Is anyone here making >500 hp, boosted and using mass air flow? It seems that most people give up and use speed density when making big power. I’m curious what the upper limits are of larger mass air flow sensors.
Most boosted cars have converted to standalone with a 3bar/4bar rather than going with a MAF/MAS. My 2G DSM MAF gets a bit flakey after 2200 hz so there is a MAP switchover point in my fuel management to get a cleaner reading from that. What engine management are you using for said HP?
I WAS JUST TALKING TO MIKE ABOUT THIS TODAY…
SPEED DENSITY SEEMS LIKE A MUCH BETTER METHOD…
ALTHOUGH I THINK MY BROTHER’S CAR MAKES WELL OVER 500 AND IT USES A MAF (86 GRAND NATIONAL)
Bladez is.
On 8 cylinder cars, yeah, the MAF can handle well over what the car is rated at but you can’t always adapt an LSX MAF to an import unless the fuel management specifies that you can. This is too much of a broad question, more specifics!!
all cars are different really. some you can, some you cant
I am using the stock Subaru ECU currently. I’m planning on going to a bigger turbo (likely GR35R), but I really don’t want to buy a standalone. My goal is approximately 400-450 whp. I guess the Subaru ECU can’t, or doesn’t handle speed density.
My understanding (which could of course be wrong) is that the signal from mass air flow sensors are all the same, but the range depends on the actual opening size of the sensor. If I could adapt a larger one, I’d rather do that than by a standalone ECU.
Do mass air sensors supply 0-5 volts, a frequency or both? I guess ultimately I’m trying to learn about the sensors themselves, and their differences to see what my possible options are. I don’t want to switch to speed density just because everyone else does.
You are probably better off on Buffalo Scooby or NASIOC to find those answers. Call Innovative Tuning up and talk to Mike. He can probably answer those questions for you.
here’s why you run into problems:
right now your maf reads 0-5 volts for 0-X CFM
in order to not max out the maf, you need to double it’s capacity (theoretically)
so now you still have the same number of voltage divisions, but double the amount of airflow, so you’ve cut your resolution in half.
Now, lets factor in that you are obviously going to increase your injector size as well, the same thing occurs. you lose resolution, again, probably by half.
So now you’ve cut your resolution to a quarter of what it was, so what was four points on a map is now one. This is not as critical at high RPMs, but low RPMS where much of your driving will be (if this is a street car) it will be a BITCH to get to run correctly.
In a nutshell, that’s why…
My MAF maxed out right around 450 HP on the dyno. This is on a V8 LT1 motor. The car would just die at around 5,000 RPM’s on the dyno when the MAF maxed out.
I ended up having to buy a MAF signal extender from Vortech to fix my problem. It basically “tricks” the MAF into thinking that there is less airflow going through it then there really is. It has worked great for me since then.
But, like everyone else says, speed density is probably the way to go if you wanna make tons of power with minimal hassles. I will probably consider this when the time comes for my next tune…
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Z MAFs are only good to about 500hp. But since we have dual throttle-bodies, Z owners can overcome this simply by doubling the airflow path and changing the values on the ECU.
At least on our cars, there isn’t a reason to switch to speed density. There are Zs with 1000+whp using stock MAFs.
Here you can see between the headlights, two ‘u’ shaped pipes. From the factory, the MAF would sit right in the middle where they come together. But here they split off under the bumper where 2 air filters are attached, but only one side has a MAF.
I know on 944 turbos there is a guy that put down 566rwhp and he runs MAF with the stock computer and a SMT-6. This is the same setup I run, and my MAF is rated at 600hp
With your 97 car you can always convert to OBD-I (94-95 PCM) and run a 2 bar MAP sensor to achieve speed density
Speed Density is finicky for daily driving (throttle response, milage, ect) From what I’ve read. I was considering doing a “Speed Density” tune on my car but, I was told I would not benefit from it. I’m in the process of doing a “Volumetric Efficiency” tune…should get me throttle response, better mileage, aaand maybe a few more ponies.
I hear if you have a bolt on/slightly modified car, it’s better to have a MAF system. SD would need a tune for everything thing you did, like intake, full exhaust…etc
Any truth to this?
I’ve actually found SD tunes to be SMOOTHER from mild NA applications all the way to big boosted setups (which i wouldn’t run anything BUT SD). SD does have VE tables. There are tons of tables and parameters that you can tweak. The big one chuck uses is the kpa (basically map at different loads) vs rpm. I am still learning a lot in the tuning field, but i do know i have ridden in MANY different types of LS1 cars, both in SD and MAF, varying T/C, S/C, NA, and N20, and im a believer in SD. im sure with different platforms it all changes
if i go to a more mild setup NA, i will stick with 1 bar SD
Interesting. Thanks for the feedback. It seems that there may be more than a couple ways to get this done. I like the way the Z’s work it out.
Removing the MAF has a couple benefits.
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Any time you remove a restriction in front of the turbo (the MAF is a large restriction) you decrease spool time and increase the amount of power that can be made per given amount of boost. Simply by removing the restriction you are making less work for the turbo. There are technical terms for all of this but it’s early for me.
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Speed density will allow you to run a non recirculated BOV like a good ricer.
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You remove restrictions on your setup.
Now running a MAF generally makes for much better driveability any other time you are not in full throttle but that doesn’t mean that a speed density car cannot drive well.
The only difference between OEM and aftermarket when it comes to tuning is that the OEMs have invested 10’s of thousands of man hours developing calibrations for their fuel systems where you are paying someone 4 maybe 5 hours depending on the complexity…you get what you pay for. If you are running a standalone it certainly will not be perfect like the OEM to start in -40 or +140, or drive with near perfect A/F ratios at each and every load point and possible weather condition everytime. You just can’t do it all in 5 hours etc. You will have to invest a serious chunk of change for the time to dial in YOUR setup as they are all different and importing someone elses settings will still not get you perfect.
i think you could also run twin smaller mafs that have a better resolution and average the voltage (a la skyline) this gives you better resolution, but added complexity.