True. There is not as much to change after the MAF though. From there it is a pretty straight shot...but it would affect it.

 

Mr. Granatelli,

Thanks for taking time to spend some time with us on the site. As you have a lot of time invested in MAFs, I think folks should realize how lucky we are to have someone of your background on here.

Your family's record of accomplishments is certainly impressive, and certainly speaks volumes about your deep seated intrest in motorsports.

Anyhow, the question has been posed how does speed density compensate for changes in IAT, and changes in barometeric pressure, or other such changes.

There are a few folks here in the states who understand Speed Density. But honestly, most folks really don't. Most folks read the SD FAQ and thats as far as it goes. I was lucky enough to spend time with the folks who have been doing speed density for MANY years.

Believe it or not, those innovators are not in the United States, they are in Australia. As was stated, the Australians even had a factory Holden with SD from the factory. For various reasons, I can't give away all the other factors that some folks miss when doing SD. It suffices to say that folks are in SD, but there are some key things to tuning in general that basically everyone is missing.

Anyhow, the car does alter fueling based on IAT. So, I set my tune, and got it looking beautiful. ThenI disconnected the IAT. The car assumes that the temp has now dropped to -40C. And the car immediately begins adding fuel. The 02s read this the fuel trims going highly negative (as the car is now much richer, and to keep stoich the car has to trim fuel). This was certainly one of my concerns about SD was how it was going to compensate. But it does. The IAT keeps track of air temp. The MAP keeps track of pressure, and it all works quite well.

Anyhow, there are folks much more qualified than me to explain exactly what the PCM is doing, and why. If you want to discuss SD tuning with the folks who do it every day, and do it VERY succesfully I suggest you speak with Sam @ Sam's Performance in Sydney. You can also PM PlanB (a moderator on this site) who is a close friend of Sam's and is darn good with the SD stuff himself. Martin (Street Tuna) who runs a shop in Sydney also, are all on top of their game and are all VERY well versed in making SD work (well, if you consider an almost 800 RWHP (on a U.S. dyno) stock cubic inch daily driver with an SD tune good ) . They can also be found on ls1.com.au.

One of the big advantages at least that I have seen was with the Aussies making 8 runner throttel body setups (much like an old Hilborn setup). I saw some really large cam'd cars run a drive much better with an SD tune and an 8 pot setup than any MAF car I've ever seen bar anyone doing the tuning...

I mean an airmeter is nice and all, but it is a restriction none the less at some point. The other issue is that unless you have a way to run multiple air meters, you are stuck with a single inlet point.

The issue that I saw lots of was with all the overlap of a big cam, the MAF becomes unusable at low speed with the airpseed issues of a big cam with lots of overlap at idle.

I've said this before, but I persoanlly drove Craig's Ute. Craig owns Craig Automatics. He is "the" guy down in Australia for Automatics. Anyhow, his daily driver street car was a 273/273 104LSA 103ICL with an 8 runner setup behind an automatic with a decent stall. Put a cam that size in any 346 here with a MAF and you'd be lucky to get it to run at all.

Here is a video I shot @ Sam's of a daily, and I mean daily, driver 242/242 106LSA 105 ICL Holden. The car is a ***** cat.

The things you find out about car after a MAFless tune running in SD is this.

The car idles better.
Throttle response is crisper
Overall drivabilty is 1000X better on a big cam car. In my case with help from my friends down under I was able to SD tune a Corvette with a BIG 24x/24x cam and I can lug it down to 850 rpms with no bucking and surging in 3rd-6th gear... With a 4.10 and the deep 1st and 2nd the car has too much gear to give it any load so the cam surge just a bit still in 1st and 2nd (I'm still working on that though). This is 1000X better than any MAF tune the car has ever had done by anyone...

Here is a video of an Aussie SD tune...

http://users3.ev1.net/~black_ops/video/242-106.mpg

I'll send a PM to Pete to see if he can drop in for some of the discussion. But please, keep this going. I think Mr. Granatelli could all teach us quite a bit about the hows and why of a MAF. If anyone can, he certainly qualifies, and I welcome any input he might have to this topic.

 

link doesnt work...i wanna see that vid damnit

 

fixed.

 

well damn...ive heard 224 cams idle rougher

 

Yeah Nick, talked to a friend about all this jazz. He's a controls engineer. Showed him the bridge and I also have a SAE paper explaining how the GM MAFs work. err at least I think so, I just skimmed over it. We tossed around ideas and a lot of what you stated was correct. So real quick

The TF is part of the circuitry and "hardwired" into the MAF itself. According to him

"The transfer function is part of the circuit dynamics"

So the MAF tables are the ratio of the input to output. In the MAF's case its the ratio of massflow -to- frequency output and you get the accompanying curve.

Next thing we touched on was how a change in a lid could change the transfer function. We assumed that conservation of mass applied, i.e. mass flow = mass flow out. Since the sensor is a heating element the lid would change the velocity profile across the MAF, not necessaryily the mass flow under certain conditions. Something you or someone else mentioned. That affects the heat transfer rate and could skew the TF but not necessarily the mass flow rate.

My mistake was looking at the MAF tables as strictly an output and not a ratio of input-to-output.

So, thanks for your patience , next beer is on me!

 

Oh, It's a MAF debate..... Yawn....

 

everyone is MAF debating... or is it debating MAFs? I always get them confused...

 

No everyone is MAF deleting. This is a MAF discussion.


BTW, someone asked what the 8 pot setup look like. Here's a pic of two... They are big pics, so I posted a link instead of a direct link into here.
On the dyno
http://users3.ev1.net/~black_ops/AUS/DSC00027.jpg
In a car
http://users3.ev1.net/~black_ops/AUS/DSC00037.jpg
Spare trumpets
http://users3.ev1.net/~black_ops/AUS/DSC00026.jpg

 

Enough with the top secret stuff, how are we ever going to learn......SPILL IT
TTT gots to keep this one going.

 

What I'm talking about is some of the basics folks miss in either SD or MAF tuning. This won't affect your ability to get the car in SD.

Its just what just what I have seen no one mention in any posts ever. You don't see it in the tunes, etc...

I'm not trying to be mysterious, but this is the sort of info that separates one tuner from another. In the case of the folks that have shown me what to do, if I go post their hard work on the internet, the shop across town with the guys who wish they knew this stuff would all of the sudden benefit from this knowledge, and why would you go to the guy "who knows" when some "copycat" could benefit from that knowledge with no time or money invested in getting there.

Its real world, and real money. Folks have already shared how to go SD, and up until recently precious few folks knew how to do that either. Shops got paid good money to do an SD tune. They had time and money getting that worked out and developed also.

I will say that HP tuners has all sorts of functionality that folks just ignore. They hit the stuff in the FAQ, or the tuning for dummies threads, and they leave it at that. Spend a little time in the tables, and concurently read the help file. The Gm computer is very powerful, and when you understand all it can control its a very powerful tool.

It amazing what you might learn when you spend some time at it....

 

well there you go every one stop reading this fourm and just do it your self and learn it all for yourself.

If that was the attitude of the people on here there would not be a hp tuners software or even ls1edit. this stuff has ALL come about because of people sharing what they know. yea there is a small advantage to keeping it to your self but it does not help out in the long run. if you are going to come on here and say ha ha I know something that you don't, then just stay away.


More Than Zero

 

<--- Shares a lot.

 

Lets get one thing clear, and I mean crystal clear. I'm not against the sharing of information. If you look at the posts I make in the internal section you'll see that I share a bunch of information based on what we have learned racing.

I'm not a professional racer. So, I have no issues sharing what I have learned.

On the other hand I have been helped by shops, and shop owners who livelyhood depends on some of the advantages their tuning brings. Those advantages re based on their own hard work. In sharing those things it was specifically stated "this is not for public distribution". If it was, it'd already be shared with you. I'm not saying this is going to make you 50 more HP. The simply fact of the matter of what I am saying is that folks treat tuning just like they do H/C installs and other things related to the cars.

Most folks read the H/C install FAQ, and they go put a cam in. They never do things like check PtoV. They never degree the cam. They never check quench. They never do all the things that many of the shops do to maximize those combos. Then they wonder why their results are less.

In the case of tuning SD, or with a MAF its the same deal. Precious few folks have ever even opened the help file to see what certain values even do. You have these tabs staring you square in the face in HPT, and you never use them to your advantage.

I'm not making a post going "nah nah nah, I know something you don't". I'm trying to encourage folks to think a bit more about tuning, and to educate themselves on the PCM, and what it can do for them. SD is just one of those things.... The PCM is all about air fuel and spark. Folks spend very little time optimizing any of those past getting the car to idle and run @ WOT. All I am saying is most folks leave stuff on the table...

As for sharing vs keeping it to yourself. Keep in mind that HPT's original intent was to make an open source freeware tuner package. I don't begrudge those guys for making money for thier fine product and the efforts they have made. But don't think they are giving this product away. Ken Kelly has made plenty of money off ls1edit (over a million if you do the math). Same thing there. Are they giving that away or keeping it for themselves?

As far as learning it for yourself, thats part of what I am suggesting. Spend some time learning more about the software, and share what you know. All I am suggesting is folks spend a little more time educating themselves and it makes it better for everyone.

 

I agree to an extent...some of us have gone through the help files and maybe we dont understand what some of the different things do or just dont understand the lingo used in explaining it so we come to hptuners forum or here to try and find out for people possibly more knowledgeable then us. There are people a hell of a lot smarter then I am in the tuning game that still havent scratched the surface and ask questions here and there because its always going to be a learning game. The phases tuners have gone through is proof of this because everyone is looking for the holy grail of tuning and to find what works best in all applications. I dont know if there is such a thing and I dont know if anyone does...remember gm went from maf to speed density back to maf in the late 80's early 90's so obviously they couldnt figure out what was best. I know you have shared tons of information not only about tuning but motors and their inner workings and this is appriciated what I think everyone is having issue with is that you "stirred the pot" with what you had said and have some people up in arms and just made a few smart people think a little harder about what they've been doing in hopes of figuring out what you meant...hopefully there will be more of the latter and they will figure it out in due time.

lata
Bill

 

my point is that the people reading all 6 pages of this post and contributing to it are not the ones who don't even learn what the tabs are/do. and that posting on here that there is a solution to the problem but I'm not going to tell you what it is, Is not helpfull in any way.

So if that is the best that you can do save it for someone else. If the information is propriatary then don't bring it up in the first place to justify your argument and then clam up hiding behind the "Propriatary Information".

This is bad form and leads me to discredit the information and the person supplying the information. and if you are protecting the propriatary information that these shops depend on for thier livelyhood then you were compromising you agrement to not disclose the information by sugesting that we learn to do it on our own.

In short and I will stop ranting now, This form is about sharing info and raising the state of knowledge of the LSx platform and I dont think that this specific post of yours that I have a beef with does that.

More Than Zero

PS this is not intended as a personal assult I'm just taking exception to this post and not the person or any of your other posts.

 

yes I'm more vette specific and I'm not on here telling you that I know how to do something but I'm not going to share the info with you.

More Than Zero

 

Obviously you still haven't read what I posted, or you simply aren't comprehending it. So, I'll spell it out very slowly for you and perhaps you'll catch on the 3rd go around.

What I am referring to is the fact that there are lots of sections to the PCM. There are lots tabs in the HPT software. Lots of folks begin and END their learning about the PCM with a couple of general threads that have been posted on a couple of sites.

A few folks have delved a bit deeper and understand the interaction of these sections. Here's a novel concept. Did you realize that certain tabs on different pages in HPT interact with one another and that changes in one section may affect or negate actions in other parts of the PCM.

The stuff I am talking about makes your tunes more consistent, etc...

I'm not trying to justify any position by citing proprietary information. This post was about the 3 bar setup in HPT. The discussion then went to MAF vs MAFless. I simply pointed to some of the best MAFless tuners out there, and some discussions on that came up.

If you choose to discredit anything I say based on the fact that these folks don't give away their tunes, great.... Knock yourself out. It doesn't change facts.

I agree that this forum is all about the sharing of information. I'm all for that. I'm not violating any agreement I have with anyone by telling folks to get educated. This is the same thing I brought up in the cam thread. If you want to do things the right way, you need to get educated. I'm simply trying to get folks to educate themselves by doing something as simple as reading the help file in HPT to make them better tuners. If that offends you, sorry, can't do nothing for you....

 

its all cool but let me ask a few questions

1. if all of the info that you are refering to is spelled out in the HPT help file then how can it be propriatary information?

2. do you know that trying to get people to educate themselves works better if you just say hey there is a great section in the HPT help file that covers this I think it is in section XX.

3. did you not understand that I already understood the "sorry, can't do nothing for you" and can state that you didn't do anything for me in that post.

anyway this is getting into a pissing match and I'm here to learn this stuff and not derail the thread which i have done so I apolagize for that and also if you took any of this as personal.

peace

More Than Zero

 

ok let's drop this from this thread... Original intent was to discuss the 3 bar MAP, feel free to start another thread on the topic of SD tuning where we can all discuss other tables/methods ... to try to think "outside the box" and learn about these other tables as a group instead of bickering about them