195 or 200 hp?

[johntwilcox]

Finishing up my Engine config, and I have a choice to make.

195HP and option to use 94 OctMoGas
200HP and limited to 100LL.

While I have 100LL locally, I'm thinking the MoGas option would be great, both for availability flexibility and cost.


Question: What if any practical difference will 5 HP make with an 8? ( other than bragging

My airport is 800 ft, so altitude not a concern, and I won't be trying to climb with any Harmons.

 

[Mel]

Finishing up my Engine config, and I have a choice to make.
195HP and option to use 94 OctMoGas
200HP and limited to 100LL.
While I have 100LL locally, I'm thinking the MoGas option would be great, both for availability flexibility and cost.
Question: What if any practical difference will 5 HP make with an 8? ( other than bragging
My airport is 800 ft, so altitude not a concern, and I won't be trying to climb with any Harmons.

No question by my thinking. You will see little to no difference in performance and the lower compression will extend the life of the engine and give you a larger margin of detonation.

 

[Mark33]

MOGAS

I vote for MOGAS. I’ve been running car gas (91 octane) for a long time and can’t imagine having to switch back to AvGas. If you stay 9:1 C/R or less and stay at standard 25* BTC timing until you fall below 65% power prior to advancing it, you’ll be just fine. Also, if you’re running a system such as SDS of EFII that has a high pressure fuel rail and return fuel system, vapor lock will never be an issue…even when running car gas.

 

[AeroEngineer]

100LL isn't going to be around for ever. Yes, I know that drop-in replacements have been developed, but... I have a feeling that, in the future, pilots whose engines accept lower-octane fuels will be glad for that flexibility.

 

[Carl Froehlich]

100LL isn't going to be around for ever. Yes, I know that drop-in replacements have been developed, but... I have a feeling that, in the future, pilots whose engines accept lower-octane fuels will be glad for that flexibility.

+1
100LL is too expensive - and the projection for 100UL replacements is they will be more expensive than 100LL.

Swift 94 seems like the logical stepping stone toward an unleaded future. As there has been no promotion of Swift 94 (as in multiple test sites to measure demand) it seems to me that our aviation champions are sticking to their “a drop in replacement for 100LL at any cost” stake in the ground.

Carl

 

[gfb]

Do you have convenient access to MoGas? Like a pump at your home base? I thought I'd be using a lot of mogas but it turns out there's nothing convenient near me.

When I want to go fly I don't usually want to deal with hauling 20 gallons of fuel in my car to the airplane

 

[Mark33]

Do you have convenient access to MoGas? Like a pump at your home base? I thought I'd be using a lot of mogas but it turns out there's nothing convenient near me.

When I want to go fly I don't usually want to deal with hauling 20 gallons of fuel in my car to the airplane

It’s unfortunate, but in my experience airports that have dedicated auto fuel pumps are somewhat rare. Fortunately though, on my primary cross country that I do every few weeks, there’s a field that does sell it, so I make it a point to stop there to top off the tanks.

As far as something for a home airport, you can build something fairly inexpensively. You can get one of those cheap little utility trailers from Northern tools or harbor freight and mount a 50-100 fuel transfer tank on it. Add some hose, a nozzle, and a pump and you now have a very convenient way to transport fuel out to your airplane and fill it up.

 

[Southern Pete]

Finishing up my Engine config, and I have a choice to make.

195HP and option to use 94 OctMoGas
200HP and limited to 100LL.
...

195hp

Are you saying 195hp from a parallel valve motor and 200hp from an angle valve?
The 200 hp from an angle valve is actually probably closer to 195, so I would take the lighter (and cheaper) motor everyday.

If this is a compression ration question in the same engine then you wont notice 5hp, go with the 195hp option.

Either way I would choose the "195"hp option.