Author: "bobbarrow747" <bobbarrow@...> Time: Mon Mar 22, 2004 3:24 am PST Link
I'm procratinating about a Lyc O320 vs O360 for my RV7A. I need to
be able to get good range for some long over water trips I intend to
make. People tell me that power output is purely a function of fuel
burn regardless of engine capacity. On that basis an O360 at the
same fuel burn as an O320 should produce the same horsepower. It
therefore follows that if you throttle back sufficiently on an O360
you should get the same range as an O320. Is this true. I flew
recently with a friend in his RV7A (O360 and FP Sensenich). At 8000'
I was amazed to note the fuel burn was only 20 litres/hour when he
dropped the revs back to about 2000....and we were still doing 130
kts. I got a bit excited about that.
But there are two doubts I have in my mind on this issue.
Firstly, given equal power output the O360 will always have to be at
a lesser percentage of total power than an O320. This means that the
carburettor butterfly valve will be more closed forcing the engine
to work that little bit harder to suck in air (not as efficient). Is
this true. Is this really relevant to range in any meaningful
sense.I am told that Lycoming engines perform most efficiently at
about 8000' because that's when the engine produces cruise power at
full throttle (no air restriction).
Secondly, is it a problem to fly an O360 for long periods at a quite
low percentage of total power. Is there any bottom line...except of
course for the run-in period.
I realise of course that an O360 weighs a bit more than an O320 so
it has to haul its own weight...but that should be relatively
insignificant in terms of range.
I'd like to have the O360 for when I need the power, but I'd like to
think that I can have the fuel efficiency of an O320 when I throttle
the O360 back........Am I living in a fuels paradise?
Author: "midniteoyl2" <midniteoyl@...> Time: Mon Mar 22, 2004 2:21 pm PST Link
Seems to me that running at 55% on a 360 wouldnt hurt it at all...
and be about the same as 65% on a 320
Jim
--- In vansairforce@yahoogroups.com, "bobbarrow747" <bobbarrow@o...>
wrote:
> I'm procratinating about a Lyc O320 vs O360 for my RV7A. I need to
> be able to get good range for some long over water trips I intend
to
> make. People tell me that power output is purely a function of fuel
> burn regardless of engine capacity. On that basis an O360 at the
> same fuel burn as an O320 should produce the same horsepower. It
> therefore follows that if you throttle back sufficiently on an O360
> you should get the same range as an O320. Is this true. I flew
> recently with a friend in his RV7A (O360 and FP Sensenich). At
8000'
> I was amazed to note the fuel burn was only 20 litres/hour when he
> dropped the revs back to about 2000....and we were still doing 130
> kts. I got a bit excited about that.
>
> But there are two doubts I have in my mind on this issue.
>
> Firstly, given equal power output the O360 will always have to be
at
> a lesser percentage of total power than an O320. This means that
the
> carburettor butterfly valve will be more closed forcing the engine
> to work that little bit harder to suck in air (not as efficient).
Is
> this true. Is this really relevant to range in any meaningful
> sense.I am told that Lycoming engines perform most efficiently at
> about 8000' because that's when the engine produces cruise power at
> full throttle (no air restriction).
>
> Secondly, is it a problem to fly an O360 for long periods at a
quite
> low percentage of total power. Is there any bottom line...except of
> course for the run-in period.
>
> I realise of course that an O360 weighs a bit more than an O320 so
> it has to haul its own weight...but that should be relatively
> insignificant in terms of range.
>
> I'd like to have the O360 for when I need the power, but I'd like
to
> think that I can have the fuel efficiency of an O320 when I
throttle
> the O360 back........Am I living in a fuels paradise?
Author: "Jack Lockamy" <jacklockamy@...> Time: Mon Mar 22, 2004 3:23 pm PST Link
Jim (and others....),
I've heard from some 0-360 users that it is the "self-discipline" of running at only 55% that is the problem with fuel conservation to match the 0-320 fuel usage.
When you have the extra ponies, you tend to use them and thus the fuel savings disappear. :-).
Your "mileage" may vary (pun intended),
Jack Lockamy #71103
RV-7A 0-320 slider
still under construction
----- Original Message -----
From: midniteoyl2
To: vansairforce@yahoogroups.com
Sent: Monday, March 22, 2004 2:07 PM
Subject: [VAF Mailing List] Re: Living in a fuel's paradise
Seems to me that running at 55% on a 360 wouldnt hurt it at all...
and be about the same as 65% on a 320
Jim
--- In vansairforce@yahoogroups.com, "bobbarrow747" <bobbarrow@o...>
wrote:
> I'm procratinating about a Lyc O320 vs O360 for my RV7A. I need to
> be able to get good range for some long over water trips I intend
to
> make. People tell me that power output is purely a function of fuel
> burn regardless of engine capacity. On that basis an O360 at the
> same fuel burn as an O320 should produce the same horsepower. It
> therefore follows that if you throttle back sufficiently on an O360
> you should get the same range as an O320. Is this true. I flew
> recently with a friend in his RV7A (O360 and FP Sensenich). At
8000'
> I was amazed to note the fuel burn was only 20 litres/hour when he
> dropped the revs back to about 2000....and we were still doing 130
> kts. I got a bit excited about that.
>
> But there are two doubts I have in my mind on this issue.
>
> Firstly, given equal power output the O360 will always have to be
at
> a lesser percentage of total power than an O320. This means that
the
> carburettor butterfly valve will be more closed forcing the engine
> to work that little bit harder to suck in air (not as efficient).
Is
> this true. Is this really relevant to range in any meaningful
> sense.I am told that Lycoming engines perform most efficiently at
> about 8000' because that's when the engine produces cruise power at
> full throttle (no air restriction).
>
> Secondly, is it a problem to fly an O360 for long periods at a
quite
> low percentage of total power. Is there any bottom line...except of
> course for the run-in period.
>
> I realise of course that an O360 weighs a bit more than an O320 so
> it has to haul its own weight...but that should be relatively
> insignificant in terms of range.
>
> I'd like to have the O360 for when I need the power, but I'd like
to
> think that I can have the fuel efficiency of an O320 when I
throttle
> the O360 back........Am I living in a fuels paradise?
Online help on this group at:
http://help.yahoo.com/help/groups/
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[Non-text portions of this message have been removed]
Author: "Jon Baker" <jon@...> Time: Mon Mar 22, 2004 6:15 pm PST Link
If you're planning on using the Sensenich, you could probably match
an O-320's fuel burn with an O-360, given enough discipline. But if
you're thinking about using a C/S prop, there may be an RPM
restriction on the O-360 that would keep you from running it that
low. I don't know that for a fact -- it's just something to check
into.
The other thing I would worry about, running it that low for long
periods over water, would be carb ice. I've personally never heard
of anyone experiencing carb ice in an RV. But I've also never known
anyone who wanted to run at 2000 RPM for hours at a time. Be sure
you get a real carb heat muff instead of that little pipe Vans sells.
--- In vansairforce@yahoogroups.com, "bobbarrow747" <bobbarrow@o...>
wrote:
> I'm procratinating about a Lyc O320 vs O360 for my RV7A. I need to
> be able to get good range for some long over water trips I intend
to
> make. People tell me that power output is purely a function of fuel
> burn regardless of engine capacity. On that basis an O360 at the
> same fuel burn as an O320 should produce the same horsepower. It
> therefore follows that if you throttle back sufficiently on an O360
> you should get the same range as an O320. Is this true. I flew
> recently with a friend in his RV7A (O360 and FP Sensenich). At
8000'
> I was amazed to note the fuel burn was only 20 litres/hour when he
> dropped the revs back to about 2000....and we were still doing 130
> kts. I got a bit excited about that.
>
> But there are two doubts I have in my mind on this issue.
>
> Firstly, given equal power output the O360 will always have to be
at
> a lesser percentage of total power than an O320. This means that
the
> carburettor butterfly valve will be more closed forcing the engine
> to work that little bit harder to suck in air (not as efficient).
Is
> this true. Is this really relevant to range in any meaningful
> sense.I am told that Lycoming engines perform most efficiently at
> about 8000' because that's when the engine produces cruise power at
> full throttle (no air restriction).
>
> Secondly, is it a problem to fly an O360 for long periods at a
quite
> low percentage of total power. Is there any bottom line...except of
> course for the run-in period.
>
> I realise of course that an O360 weighs a bit more than an O320 so
> it has to haul its own weight...but that should be relatively
> insignificant in terms of range.
>
> I'd like to have the O360 for when I need the power, but I'd like
to
> think that I can have the fuel efficiency of an O320 when I
throttle
> the O360 back........Am I living in a fuels paradise?
Author: Ron Lee <ronlee@...> Time: Mon Mar 22, 2004 6:16 pm PST Link
Match the O-320 fuel consumption? Bah humbug. When you have power
you use it. Based on what I have seen in this thread I stand by my assertion
that the original poster should go 180 HP minimum and throttle back if needed
for fuel economy, make sure drag is reduced and if really needed install
fuel augmentation system(s).
No way would I give up my 180 HP for a 150 HP engine. Tim Allen would agree.
Ron Lee
>I've heard from some 0-360 users that it is the "self-discipline" of
>running at only 55% that is the problem with fuel conservation to match
>the 0-320 fuel usage.
>
>When you have the extra ponies, you tend to use them and thus the fuel
>savings disappear. :-).
>
>Your "mileage" may vary (pun intended),
>
>Jack Lockamy #71103
>RV-7A 0-320 slider
>still under construction
> ----- Original Message -----
> From: midniteoyl2
> To: vansairforce@yahoogroups.com
> Sent: Monday, March 22, 2004 2:07 PM
> Subject: [VAF Mailing List] Re: Living in a fuel's paradise
> Seems to me that running at 55% on a 360 wouldnt hurt it at all...
> and be about the same as 65% on a 320
>
> Jim
> --- In vansairforce@yahoogroups.com, "bobbarrow747" <bobbarrow@o...>
> wrote:
> > I'm procratinating about a Lyc O320 vs O360 for my RV7A. I need to
> > be able to get good range for some long over water trips I intend
> to
> > make. People tell me that power output is purely a function of fuel
> > burn regardless of engine capacity. On that basis an O360 at the
> > same fuel burn as an O320 should produce the same horsepower. It
> > therefore follows that if you throttle back sufficiently on an O360
> > you should get the same range as an O320. Is this true. I flew
> > recently with a friend in his RV7A (O360 and FP Sensenich). At
> 8000'
> > I was amazed to note the fuel burn was only 20 litres/hour when he
> > dropped the revs back to about 2000....and we were still doing 130
> > kts. I got a bit excited about that.
> >
> > But there are two doubts I have in my mind on this issue.
> >
> > Firstly, given equal power output the O360 will always have to be
> at
> > a lesser percentage of total power than an O320. This means that
> the
> > carburettor butterfly valve will be more closed forcing the engine
> > to work that little bit harder to suck in air (not as efficient).
> Is
> > this true. Is this really relevant to range in any meaningful
> > sense.I am told that Lycoming engines perform most efficiently at
> > about 8000' because that's when the engine produces cruise power at
> > full throttle (no air restriction).
> >
> > Secondly, is it a problem to fly an O360 for long periods at a
> quite
> > low percentage of total power. Is there any bottom line...except of
> > course for the run-in period.
> >
> > I realise of course that an O360 weighs a bit more than an O320 so
> > it has to haul its own weight...but that should be relatively
> > insignificant in terms of range.
> >
> > I'd like to have the O360 for when I need the power, but I'd like
> to
> > think that I can have the fuel efficiency of an O320 when I
> throttle
> > the O360 back........Am I living in a fuels paradise?
> Online help on this group at:
> http://help.yahoo.com/help/groups/
>------------------------------------------------------------------------------
> Yahoo! Groups Links
>
> a.. To visit your group on the web, go to:
> http://groups.yahoo.com/group/vansairforce/
>
> b.. To unsubscribe from this group, send an email to:
> vansairforce-unsubscribe@yahoogroups.com
>
> c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
>[Non-text portions of this message have been removed]
>Online help on this group at:
>http://help.yahoo.com/help/groups/
>
>Yahoo! Groups Links
Author: "Jack Lockamy" <jacklockamy@...> Time: Tue Mar 23, 2004 3:25 am PST Link
Ron,
Im sure you aware that not all 0-320s are rated at 150 HP..... I think the 160 HP version of the 0-320 in RV aircraft is the norm. :-)
According to Van's published specs and those flying with the 160 HP 0-320s, cruise speeds are only reduced about 5 MPH when using the 0-320 vs the 0-360 (180 HP).
185 MPH at 8-8.5 GPH..... good enough for me! :-)
Jack
RV-7A
0-320 160 HP
----- Original Message -----
From: Ron Lee
To: vansairforce@yahoogroups.com
Sent: Monday, March 22, 2004 5:53 PM
Subject: Re: [VAF Mailing List] Re: Living in a fuel's paradise
Match the O-320 fuel consumption? Bah humbug. When you have power
you use it. Based on what I have seen in this thread I stand by my assertion
that the original poster should go 180 HP minimum and throttle back if needed
for fuel economy, make sure drag is reduced and if really needed install
fuel augmentation system(s).
No way would I give up my 180 HP for a 150 HP engine. Tim Allen would agree.
Ron Lee
>I've heard from some 0-360 users that it is the "self-discipline" of
>running at only 55% that is the problem with fuel conservation to match
>the 0-320 fuel usage.
>
>When you have the extra ponies, you tend to use them and thus the fuel
>savings disappear. :-).
>
>Your "mileage" may vary (pun intended),
>
>Jack Lockamy #71103
>RV-7A 0-320 slider
>still under construction
> ----- Original Message -----
> From: midniteoyl2
> To: vansairforce@yahoogroups.com
> Sent: Monday, March 22, 2004 2:07 PM
> Subject: [VAF Mailing List] Re: Living in a fuel's paradise
> Seems to me that running at 55% on a 360 wouldnt hurt it at all...
> and be about the same as 65% on a 320
>
> Jim
> --- In vansairforce@yahoogroups.com, "bobbarrow747" <bobbarrow@o...>
> wrote:
> > I'm procratinating about a Lyc O320 vs O360 for my RV7A. I need to
> > be able to get good range for some long over water trips I intend
> to
> > make. People tell me that power output is purely a function of fuel
> > burn regardless of engine capacity. On that basis an O360 at the
> > same fuel burn as an O320 should produce the same horsepower. It
> > therefore follows that if you throttle back sufficiently on an O360
> > you should get the same range as an O320. Is this true. I flew
> > recently with a friend in his RV7A (O360 and FP Sensenich). At
> 8000'
> > I was amazed to note the fuel burn was only 20 litres/hour when he
> > dropped the revs back to about 2000....and we were still doing 130
> > kts. I got a bit excited about that.
> >
> > But there are two doubts I have in my mind on this issue.
> >
> > Firstly, given equal power output the O360 will always have to be
> at
> > a lesser percentage of total power than an O320. This means that
> the
> > carburettor butterfly valve will be more closed forcing the engine
> > to work that little bit harder to suck in air (not as efficient).
> Is
> > this true. Is this really relevant to range in any meaningful
> > sense.I am told that Lycoming engines perform most efficiently at
> > about 8000' because that's when the engine produces cruise power at
> > full throttle (no air restriction).
> >
> > Secondly, is it a problem to fly an O360 for long periods at a
> quite
> > low percentage of total power. Is there any bottom line...except of
> > course for the run-in period.
> >
> > I realise of course that an O360 weighs a bit more than an O320 so
> > it has to haul its own weight...but that should be relatively
> > insignificant in terms of range.
> >
> > I'd like to have the O360 for when I need the power, but I'd like
> to
> > think that I can have the fuel efficiency of an O320 when I
> throttle
> > the O360 back........Am I living in a fuels paradise?
> Online help on this group at:
> http://help.yahoo.com/help/groups/
>------------------------------------------------------------------------------
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>
> a.. To visit your group on the web, go to:
> http://groups.yahoo.com/group/vansairforce/
>
> b.. To unsubscribe from this group, send an email to:
> vansairforce-unsubscribe@yahoogroups.com
>
> c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
>[Non-text portions of this message have been removed]
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>
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[Non-text portions of this message have been removed]
Author: "midniteoyl2" <midniteoyl@...> Time: Tue Mar 23, 2004 3:25 am PST Link
Seems to me that he wants the extra power a 360 affords for the most
part - but also wants to be able to do long hauls over water when
needed. If he gets a 320, he prolly will be kicking himself
everytime he takes off or needs to climb fast...
Get the 360 and just throttle back when needed. No worries..
Jim
--- In vansairforce@yahoogroups.com, Ron Lee <ronlee@p...> wrote:
> Match the O-320 fuel consumption? Bah humbug. When you have
power
> you use it. Based on what I have seen in this thread I stand by
my assertion
> that the original poster should go 180 HP minimum and throttle
back if needed
> for fuel economy, make sure drag is reduced and if really needed
install
> fuel augmentation system(s).
>
> No way would I give up my 180 HP for a 150 HP engine. Tim Allen
would agree.
>
> Ron Lee
> >I've heard from some 0-360 users that it is the "self-discipline"
of
> >running at only 55% that is the problem with fuel conservation to
match
> >the 0-320 fuel usage.
> >
> >When you have the extra ponies, you tend to use them and thus the
fuel
> >savings disappear. :-).
> >
> >Your "mileage" may vary (pun intended),
> >
> >Jack Lockamy #71103
> >RV-7A 0-320 slider
> >still under construction
> > ----- Original Message -----
> > From: midniteoyl2
> > To: vansairforce@yahoogroups.com
> > Sent: Monday, March 22, 2004 2:07 PM
> > Subject: [VAF Mailing List] Re: Living in a fuel's paradise
> > Seems to me that running at 55% on a 360 wouldnt hurt it at
all...
> > and be about the same as 65% on a 320
> >
> > Jim
> > --- In vansairforce@yahoogroups.com, "bobbarrow747"
<bobbarrow@o...>
> > wrote:
> > > I'm procratinating about a Lyc O320 vs O360 for my RV7A. I
need to
> > > be able to get good range for some long over water trips I
intend
> > to
> > > make. People tell me that power output is purely a function
of fuel
> > > burn regardless of engine capacity. On that basis an O360 at
the
> > > same fuel burn as an O320 should produce the same
horsepower. It
> > > therefore follows that if you throttle back sufficiently on
an O360
> > > you should get the same range as an O320. Is this true. I
flew
> > > recently with a friend in his RV7A (O360 and FP Sensenich).
At
> > 8000'
> > > I was amazed to note the fuel burn was only 20 litres/hour
when he
> > > dropped the revs back to about 2000....and we were still
doing 130
> > > kts. I got a bit excited about that.
> > >
> > > But there are two doubts I have in my mind on this issue.
> > >
> > > Firstly, given equal power output the O360 will always have
to be
> > at
> > > a lesser percentage of total power than an O320. This means
that
> > the
> > > carburettor butterfly valve will be more closed forcing the
engine
> > > to work that little bit harder to suck in air (not as
efficient).
> > Is
> > > this true. Is this really relevant to range in any meaningful
> > > sense.I am told that Lycoming engines perform most
efficiently at
> > > about 8000' because that's when the engine produces cruise
power at
> > > full throttle (no air restriction).
> > >
> > > Secondly, is it a problem to fly an O360 for long periods at
a
> > quite
> > > low percentage of total power. Is there any bottom
line...except of
> > > course for the run-in period.
> > >
> > > I realise of course that an O360 weighs a bit more than an
O320 so
> > > it has to haul its own weight...but that should be relatively
> > > insignificant in terms of range.
> > >
> > > I'd like to have the O360 for when I need the power, but I'd
like
> > to
> > > think that I can have the fuel efficiency of an O320 when I
> > throttle
> > > the O360 back........Am I living in a fuels paradise?
> > Online help on this group at:
> > http://help.yahoo.com/help/groups/
> >------------------------------------------------------------------
------------
> > Yahoo! Groups Links
> >
> > a.. To visit your group on the web, go to:
> > http://groups.yahoo.com/group/vansairforce/
> >
> > b.. To unsubscribe from this group, send an email to:
> > vansairforce-unsubscribe@yahoogroups.com
> >
> > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
of Service.
> >[Non-text portions of this message have been removed]
> >Online help on this group at:
> >http://help.yahoo.com/help/groups/
> >
> >Yahoo! Groups Links
Author: "midniteoyl2" <midniteoyl@...> Time: Tue Mar 23, 2004 3:26 am PST Link
Opps... need to actually read before replying ...
Ya... What Ron Lee said <grinz>
Jim
--- In vansairforce@yahoogroups.com, Ron Lee <ronlee@p...> wrote:
> Match the O-320 fuel consumption? Bah humbug. When you have
power
> you use it. Based on what I have seen in this thread I stand by
my assertion
> that the original poster should go 180 HP minimum and throttle
back if needed
> for fuel economy, make sure drag is reduced and if really needed
install
> fuel augmentation system(s).
>
> No way would I give up my 180 HP for a 150 HP engine. Tim Allen
would agree.
>
> Ron Lee
> >I've heard from some 0-360 users that it is the "self-discipline"
of
> >running at only 55% that is the problem with fuel conservation to
match
> >the 0-320 fuel usage.
> >
> >When you have the extra ponies, you tend to use them and thus the
fuel
> >savings disappear. :-).
> >
> >Your "mileage" may vary (pun intended),
> >
> >Jack Lockamy #71103
> >RV-7A 0-320 slider
> >still under construction
> > ----- Original Message -----
> > From: midniteoyl2
> > To: vansairforce@yahoogroups.com
> > Sent: Monday, March 22, 2004 2:07 PM
> > Subject: [VAF Mailing List] Re: Living in a fuel's paradise
> > Seems to me that running at 55% on a 360 wouldnt hurt it at
all...
> > and be about the same as 65% on a 320
> >
> > Jim
> > --- In vansairforce@yahoogroups.com, "bobbarrow747"
<bobbarrow@o...>
> > wrote:
> > > I'm procratinating about a Lyc O320 vs O360 for my RV7A. I
need to
> > > be able to get good range for some long over water trips I
intend
> > to
> > > make. People tell me that power output is purely a function
of fuel
> > > burn regardless of engine capacity. On that basis an O360 at
the
> > > same fuel burn as an O320 should produce the same
horsepower. It
> > > therefore follows that if you throttle back sufficiently on
an O360
> > > you should get the same range as an O320. Is this true. I
flew
> > > recently with a friend in his RV7A (O360 and FP Sensenich).
At
> > 8000'
> > > I was amazed to note the fuel burn was only 20 litres/hour
when he
> > > dropped the revs back to about 2000....and we were still
doing 130
> > > kts. I got a bit excited about that.
> > >
> > > But there are two doubts I have in my mind on this issue.
> > >
> > > Firstly, given equal power output the O360 will always have
to be
> > at
> > > a lesser percentage of total power than an O320. This means
that
> > the
> > > carburettor butterfly valve will be more closed forcing the
engine
> > > to work that little bit harder to suck in air (not as
efficient).
> > Is
> > > this true. Is this really relevant to range in any meaningful
> > > sense.I am told that Lycoming engines perform most
efficiently at
> > > about 8000' because that's when the engine produces cruise
power at
> > > full throttle (no air restriction).
> > >
> > > Secondly, is it a problem to fly an O360 for long periods at
a
> > quite
> > > low percentage of total power. Is there any bottom
line...except of
> > > course for the run-in period.
> > >
> > > I realise of course that an O360 weighs a bit more than an
O320 so
> > > it has to haul its own weight...but that should be relatively
> > > insignificant in terms of range.
> > >
> > > I'd like to have the O360 for when I need the power, but I'd
like
> > to
> > > think that I can have the fuel efficiency of an O320 when I
> > throttle
> > > the O360 back........Am I living in a fuels paradise?
> > Online help on this group at:
> > http://help.yahoo.com/help/groups/
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Author: David Brand <dbrandx@...> Time: Tue Mar 23, 2004 3:26 am PST Link
bob....
Which ever engine you choose, if you`re trying to maximize efficiency,
you`ll need fuel injection. That way, you`d be able to run lean of peak
EGT fuel mixture and still opperate relatively smoothly. A carb is just
not able to do this. In the 320 vs 360 debate, both engines share the same
bore dimension, which means the 360 gets it`s additional cubes through
longer stroke. This is good for more torque which computes to more
horsepower, but also higher piston speed, at any given RPM, which means
more internal friction. Whether this increase in friction is enough to
make a difference to your operation is debateable. Personally, I`d go with
a parallel valve IO-360, Lightspeed ignition, and one of the composite C/S
props. I don`t think the difference in weight between a 320 and 360 is
enough to be significant from an efficiency standpoint.
Dave Brand N254LF
--- bobbarrow747 <bobbarrow@...> wrote:
> I'm procratinating about a Lyc O320 vs O360 for my RV7A. I need to
> be able to get good range for some long over water trips I intend to
> make. People tell me that power output is purely a function of fuel
> burn regardless of engine capacity. On that basis an O360 at the
> same fuel burn as an O320 should produce the same horsepower. It
> therefore follows that if you throttle back sufficiently on an O360
> you should get the same range as an O320. Is this true. I flew
> recently with a friend in his RV7A (O360 and FP Sensenich). At 8000'
> I was amazed to note the fuel burn was only 20 litres/hour when he
> dropped the revs back to about 2000....and we were still doing 130
> kts. I got a bit excited about that.
>
> But there are two doubts I have in my mind on this issue.
>
> Firstly, given equal power output the O360 will always have to be at
> a lesser percentage of total power than an O320. This means that the
> carburettor butterfly valve will be more closed forcing the engine
> to work that little bit harder to suck in air (not as efficient). Is
> this true. Is this really relevant to range in any meaningful
> sense.I am told that Lycoming engines perform most efficiently at
> about 8000' because that's when the engine produces cruise power at
> full throttle (no air restriction).
>
> Secondly, is it a problem to fly an O360 for long periods at a quite
> low percentage of total power. Is there any bottom line...except of
> course for the run-in period.
>
> I realise of course that an O360 weighs a bit more than an O320 so
> it has to haul its own weight...but that should be relatively
> insignificant in terms of range.
>
> I'd like to have the O360 for when I need the power, but I'd like to
> think that I can have the fuel efficiency of an O320 when I throttle
> the O360 back........Am I living in a fuels paradise?
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Author: "dimplemaster" <johnsiebold@...> Time: Tue Mar 23, 2004 8:03 am PST Link
Bob,
Consider a 320 with 10:1 pistons, injection, flow matching, electronic ignition,
Superior sump, and a few other tricks that Lycon knows. Several versions hereabouts
dyno well in excess of 200 hp. Stick on a Whirlwind 200RV, and you have a relatively
light, powerful, and efficient drive train. True experimentation.
' course, you could do the same thing with a 360. Beyond efficiency and sucking up
useful load (I'm an engineer and mull such matters, also), what's the concern with fuel
economy all about? The difference in consumption as a percentage of operational
costs is tiny. If you're going for range, add tanks and a large bladder.
For my bucks, go for the big horsepower in a standard, easy-to-live-with package.
I've never run across anyone who disdains horsepower once they have it, but
maintenance follys with a tricked out mill could get tiring.
John Siebold
Baffling a 7
Author: Ken Harrill <kharrill@...> Time: Tue Mar 23, 2004 9:40 am PST Link
-----Original Message-----
From: David Brand [mailto:dbrandx@...]
bob....
Which ever engine you choose, if you`re trying to maximize efficiency,
you`ll need fuel injection. That way, you`d be able to run lean of peak
EGT fuel mixture and still opperate relatively smoothly. A carb is just
not able to do this.
Dave and Bob,
I have an O-360 with Superior sump, lightspeed ignition and C/S prop. At
less that 65% power I run lean of peak and get some impressively low fuel
burns. My guess is that the engine runs smoothly because of the EI and the
Superior sump. My EGT's and CHT's run very close between cylinders. I
don't do this above 65% power.
At 60% or so I can fly along with my friends in Mooney's and Bonanza's(:
Ken Harrill
RV-6
Columbia, SC
Author: "Randy Lervold" <randy@...> Time: Tue Mar 23, 2004 9:40 am PST Link
That's almost exactly what I'm planning for my RV-3B except for using the WW 151 instead due to it's lighter weight.
Randy Lervold
www.romeolima.com/RV3factory.htm
----- Original Message -----
From: dimplemaster
To: vansairforce@yahoogroups.com
Sent: Tuesday, March 23, 2004 7:48 AM
Subject: [VAF Mailing List] Re: Living in a fuel's paradise
Bob,
Consider a 320 with 10:1 pistons, injection, flow matching, electronic ignition,
Superior sump, and a few other tricks that Lycon knows. Several versions hereabouts
dyno well in excess of 200 hp. Stick on a Whirlwind 200RV, and you have a relatively
light, powerful, and efficient drive train. True experimentation.
' course, you could do the same thing with a 360. Beyond efficiency and sucking up
useful load (I'm an engineer and mull such matters, also), what's the concern with fuel
economy all about? The difference in consumption as a percentage of operational
costs is tiny. If you're going for range, add tanks and a large bladder.
For my bucks, go for the big horsepower in a standard, easy-to-live-with package.
I've never run across anyone who disdains horsepower once they have it, but
maintenance follys with a tricked out mill could get tiring.
John Siebold
Baffling a 7
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[Non-text portions of this message have been removed]
Author: "lindbergs52" <lindbergs1@...> Time: Wed Mar 24, 2004 3:23 am PST Link
Anybody running a Superior oil sump made of Ryton? Anything to
report to the group? Steve
--- In vansairforce@yahoogroups.com, "dimplemaster"
<johnsiebold@a...> wrote:
> Bob,
>
> Consider a 320 with 10:1 pistons, injection, flow matching,
electronic ignition,
> Superior sump, and a few other tricks that Lycon knows.