I may have come across my next project vehicle, a 98' saturn sl1 5spd. It needs engine work and I am wondering how much trouble it is to convert a SOHC to a DOHC engine, or if it can be done at all. I am assuming the bottom end is the same and the cylinder head changes. Will a 98' run into a bunch of extra problems being OBD-II?
I think- note the word think- its kinda like a Neon. Get the engine, plug it in the same holes where the old engine was, find the ecu thats compatible with the engine you now have, and drive.
It's not too bad. I did it on my old car. the block is the same, so it drops right in. You'll want the DOHC trans as well.
Yes, very easy if you're pulling the engine already. All mounting points are the same, the block is the same (slightly lower-compression pistons for the SOHC), all sensors are the same, just need a different ECU or a reflash.
Kevin is right though, a single-cam trans mated to a twin-cam motor (that's not forced induction) makes for a car annoyingly kept out of it's power band all the time.
The OBD-I/OBD-II thing isn't a huge problem, but try to find a head from an OBD-II car, it'll make your life easier.
Have fun with your extra 24 horsepower and 1000 rpms!
Swapping the whole thing for a DOHC is pretty easy. you will want to swap the whole engine, not just the heads. As it was said in 98 SOHC ran lower compression pistons.
The best blocks are the later 00-02 DOHC as the bottom of the block had a brace. The best heads seem to be the from around the middle '96-'99. I'm not certain on the year, you'd want to check a Saturn forum.
It may not be worth doing. You can normally find a clean DOHC cheaper than the parts + an SL1 runs. Plus with a SL2 you get some other goodies, like a rear anti-roll bar. Overall I tend to steer people to go for a SX2 car.
I did some reading around last night and got an update from the seller this morning. The car looks to be a 98' SL, base model. Would that make finding the correct computer difficult?
Also I read that the SOHC heads have issues with cracking, which I am assuming happened on this car. The owner has the cylinder head removed, but from what I am reading it is usually cheaper to yank the entire engine and replace it.
What would be the best year to replace it with? There seem to be three generations of SOHC/DOHC engines -94, 95-98, and 99+.
In reply to Nitroracer:
95-98 engine.
Yank and replace is my vote. But if you haven't bought it, it may be worth looking at another make or starting with a DOHC.
Just get the computer with the DOHC. Later 99+ models are a pain to swap as the computer stuff changed a bit. They have a funky body control module that talk to the ECM. But you are talking about a far easier year.
the best build is 96-98 DOHC head/intake/ECM with 00-02 block. There are some fine points on wiring etc. Check out sixthsphere.com for more.
At this point the S series is at the bottom of its depreciation curve. Just about any car, except maybe the last few years of its 1991-2002 run, are going to be Challenge priced, regardless of body style, engine, and options.
All of the motors use the same block, just a different head. Parts are common and cheap enough that it's easier to just swap to a DOHC motor. Pick up a DOHC parts car if you can and swap in its more powerful engine, better seats, rear sway bar (SOHC cars don't have one)... Or just buy a DOHC car that works and save yourself the trouble.
The only reason I'd buy a SOHC car at this point is if I was mainly interested in fuel economy.
The handling differences are fairly drastic too e.g. the SC/SL 1 doesn't have a rear sway bar...
You'll need to log in to post.
