Thunderbolt IO-540 in a RV-10

With the engine out of the box (beautiful job on packing by the way) I was able to start seeing how this was going to fit in the RV-10. Putting a IO-540 in a 10 is not new by any means, but there are a couple of differences in my Thunderbolt build over the standard IO-540. Mainly, this engine was built closer to the specs of Red Bull setup rather than the stock balanced setup.


The first hiccup were the mounting ears. I had pulled out the dynafocal mounts and something didn't seem quite right. After a bit of research I found out that there are two sizes the large hole 19770 mounting ears are typically used on the 300 Extra and the Rockets. Unfortunately, the RV-10 engine mount is setup for the small hole 70456 mounting ears. In all honesty, I figured this was my problem and I was about to purchase a set on e-bay when I had sent Thunderbolt (Jeff Schans) and email with my situation. I sent that message late on Saturday and received an immediate response saying that they would get a new set of small hole ears color matched and sent out ASAP. Hurray!

Those came to my house within a couple of days and solved problem number 1!



Problem number two I was expecting, but I was not sure if it was going to be true or not until I got my mounting ears in place and the mount up next to the engine. I ordered this engine with the cold air induction. This cold air setup is again, off of the Red Bull series planes and can be found on the AEIO-540-L1B5. From a dimensions standpoint it looks a bit like the BPE setup. As you probably know, the BPE setup needs a modification to be performed on the engine mount in order to clear the sump. The Thunderbolt has similar clearance requirements.


With the top mounts in place, the oil screen boss *ALMOST* clears the engine mount. In all honesty, I did not try putting the lower mounts in first and then the top mounts to see if everything was going to clear. It may have, but when I saw this, I decided to just go ahead and lower the bar.




I had been expecting this, so a couple of weeks ago I had purchased a pre-bent bar from BPE.


If I were to do this again, I would probably the bar just a little further. Everything looks good, but there is no reason with the mount off of the fuselage at this point to not weld something in that should be compatible with other setups.


That is it for now. I just placed an order for the PlanePower vacuum pad mount alternator and a B&C oil filter spacer and adapter. Hopefully that will be the next post to detail how the rear of the engine looks with some of the accessories installed.

Thunderbolt YIO-540-EXP43

While the engine is off of the plane and none of the accessories are mounted I figured it would be a good time to take some photos of the engine. This is a YIO-540-EXP with the cold air induction off of the AEIO-540.



I had Thunderbolt remove the magnetos because I wanted to put in electronic ignition and there was no reason to pay for something that I was going to take out right away.


I will admit, I was not expecting this to be in the order. A FM-300R was a nice surprise. This is their light weight high flow unit with adjustable main jet, used on race planes (it was designed for the Red Bull race series). It makes sense, because I ended up getting a lower compression Red Bull engine from Thunderbolt... I talked a bit with Airflow if I should be running a 300R in a plane that I want to just turn the key and start after getting crabcakes in Tangier and here was Don's succinct response.  "The FM-300R is the Mac Daddy of our fuel control line.  I don't really know why you would want to switch from the FM-300R to a FM-300A.  If you are after the purge valve function you can just add the purge valve to your flow divider, of course your will need to install a return line to one of the tank feed lines and install a push-lock cable in the cockpit to operate the purge valve.  With the FM-300A you would need to use the purge valve for stopping and starting the engine (The mixture control valve is a rotary valve therefore ICO is not zero leak although it does give you the added ability to circulate fuel through the fuel injection system to purge hot fuel and vapor from the engine before starting).   The FM-300R has a different designed mixture control valve which is zero leak so the purge valve is not required for starting and stopping the engine."



Hartzel 200F-5002 Fuel Pump


The engine came with the large hole 19770 mounting ears and Thunderbolt quickly shipped me a new set of small ear 70456 models that work with the dynafocal mounts that we use in our RV-10s.


API Flow divider


Sky Tech Starter




Fly wheel and mounting boss


Chrome Rocker Box Covers


Cold Air Induction

MT Governor stud length

Previously I had installed my MT-860-3 but noticed that the studs were a little on the long side. I tried screwing them in a little further, but it felt like they were already bottomed out.

Here you can see that the stud threads are obviously too long to the point where there is non-threaded area showing past the governor.



Jeff Schans at Thunderbolt sent me next day a variety of stud lengths to rectify this. On the bottom is the original stud followed by some of the replacement options that Thunderbolt sent to me.



One thing I noticed as I was going through this exercise was that upon removal the threaded blind hole in the case was actually a lot deeper than I thought it was. So rather than swapping out the studs, I set the existing stud a little deeper and all was well. Sorry for the run-around Thunderbolt. Thanks for working with me.



Now back to research on the 860-3. I noticed that everyone seems to be using the 860-5 now. I have to go find out if I need to swap this out.

Cross bar dimensions

I keep forgetting to make a post about my engine mount crossbar dimensions, so while this is old news I still want to document it. With my cold air induction (Thunderbolt) I had to lower my crossbar in order to gain enough clearance for the engine.  The short of it is that the rear of the sump on the cold air setup is about ~3/4 lower than the standard sump.

This is a pretty standard modification and Barrett sells these crossbars with their cold air induction. The dimensions of my setup are in the photo below.

I unfortunately measured once and cut/welded twice. The first time I welded one in, I more or less eyeballed in the dimensions while the engine mount was on the weld table and not on the airframe. After I mounted the engine and allowed the mounts to sag a bit, I was not happy with the clearance I had remaining (1/16"). As such, I removed the engine off of the mount and welded a new cross bar in place. The tubing was pretty easy to find and I just ordered it from: McMaster Link

With the Thunderbolt IO-540 setup with Cold Air, .82" of cross bar drop got me a little over 1/2" of clearance on a mostly settled engine.

Intake Decisions

I have a FM-300R, the Show Planes cowling, and a Lycoming Thunderbolt IO-540 with a cold air sump off of a L1B5 ordered the intake from Bryan and Showplanes, but things are pretty tight.

BLUF, here are the paths I am debating right now:

1. Build a custom snorkel that is going to have some pretty sharp angles and a pretty funky setup around the FM-300R inlet
2. Cut a hole in the Show Planes lower cowl and install a Rod Bower ram air setup and fairing
3. Cut a hole in the Show Planes lower cowl and build a new air box/inlet

I have been swapping some components back and forth to see what option was going to be the best. To start, the FM-300R needs about 1/8" of additional clearance when using the 4 degree Airflow performance adapter. Right now I have been working with Don at Airflow and he has a cable bracket in prototype for this that not only holds the cables, but also gives me the additional clearance needed to fit the FM-300R with the L1B5 sump.

Airflow Performance straight spacer.

Airflow performance prototype linkage adapter.

This gets me pretty well setup without the cowl and intake. Getting the Showplanes snorkel intake in place with this setup is pretty tight. Well I guess it is a little more than tight as it doesn't fit. Here is the lower cowl installed in its final location with the FM-300 on a straight (NOT 4 degree) spacer.  There is about 1" of clearance between the servo and the cowl.

I ordered the straight spacer because with the 4 degree spacer, the intake transition had some clearance issues with the PlanePower 70A externally regulated alternator. As a note, the larger tube is not even on the "T" yet, this is just the T without the step up to the larger diameter tube that goes over the air filters. Also, this is with the alternator in the center of adjustment. Obviously, nothing is cut here either. I still need to transition the T to the FM-300R which has a lip on it for clamping purposes. I could bring this version of the T aft a bit in order to gain a little more clearance.

With the 4 degree spacer, there is much more space to work with.

With the 4 degree spacer, the 1/8 control linkage adapter, and the lower cowl put in place, there is roughly 2.25 inches of clearance. Which is not that bad.

With 2.25 inches of clearance and the angle of the cowl, this is what a 4" tube for a T would look like.

Here is what a non-deformed 4-5/8"s looks like. Mind you I have not run the engine yet, and you would have to expect that there would be settling that is going to occur as well as movement while running. This is the final dimension of the stock Showplanes intake tubing. 

For the left side of the intake, there is quite a bit of room to make the run directly up from where the notion T exists in the previous photos. The right side however there is not a lot of room between my vetterman (custom) exhaust and the PlanePower alternator. I was contemplating getting a smaller alternator, but I might as well not add those constraints to the setup if I am at this stage of the build.

This is pretty hard to see, but this photo is taken from the left side of the engine looking at the right with the T and the snorkel resting where ever I could get them to fit. The angles are possible to make, it is just a shame that this is the intake and there are going to be many >90 degree transitions.

Which really has me thinking why not just punch the intake straight out. I have been thinking about the Rod Bower design and I have an email out to him.

There are just sooo many bugs in Virginia that I feel like a large percentage of my flying is going to be with the ram air door closed sucking the warm air out of my lower cowling. I have been thinking about leveraging the C172 design.

I have also been looking at making that a little sexier and mimicking what the Sam James cowl looked like at one point.

FM-300R on a L1B5 sump

This is a post that is completely out of order as I forgot to publish it when I was working through this fit up. I have a Lycoming Thunderbolt IO-540 with a cold air sump off of a L1B5. when trying to put the FM-300R onto this sump I ran into a bit of a snag. i.e. the sump is in my way!

As you can see here I have about an inch and a half up or out that I need to get in order to get things to line up. I think the BPE cold air sump has a very angled forward face to it that allows this fit up to work.



No real big deal here. This is a standard problem which many places sell spacers for just this problem. In my case I called Don at airflow and ordered a 4 degree spacer. I figured this would do the trick. So close!!! I am about 1/8" from fitting.If you look at the top corner of the spacer you will see it pulled away from the sump because of the top of the servo contacting the sump.



I have the servo on upside down here just to take a photo. This brass hex (the adjustable jet) is what is contacting the sump. I did contemplate just taking the 1/8" off of this hex. Also, Don had mentioned that we could remove the adjustability out of this...


I went back and forth with Don though, and Jeff Schans shipped him out a sump to work on some fit ups. Don agreed to help prototype a new bracket that would push the servo out the 1/8" while also giving me a place to mount up the linkage cables.

Presumably the straight spacer could be pulled back closer to the sump, but I am not sure that buys you any cowl clearance because the straight spacer will be pushing the servo inlet closer to the cowling.