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Discussion Starter · #1 ·
In the process of installing a 4bt in my 87 military hmmwv

Purchased what was suppose to be a Remy 22si 24v Alternator however when it arrived it was not a 22si alternator but instead a 28si

I honestly don't know much in regards to alternators and can see this one is not brushless like the 22si and it's quite large and would have to relocate my oil filter along with create a longer attachment piece for the bottom. However wanted to see if there were any downsides to just using this Remy 28si or if it would be better to sell this and get a 22si instead?

Also, is the 22si smaller than the 28si in which case wouldn't have to waste money relocating oil filter? Also, is it better in an off road vehicle to use the brushless 22si or does this not really matter?

Basically, just trying to find out if should keep this one or if it would be better to get the 22si that I was originally trying to get.

Thank You
 

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I have never heard of a brushless 22si Delco alternator. Back in the 80's & 90's I repaired quite a few of the 22si's. So what is the necessity of having a brushless alternator? Any alternator will maintain the battery. The standard 22si was available in both 12 and 24 volt versions. In some cases the only difference was the voltage regulator and the output amp rating. As an example: 12 volts at 120 amps; install the 24 volt regulator and you get 24v at 60 amps.

This may be of interest to you: Alternators by Model Family | Delco Remy

Also, there were aftermarket kits for the 22si alternators to increase the amperage in 12 volt versions. I do not remember the ratings. Why not install one of these kits with a 24 volt regulator? What alternator came on your 4BT engine?
 

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Hadn't run into the 28si before but it is one of their new series of alternators with the internal fans. Looks basically identical to the 24si. The 21si and 22si were the older style versions with external fan. One question would be which mount style did you get? That one comes in a pad mount, J180 short hinge, and J180 long hinge. All the 24V models are 110 AMP. Here's the spec sheet on those. https://www.delcoremy.com/getmedia/...elco-28SI-Single-Page-Brochure-12-14.pdf.aspx The brushless models in the Delco line would be the 23si, and the 33si -55si models.
 

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Discussion Starter · #4 ·
The 28si was so big that it hits the oil filter and was thinking maybe the 22si would be smaller and not hit the oil filter but could just change out the oil filter cover and locate it somewhere else. From just looking at the picture of the 22si (first picture) vs the 28si (second picture) I wasn't sure if maybe the 22si would had been better since it appeared to me as though sand and dust wouldn't be able to enter it like it would on the 28si but I have no idea if this is even an issue when it comes to alternators. Also, I may be using these terms wrong and apologize, don't know much about alternators and thought that the way the first one appear sealed was considered brushless and guessing maybe that's incorrect. I was trying to purchase the 22si (first picture) and got sent the 28si (second picture) so just wanted to double check that it was fine or if it would be better to get that sealed looking style like the first image. Also, since the 28si does hit the oil filter would replacing the cover with a piece like this 3rd image be what I need to relocate the oil filter somewhere else? I currently have the cover where the oil filter comes out perpendicular to the motor and the 28si is so long that it's hitting it.

Again, thank you for the help and sorry for making things confusing since trying to learn the terminology as I go and seem to be butchering some things. This is first motor swap have ever done and first diesel I have ever owned so basically trying to learn all this at an accelerated pace. I just figured if I can perform surgery on a human than I can surely perform a motor swap on a vehicle however starting to believe the vehicle is the harder one at this point and have much more respect for people who do this.

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You should also keep in mind that there was more than just one mounting frame style per series. There were closed frame units, the ones you refer to as sealed, in most si series alternators. Maritime, hazardous industrial location installations, and some agricultural installs used them. The down side to sealed is that the life expectancy was reduced because solid state devices used internally have a higher failure rate due to heat.
 

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None of that series alternators are going to be small. The 28si measures 9.27" nose to tail and height is either 7.79" or 8.50" in the mounting holes. A 23si is 9.75" nose to tail and height is 7.79" so it is no smaller. The 22si wouldn't be in the running as it only comes in 12V. The 23si comes in 12V or 24V version with the open fan like the 22si. After these models they just get a whole lot bigger. These are heavy duty alternators designed for medium duty to heavy duty trucks and industrial equipment.
 
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