The 24 Hours of Lemons Forums → The Airplane-Powered MR2 → Never before has so little power been made from so much displacement!
a "new" part has arrived:
massive flywheel, 56.5lbs, it's 15.25" in OD and 1.5" thick, no weight reduction holes at all and it saw 2800 RPM in it's original application.
i also have the matching starter on the way. it turns out it spins the correct way and this way i don't have to worry about the teeth mesh pattern.
Why is this not in the "Epic Builds" section!
Why is this not in the "Epic Builds" section!
because by the time that was a good idea there was too many people already linked to it here. i'd rather not break everyone's link and subscription to this thing.
That's not a flywheel. That's a manhole cover.
It has balanced rust holes. Cheater!!!
It has balanced rust holes. Cheater!!!
it's not cheating, it's building creatively...
Radial engines are exempt from BS laps.
now if i could only get this thing to do more than one lap! 
That's not a flywheel. That's a manhole cover.
awesome
Been a while since I was able to consider Lemons again or check out this thread again, and I have to say EPIC EPIC build!!!! :-D
I looked at your sprocket picture, on dirt bikes that kind of tooth wear/damage is caused by the chain being too loose and 'riding up' on the teeth of the sprocket. When I looked at a pic of the chain/sprocket setup, it occurred to me that what may have happened is that the shafts flexed, bringing the centers closer together and making the chain loose. That will wear out sprockets and chains in a hurry. If there is any way you can support the outside end of the shafts so this can't happen, that will probably fix your problem. Maybe make a housing with a bearing on each end which slides over the ends of the shafts?
bump
I actually *DO* have an update, I was in the shop working on it today.
I removed the old snout/chain drive assembly and reused it's flange for the flywheel mount
Then i machined the rear of the flywheel slightly to add a locating pilot and the proper bolt pattern:
then the whole thing fits!
about an inch of clearance to the transmission. 
of course, tomorrow's work looks a bit more complicated, the strut bar i welded in to make up for the removed firewall is in the way of the starter:
i just need to go a bit higher to make the starter not interfere with the number 5 cylinder.
alternately, i could use a smaller starter and not modify the strut bar:
here's a shot of the two starters. the one on the left is a cummins turbo diesel starter and the one on the right is a 2nd gen turbo MR2 starter it spins the wrong way, but there are others available in that form factor.
but i think it would be a bad idea to go with the smaller one since that's equivalent horsepower to the previous starter i used and even with the 3:1 torque increase going through the chain drive it was barely able to spin the motor 25-30RPMs. it's possible there was just that much friction in the entire system and it would be fine directly mounted there.
it also seems that as i'm running the motor, the rings are taking a good seat and sealling better and better. overall, this is good but it does add quite a bit of effort required from the starter. i can't turn over the engine by hand anymore, i need a 4ft pry bar now.
do we have an old airplane guy in here that can tell me what the locking prop nut is supposed to look like? i need a good compact solution to this problem.
last time i just mounted the fan on the prop nut to ensure it did not loosen. this isn't an option in the new configuration.
do we have an old airplane guy in here that can tell me what the locking prop nut is supposed to look like? i need a good compact solution to this problem.
last time i just mounted the fan on the prop nut to ensure it did not loosen. this isn't an option in the new configuration.
i've emailed my buddy & co-driver Paul, who is an aircraft mechanic (and actually maintains one of the few DC3/C47's still flying). hope to hear by Monday.
Marc wrote:do we have an old airplane guy in here that can tell me what the locking prop nut is supposed to look like? i need a good compact solution to this problem.
last time i just mounted the fan on the prop nut to ensure it did not loosen. this isn't an option in the new configuration.
i've emailed my buddy & co-driver Paul, who is an aircraft mechanic (and actually maintains one of the few DC3/C47's still flying). hope to hear by Monday.
awesome! thank you very much.
If the parts are actually available i would not mind spending some money to just buy them but the thread is really odd. it's got a 2.056" OD on the thread. not sure if it's just an oddball or a weird airplane standard.
if it helps, here's what it looks like:
Did you measure the thread pitch? afaik, 2 1/16-16 is a 'standard' nut.
Ext. 21/16-16 UNS 2A Max Major 2.0609 Min Major 2.0515
Did you measure the thread pitch? afaik, 2 1/16-16 is a 'standard' nut.
Ext. 21/16-16 UNS 2A Max Major 2.0609 Min Major 2.0515
sorry, forgot to mention that data point: 12 tpi
interesting, it did not occur to me that the larger sizes would be so far off from the called out size:
i don't feel so bad about having to make another nut now, i just bought a tap that will greatly simplify things:
http://www.ebay.com/itm/2-1-16-12-Threa … 329wt_1298
because at the end of the day i'm a very amateur machinist and making those internal threads last time was a bear! i know enough not to kill myself in the shop and that's probably about it.
Marc, Not sure if he has the tools and tricks you need but Nick who you are in the little email ring with lives rather close to you and has access to quite a little machine shop and all the skills needed to make cool toys.
You may want to see if he has what you need on hand.
Marc, Not sure if he has the tools and tricks you need but Nick who you are in the little email ring with lives rather close to you and has access to quite a little machine shop and all the skills needed to make cool toys.
You may want to see if he has what you need on hand.
it's alright. that's all part of the fun. i'm getting better at machining things by making this car. anybody can build a car by farming out all the labour.
so far the only thing on this car that is custom that wasn't made by me were the fuel injection cups. i designed them and a local lemon guy Aaron made them on his CNC machine.
everything else was all made on old machining equipement (ok, newer than the motor) but all old-school hand-cranked equipement.
I know it's cruel, but I can't stop laughing over Judge Sam's description of the sound of the original chain-drive setup failing as it drove by the Gingerman penalty box: "A clothes dryer full of hammers."
I missed it, because I was out in the blizzard trying to shoot photos of the Radial MR2 on the track.
I know it's cruel, but I can't stop laughing over Judge Sam's description of the sound of the original chain-drive setup failing as it drove by the Gingerman penalty box: "A clothes dryer full of hammers."
I missed it, because I was out in the blizzard trying to shoot photos of the Radial MR2 on the track.
i actually had no idea it was failing. when it did i was in the process of coasting into the pits. i could have shut the engine down had i known.
it probably broke between turn 10 and 11 when i gave it a boot full of throttle for the first time.
but there was no way to tell, being inside that thing was about like being inside a paintshaker with 5lbs of bolts
the new drive system should quiet things down significantly. but i still expect it to be a heck of an auditory experience.
I decided to cut the strut support to fit the bigger starter.
it does not have 100% engagement since the cutout in the casing to miss the flywheel is at the wrong place. no big deal, this should be enough for all the miles this vehicle will see:
then i came up with a neat trick to pre-crank the motor. you're supposed to run this motor through 2.5 revolutions before trying to start it.
first, shove this spacer in to push the bendix out:
then, put a socket on the end of the starter and turn!
i just need to make a tool that can fit in that area better than a ratchet. it makes the engine rather trivial to spin with it's 13:1 mechanical advantage.
the first test crank definitely demonstrated that the bracket won't be enough on it's own. i have plans to make something that grabs the front face and prevents the starter from bending the mount.
But the great news is, I think I overdid the starter size. the motor looks like it's turning about 400-450rpm now while cranking. That's significantly higher than my target idle of 300rpm.
also, in the name of making this thing sound less like a drier full of hammers, the alternator will be driven by a V-belt and i'm re-configuring the cam and crank sensors. the crank sensor will go to a variable reluctance style sensor with a ford Triton V10 tone wheel. the wheel should be here in a few days and i'll install it then. the cam sensor will be a bit trickier. but i think i'm going to make a custom valve cover for one of the valves with a hall effect sensor to detect when the #1 intake valve gets depressed as my sync signal.
overall, it was a good weekend!
'Clothes dryer full of hammers.' 
I would think you could put a separate ignition switch and a starter button so that you could turn it over 2.5 revolutions before flipping the ignition switch.
That's how I have to fire up my high compression dirt track motor.
All you'd need to figure out is how long it takes the starter to turn the motor 2.5 revolutions before you give it some spark.
I would think you could put a separate ignition switch and a starter button so that you could turn it over 2.5 revolutions before flipping the ignition switch.
That's how I have to fire up my high compression dirt track motor.
All you'd need to figure out is how long it takes the starter to turn the motor 2.5 revolutions before you give it some spark.
The idea of the 2.5 rev pre-ignition turnover on a radial is, among other things, to make sure the thing isn't hydrolocked in any of the bottom cylinders. Turning it by hand won't bend anything if one of the cylinders turns out to be full of uncompressible oil - running it on an electric starter will.
The idea of the 2.5 rev pre-ignition turnover on a radial is, among other things, to make sure the thing isn't hydrolocked in any of the bottom cylinders. Turning it by hand won't bend anything if one of the cylinders turns out to be full of uncompressible oil - running it on an electric starter will.
exactly. it's not for pre-lube like other motors. it's to prevent breaking stuff.
plus, with this new starter setup. 2.5 revolutions takes about less time than it takes to think "holy crap, that starter's going to eat me!"
once i get the strut bar fixed and the starter reinforcement in, i'll get a video up to demonstrate the violence of the new starter.
The 24 Hours of Lemons Forums → The Airplane-Powered MR2 → Never before has so little power been made from so much displacement!