Engine Tuning: Understanding The Basics - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Apex Motorsports · 08-26-2013, 08:33 AM

When I was fourteen years old, my dad bought me my first car. It was a 1970 Chevrolet Chevelle. The first thing I wanted to do was buy the Huey Lewis & the News “Sports” cassette tape for my Hi-Fi stereo, but my pop thought we should start with a little maintenance on the ol’ gal. In those days, a tune meant changing the spark plugs, setting the ignition points and a few cranks on the old Holley four-barrel to get things purring.

In the modern muscle car things are not as simple and engine management is a bit more confusing. The terminology is different, there are all sorts of tables and formulas, there are computer programs, cable attachments and more sensors than most of us care to think about. However, those little tweaks on the carb and changes made with the trusty timing light are the fundamentals of tuning, and they persist in the modern engine. In the end, we’re really just talking about fuel, air and spark. The carburetors provide an amount of fuel to match the amount of air flowing through and mixing those two into the ratio that will give you the power you need when the spark is delivered inside the cylinder.

This is not intended to teach you how to tune your car, but to give you an idea of what is going on with some basic principles of modern engines, how they work and how changes are reflected in the performance.

Internal combustion engines are fairly simple. Take some air, add fuel, throw in a bit of fire and you get an explosion. If you have no clue how the internal combustion engine works, I suggest you take a look at this video which explains a bit about the cycle of a 4-stroke engine. When the narrator mentions the “power stroke”, be aware that this is the time when your engine makes it’s power. All other times during the cycle power is being used.

The mixture of fuel and air combined with the spark creates combustion. The ratio of this mixture of air and fuel changes the power created during that combustion. Why? The air is not always the same concentration. Air is a gas, and subject to the laws of physics. Therefore, when the temperature outside is lower, the volume of air in a given space is more dense. Air density is also different at different elevations. A perfect mix of air and fuel gives you the greatest combustion. The chemistry involved dictates that you need about 14.7 lbs. of air for 1 lb. of fuel. The actual part of the air that we are concerned with is oxygen, because the other components of air are not as relevant to the combustion.

Air/Fuel Ratio

This ratio of air to gasoline is known as the Air/Fuel ratio (AF ratio). An average modern car runs at that 14.7:1 ratio. If you decrease the amount of air (or increase the amount of fuel) to create a ratio in the area of 13.2:1, the car then has a little extra gas to help burn off the oxygen. In general, the more oxygen you can get into the engine and burned, the more power you can make. Hence the reason turbos and superchargers make so many ponies, they are forcing air into the engine, i.e. forced induction. The higher the ratio, the leaner the mix and the hotter the engine temps run. The lower the ratio, the richer the mix and the engine temps run a bit cooler. Think of that 14.68:1 ratio as a gauge with the needle pointing straight up at a point marked “1″. This point is given the name Lambda (λ). If you are running rich you would be at something like .93λ, if you were running lean you might be at 1.03λ.
Now, if this were 1970, we would just adjust these figures with a couple of tweaks with a screwdriver on our trusty four barrel. Today, that is not the case.

Timing

Timing refers to the point in time at which the spark plug will spark. (Here I am referring to spark timing, not valve timing which has to do with the cam) Why does it need to change? Because the air and fuel mixed together do not instantaneously explode. While it is occurring at a very fast rate, there is a little bit of time involved for the burning to take place. Because there is time involved for the mixture to burn, the time at which you want to “start the fire” changes as the speed of the engine changes, because as the engine rotates faster, the speed of burning does not keep pace, therefore the timing needs to change in order for the optimum moment of spark to occur. Your daddy’s old Buick used a vacuum line that adjusted the timing. The modern muscle car uses an electronic method to set timing, and that timing can be changed at more than one point along the RPM curve.

In part II of this tuning series, I’m going to introduce you to some of the sensors that you are likely to find in your late model muscle car, as well as how those sensors are related to the engine management as well as how they are related to each other.

Apex Motorsports · 03-24-2015, 09:13 AM

Bump for Jeremy.

mbowen89 · 03-26-2015, 11:50 AM

I'm curious as to what you are actually changing in the ecm when you are tuning it. Is it just a predefined set of keys and values for that vehicle?

Apex Motorsports · 03-27-2015, 12:25 PM

Quote:

Originally Posted by mbowen89

I'm curious as to what you are actually changing in the ecm when you are tuning it. Is it just a predefined set of keys and values for that vehicle?

Right, this is what it looks like when you are in there.

mbowen89 · 03-27-2015, 06:07 PM

Interesting. What's it look like if you want to disable the rear o2 sensors for example, or change speed limit?

Is this a standardized thing for all vehicles? Or is each vehicle different? Do we initially have to "reverse engineer" the ecm each time a new vehicle comes out?

Apex Motorsports · 03-28-2015, 10:52 AM

Quote:

Originally Posted by mbowen89

Interesting. What's it look like if you want to disable the rear o2 sensors for example, or change speed limit?

Is this a standardized thing for all vehicles? Or is each vehicle different? Do we initially have to "reverse engineer" the ecm each time a new vehicle comes out?

Here is what that looks like.

Different vehicles have different computers controlling them. To tune a car you have to have to correct platform/software to do it. The examples I have shown are for EFILive. EFILive supports many GM gas engines from 06-current. You can tune a Camaro SS with it but not a V6 Camaro. When a new car comes out it does take some time for the aftermarket to "crack" the ECM.

RubyCamaro · 03-30-2015, 12:48 PM

Thanks Chase. Little bit by little bit you are wearing the Newby off me! LOL

Apex Motorsports · 04-01-2015, 05:20 PM

Quote:

Originally Posted by RubyCamaro

Thanks Chase. Little bit by little bit you are wearing the Newby off me! LOL

NYYFan325 · 04-01-2015, 05:35 PM

Let me ask your opinion...

I had a TVS2300 installed and had the tune done through HP tuners at the shop. Would a dyno tune benefit me at all? My installer said it would pretty much be a waste of $$

Apex Motorsports · 04-02-2015, 12:18 PM

Quote:

Originally Posted by NYYFan325

Let me ask your opinion...

I had a TVS2300 installed and had the tune done through HP tuners at the shop. Would a dyno tune benefit me at all? My installer said it would pretty much be a waste of $$

They installed a supercharger and didn't dyno tune it? A waste of money as opposed to what? Did they just load up the canned tune? What shop was this?

NYYFan325 · 04-03-2015, 04:36 PM

The shop doesn't have a dyno, so he did a street tune via HP tuners. So your saying I have some power left on the table?

He loaded the base tune from SLP and made changes from there

Apex Motorsports · 04-06-2015, 06:42 PM

Quote:

Originally Posted by NYYFan325

The shop doesn't have a dyno, so he did a street tune via HP tuners. So your saying I have some power left on the table?

He loaded the base tune from SLP and made changes from there

If he took it out and did a proper street tune it should be in good shape.

Anythingfast954 · 04-07-2015, 08:33 PM

Quote:

Originally Posted by Apex Motorsports

If he took it out and did a proper street tune it should be in good shape.

How hard is it to learn how to tune cars chase?
For my own car atleast?

Kid · 05-15-2015, 08:30 AM

Hey Chase, thanks for the breakdown. I always tuned by AFR, so the Lamda through me off at first.
This may sound stupid, but If I want to run a Lamda of 1.03, why wouldn't you just set that commanded across the board. I have an LLT, HP Tuners w/ LM2, and a CAI. Is timing the factor that wants a richer mixture up top?

08-26-2013, 08:33 AM	#1
Apex Motorsports Drives: 2000 Camaro SS Join Date: Feb 2010 Location: Louisville, Ky. Posts: 25,179	Engine Tuning: Understanding The Basics When I was fourteen years old, my dad bought me my first car. It was a 1970 Chevrolet Chevelle. The first thing I wanted to do was buy the Huey Lewis & the News “Sports” cassette tape for my Hi-Fi stereo, but my pop thought we should start with a little maintenance on the ol’ gal. In those days, a tune meant changing the spark plugs, setting the ignition points and a few cranks on the old Holley four-barrel to get things purring. In the modern muscle car things are not as simple and engine management is a bit more confusing. The terminology is different, there are all sorts of tables and formulas, there are computer programs, cable attachments and more sensors than most of us care to think about. However, those little tweaks on the carb and changes made with the trusty timing light are the fundamentals of tuning, and they persist in the modern engine. In the end, we’re really just talking about fuel, air and spark. The carburetors provide an amount of fuel to match the amount of air flowing through and mixing those two into the ratio that will give you the power you need when the spark is delivered inside the cylinder. This is not intended to teach you how to tune your car, but to give you an idea of what is going on with some basic principles of modern engines, how they work and how changes are reflected in the performance. Internal combustion engines are fairly simple. Take some air, add fuel, throw in a bit of fire and you get an explosion. If you have no clue how the internal combustion engine works, I suggest you take a look at this video which explains a bit about the cycle of a 4-stroke engine. When the narrator mentions the “power stroke”, be aware that this is the time when your engine makes it’s power. All other times during the cycle power is being used. The mixture of fuel and air combined with the spark creates combustion. The ratio of this mixture of air and fuel changes the power created during that combustion. Why? The air is not always the same concentration. Air is a gas, and subject to the laws of physics. Therefore, when the temperature outside is lower, the volume of air in a given space is more dense. Air density is also different at different elevations. A perfect mix of air and fuel gives you the greatest combustion. The chemistry involved dictates that you need about 14.7 lbs. of air for 1 lb. of fuel. The actual part of the air that we are concerned with is oxygen, because the other components of air are not as relevant to the combustion. Air/Fuel Ratio This ratio of air to gasoline is known as the Air/Fuel ratio (AF ratio). An average modern car runs at that 14.7:1 ratio. If you decrease the amount of air (or increase the amount of fuel) to create a ratio in the area of 13.2:1, the car then has a little extra gas to help burn off the oxygen. In general, the more oxygen you can get into the engine and burned, the more power you can make. Hence the reason turbos and superchargers make so many ponies, they are forcing air into the engine, i.e. forced induction. The higher the ratio, the leaner the mix and the hotter the engine temps run. The lower the ratio, the richer the mix and the engine temps run a bit cooler. Think of that 14.68:1 ratio as a gauge with the needle pointing straight up at a point marked “1″. This point is given the name Lambda (λ). If you are running rich you would be at something like .93λ, if you were running lean you might be at 1.03λ. Now, if this were 1970, we would just adjust these figures with a couple of tweaks with a screwdriver on our trusty four barrel. Today, that is not the case. Timing Timing refers to the point in time at which the spark plug will spark. (Here I am referring to spark timing, not valve timing which has to do with the cam) Why does it need to change? Because the air and fuel mixed together do not instantaneously explode. While it is occurring at a very fast rate, there is a little bit of time involved for the burning to take place. Because there is time involved for the mixture to burn, the time at which you want to “start the fire” changes as the speed of the engine changes, because as the engine rotates faster, the speed of burning does not keep pace, therefore the timing needs to change in order for the optimum moment of spark to occur. Your daddy’s old Buick used a vacuum line that adjusted the timing. The modern muscle car uses an electronic method to set timing, and that timing can be changed at more than one point along the RPM curve. In part II of this tuning series, I’m going to introduce you to some of the sensors that you are likely to find in your late model muscle car, as well as how those sensors are related to the engine management as well as how they are related to each other. Last edited by Apex Motorsports; 12-28-2015 at 04:57 PM.

03-30-2015, 12:48 PM	#7
RubyCamaro Jan Drives: 2010 Camaro 1LT Red Jewel tintcoat Join Date: May 2010 Location: Springfield, TN Posts: 16,225 View My Garage	Thanks Chase. Little bit by little bit you are wearing the Newby off me! LOL __________________

04-01-2015, 05:35 PM	#9
NYYFan325 Drives: 2010 Camaro 2SS/RS Join Date: Mar 2012 Location: Las Vegas, NV Posts: 508	Let me ask your opinion... I had a TVS2300 installed and had the tune done through HP tuners at the shop. Would a dyno tune benefit me at all? My installer said it would pretty much be a waste of $$ __________________

04-03-2015, 04:36 PM	#11
NYYFan325 Drives: 2010 Camaro 2SS/RS Join Date: Mar 2012 Location: Las Vegas, NV Posts: 508	The shop doesn't have a dyno, so he did a street tune via HP tuners. So your saying I have some power left on the table? He loaded the base tune from SLP and made changes from there __________________

05-15-2015, 08:30 AM	#14
Kid Drives: 2011 Camaro 2LT, 68 Camaro RS Join Date: May 2010 Location: Milford, CT Posts: 627 View My Garage	Hey Chase, thanks for the breakdown. I always tuned by AFR, so the Lamda through me off at first. This may sound stupid, but If I want to run a Lamda of 1.03, why wouldn't you just set that commanded across the board. I have an LLT, HP Tuners w/ LM2, and a CAI. Is timing the factor that wants a richer mixture up top? __________________ 2011 Black/Inferno 2LT. Inferno Brembos, MRT 2.0, Vararam, BBK LTs, RX Catch Can, VMAX ICE-olator, VMAX P/P Throttle Body, Monster clutch, MGW Shifter, OverKill Tuned.

03-24-2015, 09:13 AM	#2
Apex Motorsports Drives: 2000 Camaro SS Join Date: Feb 2010 Location: Louisville, Ky. Posts: 25,179	Bump for Jeremy.

03-26-2015, 11:50 AM	#3
mbowen89 Drives: 2015 CRT 2SS/RS 1LE Join Date: Feb 2014 Location: IN Posts: 638	I'm curious as to what you are actually changing in the ecm when you are tuning it. Is it just a predefined set of keys and values for that vehicle?

03-27-2015, 06:07 PM	#5
mbowen89 Drives: 2015 CRT 2SS/RS 1LE Join Date: Feb 2014 Location: IN Posts: 638	Interesting. What's it look like if you want to disable the rear o2 sensors for example, or change speed limit? Is this a standardized thing for all vehicles? Or is each vehicle different? Do we initially have to "reverse engineer" the ecm each time a new vehicle comes out?