[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: VW & Audi cylinder head port info needed...

OK, this is wordy but you opened the can.

When we talk fuel, we talk BTU's. The more fuel you can burn, the more heat
you can extract from that fuel, the greater/faster the expansion of gasses,
the more power you produce.
Detonation is caused by the spontaneous ignition of the A/F mixture
(exploding). This is a result of too much compression for the fuel used, hot
spots, normal ignition starting too far in front of TDC or oil contamination
of the intake charge (ever drive an old Audi with leaking valve stem
Octane and timing we control during set-up. Oil control is clearances/engine
condition. What you refer to regarding heat in the combustion chamber is
controlled by intake charge and the ability of the chamber materials/design
to dissipate the heat of combustion. Ceramic coatings shield the more
fragile metal components from extreme heat reducing the heat transferred
into the metals and the thermal load on the cooling system. The ceramic
coating is very thin so dissipates its own retained heat quickly. Combined
with proper smoothing of combustion chamber (and piston) edges, protective
coatings result in a reduction of hot spots which can cause detonation. With
proper coatings, a normally aspirated engine can operate at up to approx.
1350 F and forced induction to 1600 F continuous measured 1 inch from the
exhaust port. Without the coatings, at those temperatures, you have
This all adds up to less heat going into heating the engine and more into
producing power. What's left over goes out the tail pipe.

Bryan Doughty
----- Original Message -----
From: <JShadzi@aol.com>
To: <eurocar@gci.net>; <quattro@audifans.com>; <OorQue@aol.com>
Sent: Wednesday, July 14, 1999 4:55 PM
Subject: Re: VW & Audi cylinder head port info needed...

> In a message dated 7/14/99 7:55:26 PM Eastern Daylight Time,
> writes:
> << ideal situation would be to use stainless intake, Inconel exhaust,
>  coat the chamber, piston top, valve faces and exhaust ports after
>  The last stainless 7mm valves I got were custom made, we had to cut to
>  length and the keeper groove.
>   >>
> Not to say its wrong, but just a thought.  Does'nt all this ceramic
> coating keep a lot of heat in the combustion chamber, increasing the
> liklyhood of detonation?  Just curious to see what you experience has
> Javad