SManMTB

The only load the question had was to see if you actually understood what tuned length is an how it works. Major fail.
You are dwelling on very strange theories but yet can't comprehend this very basic equation.

kochj

I have a question that is related to GAS engines.....

In particular, RC aircraft engines.....2-stroke premix....

Almost all have a rear carb that feeds either through a rotary or CF reeds.....
So there isn't any Schnuerle porting???

Evolution has a 26 and 35, and 40cc gas engines that are Schnuerle porting, with the carb in the front
Just like the alcohol/nitro rc car engines.....

Would gas 2-stroke engines benefit from this crank work??

Also, I have a ZDZ 40cc with a lightened crank, (too lightened as it vibrates too much)
and I was wondering if it would be possible to do some sort of insert?
Would a drilled hole with molten lead poured in work? Or would this overtime become dislodged
and wreck the engine???

This engine is a rear carb, with a rotory intake...

I am not a machineist, but I am a self taught jack-of-all trades....master of few....

The reason I asked, is that you did work on the 2-stroke snowmobile engines...

Justin...

PowerHouse RC Performance

My Feedback: (1)

Should I just tell everyone step by step how to do this and never make a dime or should I keep somethings to myself so I at least have a few tricks left in the bag to set myself up for a little success? As I said in another post, I am at work a lot of the time and can't really see or remember what was asked so that is why some questions get overlooked. I don't have to justify myself to anyone and the very few people who think the way you do are usually the biggest problems because they think they know everything and if everyone still followed by the books, we would still be riding around on 1973 arctic cat pumas with all of about 18 hp with a gas tank made from 2 bread pans welded together on leaf spring suspension. But because of people like me, we now sport genesis 4 strokes and ride on gas filled shocks and suspension geometry that handles like a wet dream. So to you, good luck with your readings and your future engine facts and maybe someday we will cross paths at the race track and share a few beers. The people who have taken their chances with me have not been disappointed so I guess I am doing something right. Take care smanmtb!

haikt

My Feedback: (11)

PH,
You have to have clear numbers that you have achived.
The answer that each engine is different and such is true bit does not represent the effect of your changes.
Please provide numbers (RPM, Speed, ect) that have been achived after the mode vs the original.
And telling people to go read another place because you are not able to answer them is not good buissnes the first couple of posts killed all the desire to get any work gone by you.
Just my 2 cents

SManMTB

Sure will.....





[8D] [8D] [8D]







.

savagecommander

very strange theories? hmmm... they seem to make sense to me- anybody else think my ideas are crazy and wild eyed? id be more than happy to discuss.


and to answer your question- i have quite an understanding of tuned pipe length. ill start off with my responce to your question about length- when port duration is increased, especially exh port, the rpm that peak power is acheived is brought up, due to larger effective port area(youll find this in jennings book) so naturally the first thought is "oh thats easy, high rpm power= shorter pipe... but the trick is since you want the HP peak to stay the same, yes the pipe would need to be longer. seems kind of strange though, its like youre building the motor around the pipe- i usually do it the other way around. lets take for instance, zen 26. 11.2mmx 19.8mm exh port- 170deg timing. this puts good power up to about 15-16k, but then drops off. so lets say my pipe is set up for an exh area of 221sq mm whicjh is stock, and 16k peak power- thats 559mm total system length, and a lead in pipe dia of 22mm- i take the exh port roof up 1.3mm to 12.5mm which should be close to 180deg, and is up to 247sq mm, and the power should be good to about 17500rpm, so well set the pipe up for that. total system length goes down to 542mm, and the lead in pipe goes up to 23mm, but fo rthe sake of low end power retention, id go right up to a one inch lead in pipe(this is also in jennings book)- now we'd also have to take into account the transfer ports, as now the exh timing is more, the exh gasses have more time to exit, so we could either leave the transfersd unmodified, OR, change the divergence cone angle to have a bnroader signal pulse,since now the transfers dont have to rely on the pipe for fresh mixture extraction out of the case, and should also help keep low rpm power up. and while im at it, id set the convergence cone angles more sharply so power would drop off quickly after the 17.5-18K mark, as these motors have bearing life issues when pushed past 18.5-19K ...... but, i guess thats all a big fail, right?

kochj

He already stated why he didn't set something like that up...


Different Dyno's, cars, spur gears ect ect............

In My opinion, a way that would satisfy all of this things would be simply, "proof is in the puding"

1.Take a car to a track
2. use stock engine that is recently broke in.
3. do 40 laps or so that is recorded with a competition lap timer...
4 Take out stock engine, replace tires, and place the same engine, but with your mods in it
5Do 40- or so laps that is recorded and compare times.....

This would be a very real deal scenario......
Off road truck would clear jumps better or onroad would get out of corners better ect.....

This is where you find out if a engine's mods are working or not....
A posted dyno would be quite easy to do.....
Even if you don't really care about it, it would sell more of your mods....No doubt!!!
Video it, and post it up on your web.......
All the naw sayers wouldn't be able to say anything negative about that!.....

savagecommander

WOW LOOK AT THAT LITTLE CRANK IN THERE!! holy smokes!!!! ive never seen that before- good thing for you, of the motor is rotary or reeded youll prolly have the loop porting youre talking about with the benifit of reed/rotary valves.

kochj

Yes....
I think the power suffers a bit, as the Evolution uses a really neat idea.
They have inserts that add bulk but not weight, and helps stuff all that
gas/air into the ports much better.....
I may just go back to the stock crank though.....

supertib

My Dremel is bigger then your Dremel !

everyone here with first hand experience modding engines please raise your hand !

SManMTB

Aye

[sm=thumbup.gif]

savagecommander

[sm=thumbs_up.gif]

SManMTB

Over and Out.
Carry on.

mimirc4me

My Feedback: (8)

i see that aircraft engines now have fuel injection .... can that be done for a race engine for an rc car and would it bild more power and make it easyer to start ?

SAVAGEJIM

PHRC, you have a dremel talent that I totally envy. I cannot reproduce those crank counter weight cuts you do, and I have been modding nitro engine on a hobby and personally level for a couple of years now. I say keep up the good work even though you might not be versed in every single minute reciprocating engine terminology. And from reading your posts, I think you have the concepts in mind even though you dont use the industry engineering terminology.

SMan, no one is going to deny that you are a licensed professional engineer, and that in itself is an accomplishment. So guys, he is not full of it, and do recognize that a licensed PE is no easy accomplishment as you have to jump through several hoops [the first is you MUST hold an ABET accredited engineering degree, have passed the NCEES' EIT test at about the time of graduation (shortly before or some time after obtaining a degree), and have no less than 4 actual years of engineering experience before the NCEES will even consider you to take the PE test]. Even though he is an EE, he does know this crap even though this stuff is mostly what a mechanical engineer would spend his learning on. So, what he has said is fact and not opinion; as a matter of fact, it is educated facts.

SMan, I must say that I do believe that PHRC IS referring to the Trapped CR, because he always talks about exhaust port relation as far as moving it up or down. But I also must say you do bust people's balls alot in RCU because you know your background, education, and experience. So much so that you walk with a chip on your shoulder. For all the years I have seen you posting in RCU, I have always seen this pretense from you.
You really need to step back and begin to post with a more helpful and educative attitude, not the "I know more because I am a PE." Everyone sees your pretense and takes it negatively. Even PHRC saw this pretense in your second post in this very thread. Based from your question asking, it really looked like you were trying to give him just enough rope to hang himself (that is what is meant by asking loaded questions; to set him up to fail so you can prove yourself right). Please forgive him because he does not know that trapped compression ratio is exactly what he is saying: this being based on the position of the exhaust port height and the remaining cylinder volume to TDC. Also, please do not rag on him because he does not know a lick of finite elemental analysis (heck, how many people in RCU can even do anything with any sort of differential equation?).

SMan, you know your stuff very well, there is absolutely no denying that, and you have SO MUCH information that can help ALL OF US understand so much more about our beloved RC hobby. I beseech you to consider how you come across when you pass on information. Alot of times you might not intend to come off hard as people perceive you to, but it all has to do with the way your posts sound. Do take it easy and when you reply, really consider diplomacy, then people will really want to learn your knowledge.
Forgive me for sounding hard, I am saying it the way I see it. You are a very knowledgeable guy and your engineering information is spot on (I personally cannot find any fault in what you said here). And this knowledge is 100% applicable to our discussion, what happens inside the engine for given mods. We can learn so much from what you know.

Buzz Kill

My Feedback: (220)

I have done a lot of these modifications as well using my CNC mill. They work very well and are worth the effort or $$!

savagecommander

donno how thatd work- usually the 4 strokes are FI....

PowerHouse RC Performance

My Feedback: (1)

Thanks SavageJim, I appreciate the kind words. I agree, I have no idea why he has so much to prove. He could make everyone better if he would just relax and enjoy himself a little. As far as the grinding, it is all by hand, no machines what so ever. As far as all the lingo, I went to school also but a totally different type of schooling. All my of knowledge and experience was learned over years of designing and building engines for Polaris along with some military background with helicopters.

You are right, i may not have every single term memorized and every equation memrorized but I have the ability to just look at something and know where I need to go with it. The best way to compare it to is like a painter or a tatoo artist. You can stare at a picture all you want and try to draw as you see it and unless you have that particular talent to just be able to take your visual picture and get it down on paper or even someone's body part exactly how you see it in your mind, that's just pure talent.

Porting is a similar but different talent. For whatever reason I can just make the cutter do exactly what I want it to do and the cuts are very symetrical, even and smooth. No chattering, walking, uneveness etc. You can have that talent and not know what to do with it and the years of background I have designing, building and racing on a professional level gave methe ability to be able to look at the engine like it was a picture, visualize what it needs to get the desired performance and then just lay it out on the engine itself. People ask me all the time how doI do it andI can't explain it. It's the same thing with artists of other trades, they all say the same thing, "I don't know, I just do it".

Ican look at pipes and know what they are going to do withouteven running them, I can look at anengines layout andI just know where togo with it without even doing all the formulas to find out what it has for case volume, flow characteristics etc. I can race tunemost engines in about 2 minutes and havelost count to the amount of times I have taken someones engine who wouldn't run at all andthe person spent hours trying to get itfigured out and I had it ready to hit the track inside of 3 minutes and allI get is this smile and a half of a chucklefollowed by the phrase " I cannotbelieve you just did that and how did you do that". My answer is still the same, "I don't know, I can just listen to the engine and it tellsme whatit wants" I have enough experience tuning all types of engines over the years that I developed a good tuners ear and I have raced aganst people who have twice the racing experience and still can't tune engines the wayI can.

Alot of people can tune but they use tricks like the pinch testto judge bottom end delivery etc. I don't use a temp gun, never had to use the pinch test etc. I just have the ability to listen to what it is telling me and i just do what I have to do to get what I want out of it.Sorry for the rambling but I guessI had to say this just to say that even though I don't have every term and equation memorized, doesn't mean I can't build a steller engine.I have studied and tried my ass off for years to be able to learn how to draw and airbrush because that is something I have always wanted to do and here I am years and yearslater and I draw and paint just as awful as i did when I was 5 lol! i just don't have the ability to drawand paint like that and thats why i pay the guys who can and I do it without questioning their background or education.

If they can doexactly what I want, I don't personally care where and how they learned how to do it. I also envy those guys who can do it because there is definatelygood money in it and great personalsatisfaction in being able to do that sort of thing. I used to sit in classin 7th grade and watch this kid that sat next tome draw comicbook characters like it was his job and I was just mezmorized by it and I started to try to learn to do that and failed miserably.

SManMTB

It's all good. It's an internet forum and not a novel writing competition. I always speak from MY point of view and when I am wrong I am wrong, that's it...
People ask me a question and I always try to give an answer based on fact an/or experience and will expect the same in return.
I have absolutely nothing to prove and don't need to. It's simple questions and answers with discussion. I get called out on stuff all the time so what is the big deal with a 'loaded' question? It's not loaded at all, just back up your claims.... The same goes for the business owner.
OK.... over and out. This thread is done.
cheers,

Brent Davis

PHRC, nice looking crank mods. I gotta ask though, do you do any drag modded engines and if so, does any of your customers report back on ET or performances at the track? I run in the IMDRA drag race series now and there's only RBmods, Nitrodynamics and Litespeed Engineering that has any engines that guys are winning with. I'm always looking to see what else may be available to race with.

PowerHouse RC Performance

My Feedback: (1)

I have done a bunch of drag engines and I get the reports that they are the ones to beat at the track since they got the engine back but no real official numbers as far as what they were running before and after they got the engine back. I did have one guy from long island send a GRP .28 to me that he said was decent off the line but fell flat on top and they race 600ft. I had to clarify that that distance was correct. He verified it as grudge racing and they run 600 ft. I was like holy smokes that is pretty far of a run. He told me he always got beat by the same guys every time and he wanted to show them and he sent it to me and the following week, he called me on monday and thanked me up and down for the engine work because he went out and smoked everyone including the 3 or 4 guys that beat him regularly. No numbers though. I was hoping he would get back to me with some but nothing yet.

There have been several cases of that where they go out and run them and report back with great success but no real numbers, just guesstimates on what it was doing before and after but they said the after was night and day so I never really pushed the issue because as long as I keep getting the calls and emails of guys saying "I saw so and so's engine run and now I want one", that's all I care about. As much as i would like to get every motor and car out there to test with, it is just way too expensive and time consuming to do so I have to rely on some feedback from people. Some have requested videos and that is something I could do and it may be in the near future. I am redoing my entire website also and in there i will have alot of other products and information of what I do and sell including the Novarossi line of engines, TKO bearings, nitro engine pre heaters, custom cooling heads, t shirts, hats etc. I even have beer and soda popcozy'savailable to helpkeep your drink coldlol.

bikeracer

A lot of interesting reading here,but I wish your long posts were broken up into paragraphs more..it makes it easier to read and follow on a screen.

.

HerrSavage

PowerHouse RC Performance

My Feedback: (1)

will do bikeracer, sorry

Brent Davis

O.K. Well if you are ever interested in having a .21 engine that you drag mod tested in our 132' national event track lengths, send it my way. 600' is foolish and is almost a death sentence to the engine IMO BUT if there's guys out doing that, then so be it. At ALL of the IMDRA drag races the ET's range from 1.6's @83 MPH to 1.9's @70 MPH in Pro-Mod. Like you said the hear-say aint gonna cut it. The real #'s is what is important.