Video shows that octane doesn't make power.

From the manual:

 

You guys need to get rid of your butt dynos they are not accurate.

 

That crate small block engine is not knock limited in an un-boosted configuration. Most production engines are. I'll go as far as to say that ALL current production engines are knock limited and the EFI system is constantly pushing against the knock threshold and backing off when it senses detonation. The detonation resistance of the fuel and therefore the amount of timing that can be added without achieving max cylinder pressure @ MBT crank angle will always result in more torque made by the engine assuming the ECU has the authority and overhead to take advantage of the ignition timing potential.

This video is misleading when considered in the context that it and you present it.

 

Costco may be top tier, but Sam's and Wal-Mart are hit and miss depending on which oil company has the current contract,from the research I did. I stick with Quiktrip as it publishes their top tier status and around here, stations are plentiful. Plus their snacks are pretty good. I won't make a special trip to Buc ee's but their gas good to go with E0 available.

 

I don't think so at all. The point is that the fuel does not contain more power. Higher octane is only beneficial if the engine is designed to use a slower burn (higher octane) fuel.

 

Every modern EFI system can advance and retard ignition timing across the load/RPM range to varying degrees of authority, resolution, etc. VVTI is not effectively anything except changing the camshaft timing relative to the 0* setpoint. You could think of this as variable compression ratio because it will control cylinder filling and scavenging efficiency, but it's not really the same as lowering or increasing CR from a cylinder pressure point of view. It influences ignition timing, but that is a cause and effect thing.

 

https://gfycat.com/evergreenjointfish

 

The chemical energy in gasoline is a constant. The more additive used to increase octane rating, or the more ethanol used, the lower the energy density because some gasoline is being replaced with additives/ethanol. So higher octane rated gasoline usually contains less energy per unit mass or volume, depending on what is used to increase the octane rating. However, no ICE engine is able to extract all of the chemical energy of the fuel through combustion, about half of it is wasted as heat right out the tailpipe. So, if an engine can extract more energy from the fuel from more efficient combustion, then it will make more power. Increasing the ignition timing advance will result in more efficient combustion on virtually every modern production vehicle engine and a fuel's resistance to ignition is the most powerful way to allow for a more advanced ignition timing angle. octane rating is the measurement of a fuels resistance to ignition. So, saying that octane rating of a fuel does not make more power is technically correct and if the engine ignition timing is not changed, or is already at the most efficient ignition timing angle, which it is on that specific crate engine, then sure, it will not make any more power. That is not the case for a modern production car engine and therefore is misleading in the context of a online forum about a truck with a modern EFI engine.

Higher octane fuels don't burn slower, they resist ignition better. The flame front propagation speed is not going to change from one octane rating gasoline to another enough to matter. The cylinder pressure at the time of combustion as well as the A/F ratio will have far greater effect on flame front speed than any additive or octane improving substance used in gasoline. All modern EFI engines have the capability to change the ignition timing, so they can take advantage of changes in the fuel's octane rating. To what extent they can take advantage is what really matters. The 2GR-FKS can advance up to the knock threshold on 93 octane fuel no problem.

 

This is a modern engine. It's a basic ls3 not some voodoo magic engine. It's a good example to show that on very popular performance platform that more octane doesn't necessarily mean more power.

 

Getting a ping decelerating, or going downhill, which never had that happen before in any of my vehicles…if they do ping it is under load. Thought it might be a loose heat shield rattling, but the truck only has 13K miles on it. Got under there it looked around nothing loose.

Don’t know, run top tier in it.

 

That was a crate engine with aftermarket heads, cams, etc made for HP. There was no discussion about how the EFI system manages timing and it sounds like the timing angle for MBT was already achieved on 87, so advancing ignition timing further was of no benefit. That is not the case on any production EFI engine I've ever heard of or tuned and certainly not the case on the 2GR-FKS.

 

I think I highlighted the actual important part.... and it goes for any engine... I still don't think it's misleading at all. If an engine can take advantage of the higher octane, it will make more power.... an example is the higher octane tunes available for the 3.5 available aftermarket. In the case of stock, I don't think there is much to gain at least I haven't someone dyno test it. Have you seen this? I'd like to know the difference.

 

It too is a modern EFI engine. GM has been allowing the ECM to adjust timing to under knock since the early 80s and even on carbureted engines..... what's on that crate engine will be very similar to what you can find on the new car lot now.

 

The 2GR-FKS, and any other production engine I know of, is not able to achieve MBT ignition timing even with 93 octane fuel on anything other than a cold day, so the part you highlighted is not true for most engines. There is some to gain with the stock tune on the 2GR-FKS. Whether it is enough to justify the cost of higher octane rated fuel is up to each individual that cares to investigate it. The engine in that video is a crate engine that doesn't have any restrictions like, fuel efficiency, emissions, reliability, cost of manufacture, etc to worry about. It was built for one thing, to make power. I have a lot of confidence saying that if they did the same test with a engine and EFI system from a production vehicle, they could probably just run it on 87, let the timing/KFB settle in, then switch to 93 and do the same runs and watch the timing/KFB numbers shift.

 

No.

That would be saying that GM is leaving fuel efficiency AND power on the table. GM and everyone else, is pushing the ignition timing up against the knock threshold. That crate engine's knock threshold was beyond the ignition timing for MBT, so further ignition advance was of no benefit.

I should clarify that my refence to MBT is "Mean Best Torque" angle and not "Max Brake Torque Timing" as many tuners refer to the latter as MBT (incorrectly IMO). Max Brake Torque Timing is just the ignition timing that the most torque is able to be achieved at. Mean Best Torque angle is the theoretical crank angle that at which ignition timing would result in max cylinder pressure at a crank angle of 90*, which in turn creates the most torque because of physics. That ignition angle varies depending on CC shape, volume, design, etc. many variables.

 

Yes, what is on that engine (we were talking the efi/management system) will be similar to what is on a the lot. The parameters for the tune for the specific parts in the engine (heads, cam, injector size etc) will be different....

As far as knock threshold, yeah. Again, have you seen that the 2gr-fks in factory form make more power with octane change only? I have not seen it.... only with aftermarket tuning.

 

This engine certainly has restrictions. You keep acting like it's some all out build. It's a very basic engine for people looking to get the benefits of a modern engine in an older car. It's 8500 and comes with 50k mile warranty. This is very close to what a similarly run stock ls3 would make power wise.

Here's a dyno of a similarly configured ls3. Ironically enough at the same shop with the same tuner... It made 500 hp.

https://www.motortrend.com/how-to/1504-chevrolet-performance-ls3-camshaft-dyno-test/

 

It can't be, they use total timing for their baseline ignition timing. That a static timing angle. EFI systems change total timing constantly, based on RPM, load, KFB, AFR, etc. They did not do any of that if they just used a total timing of 29*. They also say that adding timing advance does nothing for improving power, so they apparently already reached MBT timing angle at whatever the critical load/RPM they are tuning for.

 

E85 saving me money right now. Under $60 to fill the caddy. Still saving even with the mileage hit.

 

While I wasn't there with them, baseline doesn't mean static. Then engine will still adjust to feedback. What they are working with is a variation of a production engine designed for a drop in engine replacement solution to give a good user experience.