Long term owners of BlackBear Autocal tunes.

[Drok]

Yes! Burn the fuel you want the motor tuned to.

10/4. Ill have to burn through this tank and put it back to 91/93. I was being cheap last week and used 87 lol

 

[Joseph Garcia]

For future reference, is there a noticeable difference between an 87 vs. 93 octane tune?

I work from home, don't commute any more, and used to have turbo cars that all required 93, so I don't care about paying a little bit extra for 93 octane at every fill-up.

Thanks.

Here is an example that I can share with you for your question. The 07 Yukon XL Denali with the 6.2L motor is marketed to run 87 octane (though 91 octane is 'recommended'), and the stated HP for the motor is 380. The 07 Escalade with the same 6.2 motor is marketed to run 91 octane, and the stated HP for the motor is 405. According to Justin from BBP, the two motors are identical, except that one is factory tuned to run 87 octane and the other is factory tuned to run 91 octane.

 

[George B]

Here is an example that I can share with you for your question. The 07 Yukon XL Denali with the 6.2L motor is marketed to run 87 octane (though 91 octane is 'recommended'), and the stated HP for the motor is 380. The 07 Escalade with the same 6.2 motor is marketed to run 91 octane, and the stated HP for the motor is 405. According to Justin from BBP, the two motors are identical, except that one is factory tuned to run 87 octane and the other is factory tuned to run 91 octane.

So, what if you run 87 in a truck tuned for 91? Subpar performance..

 

[Joseph Garcia]

So, what if you run 87 in a truck tuned for 91? Subpar performance..

That would be my thought. It does not necessarily mean bad performance, however.

 

[George B]

That would be my thought. It does not necessarily mean bad performance, however.

I tend to overthink things and then get analysis-paralysis.

 

[Drok]

I tend to overthink things and then get analysis-paralysis.

Ha yeah me too sometimes

 

[swathdiver]

So, what if you run 87 in a truck tuned for 91? Subpar performance..

There will be a knockin' and a pingin' going on. Do it for too long and the pistons and or rings may break up in protest.

 

[BlackBearPerf]

Yes! Burn the fuel you want the motor tuned to.

Exactly.

 

[George B]

There will be a knockin' and a pingin' going on. Do it for too long and the pistons and or rings may break up in protest.

I know I am asking dumb questions. And, I understand octane and performance and how preignition plays a roll. I guess I am wondering if the PCM would pull timing and detune due to the lower octane or if it would let the engine self destruct.

I wouldn’t want to run on 87 and my truck runs like crap on it stock anyway so I run on the 88/E15, E85 or whatever is available in a mid grade fuel like 89/E10.

Hypothetically, If I tuned on 89/E10 and then went to E85 the truck should still perform well.

 

[Peacock]

Engine Masters did a dyno flog on octane and if it helped your motor run better, they did a base line pull with the cheap stuff, then 91 octane and then to race gas, E85
They ran an LS3 on engine dyno with 87, 91 pump gas, 110 and 113 race gas and E85 - adjusting timing and AFR for max power/torque.

Results can obviously vary for different engines with different compression ratios (and boost), but in this case, every single fuel except E85 resulted in basically same power and torque. Makes these discussions where people swear on running 93 - let's say - interesting.
I believe at the end they threw more timing in it from 29 total to 34, still had the race gas in it, and it actually lost one horsepower as compared to the 87 octane and 29 degrees timing. The EGT's were worse too, pretty interesting episode.
Now if you had an engine that was 14-1 compression and built to run on race gas of course it wouldn't last long going down in octane rating, it would eat itself up from detonation.
I have the 91-93 tune on mine, I assume they throw a few degrees timing into it with a different fuel curve to work together.