when changing the underdrive pully, i know it has an effect on the charging system....especially if you have a stero system so the question is ....

Is there another pully (and what size) to put on the alternator to keep it charging the same without losing too much off the underdrive pulley?

no need for flamers just a honest question...and yes i did a search and did not find what i was looking for.....

 

Try a Cap.. that will help


You answered your own question on this one... A different pulley on the Alternator will cancel the effects of the UDP. trying to figure out what pulley size will have the least effect is a mood point.


I am not gonna flame you, however I and several other members have discussed this before, many different posts. Maybe you just did not get the right combination of words. But, There are your answers

 

"You answered your own question on this one... A different pulley on the Alternator will cancel the effects of the UDP. trying to figure out what pulley size will have the least effect is a mood point."

For future reference, it is moot, not mood, if I read your post correctly. If you meant moot to insinuate the use of a larger alternator pulley with an UDP as being of no practical importance, or to create a case of irrelevance, you mean moot, and not mood.

And you are NOT entirely correct. The alternator is only ONE source that uses rotational power. There are a number of accessories driven by the UDP. And the loss of weight alone at the UDP would create some gains in hp. Agreed, using an UDP while plus sizing another pulley, especially the alternator, which is a high drain source is not wise, but, he would probably only lose about 25-33% of the gains he would get by using the UDP alone. Granted there are only about 10hp to gain by using an UDP on a stock 4th gen Maxima, and with a larger alternator pulley, that would drop to about 6-7hp, with the UDP costing about $200 plus belts. But 6-7hp still isn't all that bad for $200, and the gains mentioned at 10hp are pretty conservative. I believe someone posted dyno gains of around 15hp from this board. And that would then make gains of about 10hp, even with a larger alternator pulley.

Yes, for optimal gains from the UDP it would not be wise to increase the diameter of any other pulleys, but no, you are incorrect, he will still get moderate (for the price) gains.

 

Thank for correcting that. Good thing you are here to help out my spelling.

The percentage of loss would depend on the pulley size of the alternator. And you know which pulley will get the 25-33% loss?

Really, I am just curious to which DYNO you have gotten this 10 hp on a stock maxima from?

See above post

You "believe" or know? Which one is it? You seem to have alot to say for someone who does not know for sure what the gains were and what the mods were. And BTW if you are talking about the same member I am he also DID change his y-pipe so the dyno numbers will be off. Again if you are talking about the same member I "believe" you are.

What is moderate? For the price?

I will say this, if he gets 5 PEAK HP from the UDP, puts on a larger alternator pulley and looses 25%, your number mind you, he will gain a WHOPPING 3.75 HP for $200, your price.

Sounds like a big loss of money to me. I know that custom work in Atlanta is about $75 per HP. So going off of that number he just saved himself $25.

And before you say it, other mods will increase the HP output, IE supercharger/nos, but he did not say that.

What about my post using a CAP?

Did not have to much to say about that, huh?

Please show me the dyno of 10 HP for a stock maxima and I will buy a UDP tonight.

Until then, You might want to check to make sure your qouting actual numbers.

BTW thanks again for correcting my grammer/spelling error.

 

I don't think you'll have any problems. I've have my UDP on the car for a year and half with no problems. I'm running a 700 watt RMS total system and never had my lights flicker. I'm also running an Optima Yellow Top battery, so that probably helps, and I have 1.0 farad cap sitting in the box. The Optima Yellow is a deep cycle battery that can be drained and recharged much faster than another battery. So in my case, I don't need as much power to run the alternator or to recharge the battery.

As for the gains on the UDP, I don't think a dyno will prove much. I believe a time slip will though. I notice my 1st, 2nd, and 3rd gears running up the RPM's much faster. I also lost a lot of rotational mass when I installed the Wilwood brake kit along with my fairly light SSR Integrals. On the dyno, I don't think I gained more than 10 hp, but on the 0-60 and 1/4 mile, I must have shaved .3 sec, .5 sec respectively. Ask OgreDave, he's really the only witness as far as the speed of my car goes.

 

I was not trying to ask you for a dyno or proof. Just Sin. I do know people with UDP's "normally" have higher trap speeds in the 1/4 mile.

I am not in the UDP haters or lovers club.

and your first paragraph backs what I was trying to say.

 

thanks for your help guys.....the battle can go on now.....proceed