Speed density vs VE, '88 electronics, thoughts..

[c2xejk]

It always a fight to get the most out of a setup... You change the plenum and you have to re-evaluate the cam timing, spark timing, runner length, etc... That is why I have spent some time on the dyne testing and tweaking.

With the new setup, I have noticed vacuum stays a little high at WOT. So I have been playing with a different TB/plenum. I probably need to consider piping to the TB... Maybe more of a "ram air"... or atleast CAI...

If you are not fighting for every little bit, then you are either lucky or not bothering to tune...


So are you backing off your statement about the O2 and 85% injectors? There are some MAF systems that still default back to speed density under many conditions...


The reality is we need to figure out the stock computer. I have made several requests for some controllers. I am interested in trying to modify the VE tables for the '91 (and possibly others of that vintage.)

I have a friend that has offered to help me figure you the tables. Yes, he has considerable experience doing this. He recent project was setuping a '98+ vintage GM PCM to work on a supercharged big block engine...

Right now I just need a few extra controllers to play with... So help hook me up with some '91 3L V6 controllers and I may be to figure a lot of this out... Yes, I am willing to pay for them...

[Ondonti]

Quote:

Originally Posted by RoadWarrior222 Jeebus, I know the damn thing should be good for more, I'm not saying there's a hard limit, it's just that approaching that point it seems everything has less and less effect, stuff that you'd figure would be +20HP on any other motors gets like 3-5 or so. Ed you're even saying that, you're at about 183 crank and you're having to fight for every extra HP tooth and nail now right ? All I know about the mitsus is what I skim off places like 3si, where I'm not a member so don't seem to have a search function to pull it all up again. But SOHC 12V guys there are claiming like 20-25WHP dynoed gain from K&N intake and an exhaust. See figures like 167WHP just from that. The internals are the same. I've seen mention of folks there building 12V SOHCs that "hang with" VR4s on the track, in the high 13s, can't find build lists for them, figure they have to be over 200HP though. Okay so those guys start with a different plenum and bigger TB, but after we've done all we can to those on our motors, which only seems to get us 15HP to their 20 (141ish stock vs 161ish stock, haven't seen anyone claiming much above 150ish with just plenum and TB mods) we still don't seem to get 20WHP with an exhaust and "intake" best figures I've seen anywhere for those on ours seem to be about 15 again. Just saying that the overall impression I get is that we get only about 75% of what they do for same power adders. I see what you're saying Brent about setting the fuel up for 12:1 on the dyno at 5000, I presume you've seen figures from that? What are those? Of course I know that under a very limited range of conditions you can make the motors behave. I don't beleive there aren't VE problems with that though, it would seem to me that it would be pig rich at idle, and your adjustments would get tuned out pretty damn quick if you left it idling very long. Anyhoo, if you guys knew of anyone making over 200 crank verifiable and repeatable, on an untouched SMEC/SBEC you'd just point to that, and not have me wasting my time digging out every example in the world of people failing to make it.

I spend a LOT of time on 3si and there is nobody claiming those numers. not even close
No sohc 3000gt's are even in the 14's so how could you say 13's.
There is one person, Sunmind, and he has a 20,000 dollar sohc motor and he still doesnt have any dyno numbers. These are facts. I dont know where you are getting this false information.
I think you are getting things you read over there mixed up....and you cant compare dyno numbers unless is a back to back situation on the same dyno same day. Even though dyno's try to be accurate, there is just too much BS in the dyno business.

You have not tried any of these fueling things with the 3.0 and you are just guessing.

Why do you think the 3.0 would run pig rich @ idle when it sees 12.5 a/f ratio @5000 rpms?
Here is when you prove you dont know what you are talking about.
Ive done this before, you havent. Once the motor goes into open loop, it will compensate to reach 14.7:1 during idle and cruise operations (as long as the computer has the capacity to change that much). THe computer doest say "things are broken I give up"

my 3.0 was set up summer of 2005 to run 12.5@ 5000 rpms when the computer was cleared....and it doesnt "unlearn" this instantly. This is a slow process.
past 5000 rpms the a/f ratio leans out because of the stock VE curve, but my peak hp is still maximized.
No dyno numbers.
im trying to help you understand.

MAF or SD the only difference you will see in power when both are tuned for 12.5@5000 rpm is whichever motor is breathing in more air. The SD will always outperform a MAF engine in that regard, even if it is by almost undetectable amounts.

You seem to think there is HP difference between the 12v engines that is cause by MAF vs SD but that obviously is not even close to true.

[tkelly27]

Quote:

Originally Posted by c2xejk It always a fight to get the most out of a setup... You change the plenum and you have to re-evaluate the cam timing, spark timing, runner length, etc... That is why I have spent some time on the dyne testing and tweaking. With the new setup, I have noticed vacuum stays a little high at WOT. So I have been playing with a different TB/plenum. I probably need to consider piping to the TB... Maybe more of a "ram air"... or atleast CAI... If you are not fighting for every little bit, then you are either lucky or not bothering to tune... So are you backing off your statement about the O2 and 85% injectors? There are some MAF systems that still default back to speed density under many conditions... The reality is we need to figure out the stock computer. I have made several requests for some controllers. I am interested in trying to modify the VE tables for the '91 (and possibly others of that vintage.) I have a friend that has offered to help me figure you the tables. Yes, he has considerable experience doing this. He recent project was setuping a '98+ vintage GM PCM to work on a supercharged big block engine... Right now I just need a few extra controllers to play with... So help hook me up with some '91 3L V6 controllers and I may be to figure a lot of this out... Yes, I am willing to pay for them...

My local 'yard sells ECU's for $25 a piece, I'd be happy to get them to you for the price I pay + a really reduced rate of shipping. It might take a little while though, PM me with exactly what you're looking for and I'll keep my eyes open next time I go. Once the 3.0 ECU is mapped out and can be setup for boost, every $100 V6 craigslist piece of crap becomes a candidate for a big turbo and some junkyard engineering.

Also on the SD not being able to compensate. We've got lots and lots of proof on this board that the stock SD calibration for a TD is capeable of handling intercoolers (from stock to gigantic on cal's never designed for IC's), exhausts (from clogged cat's to 3" swingvalves with open down pipes), and some people have even gotten away with more. When you start getting into head work and the like, then you're running into problems with the stock cal under 14.5psi (or is it 14.7? I can never remember what a bar is...).

On the MAF side, if you hit a certain flow level, that's it, game over. On a DSM it occurs at about 14psi, which is a freaking fast car, but if you have head work, header, IC, cam's, it will happen sooner and you can't get any more power out of that computer and MAF setup. Even if it occurs at 8psi, you will not be allowed to go up to the 14psi which you could before. I can't imagine the V6 computer not having fuel cut, and I can't imagine it not occuring if you stuck a turbocharger on it. That is to say, MAF's have severe factory limits as well.

Both have strenghts and limitations. Nobody who is serious about tuning messes around with MAF systems if they can avoid it.

[Shadow24V]

interestingly enough, im curious to see what my 24v will do with the MS SD system as the factory MAF system was rated at 205 CHP (probably less in reality) but with a good tune, i HOPE i can break 200WHP.

it also helps that the SD setup on the MS unit is simple to implement hardware wise as my motor came sans a MAF and such peripheral items.

but to play devil's advocate - the infamous "Joe's GTTT" made over 1000hp on a MAF system (albeit a SCT components system, not OEM)

[RoadWarrior222]

Well obviously I know there's some wriggle room in the stock programming, all I'm saying is there's a limit to it, which isn't even news. Since the SMEC is virtually "black box" to us at the moment, no matter how wonderful it is for the 4cyl folks, having some method of external compensation would be nice is all. I know it's not perfect. (And do they have a charge temp sensor btw?) Obviously correctly dialled in callibrations specific to the motor are going to be the best. SD may give more at top end than MAF, my only point with all that was that you may get quicker, more linear feedback from a MAF system while experimenting, when the ECU is closed to you. You hit 200hp on a 200hp rated MAF and you know that's it, (And you get some sort of fix with a bigger MAF) you hit the somewhat elastic, poorly defined limits of our SMEC programming and you end up unsure what's really going on, you make a drastic change and get no more ponies. Did it work or not? No-one knows. For all we know there has been 250HP motor configurations running round that a cal would have uncorked. Yes I don't really know for sure what is happening with the fuel, when I get there I'll stick a 'scope on the injectors. I'm coming up with halfassed speculation based on what seems to be the case for better documented ECUs, I'll admit that. I do believe that mods that make things run such that one sensor is way more skewed from expected vs the stock VE calculations will cause "learning" of a sensor offset rather than true adaption. I hang round fuel economy forums where guys are running into sensor problems all the time, from the opposite side of things, but it's instructive in seeing how various ECUs deal with various strange inputs. These arguments are kind of getting kind of like saying that a Konigsegg is the fastest way to commute to work and an Insight is the most economical way to commute to work, so what's the point of driving a dodge? Answer: So you just damn well quit dreaming and actually get there somehow.

If I come across any '91 SMECs I'll bear you in mind Ed. The real solution is we get these suckers figured out.

[jmitch]

Quote:

Originally Posted by 87turbodance A couple years ago my buddy but a Chev 350 TPI in his firebird. He didn't know whether to go with a MAF computer or a Speed Density computer. (Early TPI motors were MAF and later TPI motors were Speed Density. The SD motors gained 5 hp).

the reason why the sd tpi 350s gained 5hp was due to no restrictions from the mas.

coming from a ford owners perspective my stock 86 gt mustang was faster than my stock 90 gt , but when i installed a performance cam in my 86 and the same cam in my 90 my 86 fell on its face while my 90 would run like a raped ape all because the computer could read the changes and compensate due to the imputs from the mas. also on dsms we use the mas translator to run gm style 3ich mas instead of our more restrictive mas. same for the conquest.
i've often wondered if there was a way to convert the 30 to mass operation. the sd system is a tough system that works great until you start changeing things. do a search on the early sd mustang drawbacks. those early sd systems were alot like the mopar setups .

[Ntrain2k]

Quote:

Originally Posted by jmitch coming from a ford owners perspective my stock 86 gt mustang was faster than my stock 90 gt , but when i installed a performance cam in my 86 and the same cam in my 90 my 86 fell on its face while my 90 would run like a raped ape all because the computer could read the changes and compensate due to the imputs from the mas. also on dsms we use the mas translator to run gm style 3ich mas instead of our more restrictive mas. same for the conquest. i've often wondered if there was a way to convert the 30 to mass operation. the sd system is a tough system that works great until you start changeing things. do a search on the early sd mustang drawbacks. those early sd systems were alot like the mopar setups .

EXACTLY!!

No one understood the ford SD code, and it was not mod friendly other than bolt ons. When the MAS cars came out, it was able to adapt the fueling for more extensive mods. This is where the fallicy came from. The ford SD code was not hacked until long after the mass air cars came out. The SD setup, when able to be programmed properly, can and is superior to the maf setup simply because of the restriction that the maf itself has in the intake path.

[RoadWarrior222]

So I ran some numbers and it seems like one can compensate about 1% increase in V.E. by fudging the charge temp sensor to read about 2.5C colder. There's probably a practical maximum of about 10% there for daily drivers. For a track car that always races in 30*C summer temps, you might be able to compensate 20%, but watch out if you get a 15C evening run. I think this probably equates to around 2 psi or 4 psi boost that can be compensated for. Meaning that if you can get it to tune in a few PSI by itself, you might get another couple out of it by faking the ChTS.

However, finding out actual V.E. before and after mods is a bit of a problem. Trying to find DIY methods for that, but only get as far as "Connect a scan tool..." bzzzt, wrong answer, only works for MAF ECU. Okay mebbe we can get/derive the stock figure out of the SMEC/SBEC with something like digital dash, but after engine mods it will be wrong.

Supposedly hotwire MAF sensor signals are 0-5V proportional to flow, so I suppose if you know the flow rating of a MAF unit you could temporarily connect it in the airflow path of your setup and read voltage off it at various RPM, purely to determine V.E. Have to correct for temperature though.

Anyhoo, need to find the values for the ChTS (IAT) to figure bias.

[RoadWarrior222]

Dammit, just figured that whether messing with the IAT helps dial in mods or not, that '87 and '88 motors with it on are getting rarer and rarer. They're all getting crushed right now. For some reason I was thinking Daytonas and LeBarons had the 3.0 in '88 too, but only the minivans and tankish n'orkers and dysentries had '88 motors. So much for finding a '87 or '88 car sometime for a project vehicle. Wonder how much different '89 and '90 stuff is, and whether it will run off an '88 cal with IAT spliced in. Well, I'd just have to see how it works on the van here first. I just got dreams of running 6-8psi off an M90 in a 'tona. Ah well, first things first.

[Shel-Game]

FWIW,MAF sensors really need to be re-calibrated when the airflow through them changes. So, while cam or head porting might not affect the flow through the MAF, simple changes like going to a cone filter will throw them off.

Also, it's actually really easy to change the VolEf table in the SMEC - even for the V6's. You just need to know what the new curve might look like...

[tkelly27]

Quote:

Originally Posted by RoadWarrior222 So I ran some numbers and it seems like one can compensate about 1% increase in V.E. by fudging the charge temp sensor to read about 2.5C colder. There's probably a practical maximum of about 10% there for daily drivers. For a track car that always races in 30*C summer temps, you might be able to compensate 20%, but watch out if you get a 15C evening run. I think this probably equates to around 2 psi or 4 psi boost that can be compensated for. Meaning that if you can get it to tune in a few PSI by itself, you might get another couple out of it by faking the ChTS. However, finding out actual V.E. before and after mods is a bit of a problem. Trying to find DIY methods for that, but only get as far as "Connect a scan tool..." bzzzt, wrong answer, only works for MAF ECU. Okay mebbe we can get/derive the stock figure out of the SMEC/SBEC with something like digital dash, but after engine mods it will be wrong. Supposedly hotwire MAF sensor signals are 0-5V proportional to flow, so I suppose if you know the flow rating of a MAF unit you could temporarily connect it in the airflow path of your setup and read voltage off it at various RPM, purely to determine V.E. Have to correct for temperature though.

Your math based on what? It's been said over and over again in this thread, we really have no idea what the ECU does with any of the sensor input it's getting. Everything I've read about the charge temp on a T2 2.2 says that it does almost nothing
Charge Air Temp Sensor
Charge air temp sen.
I've not read anywhere what it's capeable of, and that's on the well documented 2.2/2.5 cals. You also know density vs. temperature change is non-linear right?

bbzzztt! final wrong answer. Maybe you'll use a wideband and a datalogger like everyone else that's serious about tuning their engines does.

Like I said before, mass air is, at best, only a decent guess at the airflow entering your engine. If you want something that can accurately predict airflow, it's going to be $700-15,000 for a lab quality flow sensor. Automotive ones are good enough to get by, but if you're serious about making power, you still need to tune with them!!

There is a subaru shop not 5 blocks away from where I'm sitting right now. They set the subies up and modify the air fuel tables with a wideband.
"But scoobaroos are mass air, can't they just Ronco the SOB, 'set it and forget it!'"
No. It still must be tuned if you want to make the most power possible.

MAS are only reading a small slice of the air, at the point where the MAS sensor is located. Everything going on around it, and what is actually going on at the intake valve, it is completely blind to. Like Shel-Game says, you still need to tune for them, so why not go with the more accurate and less limited speed density system?

[Ondonti]

Quote:

Originally Posted by Shel-Game Also, it's actually really easy to change the VolEf table in the SMEC - even for the V6's. You just need to know what the new curve might look like...

Exactly. Ive played with the 3.0 VE curve before since its been found in a few dissasemblies I saw. Now I dont know what actual effects that curve has on how the engine runs.
As far as Im concerned SD that is tunable has no problems at all because in the end, even if your VE Curve is not perfect, you can still tune the a/f and spark to be whatever you want at various loads.

[RoadWarrior222]

Quote:

Originally Posted by tkelly27 Your math based on what? ...... You also know density vs. temperature change is non-linear right?

Now you just made yourself look silly.

edit: BTW I can only imagine you're confusing it with density vs altitude.

[tkelly27]

Density of air - Wikipedia, the free encyclopedia

Looks pretty non-linear to me. I'll help you out if you didn't get that far in math, y = 1/x is not linear.
Linear - Wikipedia, the free encyclopedia

Hey, you know, the pressure changes with altitude, think that could be the linear one? This is all so confusing to me, I dunno what to do!

Now I'd really like to know what your math is based on that you think you can safely run 4psi on a stock calibration by screwing with the charge temp sensor. Do you know what the CTS output causes what fuel enrichment value? Or were you assuming it based on a linear air density slope. Oops. Lay it out for us...

BTW, looking in D-cal, to me, the stock cal has up to a 25% enrichment in base fuel for the charge temp sensor, but that's for a 2.2/2.5, whatever that's worth to you. It's most definitely not a linear curve either, well, as non linear as you can get for only having 4 points on it.

*edit*
I'm getting snotty and off the topic, must be past my bed time, sorry. The above still stands, I'm not in the right frame of mind to put it politely, apologies.

Ondonti, do you have any links to the dissasemblies? If it can be gotten to a tune-able state, you could hook it up to a slant six or any other straight/V6 and have a nearly free programmable ECU.

[Ondonti]

No I dont the dickhead moderator there banned me because I accidentally spam'd the list.