SD or MAF (yes I've searched!)
 

Hi everyone,

Maybe I'm just really dense, but I've searched this site and others and I'm still confused, - SD tune or MAF? I see the advantages of a SD tune (and like it!), and a MAF but what are the dis-advantages? Specs on my build - 5.7 LS1, JE pistons (10.6 CR), eagle rods, Comp cam 54-458-11 and supporting hardware, ported 799's, LS6 intake, long tube "swap" headers, all being stuffed in a light weight 944. 80% street driven, with some road race track time. I want to start with a "tuned by Frost" ECU (mail order...I know it sounds scary, but lots of great reviews!!) to get it close then final tune on a dyno after a few 100 miles to break it in. Comments or advice is welcome and appreciated!

Cheers,
Gord.

A good MAF tune will be more versatile in severe weather or altitude changes and with the ls6 intake a GM 85mm MAF with a Saxon screen will not be an airflow restriction.

The biggest benefit to SD for your setup would be giving you more options for air ducting routing since you don't have to worry about turbulence affecting MAF readings.

If you are staying N/A keep the MAP/MAF hybrid that GM uses. It's the most versatile and accurate throughout different weather and altitudes. FI usually drops the MAF because it simply cannot measure the flow.

I like to run OL MAF. It's simple & easy to modify fueling.

I ran closed loop and loved it. Then again, I live 26' above sea level, and didn't have any plans of visiting the Rocky Mountains...

Can you get your fueling to be leaner than say the 14.7 CL always goes for this way?

Oh boy, now I'm more confused. I live in Nova Scotia, 95% of my driving is 0 to 400ft. Our highest peak is 1400ft! and I've never been there! Leaning to SD at the present time...

Why not run MAF, and just drop it to SD at WOT?

I had Frost do my SD tune via mail order and it turned out great. I have much better throttle response and I can ditch that MAF and run a 4" tube from my lid to my TB to fit my FAST 102 setup, resulting in no restriction. Otherwise I would need to run a 100mm MAF which is first pretty expensive for just buying the part and the tuning cost is the same as tuning for SD if not more. To me it makes more sense to run a SD setup with something like my setup where the MAF even in the 85mm could be a restriction because your lid, TB, and intake are all 104/102/102mm. IMHO the benefits of SD outweigh the cons. I live at 300' sea level or lower around where I am though so that may make a difference.

Yup. I run 16.5:1 for normal driving to save fuel & have gotten up to 33 MPG highway.

You run that lean all the time under a certain rpm and throttle position or just on light cruise?

I do the same under 3000 rpm or so and up to about 0.48 grams/cyl. Have a look at some of the stock holden tunes with lean cruise enabled (VX/VY LS1) to get an idea of what is safe. I can get under 8L/100km on the highway.

Anyway thread jack... an 85mm maf would do you well with that setup, or SD. I find maf more accurate though, copes with heatsoak and changing temps better. That IAT/ECT bias and getting an accurate IAT reading in the first place is the thorn in the side of SD tunes.

Your LS6 intake has a ~75mm neck, so an 85mm maf won't cost much power. If going FAST 102 etc then SD makes sense IMO.

Because at certain power levels (which I've achieved) the MAF "itself" becomes the restriction in the intake tract.

Running SD here. I have a pretty big cam and 102mm Fast and didn't want any restrictions. Hoping to get it on the dyno soon looking to break 500hp.

Yes, all the time & for several years now, but only under light throttle conditions. It's very safe; WOT or heavy throttle fueling is completely different & is 12.7-12.9:1.