launch control ignition cut with hidro lifters

[cruz177]

Good morning, I would like to know if I am trying to use a launch control with hydraulic lifters and a low boost turbo that ignition retard would be safe as a general rule of thumb.

I understand that over -5 degrees should be safe with fuel cut, what, but also with ignition cut?

What is the best way to know if I am on the correct amount of fuel enrichment? Too much fuel will clean the cylinder walls and too little will raise the temperatures?

Thanks

[Adamw]

The fuel trim is generally used along with the retard value to tune the level of boost you can reach while on the launch limiter.  More retard and more fuel means more heat energy in the exhaust which means higher boost.  

The main thing you need to be careful of with hydraulic lifters - especially with stock valve springs is large and regular bangs in the exhaust. Each bang can lift the valve a little and the lifter fills to take up that extra lash.  With each bang the lifter pumps up a little more - until eventually you get to the point that either the valve no longer seals closed enough for combustion to occur, or a rocker jumps off, or a valve hits a piston, or sometimes all 3!   

There are often no obvious signs of the lifter pump - except sometimes a misfire that recovers slowly after the limiter has finished, so it is often experience with a specific engine that will identify it.  

[cruz177]

9 hours ago, Adamw said:

El ajuste de combustible se usa generalmente junto con el valor de retardo para ajustar el nivel de impulso que puede alcanzar mientras está en el limitador de lanzamiento. Más retardo y más combustible significa más energía térmica en el escape, lo que significa un mayor impulso.  

Lo principal con lo que debe tener cuidado con los elevadores hidráulicos, especialmente con los resortes de válvula originales, son los golpes grandes y regulares en el escape. Cada golpe puede levantar un poco la válvula y el levantador se llena para tomar ese latigazo extra. Con cada golpe, el levantador bombea un poco más, hasta que finalmente se llega al punto en que la válvula ya no se sella lo suficiente como para que se produzca la combustión, o un balancín salta, o una válvula golpea un pistón, ¡o a veces las 3!   

A menudo, no hay signos obvios de la bomba elevadora, excepto a veces una falla de encendido que se recupera lentamente después de que el limitador ha terminado, por lo que a menudo es la experiencia con un motor específico que lo identifica.  

Thanks for your answer, so is it preferable to have an ignition time as close to BTCD 0 and more fuel, or less fuel and a negative ATDC time?

[Adamw]

You will have to experiment to see what gives you the required result with minimal bangs, every engine is different .