Decalin instead of TCP?

On 07 Sep 2004 20:39:22 -0700, Bob Fry
wrote:

"It is an excellent additive for auto conversions, where it reduces
buildup on oxygen sensors and plugs. If you have to use 100LL, then
this stuff is for you. Prevents valve seat erosion from valve seat
micro welding. It is equivalent to TCP.

I am not a internal engine combustion expert, and don't play one on
TV, but I have a couple of thoughts to add regarding this statement:

The auto conversions I'm aware of tend to run cleaner than certified
aircraft engines regardless whether they are carburated or fuel
injected. This is because they normally run with a mixture closer to
the stochiometric ideal than do the aircraft engines during the
settings other than leaned for cruise.

Most auto engine conversions do not have fixed timing. The timing
adjusts as need be for the running condition. Some of them are using
full fledged auto fuel injection and timing computers which vari the
timing and fuel being injected many times a second according to the
sensors. With the full boat conversions, those using all the sensors
and computers, the timing and fuel mixture adjusts for all situations,
including altitude compensation. Unlike fixed timing engines, this
means the engines never get to the point where the peak pressure point
approaches top dead center where the pressure increase can cause
detonation at high power settings, because the computer keeps the
timing adjusted to prevent that. Tixed timing engines MUST use the
richer mixture for high power settings in order to retard the
mixture's rate of burn so that the PPP does not occur with the piston
at TDC. The rich mixture burns more slowly than a mixture that is
close to ideal.

With all this in mind, the auto conversions tend to run leaner
mixtures most of the time which ,(this is where opinion raises it's
head) should reduce lead buildup in auto conversions. Why? Because
the nearly ideal mixture ratio results in near complete combustion.

That's the way it looks to me anyway.

Corky Scott

Corky,

Bud just overhauled the heads on his Ford because it sat for a number of
years in Florida. He has been using 100LL almost exclusively. The head
shop found heavy lead deposits on the valves which they found difficult to
remove (probably forgotten how). It may be that TCP or similar product is
necessary in our Fords if we run avgas all the time.

Corky Scott wrote:

On 07 Sep 2004 20:39:22 -0700, Bob Fry
wrote:

"It is an excellent additive for auto conversions, where it reduces
buildup on oxygen sensors and plugs. If you have to use 100LL, then
this stuff is for you. Prevents valve seat erosion from valve seat
micro welding. It is equivalent to TCP.

I am not a internal engine combustion expert, and don't play one on
TV, but I have a couple of thoughts to add regarding this statement:

The auto conversions I'm aware of tend to run cleaner than certified
aircraft engines regardless whether they are carburated or fuel
injected. This is because they normally run with a mixture closer to
the stochiometric ideal than do the aircraft engines during the
settings other than leaned for cruise.

Most auto engine conversions do not have fixed timing. The timing
adjusts as need be for the running condition. Some of them are using
full fledged auto fuel injection and timing computers which vari the
timing and fuel being injected many times a second according to the
sensors. With the full boat conversions, those using all the sensors
and computers, the timing and fuel mixture adjusts for all situations,
including altitude compensation. Unlike fixed timing engines, this
means the engines never get to the point where the peak pressure point
approaches top dead center where the pressure increase can cause
detonation at high power settings, because the computer keeps the
timing adjusted to prevent that. Tixed timing engines MUST use the
richer mixture for high power settings in order to retard the
mixture's rate of burn so that the PPP does not occur with the piston
at TDC. The rich mixture burns more slowly than a mixture that is
close to ideal.

With all this in mind, the auto conversions tend to run leaner
mixtures most of the time which ,(this is where opinion raises it's
head) should reduce lead buildup in auto conversions. Why? Because
the nearly ideal mixture ratio results in near complete combustion.

That's the way it looks to me anyway.

Corky Scott

--
Bruce A. Frank, Editor "Ford 3.8/4.2L Engine and V-6 STOL
Homebuilt Aircraft Newsletter"
| Publishing interesting material|
| on all aspects of alternative |
| engines and homebuilt aircraft.|

On Thu, 09 Sep 2004 06:49:10 GMT, "Bruce A. Frank"
wrote:

Corky,

Bud just overhauled the heads on his Ford because it sat for a number of
years in Florida. He has been using 100LL almost exclusively. The head
shop found heavy lead deposits on the valves which they found difficult to
remove (probably forgotten how). It may be that TCP or similar product is
necessary in our Fords if we run avgas all the time.

Well, there you a actual experience trumps conjecture most of the
time. I humbly bow to the superior information.

Ron, as to the oxygen sensor, some very clever people have managed to
fake out the system by sending a trace voltage to the computer making
it think the sensor is working. Don't know how the computer then
knows how to adjust for all conditions when the signal to the computer
from the O2 sensor is fake though.

Having to fake out the computer, along with having to depend on the
single source for your ignition AND timing is why I've chosen not to
go that way. Well, that and not wanting to pay for injection capable
heads and the fuel pump, rails, plumbing, injectors etc etc for a fuel
injection system.

Corky Scott