GuitsBoy

iTrader: (4)

The main advantage I see for SD is that you can get rid of the intake restriction (maf).

I feel that the MAF has many other advantages. I feel that fueling is far more accurate. Its easier to tune out more of my cam bucking. It handles changes in weather easily. I can pass emissions, Misfire DTCs and counts work, etc.

I have a ported MAF, so the restriction is not an issue, and since ive tuned it, my open loop tune has been far more consistant than speed density.

SmokingWS6

iTrader: (1)

Thankyou!!!

And since we can tune maf's, at least those of us that attempt it. We can now change out mafs to larger more unrestricted units, so that shouldn't be an issue.

ringram

Nice balance of opinion.

I prefer SD as stock 75mm maf is a restriction. I dont see the point with the larger ones. They still restrict flow over an open pipe, but I do understand the advantages for flexibility etc.

GuitsBoy

iTrader: (4)

This is a good way of looking at it. My biggest reason for going back to open loop MAF was that it helps aleviate cam bucking - atleast partially.

txhorns281

iTrader: (12)

Before we get all excited, I'm not sure how qualifiable what you quoted is. How can we keep enough things consistent to where you will know that it's the SD operation making the car run quicker down the track? I know in my experience, I've had both modes very well tuned, both modes making very similar dyno #s (which dyno inconsistancy alone could cause the disparity) and both modes running ballpark equally performancewise down the track and against numerous other vehicles from rolls on the street. There was never a hands-down, noticeable increase in performance. B/W either mode, I still kicked the car's asses (or lost to) that I always did, and by the same amount each time, and it was definitely not b/c of a lack of quality tuning

Usually when you have the case when one feels better than the other, it's b/c one of the modes is not properly tuned. But if you have them both inline, I'd like to see someone do a "blindfold" test and point out which is which. Come to think of it, that would be a pretty sweet deal since you'd have a 50/50 chance, though I'd be willing to wager that our "blindfoldee" wouldn't be terribly confident in deciding either way.

SmokingWS6

iTrader: (1)

In a boosted or large displacement application sometimes it becomes necessary to use a larger diameter maf if you wish to retain one due to frequency limitations. That's the main reason I bring up being able to upgrade maf's.

Personally I use a ported stock maf. I've experimented making runs with it removed and in place. I actually ran a tad bit slower with it removed, but as stated a lot of it has to do with the tune. AFR was mid 13's with it removed so that would explain the difference. It was rather cool outside and I had SD tuned it in summer heat.


BTW, just noticed you upgraded to a zo6. Any goodies under the hood?

gameover

I think you'll find the 65-70mm hole in the intake manifold more of a restriction than an 85mm MAF

ringram

... which is why I have a PT otrcai on the way

txhorns281

iTrader: (12)

LOL... this one's all for show baby... Rims, HIDs, and a few simple boltons

gameover

i meant the area behind the throttle body. but yeah Mark's CAI is a good thing

In all the testing i've seen, the difference between SD with the GTS intake pipe and the VZ 85mm MAF is zero (even on small-medium cammed cars).

if at WOT your MAP is within 1-2 of Baro then the intake is not the problem. I've seen tests that move a vac gauge along the intake and i can tell you that certainly the 70mm MAF *IS* a restriction even on a stock LS1, but the 85mm MAF moves the point of restriction to the TB and/or the intake manifold inlet section. In the pre Monaro CAI days the old style VT airbox was worse than the MAF. Who would have thought that a sub $20 airbox and creative use of a 65mm holesaw would flow better than the best HSV could come up with at the time...

Even on 4-6 psi boosted cars the 85mm MAF is not the major bottleneck.

The VZ style 85mm MAF is readily availble now in Australia, which is a totally different story to a couple of years ago when "MAFless fever" was in full swing

We regularly see s/c LS2's 6-9psi with 320+ rwkw still using the MAF. 2bar isn't far away but it's not the walk in the park the LS1 was that's for sure...

Chris...

Bink

Nah,.......you'll get the itch.
Then...the mods will start!

txhorns281

iTrader: (12)

Hey Bink, long time! I've got a bigger itch for some real estate so the car will have to be one the backburner for now! And to contribute more to this thread:

https://ls1tech.com/forums/showthrea...09#post4856709

LSs1Power

iTrader: (5)

We are seeing 13psi with my car and still running a MAF with no problems... What would SD do for me?

Red99C5

Is F1 motors driven on the street? And is the FITECH? NO and NO.

Most people go with SD for when they have reached the flow capacity of the MAF and need more air flow. IF your motor isn't flowing more CFM of air than the MAF can flow, then there is no advantage.

critter

iTrader: (9)

And some go with SD because it is the latest buzz, and having put the effort and energy into it are loath to admit they wasted their time ...

Gordy M

iTrader: (2)

During a talk with an ECM engineer, he said GM used SD for OBDI, MAF w/SD back up for OBD II, and only MAF planned for OBD III. Better practice with MAF tuning.

WS6FirebirdTA00

iTrader: (33)

Disadvantages of SD tuning (now that I have seen major weather changes on a daily driven basis)

-Lean start up with SD
-Part throttle/low flow fueling over corrected for IAT readings

Driving around now with the cam in the car, a tune on a cool day will make the car lean on a hot day (which I thought was odd) which makes it buck and it is a pain in the ***.

GuitsBoy

iTrader: (4)

Yes, this is the case with my car as well.

white2001s10

iTrader: (4)

edited due to technical errors.
my mistake.

Speartech

iTrader: (14)

Just because you didn't see it doesn't mean it isn't there.