From: Epijk@aol.com
Message-ID: <162.461611.28c523bc@aol.com>
Date: Mon, 3 Sep 2001 14:19:40 EDT
Subject: Re: TSIO550 Engine Modifications
To: lancair.list@olsusa.com
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Reply-To: lancair.list@olsusa.com

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In a message dated 9/2/2001 11:12:20 AM Pacific Daylight Time, 
gwbraly@gami.com writes:

<< Using our PRISM (Pressure Reactive Intelligent Spark Management)
 system we are able to do this almost effortlessly.  I have been able to
 operate these engines at 375 to 400 Hp with the peak cylinder pressures at
 or below the values traditionally seen with the engines in the stock
 configuration operating at 350 Hp.  >>

George:

Nice to hear from you regarding your work. We have read a lot in the Av Press 
about GAMI and other programs you're involved in.

Your comments regarding BMEP and combustion quality are well-understood. You 
have probably experienced the fact that many people misunderstand BMEP and 
fail to recognize that although is is derived from the conecpt of  mean 
cylinder pressure, it's purely a mathematical representation of net ("Brake") 
torque per cubic inch of displacement. The concept derivation (mean cylinder 
pressure) often masks the fact that one can increase BMEP by making changes 
which have absolutely nothing to do with the combustion process, such as 
installing a more efficient water pump, for example (lower power consumed to 
produce the same coolant flow, resulting in higher engine output power). 

I'd be very interested in learning more about the specifics of the LycoNental 
technology you developed which reduces the peak cylinder pressure while 
maintaining the same BMEP. It sounds as if (reading between the lines) that 
you've come up with a means of speeding up the burn rate and delaying 
ignition so as to reduce the negative torque which results from the large 
pressure spike before TDC.

Again, reading between the lines, the PRISM acronym suggests an active, 
real-time monitoring of cylider pressure and corresponding closed-loop 
control of teh spark event. Do you have any published info on the system (or 
unpublished info you'd be willing to share)?

At EPI, we have found some pretty significant power increases in certain 
high-performance engine combinations as a result of increasing the mixture 
quality (better homogeneity, smaller SMD particle size, etc.) and mixture 
motion (smaller port velocity gradients, more induction and compression 
swirl, "fast-burn" chamber technology, etc.) which allow us to remove as much 
as 8 degrees of advance.

We have not tried any of the "fast-burn" mods on LycoNentals, mainly because 
our recent engine development efforts have been focused on liquid-cooled 
technology. Because the chamber layout of both the Lyc and big Continental 
heads is so far superior to the compromised chambers available in lightweight 
pushrod V8 cylinder heads, we have been working on the development of a new 
cylinder head which attempts to capture some of the chamber and port 
advantages found in the best of the LycoNentals.

I assume that, in addition to your stated improvements in BMEP, you have also 
realized improvements in BSFC. If so, that could slightly reduce the net heat 
rejection load on the engine. However, the fact still remains that more HP to 
the prop means that more BTU's per minute must be removed from the engine, 
primarily the combustion chamber areas (heads, valves, piston tops). Although 
your fast-burn technology can result in better bottom-end reliability, you 
must know that the heat rejection load imposed by more power output doesn't 
change significantly (although we have found an interesting reduction in the 
DISTRIBUTION of heat-rejection resulting from the use of a particular 
coating).

Keep in touch.
Jack Kane
EPI, Inc  (www.epi-eng.com)
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