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speed density or maf tune

This is a discussion on speed density or maf tune within the Forced Induction forums, part of the LSx Technical Help Section category; Im going to be running a 373 stroker ls1 twin turbo and have conflicting opinions over speed density or maf ...

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    Junior Member 65ls1's Avatar
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    1965 chevelle 2drht ss

    speed density or maf tune

    Im going to be running a 373 stroker ls1 twin turbo and have conflicting opinions over speed density or maf tunning the car is going to be driven on the street and I wish to achieve 900-110 rwhp 96lb injectors with stock ecu and injector driver for low impedence, 3 bar map

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    NASCAR Go Fast, Turn Left ntimid8r's Avatar
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    I personally feel the maf is better because it has the ability to adjust itself to the conditions. Whereas SD is a fixed setting, so any change in atmospheric pressure (altitude mainly) now alters the amount of air going into the motor. Also, SD tune was yesteryears technology. But some guys swear by the SD tune for their motor. I've never ran on a SD tune.

    Let me know how that motor installation goes. I've got a '65 el camino that I'm going to be putting my stock LS1 and 4l60e into. I've only seen one write up specifically for a '65.

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    Junior Member 65ls1's Avatar
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    1965 chevelle 2drht ss

    Maf Tuning

    YOU SHOULD CHECK OUT STREET AND PERFORMANCE THEY HAVE ALL THE DOES AND DONTS OF THE INSTALL AS FAR AS MY TUNING ISSUE iM NOT SURE WHICH IN MY SITUATION WHICH IS BEST i UNDERSTAND YOUR POINT THOUGH THE MAJORITY OF THE LOCAL TUNERS IM INTERESTED IN TUNING MY
    CAR ALL SAY SPEED DENSITY BUT DONT EXPLAIN WHY

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    Junior Member 65ls1's Avatar
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    sorry for all caps keyboard stuck

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    NASCAR Go Fast, Turn Left ntimid8r's Avatar
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    Quote Originally Posted by 65ls1 View Post
    YOU SHOULD CHECK OUT STREET AND PERFORMANCE THEY HAVE ALL THE DOES AND DONTS OF THE INSTALL AS FAR AS MY TUNING ISSUE iM NOT SURE WHICH IN MY SITUATION WHICH IS BEST i UNDERSTAND YOUR POINT THOUGH THE MAJORITY OF THE LOCAL TUNERS IM INTERESTED IN TUNING MY
    CAR ALL SAY SPEED DENSITY BUT DONT EXPLAIN WHY
    Yeah, Speed and Performance is the one write up that I've seen. But they seem to have it all figured out. I was looking at getting their motor mounts and fuel tank for sure. The rest I'll have to see where I end up.

    Here's a good article that explains the basics between the two. But I think it's just down to preference. Whose your tuner for this? Please don't say strictly performance....that guy tried ripping me off.

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by ntimid8r View Post
    I personally feel the maf is better because it has the ability to adjust itself to the conditions. ....


    too bad it can't 'adjust' to all of that air. Go SD once the MAF is maxed out. This happens somewhere around 500rwhp. Your factory computer is blind to boost; need a nice 2 or 3 bar OS, ESPECIALLY with the setup you are planning.

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    NASCAR Go Fast, Turn Left ntimid8r's Avatar
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    Quote Originally Posted by Frost View Post
    Go SD once the MAF is maxed out. This happens somewhere around 500rwhp.
    The LS6 MAF can go way above that. That way the motor can still work with whatever air flow comes through, unlike SD. SD is okay but leaves you stuck with certain air flow parameters.

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    Junior Member 65ls1's Avatar
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    1965 chevelle 2drht ss

    Tuning

    Lapd there otherwise known as la performance division for tuning they tuned my friends tt gto ats turbo kit.

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by ntimid8r View Post
    The LS6 MAF can go way above that. That way the motor can still work with whatever air flow comes through, unlike SD. SD is okay but leaves you stuck with certain air flow parameters.

    Hey guy, the limit is the PCM here, not the MAF. The PCM can use up to about 512g/sec and that's it... doesn't matter if the MAf freq goes up past 14kHz, it's just ignored.

    I don't even know what that last sentence means... You can run closed loop SD and have trim correction ya know. Sounds like you may not have a lot of experience with this (sorry if that sounds arrogant).

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    Junior Member 65ls1's Avatar
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    Speed Density

    Frost can I still use the stock 2000 camaro pcm with new operating system they suggested 2002 os with hp tuners

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    NASCAR Go Fast, Turn Left ntimid8r's Avatar
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    Quote Originally Posted by Frost View Post
    Hey guy, the limit is the PCM here, not the MAF. The PCM can use up to about 512g/sec and that's it... doesn't matter if the MAf freq goes up past 14kHz, it's just ignored.

    I don't even know what that last sentence means... You can run closed loop SD and have trim correction ya know. Sounds like you may not have a lot of experience with this (sorry if that sounds arrogant).
    You're right.....I'm not an expert on tuning.....but I do know the difference between a maf tune and sd tune. I'll still maintain my opinion between the two. No knocks against you bud.

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by ntimid8r View Post
    You're right.....I'm not an expert on tuning.....but I do know the difference between a maf tune and sd tune. I'll still maintain my opinion between the two. No knocks against you bud.

    No knocks taken, I just want folks to understand the difference in the two.

    Realize that once the MAF maxes out, you are forced into an area that is PURELY speed density, and unlike a custom SD tune, your setup will NOT see any extra boost nor be able to fuel for it.

    I have an HKE built shortblock, TEA heads, and custom cam and a front mount 76mm GTS. I run 17psi right now on pump gas and meth and the car should be making in the mid-high 700s to the wheel. I say should, because it's my own car and is totally tuned on the street, which is where it is run. I have run both a MAF tune and 2 bar. The two bar makes more power and there is no way to get around that. Here is why: Once the car hits about 9psi, the MAF is maxed totally out. Here is the rub, on a supercharged car, boost is ALWAYS tied to engine RPM, so table cheating past a maxed MAF is easy and works well, since it will always make X psi at X RPM. My turbo though, doesn't even start to spool hard until over 4K RPMs in first gear, yet in 4th gear, I can make 17psi by 3K RPMs easy. So here is why the MAF sucks for this... once I pass about 9psi (again where it maxes out) I have to have enough fuel in the tables for 17psi at all RPMs to keep the engine safe. So basically the car must get the same amount of fuel at 10psi as it does at 17psi since the MAF is tanked and I can't see boost like this with the PCM. My progressive methanol makes this liveable, but not by PCM alone. A 2/3bar SD OS is great; we can see boost and fuel properly for it all over the place. I could be seeing 1-2-3-4-5-8-or 10psi (or more) at 5KRPMs and the fueling is always metered properly. You just can't do this with a MAF.

    On the subject of weather (a concern you noted). Your fuel correction comes primarily from your narrowband O2s and fuel trims that are based on their feedback. You can run closed-loop speed-density and the PCM will constantly correct all idle and cruise tables to acheive 14.6-7:1 and good gas mileage. Don't confuse open or closed loop with speed-density or MAF metering, they are entirely seperate processes.

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by 65ls1 View Post
    Frost can I still use the stock 2000 camaro pcm with new operating system they suggested 2002 os with hp tuners
    Absolutley. A 2K PCM can just be flashed to a 2K1/2K2. Some f-body guys dont like that route because the VIN in their PCM will have to match up with a 2K2, you don't have that worry with your swap

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    Junior Member 65ls1's Avatar
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    twin turbo tune

    Thanks for the in depth explanation Im starting to grasp what you are saying.The problem is I get so much conflicting info from several sources its hard to make heads or tales out of whats the right way and the wrong way.The wrong way can just get costly and agervation.Do I even need to install a maf or not at all just iat,map,vss,ect,2 02's from 2k camaro?Whos harness will achieve may application. Turbo 400 trans will need to add vss and cable drive for speedo?Thanks!!

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    Member Benner's Avatar
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    I personally run Speed Density with my car, mods are in the sig. The way my tuner explained it to me is that it's much easier to tune a car that's cammed with SD over MAF. The car had Speed Density when I bought it but I had it retuned. The only problem I've ran into is start up when its in the single digits outside but that doesn't have to do with the SD tune. It's Loop settings.
    98 FORMULA 6Spd, Zr1 Wheels,
    224/228 .591/.591 113LSA Cam, LS6 Oil Pump,
    918 Valve Springs, Heads Milled .010",
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    MagnaFlow Catback, Ls7 Clutch/Flywheel,
    Hurst Billet/Plus Sifter, BMR Rear Suspension,
    Eibach Pro-Kit
    365 RWHP 373 RWTQ

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by 65ls1 View Post
    Thanks for the in depth explanation Im starting to grasp what you are saying.The problem is I get so much conflicting info from several sources its hard to make heads or tales out of whats the right way and the wrong way.The wrong way can just get costly and agervation.Do I even need to install a maf or not at all just iat,map,vss,ect,2 02's from 2k camaro?Whos harness will achieve may application. Turbo 400 trans will need to add vss and cable drive for speedo?Thanks!!

    Every swap I have done or worked on has had a modified/stripped factory harness, so I'm not sure which aftermarket piece would work best.

    I encourage you to not just take my word, but ask for yourself. Make an account over at HPTuner's forum and post the question in the Gen III section. Title it something like "2/3 bar SD or MAF tune?" and then describe your application/setup as you did above and see what the other tuners there tell you.

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    NASCAR Go Fast, Turn Left ntimid8r's Avatar
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    Quote Originally Posted by Frost View Post
    No knocks taken, I just want folks to understand the difference in the two.

    Realize that once the MAF maxes out, you are forced into an area that is PURELY speed density, and unlike a custom SD tune, your setup will NOT see any extra boost nor be able to fuel for it.

    I have an HKE built shortblock, TEA heads, and custom cam and a front mount 76mm GTS. I run 17psi right now on pump gas and meth and the car should be making in the mid-high 700s to the wheel. I say should, because it's my own car and is totally tuned on the street, which is where it is run. I have run both a MAF tune and 2 bar. The two bar makes more power and there is no way to get around that. Here is why: Once the car hits about 9psi, the MAF is maxed totally out. Here is the rub, on a supercharged car, boost is ALWAYS tied to engine RPM, so table cheating past a maxed MAF is easy and works well, since it will always make X psi at X RPM. My turbo though, doesn't even start to spool hard until over 4K RPMs in first gear, yet in 4th gear, I can make 17psi by 3K RPMs easy. So here is why the MAF sucks for this... once I pass about 9psi (again where it maxes out) I have to have enough fuel in the tables for 17psi at all RPMs to keep the engine safe. So basically the car must get the same amount of fuel at 10psi as it does at 17psi since the MAF is tanked and I can't see boost like this with the PCM. My progressive methanol makes this liveable, but not by PCM alone. A 2/3bar SD OS is great; we can see boost and fuel properly for it all over the place. I could be seeing 1-2-3-4-5-8-or 10psi (or more) at 5KRPMs and the fueling is always metered properly. You just can't do this with a MAF.

    On the subject of weather (a concern you noted). Your fuel correction comes primarily from your narrowband O2s and fuel trims that are based on their feedback. You can run closed-loop speed-density and the PCM will constantly correct all idle and cruise tables to acheive 14.6-7:1 and good gas mileage. Don't confuse open or closed loop with speed-density or MAF metering, they are entirely seperate processes.
    Okay, I guess since I was running on a stock motor with a max of 9psi boost I didn't have the issue you mention. Apparently I will need to change my views of the sd tune since my new motor will be in the 12psi range. I like the information about the closed-loop sd tune for good idle and normal drive ability. My car is a street first, strip second so having nice idle and manors is important.

    Thanks for sharing the information. Despite your arrogance, you've gained my confidence in your abilities.

    --Rich

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    TunedbyFrost.com Tuner Frost's Avatar
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    Haha

    Some other tuners will disagree (and some will agree) but if you have a blower, you can get by on the MAF without the issues noted above since your boost is ALWAYS fixed against RPM (unless your belt slips, but it's ok cuz you will just go rich). So if you max out your MAF by 4800 or so, you can add fuel via the PE table which is RPM based. The big problem with the turbo is their ability to make all ranges of boost at different RPMs depending on load.

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    NASCAR Go Fast, Turn Left ntimid8r's Avatar
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    Well now you have me interested in sd tune for my blower application.

    So I'm wondering if I'm leaving hp on the table by using a maf. My new motor is a 383 stroker using 317 ported heads and a P1 procharger.(Motor just built and haven't ran in car yet) Also I got a alkycontrol meth kit to help with cooling too.

    Do you think sd tune is better for my application? Or can the maf provide all the power available in a good tune and no need to change teams?

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    TunedbyFrost.com Tuner Frost's Avatar
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    Well as I said, with a blower you can get by tuning the MAF until it is maxed and then working the PE table, which fuels at WOT against RPM. Usually if a blower car doesn't max until 5K or so, I will leave it on the MAF. What happens is, up top, instead of leaving it at, say, 11.5:1, I will leave it at 11.2 or so :1 because fueling at WOT past the MAF will change a little with outside temp. If you tuned past the MAF for 11.5:1 in the summer, it would get a bit leaner as the air got cold outside. That is why it would be left at like 11.2:1, to give it a little room. You could make a little more SD, as you can maintain 11.5:1 regardless of temp (since that OS can SEE boost) but it's not going to be like if you had a turbo. Also keep pricing in mind since SD takes longer than a MAF tune. For me personally, with a blower car, it depends on where the MAF maxes as to which approach I take for tuning.

    For turbo over 500rwhp or so, SD is a must for accurate consistent fueling.

    Oh yeah, I run alkycontrol too and recommend it to all of my tuning customers that ask about meth. What a great system!. You can actually use the 2bar MAF that came with your alky kit in place of the factory MAP and rather than buying a new unit for 2bar tuning.

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