I read this over on another forum... Im not going to try it, just never heard about it before.



Says that with increase EGT's exhaust gases expand more.. and will cause the turbo to spool faster.. Kinda like a bigger motor?

Im assuming he just does this before he hits full boost..

??

 

No, I see another problem with the map too.

By decreasing ignition right before spool up but at high load your ARE increasing EGTs, but the engine will be slower because....well......you're not making as much power as you can for that map range .


2.) That little firball part is kinda cool to watch, but he has to hit those columns WITHOUT hitting fuel cut (rare when shifting) and it also risks burning a valve.

Use an anti-lag if you can. This applies that "theory" but does it correctly

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">By decreasing ignition right before spool up but at high load your ARE increasing EGTs, but the engine will be slower because....well......you're not making as much power as you can for that map range .</TD></TR></TABLE>
You are not making as much power because most of the energy used to push the piston down is now going out the header and into the turbine; thus, faster spool.

 

It is not unheard of to use higher EGT's to increase spool. There are different ways of going about it though and its kind of a touchy thing. Some people run a bit lean just before the transition into boost and maybe for the first few degrees. This is a spot in which you do not risk detonation nearly as much.

Do this at your own risk though. Most power gains carry a risk with them as well.

 

I was hoping someone wouldn't go into this and just trust me it's not good haha. Well true you do build a fragment more of boost, but then your map readings are on the boost portion of the map where you then are needing more ignition retard to keep the boost at it's level until the revs reasch the correct amount. Essentially you are boosting more but not making the power/acceleration you should if you were in OR out of boost. Kinda hard to understand I know . Keep the power and boost curve as linear as possible it's the best.

Here is a small comparison I just thought of. Think of how far you need to shoot a cannon ball. Obviously the furthest it will go will be the cannon at 45*. Like boost if you boost it too soon then you will have too high/low of angle and thus not optimal. Now then I always hear .... "so why is anti-lag used." I answer by saying that it isn't usefull unless you have a.) traction and b.) you can hold the revs were they need to be for good spool . Hope this helps

 

I personally would NEVER do that for numerous reasons that adseguy said. When you retard the timing like that you are losing that energy to force the piston down, superheating the chamber, and throwing mad egt's at your turbine wheel. Most rally cars and "old school turbo formula 1" cars employed anti-lag technology but these cars had short turbo lives and were replaced often and had VERY exotic material that could withstand those temps. Now many of the new turbos employ this technology to a degree but would you want that on your street car with a budget, hell no!
For me I like to use the soft-cut rev limiter and this can sometimes be employed between shifts to keep the turbo spooled. Like other limiters you can hold the throttle wide open and set your rpms to the desired launch rpms. I like the soft cut because it cuts spark to one spark plug at a time to hold the engine revs to the rpms set. With spark alternately being withheld from the plugs, unburned fuel passes into the exhaust along with the unburned oxygen from that cylinder. Once in the exhaust manifold the hot exhaust gases ignite the air/fuel mix to drive the turbine. Because spark timing isn't retarded with this arrangement, the exhaust gases are cooler. Hence afterburn combustion is relatively slow and incomplete, so turbo temps do not climp to dangerous levels which is why i like it for street cars.
Not only that but each time the clutch is depressed at engine rpm higher than set in the rev limiter the turbo runs in afterburn mode. Therefore the turbo is able to maintain its speed during gear changes or from a standing start. It is not the afterburn alone that does this, but rather can it also be partly attributed to the fact that the throttle is open during this period and air pumped by the compressor is free to course into the engine, rather than blowing off. With this system inexperienced drivers can just hold the throttle wide open, clutch, shift, and keep the gas mashed without overrevving the engine. I got a little carried away but I hope that gives a little info on this subject of lag........
Ryan