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Discussion Starter · #1 · (Edited)
1.5 sohc to 1.5 dohc swap using stock sohc ecu and wires.

OK, well I wanted to post this because no one really supports this swap and the info is hard to find. In fact while i was doing this swap, i didnt find anything that would tell me what to expect. So this is all based on my experience with the swap i just finished.

We will start with why i did it. Many people say that the swap is not worth it and a waste of time and money. It is true that the swap will only give you a gain of about 10-12 hp, and with the same amount of money you spend on this swap could have went towards a beta swap. I did this because of a few reasons:

1. I picked up a 1997 accent se for $350. Its a 1.5 sohc 5sp manual, and the body is in pretty good condition (plus its red compared to my salmon/pink accent i drive now). The motor was blown, but the the cars deffinately worth it. I had a 97 gt as my first hyundai, and this one is one
step down from it. Its got the wiper out back, nice black interior and now the gt motor mated to the 5sp tranny. :)

2. I had the motor already in storage from a 1997 accent gt with 97,000 (so no money spent on purchasing the motor). I knew the motor was in good shape since my gt was my baby till i wrecked her. :mad:

3. There were no beta's at my local pick-n-pull and I didn't want to waste time hunting one down (I'll do that later when i have more money).

OK so on to the swap. This swap is easy and could be done in a day or on a weekend.

Things needed for swap.

1. dohc alpha engine.

2. dohc power steering pump, power steering reservoir and power steering lines from steering rack to engine. The sohc one will not work, its mounted to the back of engine on sohc, and dohc is mounted one the front of engine.

3. dohc passenger side motor mount.

4. dohc down pipe from header down, the sohc is smaller. You will have to cut or change your exhaust at this point. I cut the sohc's exhaust after the flex pipe at a point where it would match up with the dohc pipe I had.

5. Electrical supplies. You will have to cut and add length to a few wires. They go from the injector harness to the block, and on the different motors they mount in different locations. How you choose to do this is on you, just make sure you have the stuff you need on hand.

6. DOHC ECM (computer) been running it on the sohc computer and was wondering why it didn't feel like it had the power it should, put in the dohc computer and man it flys now. Plus the 7,000 rpm cut off is much better than 6,500.

7. Many need to swap to dohc evap canister when using dohc computer to get CEL off. Will post when I fix.

Anyone interested in a motor swap should know the basics of whats involved, so just remove the engine as you would. While its out, replace the power steering lines from rack to reservoir. Put in new engine. Extend the wires, you will know when you get to them. They go from the injector harness towards the passenger side of engine. Theres 7 or 8 wires connected together to make two bundles. Using the sohc wires, they would bolt to the side of engine, but on dohc they bolt to the back of engine on intake manifold. Also water temp sensor wires had to be extended to reach opposite side of engine. They are the 3 wires that go to the sensor on the thermosat housing on the front of the sohc, the go on the passenger side of engine on dohc.

Put on the dohc motor mount, the sohc one will not work. Replace exhuast with dohc down pipe. How you do this part is on you.
Also, with my car I had to mess with the throttle cable. It had to be moved over a bit to work properly (was stuck open a tad causing high idle and revs).

Thats about it. It was a very simple swap, but the lack of info made it difficult for me. I did not realize that the power steering pump was different untill the day when I went to put the motor in. Lucky for me, there was a gt in the junk yard. :)

I will post pics of engine and the wires you need to mess with.
And I can say its got more pep in it than the sohc.
 

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GregsterGSi said:
Just put the DOHC head on the SOHC block...
It might not be that easy depending on the combustion chamber difference between the heads could mess up your compression ratio if you put a DOHC head on a SOHC 4g63 motor (different motor just being used for illustration purposes) takes the compression from 8.5:1 to 13.3:1 and you'd have 16 bent valves....
 

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berserko said:
It might not be that easy depending on the combustion chamber difference between the heads could mess up your compression ratio if you put a DOHC head on a SOHC 4g63 motor (different motor just being used for illustration purposes) takes the compression from 8.5:1 to 13.3:1 and you'd have 16 bent valves....
The head will bolt onto the 1.5l Sohc block no problem. I've seen it done around here no problem.
 

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ASperilla said:
Hmmmm 1st time i have heard of this since i have been on HP.com....
me too!! :confused:
 

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I also heard of the swap!
When we finish the talking about swaping the head from sohc to dohc i think this thread deserves cleaning and a sticky in Hybrid section :rolleyes:
 

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JAh im with you on that BUT generally Dohc = Beta Sohc = Alpha.

Then reason why most people dont drop the Beta onto the aplha Gear bOx is cos the Alpha is Weaker and cannot stand up to the Extra power apparently. Personally i know of this one instance where these Proffesional street racers/drag racer/stock car racers did a beta motor onto a Alpha G Box. So i think They Over Abused the Box. so that actually doesnt give us any insight on the Relieabilty of the Beta engine one the Alpha box
 

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The DOHC swap into the SOHC block sipmly ain't gonna happen. Different water/oil lines. Just forget about it or start drilling exterior lines and weld the original ones.. too risky
 
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