Most of my experience is with calibrating efi cars rather than gen2 Hemi's specifically. That being said I'll throw in my .02.

On naturally aspirated combinations I start with a relatively conservative timing curve and first dial in target wot air fuel ratio.

Once that is done I'll put a few more degrees in and see if power increases (along with watching knock sensor output on the stuff I'm working with).

As long as it isn't getting knock I'll continue to add a degree at a time as long as power is increasing, noting if this is making the same result throughout the rpm range or varying at different rpm ranges.

I've at times been surprised by how much timing something wants to make max power and also, how little an engine required to make max power.

As far as octane playing into this is concerned, I've only seen higher octane add power if as I was increasing timing and seeing power gains I ran into excessive knock/knock sensor output before I reached a -peak- as far as total timing and horsepower is concerned.

I feel many say "race fuel has a slower burn rate". Truth is many factors influence burn rate but most gasolines burn rate is very similar. If anything, some race fuel is tailored to a faster burn rate as there simply isn't enough time for complete combustion at 9000+++ rpm as there is at 5000 rpm.

So, moving on, look at the energy value of the fuel, or BTU's per lb. Regular pump fuel is slightly higher BTU/lb than most race fuel so if the added octane isn't needed for your combination you will generally get slightly less output from using it.

Exception is E85 which has a much lower energy value but also a much lower stoich value which more than compensates for it. (as in you are burning much more of it)


Your engine at 11.5-1, hemi, aluminum head. I would be surprised if you were leaving much on the table with pump 93. I wouldn't expect it to like more than 32-33deg no matter what fuel.

That being said, only way to know is to test it. Run it back to back at the track or dyno. I would probably try something like 260 GT, 100 octane oxygenated if you are willing to spend the money on race fuel, rather than 110, IMO.