IRP 140 Amp Alternator


Core Charge *

Case Options

Please select this option if you would like to have your alternator Powdercoated.

Desired Powedercoat Color

We use Prismatic Powders to coat our products and have most common colors in stock. If you need a special color please let us know and we will contact you to discuss options if the color is not in stock. Please go to the Prismatic Powders Color Selector and pick a color.

New Alternator Post

This item is sometimes melted or corroded. We have Brand New ones available to ship along with your newly upgraded alternator. (Sometimes these come broken in shipping or are just downright unusable when we receive your core. It is a good idea to replace these)

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The stock FD alternator is rated at 90 amps, which is adequate for stock cars. Our 140 amp upgrade significantly improves the charging system’s capacity. We can upgrade both FD and FC alternators. If you are running aftermarket gauges, stereo, larger fuel pumps, auxiliary lighting, mini battery, etc this is a very worthwhile upgrade.¬†Each alternator starts with a full cleaning and media blasting of the case. The alternator then undergoes a full rebuild. A larger stator with more windings and matching regulator is fitted to increase the amperage. Don’t be fooled by others claiming a higher output. Those units have to be spun much faster to generate the claimed amperage and will cause charging issues at idle. We have tried and tested these units and have found the best balance of output vs rpm.

While we can update S4 and S5 FC Alternators there are some limitations due to the size of the casing. S4 alternators can typically hit around 100amps ~ S5 we can get closer to the 135/140 mark. If you have a S4 RX7 and need more then 100amps we would recommend upgrading to retrofit an S5 or FD alternator.

-Please note that we require your core alternator to perform the rebuild and upgrade. Due to the increased cost of alternator cores, we had to increase the core fee. There is an $200 core fee if you are not supplying us with your alternator first, which is refundable upon receiving a good core. If you select “Sending Core” we will await the arrival of your core, upgrade your alternator and send your alternator back to you. Please send to our shop address located on our ABOUT PAGE. If you send a core after receiving your order we will refund the $200 core fee as long as it is received within 30 days and in good condition. If you do not have a core to supply please call to confirm that we have cores in stock, or an ETA of when we may be expecting more. Turnaround times are only estimates and are not guaranteed if you do not supply us with a core. Refunds are not available on custom items only replacement against material or build related defects within one year.¬†

– An alternator with a cracked case is not acceptable as a core. The most common way this happens is trying to hold the alternator stationary by inserting a screwdriver or other tool through the vanes of the case while removing the pulley nut. The pulley nut must be removed with an impact wrench.

-There will be a $30 fee charged to replace a broken alternator post. The most common way this breaks is improper padding during shipping. We recommend that you remove the post and send it with the alternator but package it with packing material to avoid damage.

Please note: Powder Coating may add 1-2 weeks depending on color choice.

Please contact us for more details.


Additional information

Weight 208 oz
Dimensions 8 × 8 × 8 in

I'll send my core to be built., I do not have a core to send.


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