mtnman82

eniac - did you have to do any adjusting to make the pulley line up?

That woul be really, really cool if CEP made a mount for doing this. If so, I'm guessing it would be for a specific alternator? I was just looking to see if any venders offered mounts or kits for doing this mod, but didn't come up with any alternatives (I also want to keep my A/C - looks like Lindsey's racing alternator is sans A/C).

333pg333

Stephen, you still running around at 35psi? How's your headgasket holding up? Any special secrets you'd share with us? Sorry about ot. Just don't see you round these parts much nowadays.

I thought the weight differential would be quite a bit greater too...

eniac

I might have had to shave a tiny bit off one side of the top mount. I don't remember, it I did, it was really minor. It all fit pretty well for me.

I can modify stock brackets if anyone wants for $90, or fab an entire new bracket for about $250. Its not my intention to make any money on this but it does take time and material.

I was running 27psi with 35 momentary boost up until last november when. I stopped driving it for winter. HG was holding up just fine. I'm making huge changes on the car including trying to afford a standalone. The klr and dme are now gone. I've been very busy making everyone elses 951 faster so haven't had much time at all to work on mine. Plus another daughter so have been busy with. both our 1 year 3 month old and 2 month old daughters.

No secrets really, just a mild OCD for tuning. There's one thing I did regarding the headstuds/nuts but I don't want to say here bc I don't want someone messing up their engine then saying it was my advice. Lol

Black51

^^^Oh don't worry, I promise I won't blame you on anything! (unless the engine breaks)

jmj951

Ideally, we need a solution that fits within the cost of an original replacement alternator, so that this upgrade is 'cost neutral' for someone that needs to replace a bad alternator. I've done a little research, and I don't think it's practical. If an 'original' style replacement alternator can be found at a reputable auto parts store as low as $164 (Napa - potentially cheaper at less reputable stores), and the smaller Nissan alternator can be found (new/rebuilt) in the low $100's, then we only have about $50 to play with. This needs to cover the cost of the pulley, wiring, and bracket modification. Wiring mods are just about free, especially for folks that already have these connectors laying around. The pulley was only $10, but let's assume it has to be shipped for most people and now it's around $18. That leaves $32 for either of the following options:
1) Mount modification, plus the cost of the shorter belt. Would require a shipping exchange of original mount for a modified mount. After the mount shipping and the belt, there's nothing left for the cost of physically modifying the mount.
2) Piggy-back mount: between the original mount and the new style alternator, moving the alternator further out to compensate for the smaller size, and therefore allowing the use of the stock belt.

I like option two because it drastically simplifies the installation process, and it allows for returning to an original style alternator, but I'm pretty sure that even a small piggy-back bracket couldn't be done for $32 (commercially). Given that it only saves a few pounds to convert to the new alternator (and you'll lose most of that savings by adding an adapter bracket), the only rational excuse for doing this project is to make room for a larger turbo - with that rationale, someone could charge quite a bit more for this bracket - and if that's the case, then the owner is going for an extreme build anyway and the solution might as well be a full custom bracket to replace the original alternator mount. There is no advantage and a lot of headache for the vast majority of 951 owners. This project is a no-go except for the big-turbo installers (and anyone else whose curiosity is just killing them enough to make it work no matter the cost).

Dare

I’d say your reasoning is pretty sound. In fact, the cost point for the Quest alternator depends on your ability to return the Porsche alternator as a core. If the place you’re buying it from demands a like core in return, you’re out the ~$60-100 core charge.

Now if you rebuild the alternator yourself, as I’m doing, and forgo the custom bracket, the cost comes down quite a bit. My final cost should be around $96, and would be about $10 lower if I used a cheaper belt. But of course that’s not turnkey.

If someone was to look into creating an adapter bracket, I’d suggest looking at the alternator from an Infinity I30 (Hitachi LR1125-702B). You’d have to mount it upside down because of the position of the mounting tabs, but its higher capacity (125A) and it comes with a 6-rib pulley.

Well if you go my route it won’t cost a lot, but you will need a certain sense of adventure.

CPR

CEP already makes a custom Alternator Bracket for use with a smaller (albeit higher output) alternator.

Contact Dave for more details.

Fluidplay

Is it back together? How did it turn out?

eniac

As stated, I'm not trying to sell anything. I posted this thread originally to help anyone who was having the same multiple issues with the poor design of the stock alternator. The only cost to me was buying the new alternator and a cheap belt which was less expensive than a stock unit. For many reasons I am overpleased with the results. The main goal was to show it could be done easily and cost effectively if doing it yourself.

If your 100% satisfied with the stock alternator, plastic cover, and cooling tube then there is no reason not to keep that all as is. If not, this is an option that can be done in one day for the price of a new alternator and a belt. Its cost effective if you DIY. If you pay someone else to do the work, then like anything else on these cars, cost effective goes right out the window.





Smilies

Dare

By request, here’s an update on my alternator project. After some fine tuning the alternator is on the stock bracket and fits pretty well. Best I can measure the pulleys are aligned to within a couple of mm (around 1/4 groove width). I had to replace the top mounting bolt with a longer one—140mm would have been ideal but the store near me only had 150mm so I went with that.

Here you can see the notch I cut out of the top front mounting tab. I did this with a hacksaw and a dremel with a cut-off wheel. Again, around 7mm is all that is needed to get the pulleys to line up.
On the bottom I’m using a tensioning bracket I pulled off of a mid-90s Volvo. It came with a built-in tension adjuster, but there was no way to make that work in this application so I removed it. Also had to drill out the hole at the end to accept an M10 bolt.
I was pretty happy with the setup until I started looking for a belt to fit. Since I’m doing an A/C delete, the tension adjustment will have to be done entirely with the new bracket. Well, as luck would have it, the range of motion on the new bracket falls right between two standard belt sizes. :-( The larger of the two belts (34”, Dayco 5060340, NAPA 25060340) wont tension without switching to a longer bracket. I could do this, but then the top of the alternator would start encroaching on the turbo j-boot, which I want to avoid. Since there are a lot of options when it comes to alternator brackets (both in the junk yard and at the store), this might be the best approach for someone with an N/A.

The smaller belt size (33.5”, Dayco 5060335, NAPA 25060338) is too small to fit over the lip of the pulley with the alternator swung all the way down. If you can get the belt on, however, it tensions up nicely within the range of the bracket. Part of the problem was the flanging on the alternator tab, which hit the lower mount point on the stock bracket. A little more work with the dremel solved that problem.
I was so close at this point, however I needed just 1-2 mm more to be able to get the smaller belt over the lip of the pulley. The hang up this time was the boss for one of the screws that holds the alternator together, which was hitting the center part of the stock mount (see the third picture above). The simple approach would have been to grind the Porsche mount at the point where the boss touches. But I figured I got this far without altering the Porsche mount (and even a used one costs more than what I paid for the alternator!) so out came the dremel again.
With that I can just get the smaller belt on with the alternator swung all the way down, and it tensions up nicely.
All-in-all, not a hard project, but a lot more grinding than I’d hoped for. To be fair though, the added complexity came from trying to do an A/C delete while simultaneously keeping the stock bracket and making room for a larger turbo. Eliminate any one of these requirements and all you’d have to do is grind the top mounting tab and you’d be done.

I uploaded a number of other pictures to my photo album for those who are interested.

jmj951

Can you put a fully assembled MAF intake on that and still clear the alternator?

Fluidplay

Thanks for the follow up Jay...I'm waiting for the pully to come in from AHW this week to finish out this project. I'm keeping the A/C so hopefully won't need to grind as much as you did.

Dare

Unclear. I think so, but I haven't tested it yet. In fact, to start with I'll be keeping the airbox and using a larger J-boot.

Here's a pic head on into the turbo inlet:

Dare

It will be interesting to see how that works out. I have a theory that there's enough range in the stock tensioner that you can still use a standard sized belt.

Fluidplay

I'm hoping that's the case. The new alt. is considerably smaller in diameter, although the mounting point is only .250 difference shorter.