Maximum Timing For Stock Engine

[EverydayDiesel]

What is the maximum timing that one can run on a stock engine with full deletes and cold air intake?

Is there a general guideline in % that I should increase?

For now the head studs are the factory bolts...

[2007 5.9]

Timing is rpm and pulse related...you should be basing your timing using a calculator.
Simply setting your max at say 25 or 32* isint the right way to go about it

You may need 25* at 2600rpm but the calc may show a need for 30* at 2900rpm....

[S Phinney]

Wot at 50 percent.

[2007 5.9]

Wot at 50 percent.

If your using 50% on a re-entrant piston, your going to run the flame front out of the bowl as you start to push rpm

[arinkuddy]

Do we have re-entrant bowl then?What kind of timing would ensure the flame stays in the bowl on a stock piston? What what really happens if it gets out?

[EverydayDiesel]

On hp tuners/gassers I have an excel spreadsheet that helps me scale the values. I am looking to create similar or if some has one they want to share that would be cool too.

At the moment I am looking for a maximum % safe timing that I can run on a stock engine as a general guide for the spreadsheet

[KhakiCummins]

On hp tuners/gassers I have an excel spreadsheet that helps me scale the values. I am looking to create similar or if some has one they want to share that would be cool too.

At the moment I am looking for a maximum % safe timing that I can run on a stock engine as a general guide for the spreadsheet

EFILive has a calculator built into the Main Timing tables for Cummins.

[2007 5.9]

Do we have re-entrant bowl then?What kind of timing would ensure the flame stays in the bowl on a stock piston? What what really happens if it gets out?

6.7 engines have re-entrant bowls

[S Phinney]

If your using 50% on a re-entrant piston, your going to run the flame front out of the bowl as you start to push rpm
What are you considering when you say pushing rpm? My comment was at wot. What do you suggest then?

[EverydayDiesel]

EFILive has a calculator built into the Main Timing tables for Cummins.

It does but the original question is how much is the max % of timing i can safely apply to a stock engine

[S Phinney]

It does but the original question is how much is the max % of timing i can safely apply to a stock engine
Maximum timing is going to be relative to rpm and pulse. I am normally 45 to 50 max at say 3250 rpm and full pulse. One person already commented I am wrong. Let's see what his advice is then. I don't jniw everything for sure but have not had a single issue with that timing scenario. You are going to find very limited pointers on tuning.

[2007 5.9]

Maximum timing is going to be relative to rpm and pulse. I am normally 45 to 50 max at say 3250 rpm and full pulse. One person already commented I am wrong. Let's see what his advice is then. I don't jniw everything for sure but have not had a single issue with that timing scenario. You are going to find very limited pointers on tuning.

Perhaps you should re-read my comment.

Right/wrong was not assigned....

If you want help...its best to give specific data in which your asking help with.

Your 1/2 way there with a 3250rpm window....as "Full Pulse" isint a useful datapoint in which to enter into a calculator....

[2007 5.9]

As for the "Very Limited Pointers"...most have spent hundreds of hours, if not thousands on getting tuning right....

Simply asking what is safe, isint going to render a useful answer as the info you ask for is again retaliative to the values your specifically using in your specific application...there is no "One size fits all" when it comes to timing...

[S Phinney]

Perhaps you should re-read my comment.

Right/wrong was not assigned....

If you want help...its best to give specific data in which your asking help with.

Your 1/2 way there with a 3250rpm window....as "Full Pulse" isint a useful datapoint in which to enter into a calculator....
The op had a specific question of what is the maximum percentage of timing to safely run?

[S Phinney]

As for the "Very Limited Pointers"...most have spent hundreds of hours, if not thousands on getting tuning right....

Simply asking what is safe, isint going to render a useful answer as the info you ask for is again retaliative to the values your specifically using in your specific application...there is no "One size fits all" when it comes to timing...
One size fits all surely doesn't work. It is a varying timing percentage. The term safe is also relative to many variables.

[2007 5.9]

The op had a specific question of what is the maximum percentage of timing to safely run?


Without data like rpm and pulse...there is not a answer to give.

[2007 5.9]

Lets use this for example....most people would pick a max of say 30* of timing to run on any given "Stock" application...and lets say that person went with the standard 3200uS "Max Effort" pulsewidth, and their RPM swing was from 2600-3500rpm...this is how a 50% split would look....

RPM US ATDC BTDC
2600 3200 25 -24.92
2800 3200 27 -26.76
3000 3200 29 -28.60
3200 3200 31.5 -29.94
3500 3200 37.2 -30.00


Now running much past 30*ATDC is not going to produce any power, simply heat...which too much heat over time will infact start to erode the bowl lip and cause deformation.

So as you can see that once you get close to pushing RPM, the importance of proper timing becomes very easy to see...

Most tuners would never touch 30*ATDC in any application.

[KhakiCummins]

Lets use this for example....most people would pick a max of say 30* of timing to run on any given "Stock" application...and lets say that person went with the standard 3200uS "Max Effort" pulsewidth, and their RPM swing was from 2600-3500rpm...this is how a 50% split would look....

RPM US ATDC BTDC
2600 3200 25 -24.92
2800 3200 27 -26.76
3000 3200 29 -28.60
3200 3200 31.5 -29.94
3500 3200 37.2 -30.00


Now running much past 30*ATDC is not going to produce any power, simply heat...which too much heat over time will infact start to erode the bowl lip and cause deformation.

So as you can see that once you get close to pushing RPM, the importance of proper timing becomes very easy to see...

Most tuners would never touch 30*ATDC in any application.

Not to thread jack but Les, in the example you gave, is 3200 US just too much pulse to run above 3200 RPM because that is going to put you out of the bowl on both the leading and trailer edge? Is this the point where you would want to step up to larger injectors (assuming you have the other supporting hardware) so that you can shorten your pulse back so that you stay within that +/- 30° window?

[2007 5.9]

Not to thread jack but Les, in the example you gave, is 3200 US just too much pulse to run above 3200 RPM because that is going to put you out of the bowl on both the leading and trailer edge? Is this the point where you would want to step up to larger injectors (assuming you have the other supporting hardware) so that you can shorten your pulse back so that you stay within that +/- 30° window?


FWIW I have never and will never suggest anything over 3000uS as a safe pulse to run...in my production environment, I generally don't go over 2900uS...if i have to use that to hit a target HP, I tell the customer to buy bigger injectors.

As you can see as the RPM increases the injection window decreases...for a stock RPM truck its ok...but start getting into the 3500, 4000, 5000, and 6000rpm areas and man....the window gets VERY small.

And there is no reason to stick to 30* as a max...in fact most high performance tunes I build are in excess of 30* over xxxxRPM...

For a small reference, my personal truck...1000hp single turbo...2300uS max pulse...runs 35*@3500rpm and goes up from there..Im in the mid 40's over 4000rpm

[KhakiCummins]

Thanks for the reply Les. I know that there are a ton of variables and different situations but I was looking at it from more of a general theory perspective to better understand what some of the indicators are for a street truck as to when I should look at bigger injectors. If I ever get to that point.

[2007 5.9]

I wouldn't go over 3000uS....ever

[EverydayDiesel]

Maybe I should rephrase the question.

I have a base tune and I am looking to increase timing. How do I know when I have increased it too much?

[S Phinney]

It will get noisey and possibly excessive smoke. Timing is relative to the rpm and pulse at that moment. Have you ran what you have through the calculator to see where you are at with timing now?

[2007 5.9]

Maybe I should rephrase the question.

I have a base tune and I am looking to increase timing. How do I know when I have increased it too much?

I'll redesign my answer...

What pulse and rpm are you looking at info for?

[EverydayDiesel]

It will get noisey and possibly excessive smoke. Timing is relative to the rpm and pulse at that moment. Have you ran what you have through the calculator to see where you are at with timing now?

I just got efi live. Is there a guide on how to do this?

[S Phinney]

No there isn't really much instruction. It will take you a enormous amount of time to learn the dos and don't s. Take it slow with small adjustments on one item at a time to find the correlations between various components of the tune. There are many limiters within the tune as well. Learn how they work and what they do first.

[EverydayDiesel]

I'll redesign my answer...

What pulse and rpm are you looking at info for?

I am by bo means trying to be smart with the above comment. When I tune lsx engines I will watch the knock sensors and they will tell me when I have hit the saturation point.

How do I know when my engine has too much timing at any/ all rpms

[EverydayDiesel]

No there isn't really much instruction. It will take you a enormous amount of time to learn the dos and don't s. Take it slow with small adjustments on one item at a time to find the correlations between various components of the tune. There are many limiters within the tune as well. Learn how they work and what they do first.

Thank you for the reply. Do you have any idea on how I will know when I have hit too much timing (at any given rpm) other then noise and smoke. Is there any parms (like a knock sensor) that I can watch as an indicator?

[S Phinney]

No there isn't. You will hear the timing/injector rattle very distinctly. If you run the tune through the program calculator you can see where stock items fall. There is tremendous range in the stock tune. A performance tune won't resemble that.

[2007 5.9]

I am by bo means trying to be smart with the above comment. When I tune lsx engines I will watch the knock sensors and they will tell me when I have hit the saturation point.

How do I know when my engine has too much timing at any/ all rpms

If your using stock pulse and you begin to add timing, smoke will be a byproduct of too much timing. Remember that pilot timing is based off of main timing. So as you increase main, pilot also increases.

As for top end fueling timing, with a re-entrant piston, 50% BTDC is ok with stock pulse...start going over stock pulse, you'll need to advance your split.

If you have access to a load cell dyno..that would be your best friend.

With diesels, no knock sensors, so you have 3-potential ways to find max timing...

1. Dyno
2. Track
3. Calculated timing

[EverydayDiesel]

Thank you Les and everyone that has helped. I have been reading reading and more reading trying to figure this out.

For sure this is alot more involved then I originally intended.

http://i1056.photobucket.com/albums/t363/everydaydiesel2/FuelTimingCalculator_zps8lezitxw.png

This shows rpm vs mm3 and rpm is obvious but what exactly is a mm3? Is it fuel?

For building a street tune I understand that I want
1. Close to 0 on this chart for cruising rpm?
2. + values when accelerating under normal acceleration?


My questions are
1. why is when mm3 is at 20 and 1300 rpm then the target percentage is 28.4 but when you get to 1400 rpm then it goes to -10.2?? Why does this change from Before TDC to After TDC so dramatically with only 100rpm.
2. Why is 1000 rpm at 24mm3 so much advance compared to the values around it
3. Is this table for reference or am i suppose to edit it directly?

Any advice on what to do or how to use this table is greatly appreciated!

[EverydayDiesel]

Does anyone know?

[S Phinney]

As I suggested before run the stock tune through the calculator. You will see some 100 percent plus areas in the tuning. You will see some really low percents as well. All the areas in the tune can use some modifications. Everyone will approach this differently and is possible to get say the same peak number but have a totally different driving and running vehicle. Most won't offer much help because they had to figure out what works for their style of tuning. There isn't and completely right or wrong way to do this. There are limits to what you an or should do.

[EverydayDiesel]

Thank you for the reply. The screenshot above is the stock tune on the tuning calculator screen.

For learning purposes on my CSP5 I added
+1 to entire table for CSP5 #2
+2 to entire table for CSP5 #3
+3 to entire table for CSP5 #4
+4 to entire table for CSP5 #5

but I can tell no difference in any of the positions. I want to go more but I am a little cautious since I am already adding +4% to this table

Also you mentioned that a performance tune will be alot smoother. Should I edit the timing calculator table directly or edit the tables that it gets it calculations from?

[Move'n Up]

Your not going to be able to notice any seat of the pants difference with those small changes.

Have you ready through the links to the PDF's in the following thread
https://forum.efilive.com/showthread.php?18283-EFILive-for-Dummies-How-to-guides

Take a look at this as well
http://atptrucks.com/blog/efilive-diesel-tuning-basics/

The diesel tuning guide that Starlite Diesel sells would probably be a good investment to help you along.

[EverydayDiesel]

thank you for the reply

I bought the starlight guide and should be here any day now

what would be a reasonable amount add to that table for starters? (I assume editing the calculator table directly is what I want to do) x1.1%, x1.2% x1.3% ?

Also I am having a difficult time determining how I know when I want the values to be before TDC and when I want it at/after TDC. So far from what I can tell, I want close to 0-8* when cruising and no more then 25* when accelerating.

[Move'n Up]

Blanketing the entire table with a specific + or - % probably isn't the best approach. Yes, using the Calc table is the right way to go about it because it takes into account the tables the are ultimately responsible for determining the final number.

The numbers in your last statement are not specific enough to answer. What RPM cruise range and mm3? Also 25* in the upper RPM range under WOT is a safe target.

[EverydayDiesel]

Thanks for taking the time to explain this.

Can you tell me exactly what a mm3 is? I would think that mm3 would be a % load but why does it go to 150?

Also can you give me any indication as to what areas of the chart I should be adding values and others that I should be decreasing values as a general rule? I dont mind trying what works and what doesnt but I would like to have a general direction.

For the moment I am just looking to tune normal driving 0-2000 rpm.

[S Phinney]

Mm3 is fuel delivery. It's a reference number.

[Move'n Up]

Can you tell me exactly what a mm3 is?

19309

[arinkuddy]

mm3 is cubic millimeters of fuel. Its the volume of fuel injected. If you modify the duration table or get bigger injectors this number really isn't accurate anymore, but that doesn't really matter. You can sorta think of it as % throttle, where 0mm3 -> 0%throttle and 150mm3 -> 100%throttle. Like said before the ecm just uses it as a reference for how much fuel is getting injected.



Just for reference: 150mm3 = 0.15cc =0.03teaspoons

[EverydayDiesel]

Thanks to everyone that responded.

I guess the next steps for me are to smooth out some of the tables, log some data, and listen for rattle.

I will start by smoothing
1. main timing, base
2. fuel pressure, base
3. timing calculator table

Any other tables I should smooth out before doing some data logging?

[mpdtune]

If your using stock pulse and you begin to add timing, smoke will be a byproduct of too much timing. Remember that pilot timing is based off of main timing. So as you increase main, pilot also increases.

As for top end fueling timing, with a re-entrant piston, 50% BTDC is ok with stock pulse...start going over stock pulse, you'll need to advance your split.

If you have access to a load cell dyno..that would be your best friend.

With diesels, no knock sensors, so you have 3-potential ways to find max timing...

1. Dyno
2. Track
3. Calculated timing

4. Broken pieces of engine.

[EverydayDiesel]

Thanks everyone, I have learned alot since I created this thread originally and I got the starlite book. I still have a ton to learn.


Does this timing calculator still apply when working with a single event tune?