I've seen some assumptions on EvoM that load varies gear to gear. From a ton of datalogging I've known that this is not always a correct assumption.

Today I had some extra time on my hands and was working on my personal Evos tuning, so I decided to go through the gears and get some logs to show.

My one disclaimer is that I do most of my tuning and work with RPM based ecu-controlled boost Evos. MBC controlled Evos might be different.

Log of 1st through 3rd gear:



Another log of 2nd through 4th gear:



As you can see, the load only varies a very small amount, but not enough to land the tune into different load cells per gear and rpm. In this example, it stays in the same fuel and timing cells gear to gear.

Boost was logged with a JDM map sensor and the log reflects this. The JDM map sensor has no smoothing in logging so you might see some "blips" in the boost in the log.

 

My load number are usually different from gear to gear but that is soley because of crappy boost control..I spike higher in 1st and 2nd then I do in 3rd and 4th..Did it with my EBC, now it does it with a MBC..Probably a combination of a restriction in the 02 asking too much for a stock evo 8 turbo..I get boost spikes
I even ported out the 02 passage on my 02 housing when I first got it.
IT's really time for a new turbo and 02 housing!

 

I've seen the same thing Bryan. ECU Load is quite consistent at WOT in all gears. Spikes might be greater in lower gears and boost will come in quicker in higher gears, but those are really the only significant differences.

I often hear the different load in different gears comment about actual engine load as well though, which I still think holds true and is what causes the spikes and spool differences between gears. In higher gears the engine is under more stress due to gearing.

I honestly think that the term "load" is just incorrectly cited by some people who don't yet know the difference ... here in the ECUFlash forum we nearly always use the term "load" in reference to ECU load and outside of the tuning forums it's more likely to hear talk of engine load.

 

I'm confused, first you agree then you disagree with the paragraph above.

I am showing it above with data. RPM to RPM to gear to gear the load is almost spot on.

Yes if you start a pull in 3rd gear at 3k and at 3600 you hit 300 load, then you keep rowing through the gears you will never see 300 again as the the shift to 4th puts you into a much higher RPM spot.

Either way the tune only cares about Load the Ecu sees to set AFR, Timing, etc

 

What if I said my car still uses a unported stock 02 housing?

It's probably because of the MBC and non RPM based EBC.

 

I'm simply saying that there is a difference between ECU load (calculated value used by the ECU) and actual engine load (physical stress the engine is under). They are both referred to as "load" and it can be confusing.

 

Yea I understand, but what gauge measures physical engine stress?

The assumptions I have seen is that people say each gear sees different "load" so the boost, AFR and timing will be different gear to gear, which is not always true.

Btw, this reply isn't throwing grenades at you.

 

MBC will vary some since the boost depends on the intial spike. Even then, I am still with you on this Bryan that its not much more than a few percent load% variance. I will dig up some logs of my car to doublecheck exact figures but the most I have ever seen is 10% and its directly related to an increase in boost. When boost is constant, airflow is constant, and therefore load is the same.

 

Yea I have noticed MBC's like to spike on each shift gear to gear where ECU-based boost with a good solenoid (3port) tend to not do this. (if setup correctly)

btw, no error correction kicked in in the above logs. It was straight un-molested tuned WGDC.

 

double thread?!


i posted this in the other thread

wow awesome info.

is this using direct boost control via jdm map sensor? Hopefully not.

also more importantly - is this with lean spool disabled?

stock bcs FTW!!

 

dexmix I replied in the other thread.

Sorry I usually don't double post but I figured it applied in both sections.

 

Yeah ... people speak freely about things they don't always completely understand. I think that your data proves that ECU Load is essentially constant across gears. It makes sense ... only the gearing changes, not the engine.

I know your post isn't about physical engine load, but I think it's pretty well accepted that physical engine load does change between gears. Most of the time I hear the term it's in reference to this. I've also heard people say that boost changes with increased "load" in higher gears. I think it's true to some extent with a MBC setup (as you mentioned). That's pretty easy to test though ...

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So, you're throwing beers now? I just enjoy discussion man ...

 

Physical engine load is the same as our load that we talk about, as it is measured by airflow.
I bet this log looks this way for 2 reasons: 1. It's MAP controlled boost, RPM dependent, so it only makes sense that it should show the same load throughout gears - that's its purpose. If you had an MBC, results would be different i would imagine.
2. This is probably a dyno log. If you did a log out on the street, load should change because of air resistance. Higher speed should require more work, which means higher load. But again your boost control would probably even it out anyway.

 

It is MAP controlled boost, however no error correction kicked in during the logs so it's running purely off straight WGDC

They are both street logs.

 

I did a lot of cutting and pasting to make this fit, so don't get hung up by the deleted cells. Here is a sample of a log I did just 4 days ago. Even in the mid 300s of load, I'm seeing very little variance in load between 2nd, 3rd, and 4th gears. More than Razorlad, but still pretty close.