Im going to go ahead and toss out a idea here feel free to heckle.

Setting base timing on XYZ engine.... Is it possible to simply advance timing until you get knock at idle -- side note "if you can even get knock at idle no load -- " 700rpm to 1000rpm" and simply subtract a couple degrees lets say 2-3 degrees through out the entire rpm range? "coming up with some number to avoid knock at all rpm ranges not just at idle"

This is regardless of what XYZ's manual says about base timing "at idle".

an example would be XYZ engine says base timing is set at 5-8 degrees advance, where as we might add 8 degrees and idle is smoothed out immensely on a car with slightly high duration cams.

Doing this are we hurting anything? besides making the engine run a bit hotter at lower rpms and higher rpms within safe limits.

any benefit? or severe drawbacks?

Thoughts please of some educated tuners <-- I am still learning

 

No, because piston speed and rate of compression will cause knock at higher load conditions, it is impossible to run one timing figure across the engine, much the same way it is impossible to have one intake/exhaust manifold for every operating condition.

Setting your timing 2-3 off when it knocks will definitely produce a knock when you hit the gas, because cylinder load is next to 0 at idle, there for you are doing yourself a huge disservice to your engine.

Honda ecu's have a lot of timing as it is, above 44 degree's at cruise and 28-30 degree's WOT, and that is more than enough.

 

I think you misunderstood the question per say..


Im talking timing at 500-1000rpm idle conditions, if timing is 10 degrees at 700rpm where your car idles at, it wouldn't necessarily be running 10 degrees throughout the whole rpm band, just advancing timing at idle, but retard it or advance it while you start to accelerate.

basically, advancing timing while there is zero load, if there is any load on the engine my question is null and void.

Make sense?


Modified by likwidchz at 7:31 PM 7/15/2007

 

sorta, kind of an odd way to voice it, but yea, timing pulls back at WOT and is highest at cruising speeds, for good gas mileage.

 

allright, so you understand my question.. good good.


So on a slightly mild cam will it be hurting anything to run more advance? would you just be getting cleaner emissions at lower rpm at the downfall of running a couple degrees warmer?

anything else?

 

There are a lot of factors to include in timing control, compression, airflow, temperatures, fuel delivery and so forth. Adding timing will increase gas mileage because it makes power sooner, but up to a point, and Honda's have enough timing as it is. Early combustion also results in high NOX because of high combustion temps, which can be controlled by timing, or and external EGR, to cool the chamber down.

With a Honda your are almost always gonna pull some timing with a build, because the engine is flowing more air, and usually has an increase in compression. It would be better to pull a few degree's than to add to Honda's already high timing.

 

allrightys,

We were still talking about timing pre engine load correct?

 

With a "mild" cam I wouldn't see too much of a problem running 16 degrees of static timing, you could back it down to 12-14 if you really wanted to to give yourself some headroom in case things went sour.

 

well, Ill have to confess, this is'nt about a honda engine in general but just another type of car.


For instance this engine manual states that the engine should run at 6-8 degrees at idle, however screwing around with my buddys tuning software i started to poke around a tad ...myself being the uber courious one started to advance timing at the 500-1000 rpm range from the stock 6 degrees then adjusted the slider +2 then +4 going from 6 to 8 to 10 degrees advance, and I noticed the car sounded and idled much better... My buddy was convinced that i shouldn't be doing this because it was not documented on a forum of some sorts/nor the manual... the car runs 27-30 degrees of advance at cruse "any speed"

the tuning software allows you to adjust sliders at 500rpm increments and it was simply adjusted so that at 500-1000rpm it was +8 and +10 and +12 degrees over stock "stock was 6 degrees" so our total advancement was 14deg/16 deg/18 deg--- the manual said 6-8 degrees i am remembering this correctly"again this is on a stock car" this car we are working on has slightly mild cams... but nothing too crazy.


Moving on.... the sliders at 1500 were at 0 so the timing change from 1000-1500 would drop from 14 to 6 degrees of advance. In my opinion this shouldn't cause any issues at this low of rpm, the car doesn't start to make power until later due to a turbo... "However I am not a tuner Ive only read a book or 2 on engines and read quite a bit in general"

The only thing I was currently going for was exhaust noise and smoother idle.

Again the question still remains "Am I hurting this car?" or are we just trying something that not a lot of people have fiddled with?? -- saying this might be stupid or ignorant but I'm asking it anyway -- Just poking around with tuning a car.

From what I have done and fiddled with on his car it has only been good outcome so far. -- Again I am not a tuner just a very curious individual who modifies anything he gets his hands on and learns quickly.

However it is a question I needed to ask some of the honda folk because It seems too be that the people on this forum know there **** compared to any other place.


I myself am working on a 92 civic CX in the garage and putting a H22a in it and shaving the entire engine bay along with doors and handles and moldings, and roof moldings, there hasn't been a spot on this car that I haven't modified.




Modified by likwidchz at 7:22 PM 7/16/2007

 

On stock cars the ECU is assuming that base timing is correct. But you are not using a stock computer so that goes out the window.

To smooth the idle out just raise the idle speed. This is a normal "have to do" when installing cam's or a lightened flywheel on any car. I wouldn't touch the base timing unless you can remember what you set it at so you can go back to it when necessary.

I had a Civic in here running at 25degrees and spec was 12. It had terrible low end response which is not what you would want on a turbo car. Yes the timing belt was off. But if you stay within 4 degrees I would say you are going to be fine.

 

good topic for PGMFI.org

another factor... the ECU uses the distributor timing to set the injector timing. changing one changes the other.

 

Changing "base" timing by twisting the distributor is one thing, that would influence injection timing.

Changing the timing map using ECU controls is different, that wouldn't necessarily influence injection timing. Maybe injection timing has it's own map?

Shooting for incipient knock at every point in the operating envelope of the engine may not be such a good thing. You're certainly not going to achieve that very easily, even if you really feel you need to.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by likwidchz &raquo;</TD></TR><TR><TD CLASS="quote">Again the question still remains "Am I hurting this car?" or are we just trying something that not a lot of people have fiddled with?? -- saying this might be stupid or ignorant but I'm asking it anyway -- Just poking around with tuning a car.</TD></TR></TABLE>
This has the potential of hurting the car if you go too far. Depending on whether it has a knock sensor to protect itself from your experiments.

 

Well,

We would be changing timing not by physically changing anything, only computer based, so i believe it would be ignition retard/advancement.


As for going to far, I do not believe we have gone to far at this time because we are not in a high load/boosted state. if we were to advance timing 20 degrees at 6 grand and under 20 pounds of boost that would most absolutely cause some eyebrows to raise and other things to come out of the engine where there are no holes.

The knock sensor is new on this car "they usually work better plugged in"


As for the Incipient knock all the time, thats what you would do when you tune knock out -- if knock occurs retard ignition timing untill there is no knock/add fuel depending on what your AF is .... but again this area we are fiddling with is well below the area of high load...

Im taking a educated guess at this but, if the things we are doing are bad the engine should simply die at idle? does that sound about right?

 

Well, maybe you're being more careful than I thought. Or maybe not. Your first post didn't really tell me whether you're going carefully or recklessly.

Too much advance can make your engine run better for awhile. Until it burns a hole in the piston. That doesn't happen right away.

And not only that, we still don't know what kind of car you're talking about. Not all engine management is the same. OTOH, once you say what it is, some of us might just leave the discussion because of lack of SPECIFIC knowledge.

About injection timing... Injection in the port or manifold is much less sensitive to timing. This isn't a direct-injection engine, is it?

 

Carefull yes, reckless a little but not in regards to my buddy's engine.

the injectors are setup just like a Honda manifold.

Is there anyway of measuring combustion cyl temps? or would you need a EGT gauge and try and stay safe with that data?

 

Ion sensing ignition systems found on most Flex-Fuel cars are able to do this by firing a second spark into the chamber, to measure the plasma content of the chamber, which would give a good idea of total combustion efficiency, and temperature as well, I have not seen anything other than that used to measure efficiency and temps directly in the chamber.

Cylinder temperature is not an ideal thing to tune off of, it should serve only as a guide, and nothing to base your tune off of, because turbo cars net significantly higher temps due to denser air charges than NA cars. Not to mention that every head swirls fuel differently, and would net a different temperature than another car with the same setup. Even if they were identical, every engine does things slightly different from the next... There is simply no data available that says that if your exhaust is this hot, its bad. With AFR you have a chemically complete mixture of 14.7:1, which is much better to base your tune off of. (best power AFR is like 12.4:1)

Wideband O2 is good because it can actually quantify the oxygen in the exhaust more precisely, ideally a five gas analyzer in the ports would serve as the best guide, but that is not too practical.

 

heh Slowcivic2k I cant help but keep laughing at your icon, its great.


Anywho back on topic.

Is it safe to say we cant do harm at these low rpms with timing along with watching the AF from the plx display mounted in dash.

That still remains the question.

 

Well, i'm the friend. After reading his post id be sort of frustrated with the ambiguous information given.


I have a 96 DSM with DSMlink. hes trying to ask about setting idle timing higher to make the car idle smoother and sound smoother at idle.

My base timing is advanced by about 3*. The car has HKS 264/272 cams and it has a .020 bore so it idles a bit different and timing is a tad higher and is a bit rough at idle.

Through DSMlink you can change timing via sliders in 500rpm increments starting at 500 and going up to like 8k rpm. He's been messing with my timing in the 500-1000 rpm range using DSMlink to get my car to idle smoother and sound cleaner *at idle*. He's under the impression that an engine is an engine is an engine and that i should be running about the same timing at idle as honda's or any other car for that matter (this could be true and im just ignorant). So with that said he wants to know if its possible to just jack my timing sliders up to add like 10+* of timing just at idle without hurting anything (besides messing with my other things like RPM, A/F and airflowper rev.)

 

That sounds a lot safer. Somehow (maybe I'm just dense) I got the idea that he wanted to adjust the base timing. Then after reading further I thought he was wanting to adjust the spark-timing sliders all over the operating envelope. Now he's just doing that at idle and not changing the spark timing at high RPM or at high load. Right?

 

Timing would only be changed from 500 rpm to 1000 rpm thats it.

I'm not messing with it at high load
I'm not messing with it at high rpm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">That sounds a lot safer. Somehow (maybe I'm just dense) I got the idea that he wanted to adjust the base timing. Then after reading further I thought he was wanting to adjust the spark-timing sliders all over the operating envelope. Now he's just doing that at idle and not changing the spark timing at high RPM or at high load. Right?
</TD></TR></TABLE>

correct.

 

Timing would only be changed from 500 rpm to 1000 rpm thats it.

I'm not messing with it at high load
I'm not messing with it at high rpm