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Posted for "George Braly" <gwbraly@gami.com>:
Yes.
Maybe 95% 100LL and 5% 92(R + M)/2.
Seriously… the TSIO-550 at 350 Hp is one of the three or four most difficult
engines with respect to detonation, after two or three Lycoming 350 Hp
engines.
It is not a vapor pressure issue. It *IS* an octane issue.
The vapor pressure is mostly a climb to altitude without vapor lock issue.
Yes… I have blended fuels and do have dyno results in a variety of
combinations. But there is superb published data on a lot of this.
I can run a 350 Hp TIO or TSIO engine to only about 210 to 230 Hp on premium
car gas. Then all hell breaks loose. Not a pretty sight. And that is at
modest CHTs. Add on hot day or altitude conditions and it gets worse.
We can run the most difficult engine in the fleet (TIO-540J2B) with PRISM
under hot day certification conditions and do that on unleaded Avgas. MON
about 92. But that is a very different fuel than 92 (R+M)/2 car gas, which
has a MON of about 87.
Regards, George
_____
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of John W.
Cox
Sent: Tuesday, March 29, 2005 8:20 PM
To: Lancair Mailing List
Subject: [LML] George or Craig for combined wisdom
With your combined knowledge of mechanical engine function can you address
the following?
Is their a point (Mixing Ratio) of combining 100LL AVGAS with 92RON or better
MOGAS that the Reid Pressure Number stays low enough that Pre-Ignition or
Detonation is not a factor in the Continental TSIO-550, TNIO-550, IO-550 or an
M14P Radial. With the fluctuating price of refined fuels and talk of mixing
these or using auto engines (alternatives), it has me wondering. I had heard
mention that the radials can handle a blend. Have you ever obtained dyno
results on blended fuels with these powerplants? Is this a potential with the
PRISM system?
John W. Cox
[ I through the PRISM "mags" wouldn't fit on an overhead induction cont
like the TSIO-550 and IO-550 ?? -Rob ]
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