I've Read Somewhere That Retarted Timing Causes Higher Temps

[ryan101]

As above, just wondering how much it would effect temps

[Galois]

If you're referring to the rich and retard limp mode the engine goes into some times then the temps are lower because the fuel mix is richer.

But if you're strictly talking about timing, i doubt it'd make much difference. The fuel is ignited slightly earlier in the piston cycle with advanced timing so the explosion has slightly longer to combust which means slightly more heat will go into the engine. Also having the explosion in a smaller space (the point of advancing timing) will mean the air-fuel mix will be more compressed and transfer the heat better to the metal, and the explosion will be more violent due to the small space (high pressure) and take less time adding to the heating of the engine. But giving the small changes usually made in changing timing it probably wouldn't make much difference.

I can't imagine any of these would play anywhere near as much of a role in engine temperature as air fuel ratios though.

[Trozzle]

This is in relation to exhaust temperatures. The further you retard the timing, the hotter the combusted mixture is when it leaves the cylinder. Think of it in extremes - if you retarded the ign timing so far that it was igniting the mixture just as the exhaust valve opened, you would have the mixture burning straight out the manifold. This would be bad.

[mad082]

This is in relation to exhaust temperatures. The further you retard the timing, the hotter the combusted mixture is when it leaves the cylinder. Think of it in extremes - if you retarded the ign timing so far that it was igniting the mixture just as the exhaust valve opened, you would have the mixture burning straight out the manifold. This would be bad.

that would be an anti-lag system

[Trozzle]

Antilag just doesn't spark at all I believe. It allows unburnt air/fuel mixture to leave the cylinder, which ends up ingniting in the manifold, and spools the turbo significantly. This gas also has a negative effect on the life of the turbo, as it's making it a lot hotter than it normally would be.

If you're correct Marc, and antilag is simple extremely retarded timing, then my point still stands - it's not good for the turbo lol

[mad082]

yeah i think you are right about the lack of spark ignition, but yeah the principle is pretty much the same.

i think that in normal conditions though, the retardation of the timing by 1 or 2 degrees is going to have a very minimal effect on EGT's.

[Trozzle]

yeah that small is nothing.

I remember speaking to my tuner when I was having my car finished up just the other week...he was saying about the measures they took to keep the max power DOWN, by retarding the timing up top. He then went on to explain that they could only do this so far, until the exhaust temps got too hot...I love it when you don't even need to pick a mechanic's brain for him to feed you with good information as they just tell you everything anyway.