The question that was originally asked here is: Is an Orion 89/90 spec normally aspirated EFI head the same as FRST EFI head. The answer is YES
Originally Posted by XR2
Originally Posted by Rick
yes they are. Nothing wrong with using the escort head either.
No they're not! They've come with a different height. Orion EFI should be a little bit higher than FRST head, so you'll get lower compression which is better for higher boost
But make sure ignition and cam timing is set to the right parameters!
EFI heads came with the injector cut outs on the inlet valves, MFI heads didn't have these!
Sorry mate but your wrong
The lower compression on the turbos is achieved with different pistons