We just finished a very mild 441 motor. The tuning was very interesting
At WOT and high RPM we noticed that the MAP Kpa never got to 100. That means there is still vacuum caused by retriction in the intake tract.
We tuned it as best we could with the MAF in place then removed the MAF and tuned it in speed density. Timing was not touched. Only the fueling through the VE tables was changed. It's not any richer or leaner, as you can see.
You can see by the graph that removing the restriction (the MAF) we picked up considerable power. Just food for thought.
This is not to mention the fact that in speed density, we can get wild cams to idle smoothly and be totally driveable.
I don't have a MAF on my car and it idles like stock. ( Well it did before I pulled the motor out anyway )
We can now tune both the C5 and C6 in speed density.


I also inclued a picture of the early MAF, late MAF and the air filter without the MAF. You can clearly see that more air can flow through with the MAF gone. Also air turbulence through the MAF is no longer a factor.

 

Very nice, And you better bet the bigger the cam/engine the bigger the gain.
Phil

 

All most 20 hp gains and now more streetable, that is great progress for those wanting a wild cam. No for is with FI will we be able to use a more aggressive cam and what will this do for our gains

 

SWEET - keep up the good work guys! Now that's some whiplash torque

 

Andy,
so now that it is tuned in SD mode are you going to return to running with MAF (non-sd) for better accounting for weather / pressure / temp variances?...or keep it in SD mode, in which case what might the draw backs be?

 

Removing the MAF does not allow more airflow for the diameter of TB and intake runners are still the same and in any case the cylinder volume only takes a few grms per second along with the intake mainifold is called a "reserve" by GM for good reasons.

By removing the MAF you have forced the PCM not to be able to properly compute torque and could force drive by wire to turn off torque management altogether and cause car to crash as been reported many times by owners who claimed TC never kicked in.

All nameplates if its GM and the C5R. C6R, 06 ZO6, Viper you name it put out high performance and still use a stock MAF.

There is no reason with proper tuning that the MAF can do what EPA and GM designed and a little basics :
the PCM ONLY obtains BARO from the MAP sensor at startup and then at WOT and puts it into KAM so when running only SD you do not even have BARO realtime changes with the limits of VE.

Show us in most engine setups including radical cams used where the MAF even comes close to its maximum air mass, in fact show us where our engines even eat more then 640 CFM of air which is no where near even a 80 mm MAF which can flow 850 CFM of air.

It seems to me tuning vendors doing marketing by claiming the SD tune when they cannot even prove cases where a N/A engine could even use more air when the PCM timing tables only understand 1.2 grms/cyl at the most.

As to your not getting to 100 KPA MAP, learn the basics, the car has to be at sealevel, the higher above that the less max KPA there can be and the corrected weather values are needed which cannot be done with out the device that does that - MAF

 

 

..

you've obviously not been around here long enough ..

 

boosted_z06 - re your post...
First, let me say that I am not an expert on this subject, and not in a position to dispute your (or anyone else's) claims regarding SD tuning. However, I do know a little bit about human behavior, and your provacative and insulting tone are not likely to elicit a useful exchange of ideas (which is kind of the point of posting to a technical forum in the first place).

1. GM and the EPA may know best, but clearly there is some value to speed density. A cottage industry has sprung up around this technique, especially in Australia. Are all these people wrong? I would also point out that 90-91 Corvettes came from the factory MAF-less, with SD tuning. Did GM abandon this because it was a bad idea, or because they couldn't perfect it? I don't know.

2. As to your suggestion that the Andy " learn the basics, the car has to be at sealevel" ... learn to read a map - Andy's shop is at sea level. How do like the taste of your own medicine?

3. We know about his qualifications. Let's hear about yours.


P.S. I am not a minion of the A&A fan club, but vendor bashing seems to have become a popular sport here lately. Why don't you back up your claims with a few facts?

 

Glad to hear that some newer tuning software and the addition of speed density tuning are getting bigger cam cars smoother and more driveable at lower rpms.

 

Where is boosted z06 Vendor bashing? He's just stating a difference of opinion. What he said is factual. SD tuning is old science and the Industry has moved on.

If you don't agree, that's fine, but why flame him personally? Sounds like Bush attacking the Democrats.

 

My car has the IAT sensor built into the MAF. If I would want to complety remove the MAF can I just purchase a IAT from earlier year C5's that did not have the IAT built into the MAF. You could then splice into the wires running to the maf and wire in a standalone IAT. Would this work? Anyone know what wires to splice into?

 

 

This car is getting the MAF reinstalled. It was just to show people who wonder about the differences.
As for no restriction? There certainly is some restriction. KPA was 104 with the MAF out.
We only do speed density tuning for off road vehicles. We've found better throttle response and better power on race cars. That's all.
I'm certainly not suggesting everyone should switch to SD.

 

Yes, you can use a regular two wire IAT sensor if you wish to stay in SD. IT works well.

Rick

 

Dont worry about SD tuning Andy. It seems in all my other posts as well that we are wrong for letting some guys go that route too.

 

how much more is it for a sd tune than a regular tune? can this be done safely with my car being driven 3 times a week? thanks..

 

Seems like some instances of opinion masquerading as fact here!
Some facts:
o -GM and others currently use the SD portion of the system for fast response and MAF for steady state accuracy, driven by emissions concerns more than performance.
o ~1990, GM issued a service calibration applicable to 3 or more model years, millions of V-6 Cavaliers, etc., to correct driveability problems. Unmentioned except to the EPA was the fact that it completely disabled the MAF in favour of pure SD calibration...
o -MAP calibration occurs at key-up, and every time WOT is used at low RPM. How many times per year do most of us climb or descend say 6,000 ft. without ever encountering those conditions?
o -If removing a MAF with integral IAT, it is as stated a simple job to fit a stand alone sensor.
o -Flow losses are cumulative. If you plumb in series an aircleaner, MAF and TB each of which "flows 'X' CFM", the system as a whole will flow way less than 'X'.
o -Most intake flow tests are done at 1.5" Hg. pressure drop. This value was chosen in the fifties for the then-new 4 bbl. carbs, as much to avoid the need to upgrade the OEM's flow bench motors of the era (which were designed to handle 2 bbls. @ 3" Hg.) as to match the then-typical intake pressure drop of an engine at high RPM WOT. It has no direct relationship to what a current EFI engine, with no dependency on vacuum-assisted fuel atomization, "needs".
o -An engine with a typically calculated "CFM requirement", [(displacement x RPM)/2] x V.E., will therefore, when fitted with a complete intake system rated at this same CFM, operate at peak RPM WOT with a pressure drop of 1.5"Hg./5.1 KPa This represents a restriction and hence power loss from an unrestricted state of 1.5/29.92 (5.1/101.325) or ~ 5%, a 25 HP loss on a 500 HP engine.

OK, I'm buckling up my flak jacket now...

 

Rookie,
that means we are listening to what they have to say

dumb a$$

 

This should be the quote of the Month. I like honesty.

Thanks Andy.