I have a 1998 neon with a trashed DOHC. While searching for a replacement engine, I have found lots of SOHC engines with low miles and low prices and have only found a few DOHC engines for big$ and tons of miles. My question is can I simply buy a SOHC engine to replace my blown DOHC. What changes are necessary? Can I use the same computer? Same wiring harness? HELP!

 

Different PCM and maybe a different harness or swap your current sensors onto the SOHC engine.

 

Thanks for the info!!! I would prefer not to change the computer. Will the sensors on my existing 1998 DOHC engine fit all SOHC engines or do I have to get a 1998 SOHC engine?

 

A DOHC PCM on a SOHC engine will cause it to run rich. Get a PCM for the year engine you purchase.

I don't know about the sensors as they have changed throughout the years.

 

you can use the SOHC block as long as your DOHC head is still good.

 

The temp sensor is in a different location and the cam sensor is not the same. As mentioned before you can run the DOHC pcm on the SOHC but it will run pig rich and your mpg will suck. The MAP sensor is different and you will have to change the plug in order to fit it in the one for the SOHC. It will be easier if you can get the engine harness with the new engine.

 

https://dodgeforum.com/forum/1st-gen-neon/79014-dohc-head-on-a-sohc-block.html same concept but reverse order if your head is still good from your DOHC.

 

So if I buy a junkyard sohc engine my dohc head will fit without modification? What happens to the compression ratio? Does it go up or down?

 

The head fits fine. Did you not read the post that DOHCgarrett t3 posted?

 

Yes, I read it however this created more questions than it answered. Most of that discussion was aimed at someone who owns a sohc car and wants to install a dohc head. I have a dohc car and want to replace the bottom end of my engine with a sohc block, pistons, crank, etc. OR to be more specific I am considering buying a sohc engine to replace my dohc that has tons of miles (188,000) and a spun rod bearing. Since the replacement sohc engine has different sensors and requires a different pcm, I thought it may make more sense to use the junkyard sohc bottom end and install my dohc head. This could possibly eliminate the need to use a different pcm thus allowing the use of all my current dohc sensors and wiring harness. Does any of this make sense or should I just jerk the dohc engine and replace it with the junkyard sohc and new pcm??? If I do the head swap, how will the dohc pcm react to the lower compression ratio?