Black LS1 T/A

I've time-marked his discussion so you go straight to the recommendation he is making.

"How to setup a base fuel map for larger displacement LS engines"

He's saying copy the table of VE values and update to your new displacement.
(Increasing Displacement in the software scales up the VE vales, as you probably know.)
Then, he pastes the old VE values back into the VE table.

I'm not understanding. If you increase the displacement value, and the VE values adjust as a result, that is not what is intended by software design?


What is the logic behind changing the VE values back to the old displacement VE values? Help me understand the logic. Is he right or wrong?

NicD

iTrader: (7)

When you increase the cylinder displacement setting in HP Tuners the VE table automatically scales downward because the VE is just a converted value by the software from a raw number multiplied by the cylinder displacement. That means you need to more than likely scale your VE table back up by whatever percent your engine increase is to get it back in the ballpark as a start.

Full Power

Volumetric Efficiency is a function of intake manifold plus cylinder head flow and camshaft specification. The swept cylinder volume alters neither.

NicD

iTrader: (7)

say wut?!?

Black LS1 T/A

If you watch his video, you see the VE table change when he adjusts Displacement. Then, he copies the original values back in.
Has HP Tuners changed the way it operates since then?

smokeshow

iTrader: (17)

That's called a ghost toon. Sneak some of that fuel out til it gets lean enough to chop like a big cam and you're golden.

Really though, that sounds very sketchy...never heard of that bug/feature.

ChopperDoc

No. Absolutely ******* not. Why? PV=nRT. That’s why.

Pressure x Volume = moles x constant x temperature

So… what he did was, he increased volume, then decreased the “moles” essentially. He told the PCM that the volume was bigger, but then changed the only variable that we can alter (other than volume that is) saying it was less.

Now, what is the ONLY result this can be? Lean. Like really ******* lean.

Yeah I’m a little drunk but this is a dumbass video. If you would like I can literally demonstrate this exact math and show why this is about the dumbest **** I’ve seen someone post on YouTube.

Also, it’s been a few years since I’ve updated my software, but, I don’t recall the volume change having anything to do with VE. As in you still have to change it manually after the fact. Every scale I’ve ever done you still have to apply the change directly to VE and everything else in the tune. Maybe that part is new. If so, he’s even more wrong because he’s making it even leaner.

Don’t try this at home kids. This video is complete horseshit.

ChopperDoc

Here’s a video explaining why this dude is full of ****. Math is math. You can’t cheat it. Changing the volume and leaving everything else the same will net lower moles in the calculation, meaning the PCM will spray less fuel.

I have NO IDEA why anyone would want to run this, or why you would lower the VE at all for any reason rolling into a fresh build tune. Most guys I know, including me, INCREASE the VE by at least 15% as a starting point just to stay on the rich side. And I say at least. If that **** just got a true 3/4 cam with a 427 bore it’s probably gonna be a 30% increase over stock just to begin. No issues running rich. Big issues running lean.

What he is doing is setting folks up for detonation and/or pre ignitions. If this is a tutorial it should be reported. Straight dangerous. Just saying.

Here’s why he’s wrong:

https://m.youtube.com/watch?v=QVGC9Jydujo

Black LS1 T/A

Thanks, guys... what you are saying makes total sense. What he was saying just sounded crazy to me.

Black LS1 T/A

Thanks for that link! I'm watching now! I'll thumbs-up and leave a comment

NicD

iTrader: (7)

Holy crap some of you guys are completely missing this and don't understand what is actually happening here, let me give a history lesson on the VE table and cylinder volume tables with HP Tuners for Gen3 applications...

Back in the old days of LS1 Edit the VE table was just displayed using the raw values from the table in the bin file in the format of g.K/kPa which were just numbers in the thousands. Well a lot of people didn't know what that was so HP Tuners chose to format the DISPLAYED VE table data a bit differently to show a percentage that more people were familiar with so they normalized the raw data values against the Cylinder Volume table (VE% = VE value / (178.33 * CylVol)). This is why when you change the Cylinder Volume (Gen3 applications only, they changed this going forwards with the Gen4+) the VE table "changes" on it's own even though the fueling doesn't actually change because the raw values don't actually change in the background in the actual table. For example, if you raise the cylinder volume table by 15% the VE table will drop by ~ that percentage, but that doesn't change any fueling just yet because the raw values in the VE table are identical, they are just DISPLAYED differently in the editor since they are normalized against the cylinder volume table. Do that same test with a Gen4+ file and it will have no effect on the VE table itself, because HP Tuners is not normalizing it against that variable/table anymore because it caused even more confusion like this.

In that first video the guy is just explaining that when going up in displacement one of the quick and easy ways to "add" fueling to compensate for the displacement increase is to just copy the table BEFORE modifying the cylinder volume table and then pasting it back afterwards. All this does is just scale up the existing fueling from before by the approximate percentage change of cylinder displacement, you will still have to actually tune it afterwards. He is not wrong at all and is 100% correct in his method to easily add fuel to the table for a given size increase as a STARTING POINT.

Now to those of you who say that the VE of an engine won't actually change if all you do is change the physical displacement of it you are also very mistaken. This is a different discussion then above, but if you take the same heads/cam/intake/whatever and move it from a 4.8L to a 7.0L I guarantee the VE of that engine is going to change at every RPM/load point.

ChopperDoc

I didn’t look to see which direction the numbers were going in his demonstration. I can agree with moving it back up, as a start point. Pretty sure I mentioned I’ve never noticed that occur when scaling. Perhaps it’s a function that occurs when increasing the displacement rather than decreasing, because on my version it doesn’t change the VE when I reduce the displacement by the scale percentage.

Personally I’d still increase it further to account for major mods, but yeah my assumption was he was reducing it it stock. Even if raising it it’s not going to be right, since the displacement increase must be added to the stock value to make PV=nRT true. Increasing “V” must be accounted for by also increasing “n” to make the result work out the same. N comes from the VE setting.

Makes me want to go play with it because real world numbers can and do vary for various reasons.

NicD

iTrader: (7)

I know some of you guys are newer to this stuff but it's worked like this since 2004 (03 maybe, not sure it's been a LONG time) in EVERY version of HP Tuners on Gen3 applications and it goes both up and down as it's directly scaled against the cylinder volume table. Please stop quoting the Ideal gas law, yes it's built into the raw data table calculations but it has absolutely nothing to do with this discussion.

smokeshow

iTrader: (17)

I haven't done enough engine swaps on gen3 I guess. Don't know why I didn't notice this before. The VE table and the displacement values are the same exact data in the hex, but only the VE table is changing the cals since the displacement is calculated.

The old 'gen3' code had all been purged at GM when I worked there, so I never got to see this for myself...otherwise I'd have spotted that. Got me lol

Fast355

Actually ideal gas law does have something to do with VEs. I set my tunes up MAF only first and then get really close to the actual VE table datalogging. I am using MAF/IAT/MAP/cylinder volume to derive VE numbers and filtering data to smooth transient spikes as well as cells that do not have more than ~25 hits.

BCNUL8R

iTrader: (2)

I can tell you are a professional tuner. I am not and I've learned a lot since the time I made that video. Yes that is me in the video. I can also tell the other non-professionals here speaking in theory, but not real world experience that this combo put together 3 years ago was very rich to begin with, but safe. It was a quick way to get a start up tune and starting point nothing more. Just common sense approach from a rookie that learned how to tune with carbs and reading plugs before everything was done with lap tops. I only have maybe 4-5 years of experience with hptuners and only had about a year of experience at the time I made that video. I don't remember the boost level I started at with that brand new engine that I built, but it's at 20 psi peak now and running well. Again to the people saying this would be dangerously lean based upon theory it was actually rich. If I remember correctly only slightly rich at idle and part throttle, but mid 10's AFR in boost when I was targeting about 11.5 AFR. This is also a speed density tune no maf. Engine does not use oil and is very happy 3 years later at 20 psi. I am far from an expert, but I had some friends that wanted me to put a video together of how I did a few things. The only videos I've made were for friends not living near me that wanted to see how I did some specific things. This is one of those.

My engine is a 377 ls3 block that I used this technique on for a start up tune, but in this video I used a 408 which is what my friend used for his start up tune that worked for him as well. Gave him a starting point that was very close and safe.

Black LS1 T/A

Thank you very much for having the transparency and constitution to take the initiative and respond to my post.
The whole discussion has been very helpful and illuminating.

One reason I asked about the video here, is, though I didn't understand the reason for retaining the VE values, your information in the video overall seemed helpful, and it didn't seem like you would just be putting out bogus information.

I'm still re-reading comments to make sense of it all.

Black LS1 T/A

Thanks for sticking with the conversation and giving us that historical insight!

NicD

iTrader: (7)

I have been tuning since around 2000 and have done so professionally since about 2003. You were not wrong in that video and were onto the right concept, it's just people not understanding what is actually happening behind the scenes and WHY it was a good starting point.

Black LS1 T/A

Here is how EFILive functions when you perform a Displacement Adjustment: