I know these have been discussed a lot, and I've read most of the threads, and I've seen just enough negative on them to make me cautious.

I've read both of Clarence Lee's reviews- the 90SP and the 120SP- and he really liked them and recommended them. He didn't have any of the problems reported by users, and the engines he tested were older versions.

I'm thinking about getting a 90SP for my Hangar 9 Camel.

I'd love to know what the "final" group opinion is.

these engines are not the norm, many of the problems have been caused by insufficient ducting of air onto the fins, sort this problem out, and you have a bb=etter chance of them behaving, we sell them, and have to explain the ducting thing quite a lot, i always hand enquireses over to another guy who uses them, but, i cannot see the beneift in your camel, surely this would be better with a standard motor? or a saito twin?? the SP series are ment for tight cowls, as an inline engine instalation

I have 2 RCV90SP's that I dearly love. One is an older engine turning a 4 blade prop on a TF Mustang and the other turns a 4 blade prop on my son's TF Spitfire. I would and will buy another one just as soon as the need arises. I trust the RCV engine and their service staff also.

David

Thanks, Alan and David.

Alan: The Hangar 9 Sopwith cowel is too small to completely enclose any conventional, overhead valve four stroke. It is, however, large in relation to the size of the 90 SP, so constructing duct work to channel the incoming air over the fins should be relatively easy. The left pic shows a conventional four stroke (Saito, I think) and the right one shows the 90 SP in the same model. Mostly, though, I like the idea of being able to turn an 18" prop, which is almost scale size for this bird.

David: which 4 blade are you running on the TF Mustang? I have one under construction and at first thought that it would need the 120, but after seeing how close the 90 and the 120 are in power output (Clarence's tests) I'm wondering if it's really necessary.

The problems I encountered with the SP's (3x 120's) were due to detonation hammering them, and anything connected to them, to pieces.
My investigation found that fuel, and run in time, were critical with these motors.
Also, the bottom end had to be set just right or mid range problems were encountered (vibration, detonation)
The 120's kept blowing the ends out of the supplied mufflers, and I did have my doubts about the cheap Chinese carby's being used.
When they are running right, big 4 blade prop attached, the pull like a freight train and have a very pleasing sound, quite different to other 4 strokes.

RCV in the UK have the best customer support I have come across. In the end they fully refunded me for the motors plus freight.
I still wish I could have sorted the problems I was having, the P-61 would have sounded ausome with 2 x 120's in sync.

A friend has a 60SP which went well until a mid air took him out on the 5th flight. We have just put it into his Ugly Stik and have yet to test fly it.
Again, vibration in the mid range was evident, but we are still running the bottom end rich which will be attended to during field tuning.

Hi Bob,

As I'm sure you know, I'm an RCV SP fan for thier ability to fit in a tight cowl and turn a large prop. Perhaps the CD version will meet your needs. The CD version runs 1:1 and turns a conventional size prop but still uses the rotary valve. This means that it doesn't have the tall head that other 4 strokes need for conventional poppet valves. It's profile is more like a two stroke, and may fit your need.

Scott

[size=5]I'm using a Bolly 18x12.5 on both of my planes. The ducting seems to be important so I increased the ducting on both with no trouble and I would suggest that you do the same also. I did have a Saito 1.00 in my Mustang but the RCV fit and sounded so much better. I don't think you could go wrong with one. Both engines took a little longer to break-in but they were such a big hit at my club that I got all the help I needed.

David[/size]

I made a mistake I used a Bolly 15.5 x 12.5 4-blade prop not an 18" prop as previously stated. I used an 18 x 12 2-blade prop to break in both motors. Sorry about the confusion.

David

I have both the RCV60SP and the RCV91CD, both are working flawlessly and they tend to get stronger with time. I due like to stress that the break in period is very, very important. Not only that but also make sure they have plenty of cooling. Follow the recommended props as well!!!! Once you achieved these goals they should not give any problems. I'm planning on getting the VQ FW190 once they are released and I'm planning on getting another RCV SP series engine for the FW190. Customer service is also WORLD CLASS!!! O yeah.....almost forgot, the sounds of these engines are incredible!!!!

I've run one of these engines(90sp) quite a bit and I'll throw in my 2 cents:
Good: Scale size props and tremendous torque. They can produce a lot of thrust for the size. Great engine sound! Very small size, will fit in very narrow cowls with little or no cutting. Great customer service.

Bad: Heat is an issue, good ducting is a must. Vibration seems to be a problem on mine, everything on the plane wants to loosen up, but this has improved with more running. Seems to be some variability in these motors, mine was very tight when new but it produces a ton of power, doesn't idle worth a darn though( has improved with more running). These motors are quite heavy for the displacement, really only suitable for warbirds or similar planes that need nose weight. The idling problems I have encountered combined with the high pitch props have led to some real landing challenges, ie fly it down and hope it sticks. Starters: either have a dedicated starter and mount the stud on it to use the behind engine cam, or have one heck of a high torque starter for turning the spinner.

All in all, in the right right situation (tail heavy plane and or restricted mounting space), it is a great motor but there are definitely some limits and considerations.
James

Cooling is certainly a concern. With my TF spitfire, I came up with a somewhat unique solution. I pull air in from between the spinner backplate and the cowl and made a cone shaped baffle to keep the airflow across the fins. Of course, there's virtually no prop wash into the gap between the spinner and cowl, so instead of using the prop wash to blow air into the cowl, I use a small electric ducted fan to blow air out the back of the cowl thereby sucking cool air in. I've had this running with an ECS controlling the fan with a knob on the radio. I'll be modifying this to use a thermocouple sensor/controller to control the ECS. It was originally designed to operate cowl flaps.

Scott

I have two... a 90SP and a 60SP. The 90 is in a H9 Corsair. The 60 is in a 40-size Mustang. There are two things I really like about these engines... they turn a big multi-bladed prop, and everything (except for the very tip of the muffler) is hidden in the cowl. I love these engines and I'd buy the 120 SP if I had the time for another project.

Juice

I'm just glad to see the SP engines getting more and more users. I have 1 60SP, 2 90SP, and 2 120SPs. Three are still in the box, got a heck of a deal on them. I am still breaking in a 90SP and a 120SP. The bearings on the starter bolt have failed twice on my 90. Could have been the fact that I was running it flat out while breaking it in. The 120 has been flawless minus the vibration. The most improtant thing to remember is getting it tuned to run as smooth as possible. I have been running the 120 about 4000 RPMs. The benefit there is I get 25-27 minutes of breaking time and the engine isn't being stressed to the max before it is fully broken in. I have been able to get it to idle at 1300 rpms which is less than the recommended idle.

When you buy RCV SP engine, go ahead and get a O.S. muffler to go with it. The RCV mufflers aren't the best quality, the vibration and heat will do them in. Once you have the engine broken in put the O.S. muffler on retune and fly.

Like the other guys have said, make sure you get your cooling ventilation set up right. They recommend 2:1 or 3:1 ratio. 3:1 being the best.

I put my SP120 on a Balsa Nova to break it in. The guys at the field thought it sounded like an outboard motor because of the gear whine. It performed OK as long as the muffler stayed assembled. It took itself apart on every flight. I even drilled thru the threaded section of the muffler and installed sheet metal screws. It shook those out and and then fell apart anyway. Of course when that happens the engine goes lean and wants to die. It also exacerbates the heat problem. The torque transferred to the firewall is doubled because of the gear reduction. The firewall started to leave town after 8 flights or so.

There was not a problem setting the mixtures. I returned the engine to England and they replaced the muffler with a single piece design. They also said they had updated a few things....no charge. They also stressed getting air to the engine and the muffler. They thought round cowls were OK, but suggested getting the muffler outside of the cowl on narrower installations.

I have installed it in a H9 Corsair, but haven't flown it yet. After seeing some of the disasters with the firewall on that bird, if anything can remove the firewall from it the RCV can. I need to rip everything out and reinforce the firewall joint.

I plan to buy a couple more RCV's for a twin. I like the basic design. I'm thinking it might be just the ticket for my PICA P-51 too. Maybe run the oil tank back to the oil cooler. Recommended prop for the 120 is an 18X12. I was surprised that some of you were using that prop on the 90.

Gordy

In the docs the recommended prop for the 120SP is a 20" x 12" 2 blade, 18" x 12" 3 blade or 15.5" x 12" 4 blade.

The vibration is the killer, I would be interested to hear how you go with the 120Sp, I had 3 die on me.

I also bought them for a twin and my TF Corsair.

Thanks to all for your honest assessments. I think I'm going to stick with the Magnum 91 two stroke that I have in the box. I really like the design and function of the RCV's, but I'm still hearing about too many issues that could (or should) have been corrected some time ago. If the things weren't so dang expensive, I'd be willing to put up with the issues, but there are some very nice engines available on this side of the pond for that kind of money.

For an H9, I would tend to agree. Save it for a project along the lines of your Mustang.[8D]

Mboland

Thanks for the prop recommendation update. I dug out the papers on my 120 and they do say use an 18x12 for the 120 and also for the 90! They are dated 2001. I can't believe I've had that engine that long. I'll bet it will run better on a 20" prop.

Gordy

Just as an fyi for anybody new reading this thread... mboland's SP failures were eventually tracked down to the fuel he was using. Far too high of an oil content was destroying the engines. His local dealers were recommending incorrect fuel for his SP's.

He talks about it a little more in the RCV sub-forum.

RCV engines come with a 2 year warranty, so obviously if RCV engines were prone to dying at such a high rate RCV would be out of business in a real hurry!

Regards!

- Michael

Gordy, just remember that RCV says that you should not drop the pitch below 10.

Scott

I've got a rcv60-sp. Hasnt been mounted on a plane yet, but has had several tanks run through it. So far, I dont trust it for reliability yet. I cant keep it running without the glow driver still being attached. I had wanted to mount it on a Kyosho Corsair since it can spin a large prop, but, since that plane is not replaceable, I am very hesitent to use the motor yet.
Maybe I should save it for the Kyoso FW-190....not sure. At least that one can be replaced(once its released on march) Suggestions? Comments?

Kahlog, that shouldn't be! I'm breaking in a 90SP on the test stand and from the 1st time I fired it up I haven't had any problem taking power off the glow plug... it keeps running as normal.

There's either something wrong with your engine/plug or else there's a problem with the fuel you are running. I'd suspect the plug or the fuel 1st though... one of them isn't quite right.

From what I'm reading RCV is finally backing off on the Caster Oil requirements for the SP series of engines. They told me (in the RCV sub-forum) that running full synthetic "Cool Power 10%" is perfectly acceptable. My 1st tank of fuel I ran thru my engine was another brand with about 8% Caster Oil and the engine slobbered dripped and puked oil everywhere. I'd borrowed that tank of fuel from another club member as I only had Cool Power for my OS 2-cycle engines.

RCV then posted that it was ok to use Cool Power (which is all I've used for my airplanes and heli's for the last few years). So my 2nd 16oz tank of fuel was Cool Power 10% and the engine doesn't slobber drip or puke oil out the crankcase vent now and runs alot "easier" sounding. Also seems to run alot cooler now (though that could just be because it's not quite as tight as it was on the very 1st run with that other fuel).

Find the RCV sub-forum under Engines on here and post everything you can about your engine's setup and what type of fuel you're trying to use. You engine should NOT be behaving thatta way!

- Michael