Theyre not the same engine though. There's the generation 1 High Output GT engine, and what I think was a 1.8 or maybe a 1.9L regular scort engine. In 1991, the regular scort got a 1.9L Cosworth, but the GTs took a 1.8 DOHC Mazda engine (the same found in the 90 protoge and I think 323 and/or 626s). This is a completely different engine, and the only reason I purchased this car. I loved my 89GT, but I don't trust american made engines to run for high milages without major repair. I got lucky with the 89, and the death of it was cause by the ingnition modulator. I trust Mazda engines to run forever, and really want this 91 GT scort to be my everyday car for another 100,000+ miles. I am just trying to clarify the differing answers I've gotten. I've been told the 1.9L cosworth is an interference and the 1.8 mazda isn't. I've been told that the mazda is and the cosworth isn't. Now you said they both are. I just want to know for sure, and can't find any answers from the manual, repair manuals, dealerships, mechanics or messageboards.