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3.6 - For Those Running Premium Fuel

Livernois Motorsports

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So the results of your 30ish horsepower gain was using E72 octane fuel, if I’m understanding you correctly? What were your results with 91/93 premium gas?
it's all in the video, did you watch it? There's a ton of good info in there, which is why we made it.

it gained over 50hp on E85, in the area where it matters. check it out, it's worth the watch.
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Tread4Lo

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@Livernois_Motorsports

What are your thoughts on coil packs to a higher voltage and more complete fuel burn? I know some people think they are hogwash and others that say it definitely provides some low end torque. That's where I would like these numbers to show up, low end under 3k RPM's.
 

Livernois Motorsports

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@Livernois_Motorsports

What are your thoughts on coil packs to a higher voltage and more complete fuel burn? I know some people think they are hogwash and others that say it definitely provides some low end torque. That's where I would like these numbers to show up, low end under 3k RPM's.
In our experience on basically every platform with COP ignition, the aftermarket has never proven themselves able to have a product that improves over stock in every way. Most of the times we encounter misfire problems with them, but the higher end ones that don't have this issue always worked better in one area, but not others.

The stock coils can easily fire a supercharged 3.6 on E85, so there isn't a deficit anywhere in their performance in our mind.
 

timn1984

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Investigate and research the 3.6 a little more and it may surprise you that the higher compression engine thrives on higher octane fuel. Believe Livernoise just posted something about their tuner recently and also provided background info on how much better the 3.6 delivers all around with premium fuel. I can’t find the thread right now but I’ll post it if I can.
I agree. I'm not the expert, but wince I have been using Premium gas I have been getting about 20-22 mpg on the road and 18-20 in the city. Before I was getting about 20 and 16. Not sure what it was due to but it makes me happy to spend the extra money for the better gas.
 

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five9dak

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Well geeze, glad we provided some good content for discussion and debate.

I will keep it as short as I can.

Item 1.

While this engine is "rated" to use 87 octane fuel, it is a compromise to do so. You've got something that is 11.3:1, and is designed to rev to nearly 7500 RPM (even if the factory limiter is lower), means you end up having to pull power back to be able to run 87 octane fuel.

Item 2.

These stay at 1.0 Lambda in the stock calibration for most of the run, go into enrichment, and then almost immediately into cat overtemp protection. 1.0 lambda has about the worst knock prevention you can get under a load, which means they have to pull even more power out of it. But this combination of low timing, and stoichiometric fuel mixture generates a TON of heat in the catalyst, so to offset this they then put far too much fuel into it to cool things back down. this equals power being low now from protecting the cat, because it got hot, quick.

so you have 2 items that create an environment that is very unfriendly to low octane fuel, and also limits power because of this. So the oem is calibrating around this "87 octane approved" mandate they were given, but a little secret is that all EPA fuel economy testing is done with 91 octane 0 ethanol fuel. Which is why so few vehicles actually are able to return the advertised fuel economy figures. So you have the CAFE side of the team developing an engine and calibration to be super efficient (relatively) under one condition, and then another team that's sole job is to make sure it can live with low octane fuel, with almost no control over the base engine design.

So we are able to get huge gains by allowing the proper balance for a richer lambda, combined with other changes to make it happier on low octane fuel, but you still have the fundamental limit of the engine design holding back the power due to 87 not controlling knock very well.

Now move to better fuel, which means you can actually start adding in power, rather than just removing the items limiting power.

Then add in ethanol being a 100+ octane fuel that has a dramatic impact on cooling off air charge and combustion chamber/piston crown temps, and you have even more gains.

Now, I am completely floored that someone on the internet would ever claim to not believe something posted by a company, just in utter disbelief. </sarcasm>

With that said, we would never stack the deck on baseline vs results. here is some insight into our method:

6 baseline runs done with 3 minute cooldowns, then we take the median result. in the case of the MOAB from the original video, there were runs as low as 213, and as high as 229. we went a little higher than median and chose the 224 run as we had 3 that were 223, 224, and 225. we did have 2 that were 213 and 215, and one that was 229.

Same goes for the final numbers. 6 final validation runs, and choose the run we feel is the median. the highest was 258, lowest was 244, but we had a grouping of 252, 253, 253, and 255

and yes, all done on the same dyno, the same day, by the same operator. No rookie stuff here. It's almost like we've been doing testing and validation for over 70 years or something...

Bumping this one because it is very relevant to the thread closed yesterday.
 

entropy

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I tried the highest octane fuel I could get here and saw no difference in MPG. In terms of power, I didn't feel any difference either, so if there was any, it was negligible. I'll continue to use what my manual tells me to use.
 

TheRaven

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I tried the highest octane fuel I could get here and saw no difference in MPG. In terms of power, I didn't feel any difference either, so if there was any, it was negligible. I'll continue to use what my manual tells me to use.
I've done this with every vehicle i've ever owned, still do - run three tanks premium, three tanks regular. I've NEVER seen tangible gains in power or fuel mileage by running higher octane gas with no other changes, and the JL is no exception.
 

Livernois Motorsports

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I've done this with every vehicle i've ever owned, still do - run three tanks premium, three tanks regular. I've NEVER seen tangible gains in power or fuel mileage by running higher octane gas with no other changes, and the JL is no exception.
Then it never left long term knock status.

The JL, as with most chryslers, will learn repeated knock situations and apply "long term knock control" where it pulls out timing no matter what. The MOAB we have was pulling out 6* of spark almost everywhere with 93 in it after the last tank was 87. with 87 it was 6* plus another 1-2. The point was that unless the ECM says that it's safe to start adding more timing back in, it won't. no matter how many tanks of 93 you run. You would need to meet the load/speed requirements to get it to start learning timing back in.

OR, disconnect the ECM, and it will revert on it's own. but the JL heavily knocks on 87 octane, and should be on 91+ for all engines. that's why they audibly spark knock with 87.
 

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TheRaven

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disconnect the ECM
I did this for every single vehicle...it was part of the process. Run three tanks premium (FIRST, so it should have never pulled timing to begin with), reset ECM, run three tanks regular.

but the JL heavily knocks on 87 octane, and should be on 91+ for all engines. that's why they audibly spark knock with 87.
This is absolute nonsense. It's really disheartening to hear a vendor that so many respect say something like this. It's not impossible that you have seen some vehicles that do this, but it's absolutely NOT true that they all do it. More importantly, pulling timing to quell spark knock is not a "problem" to be fixed - it's a normal function of an ECM, and it happens on all grades of fuel regardless...just introduce a sudden charge of humidity into the intake air and watch it pull like crazy, for example. Telling everyone they need to run higher octane to stop an ECM from doing what it's designed to do really makes me question why i'd want to trust you with my ECM.
 

AnnDee4444

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Then it never left long term knock status.

The JL, as with most chryslers, will learn repeated knock situations and apply "long term knock control" where it pulls out timing no matter what. The MOAB we have was pulling out 6* of spark almost everywhere with 93 in it after the last tank was 87. with 87 it was 6* plus another 1-2. The point was that unless the ECM says that it's safe to start adding more timing back in, it won't. no matter how many tanks of 93 you run. You would need to meet the load/speed requirements to get it to start learning timing back in.

OR, disconnect the ECM, and it will revert on it's own. but the JL heavily knocks on 87 octane, and should be on 91+ for all engines. that's why they audibly spark knock with 87.
Have any datalogs that show this? Or a dyno with ignition advance plotted?

Also, any idea if the 2.0's ECU works the same way?
 

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i used to run the mid grade premium in summer, whatever crap they put in the gas in CA in summer made the JL ping on hills or under load. /shrug
 

Livernois Motorsports

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I did this for every single vehicle...it was part of the process. Run three tanks premium (FIRST, so it should have never pulled timing to begin with), reset ECM, run three tanks regular.



This is absolute nonsense. It's really disheartening to hear a vendor that so many respect say something like this. It's not impossible that you have seen some vehicles that do this, but it's absolutely NOT true that they all do it. More importantly, pulling timing to quell spark knock is not a "problem" to be fixed - it's a normal function of an ECM, and it happens on all grades of fuel regardless...just introduce a sudden charge of humidity into the intake air and watch it pull like crazy, for example. Telling everyone they need to run higher octane to stop an ECM from doing what it's designed to do really makes me question why i'd want to trust you with my ECM.
Just go ahead and datalog it, you will see. when I say all, I do mean all of them do it, maybe not audible, but it is pulling out timing. The number of gladiators, and wranglers we have had across our dyno is not insignificant, and they all do it. 2018, 2019, 2020, 2021. My rental units have done it on vacation.

Remember, 100% of EPA registered fuel economy figures for all, yes, all gasoline vehicles is done with 91 octane 0% ethanol specially formulated cert fuel, same with emissions testing.

Retarding timing increases exhaust gas temps, which increases the chances of entering cat overtemp, which increases fuel use to cool the catalyst, which reduces fuel economy. This of course is separate from it making less power than on 91+, which does also make the vehicle work harder as well.

Have any datalogs that show this? Or a dyno with ignition advance plotted?

Also, any idea if the 2.0's ECU works the same way?
yes, they will be attached since the internet demands it (even though they could look for themselves on their own vehicles)

yes, all OEM's have this type of system. Gm has high and low octane tables, chrysler has "long term knock", Ford has octane scaling which blends to a octane adjust table and their knock sensor logic actually allows it to add timing if it can handle above and beyond the learn octane value, other OEMs have their own approach.
 

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AnnDee4444

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yes, they will be attached since the internet demands it (even though they could look for themselves on their own vehicles)

yes, all OEM's have this type of system. Gm has high and low octane tables, chrysler has "long term knock", Ford has octane scaling which blends to a octane adjust table and their knock sensor logic actually allows it to add timing if it can handle above and beyond the learn octane value, other OEMs have their own approach.
Thanks for this. I don't even have a 3.6, just an interest in tuning... and no way that I know of to datalog my JL. I appreciate the time you've taken to explain everything.
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