Discussion: Increasing Spool Up : AFR, Timing, MIVEC
Jun 17, 2010, 07:24 AM
#1
Discussion: Increasing Spool Up : AFR, Timing, MIVEC
Since there is no point to reinvent the wheel... Let's discuss ways to increase spool up on the EVO X. I did not come across a thread yet that discusses all different parameters.
The 10th generation Evolution is different from the past DSM 1G & 2G, EVO VII-IX 4G6x motors... thus a discussion pertaining to this car would be ideal. Considering there is a brand new 4b11 engine...
Parameters involved in turbo spool:
Air fuel Ratio (AFR): Lean vs. Rich
Fuel: 91, 93, E85, Race Fuel
MIVEC: Intake & Exhaust Timing
Boost Solenoid Settings: Duty Cycle %
Ignition Timing: Increase vs. Retard Timing
Closed/Open Loop Tables: Higher vs. Lower load to initiate Open Loop
Gearing: Short vs Long Gears
2008 vs 2010 ECU: 08 LEAN SPOOL OFF vs. 10 LEAN SPOOL ON
Now let's discuss...
Let's start with boost solenoids, to maximize spool up you want the boost solenoids to be at 100% DTC between 1000rpm til 2500rpm minimum. You can go beyond 2500rpm @ 100% depending on turbo STOCK vs. Aftermarket.
Now gearing... lower gears i.e. 1st gear produces less load than 3rd gear. Thus the turbo will spool faster in higher gears 3rd, 4th, 5th, 6th(MR). Thus most people tune in either 4th or 3rd gear, some tuners use 5th gear only using a dyno and not road tuning.
The 08 GSR/MR has LEAN SPOOL OFF. This means you can adjust the AFR's you want much better, especially using exotic fuels. All this means you have better control over your fuel. The people with the 2010 GSR/MR have LEAN SPOOL ON... means the ECU will not let you richen your spool area. However, this can be disabled to gain greater control over your spool up fueling. Critical when using E85.
Fuels: There is a great debate between E85 and Gasoline which spools better. But here is a caveat... E85 requires a richer mixture during spool up 12's-13's (sometimes lower). This is because E85 has 39% less potential energy than gasoline. Fuels are a section that need to be discussed during spool up...
MIVEC: Typically, to achieve a fast spool up advance the intake cam and retard the exhaust cam during spool up. For example +35 intake and -10 retard during spool up. The amount you can advance and retard depends on TURBO design as well as Camshafts OEM vs. Aftermarket. Typically you can advance and retard the stock cam more than you can a aftermarket cam... Also with cams you typically move you dyno plot to the right. Gain mid range and upper rpm power. On a turbo that has built in anti-surge i.e. FP Green/Red. You are able to advance and retard the cams more than you would be able to do on a non-anti-surge turbo i.e. OEM/STOCK, DOM II, etc...
AFR & Timing... this is where the discussion really will start a debate...
What is better for spool up?
Advanced Timing and Leaner AFR vs Retard Timing and Rich AFR
In the old DSM days... retarding the timing and adding fuel provided a quicker spool. The downside, the driveability would become worse. The power coming on would feel much stronger, "Feel" the boost kick in.
The reasoning is very similar to that of a standalone ECU anti-lag system / Bang-Bang system. You retard the timing and add fuel. The effect that is produces since not all of the fuel burns in the combustion chamber it is discharged into the exhaust manifold where the remaining fuel ignites and springs the turbine in the turbo. Producing a faster spool. Since in the combustion process, a spark ignites the fuel and then the burn spread outward. The fuel at the outer edges of the combustion process never ignites and then is shoot to the exhaust manifold to ignite.
Very nice explanation...
Now let's consider that the 4B11 has a aluminum block & head... along with a modern cooling system. So therefore it is able to dissipate heat much faster than a iron block. Would this theory of tuning still hold true?
Will adding more fuel and retarding the timing spool much faster?
OR
Will adding less fuel and advancing the timing spool faster on the EVO X? Creating more heat to spool the turbo...
Closed vs. Open Loop Tables: This will directly correlate to what was discussed above. Which is more beneficial during spool up running a leaner vs. richer AFR...
DISCUSS...
The 10th generation Evolution is different from the past DSM 1G & 2G, EVO VII-IX 4G6x motors... thus a discussion pertaining to this car would be ideal. Considering there is a brand new 4b11 engine...
Parameters involved in turbo spool:
Air fuel Ratio (AFR): Lean vs. Rich
Fuel: 91, 93, E85, Race Fuel
MIVEC: Intake & Exhaust Timing
Boost Solenoid Settings: Duty Cycle %
Ignition Timing: Increase vs. Retard Timing
Closed/Open Loop Tables: Higher vs. Lower load to initiate Open Loop
Gearing: Short vs Long Gears
2008 vs 2010 ECU: 08 LEAN SPOOL OFF vs. 10 LEAN SPOOL ON
Now let's discuss...
Let's start with boost solenoids, to maximize spool up you want the boost solenoids to be at 100% DTC between 1000rpm til 2500rpm minimum. You can go beyond 2500rpm @ 100% depending on turbo STOCK vs. Aftermarket.
Now gearing... lower gears i.e. 1st gear produces less load than 3rd gear. Thus the turbo will spool faster in higher gears 3rd, 4th, 5th, 6th(MR). Thus most people tune in either 4th or 3rd gear, some tuners use 5th gear only using a dyno and not road tuning.
The 08 GSR/MR has LEAN SPOOL OFF. This means you can adjust the AFR's you want much better, especially using exotic fuels. All this means you have better control over your fuel. The people with the 2010 GSR/MR have LEAN SPOOL ON... means the ECU will not let you richen your spool area. However, this can be disabled to gain greater control over your spool up fueling. Critical when using E85.
Fuels: There is a great debate between E85 and Gasoline which spools better. But here is a caveat... E85 requires a richer mixture during spool up 12's-13's (sometimes lower). This is because E85 has 39% less potential energy than gasoline. Fuels are a section that need to be discussed during spool up...
MIVEC: Typically, to achieve a fast spool up advance the intake cam and retard the exhaust cam during spool up. For example +35 intake and -10 retard during spool up. The amount you can advance and retard depends on TURBO design as well as Camshafts OEM vs. Aftermarket. Typically you can advance and retard the stock cam more than you can a aftermarket cam... Also with cams you typically move you dyno plot to the right. Gain mid range and upper rpm power. On a turbo that has built in anti-surge i.e. FP Green/Red. You are able to advance and retard the cams more than you would be able to do on a non-anti-surge turbo i.e. OEM/STOCK, DOM II, etc...
AFR & Timing... this is where the discussion really will start a debate...
What is better for spool up?
Advanced Timing and Leaner AFR vs Retard Timing and Rich AFR
In the old DSM days... retarding the timing and adding fuel provided a quicker spool. The downside, the driveability would become worse. The power coming on would feel much stronger, "Feel" the boost kick in.
The reasoning is very similar to that of a standalone ECU anti-lag system / Bang-Bang system. You retard the timing and add fuel. The effect that is produces since not all of the fuel burns in the combustion chamber it is discharged into the exhaust manifold where the remaining fuel ignites and springs the turbine in the turbo. Producing a faster spool. Since in the combustion process, a spark ignites the fuel and then the burn spread outward. The fuel at the outer edges of the combustion process never ignites and then is shoot to the exhaust manifold to ignite.
Very nice explanation...
When timing is advanced the spark ignites the air/fuel mixture at a sooner point. This gives the mixture more time to burn in the cylinder. Most of the heat from this will be absorbed by the engine itself. The reason this makes more power is because the mixture has a longer time to burn before the piston reaches tdc. Since it has more time to burn it is going to make the pressure pushing down greater. This is where the exrta power comes from. More pressure downwards when the piston is at tdc. This is also why advancing timing can create knock or pre-ignition.
Retarding the timing makes the mixture start to burn closer to tdc. This will make less power since the mixture has less time to expand before the piston reaches tdc. Retarding will cause some of the mixture to be burning when the piston is moving down and when moving up on the exhaust stroke. Since the mixture burns later the heat has less time to be absorbed by the engine and as a result it will go into the exhaust manifold which will help spool the turbo. The mixture burning during the exhaust stroke also causes the turbo to spool sooner since the mixture is burning with the exhaust valves open. This is how antilag works, it retards timing so the mixture is burning when the exhaust valve is open.
When you add the fuel, the mixture will be burning longer since there is more fuel to burn. This will also cause the mixture to burn when the exhaust valves are open which makes the turbo spool faster. When the spark plug first goes off all the fuel doesn't burn right away. The fire spreads outward away from the spark plug. Since the flame spreads outward it takes time for all the fuel to burn. So, if you add fuel there is more fuel to burn which equals more time it takes to burn all of it. That translates into some of the fuel burning when the exhaust valves are open. This is another way of knowing how adding the fuel help.
Retarding the timing by itself will make the turbo spool faster. Adding fuel in addition to retarding the timing will make the turbo spool even faster. Adding fuel without retarding the timing isn't going to do anything for spool.
A leaner mixture might make the turbo spool a little faster. But, the way I described is the best way to get better spool. With the leaner mixture a lot of the extra heat that is generated is going to be absorbed by the block and then the cooling system will take the heat from the block. So, some of the heat will go to the exhaust manifold and help spool but the majority of it will go into the block. This is also why the leaner mixture increases the chance of knock. The block gets hot and heat creates knock. The heat from the block will be drawn away by the coolant system and the fuel in the cylinder. If too much heat is transferred to the fuel then you will either knock or get pre-ignition.
Retarding the timing makes the mixture start to burn closer to tdc. This will make less power since the mixture has less time to expand before the piston reaches tdc. Retarding will cause some of the mixture to be burning when the piston is moving down and when moving up on the exhaust stroke. Since the mixture burns later the heat has less time to be absorbed by the engine and as a result it will go into the exhaust manifold which will help spool the turbo. The mixture burning during the exhaust stroke also causes the turbo to spool sooner since the mixture is burning with the exhaust valves open. This is how antilag works, it retards timing so the mixture is burning when the exhaust valve is open.
When you add the fuel, the mixture will be burning longer since there is more fuel to burn. This will also cause the mixture to burn when the exhaust valves are open which makes the turbo spool faster. When the spark plug first goes off all the fuel doesn't burn right away. The fire spreads outward away from the spark plug. Since the flame spreads outward it takes time for all the fuel to burn. So, if you add fuel there is more fuel to burn which equals more time it takes to burn all of it. That translates into some of the fuel burning when the exhaust valves are open. This is another way of knowing how adding the fuel help.
Retarding the timing by itself will make the turbo spool faster. Adding fuel in addition to retarding the timing will make the turbo spool even faster. Adding fuel without retarding the timing isn't going to do anything for spool.
A leaner mixture might make the turbo spool a little faster. But, the way I described is the best way to get better spool. With the leaner mixture a lot of the extra heat that is generated is going to be absorbed by the block and then the cooling system will take the heat from the block. So, some of the heat will go to the exhaust manifold and help spool but the majority of it will go into the block. This is also why the leaner mixture increases the chance of knock. The block gets hot and heat creates knock. The heat from the block will be drawn away by the coolant system and the fuel in the cylinder. If too much heat is transferred to the fuel then you will either knock or get pre-ignition.
Will adding more fuel and retarding the timing spool much faster?
OR
Will adding less fuel and advancing the timing spool faster on the EVO X? Creating more heat to spool the turbo...
Closed vs. Open Loop Tables: This will directly correlate to what was discussed above. Which is more beneficial during spool up running a leaner vs. richer AFR...
DISCUSS...
Jun 18, 2010, 12:12 PM
#2
So after more research I am finding... if I just change timing and keep everything the same. Keep fuel the same, keep the rest of the map identical except timing. That increasing timing produces a much sharper boost curve meaning, it increases spool dramatically.
These results are on a FP Green of course. If anyone would want to test it on the stock turbo and post results that would be great.
Not only that but it also creates a nice boost spike... so adjusting the solenoids will be critical. Gain about 2-3 psi increasing just timing during spool up, not during peak boost.
Very interesting... dumping fuel and retarding the timing gave a very sluggish spool and lower peak boost.
I will keep testing over the next few days...
These results are on a FP Green of course. If anyone would want to test it on the stock turbo and post results that would be great.
Not only that but it also creates a nice boost spike... so adjusting the solenoids will be critical. Gain about 2-3 psi increasing just timing during spool up, not during peak boost.
Very interesting... dumping fuel and retarding the timing gave a very sluggish spool and lower peak boost.
I will keep testing over the next few days...
Jun 22, 2010, 12:38 PM
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subscribed! interesting findings clipse. can't wait to see what tephra has to say. Thanks for giving me something to look forward to reading while i'm at work 
now clipse, did you notice a difference in your afr's when you increased just timing in the spool up area? i'm just wondering if it went leaner, which if it did. i wonder if taking fuel out would make it spool even faster?
now clipse, did you notice a difference in your afr's when you increased just timing in the spool up area? i'm just wondering if it went leaner, which if it did. i wonder if taking fuel out would make it spool even faster?
Jun 22, 2010, 03:32 PM
#7
subscribed! interesting findings clipse. can't wait to see what tephra has to say. Thanks for giving me something to look forward to reading while i'm at work
now clipse, did you notice a difference in your afr's when you increased just timing in the spool up area? i'm just wondering if it went leaner, which if it did. i wonder if taking fuel out would make it spool even faster?
now clipse, did you notice a difference in your afr's when you increased just timing in the spool up area? i'm just wondering if it went leaner, which if it did. i wonder if taking fuel out would make it spool even faster?
The stock injector calibration table actually forces the injectors to inject less fuel in the spool up area, one of the reasons why even with adding fuel there it still is a bit lean. I adjusted those pulse width areas to be 0 for more linear fuel control. It also made my spool richer and made me lose spool time. So now adjust the fuel map to make it leaner to gain spool again.
But if you use the stock injector calibration map. Then just adding timing will produce leaner spool, much quicker spool. I keep adding timing and taking away fuel for testing. Fun fun fun...
Needless to say, my timing map looks very aggressive. But no knock... 
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Jun 22, 2010, 04:08 PM
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very interesting, i'll have to do some playing around with my timing in the spool range then. i'm sure i'll have to advance it even more since i'm on e85. what degrees are you running just as a reference?
Jun 26, 2010, 09:07 AM
#11
Here are some of my experiences with MIVEC and spool. Keep in mind this is on a Ralliart with a smaller turbo than the EVO X turbo, but it is single scroll vs twin scroll. Looking at peoples "stock" boost plots they seem to spool about the same stock.
On my old tune with stock cams launching the Ralliart at 3000 RPM (brake pressed and WOT) I was making 20 psi of boost at the launch. After putting in the new cams (Cosworth) I zeroed out my MIVEC maps to give me "smooth" operation and eliminate transmission slip by torque reduction vs making maximum power.... and the next time I went to the track I was only making 6 psi of boost at the launch. I have the next few days off and will be tweaking around lowering my boost pressure to limit low RPM torque and restore my MIVEC tables to see if this restores my spool up.
Later,
Keith
On my old tune with stock cams launching the Ralliart at 3000 RPM (brake pressed and WOT) I was making 20 psi of boost at the launch. After putting in the new cams (Cosworth) I zeroed out my MIVEC maps to give me "smooth" operation and eliminate transmission slip by torque reduction vs making maximum power.... and the next time I went to the track I was only making 6 psi of boost at the launch. I have the next few days off and will be tweaking around lowering my boost pressure to limit low RPM torque and restore my MIVEC tables to see if this restores my spool up.
Later,
Keith
Jun 28, 2010, 04:40 AM
#13
Here are some of my experiences with MIVEC and spool. Keep in mind this is on a Ralliart with a smaller turbo than the EVO X turbo, but it is single scroll vs twin scroll. Looking at peoples "stock" boost plots they seem to spool about the same stock.
On my old tune with stock cams launching the Ralliart at 3000 RPM (brake pressed and WOT) I was making 20 psi of boost at the launch. After putting in the new cams (Cosworth) I zeroed out my MIVEC maps to give me "smooth" operation and eliminate transmission slip by torque reduction vs making maximum power.... and the next time I went to the track I was only making 6 psi of boost at the launch. I have the next few days off and will be tweaking around lowering my boost pressure to limit low RPM torque and restore my MIVEC tables to see if this restores my spool up.
Later,
Keith
On my old tune with stock cams launching the Ralliart at 3000 RPM (brake pressed and WOT) I was making 20 psi of boost at the launch. After putting in the new cams (Cosworth) I zeroed out my MIVEC maps to give me "smooth" operation and eliminate transmission slip by torque reduction vs making maximum power.... and the next time I went to the track I was only making 6 psi of boost at the launch. I have the next few days off and will be tweaking around lowering my boost pressure to limit low RPM torque and restore my MIVEC tables to see if this restores my spool up.
Later,
Keith
Jun 28, 2010, 12:39 PM
#14
Yes, it went leaner... to about 14~ but it also produced fantastic spool... this on a stock AFR calibration table.
The stock injector calibration table actually forces the injectors to inject less fuel in the spool up area, one of the reasons why even with adding fuel there it still is a bit lean. I adjusted those pulse width areas to be 0 for more linear fuel control. It also made my spool richer and made me lose spool time. So now adjust the fuel map to make it leaner to gain spool again.
But if you use the stock injector calibration map. Then just adding timing will produce leaner spool, much quicker spool. I keep adding timing and taking away fuel for testing. Fun fun fun... Needless to say, my timing map looks very aggressive. But no knock...
The stock injector calibration table actually forces the injectors to inject less fuel in the spool up area, one of the reasons why even with adding fuel there it still is a bit lean. I adjusted those pulse width areas to be 0 for more linear fuel control. It also made my spool richer and made me lose spool time. So now adjust the fuel map to make it leaner to gain spool again.
But if you use the stock injector calibration map. Then just adding timing will produce leaner spool, much quicker spool. I keep adding timing and taking away fuel for testing. Fun fun fun...
Needless to say, my timing map looks very aggressive. But no knock... 
Jun 28, 2010, 05:03 PM
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hey hiboost, did gunzo do the gear based mivec for ya? i sent him my hex a while back but he hasn't contacted me about it for a while now 
do you know of anybody else that can do it?
do you know of anybody else that can do it?