Simplify the following text for a Grade 9 native English-speaking person.
Original: Starting in 1997 , IRL cars were powered by 4.0 L V8 , methanol burning , production-based , normally-aspirated engines , produced by Oldsmobile ( under the Aurora label ) and Nissan ( badged as Infiniti ) .
Simplified: Starting in 1997 , IRL cars were powered by 4.0 L V8 , methanol burning engines . They were production-based and normally-aspirated engines .