Ramblin' Rover Bait [PEDANTRY]

"Rusty Vandura - www.tinyurl.com/keepoppo" (rustyvandura)
03/21/2020 at 11:16 • Filed to: None

Good morning. This is the GM 702 CID V-12 known as the Twin Six . GM produced these in the early sixties. Something like the lowest power-to-weight ratio engine of all time. But here’s the thing: 250 horsepower and 585 pound-feet of torque. So this engine can twist the heck out of its crank, but can’t do all that much work ? Like you could pull an aircraft carrier with this engine, just not very fast? Do you mind giving me a Physics lesson on this?

DISCUSSION (22)

MM54 > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 11:23

I do like me some Twin Six.

Think of it this way (it is a truck motor after all)

The truck hosting this will do 0-60 in x seconds with no payload. We then put a few hundred pounds of weight into it and it does 0-60 in x+1 seconds. Now we take a bike that also does 0-60 in x seconds, and put a few hundred pounds of weight onto it. It now takes a couple minutes to make it to 60. That’s torque.

Edit: reading this back, it isn’t a very good explanation after all, but I tried.

MultiplaOrgasms > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 11:31

Its a gasoline semi truck engine, one of the very last of its kind. Tops out at around 2500-3000rpm. Has four cylinder heads because it is based on a 351 ci V6. In actual fact, the engine has very oversquare dimensions, so if one were to do some custom head, cam, and intake/exhaust work one could really wake them up, of course there is still the issue of weight

WilliamsSW > MM54
03/21/2020 at 11:34

It makes sense though. OTR tractors I think are in the 400-600 HP range even now. But torque is in the 1500++ range.

DipodomysDeserti > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 11:35

Work is just force and distance. There’s no rate component. Power is the rate at which work can be done. Torque is technically rotational work, which a vehicle translates into linear work through the driveline. So that engine can do a lot of work, just really slowly.

My ‘66 GMC originally came with the V6 that the V12 was based off of. First American produced V6.

Dakotahound > MM54
03/21/2020 at 11:35

Actually, that was a good example. Also, remember, you can generate torque with gearing or leverage . If you take two vehicles with the same engine, and install two different gear ratios, the vehicle with the larger gear ratio will have more torque. In the same way, when tightening or loo sening a bolt, using a longer wrench handle will result in more torque. Inside an engine, the crankshaft shape can influence torque .

RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 11:37

I always thought this was a decent explanation.

gmctavish needs more space > MM54
03/21/2020 at 11:42

I think that works. Same as when people say the diesel version of whatever truck was worth it because it feels the same whether it’s pulling a trailer or not

Rusty Vandura - www.tinyurl.com/keepoppo > MultiplaOrgasms
03/21/2020 at 11:47

There are people who build those. And some are still in use in industrial settings.

Grindintosecond > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 11:52

Lot s will talk with math and figures, but simply put, it’s torque in that gear and how deep into rpm can you have any torque to get speed. The NSX could out accelerate slightly more powerful cars at the same weight cause it could hold a value of torque power to 8k (vs. 7k) rpm and had better mechanical advantage as a result. Bikes are the same. Light weight motor at a bazillion rpm will have speed.

Think the other way. This 702 was built for pure pulling. Displacement is King for pulling because it makes torque from displacement rather than rpm. That means torque at idle power and enough for a trailer. We can make a car engine do it, but the g earing would be so crazy to multiply that torque you’d need thirty gears to get anywhere.

Its aout pulling things starting from zero.

Today tractor trailers have a tonne of gears, big torque only, and if you’ve seen them try to pass another on a hill for miles, they’re foot is on the floor. They physically can’t go 120 when loaded.

Rusty Vandura - www.tinyurl.com/keepoppo > DipodomysDeserti
03/21/2020 at 11:53

So that engine can do a lot of work, just really slowly.

That’s the conclusion I was reaching. I just didn’t state it very well because I never took Physics. I coach some young people privately in math, and I am hoping to stay with them through high school because some of them will eventually get to Calculus and Physics and it’ll be nice to have an excuse — get paid — to revisit Calculus after I’ve been teaching Algebra and Geometry for 15 or 20 years. Like the Polygon Interior Angle Sum Theorem is a limit. The things I didn’t understand well in math when I was in school I try to teach the crap out of now.

How are you holding up? Do you have Young Ones at home?

Rusty Vandura - www.tinyurl.com/keepoppo > Grindintosecond
03/21/2020 at 11:55

They can do a lot of work, but relatively slowly.

jimz > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 12:11

while it did get put into some trucks, the V12 was really meant more for industrial and stationary applications like generators, pumps, mining, etc. and longevity and durability were far more important in those roles. A lower speed, low specific output engine will (all else equal) be far less stressed while making its rated power, especially for continuous duty. That’s why if you see a generator set which needs a ~400 hp engine, they’re more likely to go with a ~10-12 liter turbodiesel (or turbodiesel-based CNG engine) making rated power at 1900 rpm instead of- say- a 5.0 Ford V8 making rated power at 6800 rpm. the diesel will be (relatively) loafing along cranking out 400 hp with lower peak piston speeds and lower bearing drag than the 5.0 V8 screaming its damn fool head off.

DipodomysDeserti > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 12:17

I took basic physics in college, but never used it. Then was asked to teach physics for a few years. One of my students took and passed the AP test based on my course and independent study. Her grandfather is a world renown physicist, so that may have been more her than me.

I’m holding up alright. Our school transitioned into online learning really well. I’m just trying to rearrange my schedule so I can actually get my graduate studies in. Bad semester to take 15 credit hours. Got a seven and nine year old. Their teaches are giving them online work to do.

How you doing?

cletus44 aka Clayton Seams > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 13:07

I’m just always happy to see some GMC 702 action!

Rusty Vandura - www.tinyurl.com/keepoppo > jimz
03/21/2020 at 14:03

Yes. That makes sense. And the screaming V8 will want to snap a connecting rod at some point. That’s something I’ve pondered off and on for many, like 30, years. My friend had a Detroit 8V71 engine sitting on his shop floor. Immense and like 12 liters, but the data tag said 275 horsepower.

I made some stickers of the V12 badge last year and I am very proud of. I did the graphics from scratch in Illustrator. The numbers are all bent-wire vectors. Would you like one?

Kinja'd!!!

Rusty Vandura - www.tinyurl.com/keepoppo > DipodomysDeserti
03/21/2020 at 14:09

My year of science wound up being General Chemistry because I could take that before taking Calculus. I wish I’d taken Physics, though I do okay at pondering forces and desig ning things.

Glad to hear you’re holding up. I’ve got a 24, 21 and 18 YO, the youngest still living at home, so it’s the three of us. The eldest lives in Utah and is pregnant, due in July. We are well provisioned. I feel like we’re out at the beach, in a cottage, and there’s a Category 4 hurricane inbound. The weather’s nice, but the breeze is strong and the surf choppy.

DipodomysDeserti > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 14:33

My sister is a nurse and just sent me the presentation she received on it. The hurricane is the human response. Follow basic hygiene, assume you’re sick, and you’ll be fine (assuming you don’t already have underlying health issues, in which case you should always act this way).

I needed Calc II for my BS. I took AP Calc I in high school and received credit for it which was nice. To be honest, you learn a whole bunch about physics just by tinkering on things. Most of the kids thought the concepts were common sense, and the math nonsensical.

Hopefully everything has found its groove in healthcare by July. My wife, sister and SIL all had their kids at home, so if it comes down to it your daughter’s body knows exactly what to do.

Godspeed.

jimz > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 14:36

My friend had a Detroit 8V71 engine sitting on his shop floor. Immense and like 12 liters, but the data tag said 275 horsepower.

must have been the continuous rating. Industrial/genset engine? I know the (normally aspirated) truck 8V-71s were rated at 318 hp; old time truckers used to just tell you their engine’s horsepower and who made it. Can be a bit confusing when one of those old guys says his rig has a “318 Detroit,” he means a 318 hp 8V-71 and not a 318 c.i. 6V-53.

Rusty Vandura - www.tinyurl.com/keepoppo > DipodomysDeserti
03/21/2020 at 16:30

Thank you.

Hurricane analogy: when it makes landfall, perhaps it will have been downgraded to Category 3 or even Category 2. If that turns out to be the case, I will enjoy hearing people say “I told you so.” The nurses I know, my niece, my SIL, my neighbors, my client, are all casting about for homemade masks to wear because their employers, including Kaiser Permanente, are running short. So we’re going to make some masks.

Rusty Vandura - www.tinyurl.com/keepoppo > jimz
03/21/2020 at 16:33

No, it was out of a truck or a crane or something. I could be wrong and perhaps it was not an 8V-71. He has multiple vehicles powered by those. I’ll learn what it was. I was just startled by how small the horsepower number was compared with the bulk of the engine.

jimz > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 17:03

non-turbocharged diesels are legendarily gutless.

DipodomysDeserti > Rusty Vandura - www.tinyurl.com/keepoppo
03/21/2020 at 18:13

My sister was told not to wear a mask unless working with patients. She said they aren’t in negative pressure rooms, and is anticipating hospital staff all getting sick.