Spool Time

[Dave_Harris]

Givin the following setup -

Bailey's 2-Step set to 2600 rpm
Stage right tranny brakeAny
PTC 2800 stall
Fast XFI engine management

What's going to spool up the turbo faster:

retarded timing / rich mixture
retarded timing / lean mixture
advanced timing / rich mixture
advanced timing / lean mixture

Looking for consistant boost level in a short amount of time (from the time I stage till the time the go light comes on). The time frame can be as short as 3 seconds, and as long as 10 seconds or more. My current setting is a slightly lean condition (13:1) with the 2 step pulling out 8 degrees of timing. This allows a launch boost level of 7 psi after a short 4 sec stage, but if I'm in the beams for longer the boost level rises to 9 or 10 psi.

I'm trying to find a way to stage, go WOT on the 2 step, and build a consistant level of boost no matter how long I'm on the box, whether its 3 secs or 10 secs.

Any suggestions welcome

 

[Phoneguy]

I would bet that Cal can get you setup, with the XFI controlling boost, and cutting the ALKY while on the brake

Bryan

 

[Dave_Harris]

I believe boost contol that low would require a boost controller with an external boost reference source such as the AMS1000 with CO2 and an external waste gate setup (if I understand everything correctly). I'm kinda hoping I can find something a little less involved (and a little cheaper )

 

[Quik Six]

Givin the following setup -

Bailey's 2-Step set to 2600 rpm
Stage right tranny brakeAny
PTC 2800 stall
Fast XFI engine management

What's going to spool up the turbo faster:

retarded timing / rich mixture
retarded timing / lean mixture
advanced timing / rich mixture
advanced timing / lean mixture

Looking for consistant boost level in a short amount of time (from the time I stage till the time the go light comes on). The time frame can be as short as 3 seconds, and as long as 10 seconds or more. My current setting is a slightly lean condition (13:1) with the 2 step pulling out 8 degrees of timing. This allows a launch boost level of 7 psi after a short 4 sec stage, but if I'm in the beams for longer the boost level rises to 9 or 10 psi.

I'm trying to find a way to stage, go WOT on the 2 step, and build a consistant level of boost no matter how long I'm on the box, whether its 3 secs or 10 secs.

Any suggestions welcome

Curious to what 60' you have achieved and what you expect to achieve.

 

[Phoneguy]

No AMS1000 needed. The XFI will control boost. I dont claim to know how well as mine is not yet connected. I have the solenoid and the connection made, just dont have a program yet to even play with it .

Bryan

 

[bison]

You need to use a controller to do it. Advanced timing/power mixture will make more torque and the converter will flash higher. You need to try different things and nip away at it. Once everything gets heat soaked it will spool a little slower. In better air spool will be faster.

 

[Dave_Harris]

Curious to what 60' you have achieved and what you expect to achieve.

At 6 psi, it 60's at 1.55. At 9 psi it has gone 1.48

I just want to max out boost for a given RPM on the 2 step, and be able to reach that boost level in 3 secs or so..... Trying to get a consistant and repeatable 60' no matter how long I'm on the brake.

Yes, I'm pulling timing via 2 step. I'm going to run some tests this weekend to see what spools better, retarded timing vs advanced timing and rich vs lean. I'm also curious to see if setting the 2 step rpm to the stall speed of the converter changes anything.

 

[Dave_Harris]

No AMS1000 needed. The XFI will control boost. I dont claim to know how well as mine is not yet connected. I have the solenoid and the connection made, just dont have a program yet to even play with it .

Bryan

As for as I know, you cannot control boost lower than your actuator / wastegate spring. If I'm wrong, pls let me know!!

 

[RmvBfrFlght]

Lower SA and richer will spool quicker. Doing this dumps a lot of heat into the exhaust and is also hard on the exhaust valves. I've played with doing this a little, but didn't like doing it for said reasons.

RemoveBeforeFlight

 

[bison]

As for as I know, you cannot control boost lower than your actuator / wastegate spring. If I'm wrong, pls let me know!!

You are correct and ambient conditions will change things. Something that senses boost and increases/deceased is needed to have repeatable boost while staging.

 

[Dave_Harris]

So, in a simplified setup - I could run an external gate with a 6 lb spring, then run a regulated pressure source from a CO2 bottle at 19psi to the top of the wastegate through a solinoid valve activated by the tranny brake. Get on brake, boost up to the 6psi wastegate, then when tranny brake released, sol would open allowing 19psi on top of wastegate, keeping it closed until boost hit 25psi ?????????

 

[kidglok]

what number are you pulling 8 degrees timing from?

 

[Dave_Harris]

what number are you pulling 8 degrees timing from?

28 degrees

 

[kidglok]

28 degrees

I would be careful with that, 13 a/f and 20* timing you run the risk of melting an exhaust valve, especially staging for upwards of 10 seconds.

There is 2 schools of thought on spooling a turbo (especially on launch):
1. High timing and lean a/f
2. Low timing and a richer a/f

ive found a point with my setup at 12.3 a/f 25* timing 3200rpm on the 2tep i will reach 7psi in about 3 seconds and the motor cannot push the boost past that point no matter how long i sit there. Obviously the stall of the converter and turbo size play a big role in that as well (amogst other things) but that is with an ams1000 with a 15lb spring in the gate using only manifold pressure with no launch assist from the controller

here is a good explanantion of things:

"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.

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. .

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 you really need to find the right balance. 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."

 

[Dave_Harris]

Thanks kidglok, I'll play with it and see how that does.

 

[norbs]

I would say what ever puts more load on the converter, hence more power more rpm will spool the turbo faster from the volume, so advanced timing and best af ratio for power. Once your have a few psi in the turbo then I would do the timing retard and rich mixture, but not before your turbo has a few psi already built up. You retard the timing and make it pig rich its going to be a slug to come on boost from no boost at all. It may not even be worth it to to the retard, a log would show any improvements, or worse results by doing this.

On another note if you had a properly sized gate you could run 2.5-3 times the gate psi without co2. The fast boost control is real tricky and time consuming to set up. It needs improvements to prevent spiking, as it has a tendency to keep the gate at 100% then try to open at the last second, which is usually too late, and no easy work-around to prevent this.

 

[murphster]

So, in a simplified setup - I could run an external gate with a 6 lb spring, then run a regulated pressure source from a CO2 bottle at 19psi to the top of the wastegate through a solinoid valve activated by the tranny brake. Get on brake, boost up to the 6psi wastegate, then when tranny brake released, sol would open allowing 19psi on top of wastegate, keeping it closed until boost hit 25psi ?????????

To get what you're wanting, this is the route you will have to go. With just an internal gate and 2-step the boost will rise the longer you are at the tree like you've noticed. If you go to an external gate and an electronic boost controller, using a weaker spring such as 6-9lb spring will let you keep low boost at the tree and allow more boost up top, but the spool up from launch boost to top end boost will be very poor. You would need to run a stiffer spring combined to cranking down the top bolt on the wastegate to get the boost rise to be fast. But with a stiff spring you'd be back to the same problem of the longer you are at the tree the more boost you will build because even with the electronic boost controller and solenoid bleeding off pressure it still cannot be less than the spring pressure.

So this is why you need the CO2. You can use a weak 6lb spring so you can launch at lower boost and keep it nice and steady no longer how long you are on the tree. And then after launch, with the CO2 pressure to the top of the spring you are running an equivalent stiffer spring to get to your boost goal as fast as you can. So it's the best of both. If you combine this with the 2 step launch control then you can choose the rpm you want your boost launch to be at so you can be hitting the converter at the right rpm.

You can also run an AMS500 or MSBC boost controller to accomplish this if you want to save money. They can be found used at decent prices. Running them in wastegate mode has given me the best results where you control how much pressure is directed to the top of the wastegate like you described. It takes some trial and error to figure how much pressure gives you what amount of boost but it's not so bad. Also, setting the CO2 regulator to a higher pressure such as 40-50psi seems to give me the best spool and control.

Overall, it's pretty expensive to convert from an internal wastegate over to an electronic external CO2 setup, but it gives you the most control. You can also have stages and ramps to dial in the boost too.

 

[Dave_Harris]

So I went all out.... I installed an AMS1000 boost controler w/co2, along with an external gate downpipe, and PTE 46mm wategate (thanks for getting me everything so fast Hartline!!). This way I can run a light spring in the wastegate and have some CO2 on top of it to limit myself to 6psi boost on the 2 step, then increase the boost after the tranny brake is released.

everything worked as expected. Made 4 runs before the rain hit and had the following 60' times -

1.626
1.625
1.625
1.624

Ran a 7.241, 7.243, 7.240, and a 7.170. I'm gonna blame change in weather conditions on the 7.170, it really cooled down right before the rain started.....

3 pound spring in wastegate, 3 pounds co2 on the launch (2800 rpm), 20 pounds co2 downtrack. Lauch boost was 5.7 everytime, and down track boost was 24 pounds.

 

[jasjamz]

I don't think you can get any more consistant than that. Congratulations!

 

[HighPSI]

You got yourself a bracket racer. Great job!