Well, I dropped off my 07 Z51 MN6 today at Synergy Motorsports for a few mods. The car currently only has A Callaway Honker CAI. They will get some baseline dyno numbers before the following is installed:

LG PRO catted headers and X pipe (Jet-Hot coated)
B&B Bullet exhaust
Lingenfelter 160 degree thermostat
NGK TR55IX plugs
MSD plug wires
Tune

Which tune would benefit me more and why? Is speed density tune only more advantageous when you have a turbo / supercharger/nitrous?

I need to know ASAP, please

 

Are all the experts asleep?? ZIG, HITMAN, CYA, etc...??

 

I am no expert, but I think SD tune is used primarily to tune FI setups since the MAP doesn't work with boost. SD tunes are also used to smooth out a hotter cam. Since you have neither of these, you should not need it. That said, the real expert here is working on your car right now. Just ask Rick what he thinks is best and most cost-effective. And ask him why he did what he did so you know next time.

 

Sure, the car has not been tuned yet, that is why I am asking. I am trying to understand the difference of one tuning technique over the other, and which one wold benefit me the most. I always see posts here about people raving about speed density tunes.

 

What I am hearing from Spin, Hitman and various tuners, is that the big thing on the C6 is to sharpen up the sluggish factory tune, which results in lethargic engine response. This consists of thinning out the AF trims and removing TM. Also, the ECM reacts to increased flow from mods (or seemingly to any xhange) by pulling timing. That is why a "regular" tune is essential on these cars. The outcome should be that the engine feels much cripser and a good bit stronger.

HPTuners seems to be the vehicle of choice. I really don't think SD would offer much over a standard tune because you are not exceeding the parameters of the stock MAF and MAP (i.e. boost or Nos), and you are not trying to smooth out a choppy cam.

Hopefully others with more knowledge will step in here and get you specific answers.

 

Thanks TT, any others??

 

Brasil, I haven't offered an opinion on SD tuning because I have no personal experience with it. I've read some stuff, but that's it.

I do know at least one local racer who was once a big proponent of SD tuning, ran at the track most of this year without a MAF, but has now put his MAF back on. He is currently experimenting with the new EFI Live handheld programmer, have some success.

 

Thanks HIT. I always trust your opinion on other subjects that you are well acquainted with, and will inquire your opinion when I am ready to get a CAM

 

You might also wish to talk to Phil97SVT, he does a lot of speed density tuning for F-bodies. Also Keith at HP Tuners can provide info on which tuners around the country are using the HP Tuners software to do speed density tuning.

 

Speed density tuning or more properly, VE tuning, tunes the car's volumetric efficiency table with the MAF turned off. The MAF is then turned back on and tuned in the same way it would be in a MAF or closed loop tune. The pcm makes predictions about fueling and checks those predictions against the actual measured airflow from the manifold absolute presure sensor and the MAF (airflow). The car inevitably runs smoother when the VE tuning is done and dials in the VE table correctly to such a degree that with the MAF disconnected, the car runs better than it ever did in closed loop.

After the speed density tuning is completed the car does run in closed loop with the MAF in the system. This is the best way for fuel economy. You may choose to run the car in speed density altogether in which you may delete the MAF and connect the intake air temperature sensor in the intake ducts. The benfit of this is that the restrictive MAF isnt in the air tract.

I was amazed upon completing my first speed density tune with a 228/232 cam which is near indistinguishable from stock drivability. Even with no MAF in the system and running speed density during the tuning session, I was amazed at the smoother running engine, ability to drive in a parking lot at 7 mph and the lack of bucking, surging and running abnormalities. When your head/cam car can run at 1100 rpm in sixth gear and accelerate smoothly up to the upper rpm ranges you know you have a good tune. Aintqik and I were able to get his 403 stroker to do exactly the same with a half completed tune.

Without tuning the car in speed density, it is usually only optimized at WOT and will never have the silky revs of a SD tune.

It shouldnt be a consideration at this point as to getting this type of tune or not. The speed density tune is a more complete tune and if someone chages you 500 bucks for a 30 minute WOT tune, you got ripped off.

The cars I have tuned for free for locals have been tuned in speed density. I was taught how by Phil97svt. He is a great tuner.

Corvettes of westchester also tunes the VE table. Your car spends most of its life in closed loop and drivability should be tuned in. Dont be concerned sley with peak HP. A car that is properly tuned will have much more low end grunt.

 

In my opinion....ALL CARS should run with a MAF...I think SD tuning is a shortcut....You will have much better results if you tune it right with a MAF.

I would only us SD if a vehicle was "soooo radical" that it ran too inconsistant for street use.....or maybe a vehicle that was only used at the track.....

REMEMBER: SPEED DENSITY is a FAILSAFE function of the pcm designed ONLY to help the car get to saftey in the event of a major system failure. Early tuning techniques used SD tuning because software was not perfected and tuners didn't know very much about how the system worked.....

Again, in my opinion.....Save SD for the track......

Hope this helps,
Chuck CoW

 

 

that's funny.

 

100%

i'll need to reread it once i wake-up, but a quick read has me in agreement.

basically, if you are able to tune the car so it runs the best it can without the use of the 'real-time' tuning aids (feedback from the various sensors), provided the 'new' airflow, fuel, etc. are not outside the 'bounds' of the sensors, once the sensors are added back into the system they will perform like a 'fine-tuning' ****.

 

100% disagree with saying speed density tuning is a shortcut. I know you worded that wrong and meant running in speed density all the time is bad. There is no other way of tuning the VE table for cars that have one. I want to see a 228+ cammed car that is tuned without speed density tuning. Tuning stock cammed cars is a joke since the VE is done already.

I agree that the MAF was needed in the system and never said to RUN in speed density after the tune. I specified that it gets reconnected.

You have to do a full re-tune when the MAF is put back into the sytem. The stock VE table is 100% wrong for anything other than the stock cam. You cant tune VE without running the car in speed density during the tunewhich is why it is called speed denstiy tuning. Anything else is a guess. No way a cam greater than 230 intake duration will run without drivability issues without touching the VE table. If it does then the tuner just altered the VE table near idle and low RPM loads to get it better...but it isnt optimum. The car should run fine if the MAF fails. If you disconnect the MAF and the car runs poorly, you have a bad tune. If you disconnect mine, it will run nearly the same. I would be interested in seeing a cammed car that you tuned if you didnt touch the VE table. I am willing to bet the car wouldnt run so great if it was disconnected. I was under the impression you did tuning in speed denstity mode to avoid the closed loop pitfalls.

I agree about running SD at the track but I must clarify that I was talking about tuning a car in speed density as it has to be since the MAF skews the fueling, not running the car after the fact in speed density. The VE table has to be tuned in speed denstiy to avoid the MAF's adjustments. Tuning the VE table while in closed loop is a guess and not perfect. The VE table has to be fully tuned cell for cell. You need a wideband and must log A/F without the MAF in the loop. PE gets set to a commanded 1.13 and the VE table is dialed in cell by cell and you cut and paste the error percent that you log on a wideband directly to the VE table. The MAF then gets put back in the system and you re-tune for non-positve LTFT's....and yes, the injector flow rate remains untouched

Tuning a car in speed density mode doesnt mean running speed density. Once again, I stated you turn the MAF back on. It is still a speed density tune.

As far as the benefits, the MAF restriction has shown a 20hp gain once deleted. (A&A corvettes)

 

I think the difference is .......running without a MAF is speed density....I think that tuning a car without a MAF when you intend to RUN without a MAF is speed density....

I think that tuning a car "in speed density" When your intention to run a MAF is something different.

In the world of EFI LIVE...It's called "AUTO VE TUNING". where you run without a MAF to help make the VE perfect..then turn the MAF on when you are ready to finish tuning.

Everybody calls it something different....It depends on what you call it....

EVERYONE will agree that SD is a "failasfe" of the GM PCM and tuners took advantage of that failsafe to create "running in SD mode".

Again, if your setup/combination dictates tuning without a maf to run without a maf....then it is SD......

If you tune with SD to perfect your VE table then turn the MAF on with the intention of RUNNING with the MAF....I would not call it speed density tuning......

Chuck CoW

 

I think we are saying the same thing differently. Chuck, do you start VE tuning then do MAF?

If your car is modded, you want to start with the computers "predictions" of air at given rpms so the VE table predictions and what the MAF sees are closer. An unmodded car could use a stock VE table because the computer's "predictions" (VE) table is pretty much dead on.

This is more of a question than a statement lol!

 

Yes, that's how I do it.....


Chuck CoW

 

You're just agreeing now because its my turn to pay for lunch next time.

All cleared up.

and RJ, stop making like you know about cars.

 

I almost forgot;I did specify that it should be called VE tuning as per my original post in this thread. Gimme some credit.