Speed Density Vs. MAF
06-10-2001, 10:00 AM
#1
Speed Density Vs. MAF
I know Speed Density is better. here is my question. I blew my 305 TPI with MAF. If I get an L98 with Speed Density will I have to change anything besides my chip?
------------------
1986 Trans Am, T-Top, 305 TPI, Flowmaster 80 series. Much more to come in July.
[*]Sound System: Dual 12" Ground Zero Nuclear Series 900 watt RMS subs in custom box made to fit the rear well, Only 500 watts running them though, Pioneer Head Unit and Rockford Fosgate wiring.
AOL screen name= madbiker1
------------------
1986 Trans Am, T-Top, 305 TPI, Flowmaster 80 series. Much more to come in July.
[*]Sound System: Dual 12" Ground Zero Nuclear Series 900 watt RMS subs in custom box made to fit the rear well, Only 500 watts running them though, Pioneer Head Unit and Rockford Fosgate wiring.
AOL screen name= madbiker1
06-10-2001, 01:57 PM
#2
Supreme Member
Join Date: May 2001
Location: Amelia, OH, USA
Posts: 1,118
Likes: 0
Received 0 Likes
on
0 Posts
I always wondered why in 85-90 they were MAF, and 91-95 they were SD, but for some reason GM switched back to the MAF.... Now why would they do that if speed density is better? I think I know, it's becuase it is not better. Dont waste your money on the swap, buy some good heads and get about 60 HP 70 trq for about half of the headache!
06-20-2001, 09:59 AM
#3
TGO Supporter
Join Date: Jul 1999
Location: The Bone Yard
Posts: 10,907
Likes: 0
Received 3 Likes
on
3 Posts
Car: Death Mobile
Engine: 666 c.i.
Check out the DIY Prom and look for Grumpy's post on MAF vs SD - The definitive answer.
The MAF system on Thirdgens is not the same as a 4th Gen. The 4th Gen system is light years ahead of anything on any 3rd Gen and does not have the 255 gm/sec air flow limitation in the eprom.
To summarize Grumpy's article (and he has worked a lot on both), MAF is better at "constant flow"...like cruising on highway and does not need to be adjusted for an increase in displacement. However, on larger motors like 383s (or bigger), they do max out the MAF sensor at fairly low rpms. Also, some people can't stand the expensive part when it goes. The MAF is a restriction but not that noticeable on moderate HP engines...it only poses a restriction at high HP...but then you have other problems like the 255 gm/sec limitation.
SD is more "reactive" and responds instantly to changes. It needs to be modified (PROM) to handle larger displacements, but it can be adjusted for larger motors. It does have a cleaner intake, but again, this is only noticeable on higher HP motors.
Neither work properly with a "power adder", though they can be "cludge" to add more fuel under boost conditions...but its a "shot in the dark" and requires a lot of testing to get the right amount of fuel.
The ARAP.BIN for the 89 MAF cars is the best starting point for a MAF car and has the MAF scalar tables setup pretty well. That is the key to good overall performance on a MAF car. So far, I have not found a need to adjust the MAF scalar tables for the ARAP.BIN on the few cars I have helped install this BIN on their eprom.
SD cars do require a fair amount of "playing" with the VE tables to get the BIN right. While it is a bit time consuming, it is very easy and straight forward. I personally prefer the SD setup because I can precisely setup the VE table to a specific load/rpm range...the MAF is more global and does not attain the same precision as SD.
But, either is way better than what you get stock. Getting 128/128 is key to getting a good running motor that performs well under most conditions. For WOT, you need to test, test and test. Forget using the O2 sensor...it is TOO inaccurate and was never designed to be used as a tuning aide. It is strictly a switching device designed to work around 450 mV to attain 14.7:1 @ closed loop....nothing more.
The MAF system on Thirdgens is not the same as a 4th Gen. The 4th Gen system is light years ahead of anything on any 3rd Gen and does not have the 255 gm/sec air flow limitation in the eprom.
To summarize Grumpy's article (and he has worked a lot on both), MAF is better at "constant flow"...like cruising on highway and does not need to be adjusted for an increase in displacement. However, on larger motors like 383s (or bigger), they do max out the MAF sensor at fairly low rpms. Also, some people can't stand the expensive part when it goes. The MAF is a restriction but not that noticeable on moderate HP engines...it only poses a restriction at high HP...but then you have other problems like the 255 gm/sec limitation.
SD is more "reactive" and responds instantly to changes. It needs to be modified (PROM) to handle larger displacements, but it can be adjusted for larger motors. It does have a cleaner intake, but again, this is only noticeable on higher HP motors.
Neither work properly with a "power adder", though they can be "cludge" to add more fuel under boost conditions...but its a "shot in the dark" and requires a lot of testing to get the right amount of fuel.
The ARAP.BIN for the 89 MAF cars is the best starting point for a MAF car and has the MAF scalar tables setup pretty well. That is the key to good overall performance on a MAF car. So far, I have not found a need to adjust the MAF scalar tables for the ARAP.BIN on the few cars I have helped install this BIN on their eprom.
SD cars do require a fair amount of "playing" with the VE tables to get the BIN right. While it is a bit time consuming, it is very easy and straight forward. I personally prefer the SD setup because I can precisely setup the VE table to a specific load/rpm range...the MAF is more global and does not attain the same precision as SD.
But, either is way better than what you get stock. Getting 128/128 is key to getting a good running motor that performs well under most conditions. For WOT, you need to test, test and test. Forget using the O2 sensor...it is TOO inaccurate and was never designed to be used as a tuning aide. It is strictly a switching device designed to work around 450 mV to attain 14.7:1 @ closed loop....nothing more.
Thread
Thread Starter
Forum
Replies
Last Post
BumpaD82
Tech / General Engine
37
02-26-2016 02:57 PM
MikkoV
TPI
2
09-09-2015 04:25 PM
