87 Vs 89 Vs 93 Stock And Tuned Results

uh6tdrvr · October 13, 2009

i was wondering if anyone has done any long term test with different fuel octanes. I know the engine in stock form will adjust (pull timing) to different grades, i was just wondering how much.

I've got a G8 with the 6.0 and its a really noticable difference perfomance with 87 vs 93. The owners manual say you can run 87 reccommending premium for maximumn performance. As far a mileage, i dont seem to notica a difference but im kinda checking it now(working on multiple tanks from the same station).

Now as far as my truck goes, the SOTP differance isnt alot but i can tell some especially from a cruise to WOT. Right now im trying to see if my mileage changes.

Tunner smart guys, is there a difference between the E85 engines and the non E85 ones? I know they say the 5.3 makes more HP on E85, does it do the same with premium? Will the non E85 addjust for the same parameters????

Now as far as the fuel differences, im sure their isnt a HUGE difference between the different fuel grades, i was just wondering if anyone had done any long term testing.

FACTUAL IMPUTS PLEASE, eveyone has opinions.

uh6tdrvr · October 14, 2009

Nobody?

FadedSierra · October 27, 2009

Nobody?

As far as mileage and long term affects of octane, I can tell you neither. But I definitely do agree with you about using 93 vs 87. It's one of those things that only the person who drives the vehicle daily can notice but yeah, I do. I've heard that E85 runs the 5.3L with more power too, where can find that info? I don't know if I missed it someone on the website or not but I can't find it anywhere?

uh6tdrvr · October 28, 2009

I have read before that guys that run E85 and have their trucks tuned JUST for it like it and make good power BUT it needs to be tuned for it. I ran it in my 02 suburban and it ran good, ehaust smelled like popcorn...kinda but the mileage wasnt enough to keep on running it plus i had to go out of my way to get to station that sold it for less...like 55 cents a gallon which almost make me brake even.

In both my G8 GT and my silvy with the non E85 5.3 i can tell a difference in the way it runs (doesnt fell as held back) when i run 93 so i am really curious to see how it runs with a 93 tune. My problem right now is that i have to get to a tunner since i have the 6 speed and the tcm in in the transmission.

empirezclub · November 5, 2009

Maybe this helps, maybe not. I have a 07 silverado with the 4.8. I know you wanted info for the 5.3. I had it dyno tuned by Dyna Chip here in AZ. Just taking out the speed limiter and putting it on the dyno it showed 254.98hp. The guy tuned it for 87 and it pulled 289 hp. not bad for a truck rated at 295hp at the flywheel in my opinion. He also tuned it for 91 octane and it pulled 302hp but I had him just leave the 289 hp tune! On to mileage, my DIC said 15.3 when I got there and since the tune the DIC says anywhere from 16.9-17.1 on 30% city and 70% highway driving. Because the truck is so responsive I drive it a little harder in town but on the highway it doesn't kick down to 3rd as often so I can push the gas and it goes without raising the revs like it did when it needed to shift to 3rd gear to accelerate 2 mph! I would think the results would be even better on a 5.3! Hope this helps.

Stevens03 · November 5, 2009

More power, small mileage increase in my 6.0 running 91 over 87. I've tested it for a month back/forth to work (30miles round trip) and saw a little gain in mileage running 91 or better over the 87. The power is better too obviously. For the price difference, I'm not sure the mileage increase for me pays for itself, so I run 89.