reducing spool times

[dwdsm]

I think this would make a good Newbie or turbo tech thread. Alot of people get into turbos to big and want to decrease the spool time. So lets make a list of things that help spool. I'll add a few and others can jump in. Just don't forget it's a give and take kinda thing. Some of these may cause lower topend.

Equal length manifold.
Bagging the turbine side of the turbo.
max timing pre spoolup then ramp down accordingly.
properly matched intercooler and short route piping.
Small/stock cams.

c'mon jump in.

[kahl23]

More displacement
Higher compression
Smaller A/R turbine housing
nitrous

[andy4g63]

Lower/retard/ the pre-spool timing and make it a little rich at the same time, at these same RPM's . A smaller TB would help too.

[soldave]

Originally Posted by andy4g63

Lower/retard/ the pre-spool timing

Originally Posted by dwdsm

max timing pre spoolup then ramp down accordingly.

So which one is it?

[T9S1i]

yeah really ive heard both before!!!

Im about to do some tuning on my s258 setup so i'd like to know!

[wishihadatalon]

retarded timing will make boost faster but advanced timing will give you better off boost power. To me the minute gains in spool time do not offset the dog feeling that I have seen with running the low timing.

[dwdsm]

Mine is maxed pre boost and I guess I should of logged before and after but it feels like it has more nuts off boost. Now I don't know if this is because of the motor making more off boost power or the boost comming on sooner. I guess after the insight it's more power from the motor off boost. So Good imput. If I get spunky I'll throw in the old map and compare the numbers with a max timing run.
I guess it's the same as...
*note* lighter drivetrain parts will increase accelaration but not spool.

Would a ported head/oversized valves decrease spool due to the higher volume?

[aero_sallee]

Variable A/R housing if you are ambitious and haven't picked a turbo yet.

[mach4g63t]

Check this thread out...

Spool Tuning

Originally Posted by wishihadatalon

retarded timing will make boost faster but advanced timing will give you better off boost power. To me the minute gains in spool time do not offset the dog feeling that I have seen with running the low timing.

And Higher Compression pistons will help you feel a little better off-boost response, while allowing you to retard the timing for the pre-spool tuning mentioned in the link above. Sort of the best of both worlds?

[dwdsm]

Originally Posted by mach4g63t

Check this thread out...

Spool Tuning



And Higher Compression pistons will help you feel a little better off-boost response, while allowing you to retard the timing for the pre-spool tuning mentioned in the link above. Sort of the best of both worlds?

Your right I'll probally go 9:1 next time. Also less oil killing blowby

[dwdsm]

Originally Posted by aero_sallee

Variable A/R housing if you are ambitious and haven't picked a turbo yet.

That would be sick, If it was made. I don't know of such a thing...

[andy4g63]

[quote=soldave;151605832][quote=dwdsm;151605451]
max timing pre spoolup then ramp down accordingly.

So which one is it?

There is guy here on forums,1992awdlaser, he is a wiseman, he could explain much better, than me, but basically by retarding the timing, means igniting the fuel later and while burning exhaust valves opening. This is sort of how ANTI-LAG works.
Kind of the same with enrichening the AFR"s in pre-spool times too.

[DSMunknown]

Downshifting.

[2FoX2]

To go along with what dwdsm said, equal length manifold, combined with a high flow exhaust system will decrease the spool time.

[delta448]

Decreasing airflow restrictions at the compressor inlet (think MAFT, true CAI setup).
High-temp insulating exhaust wrap on the manifold.
External wastegate with an EBC.
A true divided turbine housing with the appropriate true divided manifold.
Removing exhaust restriction after the turbine; think no-cat, large dia. piping, DP cutout, etc.
Good results from a boost leak test.
Retarding the exhaust cam a couple of degrees.

[1992awdlaser]

What you want to do is retard the timing and add fuel pre-spool.

Retarding timing will make it spool faster. It does this because more of the heat from the power stroke goes into the exhaust manifold. I will try to explain each.

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.

[dwdsm]

Originally Posted by 1992awdlaser

What you want to do is retard the timing and add fuel pre-spool.

Retarding timing will make it spool faster. It does this because more of the heat from the power stroke goes into the exhaust manifold. I will try to explain each.

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.

Good imput thanks!

[crimsondragon]

Originally Posted by 1992awdlaser

What you want to do is retard the timing and add fuel pre-spool.

Retarding timing will make it spool faster. It does this because more of the heat from the power stroke goes into the exhaust manifold. I will try to explain each.

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.

Doesn't antilag also kill turbos? I rather keep the turbo lag if it means I'd have to replace my turbo in a few thousand miles.