MAF vs Speed Density

**00blacktransam112** · 02-11-2010, 09:27 AM

so for converting, could i just send the PCM for a mail order or would it have to be a dyno tune session. and do you just take the MAF out and tape the connector up and not use it? do you need to buy any parts for the conversion?

**Smittro** · 02-11-2010, 11:09 AM

For my TT project I'm using a stand alone with an on board 3-bar MAP. SD FTW. My (z34) did'nt come with a MAF stock so no need to add one.. I'm using the old ecm to control the dash and the tranny shift points. I'm not a drag racer so for me different shift points it's only a matter of changing a chip in the stock ECM, everything else, fuel, spark, boost, etc. etc. will be handled by the stand alone.. So IMHO, MAF for N/A and SD for boost.

**Smittro** · 02-11-2010, 11:12 AM

Originally Posted by 00blacktransam112

so for converting, could i just send the PCM for a mail order or would it have to be a dyno tune session. and do you just take the MAF out and tape the connector up and not use it? do you need to buy any parts for the conversion?

Frost will prolly be along for that one. But I'm not sure you can just change a MAF reading ecm to an SD. But Frost knows better than I..

**0rion** · 02-11-2010, 11:17 AM

you basically just fail the maf in the tune and unplug it physically, you can then remove it altogether from the car if you want to. There are ve tables already in the pcm so then you can log with a wideband and make changes to the ve to dial them in. Frost tunes a lot of these cars so maybe he knows something I don't but IMO the car should be in front of someone to do a ve tune. Could probably do it on the dyno but to me it would make much more sense to hit all the cruise cells on the street and save the WOT stuff for the dyno.

**00blacktransam112** · 02-11-2010, 12:53 PM

thats what i figured orion. i guess im savin my pennies up for a real tune then

**sjsingle1** · 02-24-2010, 07:46 PM

I always wonder if my bird could be converted to SD, very interesting...........we need some more testimonials here

**BDowning** · 02-25-2010, 06:10 AM

I run a SD tune on a cam car and would not change a thing. It does take longer to set up all the tables but it's worth it!!!

Bill

**0rion** · 02-25-2010, 06:12 AM

Originally Posted by sjsingle1

I always wonder if my bird could be converted to SD, very interesting...........we need some more testimonials here

any of the f-bodies can be tuned to run in SD. Do you need it? IMO the maf does fine for stock and bolt on cars and even some cammed cars. I personally wouldn't mess with it unless you're cammed or having issues with the maf. That's just my opinion.

**KP1** · 02-25-2010, 07:44 AM

When you eliminate the MAF and run Speed Density, your fueling is determined based off the Volumetric Efficiency tables. If you keep the MAF, below 4K rpms, your fueling is MAF based with VE table blending. The MAF is trying to determine air flow and base fueling on TP, IAC, MAP, blah, blah, blah. If you want to read all about it, go to the HP Tuners forum and the EFILive Forum. There's enough there to keep you busy for the next year or so.

Frost has been at this for a good while now and he knows what he's doing and is 100% right that there are alleged tuners out there who'll take your money and do very little for you. As for dyno tuning, that usually means wide open throttle tuning. I was unimpressed with the dyno tune I got before I started dabbling in it myself. It takes a lot of time to run a car through all of the throttle/RPM/load circumstances and dial it all in. Some guys have done so many of these cars that based on your mods, they can get it as close as you'll ever need it without getting near a dyno. Some others will get in there and mess with parameters they have no need to touch and they'll balme all of your issues on the cam or something else. There are some witch doctors making money selling tunes.

If you can, hook a wideband 02 sensor up to a stock LS car and observe. If you think it'll always be reading stoic because GM has it right on the money, your in for a little surprise.

Anyhow, I've been Speed Density for 4 years now tuning with EFILive and without a doubt, throttle response in speed density is the most notable fun factor to be gained.

**sjsingle1** · 02-26-2010, 08:59 AM

so rip out the MAF and a good tune is all you need for SD?? but do you have to do the tune yourself? I think that HP tune software is not cheap....and then the learning curve for it....oh boy

**KP1** · 02-26-2010, 09:08 AM

You do not have to remove the MAF. You can send your PCM to Frost or Wait4me or other mail order tuners, with your engine and drivetrain specifics and they can do an SD tune and send the PCM back to you. Or you can buy HPT or EFILive and start learning/tuning yourself.

**Hi-Po** · 02-26-2010, 09:50 AM

I wouldn't want a mail order SD tune. Ive done email tuning with Frost (I own a wideband and HPT Pro) and we did SD. If you have any sort of mod's done to the car, I cant see just one crack at it nailing down a SD tune. Frost will be able to say for sure on the SD mail order.

If your basic Mod's (Lid, LS6 intake, PP TB, headers) I wouldn't worry about doing a SD tune just yet. Unless you get a real dyno tune, in person, or email tuning like what I did.

**sjsingle1** · 02-26-2010, 11:33 PM

I just checked out the EFI live site.......lots of stuff there..........where to start?

**00blacktransam112** · 02-27-2010, 08:35 AM

im not even gonna bother doing it myself

**408WS6** · 03-03-2010, 06:46 PM

There is another advantage to running an SD tune: if you bracket race, your times will be more consistent which is what you want. I got tired of losing because I couldn't run within .06 of my dial in time. I noticed some of the more experienced LS1 bracket racers were running SD tunes. When I went SD, the first time I went to the track I ran right ON my dial in time, and can usually get within +/- .010 or even closer on a regular basis. If you go with an OLSD, I'd recommend running a wideband, and do some logging for awhile until you feel comfortable with the tune.

**Ryans99LS1** · 03-14-2010, 06:37 PM

Been thinking of going SD when mine gets tuned. Im just curious when the MAP sensor comes into play? everyone says to switch to SD you just tune for it.. but then there is talk about MAP sensors, so when is that needed?

**0rion** · 03-14-2010, 07:01 PM

Originally Posted by Ryans99LS1

Been thinking of going SD when mine gets tuned. Im just curious when the MAP sensor comes into play? everyone says to switch to SD you just tune for it.. but then there is talk about MAP sensors, so when is that needed?

you already have a map sensor......what you may be talking about is for boosted cars. They'll go to a 2 bar or above map sensor.

**Frost** · 03-14-2010, 08:15 PM

SD tuning through the mail is, contrary to popular belief, not only possible, but in many cases easier to get right than with a MAF. Every MAF is a little different and reports a little differently. This is the single hardest part of mail order tuning.

I just wish all of the internet SD myths would end. Every week I get an email from a customer explaining that he doesn't want SD because it doesn't adjust to XYZ condition...

**Hi-Po** · 03-14-2010, 08:28 PM

Originally Posted by Frost

SD tuning through the mail is, contrary to popular belief, not only possible, but in many cases easier to get right than with a MAF. Every MAF is a little different and reports a little differently. This is the single hardest part of mail order tuning.

I just wish all of the internet SD myths would end. Every week I get an email from a customer explaining that he doesn't want SD because it doesn't adjust to XYZ condition...

I dont hear it that often, and Ill be the first to admit I said something along those lines a few weeks ago. It just seemed like it would require more then one flash to get it right, like when we worked on my SD tune for example.

Thats all I was getting at, but your point on MAF's seems very valid and I understand it.

**Frost** · 03-14-2010, 10:03 PM

Originally Posted by Hi-Po

I dont hear it that often, and Ill be the first to admit I said something along those lines a few weeks ago. It just seemed like it would require more then one flash to get it right, like when we worked on my SD tune for example.

Thats all I was getting at, but your point on MAF's seems very valid and I understand it.

It all depends on the info that I have at hand when the tune is made. Even now, all calibrations are still evolving. For example, the base I'd made for your car would be much different getting started if I made it now than it would have been a year or so ago. For boltons cars (and many many others), I have many examples to draw from and use as a base.