help me with knock retard
Lets start with this one.
This shows how EGT and spark timing intertwine compared to performance goals. With stock engines, we want ignition timing in the green area (daily drivers); far from the advanced timing that a competition engine would desire. As you leave daily driver town, you move to the left seeking performance boosts (squeezing the timing for nickles and dimes of power). As you acquire toys which assist with the combustion temperature (meth/water, coatings, shields, more efficient plumbing, bigger cooling systems, massive fans) you can keep moving to the left with less risk.
Until, of course, at some point, you go too far and wind up with a broken engine. Do not seek these nickles and dimes unless you are competition state (for money, fame, both) because the risk outweighs the benefit. Instead, stay close to the green area (EGT ramp). You can find the ramp by gradually reducing timing until the EGT suddenly begins to climb significantly. Stay off the ramp, but stay as close to it as you need to make sure your worst case scenario does not push you too far towards the danger zone. You only need to stay as close to the egt ramp as necessary to avoid damaging the engine when conditions are at their worst. As conditions worsen for your fuel (temps rise, a couple of wot runs later, your cooling systems are being taxed and perhaps insufficient) everything will shift to the left by itself, and luckily, you have all that headroom. Competition vehicles have the toys to keep the temp rise in check, thus they have less risk of shifting into the danger zone (so they can run closer to it with less risk)
In other words, To increase power with mostly stock engines, don't try timing the engine like a race car. Instead, we desire increased engine mass flow with forced induction or similar, and further reduced timing while adding more fuel to keep EGT down. A combination of low EGT and minimal timing advance will support the most safe power, there is nothing wrong with reducing timing as long as EGT stays in check. We use a dyno to expose hidden power between the EGT ramp and the most safe timing desirable, for example if you add 3* of timing and gain 20 horsepower, thats a pretty good trade. EGT should have dropped a bit. On a 500bhp engine this is not uncommon to experience if you started out with severely reduced timing. On the other hand, if you add 3* and gain 2 horsepower, EGT does not move, then you are too far on the left from the "ramp" above, pull it back several degrees and run again. Never leave it "On the fringe of too much advance" and let the knock sensor "fix it when it needs to", unless these occasions are very rare or unavoidable. You don't want the knock sensor doing anything, ever, except warning you when you get a bad tank of fuel.
This shows how EGT and spark timing intertwine compared to performance goals. With stock engines, we want ignition timing in the green area (daily drivers); far from the advanced timing that a competition engine would desire. As you leave daily driver town, you move to the left seeking performance boosts (squeezing the timing for nickles and dimes of power). As you acquire toys which assist with the combustion temperature (meth/water, coatings, shields, more efficient plumbing, bigger cooling systems, massive fans) you can keep moving to the left with less risk.
Until, of course, at some point, you go too far and wind up with a broken engine. Do not seek these nickles and dimes unless you are competition state (for money, fame, both) because the risk outweighs the benefit. Instead, stay close to the green area (EGT ramp). You can find the ramp by gradually reducing timing until the EGT suddenly begins to climb significantly. Stay off the ramp, but stay as close to it as you need to make sure your worst case scenario does not push you too far towards the danger zone. You only need to stay as close to the egt ramp as necessary to avoid damaging the engine when conditions are at their worst. As conditions worsen for your fuel (temps rise, a couple of wot runs later, your cooling systems are being taxed and perhaps insufficient) everything will shift to the left by itself, and luckily, you have all that headroom. Competition vehicles have the toys to keep the temp rise in check, thus they have less risk of shifting into the danger zone (so they can run closer to it with less risk)
In other words, To increase power with mostly stock engines, don't try timing the engine like a race car. Instead, we desire increased engine mass flow with forced induction or similar, and further reduced timing while adding more fuel to keep EGT down. A combination of low EGT and minimal timing advance will support the most safe power, there is nothing wrong with reducing timing as long as EGT stays in check. We use a dyno to expose hidden power between the EGT ramp and the most safe timing desirable, for example if you add 3* of timing and gain 20 horsepower, thats a pretty good trade. EGT should have dropped a bit. On a 500bhp engine this is not uncommon to experience if you started out with severely reduced timing. On the other hand, if you add 3* and gain 2 horsepower, EGT does not move, then you are too far on the left from the "ramp" above, pull it back several degrees and run again. Never leave it "On the fringe of too much advance" and let the knock sensor "fix it when it needs to", unless these occasions are very rare or unavoidable. You don't want the knock sensor doing anything, ever, except warning you when you get a bad tank of fuel.
Last edited by kingtal0n; Mar 5, 2016 at 10:50 PM.
Originally Posted by kingtal0n
definitely dont worry about what sensor is in there. If the A/F value is ok and you just want to go for a quick drive to re-check, then reducing timing is a fast, easy, safe first attempt at sorting out a suspected knock signal. Always choose the cheapest/quickest method first.
Originally Posted by kingtal0n
Mainly we are looking for oil, or obvious problems, like chunks missing or melted flakes of piston. The white overall color a nice indicator of economical use of fuel. A good compression test on each cylinder would also be nice to have for record, you should be keeping a log over the years, each year do a test and write it down for each cylinder to the best digit i.e. 145.0psi, 146.3psi, get as accurate as possible. As long as there is no oil and no melted/trouble plugs you can proceed with the wide open throttle runs, data logging, tuning
If you need a more graphical description of my timing discussion from above I can post a picture instead of more words
If you need a more graphical description of my timing discussion from above I can post a picture instead of more words
He already confirmed the knock retard went away with reduced timing, so it appears to be working. The next step is to confirm that it was really knock. If the sensor seems inconsistent he can change it at any time. We should never ASSUME a part is broken without doing everything in our power to confirm that it really is broken, or at least log its behavior so that we can compare with the new sensor. If he installed a brand new sensor now and it produces the exact same knock logs will you pay him back for it?
I would never tell somebody to change a part that appears to be working, unless there were no other options or it appeared faulty with some evidence. You don't go around prescribing antibiotics and doing heart surgery to everybody with a chest pain without doing everything you can to find the cause first.
Furthermore, if you know how to read a plug then why not help this fellow read his plug? All you have done so far is complain and bitch about my procedure without providing any alternative or insight. Theres a word for that...
Last edited by kingtal0n; Mar 6, 2016 at 11:53 PM.
You don't need an EGT gauge. I was only showing you how the engine works from the EGT perspective. With a mostly stock engine, you don't need it as bad as you need to hit the dyno for a final cleaning up (a slight advance to the timing, a slight leaning of the air fuel ratio, see how the engine responds) this will not yield alot of power but it will give you insight to how much you can gain (not much with a mostly stock engine) with these small adjustments and help you realize why we don't need to push them so hard forward.
