New RV-4 Owner with Questions

[hman1359]

I am a very new owner of my RV-4, and am loving it. I'm up to almost 30 hours in it, and am starting to think about the long run of ownership, including making some modifications/upgrades, and wanted to get some opinions.

It's an O-320-B2A FP 160hp engine with a 68" wood sterba cruise prop, sam james cowl and short gear.

One of the more annoying things I have experienced is that cylinders 2 and 4 get extremely hot when I am at high power settings. I can rarely run WOT unless I'm way up in the 9-11k range because of CHTs. I find more often than not I have to climb up a thousand feet at a time, and then really pull the power back to allow the cylinders to cool, and I feel like I shouldn't need to do this. I've tried climbing at slower speeds, but it seems anything below 150 mph indicated really heats those cylinders up quickly, and climbing at 150 indicated results in a painfully slow climb speed. Is this normal?

Also, it has seemed that my cruise speeds are rather slow compared to other comparable setups. I can't cruise at much more than 140-145KIAS unless I really push the temps or get RPMs up into the higher 2600s, which doesn't seem to line up with what I have heard other RV-4 owners perform at. Might there be a reason for this?

The next thing I want to do is upgrade the panel. I'm rocking a *very* VFR panel. I am planning on removing the vacuum pump next week, along with the DG and ADI, both of which are inop. I have already ordered the cover and gasket for the vacuum pump. I think eventually I might go with a full glass panel, but for now I'm just looking for an attitude indicator so I can feel comfy night flying. Is a single G5 really as easy to install as it seems?

The last thing that bothers me is the location of my transponder and radio. I have an old Narco AT 150 transponder and a COM 760 TSO radio that hang underneath the main panel and kind of get in the way of my knees while flying. Eventually I'd like to get a better radio that isn't as static-y, but for now I am wondering if they might fit better in a different spot. If I do move them, I assume I'd need to cut a new panel. How difficult is that to do?

Like I said, I'm very new to all of this, and am just exploring my options, so I'm open to any and all feedback. Thanks!

 

[D-Dubya]

First off, welcome to the site! Secondly, wow...that's a lot of questions.

For starters, it's Experimental, so you can make just about any kind of change you want that you feel you can safely make. If something doesn't work for you, change it and make it your own. My two cents would be to make all the panel changes at one time. Piecemealing a couple instruments at a time is a lot of work if you're going to do it over and over, as the configurations for each instrument and how well it plays with the other instruments can take a lot of time. If you're gonna go glass, I'd suggest doing it all at once. But others have done differently as time, skills, and budget permit--and they've made it work. Making a new panel isn't that tough, as you can usually use the old panel as a template outline. Or there are plenty of shops that can design and/or build a panel for you using CAD/CAM systems.

As far as the high CHTs go, how high is high? This is a deep subject and there are lots of threads about it on this forum that you can search. Mike Busch (and others) have done webinars and written articles extensively about this subject. Researching those may be a good start for gaining a better understanding of what affects CHTs and what is in fact "high". You can use the search function on this site, but I've found searching in Google using the following format works better: [site: vansairforce.net high CHT], or putting whatever key phrase you want instead of "high CHT". You don't need the brackets, BTW. But just to get you rolling, I would say the three biggest factors are 1) baffles and sealing, 2) advanced engine timing, and 3) fuel flow.

 

[SMRacer]

I know nothing about the G5, but I have a GRT Mini in my RV8 panel as a backup. I'm essentially only using it as an emergency attitude indicator, but it has other capabilities, including GPS Nav. All in one self contained unit (no remote magnetometer) with only Power/Ground electrical connections, and pitot/static inputs. External GPS antenna.
As far as the CHT problem, I'd start by looking at the cowl baffle on the 2-4 side. Make sure there are no air diverters in the cowl opening.
Upgrading the panel is also not a problem. You can cut it yourself, or hire out one of the panel designer/cutters. The design of the RV4 leaves very easy access to the rear of the panel for smaller upgrades. Check your airspeed indicator against another aircraft or GPS pattern flying. Insure that it is accurate before you undertake more extensive solutions.
I did major upgrades to both my RV4 and RV8, and I'm not a builder.

 

[SMRacer]

So here's what I did to my RV4 for a basic VFR panel on a budget. If I did it again, I would use an iPad Mini instead of the full size iPad.
Plus some performance information from the MGL Extreme EFIS. 8500 Ft, 2450 RPM, 175 MPH true.

 

[Roadjunkie1]

I am a very new owner of my RV-4, and am loving it. I'm up to almost 30 hours in it, and am starting to think about the long run of ownership, including making some modifications/upgrades, and wanted to get some opinions.

It's an O-320-B2A FP 160hp engine with a 68" wood sterba cruise prop, sam james cowl and short gear.

One of the more annoying things I have experienced is that cylinders 2 and 4 get extremely hot when I am at high power settings. I can rarely run WOT unless I'm way up in the 9-11k range because of CHTs. I find more often than not I have to climb up a thousand feet at a time, and then really pull the power back to allow the cylinders to cool, and I feel like I shouldn't need to do this. I've tried climbing at slower speeds, but it seems anything below 150 mph indicated really heats those cylinders up quickly, and climbing at 150 indicated results in a painfully slow climb speed. Is this normal?

Also, it has seemed that my cruise speeds are rather slow compared to other comparable setups. I can't cruise at much more than 140-145KIAS unless I really push the temps or get RPMs up into the higher 2600s, which doesn't seem to line up with what I have heard other RV-4 owners perform at. Might there be a reason for this?

The next thing I want to do is upgrade the panel. I'm rocking a *very* VFR panel. I am planning on removing the vacuum pump next week, along with the DG and ADI, both of which are inop. I have already ordered the cover and gasket for the vacuum pump. I think eventually I might go with a full glass panel, but for now I'm just looking for an attitude indicator so I can feel comfy night flying. Is a single G5 really as easy to install as it seems?

The last thing that bothers me is the location of my transponder and radio. I have an old Narco AT 150 transponder and a COM 760 TSO radio that hang underneath the main panel and kind of get in the way of my knees while flying. Eventually I'd like to get a better radio that isn't as static-y, but for now I am wondering if they might fit better in a different spot. If I do move them, I assume I'd need to cut a new panel. How difficult is that to do?

Like I said, I'm very new to all of this, and am just exploring my options, so I'm open to any and all feedback. Thanks!

Welcome to the RV-4 club! Best of the breed!

Huh. I have problems keeping my CHTs UP!! Sam James cowl is not standard but supposed to be good at keeping an engine cool. It might have something to do with the baffling, as previously stated. Most likely place to look. Look at the inside of the upper cowl and see if there are rub marks with no gaps everywhere the baffling rubber (or whatever) touches. Mine is black so it is easy to see. There ARE no gaps! And, again, what is HOT? Some people freak out at 350! Make sure your sensors and instruments are accurate. I designed my own metal surrounding the engine and, again, have problems keeping the temperatures UP. Sorry...............

With a similar engine setup, I cruise easily at 152kts at 2400 and can push 172kts at full throttle but suck down 10+gph. Naaaaa 174mph is fine with me! What is your GPS telling you? Pressure check your pitot system and make sure your static system has no leaks.

Go slowly on the panel. You have a flying aircraft now. It will be down time to redo everything. I LOVE the old-fashioned panel I have as it took me 6 months to design (a LONG time ago....) and I am very used to what it tells me. Close my eyes and point.......Good engine: pressure, pressure, temp, volts. I recently replaced the mEncoder with a Dynon and the Trimble GPS with an iFly. I like the radios in the console, and it never interferes with my knees.... Yeah: replace the TPX and radio.....

Got pictures..........?

 

[Capt]

I kept my panel simple, I fly for fun, no night, no IFR, I leave that to the jet I fly.
the 2x AvMaps are a nice simple inexpensive EFIS and they’ll drive an A/P in lateral mode with a basic DCT too function.

 

[jrs14855]

As a test and temporary measure you can back off the mag timing to 22 degrees. That will make a noticeable difference. I am quoting from memory but I believe Mahlon Russell has stated that he never saw any evidence of CHT up to 425 doing any damage ONCE THE RINGS ARE SEATED. That was based on hundreds of run out engines torn down at the old Mattituck Shop.
I ran my 0 360 powered Pitts for 1000 hours- no CHT gage ever installed. 3300 r/m all the time for aerobatics.
I thought Sam had a plenum on his personal RV4???

 

[RV7 To Go]

How "hot" are your temps? As well as what others have said regarding the baffling, make sure the inter-cylinder baffle is installed and the gaps sealed. Enjoy the 4, it is a blast to fly!

 

[fixnflyguy]

I did the G5 in mine..easy and very nice for a budget price. I'm not sure your Temps are reading correctly.

 

[777Dave]

Very happy with G5/GFC500 install. Not overly difficult or expensive.
In addition to tightening baffling, I had the carb jet size increased a little which was the key to lowering CHTs in climb. Even in Florida I never see anything over 370.

 

[hman1359]

Thanks for all the input, I really appreciate them. For the numbers on the CHTs, I'm finding it difficult to keep them under 400deg in climb. I have been using 410 as my hard red line where I level off and pull the power back to cool them off. When I level off and cruise at around 160mph indicated at 24-2500rpm, they drop to around 380-390 or so, which still seems high. Push it up to WOT/2700rpm and they creep back up to the 400 mark even in level flight. I suppose it's possible that they are reading incorrectly. The previous owner did the installation.

I'm going to have the cowling off next week for an oil change, so I'll check out the seals and try to figure it out from there.

 

[Rick RV-4]

Please be more precise with your speeds so we can help out. You mention speeds in KIAS. If you are getting 140-145 Knots INDICATED airspeed at 2,000 feet, then yes, that is slow. If that is up at 9,000-10,000 feet, different story.

Have you done a 4-way grounspeed check? If so you should be seeing at least 180+ miles per hour TRUE airspeed (or 155 knots) up around 8,000 feet or so density altitude.

 

[jrs14855]

With the cowl on shine a bright light in the inlets and see how much light comes out around the baffles. I don't know it the inlet ramps apply to the 4. Check for condition and openings around the inter cylinder baffles. Also check that the ends of those baffles are tight against the cylinder fins

 

[YellerDaisy]

A few more items to ponder.
1. While the cowl is off, shine a flashlight all around the bottom side of the cylinders/baffles and look on the top for light getting past. There are a few spots that are difficult to seal up.
2. Double check that you have the inner cylinder baffles installed (on the bottom of the cylinder bases).
3. Confirm your baffles have the modification to allow air past the back of #3.
4. Confirm that your mixture control arm is full rich when the cockpit lever is full forward/rich. Some of the quadrants that we use have a limited throw and are a bit short preventing full rich mixture. Many adjust for idle cutoff but then end up lean at the other end.

It is a bit interesting that your hot cylinders are 2 & 4 (one side of the engine). It seems like either the front or back cylinders tend to be hot - versus side to side. But... I'm sure anything is possible.

Accurate speed data is a bit of work to obtain. There are a number of good articles online regarding how to do this and it is very helpful if you establish some baseline numbers under specific conditions and then always repeat this for comparison (to accurately measure whatever changes you've made). Typically, 8,000' DA is a good place to take measurements - but that can depend on your location. There are times of the year that my field elevation is higher than 8,000 so I sometimes use 12,000' DA.

For comparison purposes my not super fast RV-4... The last data that I can find when I had an O-320 (160hp) was in 2019. I recorded a 150 kt average GPS speed (four way average) at 8,000' DA at 2500 rpm and 1450 lbs. I'm not seeing a full throttle run. With an O-360 and prop set to 'sorta climb/sorta cruise', I've recorded a four way GPS average of 161.5 kts at 12,000' DA, 2700 rpm (not full throttle due to prop), and 1400 lbs.

You were asking about cruise. I'm at high elevation and typically cruise 8,500'-10,500' -ish. At those altitudes and a 2400 rpm cruise, I only see 120-125 KIAS. However; the TAS is what really matters. I don't do it very often but it seems like pushing it up results in indicated airspeeds up in the low 140's.

I suspect the amount of work for a panel upgrade depends on your starting point. I had my airplane in pretty good shape (electrically speaking) and then upgraded the panel (written up here). I did as much work as possible before taking the airplane out of service and, if memory serves, was back in the air in a couple weeks. The EFIS's that are available now are very impressive, toss in ADS-B and autopilot (once you install servos) and there is a lot of bang for the buck there.

You'll hear all sorts of cooling scenario's with RV-4's. Some are great, some not. Mine was ok-to-warm with the O-320 and similar with the O-360 (new cowl, baffles, everything). A cruise climb of 100-110 kts should be helpful if everything is setup/running as it should.

Hope that helps... they are a very sweet airplane!!

 

[Marlonyoung]

G5 was very easy to install, did the same thing and removed all vacuum. installed a dedicated antenna for it, Forward of the firewall and now gets great GPS signal.

replaced the old transponder with a newer Garmin ADBS OUT with the slick little encoder all on the right side of my cockpit, out of the way. Will try to find a picture.

 

[777Dave]

G5 was very easy to install, did the same thing and removed all vacuum. installed a dedicated antenna for it, Forward of the firewall and now gets great GPS signal.

replaced the old transponder with a newer Garmin ADBS OUT with the slick little encoder all on the right side of my cockpit, out of the way. Will try to find a picture.

Didn’t use the encoder included with the G5? I added a separate GA56 gps antenna as well.

 

[Xkuzme1]

It does seem that something is off.

O-320 160hp here. I’ve never seen CHTs above 400. Oil temps are usually a tad on the low side as well.

I normally cruise at 165-170kias with My Sensenich metal 2BL prop. She normally doesn’t fall all the way off until 14,000.

I’m wondering if your cowl/prop combo isn’t pushing enough air into the cowling. There is a Sensenich 3 blade ground adjustable prop for sale right now in classifieds. I would seriously consider looking at that first.

Baffling would be my second guess. Airflow in and around the engine as well as turbulence.

Hope you get it ironed out.

X

 

[Taltruda]

It does seem that something is off.

O-320 160hp here. I’ve never seen CHTs above 400. Oil temps are usually a tad on the low side as well.

I normally cruise at 165-170kias with My Sensenich metal 2BL prop. She normally doesn’t fall all the way off until 14,000.

I’m wondering if your cowl/prop combo isn’t pushing enough air into the cowling. There is a Sensenich 3 blade ground adjustable prop for sale right now in classifieds. I would seriously consider looking at that first.

Baffling would be my second guess. Airflow in and around the engine as well as turbulence.

Hope you get it ironed out.

X

165 to 170 KNOTS indicated airspeed on a O-320? I think someone either has the fastest RV that I’ve ever heard of, or someone stuck a 300hp IO-540 under your cowling when you weren’t looking..

 

[Xkuzme1]

165 to 170 KNOTS indicated airspeed on a O-320? I think someone either has the fastest RV that I’ve ever heard of, or someone stuck a 300hp IO-540 under your cowling when you weren’t looking..

Let me clarify. I file for 165kts TAS.
You are correct. I am not cruising around at 165-170 indicated. My mistake.

 

[jull_under]

It does seem that something is off.

O-320 160hp here. I’ve never seen CHTs above 400. Oil temps are usually a tad on the low side as well.

I normally cruise at 165-170kias with My Sensenich metal 2BL prop. She normally doesn’t fall all the way off until 14,000.

I’m wondering if your cowl/prop combo isn’t pushing enough air into the cowling. There is a Sensenich 3 blade ground adjustable prop for sale right now in classifieds. I would seriously consider looking at that first.

Baffling would be my second guess. Airflow in and around the engine as well as turbulence.

Hope you get it ironed out.

X

Where's the link to the 3-blade Sensenich for sale ?

Thanks !

 

[Xkuzme1]

Where's the link to the 3-blade Sensenich for sale ?

Thanks !

I guess it sold. It was sharp. Black with red tips. Sorry you missed it.

 

[hman1359]

Little up date on the work I have done this week. I did some investigating into the baffles, and sure enough the neoprene boot that connects the left inlet to the plenum was loose. I connected it securely, and am hoping to see a decrease in temps when I take it up next. also going to do an oil change next week and will check the connections on the CHT probes at that time.

Unfortunately, I made the mistake of opening pandora's box (the instrument panel cover). I got the vacuum pump off without dropping anything somehow, and put the lycoming gasket and cover plate in the slot to cover it up. Turns out the spline shaft that fit into the accessory drive on the back of the engine was just straight up missing, so the pump wasn't even turning. I removed the ADI and DG as well. the real headache was the situation of the wiring behind the panel. It is everywhere, with unused wires strewn about, and systems/instruments/equipment that I don't even know their function just hanging around. I have attached some heinous pictures if anyone would like to help me figure out what is going on back here. I'm still working on getting the rest of the vacuum system removed, so that will be a nice declutter, but the rest of it is terrible.

Specifically, I don't know the function of the tube through the firewall that goes through a filter and then into the black connecter with the orange plug attached to the firewall, as well as the Scosche power noise filter. Anything else weird you see and can point out would also be much appreciated.

Thanks again for all the help so far!

 

[YellerDaisy]

My guess for that tube is manifold pressure sensor.

Many of our older airplanes benefit greatly from a mid-life overhaul of the electrical system. The problem is 'while I'm at it'... A small job can quickly turn into a large one.

 

[fixnflyguy]

I'm just catching up on your "issues" as I haven't been keeping up with things lately. You have my number and I wish you'd have given me a shout. The neoprene connectors to the plenum are home made, and yours are almost too short. I have read others use wetsuit material to make ones. Not glamorous, but functional. I have some neoprene sheet in grey or red that may be better. As I mentioned in earlier talks with you, the vacuum system wasn't really needed. Only your turn coordinator gyro is on it. Ditch that heavy thing anyway. The wiring is another story, and your plane is not unique to that. Anyway, give me a shout or come visit sometime.

 

[71459]

I LOVE the old-fashioned panel I have as it took me 6 months to design (a LONG time ago....) and I am very used to what it tells me. Close my eyes and point.......Good engine: pressure, pressure, temp, volts. I recently replaced the mEncoder with a Dynon and the Trimble GPS with an iFly. I like the radios in the console, and it never interferes with my knees.... Yeah: replace the TPX and radio.....

I agree completely. The flat panel stuff looks ridiculous in an RV-4. It's just not "period correct", and for the mission the airplane was designed for is unnecessary overkill. But it is shiny and it lights up, so there is going to be an attraction there.

 

[tass]

I don't know the function of the tube through the firewall that goes through a filter and then into the black connecter with the orange plug attached to the firewall

Where does the engine-side go? In my plane, I have a MAP sensor (for the EFIS) sitting behind the firewall, and it's routed in a similar way. Metal tube to the cylinder on top of the engine (though could also be the bottom) which transitions to a clear plastic hose behind the FW and fits into the MAP sensor.

 

[Roadjunkie1]

Let me clarify. I file for 165kts TAS.
You are correct. I am not cruising around at 165-170 indicated. My mistake.

I file for 165 as well....but MPH. Looking through my old travel logs (no, I don't save EVERthing... ) my TAS averages about 175 mph/152 kts at 24/20 and 7.1-7.7 gph or ~7.5 average. I can push her to 200 mph (174kts) but she is sucking down 10+ gph and sounds like she is working pretty hard! She likes 2400! Me, TOO! Smooooooooth....... and going faster than the Cub.........

 

[hman1359]

I'm just catching up on your "issues" as I haven't been keeping up with things lately. You have my number and I wish you'd have given me a shout. The neoprene connectors to the plenum are home made, and yours are almost too short. I have read others use wetsuit material to make ones. Not glamorous, but functional. I have some neoprene sheet in grey or red that may be better. As I mentioned in earlier talks with you, the vacuum system wasn't really needed. Only your turn coordinator gyro is on it. Ditch that heavy thing anyway. The wiring is another story, and your plane is not unique to that. Anyway, give me a shout or come visit sometime.

Thanks Bill. I actually have some neoprene as well for other purposes, so I'll take it out to the hangar and cut some longer connectors. I'll get in touch with you in the next week or so with some more questions I've been meaning to send your way.

 

[hman1359]

Where does the engine-side go? In my plane, I have a MAP sensor (for the EFIS) sitting behind the firewall, and it's routed in a similar way. Metal tube to the cylinder on top of the engine (though could also be the bottom) which transitions to a clear plastic hose behind the FW and fits into the MAP sensor.

Interesting thing to point out. I have a D-10 EFIS but it does not indicate MAP, however this makes the most sense. The plumbing for the metal tubing disappears under the right side of the engine, and if my research is correct 4-cylinder Lycomings typically pull MAP from the bottom of the #3 cylinder. Another earlier comment also suggested this.

Assuming that's the case, is it even worth keeping the MAP around? I have a FP prop and I don't think I've ever really seen an engine display MAP with a FP prop. I also have no interest in changing to a CS prop.

 

[blaplante]

Regarding wiring... when you install your new equipment, use https://www.amazon.com/gp/product/B07NZ51DQC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Dymo labelmaker compatible heat shrinkable tubing. Then you can label that random wire and some poor future guy will be a bit less frustrated. That guy could be you 4 years from now!

 

[blaplante]

With MAP and OAT many EMS systems will auto calculate percent power for you. Handy so you can stay under 75%.

 

[blaplante]

Given you have a Dynon D10 EMS already, you might want to consider the Dynon D10A for a PFD. They can often be picked up used.
Swapping to some other engine monitor often means swapping some/all of the sensors which drives the cost up.

 

[tass]

4-cylinder Lycomings typically pull MAP from the bottom of the #3 cylinder

Yeah I think this is typical, but mine pulls it from the top of cylinder 1... I've been told it doesn't matter, and assuming it was done this way when converted to a C/S prop as the primer was already set up from below.

As for removing it, is it hooked in to a sensor that's available to the EFIS? If it logs MAP, even if not showing it, it could be interesting information for later analysis.

 

[n82rb]

I agree completely. The flat panel stuff looks ridiculous in an RV-4. It's just not "period correct", and for the mission the airplane was designed for is unnecessary overkill. But it is shiny and it lights up, so there is going to be an attraction there.

got to disagree with you. the biggest plus for the flat glass is information. the cockpit of the 4 is tight. not really even enough room for an ipad. with the 10" skyview in mine i don't need an ipad, charts, paper or anything. makes CC flying a breeze. the only thing i needed to get into S&F was a a sticky note with the freq's written on it. all the waypoints on the arrival were programmed in the flight plan.