K Series Transmission Differences

K Series Transmission Differences


It wasn’t so long ago that the i-VTEC K series of engines from Honda was more bleeding edge than cutting edge for most engine swappers and modders. Things have definitely changed recently as the K series continues to push the horsepower bar above what it’s older B series cousins have achieved.

It’s still a much more expensive option than the B series, but the K series continues to push the performance limit for four cylinder small displacement engines. Hard to predict where the all-motor K series application will end up on the very long list of Honda performance engines, but it’s definitely surpassed a lot of expectations.

How To Install a AEM Cold Air Intake on a 2014 Honda Civic SI


We’ve had a lot of transmission related questions, thanks to user Oxbigg on our FAQ – Honda Swap Combinations – What Fits What DIY Guide. Today we’ll be covering the K series transmission differences and how they relate to you in terms of performance or engine swaps.

For the K series transmission, there’s two types of speed sensors which work very differently dependant of sensor design and implementation. There’s a low frequency and high frequency speed sensor, but that’s not where the differences stop. If you are planning a K series engine swap, you’ll need to plan ahead of time to avoid costly mistakes or wrong parts that won’t work together.

K Series Transmission Differences


The Low frequency K series transmission found in the 2002-2004 Acura RSX and 2002-2005 Honda Civic SI will use the Honda part number 78410-S7A-G01. This speed sensor is at the back of your manual K series transmission and the Vehicle Speed Sensor signal is sent to both the ECU as well as the instrument cluster.

Knowing the K series transmission differences will not matter much if you won’t be using the stock instrument cluster, if your swap is intended for another chassis, check our How To Swap K series Guide here.

K series swap guide
K series swap guide

The High frequency K series transmission is in the 2005-2006 Acura RSX as well as the 2006-2007 Honda Civic SI. The Honda part number for this unit is 78410-S7A-G01, and this unit is not only located in front of the transmission housing, but it works completely different as well. This sensor signal is transmitted to the ECU, which in turn translates the input for the speedometer in the RSX or Civic cluster.

This makes Honda K series engine swaps a bit more difficult for the average modder, as you’ll require the right dash and wiring harness as well as ECU if you want to swap it into your RSX or Civic.

How To Service Your RSX IMRC


We’ve received the question of fitting a 2005-2006 K series transmission on a 2002-2004 and the very same frequency limitations will apply. When shopping for a replacement transmission, you must also use caution to avoid mismatching speed input and output systems. These are the things you’ll have to watch out for when learning what K series transmission differences will affect your project.

Want more Honda engine swap information or How To Guides? Check out more below


  1. I am installing a K-24 engine in a 1993 civic im not sure about the transmission. .5 speed is really what I plan to use. My only question s are the wiring harness and going to coil packs I found a K-24 engine at a junk yard with 79,000 miles my plan is to tear down the engine and rebuild it..I started the engine it ran very smooth. .im embarresed to say I bought this engine for 150.00 !! A 200 hp K-24. I was completely shocked. .this is a 5000,00 engine.my plan is to install it in a 1993 civic I found your install post very helpful I am in the process of trying to figure out what kind of computer to install I am changing all the gauges to digital. As far as everything else I understand what all I need..I think I will go back to the yard and get the under the hood engine harness. .I thank u folks for a detailed thread of what will work n what won t. I am leavin my email address and wonder if any of or some of the parts I need if you folks sell them..my first job is to rebuild this engine..I plan to turn the crank turn the rods ring job and have the head done at 1 of the best shops in baton rouge La..I am leaving my email address and thanks guys for info..

    • Hi Paul! sounds like an awesome build and project sir!

      Thank you for the kind words, our guides are here to help people just like you! We’ve edited out your email address, just for your privacy but we have it on file.

      As far as the transmission is concerned, the differences found in this guide won’t matter much especially if you are swapping to electronic gauges. This eliminates a ton of the problems that most people run into when trying to swap a K series.

      The ECU will need to come from a Accord, RSX or EP3 that you prefer to use. Although if you are running a K24, you will most likely want one from the Accord or six speed Accord. Of course you can also opt for a piggy back system or standalone to make things easier.

      Check out some of the other K swap posts below to learn more sir :



      Thank for reading and commenting! Let us know how your K series swap turns out!