Octane on the 5.0 Coyote

[gray owl]

On an episode of engine masters they used gas with octane from 91 to 116. The difference on the dyno was virtually nothing. I believe the engine was an LS3. So i wonder what if any does high octane fuel do for the coyote. If higher octane does not increase performance then why run it.

The fuel that did make a significant power increase was E85.

Would like to hear your thoughts.

 

[Noobz347]

Octane rating is [only] about an additive package that increases resistance to detonation.

There is no advantage to running fuel higher in octane that the engine requires.

 

[gkomo]

Did they change the timing on the engine at all during the tests?

 

[gray owl]

Did they change the timing on the engine at all during the tests?

They took the engine to 29 degrees advanced that was all it would take. The dyno runs on each of the 4 fuels from 91 to 116 showed virtually no difference in engine performance. The thought that higher octane would allow more advance did not play out.

 

[Noobz347]

They took the engine to 29 degrees advanced that was all it would take. The dyno runs on each of the 4 fuels from 91 to 116 showed virtually no difference in engine performance. The thought that higher octane would allow more advance did not play out.

It does but only if there is room for advance.

The modern Coyote V8 is already at 12:1 compression ratio with direct injection maintained by the EEC.

Advancing timing so that the flame front begins [earlier] doesn't achieve the same things. There's no 'swirl' of fuel and gas to mix in the chamber before ignition. Instead, the fuel is injected much closer to the ignition event.

That modern ECU can "sense" all the old tricks and has the final say. This the portion you would have to modify.

You’re not really “sneaking timing into it” like the old days. The ECU knows where the crank and cams are, knows what timing it commanded, and still has the final say. If the calibration doesn’t ask for more timing or load, the computer is just going to correct the slop out of the base adjustment.

 

[gray owl]

It does but only if there is room for advance.

The modern Coyote V8 is already at 12:1 compression ratio with direct injection maintained by the EEC.

Advancing timing so that the flame front begins [earlier] doesn't achieve the same things. There's no 'swirl' of fuel and gas to mix in the chamber before ignition. Instead, the fuel is injected much closer to the ignition event.

That modern ECU can "sense" all the old tricks and has the final say. This the portion you would have to modify.

You’re not really “sneaking timing into it” like the old days. The ECU knows where the crank and cams are, knows what timing it commanded, and still has the final say. If the calibration doesn’t ask for more timing or load, the computer is just going to correct the slop out of the base adjustment.

So in your opinion should we be running the max octane pump gas available. I fill up at the 1/2 tank mark. I alternate between 91 and 87 . On hwy trips is use 91.

 

[Noobz347]

So in your opinion should we be running the max octane pump gas available. I fill up at the 1/2 tank mark. I alternate between 91 and 87 . On hwy trips is use 91.

What is listed in the owner's manual for your specific vehicle?

 

[Bullitt347]

Top Tier fuels will have an additive package in the higher grade fuel that can prevent carbon build up on the intake valves.
The science behind it is pretty amazing. Lake Speed Jr. (The Motor Oil Geek) has done some You Tube videos interviewing people who work for the companies that formulate the additive packages for fuels. Might be worth a look.


View: https://www.youtube.com/watch?v=AWVMMmLqvuI