av8tor1977

My Feedback: (6)

Often times manufacturing specifications are made to take into account the realities and vagaries of mass production. If the specs are too tight, there will be too much time spent assembling and checking the engines, and often times too many rejected parts that are out of the "tight" tolerances. Both scenarios are costly to the manufacturer. In this manner, it is often possible for the end user to improve the device. Logically, a crankshaft and hub assembly running as true as possible is better than not. Is it literally necessary to go for an alignment tighter that the manufacturer specs? No. Is it better if you do so? Yes.

Another example might be Frank Bowman's rings. They are made of a better material than most stock rings, and made to much tighter tolerances. Frank likes a gap of .000" to .001". If a factory tried to work to specs that tight, there would be a lot of time spent doing so, and a lot of reject rings that were too tight. Or possibly even engines that had rings too tight or broken sent to customers. So the end user can buy the better quality ring from Frank, carefully hand fit it, and get a nice performance boost and overall nicer handling engine; better than new....

With modern CNC machines, it isn't as easy or obvious to improve upon what the manufacturer provides us, but it is in many cases still definitely possible.

AV8TOR

dirtybird

My Feedback: (5)

Frank does exellent work. His rings are top notch. I havew several engines with them. But I never noticed any sibnificant difference in the way my engines ran.Do you have test data that shows otherwiswe? .

Cyberwolf

My Feedback: (4)

Dirty bird you need to do some testing for yourself and not proclaim to know things you don't. I for a fact have ran engine's with an out of align crank before and after straightening to find an over all improvement in both the smoothness of the engine and and RPM gain. Maybe not much but noticeable. 2-400 RPM on a gas engine is quite a jump in my book. So you do as you wish ,as for me I will give back a customer a straight crankshaft assy or explain why I can't. If you had ever built a high performance engine from the ground up you would have a clue as to what I am talking about and a back yard hopped up 350 dosen't count.
As far as Franks rings go, I have been making pistons for the mintor line of engine's and replacing there rings with Franks, I just assembled a 33 with a new mintor ring which did not have the compression to finish pulling thru the comp stroke on compression let alone have any prop bounce between strokes even with oil. I added the Bowman ring and low and behold the engine has so much compression you need to use a rag on the prop hub to turn it over by hand. And again by all means there is an increase in RPM's . If you knew something about the working's of a 2 cylce engine you would know they use compression to make power, yes there is port timing and other things, but the main factor is compression and the more comp the more power. It may not always be in a raise of the RPM's
and torque is a major factor also. To be honest I have seen and increase in RPM's 1-200 at a minimal. So go right ahead and shake your planes apart and loose power It make's no never mind to me. But keep this in mind there has never been an engine made that can't be bettered if the correct things are done to it.

You keep yapping about the .003 the factory uses as a tolerance, sure it is not much ,about the thickness of a human hair and run in close quarters an untrained eye won't notice anything is wrong. But lets extrapolate that out to say 3 foot and even an untrained eye can see the wobble. Your some sort of Mr wizard so do the Trig and see for yourself.

bradysfree

Cyberwolf. Did you ever receive any of the emails I sent you?

Cyberwolf

My Feedback: (4)

Yes I got one this morning .

speedracerntrixie

My Feedback: (29)

I'm sure there is a difference. I do things in regards to airplane trimming that to some would be considered over the top. If tinkering with an engine is considered part of your hobby and you enjoy it then who are we to tell you it's not nesessary. I do agree that in production mode there has to be compromises. Otherwise the end result although better would have to high a price point to be competitive in market. Then again, if a bone stock DA 150 were good enough for the TOC guys, I suspect it is good enough for me.

dirtybird

My Feedback: (5)

Cyber, I asiked why would you would sped the time to lower the runout to 0.0001. If yo had said you think its better I would let it go. But you said I must be mentally deficient and the factory is all wet.
I dont know a lot about engine design, But I have a friend that is a mechanical engineer,and he tells me you can go so far and going any further really doesn't help. I suspect DA has found that point because there are thousands of their engines in use.
If you know so much why don't you put it in use and design an engine. We could use a bit more manufacturing in this country.

Cyberwolf

My Feedback: (4)

*LMAO* DUh!!!!!!!! where have you been read um and weep
http://www.rcuniverse.com/forum/gas-...win-60-cc.html
The twin was made a long time before DLE came out with there's

http://www.rcuniverse.com/forum/gas-...ml#post9213420
I made 3 of these and still using two of them today. The other is brand new never ran in the box.

Ask your ME friend if he has ever heard of Balancing and blueprinting an engine *LOL*

Cyberwolf

My Feedback: (4)

Now can you see why i won't and don't share my knowledge!!!!!!!!!!!!!!!!!!!!

dirtybird

My Feedback: (5)

I note the twin post id 2 years old while the single post is more than 5 years old.
Have you sold any? If so what is the price?
I am sure my friend knows all about blueprinting.He used to be involved in auto racing. He was the one that told me it was not worth the effort in racing anyway.
I really don't care if you share your knowledge..

1QwkSport2.5r

I've found many engineers I've ran into online and in real life are full of intelligent hot air. They are incredibly intelligent, but so persnickety and nitpicky, it's enough to drive a normal person nuts. The problem with many engineers is they will find any possible fault and then create a whole scenario about that fault(s) and why it won't work optimally or why it won't be ideally perfect. If one is capable of getting .0001" runout, why would you not go for it? If .003" is 'good enough' but .00001" is better, why would you not strive for better? That'd be like buying from China instead of Japan because China is 'good enough'. Get over it.

closetguy

My Feedback: (13)

there is always someone that is going to find fault with anything that someone may do.
and even more so when they are setting behind a computer.

w8ye

My Feedback: (16)

+1

captinjohn

+2

dirtybird

My Feedback: (5)

My now we are after engineers.
BTW if you read cybers links,he gets a lot of his parts from China.
Also I can remember when Japans products were considered junk

speedracerntrixie

My Feedback: (29)

One mans junk is another's treasure....LOL. Hard to believe this thread has gone on as long as it has how sensitive some people have been. To the OP get your engines fixed in any manner you choose and go enjoy them.

1QwkSport2.5r

I'm not going to quibble with the details, but I will say that I'm not one to throw something away to buy something new if it can be fixed nor will I go with the option of 'good enough' (.003") if someone can do better for the same or reasonably close to the same money (.0001"). That is if there is no other option. I know I am not alone on this subject either.

Bringing in second hand "expert" information does little for a forum based mainly around opinion. Most of the people in the engines forums are all experts in one way or another and have far more experience than I do, but I don't by the "if the factory says so then that's that" type of mentality. I equate that with the throw away mentality. Ignorant rant over. You are now returned to your normal intelligent forum conversation.

captinjohn

Oh...what is the name of this thread. Here it is! Repair bent or twisted crankshaft. DA 150

sensei

It's a machinist/perfectionist thing, you hold as tight a tolerance as you possibly can. If you are blue printing an engine then this would be just one of many upgrades you would perform above the manufacturers standards in the ultimate effort of the highest desired HP being delivered as smoothly and reliably as possible. I think this behavior of striving for excellence falls into the category of knowing one has performed a job well done, or going above and beyond to achieve perfection, or if you are going to step up to the plate then you are certainly going to swing for the fence. At least that is the way I see it.

Bob

Cyberwolf

My Feedback: (4)

Last post to this thread, all I can say if anyone of you had ever seen a crankshaft in the lathe that was twisted out the total .003 and see just how bad things are, there would be no argument over if it close enough or not. It is hard on the bearings the piston can't track correctly as well as the ring, it is out of balance.
No it is not just a Machinist thing at all, it is making something correct and to run true.
Let me ask this , we all know what an out of balance tire feels like, so do you say well that's good enough because it only shake's between 65-70 then quit's???? Well you have the very same deal with the crankshaft being out of align. One counter balance is ahead of the other which throws the engine out of balance, and like I said sometime's is more than a man would think.
As far as a person only going so far and doing anything more won't make any difference, well if that is was the case we would all be living in the stone age and carrying around fire on a stick. Allot of this enhancements don't make sudden changes in RPM gains or prop size, So doing one may not change anything that is noticeable but do say 10-15 change's and the end results will amaze a person.
Gone!!
Everything that has been made or built can be made to perform better in some way or another.

speedracerntrixie

My Feedback: (29)

Cyber, I am not doubting what you are saying at all. I agree that anything can be made better and now that I am aware and have been reading your posts you are more then qualified to do this work. Dose this mean that everyone who has a bent or twisted crank should send them to you? Do you have time to straighten say 20-30 cranks a month? What type of warrantee would you offer? I suspect that you really are not interested in such a venture, please correct me if I am wrong. Personally I have owned 3 DA 150 engines and as an upper level IMAC competitor ( 2006 SW region advance class championship runner up ) I have logged thousands of flights with them. To date I have not had a bearing or crank related failure. That being said, if I had to pull the engine for bearings or it suddenly started vibrating more then what I was accustomed to you would no doubt come to mind. Outside of that I have to say that as someone with high standards for his equipment I have no complaints about the way my current 150 runs.

w8ye

My Feedback: (16)

I purchased a beat up G-62 from the Internet that I found to be relatively unused on the inside.

Cyber Wolf straightened the crank for me. It turned out to be a very nice, like new G-62 with his help.

He helped me through several issues with the ignition and different components.

sensei

All I meant by it is a machinist/perfectionist thing is the simple fact that I currently have 13 machinist that work for me now, and each and every one of them on their own namesake do everything they can to obtain perfection every day. Just the way it is...

Bob

dirtybird

My Feedback: (5)

Did the OP get his crank straightened?

speedracerntrixie

My Feedback: (29)

Not sure I would have worded it like that LOL