Swapping a 1999 Saturn SOHC engine into a 1997...Can it be done?
#11
03-29-2024, 02:55 AM
As you said, anything can be done. When there's a will there's a way.
But at minimum put this SOHC into a 1997 s car that was a DOHC, you would indeed need
1) 1997 SOHC PCM with automatic transmission
2); Likely The 1997 SOHC under hood wiring harness to make this less painful
3) The air pump didn't come in until after 97 on the DOHC, so if the new engine comes with the air pump attached, he will need to leave it disconnected and plug the lines as I don't believe there is a passage in the block but that exists in the third generation engines
4) mating a 97 SOHC motor to his existing mp8 transmission for the DOHC will result in an interesting shift in the shift points. I expect the TCM to throw constant "incorrect gear ratio" errors since it is expecting to see the gear ratios associated with an MP7 from an SOHC automatic. The cross connection of SOHC and DOHC engines with DOHC and SOHC transmissions, respectively has been done. I believe the vehicles are drivable but I cannot tell you how differently they would drive. The information is on the net but you'll have to dig. And I hate to say this but it was probably on Saturnfans. You can sign up at sixthsphere.com's website or preferably their Facebook group as the site itself does not get much attention. They've basically moved the discussions to the Facebook group. These folks were the people creating their own turbo installations, modifiying anything you could on the car. I have to believe one of them would have done the swap you are trying to do although most people swap from an SOHC to a DOHC for obvious reasons.
5); if it is in early enough 99, then it would need the 97 style SOHC exhaust manifold which I believe has different number of mounting studs and locations than the 97 DOHC equivalent.
6) Believe the intake manifold between SOHC and DOHC is different in general. So he would need an SOHC 97 intake manifold.
7); I believe the fuel rail setup would have to be from a 99 SOHC because the 97 DOHC and 97's in general had a fuel return line to the tank that the 99 and up did not. Also, different injectors in all likelihood.
8) if it is an early enough 99 s o h c, it should still have the horizontal throttle body and throttle cable to match the 97 car. If not and the 99 engine has the throttle body mounted vertically, there's another set of issues to solve.
That's off the top of my head.
If the person you are selling this to is made aware of of this information prior to purchase, knowing how much work will be involved along with the cost to make this engine run properly in the 97 that's one thing.
If the engine is being portrayed as a bolt in and drive, save both of you a lot of trouble and find another buyer or use it in your vehicle..
Once you make that decision, we can figure out whether or not putting it in the 2002 makes sense.
But at minimum put this SOHC into a 1997 s car that was a DOHC, you would indeed need
1) 1997 SOHC PCM with automatic transmission
2); Likely The 1997 SOHC under hood wiring harness to make this less painful
3) The air pump didn't come in until after 97 on the DOHC, so if the new engine comes with the air pump attached, he will need to leave it disconnected and plug the lines as I don't believe there is a passage in the block but that exists in the third generation engines
4) mating a 97 SOHC motor to his existing mp8 transmission for the DOHC will result in an interesting shift in the shift points. I expect the TCM to throw constant "incorrect gear ratio" errors since it is expecting to see the gear ratios associated with an MP7 from an SOHC automatic. The cross connection of SOHC and DOHC engines with DOHC and SOHC transmissions, respectively has been done. I believe the vehicles are drivable but I cannot tell you how differently they would drive. The information is on the net but you'll have to dig. And I hate to say this but it was probably on Saturnfans. You can sign up at sixthsphere.com's website or preferably their Facebook group as the site itself does not get much attention. They've basically moved the discussions to the Facebook group. These folks were the people creating their own turbo installations, modifiying anything you could on the car. I have to believe one of them would have done the swap you are trying to do although most people swap from an SOHC to a DOHC for obvious reasons.
5); if it is in early enough 99, then it would need the 97 style SOHC exhaust manifold which I believe has different number of mounting studs and locations than the 97 DOHC equivalent.
6) Believe the intake manifold between SOHC and DOHC is different in general. So he would need an SOHC 97 intake manifold.
7); I believe the fuel rail setup would have to be from a 99 SOHC because the 97 DOHC and 97's in general had a fuel return line to the tank that the 99 and up did not. Also, different injectors in all likelihood.
8) if it is an early enough 99 s o h c, it should still have the horizontal throttle body and throttle cable to match the 97 car. If not and the 99 engine has the throttle body mounted vertically, there's another set of issues to solve.
That's off the top of my head.
If the person you are selling this to is made aware of of this information prior to purchase, knowing how much work will be involved along with the cost to make this engine run properly in the 97 that's one thing.
If the engine is being portrayed as a bolt in and drive, save both of you a lot of trouble and find another buyer or use it in your vehicle..
Once you make that decision, we can figure out whether or not putting it in the 2002 makes sense.
so what are you thoughts of putting it in my 2002? I know there is a slight difference in mounting positions for the knick sensor but I think it's close enough I don't even need to extend the wiring.
I would need the 1999 exhaust manifold (which i have) that manifold looks like it would have better flow characteristics due to the port shape and size. I think it is a bit larger than the oem 2002 one due to the added holes in the head under the ports for the air injection pump. To avoid codes, i am thinking of getting another 2002 exhasut manifold, cutting off the cat, and welding the appropriate flanges on it to bolt it to the 99 manifold and to a down pipe. A machinist at work can prob make me mounting blocks that could be welded to the pipe above the cat to mount the air pump pipe.
may need to have custom down pipe made but there is an exhaust shop within walking distance from my house
#14
03-30-2024, 01:39 AM
Haha! I know what you mean and I get that a lot. I work nights and don't crash out until quite late. My friends used to call me at 10AM and leave messages saying "what the heck are you doing sleeping this late, it's 10AM." 10had to remind them over and over that I got out if work at 2, 3, 4 5, or 6AM depending on my schedule. They never learned.
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