What constitues a conservative tune?

[Munch]

A lot of guys list their hp/tq numbers and then add "conservative tune". It seems to me you tune the car to run the best it can but I'm no expert. So what is it that makes the tune conservative?

Also, what kind of power differences would there be between a non conservative and a conservative tune providing there even is such a thing?

[1TZSLO]

My best guess would be as in a daily driver, you get max HP that you can get but its not truly feesible for day to day then turn it back 5-15 for daily gas consumption and stop n go driving. But For me I don't care I drive a Vette. It has to be all or nothing.

[Cobra4B]

People who drag race will tune the cars to the ragged edge as far as engine timing and AFR... the car will make the most power, but it's only being flogged a few seconds at a time. You take that same car and run it around VIR and it may blow up because it's detonating from running lean... especially when the ambient temps get really hot. Also, these cars have issues with the rear two cylinders running lean due to the design on the manifold.... it's more of a straight shot so they get more air. It becomes an issue when people tune for 13:1 at the tailpipe.... most likely those #7 and 8 cylinders are way leaner.... this is what makes many a tuned motor pop running a HPDE..... the detonation breaks the piston.

Another issue w/ a maxed out tune is that the car will be unsafe if you get a bad batch of gas etc. etc.

I want a safe/conservative tune in all my cars... 5-10 horse isn't worth having to worry about destroying it over something stupid.

[pops98]

Brian, Thanks for that answer, did not know about 7 & 8 situation.

[Cobra4B]

Some people will have a 02 bung welded somewhere up close to the engine to get a better AFR. Also, some guys will have their injectors flow-tested and put the two richest one in the rear cylinders.

[Sneaks]

The difference between a "conservative" tune and one that runs the ragged edge usually costs you several thousand dollars in a new motor. Tuning for MAX everything leads to blown up cars all over the place. A certain tuner that travels the COWntry leaves behind a number of these carcasses from what I've read. :leaving:

[Munch]

Cowboom!

[Y2Kvert4me]

Agree with all the above.

It's usually a reference to WOT air/fuel ratio mixture.

With gasoline, the "ideal" mixture is 14.7 parts air to 1 part fuel. This ratio is called stoichiometry, or stoich for short. This value also changes with different fuel types.

In low output "non-WOT" operation (typical of a street car), your PCM is always attempting to keep you at the stoich mixture. This is accomplished from the 02 sensors reading the mixture in the spent exhaust gasses, and telling the PCM to add more or less fuel. That action is what we call fuel trims.


At WOT, with the engine under high load and producing all the output it can. We purposely enrich the a/f mixture, because the combustion conditions run much hotter, and detonation, or pre-ignition can occur, which is what destroys engine parts, usually the tops of the pistons. (yes they will melt!)

By enriching the combustion charge during these high-load conditions, the extra fuel is actually used to help quench or cool the combustion chamber temps, thus helping to prevent detonation.

The question of how much to enrich is what separates an "all-out" tune from the "conservative" tune.

You may find the engine makes it's max hp at 13.2-13.5 a/f mixture on a dyno. You may also find that causes detonation if done often (aka on a road course as Brian alluded to) or in hot weather conditions.
So most tune "conservatively", and shoot for a 12.5-13.0:1 ballpark, which may not produce quite as much power as the leaner mixture, but leaves a bit of safety margin in detonation control.

Cars with FI or N20 usually tune things even richer than that, because those mods will elevate combustion chamber temps much more than a n/a car. Some go so far as to inject water or methanol to further control chamber temps.

It's all about detonation. You want to get near it, but yet you don't want to achieve it. Conservative is safe, and the best choice for most reading this, even if it sacrifices a few hp in the process.


:cheers:

[thegreenman]

Agree with all the above.

It's usually a reference to WOT air/fuel ratio mixture.

With gasoline, the "ideal" mixture is 14.7 parts air to 1 part fuel. This ratio is called stoichiometry, or stoich for short. This value also changes with different fuel types.

In low output "non-WOT" operation (typical of a street car), your PCM is always attempting to keep you at the stoich mixture. This is accomplished from the 02 sensors reading the mixture in the spent exhaust gasses, and telling the PCM to add more or less fuel. That action is what we call fuel trims.


At WOT, with the engine under high load and producing all the output it can. We purposely enrich the a/f mixture, because the combustion conditions run much hotter, and detonation, or pre-ignition can occur, which is what destroys engine parts, usually the tops of the pistons. (yes they will melt!)

By enriching the combustion charge during these high-load conditions, the extra fuel is actually used to help quench or cool the combustion chamber temps, thus helping to prevent detonation.

The question of how much to enrich is what separates an "all-out" tune from the "conservative" tune.

You may find the engine makes it's max hp at 13.2-13.5 a/f mixture on a dyno. You may also find that causes detonation if done often (aka on a road course as Brian alluded to) or in hot weather conditions.
So most tune "conservatively", and shoot for a 12.5-13.0:1 ballpark, which may not produce quite as much power as the leaner mixture, but leaves a bit of safety margin in detonation control.

Cars with FI or N20 usually tune things even richer than that, because those mods will elevate combustion chamber temps much more than a n/a car. Some go so far as to inject water or methanol to further control chamber temps.

It's all about detonation. You want to get near it, but yet you don't want to achieve it. Conservative is safe, and the best choice for most reading this, even if it sacrifices a few hp in the process.


:cheers:


Nice write up. :above:

[WKMCD]

Not ragged edge AFR and timing. I know when Ed tunes my car it usually comes off the dyno 1-2 degrees less timing that the max dyno number. When I travel I don't want to worry about only being able to get 91 octane and not 93.

[Z06PDQ]

good stuff. :yesnod:

[edcmat-l1]

Not much to add that hasn't already been covered. One thing to note is there is a tuning "window" that each motor has. An area where adding or subtracting fuel or timing makes very little difference. When you've reached this window, you know the motor is on it's happy zone, and setting it up with slightly reduced timing, and increased fuel makes it "safe" or SAFER while still maintaining the car's near max power level.

Brian is 100% correct in the difference between a road course tune and a drag race tune. They are 2 TOTALLY different styles of tune. In the road course tunes I run CONSIDERABLY more fuel and LESS timing.

[Benjiusn]

Great Info. Thanks

[Stangkiller]

The difference between a "conservative" tune and one that runs the ragged edge usually costs you several thousand dollars in a new motor. Tuning for MAX everything leads to blown up cars all over the place. A certain tuner that travels the COWntry leaves behind a number of these carcasses from what I've read. :leaving:

:rofl::rofl: