Ignition timing 101
#81
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I'm sorry if this question was already asked as I did not read through all the posts on the thread but what exactly does the knock sensor listen for then? Is it just the pinging frequency that is created from the onset of detonation?
#82
On The Tree
Join Date: May 2004
Location: Denver CO.
Posts: 104
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by MadBill
Excellent description, J-Rod!
I suspect a lot of the desire to advance spark to the border of detonation regardless of other factors (e.g. power) results from typical OEM engine design and calibration. When designing for a specific minimum fuel octane, it has been found by them that the best power and economy are achieved with slightly retarded ignition timing at a CR which is slightly too high to run knock-free at MBT. This means there will always be power to be gained by adding spark and either reducing the built-in 'insurance factor' or increasing octane. (typical approach of aftermarket chips/tunes)
If your particular combination's octane requirement is several full points below that of your selected fuel, you can advance well beyond MBT and lose significant power without a whisper of detonation.
Similar to 04Y's experience (but too many years before!) we started tweaking on my buddy's new 1970 GTO. With a tank full of Sunoco 260 (~106 Research octane) and a stop watch, we cranked the timing up 2 degrees at a time, waiting for knock to signal the end of our 'power gains'. At some point it dawned on us that we were at 46 degrees and had lost over a second and a half in our zero to 100 MPH runs. Turns out the old goat liked no more than ~ 37 degrees, and needed no more than 91 octane to use it...
I suspect a lot of the desire to advance spark to the border of detonation regardless of other factors (e.g. power) results from typical OEM engine design and calibration. When designing for a specific minimum fuel octane, it has been found by them that the best power and economy are achieved with slightly retarded ignition timing at a CR which is slightly too high to run knock-free at MBT. This means there will always be power to be gained by adding spark and either reducing the built-in 'insurance factor' or increasing octane. (typical approach of aftermarket chips/tunes)
If your particular combination's octane requirement is several full points below that of your selected fuel, you can advance well beyond MBT and lose significant power without a whisper of detonation.
Similar to 04Y's experience (but too many years before!) we started tweaking on my buddy's new 1970 GTO. With a tank full of Sunoco 260 (~106 Research octane) and a stop watch, we cranked the timing up 2 degrees at a time, waiting for knock to signal the end of our 'power gains'. At some point it dawned on us that we were at 46 degrees and had lost over a second and a half in our zero to 100 MPH runs. Turns out the old goat liked no more than ~ 37 degrees, and needed no more than 91 octane to use it...
So why do you lose power, assuming it's not caused by Knock. Is it because ignition occurs to early and therefore you don't optimize the power on the downstroke?
#84
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by Spinmonster
I'm sorry if this question was already asked as I did not read through all the posts on the thread but what exactly does the knock sensor listen for then? Is it just the pinging frequency that is created from the onset of detonation?
#85
On The Tree
Join Date: May 2004
Location: Denver CO.
Posts: 104
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
So bottom line, you have to adjust the advance curve throughout the RPM range to optimize the ignition point so you achieve optimum power without knock.
Most people I know are just setting the advance as far as it will go without knock and at the very least, they are not making any more power and could be making less power.
Is there any kind of generic advance curve for an LS1/LS6/LS2 motor? Something to start with?
Most people I know are just setting the advance as far as it will go without knock and at the very least, they are not making any more power and could be making less power.
Is there any kind of generic advance curve for an LS1/LS6/LS2 motor? Something to start with?
#86
11 Second Club
Join Date: Jul 2004
Location: Sydney, Australia
Posts: 121
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
My car was played with thoroughly on a dyno adding and subtracting timing. It like the most timing advance possible before knock started increasing and even made more power with scattered knock. This was with 29-30 deg advance and thats with a LS1 with 216 220 cam 114lsa and ported heads 10.7:1 - shorties 4 into 1s.
The car has now run 11.619 116mph at a race weight of 3625lb with driver.
The car has now run 11.619 116mph at a race weight of 3625lb with driver.
#87
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Here is a link to Allen Cline's article which supports J-Rod's information:
http://www.streetrodstuff.com/Articl...ne/Detonation/
I do recall a post by a GM engineer (I'm having difficulty finding it) that stated his research somewhat eroded the truism of 14 ATDC for LPP as being etched in stone for all motors, but not necessarily refuting the concept that LPP timing is of paramount importance.
Another related myth that seems to prevail is that throwing fuel at a motor with too much spark advance is the way to go. Klaus Allmendinger sums it up succinctly here:
http://www.innovatemotorsports.com/resources/rich.php
http://www.streetrodstuff.com/Articl...ne/Detonation/
I do recall a post by a GM engineer (I'm having difficulty finding it) that stated his research somewhat eroded the truism of 14 ATDC for LPP as being etched in stone for all motors, but not necessarily refuting the concept that LPP timing is of paramount importance.
Another related myth that seems to prevail is that throwing fuel at a motor with too much spark advance is the way to go. Klaus Allmendinger sums it up succinctly here:
http://www.innovatemotorsports.com/resources/rich.php
#88
TECH Fanatic
iTrader: (6)
Join Date: Jan 2002
Location: Springfield, IL
Posts: 1,194
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Nice article, they sum it up pretty well in the last paragraph. ![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
Is there any type of rule of thumb for timing as it relates to valve events? I realize the lobe shape will have an impact as well, but I'm referring more to optimal timing at XXXX RPM with something like an IVO of 6 BTDC. Is there an equation to figure this out?
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
Therefore a richer mixture releases less energy, lowering peak pressures and temperatures, and produces less power. A secondary side effect is of course also a lowering of knock probability. It's like closing the throttle a little. A typical engine does not knock when running on part throttle because less energy and therefore lower pressures and temperatures are in the cylinder.
#89
TECH Fanatic
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Hey Oztrack if you were making more power in the knock area perhaps you should try higher octane fuel. The fuel may be too volitile for the engine. Let us know if that makes any difference.
#90
Launching!
iTrader: (1)
![Thumbs up](https://ls1tech.com/forums/images/icons/icon14.gif)
Originally Posted by J-Rod
Allright, I see a LOT of mis-information on this topic. So, lets start a new topic here. Much of this is centered around the cylinder head itself. Much of it alos is based around the design of the engine. Hence the reason I am posting this here vs the tuning section.
Ok, when looking at an older style engine (say a a conventional 23 degree SBC). You have a cylinder head which is much less efficent than today's GenIII/GenIV. Unfortunately just like camshafts I see many folks assume that since they have always run X ammount of timing, they should just run that in an LSx motor.
I also see the common myth that you should keep adding advance to the car until it detonates, and then back it off a bit and call it good. Folks seem to believe that the more advance the better.
Nothing could be further from the truth.
Your motor needs a certain ammount of timing. But, adding more spark advance than it needs will cost you power...
A couple of important terms here.
Squish velocity
turbulence
wrinkled flame front
burn duration relationship
"Squish" creates small scale eddies that in turn create a wrinkled flame front, and this allows combustion to occur faster. Faster combustion is typically more efficient since there is less time for thermal (and other) losses. Higher levels of turbulence (and quicker burn duration) also allow one to advance spark retard closer to TDC.
Faster burn durations also decrease the chance of detonation. Detonation is a time and temperature dependent thing...the longer hot gasses 'cook' inside the combustion chamber, the more likely they are to auto-ignite, therefore, more squish actually decreases the chance of detonation. Faster burn will create higher peak cylinder pressures, however, and the engine can become noticeably rougher (i.e. like a diesel).
The optimal squish trade-off balances two main things: 1) Burn duration – the higher the squish velocity the faster the flame front (for a given operating condition and air/fuel ratio). Faster burn durations are typically more efficient and can wring more work out of a given air/fuel charge, 2) Heat transfer – higher gas velocities create more heat transfer and therefore reduce overall combustion efficiency. There are lots of other secondary factors as well such as Squish %, combustion chamber shape, etc…
One of the most important things folks overlook on timing is this...
Improving combustion efficiency allows timing retard, which then allows for combustion events at a later stage of piston rise (crank angle closer to zero). This then results in reduced 'negative' work 'against' the combustion cycle and improves BMEP and HP.
In other words, if you stop making more power at 22 degrees of timing, there is absolutely no point in going to 28 or 32....
One of the things we have going for us is that the Gen III / GEn IV has a good port/chamber design which is light years ahead of the stuff that is 50 years old... Automotive engineers have learned a lot, and now that innovation has made it into our cars.
This article has some good information on what optimal timing is. Read up on LPP and what it has to say. Think about that the next time you jack up your timing because its got to go faster, right...
http://www.germanmotorcars.com/Detonation.htm
All high output engines are prone to destructive tendencies as a result of over boost, mis-fueling, mis-tuning and inadequate cooling. The engine community pushes ever nearer to the limits of power output. As they often learn cylinder chamber combustion processes can quickly gravitate to engine failure. This article defines two types of engine failures, detonation and pre-ignition, that are as insidious in nature to users as they are hard to recognize and detect. This discussion is intended only as a primer about these combustion processes since whole books have been devoted to the subject.
First, let us review normal combustion. It is the burning of a fuel and air mixture charge in the combustion chamber. It should burn in a steady, even fashion across the chamber, originating at the spark plug and progressing across the chamber in a three dimensional fashion. Similar to dropping a pebble in a glass smooth pond with the ripples spreading out, the flame front should progress in an orderly fashion. The burn moves all the way across the chamber and , quenches (cools) against the walls and the piston crown. The burn should be complete with no remaining fuel-air mixture. Note that the mixture does not "explode" but burns in an orderly fashion.
There is another factor that engineers look for to quantify combustion. It is called "location of peak pressure (LPP)." It is measured by an in-cylinder pressure transducer. Ideally, the LPP should occur at 14 degrees after top dead center. Depending on the chamber design and the burn rate, if one would initiate the spark at its optimum timing (20 degrees BTDC, for example) the burn would progress through the chamber and reach LPP, or peak pressure at 14 degrees after top dead center. LPP is a mechanical factor just as an engine is a mechanical device. The piston can only go up and down so fast. If you peak the pressure too soon or too late in the cycle, you won't have optimum work. Therefore, LPP is always 14 degrees ATDC for any engine.
I introduce LPP now to illustrate the idea that there is a characteristic pressure buildup (compression and combustion) and decay (piston downward movement and exhaust valve opening) during the combustion process that can be considered "normal" if it is smooth, controlled and its peak occurs at 14 degrees ATDC.
Our enlarged definition of normal combustion now says that the charge/bum is initiated with the spark plug, a nice even burn moves across the chamber, combustion is completed and peak pressure occurs at at 14 ATDC.
Confusion and a lot of questions exist as to detonation and pre-ignition. Sometimes you hear mistaken terms like "pre-detonation". Detonation is one phenomenon that is abnormal combustion. Pre-ignition is another phenomenon that is abnormal combustion. The two, as we will talk about, are somewhat related but are two distinctly different phenomenon and can induce distinctly different failure modes.
Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. The initial combustion at the spark plug is followed by a normal combustion burn. For some reason, likely heat and pressure, the end gas in the chamber spontaneously combusts. The key point here is that detonation occurs after you have initiated the normal combustion with the spark plug.
Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.
Ok, when looking at an older style engine (say a a conventional 23 degree SBC). You have a cylinder head which is much less efficent than today's GenIII/GenIV. Unfortunately just like camshafts I see many folks assume that since they have always run X ammount of timing, they should just run that in an LSx motor.
I also see the common myth that you should keep adding advance to the car until it detonates, and then back it off a bit and call it good. Folks seem to believe that the more advance the better.
Nothing could be further from the truth.
Your motor needs a certain ammount of timing. But, adding more spark advance than it needs will cost you power...
A couple of important terms here.
Squish velocity
turbulence
wrinkled flame front
burn duration relationship
"Squish" creates small scale eddies that in turn create a wrinkled flame front, and this allows combustion to occur faster. Faster combustion is typically more efficient since there is less time for thermal (and other) losses. Higher levels of turbulence (and quicker burn duration) also allow one to advance spark retard closer to TDC.
Faster burn durations also decrease the chance of detonation. Detonation is a time and temperature dependent thing...the longer hot gasses 'cook' inside the combustion chamber, the more likely they are to auto-ignite, therefore, more squish actually decreases the chance of detonation. Faster burn will create higher peak cylinder pressures, however, and the engine can become noticeably rougher (i.e. like a diesel).
The optimal squish trade-off balances two main things: 1) Burn duration – the higher the squish velocity the faster the flame front (for a given operating condition and air/fuel ratio). Faster burn durations are typically more efficient and can wring more work out of a given air/fuel charge, 2) Heat transfer – higher gas velocities create more heat transfer and therefore reduce overall combustion efficiency. There are lots of other secondary factors as well such as Squish %, combustion chamber shape, etc…
One of the most important things folks overlook on timing is this...
Improving combustion efficiency allows timing retard, which then allows for combustion events at a later stage of piston rise (crank angle closer to zero). This then results in reduced 'negative' work 'against' the combustion cycle and improves BMEP and HP.
In other words, if you stop making more power at 22 degrees of timing, there is absolutely no point in going to 28 or 32....
One of the things we have going for us is that the Gen III / GEn IV has a good port/chamber design which is light years ahead of the stuff that is 50 years old... Automotive engineers have learned a lot, and now that innovation has made it into our cars.
This article has some good information on what optimal timing is. Read up on LPP and what it has to say. Think about that the next time you jack up your timing because its got to go faster, right...
http://www.germanmotorcars.com/Detonation.htm
All high output engines are prone to destructive tendencies as a result of over boost, mis-fueling, mis-tuning and inadequate cooling. The engine community pushes ever nearer to the limits of power output. As they often learn cylinder chamber combustion processes can quickly gravitate to engine failure. This article defines two types of engine failures, detonation and pre-ignition, that are as insidious in nature to users as they are hard to recognize and detect. This discussion is intended only as a primer about these combustion processes since whole books have been devoted to the subject.
First, let us review normal combustion. It is the burning of a fuel and air mixture charge in the combustion chamber. It should burn in a steady, even fashion across the chamber, originating at the spark plug and progressing across the chamber in a three dimensional fashion. Similar to dropping a pebble in a glass smooth pond with the ripples spreading out, the flame front should progress in an orderly fashion. The burn moves all the way across the chamber and , quenches (cools) against the walls and the piston crown. The burn should be complete with no remaining fuel-air mixture. Note that the mixture does not "explode" but burns in an orderly fashion.
There is another factor that engineers look for to quantify combustion. It is called "location of peak pressure (LPP)." It is measured by an in-cylinder pressure transducer. Ideally, the LPP should occur at 14 degrees after top dead center. Depending on the chamber design and the burn rate, if one would initiate the spark at its optimum timing (20 degrees BTDC, for example) the burn would progress through the chamber and reach LPP, or peak pressure at 14 degrees after top dead center. LPP is a mechanical factor just as an engine is a mechanical device. The piston can only go up and down so fast. If you peak the pressure too soon or too late in the cycle, you won't have optimum work. Therefore, LPP is always 14 degrees ATDC for any engine.
I introduce LPP now to illustrate the idea that there is a characteristic pressure buildup (compression and combustion) and decay (piston downward movement and exhaust valve opening) during the combustion process that can be considered "normal" if it is smooth, controlled and its peak occurs at 14 degrees ATDC.
Our enlarged definition of normal combustion now says that the charge/bum is initiated with the spark plug, a nice even burn moves across the chamber, combustion is completed and peak pressure occurs at at 14 ATDC.
Confusion and a lot of questions exist as to detonation and pre-ignition. Sometimes you hear mistaken terms like "pre-detonation". Detonation is one phenomenon that is abnormal combustion. Pre-ignition is another phenomenon that is abnormal combustion. The two, as we will talk about, are somewhat related but are two distinctly different phenomenon and can induce distinctly different failure modes.
Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. The initial combustion at the spark plug is followed by a normal combustion burn. For some reason, likely heat and pressure, the end gas in the chamber spontaneously combusts. The key point here is that detonation occurs after you have initiated the normal combustion with the spark plug.
Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.
![The Patriot !!](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_patriot.gif)
The following users liked this post:
musthaveLSx (01-02-2021)
#91
6600 rpm clutch dump of death Administrator
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Check out this month's GMHTP. They did a test of a 6.0L motor with several cams in additon, they swapped to a carb manifold and a carb which has much shorter runners than the stock plastic intake which came off the motor.
The net result was needing an additional 10 degrees of ignition timing to make up for the manifold change. It all comes back to combination....
The net result was needing an additional 10 degrees of ignition timing to make up for the manifold change. It all comes back to combination....
#92
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by J-Rod
Check out this month's GMHTP. They did a test of a 6.0L motor with several cams in additon, they swapped to a carb manifold and a carb which has much shorter runners than the stock plastic intake which came off the motor.
The net result was needing an additional 10 degrees of ignition timing to make up for the manifold change. It all comes back to combination....
The net result was needing an additional 10 degrees of ignition timing to make up for the manifold change. It all comes back to combination....
![Grin](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_grin.gif)
#93
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
It's already been touched on, but something that's good to mention is that very heavy loads will induce knock in motor that otherwise runs fine. If you're tuning a truck that will be used for towing once in a while, loading it without the trailer it'll be fine and won't have any issues, but with the trailer, it might knock and ping all over the place.
Just another reason not to use any more timing than necessary, I guess.
Just another reason not to use any more timing than necessary, I guess.
![Nod](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_nod.gif)
#94
6600 rpm clutch dump of death Administrator
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
bump for htis thread since there seems to be some questions about timing and spark in advanced tech these days...
Search is your friend...
Search is your friend...
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
#95
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Good thread... I thought I might add to something J-Rod commented on. To expand, the reason the pistons don't melt at 1800 °F is because the pistons are manufactured from aluminum.
The boundary layer on the piston is developed from normal oxidation (just sitting in normal atmosphere). While the true melting temperature of pure aluminum is 1220.58 °F this very small oxidation layer is extremely tough and usually requires temperatures in the area of 2300 °F to burn off. This is also why other areas in the combustion chamber show signs of damage before the face of the piston does. The face has no mechanical friction to wear off this protective layer. The sides of the pistons and areas that see more mechanical friction wears down the oxidation layer and is where the piston will be more susceptible to heat damage.
The boundary layer on the piston is developed from normal oxidation (just sitting in normal atmosphere). While the true melting temperature of pure aluminum is 1220.58 °F this very small oxidation layer is extremely tough and usually requires temperatures in the area of 2300 °F to burn off. This is also why other areas in the combustion chamber show signs of damage before the face of the piston does. The face has no mechanical friction to wear off this protective layer. The sides of the pistons and areas that see more mechanical friction wears down the oxidation layer and is where the piston will be more susceptible to heat damage.
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
#96
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Check out this month's GMHTP. They did a test of a 6.0L motor with several cams in additon, they swapped to a carb manifold and a carb which has much shorter runners than the stock plastic intake which came off the motor.
The net result was needing an additional 10 degrees of ignition timing to make up for the manifold change. It all comes back to combination....
The net result was needing an additional 10 degrees of ignition timing to make up for the manifold change. It all comes back to combination....
Anytime you can stuff more air into the engine the fuel will follow..Get the fuel that the motor wants and then you can put timing in it to clean up the graph and find peak and best power numbers.
I was on the dyno last Friday with a D1 blown 352ci LS1 that made 960hp before running out of exhausting ability...IE the EGR effect. The most powerful D1 known to date via Procharger actually. The ending average power numbers ended up being just shy of 924hp over a span of 6000 rpms to 7400. Changing to 2" primaries with a 3.5" collector, porting the carb bonnet, and adding a 1" plenum spacer should really put us up over 1000 hp mark. This setup is even air to water but we are not using ice. Just straight faucet water to make the power we have made so far so we know power is there when we run it on ice at the track.
The first thing we did was put a base timing curve in it and use fuel to see what the motor would like. Stopped on the fuel jets in the carb, and then added 2 degrees of timing from 22 base. Each 2 degrees was picking up 40hp and giving the graph the shape we were after. From 24 we went to 25 and picked up another 30. We knew we were getting close. A total of 4 degrees timing from base and the peak numbers were up 100 on both peak torque and hp but also the whole average power curve came up as well because timing cleaned the shape up the graph up. Fuel curve is always good to start with first before playing with timing. A big mistake I see many "tuners" try to do is just play with timing without looking at the combo and adding more fuel via main booster or IFR tables. They usually try only at PE vs RPM and the power gains indeed suffer and leave a lot to be desired for the mods.
![Secret2](https://ls1tech.com/forums/images/smilies/LS1Tech/secret.gif)
#97
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Ok so I need some guidance ! I have a 408 ls2 with procharger (d3M) and lingfelter blower cam and 8.5:1 compression lowered using the truck aluminum heads ported and polished ....
I went to a tuner and we started with the whole 22 degrees timing and was only making 350 - 400 hp up to 4000 rpm ( was limited due to blower belt slip at the time )... Now... I know these motors dont require as much timing but how does the lower compression affect that ? Is there a rule about where to start timing at 100 kpa on a lowered compression ls based engine ? and then adjust from that number 1 degree for every pound of boost added to the engine ? But whats my starting point ? any suggestions from people with experience with this PLEASE post ! THANKS !
I went to a tuner and we started with the whole 22 degrees timing and was only making 350 - 400 hp up to 4000 rpm ( was limited due to blower belt slip at the time )... Now... I know these motors dont require as much timing but how does the lower compression affect that ? Is there a rule about where to start timing at 100 kpa on a lowered compression ls based engine ? and then adjust from that number 1 degree for every pound of boost added to the engine ? But whats my starting point ? any suggestions from people with experience with this PLEASE post ! THANKS !
Last edited by monsterchevylizzard; 11-04-2013 at 03:29 PM.
#98
FormerVendor
iTrader: (1)
Join Date: Nov 2008
Location: Santa Ana, CA. USA
Posts: 2,157
Likes: 0
Received 17 Likes
on
17 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
First I would start with 16-18 degrees at WOT.
The ability to create your answer should be supported by more facts.
One simple report would be to multiply your C.R. (8.5) x your Density Ratio (1.2?) = 10.2
A compressor map would state your Pressure Ratio then add correction for Air Temperature.
Now for Joe, Knock Detection is more simple WHEN "Tooth Acceleration Measurement" is reported with my 60-2 TW fitted to a crankshaft.
The cylinder(s) individually show a change with Knock, yes around peak pressure, at this spot.
That change is a lower value in acceleration.
Thus each cylinders acceleration can be evened out by advance value changes.
Lance
The ability to create your answer should be supported by more facts.
One simple report would be to multiply your C.R. (8.5) x your Density Ratio (1.2?) = 10.2
A compressor map would state your Pressure Ratio then add correction for Air Temperature.
Now for Joe, Knock Detection is more simple WHEN "Tooth Acceleration Measurement" is reported with my 60-2 TW fitted to a crankshaft.
The cylinder(s) individually show a change with Knock, yes around peak pressure, at this spot.
That change is a lower value in acceleration.
Thus each cylinders acceleration can be evened out by advance value changes.
Lance
#99
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Here's the REAL article that J-Rod blatantly plagiarized.
http://www.contactmagazine.com/Issue...ineBasics.html
Nice copy and paste, J-Rod. I see you changed a few words in the process lol. That also explains why your responses to anything after the pasted article aren't near as technical. None of it was yours.
Seriously man. That's messed up. Even if it was 14 years ago. This thread last got brought up way, more recently than that so it could come up again in the future. People should know the truth.
He didn't write any of that, it appears. Unless he's Allen W. Cline. I suspect that if he was, he would've credited himself when quoting his own published article.
http://www.contactmagazine.com/Issue...ineBasics.html
Nice copy and paste, J-Rod. I see you changed a few words in the process lol. That also explains why your responses to anything after the pasted article aren't near as technical. None of it was yours.
Seriously man. That's messed up. Even if it was 14 years ago. This thread last got brought up way, more recently than that so it could come up again in the future. People should know the truth.
He didn't write any of that, it appears. Unless he's Allen W. Cline. I suspect that if he was, he would've credited himself when quoting his own published article.
#100
6600 rpm clutch dump of death Administrator
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Ls2Bias if you will notice in my original post there is a hyperlink to the original article (which is now no longer available). This is why I posted it on ls1tech along with minor edits to make it more readable on this site. Sites and content have a bad habit of disappearing over time. So, in this case I did copy content into the site so it wouldn't get lost over time (which is exactly what happened).
Here is a direct quote from my original post.
You are absolutely correct that I did not cite Allen W. Cline, but the reader was directed to the original source of the material I sourced from. I also did not cite it as my own work. So, I'm not sure why you decided to troll a 15 year old post, on your first post on this site but your fundamental assertion is incorrect. I have however edited the post to reflect it is an article by Mr. Cline.
Here is a direct quote from my original post.
This article has some good information on what optimal timing is. Read up on LPP and what it has to say. Think about that the next time you jack up your timing because its got to go faster, right...
Last edited by J-Rod; 06-04-2019 at 03:40 PM.
The following users liked this post:
Metalchipper (04-01-2021)