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1Greyteg · 02-20-2003, 11:46 PM

First,

You must only do this on a Dyno. And you MUST remember that ALL cars are different and act and react differently to tuning.

And it helps if you can tune with a wideband O2 sensor.

It also helps if you have an adjusatable fuel pressure regualtor.

I will post a clear and deep descrption and up front will credit my Friend TUAN. Not that I couldn't tell you, I can, but, I might miss something and his article is just very well written:

From TUAN at TI:

"1. Find the Best VTEC Switchover Point First (if you have VTEC):

Set the VTEC controller such that the VTEC switch is at 7000 rpm. The dyno pull will be done almost entirely on the non-VTEC lobes.

Locate the highest rpm at which the hp dies on the non-VTEC lobe. Go 200 rpm before this point and that is YOUR best VTEC switchover point.

Look at this run's graph and determine where you want the power gain to be...in the upper rpms or in the midrange. The true power gains from tuning come in the next step.

2. Tune the Wide Open Throttle Fuel Map:

From your baseline dyno pull (after step 1 for the VTEC people), identify on the torque vs rpm curve the areas where torque has dropped or dipped. These are your target rpms to plug into the fuel controller's fuel map(s).

The airel ratio vs rpm plot for the most recent baseline dyno pull will tell you whether you need to richen up or lean out at each of these target rpms where the torque has decreased.

The goal is to have a flat horizontal torque curve sitting at peak torque for as long as possible without reducing your injector duty cycle too far, especially when VTEC has engaged.

The goal is not a specific airel ratio. The airel ratio is the means to an end not the goal itself. It is only a compass that tells you the direction of fuel delivery to tune or dial in (i.e. richen more or lean out more at the target rpms). The torque will tell you whether to continue or stop. Get rid of the torque dips. However, I would not proceed past higher (leaner) than an airel ratio of 13.5:1 or if you already hear knocking. A caveat: You usually cannot hear knocking at high rpms anyway so don't base your decision on your ears. Some tuners have pushed to 14.0-14.5:1 in some all motor Hondas...I am a chicken.

The way some fuel controllers work is by altering the manifold absolute pressure (MAP) signal to the ECU. The MAP is an indicator of air flow. To get the ECU to open the fuel injectors longer, the fuel controller changes the true incoming MAP signal to the ECU into a larger voltage. The ECU is tricked into thinking there's more air and adds the correct amount of fuel. Some fuel controllers max out at 12-14% increase, since >14% gain on the manifold absolute pressure voltage signal by the controller trips a check engine light because the ECU thinks you are running boost. If you have maxed out on the increase in fuel from the controller and may need a little more at the upper rpms, you can increase fuel pressure slightly to see if this gives you more fuel increase but unfortunately this increase will be across the entire rpm range. If you do need to up the fuel pressure regulator setting then, remember to adjust in the rpm areas where you need to lean down further afterwards. There is set limit on the fuel controllers as to how far you want to lean down. I've never used an exhaust gas temperature reading to tune my WOT fuel curves but some FI people combine it with the wideband readings for their tuning. You need to have the EGT probe placed 2 in. max. away from the exhaust manifold flange to get an accurate reading. This involves drilling a hole in a header primary near the flange: something most people won't want to do.

3. Cam Gear Tune:

The 2 most dangerous situations are if you retard the intake or exhaust cam gear too much because these are cases when you decrease piston to valve clearance and risk piston to valve contact. Most people say do not push past 6-8 degrees unless you have measured clearances and know that it is safe to proceed past this point. Having said this though many of the top power makers I know have gone to 10 degrees or more (knowing and measuring ahead of time that it was safe to do so).

a) If you want more midrange gains than upper rpm gains: Widen the lobe separation angle (reduce the overlap). Simultaneously retard the intake cam gear and advance the exhaust cam gear in 2 degrees increments for each setting (2 dyno pulls) until you no longer get any more gains. I would not go past 6-8 degrees retard unless you have measured piston to valve clearance (clay tested) and know for sure it is safe to go past these points.

b) If you want more upper rpm power than midrange: Tighten the LSA (increase the overlap). Advance the intake cam gear in 2 degree increments until you no longer get any upper rpm gains. Now retard the exhaust cam gear in 2 degree increments. You have to be careful here because too much exhaust cam gear retard can lead to piston to exhaust valve contact. I would stop at 6 degrees advance, if you are unsure of your sclearances. Again you are doing at least 2 successive pulls for each setting and then stopping to allow the engine to cool down a bit.

You want to find the best overlap for the highest gain in the rpm area you want. Stop when you see no further gains.

4. Tune the Ignition Timing After Each Intake Cam Gear Adjustment.

The intake cam is directly connected to the distributor and affects spark timing. If you have changed the intake cam gear, you need to bring the spark timing back to your desired setting.

Do not advance spark timing too far. It really depends on whether you have a J&S Safeguard to protect against detonation, the fuel octane rating available, and your compression ratio. Advancing ignition spark timing increases peak cylinder pressures and therefore, increases temperatures and runs a higher risk of detonation.

If you have greater than 11.4:1 static CR without knowing the airel ratio across your entire rpms, I suggest that you do not exceed 16 degrees BTDC.

For most of you with 9.2-10.9:1 static CR, IMHO there is no gain to going past the maximum factory spec of 18 degrees BTDC. Some do benefit at 19 degrees BTDC. Remember that advancing not only increases the risk of detonation but also increases the wear of engine parts from high spikes in peak cylinder pressures and temperatures. I would rather have my engine last longer than gain 3 extra whp from pushing advance on the spark timing. I have run as high as 21 degrees BTDC at 10.8:1 CR but I had bigger 270 cc/min injectors at the time and ran very very rich. I've always eventually turned the spark timing back down to 18 degrees BTDC for safety and longevity reasons.

5. Reality check

Some people reset everything back to their original settings at the start of the session and do 2 pulls at the end of the session just to make sure the new settings improvements weren't due to heat sinking of the engine or things other than the settings themselves.It's a good quality control check for you to believe in your final dyno readings.

cheers"

Many thanks to my buddy Tuan, he deserves it!

Hope I helped ya,

A.

02-20-2003, 11:46 PM	#2 (permalink)
1Greyteg S Zero Racer Join Date: Feb 2002 Location: Phut, the Shuk Up! Posts: 2,812 Car: Mods:	First, You must only do this on a Dyno. And you MUST remember that ALL cars are different and act and react differently to tuning. And it helps if you can tune with a wideband O2 sensor. It also helps if you have an adjusatable fuel pressure regualtor. I will post a clear and deep descrption and up front will credit my Friend TUAN. Not that I couldn't tell you, I can, but, I might miss something and his article is just very well written: From TUAN at TI: "1. Find the Best VTEC Switchover Point First (if you have VTEC): Set the VTEC controller such that the VTEC switch is at 7000 rpm. The dyno pull will be done almost entirely on the non-VTEC lobes. Locate the highest rpm at which the hp dies on the non-VTEC lobe. Go 200 rpm before this point and that is YOUR best VTEC switchover point. Look at this run's graph and determine where you want the power gain to be...in the upper rpms or in the midrange. The true power gains from tuning come in the next step. 2. Tune the Wide Open Throttle Fuel Map: From your baseline dyno pull (after step 1 for the VTEC people), identify on the torque vs rpm curve the areas where torque has dropped or dipped. These are your target rpms to plug into the fuel controller's fuel map(s). The airel ratio vs rpm plot for the most recent baseline dyno pull will tell you whether you need to richen up or lean out at each of these target rpms where the torque has decreased. The goal is to have a flat horizontal torque curve sitting at peak torque for as long as possible without reducing your injector duty cycle too far, especially when VTEC has engaged. The goal is not a specific airel ratio. The airel ratio is the means to an end not the goal itself. It is only a compass that tells you the direction of fuel delivery to tune or dial in (i.e. richen more or lean out more at the target rpms). The torque will tell you whether to continue or stop. Get rid of the torque dips. However, I would not proceed past higher (leaner) than an airel ratio of 13.5:1 or if you already hear knocking. A caveat: You usually cannot hear knocking at high rpms anyway so don't base your decision on your ears. Some tuners have pushed to 14.0-14.5:1 in some all motor Hondas...I am a chicken. The way some fuel controllers work is by altering the manifold absolute pressure (MAP) signal to the ECU. The MAP is an indicator of air flow. To get the ECU to open the fuel injectors longer, the fuel controller changes the true incoming MAP signal to the ECU into a larger voltage. The ECU is tricked into thinking there's more air and adds the correct amount of fuel. Some fuel controllers max out at 12-14% increase, since >14% gain on the manifold absolute pressure voltage signal by the controller trips a check engine light because the ECU thinks you are running boost. If you have maxed out on the increase in fuel from the controller and may need a little more at the upper rpms, you can increase fuel pressure slightly to see if this gives you more fuel increase but unfortunately this increase will be across the entire rpm range. If you do need to up the fuel pressure regulator setting then, remember to adjust in the rpm areas where you need to lean down further afterwards. There is set limit on the fuel controllers as to how far you want to lean down. I've never used an exhaust gas temperature reading to tune my WOT fuel curves but some FI people combine it with the wideband readings for their tuning. You need to have the EGT probe placed 2 in. max. away from the exhaust manifold flange to get an accurate reading. This involves drilling a hole in a header primary near the flange: something most people won't want to do. 3. Cam Gear Tune: The 2 most dangerous situations are if you retard the intake or exhaust cam gear too much because these are cases when you decrease piston to valve clearance and risk piston to valve contact. Most people say do not push past 6-8 degrees unless you have measured clearances and know that it is safe to proceed past this point. Having said this though many of the top power makers I know have gone to 10 degrees or more (knowing and measuring ahead of time that it was safe to do so). a) If you want more midrange gains than upper rpm gains: Widen the lobe separation angle (reduce the overlap). Simultaneously retard the intake cam gear and advance the exhaust cam gear in 2 degrees increments for each setting (2 dyno pulls) until you no longer get any more gains. I would not go past 6-8 degrees retard unless you have measured piston to valve clearance (clay tested) and know for sure it is safe to go past these points. b) If you want more upper rpm power than midrange: Tighten the LSA (increase the overlap). Advance the intake cam gear in 2 degree increments until you no longer get any upper rpm gains. Now retard the exhaust cam gear in 2 degree increments. You have to be careful here because too much exhaust cam gear retard can lead to piston to exhaust valve contact. I would stop at 6 degrees advance, if you are unsure of your sclearances. Again you are doing at least 2 successive pulls for each setting and then stopping to allow the engine to cool down a bit. You want to find the best overlap for the highest gain in the rpm area you want. Stop when you see no further gains. 4. Tune the Ignition Timing After Each Intake Cam Gear Adjustment. The intake cam is directly connected to the distributor and affects spark timing. If you have changed the intake cam gear, you need to bring the spark timing back to your desired setting. Do not advance spark timing too far. It really depends on whether you have a J&S Safeguard to protect against detonation, the fuel octane rating available, and your compression ratio. Advancing ignition spark timing increases peak cylinder pressures and therefore, increases temperatures and runs a higher risk of detonation. If you have greater than 11.4:1 static CR without knowing the airel ratio across your entire rpms, I suggest that you do not exceed 16 degrees BTDC. For most of you with 9.2-10.9:1 static CR, IMHO there is no gain to going past the maximum factory spec of 18 degrees BTDC. Some do benefit at 19 degrees BTDC. Remember that advancing not only increases the risk of detonation but also increases the wear of engine parts from high spikes in peak cylinder pressures and temperatures. I would rather have my engine last longer than gain 3 extra whp from pushing advance on the spark timing. I have run as high as 21 degrees BTDC at 10.8:1 CR but I had bigger 270 cc/min injectors at the time and ran very very rich. I've always eventually turned the spark timing back down to 18 degrees BTDC for safety and longevity reasons. 5. Reality check Some people reset everything back to their original settings at the start of the session and do 2 pulls at the end of the session just to make sure the new settings improvements weren't due to heat sinking of the engine or things other than the settings themselves.It's a good quality control check for you to believe in your final dyno readings. cheers" Many thanks to my buddy Tuan, he deserves it! Hope I helped ya, A.