I bought my car a year ago. its a 88 gtu, but I dont think that it has an s4 engine. My boy also has a 88 but its a gxl and our engines do not look the same. Mine has block of plates in places that his doesnt. Is there any possible chance someone can post a pik of a 88 gtu engine. If not ill take a pic once it stops snowing and you guys let me know what you think. thanks.

 

This should help you out pretty well, to determine if your engine is S4 or S5.