Honda Prelude Forum banner

1 - 11 of 11 Posts

·
Administrator
Joined
·
5,227 Posts
Discussion Starter #1
The other day, I noticed a slight problem with my stock alternator, which is grossly underpowered for the stereo system I'm running. The issue this time was that the terminal bolt came loose, and it almost managed to arc completely through the stud. Go out and check yours regardless of whether you're a nutcase like me trying to fit silly alternators on their car.



I've been considering a high output alternator for a while, but there's really not much quality out there for the preludes aside from fitting a massive GM alternator on there. I wanted something as plug and play as possible, with a higher amperage. Yes, I'm aware my sound system will use over 130 amps, but it's better than putting another 90 amp alternator back on.

The other purpose of this is to locate the alternator higher in the engine bay, into the area where the power steering pump would go. My turbo currently has no air filter as the alternator is in the way. I'm trying to put an end to that as well.

**** I AM NOT DONE WITH THIS PROJECT YET, WILL UPDATE AS PROGRESS IS MADE. *****

Stock H22 Alternator: 90 Amps
1999-2000 Odyssey alternator: 130 Amps

From a wiring standpoint, it's plug and play. The connector on both alternators is the same.


The new alt

Things immediately apparent:


  • Same connectors, different locations. The positive post is on the back of the odyssey alternator.
  • The mounting points are in different locations, and are different thicknesses. Pivot bolt side is thinner than the H22 alt, tension side is thicker.
First order of business is going to be ensuring the pulley is the same distance from the bracket when mounting the new alt. I measured from the back of the bracket to the pulley location with the h22 alternator:



I then measured the odyssey alternator. The pivot bolt side is considerably thinner than the h22 equivalent. I put the bolt through, and slid the alternator back and forth along the bolt until I had the pulley in the correct place. I took a few measurements and found a combination of washers that would locate the pulley in the correct spot. I noticed that I had room on both sides, and since I wanted to raise the alternator up towards the PS pump area, I needed to extend the bracket to do that.

In order to get the added height, I picked up some flat metal stock of what I considered appropriate beefiness, and cut two 2.5" long sections. Keep in mind, at this point, this is a mock up, and not all my holes are centered.

Off to lowes for some bolts with the same thread pitch as the pivot bolt, as well as some washers, lock washers, and nuts. Shortly thereafter, I arrived at this:



Just by using appropriatley sized flat stock, and a few washers, I managed to locate the pulley in the correct spot.

Now, onto the problem side:




Moving my top bracket around... So... friggin... close. Wouldn't have mattered either way, as the angle of the adjuster is different. But how can we adjust the tension on the alternator, while doing zero cutting on the bracket itself...

The answer was a 3" piece of flat stock, similar to the top bracket, as well as a metal spacer (I really, really thought about using a socket) that I found in the bolt bins at lowes. I trimmed it down slightly from 1" to about 3/4" to get everything to fit, as well as spacing things out with a single washer between the adjuster hook and the flat stock.



So, the alternator is mounted. Over the next few days as I have time, I'll be removing power steering from the car, as well as mounting the bracket and seeing where things lie. Once everything is in position the way I want it, I'll be redoing the brackets making sure to drill holes centered, and I'll have the pivot side welded to the mount itself, as well as braced with more flat stock to ensure it stays put. Stay tuned for more updates.
 

·
_
Joined
·
2,494 Posts
so, if you've taken out power steering, couldn't you just use the stock alternator?
 

·
Administrator
Joined
·
5,227 Posts
Discussion Starter #3
The 90 amps put out by the stock alternator isn't enough to run the stereo in my car. I've got more than even the Odyssey alternator can put out at 130 amps. I end up charging my battery once every two weeks with a trickle charger as a result. I'm tired of the oppression, we're moving it to 3 times a week. The odyssey alternator isn't much larger than the prelude one, and in the stock location would be a reasonably easy fit with a similar bracket to what I have made.

The reality is, a quality, non ebay junk part alternator that's high output is expensive. Like, $800 for an alternator expensive. The eBay alternators may produce 130 amps (@ 3000 RPM, who the hell has a 3k idle..) but that's largely due to messing with the regulator on an otherwise rebuilt Chinese alternator. Yes, there are other options, like powerbastards Fitzall 220, which, allegedly, fits all the things, we're still talking $350 for an alternator. Still a DIY bracket on Hondas, or any inline 4. They're all retooled GM/Ford/Chevy truck alternators at the end of the day. Silly wiring is required to keep the alternator light from tripping, if that's possible at all. I hate annoying lights on my dashboard telling me things are wrong. I'm not willing to accept a glaring alternator light at all times. There must be a better option.

Hondas are made out of legos, and as such, most of the alternators use the EXACT same wire connector. Odyssey alternator plugs right in. Literally, plugs right in. Shouldn't trip the alternator light. This means the guys who don't want to go insane and spend a ton of money buying a high dollar alternator to adequately solve a common problem. I've known I've needed more power for a LONG time. It's simple math, you take 150 gallons of water per minute out of a container, and only refill it with 90 amps per minute, you're going to run out of juice sooner or later. Eventually, you learn enough that you can mathematically prove that a 1 Farad cap isn't doing a thing but keeping your headlights powered. If you don't care to do the math, install a voltmeter in your car and blast a high powered stereo for a few weeks. You'll see the battery start dipping and after a while, you'll start to hear what happens when the battery is simply tired of not being charged with enough power to keep up with demand.

Granted, running a larger secondary wire to the battery positive is ALWAYS a good idea when increasing amperage, So that will 100% be done. These cars were mass produced, and realistically, having any gauge more wire than necessary to carry the specified amperage is a cost of millions to Honda.

That said, there are plenty of people with a 1000w stereo (at peak, draws 72 amps by itself (*1), which is more than capably handled by a 130 amp alternator. The fact that it doesn't cost that much more than a factory alternator is a HUGE plus. I've had the turd break on me, and not had the cash to buy the part I really wanted to get before. This hopefully drops the added $300 to get a little more juice than stock.

*1 - In car stereo, unless you're sitting there playing test tones (SPL BRAH!), you're NEVER seeing peak. Music is a dynamic source, and almost never peaks fully, and never for a long time, that said, 50% of peak amperage is still about 35 amps. I'm at 2500w. Calculate your own draw - http://www.supercircuits.com/resources/tools/volts-watts-amps-converter. Voltage is 13.8 (even at 14.4v you're still at 70 amps) An extra 40 amps is enough to cover 1000w in addition to the output of the stock alternator.

The bracket I made fits with power steering removed, but doesn't solve my issue of locating the alternator higher in the engine bay to accommodate an air filter on my turbo as the tensioner arm is still in the way. A little welding and this solution would work for 95% of preludes out there, and provides a proof of concept. Before I ran this bracket in any way shape or form, I would sandblast the stock mount, and have the entire assembly welded together with proper spacers instead of washers. It's almost got the alternator touching (bout 1/2" clearance) the mizu radiator I have, which is considerably larger than stock. I'll post pictures when it's light out tomorrow.

I've been talking with Shocker5thgen, and he believes he can make a bracket that comes much closer to the engine, and moves the alternator even higher. This solves my clearance issues, as well as opening pandoras box for anyone who may not be running a turbo, and might want 260 amps using spare Honda parts, and need the space the stock alternator provides. It seems an easy enough endeavor, I just lack the tools and resources he has, but it shouldn't be excessively difficult.

TL;DR - Stereo loud, needs more powah. Minivan alternator bigger than prelude alternator, costs about the same.
 

·
Registered
Joined
·
500 Posts
This is the most interesting project I've seen written up in PP for a long time. I'll be following it for sure. Thanks for going through the extra work to do a write up....
 

·
Administrator
Joined
·
5,227 Posts
Discussion Starter #5
Here's the pics of everything mounted up. I didn't pick up a belt for it as the bracket I'll need is going to require an even higher mounting point, but those of you without turbo setups shouldn't have any issues mounting one of these after welding the flat stock to the bracket.

Please ignore the rats nest of wiring and oil and vacuum lines, I had to move things around while doing the project and haven't got everything back in place quite yet. You can see my issue with mounting an air filter in the last picture, which is why the stock location will not work for me. I don't have all the mounting bolts snug because it's raining here and I don't feel like tightening them when I'm just gonna have to go and remove them tomorrow to ship the alternator to shocker5thgen.




 

·
Registered
Joined
·
1,243 Posts
I would have just taken my alt to a rebuilder and had them make it 130AMPS. I took my 65amp alt from my Camaro to one and had them bump it up to a 105amp so I know it can be done.
 

·
Administrator
Joined
·
5,227 Posts
Discussion Starter #7
I would have just taken my alt to a rebuilder and had them make it 130AMPS. I took my 65amp alt from my Camaro to one and had them bump it up to a 105amp so I know it can be done.
Yeah, it's doable on domestic alternators. I couldn't find anyone able to do that to a Honda alternator. It's a matter of parts availability apparently.
 

·
Registered
Joined
·
7 Posts
I like where you are going with this. In regards to the electrical draw on the alternator coming from your stereo system... Do you have a capacitor set up for the power going to your amp/s?
 

·
Registered
Joined
·
1,243 Posts
Yeah, it's doable on domestic alternators. I couldn't find anyone able to do that to a Honda alternator. It's a matter of parts availability apparently.
Is the Odyssey alt physically larger then the Prelude alt? If they are the same size couldn't you just transfer the guts from the Odyssey casing to the Prelude's?
 
1 - 11 of 11 Posts
Top