Omega Doom

iTrader: (2)

Ok my tuner wants to try a SD tune on my car and will actually do both to see whats better but he says along with alot of people on here seems to believe that the SD tune is a better tune cause' you remove the MAF restriction? it doesn't seem like that much to begin with but is there really a benefit to going to a SD tune? I don't care if there is RWHP and RWTQ to gain but since I'm new to the LS1 world I want to gain as much knowledge as I can! I came from the Stang "blue blood" side and the MAF computer is way more adjustable then SD and the ford computer doesn't have to be tuned everytime you throw a mod at it! it learns it and adjust itself! but the GM computer doesn't seem as smart? so LS1 brother's enlightnen me!

Camaro01SS4life

iTrader: (4)

Try out this site:
http://www.carcraft.com/techarticles...ion/index.html
Very good read...I am sure this will answer all of your questions if not all of them...

Kev

Omega Doom

iTrader: (2)

thanks!

foff667

iTrader: (2)

There was also a very good discussion on this topic that is now stickied at the top of this section https://ls1tech.com/forums/pcm-diagnostics-tuning/509481-advantages-disadvantages-sd.html

BlackScreaminMachine

iTrader: (17)

I read gameover's post and it made alot of sense. I do have knowledge of SD tunes from older cars.

Omega Doom

iTrader: (2)

my tuner chris marsh says he will try both back to back and see which does better on my car? so stay tuned?

flyinZ

iTrader: (15)

Every tuner that I've talked to (shop tuner of various site sponsors) have always recommended using the MAF. Why is that?

Omega Doom

iTrader: (2)

good question? it could be lack of knowledge or experience?

RedHardSupra

iTrader: (1)

no, SD is just difficult to get right. MAF is trivial to do. however, LSx computers work in a strange SD/MAF hybrid, it's not a pure MAF system, so adjusting MAF alone will only result in confusing the computer even more.

1fastTransAm

iTrader: (6)

The understanding that I have is: (I AM NOT A TUNNER just whats been explained to me)

1- there is no difference between SD or MAF tunes as far as power goes until u are above 1k hp range
2- SD is off of Trottle response.
3- SD without a MAF looks cleaner.
4- MAF is more responsive with a daily Driver.

Omega Doom

iTrader: (2)

interesting?

SSpdDmon

iTrader: (10)

My PoV....

MAF and SD are just two different ways to skin the same cat. For power purposes, it means jack **** whether you're tuned with or without a MAF. It's all about AFR. You either get the PCM to provide the optimum AFR or you don't. Just like spark, you either run the right timing or you don't (and you leave potential gains on the table).

SD is simply a calculation using constants and variables determined by several sensors. MAF is simply measured airflow that gets filtered and put through a different equation. They both calculate fuel. The arguement has been "consistency in various driving conditions is usually what sets them apart." Truth is IMO, you can get both pretty close....but I don't think there has been any empirical evidence to support one being better than the other.

ringram

Wrong on a few counts.
SD is based on Manifold pressure, intake charge temp and engine efficiency. Throttle has no direct relevance in the calculation.

MAF only has no power difference if the MAF itself is not restictive (ie crap stock 75mm choke), also the MAF/ECM cannot see more than 512g/sec of air so has a natural limit well below 1000bhp, more like 500!

SD is more responsive as maf is a heated filiment which is located outside of the intake, it takes time to react and measure. SD is calculated from intake variables and is more responsive to low rpm throttle changes. that why the stock PCM does not use MAF soley until over 4000 RPM!

Omega Doom

iTrader: (2)

I'm learning as I read! thanks guys!

gametech

iTrader: (1)

There are a few legitimate reasons to switch to SD only, but they all involve heavily modified motors. The most common is boosted engines. They easily max out the maf. Another would be enormous cams with ridiculous amounts of overlap that can cause too much reversion for the maf to be tuned properly at idle. In most other cases I wouldn't bother changing to pure SD. I ditched the maf on my GTO because it was maxed out, but I am keeping it on my boosted silverado even with the 2bar map sensor on it, because the 4.8 still doesn't max it out.

joecar

You don't need any reason to switch to SD only... you just do it if you want to.

PowerShift408

iTrader: (44)

The stock MAF has been proven far beyond 500 rwhp. The C5R race cars used a MAF... so just think about it. Only times that I would recommend SD is with a huge cam with tons of overlap like previously stated, or forced induction applications that cause the MAF to go over it's 512 g/sec limit. From what I've seen, you can still be under that limit with 8 psi of boost or less, but obviously, that depends on the situation. Just my 2 cents.

Frost

iTrader: (45)

uhhh 500rwhp IS right at the 512g/sec limit, and it's damn-sure a hard limit.

ramairws6

iTrader: (33)

If this happens to be where the maf is at it's limits(500 RWHP)I'm starting to waunder if this why my car is pulling timing when I floor it?We have finally narrowed the problem down to the maf so I put a brand new one on and it still does it.It's also tuned for the bigger maf in my PCM so the only other thing I could think of is I'm exceding my maf limit somehow?Traver

SSpdDmon

iTrader: (10)

At the track yesterday, my buddy logged his run with my software. At the lights after his burnout, his IAT was 126*F when the tree dropped. By the end of the track, it was down to 91*F. It was pulling upwards of 5* of timing because of this.

For his next run, I hooked up an extension and zip-tied an IAT sensor just above/behind the washer fluid tank. IAT's after the burnout were 88*F and less than 86*F at the end of the run. No timing was pulled.