# MAF in front of Throttle body 05 GTO M6



## danfigg (Sep 27, 2009)

I think this issue is an important one yet no one has responded to it any thought on this issue

I moved the MAF in front of the Throttle body and found a filter (the short spectre) that fits in between the radiator and the hood closes. I did this before and got an engine light. After speaking with people I found that it is possible I put the MAF in the wrong position. This time I made sure I put the MAF in the correct position using the original hose as a reference. Well low and behold, I take it for a ride and she pulls hard and no light comes on. The way she pulls is like night and day. With the timer I pulled a 0-60 in 5.7 secs. This may not be impressive but my launch sucked as my RPM were up at 2000 RPMs and she kind of bogged as she left. But once the RPMs got around 2500 she opened right up and I could feel the power coming right to redline. A quick shift into second and I hit 60 and stop the clock. So to sum it up I start the clock first then launch and then stop the clock as she sweeps past 60 MPH. So clearly That time is not accurate. Im think it should be faster than 5.7 seconds. Any thoughts by the air flow experts are welcome. Im sure the filter im using is to small but she seems to run good and I have no way of knowing if she is running rich other than standing at the exhaust and have not notice anything like that-------------Danfigg


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## svede1212 (Nov 1, 2005)

I've seen that done before. I'd want to see the AFR as it more than likely has changed and could be an issue or maybe not. I wouldn't want to take the chance. Your gains are more than likely due to removing the elbow and shortening the flow path. The heat factor is going to suck tho. It sounds like you have 1 of the 3 things an intake does accomplished. Now if you figure out how to get a bigger filter on and get cool outside air in as straight of a path as possible you'll have an over the radiator air intake. I think I have instructions on how to do that.


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## danfigg (Sep 27, 2009)

*re*

Yes you are right you do have the instructions. I have been driving the car and it has been real hot out here in NY 85-90 plus degrees havent notice any changes in power I do have a IAT relocation so that may have alot to do with it. Doing research I did see a nice T to the throttle body with double filters on each side. under hood temp may problem though -----Danfigg


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## svede1212 (Nov 1, 2005)

A relocate doesn't change the temp of the air. It would be the same thing as adjusting the IAT timmng table if it isnt reflecting actual inlet air temp. Hotter air is thinner air and will restrict max timming to prevent detonation


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## danfigg (Sep 27, 2009)

*re*

Svede im a little confused with Speed Density and Mass Air Flow maybe you can clear things up back in the day I had an 88 mustang GT it was SD and the hot set up back then was to convert to mass air. Any bolt ons or cam changes with SD and the car ran like crap once converted to Mass air the car ran great because the mass air could compensate for the changes. So what is the story with the GM's version of mass air and why do people switch over to SD. Did you do it for clearence for your OVTR air intake to the throttle body or did you have other reasons. I know your good with HP-tuners so does SD have its benifits-----danfigg


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## svede1212 (Nov 1, 2005)

MAFs make it easier to tune a car from the manufacturers point of view and allows for variations and wear in the engine over time. It measures air flow as opposed to SD which calculates air flow based off of RPM and air pressure in the manifold (varied by local barometric pressure, source of the intake track and TB blade opening). The VE table is the "volumetric efficiency" table that has cells corresponding to RPM and and manifold pressure to make that calculation. GM's version of VE isn't the exact same thing but it's close. FWIW roughly a LS1 with a VE of 100 at a given RPM has 43 cu in of air at atmospheric pressure in each cylinder. At a VE of 50 (part throttle/part vacuum) is has 21.5 cu in at atmospheric pressure and so on. You're inputting thru tuning the computer how much air (and thus O2) is in the cylinder at any manifold pressure and RPM. It's pretty easy to do with HPT and a wideband O2 sensor.

I went SD way back 5 years ago before the latest intake because when doing a proper tune you should defeat the MAF and tune your VE tables first. Tuning the VE table is the main part of a SD tune. After doing so I liked how the car ran so much that I just left the MAF off. I also saw it as a restriction on my 80mm TB. The LS1 MAF is an effective area less than 75mm and the LS2 is less than 85mm.

IMHO the VE table should be dialed in below 4,000 RPM regardless of if a MAF is used. It will just have better throttle response because a MAF is good at steady state air flow but not quite as good at very low flow and is slower to react at throttle transition changes. 

For higher RPM how much air is getting into the manifold is important and it's funny but people get all excited about a 92mm or 102mm FAST and then stick a little LS2 MAF in front of it. You can only get thru the straw whatever goes thru the smallest restriction. A 100mm MAF can solve both the challenges of tuning for SD and not restricting flow. Tuning myself makes it just as easy to forgo that and just do SD.

The SS intake works with all 3 years of GTO and any MAF, TB, NOx plate or manifold combination.


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## danfigg (Sep 27, 2009)

*re*

well i will keep it short no real improvement with the maf in front of the throttle body I went to the track tonight and all i could get was a 13.44 once i switched back to the elbow type and bigger filter it went 13.29 at the same 105 mph also my 235-55-17's stuck like glue and i was having clutch slipage at times. So needless to say track day was a roller coaster very inconsitant. I will stay with my home made air intake and leave the idea of moving the MAF infronto f the throttlebody----Danfigg


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## svede1212 (Nov 1, 2005)

Often the increase in sound gives the perception of more power just like with a louder exhaust when there really isn't. You more than likely changed your tune with the MAF in a turbulent area as well. A lot of people have messed with different ideas and that's cool but an intake comes down to filter, flow and IATs. One of the serious GTO track guys (10 second car) logged multiple runs and found that his high flow intake only matched an OTRCAI when he pulled the headlight out to get ambient air in. He went with my intake as he didn't like taking the light out at the track every time and how that made the car look. It ended up in GM High Tech Performance magazine.


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## danfigg (Sep 27, 2009)

*re*

Im saving up soon The look of your intake is just plain mean looking. Right now I have to concentrate on what I have right now which is my under drive pulley which I bought over a year ago and my clutch. I think I have another issue going on with the SLP tuner and tire size causing the traction control to come on which might be related to clutch slippage. I cant tune for axle ratio or tire size with the SLP diablo tuner which stinks. The regular diablo you can tune for that stuff so I gotta give them a call. the trip was 120 miles round trip and at 60 MPH I averaged 16 MPG which is not correct so my milage(odometer) is off by alot. I used to get 23-26 miles to the gallon. On a full tank of gas, I can only go 280 -300 miles on the tripometer but the range distance say I can go 350 miles on a full tank-------danfigg


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## svede1212 (Nov 1, 2005)

When i got my HP Tuners I licensed it for all '04s so anybody local can get tweaks to things like skip shift and tire ratios. It was definitely a good investment for me


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## rnoswal (Dec 2, 2007)

svede1212 said:


> MAFs make it easier to tune a car from the manufacturers point of view and allows for variations and wear in the engine over time. It measures air flow as opposed to SD which calculates air flow based off of RPM and air pressure in the manifold (varied by local barometric pressure, source of the intake track and TB blade opening). The VE table is the "volumetric efficiency" table that has cells corresponding to RPM and and manifold pressure to make that calculation. GM's version of VE isn't the exact same thing but it's close. FWIW roughly a LS1 with a VE of 100 at a given RPM has 43 cu in of air at atmospheric pressure in each cylinder. At a VE of 50 (part throttle/part vacuum) is has 21.5 cu in at atmospheric pressure and so on. You're inputting thru tuning the computer how much air (and thus O2) is in the cylinder at any manifold pressure and RPM. It's pretty easy to do with HPT and a wideband O2 sensor.
> 
> I went SD way back 5 years ago before the latest intake because when doing a proper tune you should defeat the MAF and tune your VE tables first. Tuning the VE table is the main part of a SD tune. After doing so I liked how the car ran so much that I just left the MAF off. I also saw it as a restriction on my 80mm TB. The LS1 MAF is an effective area less than 75mm and the LS2 is less than 85mm.
> 
> ...


What is SD? I have a 2005 GTO, LS2 with an over the radiator air filter, can't remember from who right now. I have always thought my car was running rich. Black exhaust, not blowing out rich black smoke but black sooty residue. I don't have any codes and have a Diable tuner. The car runs well, I have JBA shorty headers, an X-pipe and Gibson rear mufflers, so I am getting the air in and out pretty good, but just seems rich. 

Of course maybe the days of a light grey exhaust are gone with cats and efi. But I like the idea of not having the MAF sensor in the air stream if possible. So, maybe a little more in depth description and how to tune for that would be nice. I don't have a wideband though and that might make it hard if not impossible to fine tune it. Let me know please.

Thanks

Russ


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## Falco21 (May 11, 2010)

SD stands for Speed Density.


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## svede1212 (Nov 1, 2005)

A tuning suite and wideband make it pretty easy to SD tune. You drive, log AFR error percent and then multiply that to the VE table to correct AFR fueling. The VE table in SD tells the computer how much air should be in the cylinder under different RPM and manifold vacuum levels. It's it's rich in that cell then a lower VE value there tells the computer there's less air and to put less fuel in. It will then run leaner there. With a hand held it's a lot messier as you don't get to see all the tables and you have to go by fuel trims. I'd only do a SD tune with the right stuff.


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