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Engine/Transmission (1994 - 1998) Timing
- Thread starter BDech
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It's hard to say on throttle response but it did idle smoother and was more responsive in the upper RPMs. I don't know if it did anything for EGT's as I didn't do any tests really. My mileage improved of course.
Just took my 96 from 14° to 16°... Didnt notice too much change at low rpm, but high rpm comes up much quicker, and I lost at least 200° on my EGT. I was thinkin about going for a higher timing, but with no real mods so far, I didnt want to push it. . If you already have a plate, and getting a 3k, I`d go for about 17° to keep her cool... 17 shouldnt be too steep...
good luck
-jerry
good luck
-jerry
Are you guys assuming that combusion temperature is lower with advanced timing just because your EGT's are lower?
I can't find a reason why it would reduce combustion temperatures.
I can see how it would lower EGT's by placing more time between ignition and when the exhaust gas hits the EGT probe, giving it more time to cool and give us the perception of safe temps inside the cylinder.
I have played with a lot of gasoline engines, and I don't see how the situation would be different there than in a diesel. Accepted safe EGTs for a gas engine are about 1600 degrees. I like to run a lot of boost on pump gas, so I have to retard my ignition timing to prevent detonation. When I retard my timing, my EGTs go up accordingly, because there is LESS time between ignition and when that exhaust hits the probe. In reality, the actual temperature in the cylinder is the same, but the temp I see is higher. I regularly see temps of 2000 degrees, but that's only because I'm flame broiling my probe with minimal timing. At the same time, people I know that run lots of timing and get a bunch of detonation break and melt pistons, even though they have 1500 degree EGTs. I have yet to break or melt anything. As far as I'm concerned, EGT's just an indication of timing, and are useless for tuning for that reason.
On a diesel engine, I wouldn't run without one, but I'd be careful assuming you can add more fuel or something like that because you advanced your timing and now have lower EGTs. I'd say your combustion temps are the same, you shouldn't assume it's cooler.
I can't find a reason why it would reduce combustion temperatures.
I can see how it would lower EGT's by placing more time between ignition and when the exhaust gas hits the EGT probe, giving it more time to cool and give us the perception of safe temps inside the cylinder.
I have played with a lot of gasoline engines, and I don't see how the situation would be different there than in a diesel. Accepted safe EGTs for a gas engine are about 1600 degrees. I like to run a lot of boost on pump gas, so I have to retard my ignition timing to prevent detonation. When I retard my timing, my EGTs go up accordingly, because there is LESS time between ignition and when that exhaust hits the probe. In reality, the actual temperature in the cylinder is the same, but the temp I see is higher. I regularly see temps of 2000 degrees, but that's only because I'm flame broiling my probe with minimal timing. At the same time, people I know that run lots of timing and get a bunch of detonation break and melt pistons, even though they have 1500 degree EGTs. I have yet to break or melt anything. As far as I'm concerned, EGT's just an indication of timing, and are useless for tuning for that reason.
On a diesel engine, I wouldn't run without one, but I'd be careful assuming you can add more fuel or something like that because you advanced your timing and now have lower EGTs. I'd say your combustion temps are the same, you shouldn't assume it's cooler.
MatthewPark said:
Read THIS
Nobody is assuming anything, they are taking their info from facts. Of course cylinder temps/pressures are going to go up, starting that burn much earlier is going to create more heat/pressure than a lower timing setting.
It is always a good idea to advance timing when more fuel is added cuz the fuel needs more time to burn. If you don't advance it, then the fuel will still be burning as it is exiting the combustion chamber hence hotter EGTs.
>Of course cylinder temps/pressures are going to go up, starting that burn much earlier is going to create more heat/pressure than a lower timing setting.
That's what I was saying. Aren't those temperatures relative to the ones that can melt your pistons? Isn't that why we use EGT gauges? If we already are at the safe limit, it says right on that page that advancing the timing pushes your engine further by creating more heat and cylinder pressure. From that information, I can only assume that safe operating EGTs have to be lowered slightly when timing is advanced.
My EGTs now never get over 1200. If I advance my timing, my EGTs might drop to 1100 or 1150. I might think "hey, now I can add more fuel in because my EGTs are lower, and I should get them back to 1200". I think that would be a bad plan.
That's what I was saying. Aren't those temperatures relative to the ones that can melt your pistons? Isn't that why we use EGT gauges? If we already are at the safe limit, it says right on that page that advancing the timing pushes your engine further by creating more heat and cylinder pressure. From that information, I can only assume that safe operating EGTs have to be lowered slightly when timing is advanced.
My EGTs now never get over 1200. If I advance my timing, my EGTs might drop to 1100 or 1150. I might think "hey, now I can add more fuel in because my EGTs are lower, and I should get them back to 1200". I think that would be a bad plan.
Aren't those temperatures relative to the ones that can melt your pistons? Yes, but piston temps don't rise as fast as the EGTs do.
If we already are at the safe limit, it says right on that page that advancing the timing pushes your engine further by creating more heat and cylinder pressure.
Yes, it does say that... . and your point is. . ??? Anytime you give an engine performance mods that give it more fuel and air, your decreasig the engines lifespan, but it all depends on what you do to it. Take a Top Fuel Dragster for example. They tear the engine down after EVERY pass because of the mount of fuel being thrown at it, the HP they make, and the temps/pressures that they gaskets, pistons, etc. see. Now compare that to a Pro-stock dragster and the only things they change are the valve springs after every pass. They only make so much HP from the specs that are allotted to them so those engines can go a few more passes without reconditioning the bottom end with new rings, sleeves, or bearings.
From that information, I can only assume that safe operating EGTs have to be lowered slightly when timing is advanced.
There's no assuming, when it says it and explains it right there.
If I advance my timing, my EGTs might drop to 1100 or 1150. I might think "hey, now I can add more fuel in because my EGTs are lower, and I should get them back to 1200". I think that would be a bad plan.
How would that be a bad plan? All it's going to do is raise the cylinder temps/pressures a bit, not enough to make the engine blow the head right off the block or let alone blow a head gasket. That is just the characteristic of starting the burn earlier. It's like removing things off of a balance beam, what you take off on one side you have to add to the other to keep it balanced. The affects of advancing timing is just one of those things one has to live with. If you have all the proper precautions, like ability to get the air in and out effiecently with a heavy amount of fuel and with a head gasket or bottom end that can take the extra air and fuel then the engine will last fine, but of course not as long a bone stock engine, which brings us back to the statement of advancing the timing pushes your engine further by creating more heat and cylinder pressure.
If we already are at the safe limit, it says right on that page that advancing the timing pushes your engine further by creating more heat and cylinder pressure.
Yes, it does say that... . and your point is. . ??? Anytime you give an engine performance mods that give it more fuel and air, your decreasig the engines lifespan, but it all depends on what you do to it. Take a Top Fuel Dragster for example. They tear the engine down after EVERY pass because of the mount of fuel being thrown at it, the HP they make, and the temps/pressures that they gaskets, pistons, etc. see. Now compare that to a Pro-stock dragster and the only things they change are the valve springs after every pass. They only make so much HP from the specs that are allotted to them so those engines can go a few more passes without reconditioning the bottom end with new rings, sleeves, or bearings.
From that information, I can only assume that safe operating EGTs have to be lowered slightly when timing is advanced.
There's no assuming, when it says it and explains it right there.
If I advance my timing, my EGTs might drop to 1100 or 1150. I might think "hey, now I can add more fuel in because my EGTs are lower, and I should get them back to 1200". I think that would be a bad plan.
How would that be a bad plan? All it's going to do is raise the cylinder temps/pressures a bit, not enough to make the engine blow the head right off the block or let alone blow a head gasket. That is just the characteristic of starting the burn earlier. It's like removing things off of a balance beam, what you take off on one side you have to add to the other to keep it balanced. The affects of advancing timing is just one of those things one has to live with. If you have all the proper precautions, like ability to get the air in and out effiecently with a heavy amount of fuel and with a head gasket or bottom end that can take the extra air and fuel then the engine will last fine, but of course not as long a bone stock engine, which brings us back to the statement of advancing the timing pushes your engine further by creating more heat and cylinder pressure.
>Aren't those temperatures relative to the ones that can melt your pistons? Yes, but piston temps don't rise as fast as the EGTs do.
Of course they don't. There is a ton more metal in a piston then there is in my EGT probe. More mass takes more energy to heat. If you are doing short pulls it probably isn't an issue. He is talking about hauling a trailer. It may take longer to heat up, but at some point it IS going to heat up.
>Yes, it does say that... . and your point is. . ??? Anytime you give an engine performance mods that give it more fuel and air, your decreasig the engines lifespan,
I'm not talking about whether your motor is going to last 400K or 800K. I'm talking about melting your pistons. We all know that making moer power reduces engine life. That's not the issue. The issue is creating more heat, but having the perception of less heat.
Why do you have a pyrometer on your truck? EGT's aren't an issue because our exhaust manifolds melt. They are an issue because our pistons can melt. It says right on that page that YOU linked me to that adding timing INCREASES heat inside the cylinder, and REDUCES EGTs. If all you are concerned about is your exhaust temps, fine. I care about what the temperature is inside my cylinder, where all of those expensive parts are.
>How would that be a bad plan? All it's going to do is raise the cylinder temps/pressures a bit, not enough to make the engine blow the head right off the block or let alone blow a head gasket.
Cummins says our motors can run all day at 1200 (because with higher EGTs cylinder temps will be too high). Let's say at 1250 for 2 minutes, they melt pistons (they won't, but that's not my point. ) You have enough fuel and air in there for 1200 degrees. Now you advance the timing. Your EGT's drop, but cylinder temp is up. Maybe to the point of melting something.
Of course they don't. There is a ton more metal in a piston then there is in my EGT probe. More mass takes more energy to heat. If you are doing short pulls it probably isn't an issue. He is talking about hauling a trailer. It may take longer to heat up, but at some point it IS going to heat up.
>Yes, it does say that... . and your point is. . ??? Anytime you give an engine performance mods that give it more fuel and air, your decreasig the engines lifespan,
I'm not talking about whether your motor is going to last 400K or 800K. I'm talking about melting your pistons. We all know that making moer power reduces engine life. That's not the issue. The issue is creating more heat, but having the perception of less heat.
Why do you have a pyrometer on your truck? EGT's aren't an issue because our exhaust manifolds melt. They are an issue because our pistons can melt. It says right on that page that YOU linked me to that adding timing INCREASES heat inside the cylinder, and REDUCES EGTs. If all you are concerned about is your exhaust temps, fine. I care about what the temperature is inside my cylinder, where all of those expensive parts are.
>How would that be a bad plan? All it's going to do is raise the cylinder temps/pressures a bit, not enough to make the engine blow the head right off the block or let alone blow a head gasket.
Cummins says our motors can run all day at 1200 (because with higher EGTs cylinder temps will be too high). Let's say at 1250 for 2 minutes, they melt pistons (they won't, but that's not my point. ) You have enough fuel and air in there for 1200 degrees. Now you advance the timing. Your EGT's drop, but cylinder temp is up. Maybe to the point of melting something.
You really need to read more, Matt.
How many guys on here are running 16*+ of timing and melting pistons because of the timing advancement? Ummm, I'm gonna have to say about none.
You keep repeating everything I am saying and making it seem like I don't know what I am talking about. I am a mechanical engineer, I went to school for this kind of thing.
Duh, EGTs are an issue when you add more fuel, that's why I have a gauge to monitor the temps. I'm not gonna toss serious performance mods on to an engine and not montior what its doing.
Why do you think I linked you to that page, so I wouldn't have to explain to you what I already know. Where did I ever disagree with anything that the page I linked you to, said?
Research, man, research.
Sorry, for hijacking this thread with arguments over assumptions vs. facts.
How many guys on here are running 16*+ of timing and melting pistons because of the timing advancement? Ummm, I'm gonna have to say about none.
You keep repeating everything I am saying and making it seem like I don't know what I am talking about. I am a mechanical engineer, I went to school for this kind of thing.
Duh, EGTs are an issue when you add more fuel, that's why I have a gauge to monitor the temps. I'm not gonna toss serious performance mods on to an engine and not montior what its doing.
Why do you think I linked you to that page, so I wouldn't have to explain to you what I already know. Where did I ever disagree with anything that the page I linked you to, said?
Research, man, research.
Sorry, for hijacking this thread with arguments over assumptions vs. facts.
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Well. . it's not a good idea to knock his point of view, even if you are a Mech. engineer.
Also, if you think that no-one running a timing advance has melted a piston, you need to look at some of the posts in the competition forum that came up after the lincoln co. atpa pull this year in Stanford. I'll find the link later but the ferd with the cummins in it was running with half a piston (and I wondered why it sounded strange). You won't find many burnt down trucks like that , but the pics totally and completely back his statement about higher cylinder temps.
Also, if you think that no-one running a timing advance has melted a piston, you need to look at some of the posts in the competition forum that came up after the lincoln co. atpa pull this year in Stanford. I'll find the link later but the ferd with the cummins in it was running with half a piston (and I wondered why it sounded strange). You won't find many burnt down trucks like that , but the pics totally and completely back his statement about higher cylinder temps.
biggy238 said:
I wasn't knocking his point of view, just answering questions.
My point on cylinder temps is simply this, advancing the timing is not going to burn a hole in the piston as soon as you fire the engine up and that is what I am trying to explain to Mr. Park.
But if you have an engine with advanced timing and your running the thing hard @ 1600*F for about a minute or two straight, then ya you'll melt down a piston. You can do that even without advancing timing. The point is that high EGTs and cylinder temps for long periods of time melt pistons, not from just doing a timing advancement.
Lets just end this jibberish, cuz it is getting nowhere saying the same thing and creating high cylinder temps in my head.
>You really need to read more, Matt.
How many guys on here are running 16*+ of timing and melting pistons because of the timing advancement? Ummm, I'm gonna have to say about none.
You really need to quit spinning what I say and giving me responses to what I didn't say. You don't seem to understand what I am saying. Maybe you could read and comprehend what I am saying, it would make having a conversation with you on here a whole lot easier. If you want people to think that you know what you are talking about, maybe you could talk like you know what you are talking about, and answer questions directly. How about quit the BS and we discuss relevant information in the thread.
I NEVER said that advancing timing will melt a piston. READ what I type. If I believed that, then WHY AM I RUNNING 16 degrees on MY TRUCK? I said that INCREASED TIMING should make for INCREASED AWARENESS as far as EGTs go. The WHOLE POINT of monitoring EGTs is to make sure that your combustion temps are safe. When you advance your timing, you increase cylinder temp, but decrease EGTs. What does that tell you? That you can add fuel back in after adding timing to bring your EGTs back up? No, because your combustion temps are already at the limit of where they should be.
Hot exhaust doesn't matter. We are just trying to monitor cylinder temp. As far as I'm concerned, my EGT's could be 1800, just as long as my combustion chamber temperatures are fine.
Take your truck and put the timing at 5 degrees. Your EGTs will be hotter than hell. Does that mean that you are too warm inside the cylinder? NO. It means that your timing is retarded. Now put your truck at 15 degrees. Your EGTs will drop substantially. Your combustion temps are HIGHER than they were before, but you have lower EGTs. EGT's don't matter, cyl. temp does.
If you can't think far enough into what I am saying, let me know, I will stop wasting my time explaining.
How many guys on here are running 16*+ of timing and melting pistons because of the timing advancement? Ummm, I'm gonna have to say about none.
You really need to quit spinning what I say and giving me responses to what I didn't say. You don't seem to understand what I am saying. Maybe you could read and comprehend what I am saying, it would make having a conversation with you on here a whole lot easier. If you want people to think that you know what you are talking about, maybe you could talk like you know what you are talking about, and answer questions directly. How about quit the BS and we discuss relevant information in the thread.
I NEVER said that advancing timing will melt a piston. READ what I type. If I believed that, then WHY AM I RUNNING 16 degrees on MY TRUCK? I said that INCREASED TIMING should make for INCREASED AWARENESS as far as EGTs go. The WHOLE POINT of monitoring EGTs is to make sure that your combustion temps are safe. When you advance your timing, you increase cylinder temp, but decrease EGTs. What does that tell you? That you can add fuel back in after adding timing to bring your EGTs back up? No, because your combustion temps are already at the limit of where they should be.
Hot exhaust doesn't matter. We are just trying to monitor cylinder temp. As far as I'm concerned, my EGT's could be 1800, just as long as my combustion chamber temperatures are fine.
Take your truck and put the timing at 5 degrees. Your EGTs will be hotter than hell. Does that mean that you are too warm inside the cylinder? NO. It means that your timing is retarded. Now put your truck at 15 degrees. Your EGTs will drop substantially. Your combustion temps are HIGHER than they were before, but you have lower EGTs. EGT's don't matter, cyl. temp does.
If you can't think far enough into what I am saying, let me know, I will stop wasting my time explaining.
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Easy now fellas... ... I have to say I have learned a bit from this thread but opinions are opinions and facts are facts and since no one has stated that they measured the actual combustion temp inside the cylinder. We are dealing with opinions. Right? now stating an opinion and trying to make everyone believe it are two different things. So now that we have all stated our opinions. Lets settle down. I do have to agree that EGTs are an indicator to combustion temps but can be higher or lower based on timing. Having said that it seems as though the more advanced or retarded the timing is the farther off the egts will be from it. Now has anyone been able to measure the combustion temp? If so I would be curious to see where the sweet spot is for timing on the different HP engines based on heat alone. (there are other varibles that would drive timing like low end power, noise and all that jazz) .
Sorry about the spelling
Brian
Sorry about the spelling
Brian
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