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Tuning

 

Tuning is one of those subjects that is in the eye of the beholder and can be considered to be an extremely simple subject, or an extremely complex one.  It depends upon the experience of the tuner and the depth to which he wishes to pursue the subject as well as what tuning tools he is working with.

Being old school and having spent considerable time at the track playing with various types of cars for far too many years, I prefer to take a broad based approach seeking synergy from the parts.  I am going to try to stick to the basics rather than delving too deep into the theory.  There are so many ways to approach the various systems that I shall hopefully leave you with an understanding and you can fill in the blanks in the way most suitable to you.

Try to learn the difference between theory, empirical results, opinions, and magazine articles or internet claims.   Don't fall for magic numbers or magic parts.

Don't try to compare your car against another car with a different combination running on a different day on a different track with different weather conditions at a different altitude, etc.  It will drive you crazy and mean virtually nothing.  Takes a lot of analysis to normalize cars under such conditions.  If you are that good, you should be betting on horses down at the horse track. 

Don't assume that your car will run tens just because you bought ten second parts.  There are plenty of 12 second cars out there sporting 10 second parts.

First, our cars are 25 years old.  All the original stock parts have many cycles on them. There is no sense blowing a head gasket to prove original fuel injectors can hit the 11's  You will have to go through your car from top to bottom and be sure everything is right before you can expect it to run up to its potential.. 

People often send me PowerLogger files asking for help in tuning their cars.  Far too often, I see problems with the car that are basic in nature.  It is impossible to tune a car to run quickly when it has problems that need to be fixed before the car goes to the track.

Tuning-What can I change to make my car run up to its potential? 

There are really only three things that you can do to alter the tune of the engine assuming you have addressed all the basics.

    1.  Change the fueling. (Match it to the boost-or vice versa)

    2.  Change the timing.

    3.  Change the boost. 

If you want the simplest possible answer,  run as much boost as you can with as much timing as possible with the leanest air fuel ratio possible without incurring detonation.  Note that damaging detonation can occur without you ever hearing it and that is why we must monitor timing retard as the computer has better ears than most of us do.

Before you start changing things, get a spiral notebook, or a logbook made for such things and write down the particulars of each run-temperature, barometric pressure, humidity, wind direction, wind speed, track condition, etc. as well as the performance details.  It's nice to be at a track that gives you info on several waypoints down the track so you can break the run up into segments for analysis.  If tuning for the street, write down the particulars and what you have done...also, put some comments in PowerLogger so that the people trying to help you can understand the differences.

If at the track, make a few runs to dial in your launch technique in order to determine how much boost you can leave at without spinning the tires and how much tire air pressure is optimum.  At the beginning, this may take a few tries until you get it figured out.  Then it should be a lot easier and quicker.

Finally make two or three runs to obtain some baseline numbers to see if you are running consistently as it is impossible to make decisions on fueling and/or timing parameters if the car does not repeat itself under similar conditions.  Remember that changes in air temperature, barometric pressure, humidity, etc. will affect your performance so try to do your tuning when there is not a lot of change going on. 

There should not be any timing retard ...but, if there is, LIFT!  Reduce the boost or add fuel if it appears to be lean, and try again.

Miles per hour is a better indicator of horsepower than is time as time is affected by launch and track conditions more than miles per hour at the line.  At the beginning, concentrate on improving the mph in the lights and then go back and analyze the waypoint information and see if you can tweak the fueling/timing to improve the waypoint numbers-if at the track, of course.

Once you have miles per hour at the finish line optimized and see no other obvious problems such as richness or leanness through out the run, then go back and start trying to find out to improve your short time at the 60' mark.

When it comes to drag racing, it is worth remembering that for each 0.10 second that you can knock off at the 60' mark, you knock approximately 0.15-0.20 off your time to the finish line.  How well your car gets thru the first 60' and how consistently it repeats the performance is make or break when it comes to success.

 

My Own Basic Assumptions when Tuning

1.  I can run less fuel in first and second than I can in third and fourth (don't shift into fourth before the line-hold it in third).

2.  I can run more timing in first and second than I can in third and fourth.

3.  I can run more timing with small turbos than I can with a large turbo.

4.  Race gas is for real race cars.  Alky injection is for anything driven regularly on the street if for no other reason than the cost and difficulty in finding leaded race gas..

5.  Boost makes more power than small changes of timing-particularly on the street on alky.

6.  Due to the lack of change in ambient conditions, I can run closer to the edge consistently at the track than I can on the street so I leave more margin for error on the street.

7.  I can run closer to the edge in the 1/8th mile than I can in the 1/4 mile because the combustion chamber does not have the time to build heat and cause detonation.

8.  Any amount of timing retard resulting from real detonation will do some damage to your engine and will eventually cost you as well as slow you down.

 

Okay, I wrote the following to someone that was asking if I would explain how I would approach tuning his car.  He has a TurboTweak 5.7 chip.  I am not trying to imply that you need a TT chip as opposed to a Bob Bailey chip as I think they both will give exactly the same performance in the hands of someone that can read and understand the instructions and who also understands the goals of tuning.  It's just the mindset that I have when tuning.  Whatever chip you run, read the instructions and understand how the parameters interact..

On your TT chip, you have four parameters that you can adjust.

Parameter 1 controls wide open fueling in all four gears.

Parameter 2 controls wide open fueling in FIRST gear and it is a trim factor based off Parameter 1.  In other words you first set Parameter 1, then you look at your low gear fueling.  If you want to lean it down some to improve turbo spool and get a quicker launch from a standing start, you can.  If you have too much wheel spin from too much turbo spool, you could make it richer and cool down the charge a bit to slow down the spool a bit.  It really depends on how good the traction is and how much boost you are trying to leave on.

Parameter 3 is the timing in first and second.  Normally you can run more timing in first and second at the strip if you can hook the tires because there is less load on the engine and combustion chamber temps are not as high.  This can be a bit more dangerous on the street when the engine is hot because excess timing might cause detonation in that case where it may not on the strip because the engine is cooler.

Parameter 4 is timing for 3rd gear and 4 gear.  Again on the strip you can usually get by with additional timing unless you are hot lapping the car and the engine is not cooled down between runs.

As a rule, I am much more conservative on the street because engine conditions are usually not optimum-particularly if you have been driving in traffic or pounding on the car at boost multiple times.

Okay, so that is what you can do with your chip.  If you had the SD chip you could adjust over 20 different things but there are only a few that I ever touch and seldom at that once I have things where I want them. 

So what about fuel pressure?  It's something that can be adjusted.  When you adjust fuel pressure you adjust every facet of fueling from idle to wide open throttle.  A change in fuel pressure affects flow by taking the square root of the (new fuel pressure divided by the old fuel pressure).  Therefore a change in fuel pressure is a relative small change in the actual delivery but it is more obvious at idle and low rpm than it is at higher rpms because the percentage of change compared to the fueling is larger due to the small amount of fuel used at idle and low rpm.

This is what I do, I set the fueling to 43 (TT chips) and I drive the car until it is fully warmed up and I have done some stop and go driving, then I stop and look at the O2s in gear idling.  If they are 780-800 and the car is idling well, I call it good and forget it.  Note that the O2s will change when you stop and the O2 sensor starts cooling down so your 780 might increase to 810 in a short period of time.  Don't be confused because this is a function of the stock o2 sensor not a change in fueling.

If, when I first stop, the o2s read something like 820, then I reduce the fuel pressure 1-2 psi and try it again, until my first readings upon stopping are in that 780-800 range.  Remember that the TT chips are open loop at idle so that first blm cell is not adjusting the fueling like the factory chip.  It does have some learning capability, however, so that is what I like to drive the car for a bit before beginning to play with the adjustments.  The TT chips are often richer than normal on the default settings.  This is far preferable to being too lean and blowing a head gasket the first run.

If everything is right, the O2s should be pretty stable wherever you set them and they should not be jumping around at idle due to the open loop feature.  That is why the idle is normally smoother and better.

When you come off idle, then the chip goes to closed loop and the o2s will jump around a lot more as the ecm takes charge.

In essence, you can use the fuel pressure to set up your idle and low speed blms but I only look at the idle O2s first when I stop and the sensor is good and hot.

Now, remember that the fuel pressure affects the entire fueling range so the wot fueling will be a little leaner than what Eric put into his default if you reduced fuel pressure at idle with the HOSE OFF so you need to look at the wot fueling to see if it needs adjusting.  Normally, it will probably not be noticeable because the chip was probably a bit rich to begin with for safety's sake.   Be sure to put the hose back on the regulator before you drive it again!

Now, having done this, I go to the wide open throttle setting and start dialing it in.  This needs to be done at the top of third gear so it will approximate what you will see at the finish line.  At this point, I am leaving the timing alone (using the default in the chip) and have the boost set for whatever Eric said the chip was burned for.

If the chip was burned for 25 psi, I would not be surprised to find that the chip was giving plenty of fuel for that boost level and no timing retard was being shown on Powerlogger.  If I am leaving the boost at 25 which is generally a good level for the street when using alky, I start removing a bit of fuel-say no more than two numbers at a time and making a run after each adjustment until I see the slightest hint of timing retard.  I then add about 3% of fuel back to the wot throttle setting and call it good.  I prefer to have some margin of error-particularly on a street car where ambient conditions can vary widely.  This is done with Position 1 in the chip.

If there is a wide band O2 in the car, I typically have numbers between 11.0 to 11.2 in first gear and 10.8-11.0 in third.  This depends upon the size of the turbo, the boost being run, ambient conditions, heads, etc.  I am talking about a mid-ten second to mid-eleven car.

Spraying Methanol at 100%, I would expect my oem O2s to be around 780 on the street.  When at the track, I might lower my fueling a bit and look for something around 750-760 mv but in all cases, I am not going to accept any timing retard on PowerLogger.

Once I am happy with third gear fueling at the top end, I would look at the O2s in first and second from a launch.  Again I want to remove fuel until I am on the verge of timing retard and then add 2-3% back for some margin of safety.  I would guess the O2s will be close to 750 mv but the main thing is NO TIMING RETARD.

If you push first and second too much, you will create a lot of heat in the combustion chamber and this may push third gear over the hill so be careful and don't cause detonation in third by going too far in first and second.  Tuning is a tedious business and there are no short cuts nor magic numbers..  It is all about what works on your car with its combination and the ambient conditions around it on a given day.  That is the reason I like to leave room for a margin of safety.  I like living to fight another day instead of fixing what broke because I was too aggressive.

Okay, I have not mentioned timing.  I think most of Eric's chips have defaults of 23 degs in first and second and 21 in third and fourth.  That seems to work well on the street in most conditions.  At the strip you may get by with adding a couple of degrees more, but, you have to be careful and not make big changes at any one time.  Adding timing in first and second can greatly affect the spool up and the launch.  If you can stick the tires, it can get you out of the hole quicker...or it can make you break traction.   In third gear, I have not seen as much difference and I have seen some awfully quick cars that never used anything but the defaults.  Having seen a couple of cars go 10.4 secs in the quarter with timing set at 18 degs in all gears has biased my thoughts on timing-I admit.  Too much timing can give you regrets a lot faster than too little.  Might note that these cars had the stock factory cam in them as well.

I am not going to mention programming the alky controller other than strongly suggest you start with it set as the manufacturer suggests and read all his notes on tuning the alky flow.  Talk to him about changes.  I don't normally promote vendors over another but, to my knowledge, Alky Control is the only vendor making Buick specific kits and the suggested settings in the instructions will work as well as possible in most cases without additional tweaking for most cars.

I am going to mention valve springs in this section because it is vital to have an engine that pulls strongly to whatever rpm you require to cross the finish line in third.  I used to suggest Comp 980's but they often die after a handful of runs.  When they do, the car will not pull in third gear.  Now, I suggest quality springs that have a seat pressure of 100-125 psi.  Comp 981's seem to be better quality and last longer from various reports.  Note, I am talking about flat tappet cams here, not roller cams.

Finally, accept the fact that the quicker you go, the faster something will break.  The corollary to this is, the faster you go, the more expensive it will be to fix it when it does break.  Stuff happens and none of us are exempt.  It's just that it happens a lot faster to idiots who ignore the warning signals.