MAF vs SD
Okay, I damn near spit out my drink laughing at that first sentence.
Thread Starter
Teching In
Joined: Aug 2021
Posts: 22
Likes: 4
Unfortunately this seems to be the trend even now. People are afraid to learn how to tune or learn literally anything about it, so they have no f’n clue what they’re getting. Worse, these same folks get on forums like this and try to sell how great their “experience” was when they have no clue how close their car is to exploding, or how much power they are missing out on because someone tuned their airmass to be 10:1 in PE for “safety.”
The best example perhaps is our glorious OP, who asked a complex question, involving many factors, and has yet to grace us again with his decision. He’s actually thinking he can get 550 whp out of what he has with stated planned mods. He must be assuming someone can “tune in” about another 200 bhp to get him there or something because I don’t see it. Just to go over 500 I had to stroke mine to 427 and get my compression near 12:1 N/A. Good luck OP. That costs money. Lots of it.
It’s almost like much of this information is free and even explained on YouTube and this very forum, and even this thread, but yet folks still don’t take the time to research it. They just want it now. If I was less honest I would be one of those tooners you are talking about because some of these folks might actually deserve to be taken to the bank. Call me crazy, but I think I just described a portion of the current tuner market.
The best example perhaps is our glorious OP, who asked a complex question, involving many factors, and has yet to grace us again with his decision. He’s actually thinking he can get 550 whp out of what he has with stated planned mods. He must be assuming someone can “tune in” about another 200 bhp to get him there or something because I don’t see it. Just to go over 500 I had to stroke mine to 427 and get my compression near 12:1 N/A. Good luck OP. That costs money. Lots of it.
It’s almost like much of this information is free and even explained on YouTube and this very forum, and even this thread, but yet folks still don’t take the time to research it. They just want it now. If I was less honest I would be one of those tooners you are talking about because some of these folks might actually deserve to be taken to the bank. Call me crazy, but I think I just described a portion of the current tuner market.
Thread Starter
Teching In
Joined: Aug 2021
Posts: 22
Likes: 4
Big facts here. Most people are just most people and for the lack of a better term, not horsepower nerds lol. I like going fast. I like fast cars. Driving them, tuning them, building them, etc. We’re all nerds for horsepower here. Sucks if you don’t like math because the results are horsepower in the end.
I seriously wonder at this point how the op feels about this post at this point considering he asked a “simple” question lol. Not so simple as he rightly pointed out. At this point this thread has been straight hijacked lol. I’ve seen no reply’s or questions so far. He just dropped a bomb and dipped out. Good for him. @imaswfan
I seriously wonder at this point how the op feels about this post at this point considering he asked a “simple” question lol. Not so simple as he rightly pointed out. At this point this thread has been straight hijacked lol. I’ve seen no reply’s or questions so far. He just dropped a bomb and dipped out. Good for him. @imaswfan
Thread Starter
Teching In
Joined: Aug 2021
Posts: 22
Likes: 4
MAF is better for a street car with mild mods. Really, either is fine since you can choose multiple options. There are four typical ways to skin this cat:
MAFOL
MAFCL
SDOL
SDCL
There is also blended “stock settings” which simply uses both models.
The “OL” and “CL” are “Open Loop” and “Closed Loop”, and that is simply a reference to if your O2 sensors are on or not. They are “on” in CL.
Bear in mind though that the stock O2’s get pretty inaccurate once they are above or below about one value from stoich. Simply means they don’t work so well if you are out of the 13.5 - 15.5 AFR range.
Since SD does in fact change with weather conditions, which is extremely difficult to pin down with the IAT/ECT bias, that means MAF will stay more accurate throughout the year.
SD is awesome for rowdy builds because it’s a straight forward mathematical lookup table, and whatever cell you are in will be what you tell it to be. Tends to have less issues with narly cams and turbulent slow moving idle air. Big cams reduce vacuum. but since it is a lookup table, there’s not enough corrections to keep it dead on through the year. The O2’s can make up for it, but only reliably if you aren’t outside the window mentioned above.
Hopefully that makes sense. No argument here. Do what you want, both work great if you tune them right. At a certain point though you will run out of MAF, which is why big HP cars run SD only pretty much. Though with newer generation ECM’s, the limit is pretty damn high lol.
MAFOL
MAFCL
SDOL
SDCL
There is also blended “stock settings” which simply uses both models.
The “OL” and “CL” are “Open Loop” and “Closed Loop”, and that is simply a reference to if your O2 sensors are on or not. They are “on” in CL.
Bear in mind though that the stock O2’s get pretty inaccurate once they are above or below about one value from stoich. Simply means they don’t work so well if you are out of the 13.5 - 15.5 AFR range.
Since SD does in fact change with weather conditions, which is extremely difficult to pin down with the IAT/ECT bias, that means MAF will stay more accurate throughout the year.
SD is awesome for rowdy builds because it’s a straight forward mathematical lookup table, and whatever cell you are in will be what you tell it to be. Tends to have less issues with narly cams and turbulent slow moving idle air. Big cams reduce vacuum. but since it is a lookup table, there’s not enough corrections to keep it dead on through the year. The O2’s can make up for it, but only reliably if you aren’t outside the window mentioned above.
Hopefully that makes sense. No argument here. Do what you want, both work great if you tune them right. At a certain point though you will run out of MAF, which is why big HP cars run SD only pretty much. Though with newer generation ECM’s, the limit is pretty damn high lol.
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
Likes: 179
From: Virginia
Lol I would pay a million dollars if a tuner was able to just tune in 200hp. I didnt mention it in the post, but the 550 number is all time goal, that will be after I build the motor and throw a procharger on it. I should've been more specific. And I find making posts here when im able to get responses quick from people who atleast sound like they know what theyre doing more valuable than a youtube video, but I do use both.
With a pro-charger that makes a lot more sense. 550 should be pretty easy. Just make sure with your goals, stick to them to avoid buying the wrong parts and going back later. Example is heads and cam. If your goal is boost, then build the rest around that. Otherwise you’ll end up reversing decisions and that is costly.
Well I hope we all sound like we know what we’re talking about lol. You’re right, YouTube doesn’t always have the best information, however it is out there if you know where to look.
Ok. My customer now has 3.55 gears in place of the 2.56.
We are headed to the drag strip to do more WOT testing.
I made the suggested changes to the Maf Filter and the Fuel to Wall table.
We shall see what happens!
I'll tune it SD if I have to, but that's a lot of work. And he will never go drive it like I ask him to. I won't ride with him, and I won't drive his car.......
Sure was nice when I was running a dyno.
Ron
We are headed to the drag strip to do more WOT testing.
I made the suggested changes to the Maf Filter and the Fuel to Wall table.
We shall see what happens!
I'll tune it SD if I have to, but that's a lot of work. And he will never go drive it like I ask him to. I won't ride with him, and I won't drive his car.......
Sure was nice when I was running a dyno.
Ron
The drags were 1/8 mile.
6700 in second right at the finish line.
First pass was lean both gears. Made the correction, nearly 15% did another pass.
Almost the same result. Did another correction. The maf curve was looking like a hockey stick.
Hmmm
Took the air filter off. It’s a quite small K&N right on the maf inlet. Screened 85mm
Made another pass. Picked up 3 mph……and the fuel went dead rich! Like 11:1. Was commanding 12.5:1
Did the correction again, still rich down low, but right on above 4000 or so.
Developed a small oil leak, so called it quits.
It needs a converter. Flashes to a whopping 2200 rpm.
Ran 91.5 mph, so it does show potential.
6700 in second right at the finish line.
First pass was lean both gears. Made the correction, nearly 15% did another pass.
Almost the same result. Did another correction. The maf curve was looking like a hockey stick.
Hmmm
Took the air filter off. It’s a quite small K&N right on the maf inlet. Screened 85mm
Made another pass. Picked up 3 mph……and the fuel went dead rich! Like 11:1. Was commanding 12.5:1
Did the correction again, still rich down low, but right on above 4000 or so.
Developed a small oil leak, so called it quits.
It needs a converter. Flashes to a whopping 2200 rpm.
Ran 91.5 mph, so it does show potential.
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Follow up.
We put a 3500 converter in, and a much larger air filter.
Made 3 tuning passes. I have 2nd gear and third pretty flat on fuel. 2nd is 2% lean and third is 1% rich. That’s pretty good.
First is still 10% lean. I’ll work on that next time.
From the previous week it’s improved 6 tenths of a second.
We put a 3500 converter in, and a much larger air filter.
Made 3 tuning passes. I have 2nd gear and third pretty flat on fuel. 2nd is 2% lean and third is 1% rich. That’s pretty good.
First is still 10% lean. I’ll work on that next time.
From the previous week it’s improved 6 tenths of a second.
