foxbat

I never said 'bad bearing" I said spun bearing, a bearing can be brand new & spin for a variety of reasons as I mentioned.
@kingTalon, for the benefit of this thread, explain what's the purpose of your self imposed limit of 9 degrees, is it out of fear of detonation (when using pump fuel such as 93oct) or is it to avoid the excess torque?
You said "Advanced timing hammers the rod bearing with excess cylinder pressure as the piston is nearing TDC" which translates to 'torque' I assume, so what if we use high oct fuels (knock free) such as E85 or C16 do we still abide by the 9 degrees limit out of fear that an advance timing would hammer the rod bearing?
I agree, I was only speculating when I said a spun bearing & that was based on the damage location (bottom of engine) besides the fact that his timing table looks conservative enough. Detonation would have likely damaged the top, pistons, rings, ring land, valves

KingTal0n

I used to think the same thing, because it rhymes with common sense. And I met some big name tuners that tuned like that for years who owned dynometers.

The thing is, you can't tell when 12 or 15* is hammering the engine bearings. The knock sensor doesn't count that as knock. You won't get any indication there is a peak pressure unnecessarily challenging the forward momentum of the crankshaft as it attempts to move through TDC and make use of that excess pressure.
This issue is also partially dependent on the rod ratio, or the angles formed by crank lever arm with rod. A longer rod allows more dwell at TDC, and more rotation angle through which the crankshaft can utilize high pressure near TDC. Which is seen as a really good thing- except that it also masks the situation where pre-TDC pressure is too high, because now the crank can barely rotate through TDC and start applying torque in the right direction once more, giving you "more torque to the wheels" even while the engine is in distress and the knock sensors aren't lighting up.

Thats the first scope of this passage: It's easy to over-time a modern combustion engine without realizing it. An engine can be in distress without pinging or detonation or knock.
Unless we put a combustion pressure analyzer on the engine, we eally can't tell by just looking at a dyno or driving the car, or data-logging.

Lets set that aside for a moment and talk about the real problem though, temperature, heat, turbochargers, gasoline.

Through experience I learned that an engine will get hot no matter what you do on pump gas if sustained at WOT, and applications where this is done using a turbocharger at WOT for extended periods are rare.
nevertheless, lets discuss the implications.

Whether we use 9* or 12* or 15*, on Gasoline, the EGT will still climb if keep an engine at WOT, until some steady state temperature.
The steady state exhaust temperature is partially dependent on the amount of power the engine makes, so saying it will stop at XXXX*F EGT is not possible.
The only way to solve this question is to calculate the total thermal contribution due to the number of Joules or Watts the engine is producing at max output, Or measure it empirically.
Then we would calculate max amount of time it needs to stay at Max Output to determine If a steady state forcing(forcing the EGT to go down) is required, and if so, there will be more to it than adjusting ignition timing, it will need water injection or improved fuel quality to bring the EGT down.

For example when tuning a Boat engine using 93 octane, The WOT period is sustained sometimes for over 2 minutes. If the EGT was climbing because of a blower/boost then there are all manner of tricks one could use to hold down EGT including water cooled exhaust manifolds. We wouldn't consider advancing the timing in this case- Ask yourself why not? Why when EGT is "high" in a blower/boost application does it not make any sense to add timing, yet it seems to be everyone's common sense to add timing to keep the egt "LOW" in the first place? There must be a fundamental flaw in our reasoning or common sense somewhere since the one does not directly guarantee the other. Timing and EGT are only partially dependent variables, having a high timing advance does not guarantee a low egt.

So lets look at typical consequences and more "common sense" approach to realize what is going on here.
Leading by example: 2.0L turbo engine typical example
15psi of boost it makes 350rwhp on gasoline at 6700rpm, If we load the engine at 15psi for 2 minutes at WOT and 5000rpm EGT climbs to 1380*F steady state
25psi of boost it makes 450rwhp on gasoline at 6900rpm, If we load the engine at 25psi for 2 minutes at WOT and 5000rpm EGT climbs to 1570*F steady state

I haven't said anything about timing yet- lets just assume the timing is optimal. Whatever it is, its perfect for the given EGT. And that is what I want to bring to attention, that the timing is partially dependent on the EGT because the EGT reflects the temperature of the combustion chamber (piston surface, valve, cylinder walls, residual heat) and the temperature of those components affects the volatility of the fuel. So, working backwards, the hotter the EGT goes the less timing we want for gasoline, because gasoline becomes more volatile when it warms up. Imagine spraying gasoline onto a hot frying pan vs a cold one. In the morning when you start the engine the piston is cold to the touch yet it runs pretty normal. So our perception of these engines is mostly from while they are cold- we start them cold, drive them warming up, and in a daily driver application rarely get the EGT hot enough to fully expand a low silicone forged piston. Which is why those pistons are not recommended for daily drivers, their piston wall clearance is so large and the engine barely warms up in traffic enough to fully expand in the bore before you reach destination, all it does it slap around and make a mess of the bore over time. So lets assume we are using a fragile cast piston with a low coefficient of expansion in these examples. To continue;

The EGT is so much higher in the higher output situation because the engine is producing more power, there is a higher mass of hot exhaust gas to deal with (overall more mass flow through the engine). And since we didn't make the engine bigger or adjust the thermal capacity of any of it's parts, the max temperature steady state will only go up and up and up as we add more and more power.

To control the rising EGT, a method is required such as water injection, or a superior fuel. Adding timing won't help because timing is already perfect. i.e. you can't look at a tune and say "oh it needs more timing to control EGT" or "hey lets add timing to keep it from getting hot" none of that has any bearing on reality because the total amount of power output is going to determine the max EGT seen based on the total time spent at WOT and how close to optimal the timing actually is.

So now, lets use a non-perfect scenario. Timing is rarely perfect.
Same example, 2.0L typical engine, 100% VE, etc... But this time lets pay attention to the torque curve and forget about power
15psi of boost with 13.0*, 337 ft*lbs of torque, jagged graph, max power because of erroneous spikes in curve, 1350*F EGT
15psi of boost with 11.0*, 330 ft*lbs of torque, a little spiky, 1360*F
15psi of boost with 9.0*, 324 ft*lbs of torque, smooth graph, 1380*F
15psi of boost with 7.0*, 287 ft*lbs of torque, spiky and falls over (something is clearly wrong), 1440*F

Let me show with a picture what is going on here


The dyno curve will often reveal a 'spikey' nature in the torque curve (which is taken from power measurement of a known weight roller being accelerated)
If the information is being captured quickly enough by the dynometer electronics it can reveal an oscillating power application to the roller, which I usually find attributed to timing related.
Using too much ignition timing often generates the higher peak numbers because of the oscillations causing little spikes.

There is more info here about tuning, and methanol, timing etc... and more examples
https://forums.nasioc.com/forums/sho...8&postcount=48

So a quick review,
-Extended periods of WOT reveal steady state EGT (the highest EGT known to hold steady at WOT)
-Gasoline is temperature sensitive, i.e. higher temperatures require reduced timing to compensate for increased reaction rate of the fuel
-auxiliary methods for controlling EGT are required, timing is not the "EGT CONTROL" people think it is

So looking back at my example engine using 9* one more time. I called it "ideal" even though the EGT was slightly higher and torque output was slightly lower.
1. When the engine is cold, 12* or even 15* is fine because there is no high steady state EGT present, and no significant warming of the engine. This can be misleading because an engine can still be "cold" after running for 30 minutes in traffic, where combustion chamber temp and (EGT) is still markedly "LOW" (say 450*F-650*F) It won't really get "HOT" until it is held at WOT or at least run 'harder' for a bit.
Once that happens, the fuel (gasoline) will no longer tolerate the high residual EGT, and timing needs to be reduced. Since our maps dont have "cold" and "hot" timing options for EGT, we should always opt for the lowest number it will ever require.
Looking at number one another way;
Lets say I start the engine cold and run 9* vs 12* and notice that the EGT climbs much more rapidly when using 9*.
I think this is where most of the confusion comes from. People, dyno operators, take note of that fact and assume 9* isn't enough.
Technically this is true for a cold engine, because when everything is cold the fuel is more comparable to higher quality fuels, i.e. it will tolerate more timing, and in turn this is reflected in reduced EGT rate because more of the power is extracted by the piston/rod and less leftover as heat going into the exhaust.
However the maximum EGT is going to 'stop' around the same number peak since it is partially dependent on power output, e.g. Watts or Joules of power being produced.
The 9* might raise the EGT faster, but overall the peak and steady state temperature is going to be relatively similar,
the main difference being that once the EGT has risen fully to its peak, the gasoline is no longer going to behave like it did when the engine was fully COOL and requires less timing.
As mentioned, modern combustion engines, especially well design turbo variants, are highly tolerant of a wide range of conditions, so they admirably tolerate excess timing and poor air fuel ratios,
with little to no warning to us owner/operators.

2. Another thing to consider is Volumetric efficiency in these examples.
9* is for 100% VE engines, i.e. engines with largeish camshafts taking full 100% cylinder at peak RPM.
For a stock engine, VE near redline is perhaps 70-80%, so 12* is acceptable. For 2jz-gte engines for example, with stock camshaft often need 13* for 18psi of boost on pump fuels by redline, because VE is dropping.
The 86x86 engines are very similar, even among different manufacturers, timing is set similarly, and the results have been impervious to fault in practical applications of daily driving.
Note that everything here is based on fragile cast pistons, and daily drivers. My picture shows the racing "timing" setting, and the reasoning: EGT is under control in racing situations, it is tightly measured and inspected, because EGT is an essential measurement to take when engines are very expensive. In racing you have all the necessary 'toys' and 'tools' for cooling the intake charge, cooling the fuels, using higher quality fuels, cooling the parts down enough that using a more advanced timing is acceptable.

Biggiesacks

If I'm not mistaken, the way Mitsubishi deals with controlling EGT is by having an extremely rich fuel map and then uses a decay mechanism that pulls fuel. It starts by pulling a bunch of fuel, and decays down (or up depending on how you think about it) to the rich fuel map. This mechanism is known as lean spool.

KingTal0n

please don't worry, I just thought it was really funny when the first guy said "I blew a rod (and obviously rod bearing went with it) out the side of the block", and then you came in with something like "You might have a bad rod bearing" or "I think the rod bearing is bad" rofl

I don't know why its so funny, I might have a twisted sense of humor.

Everything I stated is with respect to pump fuel 93 octane on mostly stock engines with basic (camshaft) upgrade. And I included an aside about using the stock camshaft above.
For fuel as E85 which not only cools the engine and air intake, you need experience because there is more to it than just "find the best number on a dyno" but luckily it isn't that involved,
basically my steps are,
1. Start out by comparing factory E85 timing maps with similar engines in production made through similar years, especially heavy vehicles and 4WD vehicles which will guarantee to load the engine with low rates of acceleration. This will give you an idea of what the engineers determined was a safe range for slow rate of acceleration.
Usually they are using a little more timing for E85 over pump, i.e. if the engine wanted 9* on pump 93 then I suspect 12* on E85. For a starting place to street tune.
2. Street tune the vehicle, leave it fat and leave the timing out of it. Check the plugs and use high quality plugs (iridium) right before the dyno
3. Dynotune the vehicle. this is where experience plays a role. If you know in advance the time-rate of acceleration in final gear of the vehicle on the street (you've taken logs and measured how long 1:1 gear lasts) and the vehicle is never going to be run in overdrive at WOT (that would accelerate even slower than 1:1) then you can safely compare the dyno roller weight to the actual vehicle weight, i.e. if the roller takes 5 seconds to spin from 3k to redline, and the real car takes 7 seconds to go the same rpm range, then you know the roller is accelerating faster. What that means is, to get the peak timing number out of the dynometer will require a little more timing than the car will need to accelerate fastest on the actual road. In other words, if you found "BMT" (Best Mean torque? Most torque with minimal timing) with the roller accelerating faster through a gear than the actual car does on the road, it will be overtimed and you may gradually weaken a piston/ringland due to excess pressure over time without realizing it. This in my opinion is a majority of sr 2.0L failures I have seen over the last 10 years, dyno tuning at 14-15* of timing for peak acceleration on a roller of unknown weight, then losing their ring lands or rod bearings 5-10 years later, whereas some sr20 engines with (good tuning) and factory tune seem to last forever.

4. As with anything else a bit of a caution goes a long way. If i know the roller is lighter, accelerates faster than the car will through a longest gear (the LONGEST gear), then obviously some timing will be removed.
If I know the owner will put it into overdrive and go WOT on the highway with it, then timing needs to be removed for that situation as well because the engine will accelerate even slower.
At the end of the session it comes down to how the car is configured and what sort of driving style.
If the engine is started cold, run 30 miles and shut off for 8 hours (drive to work) and then the same thing again, 5 days per week, and occasionally drove to the store on weekends. Then 9* on pump fuel will never be enough because the engine will always be operated while cold, it will run inefficiently everywhere it is taken because the owner is just using it for daily driving to and from work and the motor is too cool for such a conservative timing number.

KingTal0n

Various factory have all manner of strange mechanisms. I believe the sr20 does something similar. This is tuned into their base maps I believe to simply save fuel.
The EGT of an engine will not appreciably climb until WOT is held for a length of time, say 5 to 10 seconds, and for stock engines it could take even longer to get a high number (because output is low)
there is no danger of high EGT while not in BOOST, even for N/A engines run for long periods of time at WOT rarely have EGT related failures unless run lean WOT for extended periods (like any engine)

KingTal0n

It is worth repeating and clarification,

I did say above somewhere that trailing into ~10.2* of timing as approaching redline is typical after say 6500-7000rpm for tunes which require 9* in the mid-range.
My rough 9* approach is for engines at 100% VE in their midrange with say 18psi to 22psi of boost is typical.
As it passes 6400~ start to add another degree is typical. And by 8000rpm perhaps 10.8 total degrees, especially if spraying water/methanol would be fine IMO.

But I'd go out on a limb to say that when using pump fuel 93 octane (~92), over 18psi of boost @ 2.0L, for typical daily drivers (cast pistons with squirters), using more than 11* anywhere after 18psi is a death sentence at 9:1 compression, with all but the baddest of intercoolers and similar toys to keep the IAT and engine temps in check.
It will run fine, great. Even for maybe 5-10 years. Which can be misleading to the owner (it lasted 10 years so it just "wore out" theory)

What will happen is, most of the time it will run fine. But if you keep driving the car ALOT, all over the place, up hills and through hot weather, over time you it will enter conditions where the additional timing is unwanted. Conditions which can not be replicated on the dynometer or at a particular track. And nobody will be there to pull out a degree to save it that day.
To compare with the picture above, it was "tuned like a track car" (more timing, requires more 'toys') and then used as a daily driver, which it was tuned to aggressively to be safe for, didn't have the right 'toys'. Daily drivers endure more temperature fluctuations (they have poorer heat exchangers, or fewer, than track cars), sometimes worse conditions (sitting in traffic with the A/C on can significantly raise IAT, going uphill or a tank of bad gas can cause knock, etc) and more varied driving conditions (drive it slow, drive it fast, cruise in the city, cruise on the highway, WOT from a light, WOT from a highway speed) So there needs to be an additional degree of freedom in the timing map for those conditions. Many factory ECU have mind boggling settings which remove or add timing based on these widely varied situations. The track car, on the other hand, has a consistent set of steady state temperatures because all of the heat exchangers are upgraded and additional heat exchangers have been added as needed. The track car also has a consistent set of driving pace that is known beforehand, i.e. you know how long the track is, how many miles, how many turns, how fast the car will be going the whole time more or less. And the track car also receives better fuel, the chances of bad gas or poor octane is eliminated, nearly.

I hope this helps explain the difference between a 9* and 13*+ of timing settings for these applications.

ZZA

I agree, I've faced this issue where I would get random 6-9 counts of knock but on another day with a fresh tank of gas I'd get 0 counts. Yes base timing could've been off given the motor had 130k kilomters on the clock. I'm saving up towards a ross sport built 2.0 short block with a fp black turbo, and yes I will be adding a water meth kit as well. Also the 90-100 load cells I agree as well as I would see occasional counts of knock around that region when transitioning into boost and would get "shift knock" originating from those cells. Also I must add, my oil temperatures would skyrocket over 120C after a few pulls while coolant would stay under 100C which leads me to believe I might have had cooling issues or a failing waterpump which the coolant temperature sensor did not pick up.

nor11384

iTrader: (1)

Could someone explain this to me? Why does timing go up from 50 - 80 load/ 500 - 1000 rpm? I took this map off this thread so i can ask this question. All maps ive seen are somewhat like this. Also, why is timing lower than idle timing from 10 - 30 load/ 500 - 1000 rpms?




This is my timing map below... I went ahead and bumped up timing in this area since all maps seem to be like this. I thought maybe it would help with lean tip in but made no difference. Actually feels more jumpy at low rpms in a higher gear as opposed to how it was. Also, when i made this change i noticed that when letting off the gas the afrs dont go lean right away as they should (fuel cutting off). Instead, the car keeps moving forward as if i was still on the gas for 2 - 3 seconds and then it will go lean as you can feel the car slowing down as it should. For example, im in 5th gear on the highway and i let off the gas and car keeps moving forward a bit and then injecors will cut off and you can feel it. Does it have anything to do with this?

Evo VI.

Q.1 The higher timing values are to catch the idle as it falls rapidly when clutch in.

Q.2 This is done to introduce cam lope (wop wop) and also drops the idle rpm slightly.

Q.3 You would only hit this area and load on clutch in and rpm dropping so it wouldn’t cause what you describe.

what you describe would be fuel injector cut off points.
are you running oem Open loop values?

nor11384

iTrader: (1)

Ah makes sense. Thank you for the explanation. What do you mean by oem open loop values?

KingTal0n

w as rotating speed of engine (angular velocity)
As w approaches 0 rough timing ranges

RPM = timing range
2000rpm = 17-28*
1500rpm = 15-25
1000rpm = 12-23 "Standard"
800rpm = 8-21
500rpm = 5-18
200rpm = 1/100 to 10*
100rpm = -3 to -10*
50rpm = -10 to -25*
1rpm = -28 to -35*

Something like that. Need to emphasize that at some point there will be negative and zero values, especially if the engine is rotating very slowly say 1rpm, timing can be heavily RPM dependent at low w. If the engine was going to be fired from 0rpm, where to position the piston/rod after compression? It would have to be after top dead center.

Evo VI.

Open Loop = use the fuel map
Closed loop = let the O2 sensor feedback to ecu to decide what AFR.

standard values can be changed to get more control over AFR at anything over 25% throttle for eg.

nor11384

iTrader: (1)

Oh I know how it works just didn’t know what you meant. Well I’ve changed plenty lol. I’ve also seen a lot of fuel maps that have 13.3 at 500 rpm all the way up to like 100 load.wonder what that’s about.

ZZA

Work in progress but this is what I'm running on 91 octane 2.3L Stroker freshly built (1500 kms on it), stock evo 6 turbo. Peak load is 290 at 24 psi.

mines5

Start A/C and start logging and see where the active cell goes to