Wow nothing like skirting the issue... MR. JAOJET you were made aware of a problem.. yes we have an issue with one our engines blowing a wheel (literally) so please send this back to us at your expense and we'll fix our problem for you...

The more I read of this the more certain I am that I would never buy one of these engines.

I bought mine in 2009 new of Wren and changed my plan and had no home for it till 2011 at that point I was aware of the issue regarding the compressor and got onto Wren about it I send the turbine back to them unrun and got them to carry out the upgrade of the compressor and the diffuser at a nominal charge as technically the turbine was now out of warranty the whole issue was dealt with in a very professional manner by Wren

.When 2.4 was first introduced JR and Futaba had their share of problems and the consumer paid the price. These two companies never had a recall did they and it took the hobbyist to force their hand. The poster is doing the same thing and should be applauded.

This is a better post... I'm not looking to bash a reputable manufacturer but there is a responsibility here to maintain reliability and workmanship. There will always be issues with anything electronic or mechanical. How a company deals with an issue is key. Toyota took a horrible stance to stuck accelerators when the issue first began to surface but eventually stepped up to the plate and began to resolve the problems. Wren knew there was an issue and should have issued a recall. Same as Toyota. it does not matter how old the vehicle is. Bad design is bad design regardless of warranty.

If the wheel is coming apart it is most likely a design flaw in that the strength of the wheel is simply too low. The air coming in at an odd angle shouldn't affect it. The loads on it are mainly proportional to the square of the rpm. Reducing the rpm a few thousand rpm takes a lot of the load off of it. But how much is the wheel really under designed? Better materials can help-going to a machined vice a cast wheel- but obviously it isn't enough in this case.. The stresses are simply just too high on this particular compressor wheel design. Options are To make the new wheels out of an even stronger material, will the weight increase? then is the shaft strong enough? Then does the acceleration suffer? Total redesign required..

The only people that paid the price is Jr/Spectrum with there 4 iterations of 2.4, Futaba FAAST has been solid from day 1.

[QUOTE=ash 26;11745811]I bought mine in 2009 new of Wren and changed my plan and had no home for it till 2011 at that point I was aware of the issue regarding the compressor and got onto Wren about it I send the turbine back to them unrun and got them to carry out the upgrade of the compressor and the diffuser at a nominal charge as technically the turbine was now out of warranty the whole issue was dealt with in a very professional manner by Wren

Why did you have to pay even a nominal charge for an upgrade? Again, the owner has to contact wren about the issue, then the owner has to send it to wren, then the owner has to pay wren for his new but "old and out of warranty engine" to be upgraded or repaired? And people are seeing this as " very professional "? Did wren ever communicate to 160 owners about a potential problem? No, they simply waited for these engines to fail out of warranty and then proceeded to charge for repairs and sell upgrades to uninformed customers. Even my engine had ecu problems that caused flame outs with the original owner. He sent the engine back to wren and was promptly charged for a ecu upgrade to projet even though the engine was still under warranty, he paid the bill and also thought the service excellent! Why did he have to pay? Why would anyone buy a engine at the full purchase price, then pay for an upgrade, to hopefully make your new engine reliable and safe? And then pay yet again should it fail? If you buy an engine from a company like wren, would you not expect it to be an expertly engineered and thoroughly tested and supported piece of hardware?

[QUOTE=ash 26;11745757]And where you not told that there there could be a chance that it could blow up and to send it back to Wren before you run it.
I know of a couple that have 17 and 22 h on them with the upgraded compressors and no issues what so ever[/QUOTE

Yes, I was warned that it could happen, but was told that this one was checked by the wren factory and thus was OK. At that stage I was not aware of the scale of the problem, but bought the engine in ignorance. I was buying a WREN engine! How bad could it be? Surely, if there really was an issue, the owners would have known of it? If only I knew then what I know now!

I also know of a couple with upgraded wheels that is now resting on the bottom of False Bay in Capetown, their owners fed-up with having to pay all the time!
http://www.rcuniverse.com/forum/rc-j...-broken-5.html

Just to clarify one thing. My Wren 160 had no problems with the compressor. In my case the turbine wheel shed a blade & destroyed the engine.
After some debate, Wren supplied me with a new turbine. They were eventually professional in this case.
I have had problems with them in the past with another 160 I had, & was not satisfied with their service & charges on more than one occasion.
I no longer have any Wren turbines & now use other makes.

Really?? You seem to forget about the Futaba GUID code debacle.....just say'in��

So are you saying you had more problems with your replacement 160?

Only the people with issues are posting here. How interesting. The thread is being viewed by everyone on the planet. I wonder why no one from Wren has chimed in here. As for the strength of the blade. How is it that this motor has a propensity for blowing comp wheels like no other and we are going down the stronger blade route. Someone who owns one of these things ought to lengthen the intake using a makeshift shroud and see if it clears up the problem. I don’t own a 160 and was thinking of it but not now. There are many motors out there that I can trust and I don’t have to worry about ludicrous things like blades coming off. Jojet, if your observation is correct that the blades shed at 112k then this thing is a junk pile and Wren’s handling of the meltdown is no better than jetjoe. The motor should have been recalled at no one's expense but their own.
.

No, it was another Wren 160.turbine. I had bought two of them at the same time. The problems were not connected to the compressor, or turbine wheels.

Perhaps some of the people posting above should bear in mind they are hearing only 1 side of the story and that from someone with a grudge, there are 2 sides to every story, I don't know what the other side is but I expect it would put a very different slant on it. I expect Wren do not come to internet forums in order to avoid arguments.
As to those who speculate about the intake, unless you are a professional turbine designer with access to highly complex empirical and theoretical data, you are just speculating bollocks.

I posted a response a few months back and looking at the picture that Jacojet has posted. I am more sure of what I posted now more than ever. It is very simply "blade creep" I suspect that the metal in the compresssor is not of a strong enough alloy to prevent creep. It is evident that you can see compressor case fretting from the compressor blades contacting the case. What Wren needs to do is go with a stronger metal such as Titanium etc. As I stated earlier the owner of the engine needs to take a feeler gauge and get a measurement between the compressor blade tips and the case to ensure there is clearance. In essence if the clearances are too tight and the compressor blades touch the compressor case at speed they are going to drag and eventually you are going to have liberation of some blades.

I am an A&P and we had a similar problem years ago when the first versions of the PT-6 came out. During trend analysis an engine over time is supposed to degrade in performance. The PT6 engine (1st version) would during trend analysis get stronger through it's life cycle. What we found was the compressor blades had creep and as such we had a few "FOD" events. Same thing here is happening.

Now it is up to Wren to get this sorted out or not.

Regards
Glenn Williams

I looked at the pics and speculated that there could be an intake issue. I work on turbines and there is a lot of data here especially in the pics to suggest possible intake issues. I don't see much to suggest it is not. I asked what the diamater of the wheel is. I would also like to know what the depth of the throat is because it looks shallow but I doubt anyone will reply with dimensions. As for the Wren 160 CNC compressor wheel, I had one show up on a nexus (simjet). I dont see simjets blowing comp wheels... The intake is substatially deeper on those so I would start in the area of the intake. It makes the most sense.

A. Fioretti

Harry C,
I might agree with your statement that people may be speculating , however its very unfair that you say that this whole episode is only about "someone with a grudge".
There are about 35 compressor failures reported on this forum , all Wren160.
I've had 2 failures at 112K RPM , the turbine has never got past its first service interval, failure has been identical in both incidents.
The first time the broken compressor was replaced under warranty with yet another defective compressor which ran for sometime and failed again in the identical manner.
Wren knew at that time that they had an issue with the compressor.
If Wren can defend themselves they should !
All the reported incidents on the 160 are factual , are you trying to wish that away like Wren would like to ?
Wren had every opportunity to sort it out or even give a rational explanation and they never came up with the truth either personally to me by email or on a public forum.
So when do you expect to hear Wrens side of the story ?
The simple fact is the 160 was/is a defective design.
However you are right about one thing though , there IS only one side of the story & that is about the guys with broken turbines , there isn't another side to it.

I don't have a grudge. I think this is very enlightening reading. These engines are what ... close to 3k or more. It is not chump change when you look at it and reading this I see facts with dates and names and pictures to substantiate claims to back up the victim’s argument. On the flip side I see conjecture and mockery on the part of any defense. If I were a judge, i would have some very stern questions for Wren right now. What about intakes. I come from a world of engineering and math and there is plenty of comparison data here to make a case for trying a new intake. To argue this is pathetic. If it does prove to be an intake issue, it would be cheaper and easier to replace an intake than replacing the existent comp wheels with CNC parts. And if it proves not to be, then try something else until you resolve the issue. There are a dozen manufacturers of the same type of motor. They all differ just a little bit but none shed thier comp wheels... it ain't rocket science...

I will measure when I get my hands on one that is stripped, I have checked one that belongs to a friend (who BTW is not using it for fear of it failing) and what I can say is that the top of the compressor is about 55 mm and the bottom about 74-75 mm, the throat is about 7 mm deep, measured from the edge to the top of the compressor blades. Maybe we will use this one as a experiment to see if the modified intake will work. Just need to convince my friend!

So basically the top of the blades are almost (+7mm) flush with the edge of the intake. Wow one of these engines is not like the other can anyone tell which one? If this were my company, I would be looking at this very closely to see what can be done to improve this situation. We can argue all day about what is wrong and in the end it will take a little bit of investigative analysis and some experimenting to determine the cause for the issue and a resolution. With so much animosity, the last thing I would be doing is hiding from it.

Hi,
In an earlier contribution it was questioned whether 126k rpm was too much for this engine. It was recommended to me by WREN that the 160 should not exceed 120k rpm. I have two unused WREN 160 (one bought in 2009 and the other in 2012) which were sent to WREN for inspection and upgrade. I have yet to see if this upgrade was worthwhile or not. I paid for all incidental expenses. We also have experience of a blade shedding here as well. Luckily my friend made a safe landing.

I just got off the phone with an engineer I know in military aircraft research who works with full scale engines. He took one look at the pics I sent him from this forum with the curvature of the blades (inward) and suggested that this could be flutter. Apparently there is a resonant frequency for every motor and in full scale motors there are controllers designed to avoid whatever that rpm range is altogether. Wren could either experiment with different length intakes or calculate the length of an intake needed to shift the flutter to an RPM range that is not problematic.

Sounds like a reasonable solution. I wonder why wren never thought of that? Or did they just do no research at all? Or did they try various solutions, but non of it worked? Why won't they come out and tell? It took people on this forum only 3 days to get to a possible solution, wren has done nothing the past 5 years to resolve the problem. I am willing to put this theory to the test, but wren will not repair my engine. They reckon they don't have parts for it anymore!
So how do we get wren to respond? Who will speak for them?

Surely all the complaining Wren 160 customers have just been unlucky. Wren clearly state in the advertising blurb for the new Wren 180, that the 160 was highly successful.

" Additionally, we took the opportunity to enhance the performance and reduce the overall weight but without sacrificing any of the standard Wren quality customers have known and expected. The result was the highly successful Wren 160, launched in Dec 2008".

Well, if you look at it from their side, then yes it was very successful indeed, it created a lot of revenue in upgrades and repairs! Not to mention the initial sales, witch capitalized on the success of their previous engines. Wonder how the 180 will fare?

It was a joke.