R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 04-20-2010, 04:34 PM   #1
Tech Rookie
 
Join Date: Aug 2006
Posts: 5
Lightbulb Dangers of cooling?

Hey RC Tech!

Sorry to ask a potentially stupid question but:
we all know about an overheating engine, but what is the danger of cooling a nitro engine (beyond the obvious glow plug failure)? how cool can you go before, assuming the glow plug is actively powered, you either witness a large drop in power output or another sort of failure that makes running the engine extremely inefficient?


The reason I ask this question is because I plan to use peltier junctions and an additional heat sink/cutout to allow for a leaner engine and to use waste heat to recharge a battery(and yes I understand that a peltier junction requires cooling on one side + heat on another to maintain a temp gradient and generate a current).

Lastly, approximately what percent of the nitro fuel's potential energy is actually converted to KE and heat through the engine (individually). There are ways of finding this out, but nothing beats a racer's experience/knowledge. Is there a place to find detailed specs on popular engines, such as approximate fuel consumption at stock tune/temp over time/efficiency in terms of actual data?

Thanks for the help, Alex

P.S. I really hate being on of "those guys" with overambitious projects and high expectations, so I'll come clean and say I don't expect this thing to race, I'm doing it more for the novelty of energy recovery via thermoelectric generation. hence the post on r/c tech. And who doesn't like not replacing those damn receiver packs?!
computeralex is offline   Reply With Quote
Old 04-20-2010, 05:43 PM   #2
Tech Elite
 
Join Date: Mar 2009
Posts: 3,657
Trader Rating: 5 (100%+)
Default

Quote:
Originally Posted by computeralex View Post
Hey RC Tech!

Sorry to ask a potentially stupid question but:
we all know about an overheating engine, but what is the danger of cooling a nitro engine (beyond the obvious glow plug failure)? how cool can you go before, assuming the glow plug is actively powered, you either witness a large drop in power output or another sort of failure that makes running the engine extremely inefficient?


The reason I ask this question is because I plan to use peltier junctions and an additional heat sink/cutout to allow for a leaner engine and to use waste heat to recharge a battery(and yes I understand that a peltier junction requires cooling on one side + heat on another to maintain a temp gradient and generate a current).

Lastly, approximately what percent of the nitro fuel's potential energy is actually converted to KE and heat through the engine (individually). There are ways of finding this out, but nothing beats a racer's experience/knowledge. Is there a place to find detailed specs on popular engines, such as approximate fuel consumption at stock tune/temp over time/efficiency in terms of actual data?

Thanks for the help, Alex

P.S. I really hate being on of "those guys" with overambitious projects and high expectations, so I'll come clean and say I don't expect this thing to race, I'm doing it more for the novelty of energy recovery via thermoelectric generation. hence the post on r/c tech. And who doesn't like not replacing those damn receiver packs?!
very strange. I was thinking about this today at work. About the potential energy of nitro and how to make it the most efficient. I was thinking more along the lines of something other then nitro methane. Maybe propane? acetylene? nitroglycerin's? how bout liquid oxygen and hydrogen i mean something really explosive, so you don't have to use as much.

I even thought of a way to make a pneumatic powered motor
__________________
"You are not understanding the fundamental principles of my fragmented personality"

Mugen
dreaux is offline   Reply With Quote
Old 04-20-2010, 06:01 PM   #3
Tech Addict
 
draggin87's Avatar
 
Join Date: Oct 2007
Location: Englewood, FL
Posts: 605
Trader Rating: 32 (100%+)
Default

LOX and petrolium do not mix!
__________________
Dialed Hobbies~~~~VP-PRO~~~~FZRC
Serpent 811 2.1, O.S. Speed XZB.
Serpent SRX2 MM, Tekin RS, Trinity D4 17.5 Certified

Scott Blaney
draggin87 is offline   Reply With Quote
Old 04-20-2010, 06:13 PM   #4
Tech Rookie
 
Join Date: Aug 2006
Posts: 5
Default

Quote:
Originally Posted by dreaux View Post
very strange. I was thinking about this today at work. About the potential energy of nitro and how to make it the most efficient. I was thinking more along the lines of something other then nitro methane. Maybe propane? acetylene? nitroglycerin's? how bout liquid oxygen and hydrogen i mean something really explosive, so you don't have to use as much.

I even thought of a way to make a pneumatic powered motor

Well, no trouble getting air into the chamber if your already using liquid oxygen!
and on the nitroglycerin front.... hey, it's still 'nitro'

in the meantime i'll keep trying to get accurate measurements of total energy released during combustion to decide if a peltier is even vaguely useful in terms of recovery (it would recover like 8% of the heat energy released at an absolute MAXIMUM, more like 3% in reality, assuming 80% energy from fuel in heat and only 3/8 of that heat recoverable with 10% efficiency).
computeralex is offline   Reply With Quote
Old 04-21-2010, 01:47 PM   #5
Tech Rookie
 
Join Date: Aug 2006
Posts: 5
Default

Still no word on the original question- how cool can the engine get before it becomes a problem?

Thanks, Alex
computeralex is offline   Reply With Quote
Old 04-21-2010, 01:58 PM   #6
Tech Master
 
fatdaddy's Avatar
 
Join Date: Nov 2008
Location: Temecula, CA
Posts: 1,614
Trader Rating: 4 (100%+)
Default

Quote:
Originally Posted by dreaux View Post
very strange. I was thinking about this today at work. About the potential energy of nitro and how to make it the most efficient. I was thinking more along the lines of something other then nitro methane. Maybe propane? acetylene? nitroglycerin's? how bout liquid oxygen and hydrogen i mean something really explosive, so you don't have to use as much.

I even thought of a way to make a pneumatic powered motor
+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
__________________
HPI Racing - Hot Bodies - D8 Army!
**Team Terribles** (Answer RC, Fastlane Graphix, Caster racing, M2C Racing, and Dialed Inc!)
fatdaddy is offline   Reply With Quote
Old 04-21-2010, 02:13 PM   #7
Tech Apprentice
 
Join Date: Mar 2010
Location: England
Posts: 60
Default

For recharging battery packs couldn't you just make a small alternator?
c9311 is offline   Reply With Quote
Old 04-21-2010, 02:14 PM   #8
Tech Master
 
pickle311's Avatar
 
Join Date: Aug 2009
Location: Austin, TX
Posts: 1,650
Trader Rating: 31 (100%+)
Default

Too many variables to give an accurate number. The main factor is thermal expansion. If too cold, the components aren't expanded enough. That will create more friction and excessive wear. To get the number you want, you need to know the exact makeup of the internal components and their expansion rates. What type of metal is the piston, is it CNC, cast, forged? Now you have to answer the same question with the sleeve, crank, case. Don't forget about the metal purity too, that has a major affect on thermal expansion. Just pulling a number out of a hat, anything below 180 would be too cold for optimum performance. But every motor is different. There's some that will run great at 180 and others that will run like crap.

Now also keep in mind that you can't compensate for excessive cooling by leaning your motor to keep the temps up. When you lean the motor, you are also reducing the internal lubrication. By doing so, you have just recreated the same condition as a overheated motor at a lower temperature.

I'm all for innovation and pushing things forward, but I'd say to not waste your time trying to reinvent the wheel. These motors are simple in design and there's no reason to complicate them. They are extremely efficient for what they are. Sure you could probably get a little more out of them, but at no real benifit.

Either way, have fun and I'd be interested to see the outcome.
pickle311 is offline   Reply With Quote
Old 04-21-2010, 02:18 PM   #9
Tech Fanatic
 
off road god's Avatar
 
Join Date: Oct 2008
Location: chattanooga,tn
Posts: 976
Trader Rating: 13 (100%+)
Default

Quote:
Originally Posted by computeralex View Post
Still no word on the original question- how cool can the engine get before it becomes a problem?

Thanks, Alex
You have to realize that too cool an engine temp can cause more damage than too hot at times.
ABC...aluminum,brass and chrome. They all expand at different heat levels. If the expansion doesn't take place the you get excessive wear...early engine failure

You need to be around 200 degrees...but for optimum power from the engine the tune may take it higher...

Being a racer...I'll charge my pack.
off road god is offline   Reply With Quote
Old 04-21-2010, 06:43 PM   #10
Tech Rookie
 
Join Date: Aug 2006
Posts: 5
Default

Thanks for the answers, I'll keep that in mind (and use a cheap engine to test on)

I'll probably mix some extra castor and synthetic oils to handle lubrication if temp ends up dropping dramatically

Hope to have some success to report soon enough, Alex
computeralex is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
solder batteries axel Electric On-Road 15 02-23-2005 08:26 PM


Tags
cooling, electric, engine, heat sink, tuning


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 03:10 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net