Received my SCT tuner from 5Star yesterday, was reading the instructions and just wanting to be sure that if I install the 87 octane tune, that is the only fuel I can run with that tune installed? If I were to put say 89 or higher in it could damage the engine? I am new to this and just wanting to be sure.
I'll preface my answer by saying a quick call to 5star will confirm the answer for ya, but here's my .02 worth; Running higher octane won't hurt a thing, but if you want to burn premium, by all means run the 91 (Or 92, whatever you have), tune. You'll be glad you did! You did get a premium gas tune included as well, didn't you??
No need to call 5star. running a higher octane than a vehicle or tune is designated for is perfectly fine. The higher octane fuels prevent early detonation in high compression situations. If the engine is tuned for 87, it will not compress the fuel mixture as much before combustion as compared to an engine tuned for 93 octane.
A higher compression tune creates more power from the fuel mixture, but if you do not have a high enough octane level the fuel with self ignite under the higher compression (prematurely) and cause the engine timing to get thrown off (also known as knocking). If that happens, damage could happen....but lucky most current vehicles include our truck, has 'knock sensors'. If the 'knock sensor' is triggers, the truck automatically delays the timing of the valves to reduce the compression cycle.
I'm not 100% how the knock sensors behave due to a tune, as the program writter could change the behavior.
To make a long story much shorter.....you are ok with running a higher octane than needed.