I typed in google maf vs sd and many threads come up from tech and other forums 
Mass air system VS speed density
Thread Starter
Teching In
Joined: Aug 2009
Posts: 36
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From: Barrie Ontario
Mass air system VS speed density This may have been discussed but I cannot find it. What is the difference between a mass air system and a speed density system other than the lack of MAF? I landspeed race an 04 LSI with a mild cam and springs and it would be much simpler to duct my intake air without a MAF. What are the pros and cons of both systems and are they interchangeable?
Thanks,
Peter
02G0200
Thanks,
Peter
02G0200
personally, if your car is mainly a track star in relatively stable weather (or just a seasonal car), go speed density for the airflow.
If you do a lot of street/daily driving where the weather fluctuates a lot or is more or less year round, the MAF would probably be best.
You could also get a tuner (like Frost) to set you up with a dual tuned system that would let you switch between the two. Someone else would have to go into details on that as I've only briefly read about it.
If you do a lot of street/daily driving where the weather fluctuates a lot or is more or less year round, the MAF would probably be best.
You could also get a tuner (like Frost) to set you up with a dual tuned system that would let you switch between the two. Someone else would have to go into details on that as I've only briefly read about it.
OP, this question is better suited for the tuning section. Generally, people chose SD when the MAF ran out of measurement @ 512 g/s because there was no way to measure the higher airflow. There are other ways to run open loop without going full speed density, like open loop MAF, which ignores 02 sensors & runs on MAF feedback & fixed fueling tables. Point being that the fueling doesn't rely on air fuel measurement. Regardless, SD can be safe even in moderate temperature changing environments if tuned correctly. Key is to decide what it is you're looking for & then decide.
Thread Starter
Teching In
Joined: Aug 2009
Posts: 36
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From: Barrie Ontario
I am just looking for a simplified air intake ducting arrangement on my LS1 powered Stude. I drive it on the street and landspeed race it also. Removing the MAF would enable a larger more straight forward route to my cowl induction. I still need the engine to be docile enough to drive on the street for 8 months of the year.....but at the same time I am looking for maximum power at Maxton. Is what I am asking for attainable?
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I street drive my ride but never if the weather is going to dip anywhere near freezing. I simply ran out of room on the MAF to even think about Mass Air. Speed Density is the only way if you're going to crank the motor up without spending exotic monies. I run out of room on the MAF during street driving also and therefore I really don't see an option.
Speed Density for me.
Speed Density for me.
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Verdad Gallardo I am just looking for a simplified air intake ducting arrangement on my LS1 powered Stude. I drive it on the street and landspeed race it also. Removing the MAF would enable a larger more straight forward route to my cowl induction. I still need the engine to be docile enough to drive on the street for 8 months of the year.....but at the same time I am looking for maximum power at Maxton. Is what I am asking for attainable?
Thread Starter
Teching In
Joined: Aug 2009
Posts: 36
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From: Barrie Ontario
Ok, Thanks,
I have local tuner, but I was looking to ask intelligent questions when I install the new heads and bring it to the dyno for tuning. The more I know, the easier it is to answer Troy's questions and the more intelligent questions I can ask. Thanks again,
Peter
02G0200
I have local tuner, but I was looking to ask intelligent questions when I install the new heads and bring it to the dyno for tuning. The more I know, the easier it is to answer Troy's questions and the more intelligent questions I can ask. Thanks again,
Peter
02G0200
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
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From: So.Cal.
If you get speed density tuned properly in a steady state manner (load bearing dyno), it won't be affected by external conditions.
Just keep a wideband or two permanently installed so you can see if it ever drifts.
Landspeed racing (you mean like Bonneville?) places a very high load (high rpm in high gear) on the engine for extended periods of time... it is critical that you get the VE table correct and that you determine the best timing that avoids knock.
Be sure to get the injector tables as correct as data allows.
You could retain CL for street driving, but you don't really need to (especially if you don't run cats)... simplicity rules.
Just keep a wideband or two permanently installed so you can see if it ever drifts.
Landspeed racing (you mean like Bonneville?) places a very high load (high rpm in high gear) on the engine for extended periods of time... it is critical that you get the VE table correct and that you determine the best timing that avoids knock.
Be sure to get the injector tables as correct as data allows.
You could retain CL for street driving, but you don't really need to (especially if you don't run cats)... simplicity rules.
Have them pull it in high gear on the dyno so you can make sure the tune is good under that load...
Another thing to keep in mind is to make sure your fuel system is adequate to handle that load for a long period of time. I would have a fuel pressure gage on something like that so you can watch that it doesn't drop off any on a long WOT run. Also, I would be put a wideband in it like Joe said above, so you can watch the AFR over the run...
Another thing to keep in mind is to make sure your fuel system is adequate to handle that load for a long period of time. I would have a fuel pressure gage on something like that so you can watch that it doesn't drop off any on a long WOT run. Also, I would be put a wideband in it like Joe said above, so you can watch the AFR over the run...
Thread Starter
Teching In
Joined: Aug 2009
Posts: 36
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From: Barrie Ontario
I run an Aeromotive fuel pump and have run a fuel pressure gauge visible during my pass and I maintain 60 psi throughout the mile. I am sure I do not have a delivery problem at this time. Troy, the tuner, has fattened it up a little to make sure that it doesn't lean out on top end at WOT. Other than a mild cam and springs, it is still a stock engine. The timing is set at 29 degrees and I cannot perceive any knock, though the car is pretty noisy when it is pulling hard. We do tune the car on a dyno. I do have an air/fuel ratio meter but have never installed it on this car because I assumed when it is locked into the PCM, I would not have an issue. Am I incorrect?
To date, in the mile, my top speed is 162mph, 5th gear (.84) and 3.27 ratio on 26.5" tires.
Peter
02G0200
To date, in the mile, my top speed is 162mph, 5th gear (.84) and 3.27 ratio on 26.5" tires.
Peter
02G0200
Fuel system is good...
You are correct that once the fueling is set in the PCM, it won't change. We were suggesting the means to monitor everything due to the length of time you are running WOT. A lot different than a 1/4 mile drag race! I have tuned road race cars before, and know that long pulls can give you fueling issues. Just wanted to be sure you were gonna be ok...
What kind of fuel do you run? 29 degrees is a bit more than I normally see making best power on pump gas with a mild cam... but the dyno would tell you what it wants.
You are correct that once the fueling is set in the PCM, it won't change. We were suggesting the means to monitor everything due to the length of time you are running WOT. A lot different than a 1/4 mile drag race! I have tuned road race cars before, and know that long pulls can give you fueling issues. Just wanted to be sure you were gonna be ok...
What kind of fuel do you run? 29 degrees is a bit more than I normally see making best power on pump gas with a mild cam... but the dyno would tell you what it wants.
Thread Starter
Teching In
Joined: Aug 2009
Posts: 36
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From: Barrie Ontario
We arrived at 29 degrees on the dyno on the stock engine and came back to it again after we installed the cam and springs. We had 93 on the dyno. At Maxton, we must run race gas and the lowest we can buy is 100 unleaded. Seems to work ok. My focus is on landspeed racing and both the tuner, Troy and the dyno guy, Paul's in Jackson Mich, know that, and set the tuning to make the car last and perform.
Thanks for all the advice.
Peter
02G0200
Thanks for all the advice.
Peter
02G0200
