A&Q about 350Z
Q:
Show me a freaking 400hp diesel that can push a 3000lbs car on 285 series tires with 56mpg I dare you. Or better yet show me ANY 3000lbs High proformance car that gets 56 mpg on any fuel. Dude you are starting to reak of $hit, I would recomend that you do some reserch before start bashing someone else.
A:
Lets get this thread back on track without any more Interruptions from people that don't even know what I am talking about.
A:
You need to do a little more research.
Power does not drop off over 17:1 compression. The reason turbo engines run a lower [b]static[/b>\] compression ratio is because the boost gives you a dynamic compression ratio that is much higher.
Without a high compression ratio, you're going to be exhausting very hot air. This ensures you will never get good efficiency.
I don't know how old you are, but belt and cone CVT's have been around for around a century. To claim you "invented it' as a 12 year old before engineers did is truely silly. Indeed impossible given you are most certainly not the worlds oldest living person.
Claiming that professional engineers are blinded by "how things should be" is again rather silly. I suggest you spend a few days working with a some engineers, you may learn a lot. But only if you are capable of learning.
A:
We were discussing fuel economy, not power output.
Yes there are many diesels which could push a corvette along the highway and get 56mpg. But they won't have 400hp.
The title of this thread is "larger engines for better mpgs?"
Not "mixing performance and economy".
A:
I am not claming that professional engineers never invent anthing usefull, but they are given R&D projects that are just slight improvments over curent ideas, and I am sure that the CVT was not invented a centure ago, otherwise they would be perfected by now, I remember a few years ago reading in a magazine that Audi was just starting working on the variable pully design, I have spent many hours talking with engineers. My girlfriends dad is an engineer for Chrysler, he engineers gears for their transmissions, and he still knows nothing of CVTs. They are usualy very narrow minded in their feilds, mind you I am not being arrogant, he knows more about the working of gears than I will ever know, but that is his specality. BTW if you read GMs assesment of compression ratios and their effect on torque you will see that at aprox 17:1 CR you stop gaining torque, it is called diminishing returns if you study engineering you will see what I am talking about. I know a little more about the internal combustion engine than what I am letting on so don't try to debate me without some serous ammo OK, anyway lets get back to the subject at hand.
A:
Yes but if you actualy READ my posts I am talking about cutting edge proformance and fuel effecency, besides the most fuel effecent diesel car I have ever seen gets 49 MPG and only has about 98hp, far from 56MPG.
Look dude I am not trying to be rude but everything you have said thus far has been third grade crap.
Diesels get better fuel economy.... well no $%^@ higher BTU fuels have that tendency
High compression ratios provide more torque..... you don't say
A:
I am a professional engineer.
Diminishing returns are completely different to your claim of "losing power".
Yet the diminishing returns is exactly what is happening with the petrol engine.
You are assuming that because CVT was not in production in an automobile that it was not invented.
That is a very poor assumption.
Belt/pulley and cone CVT's have been used for speed control in machinery for a century.
They haven't been used in automotive because until recently they haven't been made small enough, light enough, cheap enough and at the same time maintenance free for the 300,000km or so an automobile has to last for.
Buy yourself a thermodynamics book and start reading.
The Carnot cycle will tell you straight away that what you propose is not going to work.
The Otto cycle will give you a few more ideas why it's not going to work.
When you're done with those, get out a fluids book and figure out what the pumping losses are with a throttled petrol engine. This will show you what an appalling waste of space a throttled idling petrol engine is and why large petrol engines use a massive proportion of their output literally strangling themselves.
Then start drawing.
Do the layout of your six inch stroke engine and tell us how tall it is going to be.
I have a 120mm stroke pushrod diesel which is approximately 800mm tall from sump to rocker cover. That seriously restricts what vehicles can use the engine.
A 150mm stroke engine is suitable for only large commercial trucks. Large commercial trucks are not interested in petrol and never will be.
A:
VW have diesel cars which use only 2.6 litres of diesel per 100km on a straight level run
I see you edited your post to include the BTU's of diesel.
Diesel fuel has roughly 10% more energy than petrol by volume. Weight for weight they're about equal.
A:
Oh goody you are a pro, so mr pro since you are doing such a great job (LOL) at bashing my ideas why don't you tell me how much heat a cylinder looses during a power stroke, or how much energy is lost in the swept area or anything usefull...come on anything if you are a pro why don't you know anything about compression ratios?? why have you not contributed one usefull fact to this thread thus far??? I have to say I do not beleve you, what do you engineer chew toys???
A:
Guys... you are both starting to pi$$ me off. Stop flaming and get back to being objective or I'll close the thread.
There are no set rules. You can't calculate everything like heat losses unless you know the efficiency of the coolant, the specific heat gravity of the alloy in the cylinder walls, how much of the time the flame spends touching the walls integrated with the rod/stroke ratio and what part of the cylinder is uncovered at any given time, not to mention adiabatic changes in the volume of the cylinder. Factor in VE, induction type, cam timing, and all the other things and there is no real way to quantify everything.
That's why the same basic small block chevy can get as little as 1 mpg or 100 mpg depending on how its set up.
The bottom line here (if I read the posts correctly) is that we're talking about converting the stored energy in the fuel into motion in the most efficient means possible, right? So let's talk about it rationally, not by throwing bricks.
A:
The energy lost to heat depends on too many factors to simply throw out a value. You need to lock down the exact situation before you can calculate anything meaningful. So when you know the materials, temperatures, geometry of everything, gas velocities, specific heats and the rate of expansion then you might be able to start.
But I can tell you that it's a whole lot less than the energy that gets thrown out as hot exhaust.
I have told you about compression ratios. But you chose not to believe it because it doesn't fit with your own theories.
Read this
A:
Well said, I was waiting for you to show up Curtis, you usualy have an anwser to just about everything, I have a rough idea how much torque it takes to overcome the friction in a cam, but I have no idea how much it takes to overcome the friction in the swept area of an engine, do you have any clue?
A:
OK lets take out the variables, assuming the same aloy, same combustion dynamics, same compression ratio, how much more energy will we loose with twice the surface to volume ratio? Or a better way of saying it how much more energy will we retain with half the surface to volume ratio? I don't need an exact number, I know that would be nearly imposable, the process by which the block was cast or forged could effect the conductivity of heat I am just trying to get a rough figure, in the avrage internal combustion engine we loose 63% of the energy as heat though our exaust and coolent systems, I am just trying to figure how much of that can be saved if it has fewer ways of getting out. BTW your link does not work.
A:
Going to bed, I have work in a few hours. I'll continue debating tomarow TTYL
A:
It works fine. It's a powerpoint presentation.
If you don't have powerpoint, download openoffice.