There has been discussions about the cam gears and those "tuners" determined that the majority of cams do not benefit much, if any, from settings other than 0,0.

By doing what you suggested you decrease valve overlap. I see how this could increase the heat. Certainly, as in other suggestions, there is a limit as to what can be done here. You end up opening the intake cam sooner and closing the exhaust cam later....right ? ?

Also, there would be a compromise with tuning the cam gears....what you do for bottom end you would lose at top end....right ? ?

Wouldn't setting the cam gears with + intake and - exhaust cause some issues at idle though? ? ?

 

What I was experienced is that if I Increase the timing and increase the fuel at range 2500-4500 rpm will increase boost faster.
Faster spool means faster exhaust gas.
If you will produce more kinetic energy you will produce more heat.
You can also create more heat with richer AFR and more timing.
Or if you retard the ignition timing on range 3000 to 4000 rpm will help you to burn slower and will push more hot air into the Exhaust and spin the turbo.
How you set your BDEL, TBEC and WGDC tables?

 

I think all this timing talk depends on turbo setup and cams.

eg, Green with HKS 272 needed loads of timing to make it shine (2.3 bar peak), whereas AMS 35r and kelfords 282/272 are the opposite.

 

Of course timing talk depends on the setup. But there are key "ideas" that work to enhance a turbo's ability spool.

Example look above at Danieln.....he found that increasing timing and fuel at the 2500-4500 range helped his spool.

I found similar results with adding fuel in the spool areas. I was running too lean. Which required me to have less timing to avoid knock. By increasing fuel to be closer to the "sweet spot" (mid 12s afr during spool) I was able to make timing adjustments that also enhanced spool.

 

Another thing ...... a smaller exhaust housing will help to spool faster, but it will lose some power up top.

I did some tests about this and like you say....every car is different....

From my point of view these are the ways for faster spool:

1.raise AFR ratio at the lower RPM's (a richer mixture creates more exhaust heat and will spool turbo faster).

2.raise engine compression.

3.cams (less overlap uses exhaust gas more efficiently than blowing back into intake- known as reversion).

4.raise timing at lower RPM's ( it will give more power so you will have more exhaust. More exhaust will give you faster spool).

5.decrease turbo exhaust size.

 

Ooo yeah......and if none of those will not work.......just go for Nitrous

 

A nice update will be also the "Rocket System" from Prodrive used in WRC applications.
The system launch the car at 1800-2200 with 47 PSI.

This device is fitted to the header just in front of the turbo and works as a sophisticated anti-lag system.
Air and fuel are fed into a combustion chamber and ignited by a spark on over-run, it can be used in three stages (depending on how long you want the engine to last) and is the cause of the load banging noise that can be heard as these cars pass by and the flames coming out of the tail pipe. This system is used in conjunction with the boost pack which stores excess pressure in it's own reservoir to be fed back into the engine inlet side of the inter cooler when the throttle is depressed after shut off.
All this is coupled to the "flat change" gear shift and launch control system which is of course controlled the the ECU.

Prices:
WRC Header £2,200
WRC Turbo £10,000
Boost Pack £3,000
ECU £5,000
Engine Wiring Harness £3,000




Here is a short movie with the rocket system in action.
You will hear the sound difference between a normal ALS launch system and a Rocket System.

http://www.youtube.com/watch?v=LpBiZYVfTp8

 

thats INSANE....

 

I take it the subaru's were the only ones with that rocket system?

 

Too bad no turbo manufacturer has developed a way to have an adjustable nozzle on the turbo hot side as a method for controlling spool.

It is common knowledge that smaller hot side spool faster because they have less room for volume of flow, thus higher pressure.

By making the hot side adjustable you could have the best of both worlds with any turbo.....fast spool and big top end power.

 

Um... Holset DOES that, it's called a Variable Geometry Turbo.

 

A lot of you are recommending porting the exhaust manifold to have a larger diameter inside to help with spool. I would have guessed that that would actually hurt it. I would have guessed larger diameter would just be for power and not spool times.

 

Garret and Borg Warner do. the 997tt has them from the factory.

http://www.turbos.bwauto.com/products/vtg.aspx

http://www.youtube.com/watch?v=Gc2awh0O0Bc

d

 

Those BW are for diesels which have much lower ETGs than our Evos. The 997s are 3.6 capacity, but have one turbo per bank, so are speced to flow for a 1.8 ltr capacity. Not much help there, and I suspect they might be hard to get hold of and very expensive.

 

Where I live at altitude it is common to advance the intake cam which does reduce overlap. The real benefit is the earlier closing of the inlet valves which acts somewhat like you have a higher compression ratio. The spool is several hundred RPM's sooner than having it at 0,0.

With my AMS 2.3 and a BBK lite under load I can have full boost (28psi) in 4th and 5th by 2000 rpms on 91oct (and I am at 7200ft). I love the car like this for the street, for a track day I would put them back at 0,0 to get the top end back.