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IO-390 or IO-390EXP119

Michael Burbidge

Well Known Member
My RV-14A build will be a basic VFR equipped airplane. I'm trying to be frugal where I can. I figure the cost difference to go with the IO-390EXP119 is about $4000.

I've about concluded to go with the IO-390 A3B6 as part of my goal to be frugal where I can.

What think ye? Is anyone else making this same choice?

Thanks,
Michael-
 
The main advantages as I understand it for the EXP 119 version are 5 more rated HP, lower weight, and pre-installed Airflow Performance fuel injection system.

The biggest / most significant disadvantage of the EXP 119 (other than price) is that there is no accessory drive (intended on older version for vacuum pump) that can be used for a backup alternator.

Disadvantage of the standard version is the need to modify the snorkel and cable routing (mixture/throttle) if you add Airflow Performance fuel injection (a pain but manageable).

So if you don't mind 5 less HP and don't mind the standard fuel injection (or don't mind modifying the snorkel if you go with Airflow) the standard version is a good option.
 
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Worth it ?

There's a very good engineer/builder who wanted to explore the direct difference, so he spent a lot of time/$$$ to convert. I applaud him for the effort. He thoroughly documented the process. Perhaps someone has a link. This way it was an apples-to-apples comparison. Same prop, same airframe, etc. except he modified the engine and cowling.
 
A lot of people say EXP-119 and Thunderbolt all in the same breath, but they’re two separate things.

With the EXP-119 you primarily get the cold-air induction, the larger 200 mm airflow performance throttle body, and the option to delete the vacuum pump accessory pad….which I think is a bad idea. It takes away the ability to add a backup alternator.

With the Thunderbolt your engine is lovingly built by a one or two man team that takes special care during assembly. The engine is ported, polished, and balanced…it’s basically blueprinted. You can also choose the compression ratio (8.9 or 10:1) You also have your choice of ignition systems. I’m not one hundred percent sure, but I think you can also opt for the larger 200 mm airflow performance fuel injection that comes on the EXP-119. You also have your choice of engine colors.

If you’re planning on the SDS or EFII injection and ignition systems, other than the cold air induction, there’s really no reason to get the EXP-119.

If you decide to go with the “standard” 390….with or without the Thunderbolt treatment, I think you can still order your kit with the EXP-119 cowling and snorkel just as if it were an actual EXP-119. Don’t take my word for it though and confirm this with Vans. I actually don’t know what the differences are in the cowling?? I could be mistaken, but I think all of the kits come with the 4 into 2 exhaust pipes now. If the standard/non EXP-119 cowling is still designed for the 4 into 1 exhaust pipe, then you should be able to opt for the EXP-119 cowling and 4 into 2 exhaust pipe. But once again, you’d need to confirm these things with Vans.

I did a “home-brew” EXP-119. I got the Thunderbolt option, but I’m installing the Superior cold-air induction rather than going with the Lycoming cold air. I also had Clint build my exhaust pipe, which is a trombone design rather than the cross over. This pipe was required with the Superior cold air unit.

When ordering, I ordered everything (the cowling and snorkel) as if I were going with the EXP-119 even though “technically” it’s not.

Saying all of that, and making a long story longer, I’m sure you’ll be perfectly happy with the standard A3B6 and your airplane will still perform well.

Hopefully this will give you a little bit food for thought and help guide you through the maze.
 
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Another point of view

My kit was #140329, ordered in 2016, flying in 2018. The -119 was not an option; only standard or Thunderbolt. I went with the standard because I couldn’t justify the added cost of t-bolt on a 2,700 RPM engine. No regrets! Love my airplane, love the performance.
 
The drag reduction efforts paid off. From Van's:

i-7932Bmf-L.jpg
 
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Kitplanes

I've also read the article in Kitplanes about the IO-390EXP119 upgrade. I believe it is DanH that describes the drag reduction and the math behind it. Good info.

https://www.kitplanes.com/flight-review-vans-rv-14a-with-lycoming-io-390-exp119-engine/

Even given all the positives, I was curious if there were others that were still opting for the vanilla IO-390 because of the cost of the upgrade. It sounds like there are others.

Michael-
 
There's a very good engineer/builder who wanted to explore the direct difference, so he spent a lot of time/$$$ to convert. I applaud him for the effort. He thoroughly documented the process. Perhaps someone has a link. This way it was an apples-to-apples comparison. Same prop, same airframe, etc. except he modified the engine and cowling.

The published 119EXP performance increases were obtained the same way… the original prototype was used while developing all of the modifications so the differences in performance between the standard and the EXP119 versions are well quantified.
 
As DanH has said the bulk of performance gains come from a change in cooling drag flowing through the cowling. I have an A3B6 in a -14 that with the 5 inch oil cooler that IMHO is overcooled. The fixed cowl scoop on the original cowl provides almost 3 times the exit area of the new cowling.

Designing the proper amount of cooling for an aircraft with the speed range of the RV is quite the challenge. It needs to work both in the summer and in the pattern but not give up too much when cruising along at 180 knots. A movable cowl flap is the solution but adds complexity. I ran the control cable when building so this can be added. The -14 doesn't need the fixed scoop for gear or engine clearance so my plan is remove it and replace with a moveable flap. The bottom of the cowling will run flush into the fuse without the bump. I won't do this until I have my -14a flying as I need something to fly and really this project is just chasing pennies left on the ground. I will be sure to post results when I get them. BTW I am installing the standard A3B6 on my 14a as well. I also got the quote for adding the cold air induction to convert A3B6 to EXP119.....$12k from lycoming! No Thanks!
 
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The drag reduction efforts paid off. From Van's:

i-7932Bmf-L.jpg

Interestingly, it appears the 200 hp IO-360 might be the best bang for the buck.

I ordered the EXP119 a little over a year ago. I thought it was the most viable option as it appeared Van's had done a lot of optimization for this engine and it appeared to be the logical choice at the time. Not sure I feel that way now and it is the most costly option.
 
Performance data

It appears the data for the original 390 engine and cowling might be a tad conservative. Using mid-points for power setting (65%) and weight between max and the lower weight in the chart (1,880 lbs. which is more typical for normal cross country flying) I came up with 166 knots for the early 390's and 175 knots for the new 390 and cowling. (Subject to rounding) Using my performance data for my early 390 this seems low. It would be interesting to see what others are getting closer to 65% settings.

Also, would be interesting to hear if others are seeing a difference with and without reflex. (3%) I fly almost the same route every week (Tampa to Jacksonville) and have tried both settings for 15 to 20 minutes each leg and sometimes reflex is slightly better sometimes no reflex slightly better. I've given up making the comparison. I know several RV-10 flyers who have tried the same test and they don't see a difference. The pitch of the airframe changes slightly but not the TAS or GPS ground speed.
 
In my opinion the performance numbers for EXP119 engine are conservative too. I'm a first time builder therefore my RV14 is far from perfect. Installed oversized tires, several external antennas and to make things worst, against mothership recommendations opted for 74" BA Hartzell Prop. Despite it all I can easily exceed the 218 mph top speed.
 
In my opinion the performance numbers for EXP119 engine are conservative too. I'm a first time builder therefore my RV14 is far from perfect. Installed oversized tires, several external antennas and to make things worst, against mothership recommendations opted for 74" BA Hartzell Prop. Despite it all I can easily exceed the 218 mph top speed.

Remember the 218 mph top speed is for a tri-gear RV-14A with the IO-390-EXP119. If you've got an RV-14 taildragger, it is expected that it will be faster than that.
 
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