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  #1  
Old 10-19-2021, 06:00 PM
jigeye jigeye is offline
 
Join Date: Oct 2021
Location: Memphis TN
Posts: 2
Default RV-7 and IO-390 perforance gains

I have seen a few with this engine. what do gain in performance vs. a IO-360? Would like some real world #s. thanks.
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  #2  
Old 10-19-2021, 09:50 PM
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rswalden rswalden is offline
 
Join Date: Mar 2005
Posts: 150
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Quote:
Originally Posted by jigeye View Post
I have seen a few with this engine. what do gain in performance vs. a IO-360? Would like some real world #s. thanks.
After 1000 hours on my IO-390 I have only good things to say. Oil consumption is almost nil, climb performance is awesome, and fuel economy excellent... I flightplan for 165TAS with 74" Hartzell constant speed prop... Fuel flow around 8gph at altitude (wide open throttle)...

To be fair, however, I think RV's are optimized for 180 hp. In level flight cruise with other RV's... the -390 doesn't buy you much performance over a -360 due to airfoil design & drag.

The big payoff, in my opinion, is short field takeoff & climb performance.... making it ideal for high pressure altitude operations...
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Bob Walden (Waldo), CFII-ASMEL, Commercial Glider
KFFC "Falcon RV Squadron" Peachtree City, GA
RV-7A Tip-Up, IO-390, 1000+ Hours
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  #3  
Old 10-19-2021, 10:22 PM
blaplante blaplante is offline
 
Join Date: Jan 2010
Location: Southern California
Posts: 352
Default

baseline --- which io-360? 180 HP or 200 HP?

I think your best 'real world' estimate is the factory performance specs at https://www.vansaircraft.com/rv-7/#aircraft-details-2

which shows going from 180 HP to 200 HP is worth 7 mph in cruise. Or +3.5%

So making an educated estimate - going from 200 HP to 210 is going to give you 3 mph or so added cruise speed.
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  #4  
Old 10-22-2021, 12:43 PM
riobison riobison is offline
 
Join Date: Jul 2011
Location: Oliver BC & Red Deer Alberta Canada
Posts: 414
Default ROC

what is the real world ROC with the 210 HP?
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  #5  
Old 10-22-2021, 02:05 PM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 10,361
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Simplified speed and ROC equations at the link. Baseline depends on which IO-360, 180 hp parallel valve, or 195 hp for an average angle valve. If comparing parallel valve to the 390, the ROC increase may be a little less than indicated, as the simple equation assumes equal weight.

www.danhorton.net/Articles/
then download "Speaking Truth To Power"
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Last edited by DanH : 10-22-2021 at 02:08 PM.
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  #6  
Old 10-22-2021, 04:02 PM
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Rick_A Rick_A is offline
 
Join Date: Oct 2005
Location: Jacksonville, FL
Posts: 1,572
Default Consider an IO 370

I replaced my 180hp O360 with a Titan IO-370. It's officially rated at 195 hp but un-official number is something in the 200-210 range. It weighs the same or a bit less than an IO-360 (I have the tapered cylinders).

I don't have exact numbers but I could tell immediately that is was a noticeable improvement. I gained at least 7kts in cruise and a big improvement in my climb. My rate of climb is limited by my nose up attitude and once I get to about 800 ft, I want to reduce my climb angle so I can watch for traffic in front of me.
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  #7  
Old 10-22-2021, 05:55 PM
tgmillso tgmillso is offline
 
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 841
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Keep in mind that going to the IO-390 may reduce the ability to use mogas or other UL fuels, unless you get it custom built with a lower CR, in which case you will be giving up some of the performance benefits. Also keep in mind that the 390 will be heavier than a comparable 360, and every kg extra in engine is a kg lost in fuel or payload. You may be able to offset this my swinging a composite prop, so take this into account in your w&b and budgeting.
Not that any of this should concern me, as my next build is going to be all electric. Let’s just hope Lyten or some of their competitors with 500+ Wh/kg energy density can get to production sooner than later.
Tom.
RV-7, IO-360M1B
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  #8  
Old 10-22-2021, 07:40 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 927
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Quote:
Originally Posted by rswalden View Post
After 1000 hours on my IO-390 I have only good things to say. Oil consumption is almost nil, climb performance is awesome, and fuel economy excellent... I flightplan for 165TAS with 74" Hartzell constant speed prop... Fuel flow around 8gph at altitude (wide open throttle)...

To be fair, however, I think RV's are optimized for 180 hp. In level flight cruise with other RV's... the -390 doesn't buy you much performance over a -360 due to airfoil design & drag.

The big payoff, in my opinion, is short field takeoff & climb performance.... making it ideal for high pressure altitude operations...
I’m curious about your setup.. my fixed pitch Sensenich aluminum prop and O-360 with slick mags does 170 knots in cruise at 7gph. I would expect a little more speed with your setup over my -4. Granted, the -4 is a making a smaller hole being tandem.. what altitude are you flying? I guess these plane really just can’t push the airfoil much past the 170 mark, but I bet yours climbs like a homesick angel!
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Las Vegas
RV-4 flying…
RV-8 empenage finished 10-2020

Wings Started.. 11-2020
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  #9  
Old 10-22-2021, 09:15 PM
riobison riobison is offline
 
Join Date: Jul 2011
Location: Oliver BC & Red Deer Alberta Canada
Posts: 414
Default Speed

My 4 with an O 360, mags and a woody prop at 8000 ft DA and 2650+ RPM is pulling 208 mph with the new PR wheel pants. The original wheel pants I was only 201 mph.

I didn't think that there was that much of a difference between the different models.

Tim
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  #10  
Old 10-23-2021, 03:53 AM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 927
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Quote:
Originally Posted by riobison View Post
My 4 with an O 360, mags and a woody prop at 8000 ft DA and 2650+ RPM is pulling 208 mph with the new PR wheel pants. The original wheel pants I was only 201 mph.

I didn't think that there was that much of a difference between the different models.

Tim
Wow, that’s 181 knots.. that’s smoking!
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RV-8 empenage finished 10-2020

Wings Started.. 11-2020
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