Advancing timing off boost?

[tom04841]

Will i see any significant spool time or off boost power by bumping up my timing off boost? My turbo doesn't hit full spool til 4200 rpms and its a little doggy until then. Just trying to pick up some of the low end power i lost when i went with the bigger turbo and web cams.

I have an eprom and ostrich, so i can tune on the fly.

Any suggestions would be greatly appreciate.

 

[DirtyBirdRacing]

First are you talking about your iginition timing or your valve timing?

The valve timing would effect your power and also your spool I would think.

In general you always want to advance your spark as much as you can to get maximum power, before knock becomes a problem.

Bill

 

[tom04841]

First are you talking about your iginition timing or your valve timing?

The valve timing would effect your power and also your spool I would think.

In general you always want to advance your spark as much as you can to get maximum power, before knock becomes a problem.

Bill

I am talking about ignition timing....sorry.

i have my WOT timing and fuel tuned.

I was just curious about off boost.....i didn't know if going too high would cause any problems. But i guess as long as i am not knocking, i am all set

 

[DirtyBirdRacing]

But i guess as long as i am not knocking, i am all set

Yeah, advance it as much as you can without knocking and you should be all set.

Bill

 

[GVR4592]

Yeah, advance it as much as you can without knocking and you should be all set.

Bill

Advancing timing past MBT won't do anything but make the car slower. Getting the engine to detonate off boost by advancing timing is going to be pretty difficult to do. Power is just going to drop off at some point.

 

[pneumo]

Are you still on stock maps? Or are you using extended maps?

If you're on stock maps look at the area around 1250 rpm to 2500 rpm and load levels 8 through 11. You'll see timing drop as rpms go up. Timing should go up as rpm goes up. Just smooth out that area by adding timing where it dips and you'll get a little more oomph.

 

[tom04841]

Are you still on stock maps? Or are you using extended maps?

If you're on stock maps look at the area around 1250 rpm to 2500 rpm and load levels 8 through 11. You'll see timing drop as rpms go up. Timing should go up as rpm goes up. Just smooth out that area by adding timing where it dips and you'll get a little more oomph.

I am running speed density with the stock timing map. Only thing is, i don't hit those boost levels in that rpm range.

 

[DirtyBirdRacing]

Advancing timing past MBT won't do anything but make the car slower. Getting the engine to detonate off boost by advancing timing is going to be pretty difficult to do. Power is just going to drop off at some point.

I did some research and I found this. MBT stands for Minimum spark for Best Torque. There is going to be a point where the power is the greatest. Less spark than that, the power falls off, more spark advance than that, you don't get any additional power.

That makes sense now, but how would you find that out for a particular engine. Would it just be through trial and error?

Bill

 

[GVR4592]

The only way to accurately do it is on a load holding dyno, some people claim to be able to do it by monitoring egt's but that's kind of risky.

 

[DirtyBirdRacing]

The only way to accurately do it is on a load holding dyno, some people claim to be able to do it by monitoring egt's but that's kind of risky.

So, in that respect it is kind of like adjusting valve timing. To accuratly adjust valve timing for maximum power you always have to do it on a dyno correct?

Also, aren't load holding dyno's pretty rare or no?

Bill

 

[GVR4592]

It's not really the same as adjusting valve timing. Changing valve timing is going to affect the whole curve. If you are tuning cell by cell on a load holding dyno, you are affecting the individual cell you are tuning. Using the dyno to hold rpms and load at a specific point, you would then advance/retard ignition timing in that rpm and load range until the engine made the maximum amount of torque.

 

[DirtyBirdRacing]

Ok, I understand now thanks for answering my questions. So this load holding dyno method could take the place of jsut making logs going up and down my street and adjusting it based on knock and o2 sensor voltage? Sorry if that sounds like a stupid question, just want to make completely sure.

Bill

 

[tkelly27]

It not only takes the place of, it's the only way to accurately reproduce and log conditions. There are so many variables from one pass on the street to the next. The next best place to log and tune is the drag strip/race track. The worst place is the street. It's extremely hard to get accurate and repeatable runs on the street, and the tools used to get performance data are not as well calibrated as a dyno or a drag strip.

I think most good tuner shops should have eddy current or water brake dynos that can hold you at a specific RPM range.

You advance the spark to ensure that as much of the charge as possible is burnt while the piston is traveling down during the power stroke. If it's not advanced enough, you'll still have charge burning at BDC of the power stroke. However, to far advanced, and you'll have the burning gas charge working against compression stroke of the engine, turning usable work into counter productive work. This also leads to detonation because the pressures involved spike. Did I get that right?

If you don't have a dyno, a really good way is to go to the track and dial it in until you start going slower, then dial it back

To the OP, one thing I've heard about working is to pull a small amount of fuel and get your EGT's up under non-boosted conditions. More EGT = more energy in the exhaust = quicker spool up.

Are you running DSMap? How do you like it?

 

[tom04841]

I am using DSMap, and I love it.

I have also heard that pulling timing will create higher egt's and spool quicker too. At the same time, i heard this method can also lead to melted pistons.