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Performance benchmarking

Bsquared

Well Known Member
I have about 140 hrs on my 14A with the 210 hp 390. I tried a number of power and mixture settings and have settled in with what is shown on this pic from a recent x-country flight. 2400 rpm, WOT and 60 LOP at 9800 ft density altitude results in 165 kts TAS and 8.8 GPH. I can get the FF down to 8.2 GPH by reducing the power down to the 52% range but the drop in TAS doesn’t seem to make it worthwhile. For other operators of the 210 hp engine is this what you see from your airplane?
 

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Similar Results

Today I tried to match your parameters and the results are nearly identical to yours. I have 155 hours on my RV-14A as of today's flight. I flew at 8500ft with WOT and 8.8 gal/hr FF. My density altitude was a little less than yours because my OAT was 5 degrees cooler but, otherwise, the results appear to be very similar.

EDIT: I did the calc and, actually, our density altitudes were within a few feet of each other. It's pretty amazing to me how close our performance numbers are. BTW, my engine is also the 210 HP IO-390. Mine is a Thunderbolt, but that doesn't appear to matter!
 

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95 hrs on a RV-14 taildragger with a 390 Thunderbolt.
 

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167 true for the same 2400 WOT LOP profile. Further, I note that my CHTs are similar to the posters. #2 cylinder is hottest by 20 degrees or so, and 3 and 4 are the coolest. Weird.

Warning: Thread drift…. BTW, #2 had morning sickness fixed by reaming and cleaning out black gunk out of the valve guide and off the stem. Temperature issue?

Search for “Sticky Valve” in this subforum for more info.
 
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I am running one emag & one conventional. Emag is stock set up timed at 4 degrees past TDC.
 
I am also running one emag & one conventional. Emag is set to A curve and timed at 6ish degrees past TDC.
 
One Emag and one conventional as well for me (original Poster). Emag using the A curve and timed to 5 deg ATDC.
 
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Cross country numbers

Additional data points. Mine is a tail dragger, T-bolt IO-390 with dual P-Mags timed at 5-deg PTDC (A-curve). About 30-50 LOP and WOT. Density altitudes 8,461, 10,581, and 11,508 density altitudes respectively.

Headwind was crushing me on the first two. Next day…mostly crosswind. Life’s not fair!!

(Disregard my aileron trim - the gauge really exaggerates the trim amount. My plane is straight…I swear.)

Seems like I’m in the general ballpark with others.
 

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So far it looks like the results are pretty consistent, with the tail draggers being a bit more efficient/faster. The Vans RV-14 brochure doesn’t list Fuel Flow directly for comparison but the published speeds seem to be in line with real world numbers.

I think part of this is because the 14 kit and instructions are so detailed and complete regarding things like wheel pants and intersection fairings. An all around great airplane!
 
My 14A results with dual conventional mags yield same speed results but with about a gallon an hour increase in fuel burn.
 
Here's some RV-14A performance data I collected a few days ago. I have unfiltered RAM air induction or through a snorkel/filter combination. The outside air temp that day was 54F, so ~ 10,000 ft density altitude.
 

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Hi Marty,

Can you share some photos of your Ram vs filtered setup? I looked at your builder log but was not able to find details.

Thanks
 
I'll try to take some better pics when I do my condition inspection, but here are a few...
 

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Very interesting.

Did you make the ram air appliance?

I assume there is a control for switching back and forth, yes?

Did you make any other adjustments - injectors, timing, exhaust etc to accommodate filtered vs ram air?

Thanks for sharing.
 
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EXP

Hi
I have the EXP Version. Dual P-Mag. This is our economy setting.
28 liters per hour usually, that corresponds to 7.3 USG…

Fabian
 

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The Vans RV-14 brochure doesn’t list Fuel Flow directly for comparison but the published speeds seem to be in line with real world numbers.

I have quite a bit of flight time in our 14A in its prior configuration (before being upgraded to the EXP119 engine) and with the standard air induction system with the square filter it consistently had TAS's of 171 kts at around 8.2 GPH, at DA's of 10.5-11.5.
 
I have quite a bit of flight time in our 14A in its prior configuration (before being upgraded to the EXP119 engine) and with the standard air induction system with the square filter it consistently had TAS's of 171 kts at around 8.2 GPH, at DA's of 10.5-11.5.

That's pretty good fuel burn for the speed.
 
I have quite a bit of flight time in our 14A in its prior configuration (before being upgraded to the EXP119 engine) and with the standard air induction system with the square filter it consistently had TAS's of 171 kts at around 8.2 GPH, at DA's of 10.5-11.5.

I can get close to those numbers above 12,500 DA but not quite. Maybe the hail dents in the factory airplane give it a speed advantage. ��
 
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Very interesting.

Did you make the ram air appliance?

I assume there is a control for switching back and forth, yes?

Did you make any other adjustments - injectors, timing, exhaust etc to accommodate filtered vs ram air?

Thanks for sharing.

I purchased the double-butterfly Y-valve from Airflow Performance and the hose adapter to the filter off Amazon. I used an Airflow Performance bracket to run the controls under the engine and ran the air control cable to the panel. The induction scoop is also something I built. I did all this to make room for the A/C compressor where the standard snorkel normally goes, but was also motivated by the ability to achieve higher MP using RAM air. I can get quite close to the same results Scott reports (171 kts at 2300 rpm/23 in, 7500 ft MSL) but at a slightly higher fuel flow (9.2 gph). I'm about 100 lbs heaver with the A/C installed and the induction scoop probably increases the drag slightly.
 
Don't put too much weight on the difference between Marty's filtered and unfiltered performance.

The filtered system is crippled, taking its air from inside the lower cowl volume. That volume has already suffered a large pressure drop across the engine cooling fins. It is being fed with little more than freestream pressure, unlike the standard snorkel filter, which is at freestream plus 70 to 80% of the available dynamic pressure (q).

In addition, the filter is in the cooling air outflow from #2, which is quite hot, so air density is low....effectively the same as a big jump in density altitude, and pro-detonation too.
 
Dan,
I don’t know who you are and don’t know why you think you are an authority on my set-up. I chose this route after much discussion with known experts, and after 200 hrs have had very satisfactory performance. Out of respect, I would appreciate it if you would direct any comments to my post directly to me and I would be glad to answer any questions you have about my airplane. This forum is a platform for sharing learnings and ideas and not to discredit another user. If you can’t do that, I would prefer you didn’t comment further on a post of mine.
 
Sorry to hear you're unhappy Marty. Instrument the installation for temperature and pressure and you'll find the commentary is accurate. Taking intake air from a hot place stripped of dynamic pressure results in reduced performance. The HP loss here is 8.4%. It's just the facts.

It is entirely possible to build a full time filtered system with very small pressure loss, or a Y-system offering choice of unfiltered ram or filtered air...with the filtered air being supplied from a cool, high pressure location.

https://vansairforce.net/community/showthread.php?t=175589

https://vansairforce.net/community/showthread.php?t=49556
Steve's photos here:
http://www.hpaircraft.net/rv8/100_1801a.jpg
http://hpaircraft.net/rv8/p1010163b.jpg

Chris Zavatson's work:
http://www.n91cz.net/airbox/airbox.htm
 
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