nitro joe

My Feedback: (2)

With all the pseudo hop-up analysis,"Mater of fact" statements going on in another thread,I felt the following link should be re-posted.Some of the lurkers among us, may be unsure with some of those claims presented as fact.These folks might like some alternate general high performance/tuning information to apply to there own engines.


Here is one book,while somewhat dated,is a pretty good "two stroke" treatise.The late author was mostly held in high regard as a tuner/author.

Take a look at the other pdf's on that page too.

You'll prolly need a basic Pdf reader to see it.This is the whole book...free of charge
http://www.edj.net/2stroke/jennings/


Google books also has a nice "free" on-line selection of reading material on this subject,to gain futher prospective.Some are just snippits,some are whole sections.

An example would be:
http://books.google.com/books?lr=&nu...G=Search+Books

av8tor1977

My Feedback: (6)

That book by Jennings is a good one. I've read it several times over the years. He gets a bit technical for some people, but he sure knew what he was talking about.

AV8TOR

richg99

Nitro...nice offer. Is his widow or family still around? Wouldn't it be proper to offer to send $5.00 ( the original cost of the book) to them if one downloads it? or, is everyone gone?? Do you have any addresses? thanks and regards Rich

w8ye

My Feedback: (16)

Maybe some money to the site that posted it too?

Ram Jet

Thanks Nitro, I have a PDF copy of this but it's missing a few pages. When I get some time I'll see if this copy is more complete. You seem to be pretty techy. Having read Mr. Jennings overview of the design and function of "tuned pipes" or, more properly, "expansion chambers", do you think these after market suppliers are really selling a well designed expansion chamber for model engines?

Bill
Moderator changed formatting of post

buck1856

My Feedback: (49)

Theres a paypal addy to donate a few "bucks" as the person asks to help with the bandwith.Im going over there to download it right now and donate.

Ram Jet

I think you are right.[sm=red_smile.gif]

Bill

nitro joe

My Feedback: (2)

rich:
The site with the Jennings material is the result of a Google search.It was also
posted here last year in this forum.Contact the site owner.
I've owned my copy since the late '70's. It still finds it's way into the "library" from time to time...


Ram jet:
Jennings pipe formula is getting pretty old in the tooth now. 35+ years...
Tons of modern software out there now for manufactures to purchase.
All kinds of brand/design comparisons to be found on the boards,mags,etc.


Here is an interesting hot rod chainsaw forum... porting,carbs,muffler mod's,etc.

http://www.arboristsite.com/forumdisplay.php?f=9

combatpilot

Granted I havent written a book. What do I have. FAA Airframe and Powerplant licence. MASTER ASE heavy truck. MASTER ASE automitive. Plus 20 yeary experience in these industries and more mechanical ability in my small finger than most on here. You can call it pseudo or matter of fact or whatever you want but when there is a gain in power that sounds pretty matter of fact to me. I dont care if you take my claims as matter of fact or not. All I was trying to do was bring all of this fragmented information together on one page and provide my and keyword MY results to others for COMPARISON. In fact I have several times it would be nice to have other compare their results with mine and when i explain what i think a good set up would be I always start with IN MY OPINION. Does this sound like a claim of matter of fact? I was tiered of reading where there was a modification and a claim of power increase but no numbers to back it up. When asked how much of an improvement did this make they usually say i dont know it just seems to have more power.

Im sure you are a lurker. Its to bad your willing to lurk and let the rest of us spend our hard earned money and time experimenting and thinking outside the box to try and improve this engine so lurkers like yourself can take our information for free which we gladly give you for free. Its pretty sad that your knocking our efforts and disclaming us just because what we have done is not written in a book. I do undestand that some of the test peramiters ideas and technices practiced here are less than perfect. Most of us do not have the facilities to be able to do this in ultimate perfect conditions. This is why I would like some comparisons from others. I know what gains I achieved but i also know that the imperfectness of my testing it is hard to draw any conclusions. This is why comparisons from other is really important. If I am the only one that gets a particular result then I need to retink my procedure and results. Grow some balls think outside of the box and start contributing something that you have spent some time and money on and not just your half baked doubts. If you dont try it yourself you will not know. Do something usefull and give us some comparison. The only garunteed way to lose is to not try at all.

The rubber reed valve idea I had was pretty outside the box you have to admit. To bad my ignition fried so I will not know if this was a good idea or not.

nitro joe

My Feedback: (2)

touché, my mechanically well endowed opponent...

combatpilot

Thank you. It takes a big man to concede a point and I really respect and honor that. I would rather not consider myself your opponent and hope that you do the same. Although I have all this mechanical knowledge and abbility the one thing i have learned for certian is that there is always something new to learn and everyone has something to contribute.

nitro joe

My Feedback: (2)

Concede a point...? Not likely sir., merely a retort.

retort
noun, verb
Definition: (n.) a quick, witty response to a question; (v.) 1. to quickly respond to a question with a witty or insulting response; 2. to respond to someone's argument

JIMARRINGTON

I, for one, appreciate the work, time, and money that combat pilot is investing in his test and sharing his results with us. Seems to me he is being as scientific as he can with his work. I also believe it has very good relevance to the rest of us.

That having been said, I also appreciate Nitro Joe for posting the link to the book above. Also a very relevant topic to this forum.

Dont see where either should be disregarded or moved.

Why cant we all just get along

Jim

combatpilot

Ok now i know your just ignorant.

ig·no·rant (gnr-nt)
adj.
1. Lacking education or knowledge.
2. Showing or arising from a lack of education or knowledge: an ignorant mistake.
3. Unaware or uninformed.

Since you want to throw around definitions I think you need to learn the definition of touche


tou·ché (t-sh)
interj.
Used to acknowledge a hit in fencing or a successful criticism or an effective point in argument.



[French, from past participle of toucher, to hit or wound in fencing, from Old French touchier, to touch; see touch.]


I wasent saying any information should be removed and very much would like to get along. I dont think it fair either to discredit my efforts with no testing of his own to back it up.

Jezmo

This is the red text that is above the reply box. "Please resist the urge to curse, flame, degrade, insult or embarrass someone in your post. We encourage the free flow of your ideas, but believe that they can be communicated (and received) much more effectively if you keep things civil. If you have to vent, take it offline. We carefully monitor posts and will ban individuals who engage in offensive conduct within the forums. Thanks.."
The last post might be found to be degrading, insulting, or embarrassing by some. Surely we can just click the little "Block" icon (Red Hand) at the bottom of a post if we don't like what an individual is posting.

combatpilot

My apollogies i will edit as not to offend

Ram Jet

Thanks Nitro. Not trying to challange any aftermarket suppliers technical skills but it's more than just "cutting or lengthening the header pipe" as I have read here on various posts. It's even a far more involved undertaking than intake and exhaust timing. It's beyond my little brain. As far as Jenning's concepts being dated. Yes maybe, but most of "Two Stroke Tuner's Handbook" is as fundamental as gravity and a sunrise. You can't change basic physics.

Ring-ding-ding-ding.
Bill

combatpilot

I will agree with that RamJet. I really dont consider any material dated. I dont know how many times I found a concept idea or practice that I though was new only to find it had been done many years ago and somhow lost or forgoten only to be brought back and utilized again. Besides if it wasent for jennings laying a foundation what would the rest of us have to build off of?

Ram Jet

Combat, I have a neighbor who races a two cycle motocross motorcycle professionally. His bike has what I think is a remarkable design feature. It has an exhaust port valve that opens and closes with the engine RPM. Wow, the Achillle's heal of two stroke engines. Blowing fresh fuel air charge out the exhaust pipe at low RPMs. Ingenious I thought. Until I remembered Enyas with the exhaust flap that opened and closed the exhaust port in synch with the carb butterfly/barrel. What goes around comes around. "And the seasons go round and round,And the painted ponies go up and down".

Bill

combatpilot

see there ya go theres the perfect example. whats old is new again.

Nosedragger

Snowmobiles have put exhaust valves to good use for years, when it comes to engine "innovation" everything has already been done or tried before. The only difference is now technology advance in materials, manufacturing,analysis and electronic control capability have made these ideas possible to implement.
Although possible to develope performance enhancing features, applications such model aircraft given weight and size constraints, make it impractical to utilize.If you are looking for state of the art two strokes, look at outboard motors and snowmobiles.
Jennings and other authors have noted that their concepts would be easier to apply if computers were available at the time.The time area principles laid out by Jennings are valid today.Using a computer program makes time area calculations easy, several companies market software that perform these functions.

If you are looking for more in depth and "modern" material on the subject look up Gordon Blairs book "The Design and Simulation of Two Stroke Engines"

There hasn't been much published on the subject of two stroke engines in recent years except about emission reduction strategies.

Ram Jet

I love retorts. Especially cherry.

Bill

av8tor1977

My Feedback: (6)

The exhaust valve(s) you speak of.... On the Enya, (and others), it was done to keep the glow plug warm at low speeds and idle. It didn't change the exhaust port timing; just provided some back pressure to keep things warm at low throttle settings.

On the newer two stroke engines with an exhaust valve, the valve actually changes the exhaust port timing, allowing you to have a more radical timing at high rpms, and a lower, more tractable timing at low rpms. Rotax also uses this technology, among others.

AV8TOR

Ram Jet

av8 you are scareing me. You are right! Honda too!

Bill

blw

My Feedback: (3)

I just had to clean up a lot of argumentative posts and I'm not going to PM each poster as to which of your messages got the ax.

This is too interesting to let slide into petty fighting. The moderators will keep it cleaned up from arguing so the rest of us can enjoy the collection of good knowledge. BTW, thanks already to the contributors!!!