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It’s a ratio. Not a set amount. If you start with more, it will absorb more. This is why everyone says % instead of say….. F-bodies loose 20% whereas Vettes only loose 15%. Start with less, it absorbs less. %
So, if you have a fuel dragster with a 5,000hp engine you're going to lose between 500 and 750hp in the drivetrain? I can't believe that, not at all.
What are driveline losses? Why are there losses at all?
Friction.
Friction increases with the amount of force applied.
The ring and pinion is the biggest offender. It needs to change the direction of torque.
If a driveline took fixed power to turn you wouldn’t be able to turn the driveshaft by hand..
There are many other factors but the dominant one is friction between the gears and that is represented by percentage loss to estimate the frictional losses to heat.
What are driveline losses? Why are there losses at all?
Friction.
Friction increases with the amount of force applied.
The ring and pinion is the biggest offender. It needs to change the direction of torque.
If a driveline took fixed power to turn you wouldn’t be able to turn the driveshaft by hand..
There are many other factors but the dominant one is friction between the gears and that is represented by percentage loss to estimate the frictional losses to heat.
This isnt really true. Unless you mean fluid mass and viscosity loses, fruction doesnt account for the majority of driveline losses. First is INERTIA. It takes a lot of power to quickly spin up all of the weight of metal in your clutch, transmission, driveshaft, and rear diff, and especially tires. Second is fluid losses. Even with a manual transmission this is the power it takes to stir your transmission fluid, diff fluid, and such. And for an automatic transmission, there is the power it takes to run the pump and valve body, and the sometimes considerable fluid losses of the torque converter. The actual metal-on-metal friction of the parts is very small.
Energy losses do change with speed and torque. Gears rub and scrub on each other (it's an imperfect mating), teeth bend under load, parts spin on bearings, lubrication shear forces, the list goes on. I'm not educated about fluid couplers (torque converter) but I do know it behaves different than gears.
Even without knowing any of that, you can see the evidence of this by rise in oil temps and the need for larger cooling systems as more power is carried by the drivetrain. And you can hear the difference in mechanical noise (sound is a form of energy loss). If you want a real sense of how things change with conditions, then you need to see the efficiency curves for the transmission and rear axle.
Also keep in mind the car can be rigged to report higher power level on dyno. Two cars with the same power plant can report pretty big differences depending on gear ratio, tire diameter, tire rubber compound, and whether the converter is loose or not.
What are driveline losses? Why are there losses at all?
Friction.
Friction increases with the amount of force applied.
The ring and pinion is the biggest offender. It needs to change the direction of torque.
If a driveline took fixed power to turn you wouldn’t be able to turn the driveshaft by hand..
There are many other factors but the dominant one is friction between the gears and that is represented by percentage loss to estimate the frictional losses to heat.
You hit on another big one, that's as big as, or bigger, than friction, and that's "lost motion", i.e. turning the power 90°. This is 1 big reason the OEMs went to front wheel drive cars, for their superior fuel efficiency......
It’s a tech site, not an opinion site. Folks come here for answers and not opinions or “call the manufacturer” answers.
Gonna have to pay better for that dream!
Seriously though, this place allows a lot of social and off-topic discussion. That's why you have so many regulars that are here mainly for the social scene. Posting in tech threads is just part of that social scene, the topic doesn't matter, it's just another day at the club with the guys... And camaraderie is a good thing but the way this site is managed is getting you the "dark side" that you don't enjoy.
Hey, but cheer up and look on the bright side.... the average IQ here is way higher than Facebook.
John B, any plans for new LS7 or bought it as a spare while you still could get one?
Project Elco SS when I get another one but this time it'll likely be a 1970 SS since I know I would find another one as nice...here's a pic of my showroom pristine (not restored) 35K original mile Fraternal Twin "Baby" to the LS7 Monte before it was stolen last November!
Project Elco SS when I get another one but this time it'll likely be a 1970 SS since I know I would find another one as nice...here's a pic of my showroom pristine (not restored) 35K original mile Fraternal Twin "Baby" to the LS7 Monte before it was stolen last November!
MAN, that really sucks, dude!!! Sorry to hear that. I once had an '85 IROCZ 383 stroker stolen near Detroit. Got it back stripped but still had the 383 and drivetrain intact.....Been there. Always loved Elky's. My good friend once had an early 70s orange and black 454 SS El Camino. Just gorgeous.... Until his girlfriend found out he was cheating, so she took an axe to it outside a bar he was in. True story.......
We found a prestine 1970 SS 396 El Camino at the Mecum auction this weekend....checked it out yesterday and he's bidding on it this Saturday !!!
If you find it on a cable channel, watch it as he bids on the truck....... lot#30 I think.
Update on my LS427/570
Final dyno number was 491whp/455wtq, probably could have gotten over the 500whp mark, but my main goal was drivability so didn't spend too much time on maximizing power. Some more work is needed to clean up some of the dips in the curve, but I only have a couple hundred miles on the engine currently so I want to get all the changes I've made to the chassis dialed in. I didn't end up hitting my HP goal but I think that's mostly down to the headers I have. They're Borla 2010 Camaro Shorty headers. Borla claims the primaries are 1 3/4 but that's only the first half inch; they're actually 1 5/8 going into a ~2" collector. My exhaust is probably holding me back as well, it's 2.5" and built to be quiet. 1 7/8 longtubes should make a big difference, but since there are no off the shelf options that fit my RX8 I'm making a set myself, just didn't have time to finish before my scheduled dyno time.
Although I'm a little disappointed with the power numbers, it achieved most of what I wanted. In traffic it behaves the same as the stock LS3 I had before just with more grunt. No bucking or surging or other bad behavior even when it's lugging at low speed in 6th. It has a mild cam lope, but nothing obnoxious.
I need better tires, but traction is very limited in 1st-3rd. Once it gets traction it pulls hard and feels linear to redline. Happy overall, it got me most of the way to my goal, and kept the manners of a grand tourer. With a few changes it should end up at my power goal.
By the time (4 Feb 22) I read that GM had discontinued the LS7/570, all of my main, online dealers were sold out. Over the course of the next few weeks, off and on, I kept looking online for some place that might be able to find one that wasn't spoken for yet. I eventually found Pro Touring Store and, at the time, they were still advertising the original, "pre-GM cancellation price of $13,399." I spoke with the owner, Dale and he started working with his Chevrolet dealers that he normally sourced engines from. After about 3 weeks, he found a dealer that had one on order and it didn't have a buyer. He secured that engine for me. I had to wait another 3 weeks or so before it actually came in to the Chevrolet dealer and was ready to ship to me.
The engine arrived at my house yesterday. I haven't removed it from the crate but I did open up the box to make sure that there was an engine in there and not a stack of bricks !
The only picture of the engine itself. Driver's side head.
I read through this entire thread and I have to admit that I didn't know about the valve guide issues that plague these LS7s. Had I known that, I'm not 100% certain that I would've purchased the engine. Anyway, I'm happy with my purchase and the LS7's future home is in my very first, original car-my second gen, 1980 Z28.
02-15-2022, 10:53 AM
Gonna have to pay better for that dream!
