RE: Nitro Crawlers??
I myself do beleive a "Nitro" can and will crawl, and it is one of my current projects. I have posted on here about it as well as on other forums as well. The major hold up is my recent move and setting up a new workshop. I dont mean to PICK on Rockwerks but he has stated some of the things to touch on for a nitro crawler. these are my OPINIONS on the subject.
Rockwerks: these are the facts,
Mechanicalbob: and my opinions
Rockwerks: A nitro engine is designed to run at high rpm's, crawling is done at low rpm's theengnne at low rpms will jsut eat up clutch packs
the nitro engine uses a clutch to absorb shock and impact.....put your foot in front of a tmaxx and watch nothing happen
the gearing for nitro is way too high for actually crawling...to make a decent crawler with a nitro engine you wil need gearing in the 600:1 range or even deeper AND ROCK also stated electric motors used in the sport of crawling are high turn low rpm, high torque motors ( you would not run a 10 turn mod motor in a crawler)
Mechanicalbob: I do agree the Nitro engines for cars/trucks run at high end of the RPM range of things they are designed as "Race" engines. As stated you would not run a 10 turn in a Electric crawler and I agree with that. So with that said a "Nitro" crawler should not use a "race" engine to crawl with as the Electrics do not use one eather. So I what I am using is an airplane engine to start out with is a OS FS .30. It is lower in the rpm range and has a bit more torque than a "normal" nitro. One way to bring up the torque on it is to convert it to a diesel with a Davis Diesel kit and it would help keep the heat down too. Of course other means of cooling will be needed, one way is to run a belt drivin fan off of the flywheel. As for the clutch problim I dont see one. Now for the gearing, If a Crawler has a FINAL ratio of 600:1 with 2.2 tires at WOT it would travel at a rate of about.......1-2 feet a minute, quite low but a bit slow. Put in a final ratio of about 112:1 in a nitro and you would get about 15-20 feet per minute at WOT, right about in the range of a good crawler. If I rememeber right some people are use a "lathe motor" in there electric crawler and have a ratio of about 85:1.
Rockwerks: in electric crawling many things are done to make the rig more effecient
the center diff or tranny is locked........
the clutches or slippers are usually totally done away with so the multiplied torque can be used rather than absorbed
the axles are locked so all 4 wheels will turn at teh same time
Mechanicalbob: I do agree the axles do need to be locked. As for the tranny it shoulnt be locked, the reason I say this is so the "power" can be transfered to the front or rear of the crawler as needed. the clutch system is there to help the drive train from being twisted up, as with any mechanical thing torque or power will be lost.
Rockwerks: In order to make an effecient crawler with a nitro rig you will have to over come the poor clutch performannce and have direct control of how te clutch applies torque to the driveline. you wll need to regear the center trans mission from the 2:1 range to into the 600:1 or 1000:1 to be able to use the small amount of torque actually put out by the nitro engine. A quality braking system will need to be installed to hold the rig from rolling backwards on climbs and decents, this system needs to be independant from the clutch system .
Mechanicalbob: The "Poor" clutch can be takin care of by running a 4 shoe setup, with out the springs in place so there is a "faster" lock up and disengagement. Most braking systems on nitro's are independent from the clutch setup and it would not be hard to add a 2nd brake on a nitro. some of the things needed are a "mixer" from a airplane radio and 2 disk brake setups from the NTC3 road car.
Rockwerks: this is just a few of the problems that need to be addressed to turn a nitro rig into a competant crawler.
can a nitro rig be made into a quality crawler? even after all the above is overcome, and you grow several more thumbs to control the different functions at the same time............and spend $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$, it still willnot be as effecient, reliable or cost effective as an electric rig,
Mechanicalbob: Alot of the problims have been worked out in making a great nitro crawler, one thing that needed to be addresed was the fuel tank. A standard car tank doesnt like to run at weird angles so if you were to run one while cralwin you could starve your engine for fuel, to solve thise I am using a "flopper" tank out of an airplane so my truck can still run while on its lid. As for growing extra thumbs.........Still workin on that. All that would be needed in a nitro crawler is a 4 channel stick radio with a "mixer". As for the over all cost of a "nitro" crawler is about $600.00 so far. What I have for gear in my truck is a T-Maxx tranny with a e-maxx mod and reverse, TLT solid axles a OS FS .30 and a custom frame and a few other lil weird things.
Rockwerks: an electric crawler can be built for the cost of an aftermarket nitro engine
Mechanicalbob: It all depends on the aftermarket engine some will range from about $65.00 all the way up to about $750.00 or more, so it depends on what you want in a crawler. My OS FS.30 ran me about $145.00
As I stated these are my opinions on the subject and have been told about 500 times or more that a nitro cant crawl so I set out to build one. It should be done in late summer.
Steve.