Biddles

iTrader: (2)

Looking for advice here. I don't know exactly if bigger is better in the alternator upgrade world. The stock alternator is 100 amps from what I've seen, so I thought 150 would be a good choice, but after searching on ebay I found 150, 200, 220, and 250 amp rated alternators. My audio is upgraded, but I haven't done "The Big 3" upgrade yet, and I've been getting dimming lights, and a slight whine. I believe it's the original alternator in my car(1996 400, 135K).

My amp is an Alpine PDX-9 putting out 100 watts RMS x 4 + 500 watts RMS x 1. Completely new audio all around, I have a build thread here....

https://www.clublexus.com/forums/sc-...o-upgrade.html


Currently I'm only pushing a basic Kicker CVR 10" in the stock location, but thinking of going for a Sundown Audio 12" for the trunk for better bass quality, and I know if the lights are already dimming they'll only get worse.

gerrb

iTrader: (34)

If you can afford a 250 amp alternator , go for it. That will give you a lot of room for whatever stuff you will add for your electrical system in the future.

TXMAG

iTrader: (1)

Bigger is better when it comes to upgrading your alternator - Put in the biggest one you can afford that will physically fit the space. That being said, buy something of decent quality. I’ve seen cheapo alternators with faulty voltage regulators wreak havoc on electrical systems.

Now, without getting into things like efficiency of the amplifier, true voltage supplied by the car’s electrical system, etc., your PDK-9 will pull probably pull 65A-80A pretty consistently. The rest of your SC400’s electrical system probably needs about 50A. At a minimum, you should be looking at 150A alternator based on your current needs. 80A (audio) + 50A (car) + 20% (overhead) = ~150A.

Also, since I didn't see it mentioned, you should probably be running at least a 4ga power wire from the battery to the amp. Anything less and you may be choking power delivery depending on the length of the run.

In regards to changing the sub, it will have nothing to do with your dimming issue. The dimming issue is strictly power related. If you get a bigger amp to drive a bigger sub then yes, your dimming issue will get worse.



***MATH***


If you’re interested, here is some of the math behind the calculation that will help you determine future needs. Once again, I’m going to keep this pretty basic. The formula you want to remember is:
P = V * I
P= Input power in Watts
V= Input Voltage
I= Input current in Amps

Based on what we know about your amplifier (RMS rating is 900 watts @ 14.4V based on the PDK-9 spec sheet) we change the formula slightly to figure for I. The formula now becomes:
I = P / V
I = 900 /14.4
I = 62.5

62.5A is a sort of “perfect world” rating though. When you start getting into the many variables in a car audio system this current draw almost always goes up.

It’s also generally assumed that a car needs 50% of the amperage provided by your stock alternator to run its own electrical systems. If your stock alternator is rated at 100A then figure you’ll need~50Amps for your car’s electronic systems.

So, figure the sum of your audio system + the car’s electric system and add 20%-50% for overhead and you’ll be in the ballpark 99.9% of the time.

Studiogeek

iTrader: (6)

I love this forum...... because of THIS ^

Studiogeek

iTrader: (6)

Who makes a Gerrb approved 250 amp?

(so I can eventually drown it in PS fluid)

I have a Mechman in the 400 but I want a 250 for the 300. Mechman does not offer one and they are pricy.

gerrb

iTrader: (34)

lol , regardless who makes it , you don't fix that PS fluid leak on your SC400 , it is not gonna last.

I see a lot on Ebay but I have no experience from them. Check PowerHouse Racing though . They have good ones.

I have a Mechman 240 in two of my cars and so far so good.. not 250amp though .. only 240amp which is good enough for my needs.

1A1

Don't waste your money on aftermarket stuff. You can use a 150amp alternator out of a 2006 Toyota Sequoia Limited or the Lexus equivalent (GS460). These can be found on amazon.com. It will require 7mm to be machined from the back to fit with the GE engine's bracket. There are some threads on Supraforums that show you what needs to be done, Ie specific part numbers, etc. This alternator will put out more amps at idle than any aftermarket alternator available.

Steve K.

Kris9884

iTrader: (7)

I bought 2 alternators for both my SC's from a guy on eBay by the name of "eagleautoelectric". They were both 200 AMP and I ran a new 4GA power. They were awesome. Before upgrading to the 200 AMP, my headlights and dash would slightly dim to the beat of music with my upgraded sub and amp. Now its perfect. I would recommend him to anyone, PLUS, no core charge.

95SC3T

iTrader: (3)

1A1 - I am going to be doing the alternator upgrade you speak of. I just Ordered my parts today.

Studiogeek

iTrader: (6)

I was just kidding man ;-)

I have a Mechman in the 400 right now. They are great when you are running but as mentioned above, don't put out much at idle.

I was thinking about the Toyota Alt mentioned above. I wonder how large an amp might be safe with that setup and accessories? If it puts out more at idle, that's what i need. I sit in LOTS of NYC traffic.

SG

Studiogeek

iTrader: (6)

Steve,
Couldn't find the OEM alt article but I did find Mechman fighting back a bit on the idle output figures.

A guy posted about the Mechman alternators and included an email he got from them.

----------------------------------------------------------

Hi all, our oem alternator are old technologies, this compagny Mechman alternators sell 240 to 370 Amp dual regulator alternator using newer 6 phases technologies ! For me it's not total amps the problem, but more idle amp....

http://www.ebay.com/itm/93-94-95-TOY...f88757&vxp=mtr

Deliver twice as much power at idle.

http://mechman.com/

I'm preparing to oder a 240A unit from them, they also give 2 years warranty.

I didn't liked the eagle auto recent poor review and for me 240Amps is more than enough, but I still need to compare to their 370A

We offer an outstanding 240 amp S series unit that is a direct bolt in upgrade for your Supra. We sell tons of them for Street / Racing applications, they are significantly more durable, and have better high RPM capability than the OEM 3 phase toyota alternator. They have twin rectifiers with 12 diodes (OEM unit only has 6) so they dissipate more heat and last longer. Thanks to the 6 phase technology, the unit makes such good low RPM output, that we don’t have to use such a small pulley on it for it to maintain good output at 800 rpm. This means that the alternator will not be over-spun at your 7500 rpm redline like most other high output alternators for 2JZ. We also include a 1/0 gauge pure copper terminal for the necessary upgraded charge cables (sold separately). You can read more about the S series units here, the unit in the main picture is the 2JZ alternator: http://www.mechman.com/index.php/products/s-series.html

The 240 amp unit is very reasonably priced at just $399, is made in the USA with OEM late model Denso parts, and comes with a 2 year warranty.

I asked more questions to compare the 370A unit to the 240A unit for idle amp, heat generated, hp draw and installation/size<

------------------------------------------------------------------------------------

I actually hope the Toyota is better.....

lexforlife

iTrader: (7)

Mechman user here as well , I have 170amp version and put out 135amps at idle , another friend here has 1300hp supra using 240 amp and puts out 170amps at idle and has been trouble free

JRD1957

Hi-I sit in lots of Houston traffic too and need to upgrade my alternator. What did you end up doing?

JD

KahnBB6

iTrader: (5)

I'd be happy with the JDM-OEM 130 amp alternator for late model 1JZ-GTE's but they are apparently horrendously expensive to import.

I'm still trying to decide what TT compatible alternator to go with for mine. I don't have much extra electrical load with the factory 80-amp SC300 alternator. A couple of electronics may be added in the future but not a powerful stereo. I've read about all of these options but I may just go factory TT 100amp to keep things simple and OEM... even if it is old technology.

But the Mechman and Sequoia 150-amp options do sound very compelling. JRD's reason for upgrading makes me take note too since L.A. has plenty of traffic to sit in.

GiulioTJ

Hello,
I have a Lexus is 200, running on LPG and it is using still after 20 years the stock alternator 90amps.
Unfortunately, I have changed 6 batteries in almost 11 years.
I have reasons to believe that this stock alternator is not sufficient to recharge the battery and was wondering if changing it with 250 amps one will be a problem?
If someone has a little piece of advice please feel free to add a response.
Many thanks
Giulio