tranb000

I have a stock bottom end ls1 with a d1 procharger. Wondering if i should do a speed density tune. The car has a stock maf right now. Its more of a street car to me with some strip passes. Just wondering if speed density is how i should have it tuned this spring.

Sales@Tick

iTrader: (3)

No doubt about it, SD is the only way to go.

silversweetZ

iTrader: (11)

What are the advantages for an SD tune vs MAF with him having a stock bottom end? Just curious, i'm in the same boat.

NightmareTA

iTrader: (20)

I made 563 rwhp on a stock LS1 MAF on a turbo 5.3 engine. Car drives great. How is speed density so much better??

I'd say if your AFR is where it should be and the car drives good, keep it MAF. In the end, MAF will compensate for temp changes, speed density won't.

ramairetransam

iTrader: (18)

My friend just did 558 613 on the stock maf d1. Cam. Meth. Stock heads. 107k motor stock bottom end. The Maf had to be scalled

ddnspider

iTrader: (26)

There's no reason NOT to keep the MAF unless you're maxxing it out or running some massive cam. Better drivability, accounts for temp change better, and is more accurate.

qqwqeqwrqwqtq

Negative on that. There are a few hundred threads on the subject (search anyone??) so no need to post misinformation.

On a 4th gen it's very easy to max out the stock MAF sensor which means any additional boost/airflow and your PCM commands no more additional fuel.

Tune something SD however and you can run 0-30lbs of boost, change it on the fly and fueling remains perfect at every boost level. Yes, and even if the temperature changes.

67Firebird455

iTrader: (27)

Great post from a master in the game. Thanks for clearing that up, I'd been throwing around the idea of using my a truck MAF I pulled off of my tahoe.

NightmareTA

iTrader: (20)

The only places that say you can only make "X" amount of power on an MAF are the guys that don't know how to tune an MAF. My tuner has made 700+ RWHP on a stock unported LS1 MAF. An MAF will always run better on a street car than speed density. Theres a reason most car manufacturers use an MAF for the main tune but "limp" back to a speed density tune if the MAF fails.

Both work well, I'm not denying that, but I personally have always liked MAF tunes over speed density.

MUSTANGBRKR02

iTrader: (91)

Properly tuned SD car you could never tell the MAF wasn't there.

LS1-IROC

iTrader: (4)

And that's the problem right there. I think alot of guys get SD tunes that aren't done well by the tuner and they blame the fact that there is no MAF in the system.

JAX04

iTrader: (17)

FO SHO

ddnspider

iTrader: (26)

Can you ellaborate on this? Where in the ECU does it compensates for temp with a speed density only tune? Or does this require a custom OS? I've looked and only see the IAT vs. spark table. I havent seen any table that impacts commanded A/F based on outside air temp.

Sales@Tick

iTrader: (3)

Pretty sure CLSD is what he is referring too as it still utilizes the O2's to correct for temp and barometric changes.

ddnspider

iTrader: (26)

Okay, but if you have negative LTFT's before going WOT just cruising around, then you are not adding fuel during WOT. Or is the assumption that you will have positive LTFT's due to the denser air just cruising around, which will be added during WOT?

chasgiv3

iTrader: (1)

Seems silly to me to use Outside Air temps when your motor only cares about Intake Air temp. Changes to outside air will affect IAT and therefore environmental changes will be accounted for. Use your IAT's.

Now where does having a MAF help you in any way? Severe elevation changes can be one place where a MAF (assuming it can handle the flow you're throwing at it) can help you have a nice tight tune. The MAF also helps with understanding the change in flow based on humidity also. But I know plenty of Road Race guys using speed densitiy tunes and the difference in tune is negligible according to them from full rain to desert dry.

I've only heard of Harlan running a MAF that can handle big power (1000RWHP) but he had his own GM custom code in there since he worked for GM with some custom MAF's.

chasgiv3

iTrader: (1)

Oh I use a custom OS so depending on year and model it may not be there.

ddnspider

iTrader: (26)

Are you saying there is an IAT vs A/F table in the custom OS? That is exactly what I've been asking, where is the temp compensation fueling table as I've only seen IAT vs spark.

chasgiv3

iTrader: (1)

Click on the link.

http://www.hptuners.com/forum/showthread.php?t=435

ddnspider

iTrader: (26)

I don't suppose that table exists in efi live?