that is when you need the power the most (off the line) and also where the VAK is most effective.

It's hard to measure what is required to start those accessories going. This is the type of mod where you have to look at it and kind of read into the numbers. While the hp numbers that you gain may not be staggering, the seat of the pants dyno tells you otherwise.

 

[bradman]

Mikey,
When are you going to answer doucebag's last question?? Does the accelerator have to be mashed to the floor for this thing to kick in? Can it be adjusted to kick in say at 3/4 throttle?

 

[RI-SHO]

Hmmm I wonder what UDP's, VAK, and a Hyper Ground wiring kit would add .

Since you guys brought up small power adders, i'd like to throw in the HyperGround System from Sun Auto., there dyno proven on there website and on tuner magazines like Import Tuner. On brand new cars just the wires themselves free up 4-10FWHP depending on the application. A few TL-S' on the forum I am on Dyno with 8FWHP more and V6 accords with simliar 6FWHP increase, might be small but like someone else said on this thread, it'll just keep adding up.

Sounds like something to think about if your already considering these "small" power adders.

<small>[ January 08, 2003, 08:35 PM: Message edited by: RI-SHO ]</small>

 

[Mike Kopstain]

bradman:
Mikey,
When are you going to answer doucebag's last question?? Does the accelerator have to be mashed to the floor for this thing to kick in? Can it be adjusted to kick in say at 3/4 throttle?

Sorry about that. I must have missed it. typically it kicks in at about 80 - 85% throttle and stays on until lower than that amount.

You're "battery" idiot light will let you know when it's working. You can just make a little "VAK" icon to go in there that lights up.

I just installed another one today and the guy liked it alot. I'll have him post. He posts on here quite a bit.

 

[LaTechSHO]

essentially we are talking about a relay to shutoff power to the alternator, a relay to shutoff the a/c clutch power, and a relay to shutoff the power to the fan relays....... correct?

hook up power to those relays to something that senses WOT or setup something to read the output voltage of the TPS and fire the relays accordingly and you have your mod.... if i am reading it right....

sounds reasonable.... and for the record.... the alternator does in fact create a reasonable drag on the belt..... i see it every day on an alternator bench tester.... (don't know how much drag) ... but enough to make a small difference over a broad rpm range .... i don't know the electronics of the a/c cutout .... but i would imagine our EEC-IV does some sort of processing (and lets face it they aren't pentium IV processors) so there may be SOME delay.... as for the fans.... that is the hardest for me to rationalize..... especially when you are already cutting power to the alternator.....

anyway... sounds like a good idea....and i'd be more prone to do THAT than UDP's just because i don't like the idea of my accesories not turning as much as they should at idle.... causing more stress on my $100 power steering pump than necessary and the like.... i just don't know if i'd spend $130 on it.... to each his own....

Louis