for You Guys Concerned About Lag

1421 Views 20 Replies 7 Participants Last post by mrE, Sep 7, 2007

drewgo

Discussion Starter · Sep 4, 2007 (Edited)

I had a conversation with Tissimo asking about timing and its purpose. After that I started to research and this is what I found. Thought I could share with you guys

The stock 1jz ECU has a very conservative timing map.
Follow me in this senerio:
Stock Twins, 1st gear
@ 1500rpm you feel the twins start to spool timing is aggressive to get them going
@2500rpm twin are @ full spool & ECU pull a bit of timing to smoot out power curve
3000-4000 rpm still full spool but ECU starts to add timing to hold up the power curve to about 5500
@ 5800-6200 Still full spool but twins can't supply enough air to keep up with the powerband
@6500 ECU has reached its peak in timing and can't add more timing otherwise it will start to get knock
6500-7200(redline) powerband steadily drops off ( in many cases it starts to drop off by 5800rpm)

NOW, SAME CAR BUT NOW IT'S SINGLE TURBO (GT4082,.68 A/R) STOCK ECU & SAFC.
@1500 car is bit peppy due to timing being somewhat aggressive to spool the twins, but there are non
@2800 I hear the single spooling but no power response is felt. The reason, the ECU's timing map is set to pull timing at this range because that's were the twins would be at full spool.
@3000-4000rpm, GT40 is screaming but still in lag mode, timing is absent therefore not enough psi from the single to create any powerband.
@4000-4200rpm, this is were the ECU adds timing to keep the powerband for the twins, therefore giving the GT40 the timing that it needs to spool and create some good power.
4200-7200rpm, seems like the timing is about leveled and relys on the knock sensor to pull timing if need be.

In Conclusion: The remedy to lag on a 1jz is mainly adjusting the timing to be in accordance with the turbo's characteristics. Your backhousing has something to do with it aswell. You can use an upgraded ECU (i.e. Mines, Blits, SARD,etc...) which normally has a more aggressive timing map that will assist in spooling a single turbo or a piggy-back such as an emanage blue or ultimate that will allow you to change the timing curve.

Here is my dyno sheet. If someone has a stock twin dyno sheet to compare, would help clarify my findings. Add or comment on this as you wish we can all benefit from this info and whoever else can add to this.

See less See more

1 - 20 of 21 Posts

chris davey

· #2 · Sep 5, 2007

I think the point you are forgetting is that the stock ecu uses more than just rpm inputs to determine fuelling and ignition timing. Obviously, the other huge factor is the MAP sensor.

E.g. where you say the ignition timing ramps up as the turbos come on boost at 3000rpm, it would be doing this because it is at X on rpm scale and Y on MAP scale. When you install your larger turbo you will still be at X on rpm, but Y -5psi on the MAP scale.

Also, I am not sure where you are getting this info. from but from all reports timing is at its lowest (most retarded) at peak torque which would be around 4500-5000 on a stock twins 1jz.

Everyone knows what the answer is. Aftermarket ecu

Can do a lot more fiddling to get it all right there.

BTW why do you say that the ecu ups timing enough at 4000rpm to get the gt40 spooling? I think you will find that the major contributing factor to that is the physical size of a t4 exhaust housing compared to ct12a's. (even with .68 a/r)

I have a fair few timing maps of different 1jz turbo combinations but the biggest is a GT35 .8 a/r so can't compare directly.

See less See more

drewgo

Discussion Starter · #3 · Sep 5, 2007

chris davey said:
I think the point you are forgetting is that the stock ecu uses more than just rpm inputs to determine fuelling and ignition timing. Obviously, the other huge factor is the MAP sensor.

E.g. where you say the ignition timing ramps up as the turbos come on boost at 3000rpm, it would be doing this because it is at X on rpm scale and Y on MAP scale. When you install your larger turbo you will still be at X on rpm, but Y -5psi on the MAP scale.

Also, I am not sure where you are getting this info. from but from all reports timing is at its lowest (most retarded) at peak torque which would be around 4500-5000 on a stock twins 1jz.

Everyone knows what the answer is. Aftermarket ecu Can do a lot more fiddling to get it all right there.

BTW why do you say that the ecu ups timing enough at 4000rpm to get the gt40 spooling? I think you will find that the major contributing factor to that is the physical size of a t4 exhaust housing compared to ct12a's. (even with .68 a/r)

I have a fair few timing maps of different 1jz turbo combinations but the biggest is a GT35 .8 a/r so can't compare directly.

At 4500 rpm the stock ecu has to play with timing to keep the twins spooling and powerband up. Peak TQ on the twins is not 4500-5000, it's at 3000-4000. Just look at any stock dyno sheet. Hence,The reason why the timing is retarded at that range and also the reason why a single has a hard timer spooling.

Cosmo

· #4 · Sep 5, 2007

Are you watching the timming some how to determin this? Lets see some datalogs to back up your assumptions. Why would the twins stop spooling???

"At 4500 rpm the stock ecu has to play with timing to keep the twins spooling"

This is just not right.

The stock timming map is most likley 2D, with RPM for X, and Pressure for Y exactly like Davey is saying. Then there is a seperate table for knock to reduce the total timming based on the count it sees.

drewgo

Discussion Starter · #5 · Sep 5, 2007

What's not right? That the ECU adjust timing to keep the powerband up after 4500rpm! What's not right about that.
Also I never said "stop spooling" , read before you take it out of context.

my87tbo

· #6 · Sep 5, 2007

I can see some of the points being made here but don't forget what roll the valvetrain and exhaust system plays in these equations.

chris davey

· #7 · Sep 5, 2007

As I see it, you are making assumptions. You can ASS-U-ME all you want but in the end if there is no hard data to back it up then it isn't going to convince anyway.

I will conceid the point on peak torque for stock twins. (I have been single and microteched for a long time now

) Yes, 4000rpm seems about right.

At 4500 rpm the stock ecu has to play with timing to keep the twins spooling and powerband up.

Please define "play with"?

Peak TQ on the twins is not 4500-5000, it's at 3000-4000. Just look at any stock dyno sheet. Hence,The reason why the timing is retarded at that range and also the reason why a single has a hard timer spooling.

That would be true if the ecu only worked out timing via rpm but as I said, it also takes into account boost. So at 3500rpm, you are saying that it is at peak torque and hence most retarded timing (well that is what it would be like if it was tuned for max power and remember the fuelling side of things so that is obviously not the case, so this is an assumption) and the turbos could be making anywhere from 12psi to 15psi or so depending on the flow capabilities of the rest of the system.

Now a single turbo setup like yours is certainly not going to be making 12-15psi at 3500rpm. Maybe 5psi? Either way, it is going to be less and therefore if it is tuned like any sane person would there would be more ignition advance at [email protected] than [email protected]

You get what I am saying?

BTW what boost was your dyno run at?

See less See more

drewgo

Discussion Starter · #8 · Sep 5, 2007 (Edited)

chris davey said:
As I see it, you are making assumptions. You can ASS-U-ME all you want but in the end if there is no hard data to back it up then it isn't going to convince anyway.

I will conceid the point on peak torque for stock twins. (I have been single and microteched for a long time now ) Yes, 4000rpm seems about right.

Please define "play with"?

That would be true if the ecu only worked out timing via rpm but as I said, it also takes into account boost. So at 3500rpm, you are saying that it is at peak torque and hence most retarded timing (well that is what it would be like if it was tuned for max power and remember the fuelling side of things so that is obviously not the case, so this is an assumption) and the turbos could be making anywhere from 12psi to 15psi or so depending on the flow capabilities of the rest of the system.

Now a single turbo setup like yours is certainly not going to be making 12-15psi at 3500rpm. Maybe 5psi? Either way, it is going to be less and therefore if it is tuned like any sane person would there would be more ignition advance at [email protected] than [email protected]

You get what I am saying?

BTW what boost was your dyno run at?

Chris, there is no hard data to back up your theory. So what is your point?
I agree that the ECU takes into account Fuel, RPM, boost, and not to mention other variables like Tempurature, throttle position.... etc. You can discredit all you want by saying it's my assumption.
But answer me this.... In my case I hit full boost (20psi)between 4200 & 4600rpm on my stock ECU. If I tune the timing map would or would not my turbo have less lag?

mig240sx

· #9 · Sep 6, 2007

Interesting... :drama: ...got my popcorn.

chris davey

· #10 · Sep 6, 2007

I like to see numbers basically and AFAIK it can't happen.

@3000-4000rpm, GT40 is screaming but still in lag mode, timing is absent therefore not enough psi from the single to create any powerband.
@4000-4200rpm, this is were the ECU adds timing to keep the powerband for the twins, therefore giving the GT40 the timing that it needs to spool and create some good power.

But answer me this.... In my case I hit full boost (20psi)between 4200 & 4600rpm on my stock ECU. If I tune the timing map would or would not my turbo have less lag?

I assume when you say "tune" your timing map you mean advance the timing further at 3000-4200 as per your first post? If that is the case, then yes I think you "could" lower your boost threshold if you did this. I am not certain though so give it a go

(reason being as you said, all this is assumptions so we don't really know what the starting point is)

I have my timing numbers (at home on spreadsheet) and spool characteristics but I am not going to change them all just to check.

Get an emanage or whatever and slap some more in down low & see what happens.

The other side of the equation is the principles of an antilag system. Being that if you retard the timing then the exhaust gasses will be more powerful & aid spoolup. Could timing be too advanced? (I don't think so but it is a possibility)

See less See more

chevyeater-on-sf

· #11 · Sep 6, 2007

You may want to clear up that spot where the A:F goes in the shitter (right as the turbo is spooling) before building a whole timing project.

In my tuning experience, less timing provides more boost at lower RPMs but, more timing gets the engine into its powerband in less time.

drewgo

Discussion Starter · #12 · Sep 6, 2007

chris davey said:
I assume when you say "tune" your timing map you mean advance the timing further at 3000-4200 as per your first post? If that is the case, then yes I think you "could" lower your boost threshold if you did this.

That's all you needed to say, no need to get so elaborate about the whole physics of things.
Your assumptions and my assumption are in agreement that advancing your timing in that range will get your turbo to spool much faster.

chevyeater-on-sf said:
You may want to clear up that spot where the A:F goes in the shitter (right as the turbo is spooling) before building a whole timing project.

In my tuning experience, less timing provides more boost at lower RPMs but, more timing gets the engine into its powerband in less time.

I think you have it backwards.
Advance timing, meaning spark with the piston closer to the top of the cylinder, which burns more fuel mixer, thus producing more exhaust to spool a turbo. Also increasing your EGT's if advanced too much.
Retard Timing, means spark is delayed allowing the piston to move down some before mixer is ignited. Less fuel will ignited mean less exhaust gases which in turn more lag. EGT's will drop when this takes place.

mrE

· #13 · Sep 6, 2007

drewgo said:
I think you have it backwards.
Advance timing, meaning spark with the piston closer to the top of the cylinder, which burns more fuel mixer, thus producing more exhaust to spool a turbo. Also increasing your EGT's if advanced too much.
Retard Timing, means spark is delayed allowing the piston to move down some before mixer is ignited. Less fuel will ignited mean less exhaust gases which in turn more lag. EGT's will drop when this takes place.

You can stop thinking now and rely on the actual facts a little more.
What does an ignition event signify to begin with? Why would advancing timing generate a larger volume of exhaust gas over the exhaust stroke?
Lets go back to the fundamentals for a second and realize that spark timing actually controls how much of the combustion event (aka 'controlled burn of air fuel mixture') is used to generate torque on the piston face, and how much of it is allowed to flow out of the exhaust valves. Retard the spark and you send more of the 'pressure wave' towards the turbine. Advance the spark - and up to a point, you make more torque. The 'but' in this situation is the fact that less of the hot and expanded exhaust gas is diverted to the turbo. Too much advance will ignite the mixture too early and cause the piston to fight the pressure wave a.k.a. EXPLOSION on its way up during the compression stroke. The engine makes less torque, makes less boost a lot slower and the cylinder walls, landings, valves etc are subjected to greater temperatures and pressures for no good reason. All this commotion still won't spool up the turbo any faster, regardless of how many letters you write to the boost fairy.

Less advance increases EGT's which is why most engines run timing retard and fuel enrichment combined on coldstarts to bring the catalytic converter/s to operational temperature as soon as possible. Less advance does however reduce cylinder teperatures, the two aren't the same thing.

In my experience, the fastest way to spool a large turbo is a leaner mixture and a few degrees less advance than required at max torque for the given map vs rpm input. That is, until you reach the compressors efficiency range (which can be calculated from a compressor map or aproximated based on fueling requirements). The aim is to keep the volume of exhaust gas making its way to the turbine high and hot, whilst sacrificing as little engine torque as possible. Toyota has the right idea to begin with; stoich until 4psi then progressively richer as boost rises. The reason a large turbo runs richer thank stockies coming online includes the fact that the compressor pressure ratio vs flow rate per lb has the outputted charge in an inefficiency zone.

I don't know if its obvious yet but engine tuning is a science, not a game controlled by a rotary knob and a flashing blue screen as some people seem to think.

See less See more

drewgo

Discussion Starter · #14 · Sep 6, 2007

mrE said:
I don't know if its obvious yet but engine tuning is a science, not a game controlled by a rotary knob and a flashing blue screen as some people seem to think.

I am sorry my friend, you are getting too complicated here and what you are saying make no sense or maybe to you.

I agree with It being a science but it's not rocket science. The facts are that a properly tuned timing Map will allow you to spool much faster. And advancing the timing is the need to get it going then it'll retard as needed, So why are you going into great length explaining something that is simple yet make it sound so complicated.

This is turning into a "look how much I know" piss party... Keep it simple

mig240sx

· #15 · Sep 6, 2007

:drama: Popping microwave popcorn without burning a single corn is also a science, it's complicated stuff! The microwave has to be tuned just right and the timing has to be perfect!

mrE

· #16 · Sep 7, 2007

drewgo said:
I agree with It being a science but it's not rocket science. The facts are that a properly tuned timing Map will allow you to spool much faster. And advancing the timing is the need to get it going then it'll retard as needed, So why are you going into great length explaining something that is simple yet make it sound so complicated.

Because you clearly have no idea and saying its 'simple' proves it.

drewgo said:
I am sorry my friend, you are getting too complicated here and what you are saying make no sense or maybe to you.
This is turning into a "look how much I know" piss party... Keep it simple

Go and get your timing map 'properly tuned' with the SAFC, see how much faster it spools up on the street.

What can anyone say to someone so far up their own ass they actually believe such nonsense. You're so convinced what you're saying is correct, in reality any assumptions you make are based on a fantasy fairytale in that empty head of yours. Its obvious your understanding of management ends at the mere concept of an airflow altering device so really, who's having the piss party? I'm surprised your keyboard still works.

Put the popcorn away, let the self proclaimed tuner here do his life's work and get us all 'spooling up much faster', i can't wait to see what else you have in store for us big man.

mig240sx said:
:drama: Popping microwave popcorn without burning a single corn is also a science, it's complicated stuff! The microwave has to be tuned just right and the timing has to be perfect!

If engineers didn't 'tune' the microwave ovens magnetron you'd be cooking popcorn on a stove.

Yes, keep laughing.

See less See more

drewgo

Discussion Starter · #17 · Sep 7, 2007

mrE said:
Go and get your timing map 'properly tuned' with the SAFC, see how much faster it spools up on the street.

What can anyone say to someone so far up their own ass they actually believe such nonsense. You're so convinced what you're saying is correct, in reality any assumptions you make are based on a fantasy fairytale in that empty head of yours. Its obvious your understanding of management ends at the mere concept of an airflow altering device so really, who's having the piss party? I'm surprised your keyboard still works.

Damn dude, if you are getting so revved up because of this discussion... you seriously need to get laid, Hopefully that will help you cool down some.

Here's another pointer for you, SAFC... does not tune timing. Go grab a book and read.

No one is self proclaimed here Timmy, we all learn through trial and error. As I am sure you have too. So take deep breath and go play in traffic.

BTW: Get your post count up if you wanna come pretending to be "all knowing"
2 post just does not cut it here.

chevyeater-on-sf

· #18 · Sep 7, 2007

drewgo said:
I think you have it backwards.
Advance timing, meaning spark with the piston closer to the top of the cylinder, which burns more fuel mixer, thus producing more exhaust to spool a turbo. Also increasing your EGT's if advanced too much.
Retard Timing, means spark is delayed allowing the piston to move down some before mixer is ignited. Less fuel will ignited mean less exhaust gases which in turn more lag. EGT's will drop when this takes place.

No, you have it backwards. Less timing equals higher EGTs because the mixture is burning closer to the exhaust valve opening event. The fuel injected still burns, just more in the exhaust than in the combustion chamber, resulting in a kind of junior anti-lag starter kit effect. The turbo spools sooner but there is no power to go with it since it is all burning up in the manifold instead of pushing the pistons down. That is what mrE tried to explain to you also...

This isn't what I read in some book or sat around picking my nose figuring on, this is what actually happens when I adjust the timing on a car and datalog the results.

Now that we have that settled, your problem with spoolup is the A:F dipping into the 9s on spool. That kills spool time like nothing else. Get it to taper from 13s at the start of spool down to 11s when it is done, nice and linear and it will make a huge difference in the spoolup time (not RPM) of your car. After that, you can play with the timing and see what it does to spool and see what it does for yourself. Maybe you can come back here and post up your finding on that for us...

See less See more

mig240sx

· #19 · Sep 7, 2007

mrE said:
If engineers didn't 'tune' the microwave ovens magnetron you'd be cooking popcorn on a stove.

Yes, keep laughing.

Hey, I'm just the popcorn guy, enjoying the "piss party" show.

drewgo

Discussion Starter · #20 · Sep 7, 2007 (Edited)

chevyeater-on-sf said:
No, you have it backwards. Less timing equals higher EGTs because the mixture is burning closer to the exhaust valve opening event. The fuel injected still burns, just more in the exhaust than in the combustion chamber, resulting in a kind of junior anti-lag starter kit effect. The turbo spools sooner but there is no power to go with it since it is all burning up in the manifold instead of pushing the pistons down. That is what mrE tried to explain to you also...

This isn't what I read in some book or sat around picking my nose figuring on, this is what actually happens when I adjust the timing on a car and datalog the results.

Now that we have that settled, your problem with spoolup is the A:F dipping into the 9s on spool. That kills spool time like nothing else. Get it to taper from 13s at the start of spool down to 11s when it is done, nice and linear and it will make a huge difference in the spoolup time (not RPM) of your car. After that, you can play with the timing and see what it does to spool and see what it does for yourself. Maybe you can come back here and post up your finding on that for us...

Thank you...
Make sense what you are saying, and I believe what you are explaining. I've had multiple conversations with 2 well know tuners here in south Florida regarding this theory they said almost the same thing you just mentioned. The part where the turbo is starting to spool yet goes nowhere is in my case 3000-4000 range. Keep in mind that my turbo is spooling around 2800rpm. In 3rd it's start even sooner 2500 or so. I can be anywhere around 4 psi. If the ecu allowed more timing in can make use of the spool that is already there and set off the chain reaction that will allow the powerband to come in sooner. I am wrong in saying that?
After market ECU's do a decent job on spooling a single better in the 3k range because of advance timing there, which is what i am looking for and for more rpm's up top. That is not me making up stories or my own assumptions of this.
Mine's , blitz, sard, stealth and so on, all have more advance timing there. They know why they do it. That's all, I've been churning on this for some time and know that with the stock ECU, single turbo 1j are experiencing more lag.

The car is getting a ECU Upgrade and a retune. We'll be making that dip very linear and at the 7k it goes high so that will be correct too. I am hoping in 2 weeks if time permits I'll be retuning, But I have to make some time to remove the BCC & SCC. If don't see any improvement in faster spool I just spent the past 2 days making a fool of myself.

See less See more

1 - 20 of 21 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.