Just speaking from experience here from reviewing dyno numbers with the tuner after each pull. You could always tell the guys that were running cheap or low octane gas on their 93 octane tune. And from what I read, all publications rate this hemi at "up to 390hp". The owners manual recommends 89 octane. So I would assume that 390 hp claim would be based on using the recommended octane and not 87 where the knock sensor would pull timing. I would be curious to see where you got info from using octane higher that 89, the Dodge pcm would command an increase in timing. Heck, I'll fill up with 93 octane tomorrow if that is the case.

 

The 09 GMC 2500 I drive for work has the 5.3, its clearly a 5.3 as indicated on the emissons sticker, the truck has the 2500 badging and supension, the 6.0 is the vorteck max( I did mess that one up )

 

Just Vmax for short. With just a tune, they can be pretty close in performance to both of us. Just watch out for the Escalade in the Avalanche trim (dont know what its called) with the 6.2. Those can be pretty quick. Nothing a RCSB cant handle though.

 

I don't doubt your experiences with the dyno, I am suggesting that in the case of the 09 Hemi it might be octane sensitive. If you have dynoed the new Hemi and the results don't support this then I stand corrected. I have never seen the 09 Hemi rated as "up to 390HP" or anything less than 390HP but (absolute numbers aside) this statement in of itself suggests some variability and perhaps it is based on Octane? I am sorry, I cannot recall exactly where I read the PCM will increase timing based on Octane but I have in several casual reads. Perhaps next time I will pay more attention to the source and I'll cite it. Now, based on my "seat of the pants Dyno" I do feel a performance increase from 87 to 89 Octane so I run 89 all the time. I have run 91 but can't honestly say I feel a difference from 87 with that. Maybe this is where the tune is going to be required to feel any gains.

 

I think the 09 and up hemi's are rated at 390 with 89 octane in the tank. Lots of companies are doing this now. The new F150 is only rated at like 365 tq or something like that, but when using E85 or a blend, it shoots up to 390tq. The new mustangs are able to use both 87 and premium, where there aren't any gains in premium, but the hp and tq curves are a lot flatter.

 

You speak volumes. Knock sensors are relatively new and not there for performance. They are there for warranty issues. Coupled with the PCM, after detonation occurs, they can instantaneously pull up to 20* of timing to inhibit engine damage. Mainly because gas quality from area to area and it's differentiation, climate changes and such, and other issues having to do with long term end-user maintenace. How else would our manufacturer be able to issue a Lifetime Powertrain Warranty?

 

And I gotta say,

Even though my GRandfather died fighting the japs in WWII, I suppose it's good having a sosial star here.

 

Well I guess now that there are so many fuel efficient cars out there now and engineers are figuring out how to get the mileage they need with these big motors and electronics, we can afford to have another gas guzzler truck out there with us LOL.

 

knock sensors have been around for over 20 years now.....and the pcm has no clue what you put in the tank...89,87 or 93 but your engine will ping inaudible and your knock sensor will pick it up and the pcm will retard the timing until it doesnt here the sound anymore.....the pcm adjust timing based on alot of variables

 

Lol, thanks. I have two uncles that fought in that same war. Glad to be here, you all seem pretty cool.