How many of you FI guys run off a SD tune and what are the benefits. Is it more accurate and safer? Is it really much better than just running the maf?

 

I run a 2 bar SD tune. I use it because you can control fuel based on boost levels, so you can run the right a/f. When I had the maf tune, we had to use "tricks" to get the final a/f right, so it would be richer at any level lower than the final boost level.

And, depending on how much power you're looking for, from what I understand you can max out the maf.

 

3 bar SD tune, using hp tuners. Love it so far. It really depends on your expectations and goals as to whether it's better for you. Some guys need it, and others are doing fine without it. Tons of info in the tuning forum though.

 

I ran a maf tune (RPM vs PE) to +700rwhp.....worked great but after converting to 3bar sd EFI Live I'd never go back. So much more control...some additional safety if it overboosts.

 

So what all is required for a SD tune. Search is down. Im assuming a wideband and a tuner of some sort. Any recomendations?

 

i will be paying attention to this too

 

I use HP Tuners, I had to get a 2 bar map sensor, and a wideband. THe only other thing you'll need is do a lot of reading on this forum to study up. But, it's pretty easy really. You just need some time to drive the car and log a lot of data.

 

I would get a pro dyno tune with the SD. Many places will do it for $400+. If you buy HP Tuners, and the sensor, and the etc etc etc, you'll end up spending A LOT more than you originally thought you would.

I own HP Tuners but it was because I did a group sale with 4 other friends that live near me...only cost me $150 so I thought it was worth it.

I'm having TRT dyno tune my MAF...I looking to get around 460 - 475rwhp...

 

they took my car to RPM when TRT didnt tune my car went 472/501 on 7.5psi with stock motor(under drive, LT and ORY) and DUSTIN @ TRT tuned it after the cam and well..... made good numbers, he will always tune my car

 

well I was hoping to have two boost settings, lower daily driver setting and a high track boost level. Wouldnt want any more that 650ish on high setting and maybe 550ish on the lower. I was planning on getting this http://www.moates.net/roadrunner/ to tune with but Ill need to do some more research to see if it will support a SD tune then. If not Im sure I could just use it and swap back and forth between maf tunes.

 

Moates will support SD in real time.

You only need one tune in SD. Tune it for the max boost you'll see and the lower boost will be tuned in.

 

anyone here using a sensor from a Cobat SS?

 

I think the map sensor I have is from the Cobalt. And as someone noted above, in SD you just tune for your higher boost levels, and the lower will be tuned too. The fuel will be right at all boost levels up to the highest boost level you tune for. Definitely the way to go for your plans.

Keep in mind, with an SD tune, it can change as weather changes. That is why I do it myself, and I live in the freakin tropics, I don't even have a real winter. So if your weather changes, it might be worth it to invest in this stuff to do it yourself.

 

so with an sd tune u jsut set it for the highest boost ur car is going to see and it adjust its self but with a maf u have to tune is for every different boost

is that correct??

 

Not exactly. A 2 bar SD tune, you can set up your fuel for all boost levels up to about 14.5 psi. So, if you want 11:1 afr, you can set it up so all boost levels will see 11:1.

With a maf tune, you have to set your fuel up only for the highest boost level you will see. So, if you're running 8 psi, you will have to set the fuel to get that same 11:1, but at 3 or 4 psi, you'll be commanding the same amount of fuel, which would create a rich mixture. This is all due to the sd tune having the capability to tune in a 2 bar setup. The bigger reason we make this switch is to tune in 2 bars, not just to tune sd as opposed to maf. Hope that all makes sense.

 

makes sense, so better tune, better gas mileage and reliability. Sounds like a good reason to go SD to me. So its cheaper to go with HP tuners and get a SD tune than moates? What are the downsides of getting the HP tuner as oposed to the roadrunner?

 

The hptuners lets you tune most necessary parameters in real time, then save changes and update your pcm. Roadrunner lets you modify all available parameters in real time and no need to update the pcm later. It really depends on how many $/feature you feel is acceptable. Also, HPtuners doesn't require a pcm swap, roadrunner does. It would be hard to go wrong with either program.

 

Been reading the responses: Here's as simple as I can put it.

MAF or factory mode (whatever you wish to call it): Uses the MAP sensor to measure pressure in the manifold, the IAT to measure incoming air temp, the flow of air across the MAF sensor, + front O2 readings (if in "closed loop".)

SD (speed density) drops out the MAF and keeps everything else. So, it DOES measure for pressure changes (the MAP sensor), and it DOES measure temp changes (the IAT).

SD is a wiser choice (personal opinion) for FI, as the MAF will be "maxed out" on airflow under boost. Remember that the MAF was designed for a NA car, NOT a FI car. Fuel delivery is thus a "guess" above 105kPA of pressure. With a 2-bar MAP sensor (the Cobalt SS sensor), the MAP and thus the fueling trims can be controlled up to 210kPA. 7PSI of boost would be 1.5x barometric pressure, or 150kPA on the MAP sensor. See where the SD is now allowing to tune for proper fuel under boost vs a MAF, or what's typically called a 1-bar setup, that will stop at 105kPA (zero on the boost/ vacuum gauge...or "no boost".)

Even a MAF tune is usually done by origonally setting the fuel delivery (via the Ve table) in SD mode, then reenabling the MAF and calibrating that for airflow to keep the ideal AF ratio at WOT.

So, 2-bar SD is what I'd recommend. You don't need 3-bar unless you're making OVER 14PSI of boost.

Hope this helps.

 

yea, you explained that much better!!

 

good break down man, makes plenty of sense now. Appreciate the input.