View Full Version : STS engine into SLS

04-28-10, 08:16 PM
What will happen if an engine out of an STS is installed into a 1998 SLS. My friends head gasket went out on his engine and he is adament on installing an STS engine due to costs. I tried to steer him away due to the performance loss but that doesn't seem to be one of his concerns. Are there any other issues with this swap? Has anyone else done this swap and what were the results?

04-28-10, 09:53 PM
IF the engines are the same year there should be no real problems. With different years, then sensors, connectors, and mounts/bolt patterns/exhaust systems can be a bugaboo. I assume he intends to keep the SLS 3.11:1 final drive (transmission unit).

The STS engine is tuned for running a few hundred rpm higher than the SLS due to the different final drive ratios, so the torque curve will be off a bit, BUT if he sends the PCM to Wester's Garage and tells them what he's done, for $500 they'll remove the speed limiter and maybe tweak the timing.

04-28-10, 10:21 PM
Exact same thread going on in the Seville forum, though I don't think it answers your question.