“Bulletproof” 3v Denso Alternator

If you have been around 3v’s very long you probably already know that the stock Motorocraft 6G alternators that come on 2005-Mid Year 2009’s (and other Ford platforms) are garbage. They don’t tolerate RPM’s very well and they can’t be fixed, modified, or improved to last. It’s an inherent design flaw. Even the hot rod “aftermarket” ones have the same fatal flaw, there is no way around it. That’s why Ford switched to the Denso across the board in mid 2009. Some people have gotten “unicorn” Motorcraft 6G’s and made them last, those are the “exceptions to the rule”. The rule is that the 6G fail at a very high rate.

 The bottom line is if you haven’t had to replace your stock alternator yet, you will. And if you have replaced your alternator with another 6G (even a 200A aftermarket one), you will eventually need to replace that one too. Especially if you spin your motor hard.


 -165 amps

 -It come with the “ears” already removed (something you need to do during installation to the stock alternator).

 -Powdercoated pretty black.

 -Your choice of a 6 rib (standard) or 8 rib (if you’re upgrading to 8 rib) clutch pulley.

 –These are $305 with your Phase III kit purchase.

 More Info:

 A little food for thought on big amp alternators. The more amps an alternator puts out the higher up in the RPM range that it needs to be to make those amps. In the real world what this means is that at idle or cruising around town a lot the big alternators are not putting the amps out that you need. You have to spin your motor faster, and therefore the alternator faster to get the power. Think of big alternators like a high RPM naturally aspirated race motor or a small motor with a big turbo. In the low RPM’s and midrange they’re turds. Only once you spin them up hard do they start to make power. Like most things in life and hot rodding, there are tradeoffs. And the trade off with big alternators is that you don’t get all that power when driving normally, which means you’re leaning on the stored energy in your battery. Under certain conditions this can be an issue.

 More food for thought. Most people, us included had never put pen to paper and actually figured out how many amps you need to get “the job done”. The job being different from combo to combo. A naturally aspirated combo making 450hp doesn’t have the same amperage needs that a PD blower application with 750hp. We sat down and added up all of the amp requirements for a PD blown car making big power. This included the largest intercooler water pump available which draws 8x the amps that all of the other intercooler water pumps do, so a worst-case scenario. We also included three fuel pumps, dual heat exchanger fans (which you don’t want on your car) and all of the cars stock amperage needs. We came up with 158amps. And that is assuming that you’re running everything electrical on the car at the same time. Which would be never. So why get a 200A alternator that doesn’t charge well at low RPM when you don’t need that extra amperage. The only situation where you need more than 165A is if you have a massive stereo. You will still have the low RPM charging issue though (unless you get one of the super high dollar “stereo” alternators). It could be argued that in a lot of situations you would be better off with a smaller alternator with a big stereo too.

 You can get Denso alternators as replacements for your current 6G’s from just about anywhere now.

Some things to keep in mind about those:

 They may have a core charge.

  • The max that you can get over the counter is 150A and most are 135A.
  • They are reman alternators built with the cheapest components that can be used.
  • They do not come with a clutched pulley and your 6G one will not swap over.
  • They don’t have the option of a 8 rib pulley.
  • They’re not pretty powdercoated black.
GT450-650HP Electrical/Ignition