No Free Lunch, hp cid torque gearing

[273]

I want to show how these are interrelated, this ain't meant to be best way and is obviously theoretical, in the real world there's so many variables so here most everything is assumed to be same VE% and efficiency.

First off need to define hp, most here seem to think torque and hp do two different things torque is basically the output of one revolution and hp is all the revolutions added up. Hp is the combined ability of torque and rpm, why is rpm equal to torque cause if one engine is doing 500 lbs-ft per Rev and second is doing 250 lbs-ft per rev but doing twice the revs. Both are doing the same work it just takes the second two revs in the
same instance of time as the first engine. Torque over time does everything aka drive accelerate tow etc.. and we call that hp.

Most engines we use for our cars efficiency is very similar so the fuel and air required per hp is fairly narrow in range. So no matter the static displacement aka 340 426 440 etc.. The engines have to displace a similar amount of air "cfm" dynamically (running) for same hp. So in other words for a given hp all engines have to displace the same amount of air no matter there static displacement. So say 400hp is about 550 cfm No matter what static displace it will have turn a certain rpm to displace 550 cfm (rpm x Cid /3456 =cfm) ve% efficiency etc. will effect rpm eg. 318 @ 6000 rpm or a 440 @ 4300 rpm.

Torque is basically a single power stroke so the more the displacement more
torque per stroke. Most seem to think longer stroke in same displace will produce more torque, true it will have a greater multiplying effect but it will have a smaller piston which has less surface area therefore less downward force to be multiplied. Also Torque per Cid is also happens in a very narrow range 1:1 - 1.45:1 lbs-ft per Cid if average guy can do 1.15-1.25:1 your doing pretty good.

So, so far it takes a certain amount fuel and air within a narrow range and a engine will have to dynamically "rpm" displace the air which will make lbs-ft:cid per rev in a somewhat narrow range and ve% and Cr having a lot to do with that.

Next is gearing, if geared for max performance or proportional compromised, torque to the ground should be similar between engine of different sizes with similar hp it's torque per Cid ratio matters not overall torque numbers especially when comparing vastly different displacement.

Obviously In the real world there's so many varying factors, but there's no free lunch if an engine makes more hp has to be from being more efficient and or more fuel and air. For any given hp if done right displacement torque gearing should cancel each other out for the most part at least that's how I see it.

 

[rumblefish360]

(Roll eyes)

 

[furrystump]

So, going backwards. One lb of fuel can produce X amount of energy. It takes a given amount of oxygen to burn that fuel. In an internal combustion engine, we use pressure to create motion. We know the practical highest compression ratio. We also know how much pressure one lb of fuel will produce.l when burned starting at the pressure within the cylinder at TDC at the max practical compression ratio. Nothing in the above is variable, you could argue highest practical compression ratio, but not greatly. The rub! In a NA engine the amount of oxygen you can get into the cylinder is limited to a little over 100% VE. So the amount of oxygen is limited. Which limits EVERTHING else. We really argue about what mechanical way we convert that pressure. Small bore/big stroke or big bore/small stroke or big bore/big stroke or small bore/small stroke.

 

[furrystump]

But don’t feel bad! Engineers don’t even agree, you see big ships with huge slow rpm displacement, big bore/big stroke engines and ones with relatively small high speed turbines. Small bore/small stroke??

 

[Rat Bastid]

So, going backwards. One lb of fuel can produce X amount of energy. It takes a given amount of oxygen to burn that fuel. In an internal combustion engine, we use pressure to create motion. We know the practical highest compression ratio. We also know how much pressure one lb of fuel will produce.l when burned starting at the pressure within the cylinder at TDC at the max practical compression ratio. Nothing in the above is variable, you could argue highest practical compression ratio, but not greatly. The rub! In a NA engine the amount of oxygen you can get into the cylinder is limited to a little over 100% VE. So the amount of oxygen is limited. Which limits EVERTHING else. We really argue about what mechanical way we convert that pressure. Small bore/big stroke or big bore/small stroke or big bore/big stroke or small bore/small stroke.

There is zero power in oxygen. Power is in the fuel. And it’s not only how much fuel you can burn, it how well you burn it and how many times per second you can burn it.

That’s the simple answer to it. You can look at a dyno sheet and see how much fuel an engine is burning and know if it’s competitive or not.

 

[Phreakish]

But don’t feel bad! Engineers don’t even agree, you see big ships with huge slow rpm displacement, big bore/big stroke engines and ones with relatively small high speed turbines. Small bore/small stroke??

That's not disagreement, that's design for application.
People tend to forget that no engine is designed for any ONE thing - packaging and manufacturing still dictate a bunch of it. Hell, even in racing the OEMs basically set the standard even if only tangentially, and then competitors have to work around the constraints.

 

[Phreakish]

There is zero power in oxygen. Power is in the fuel. And it’s not only how much fuel you can burn, it how well you burn it and how many times per second you can burn it.

That’s the simple answer to it. You can look at a dyno sheet and see how much fuel an engine is burning and know if it’s competitive or not.

Yup!

How much fuel an engine can burn is dictated by displacement.
The RPM capability is dictated by the airflow.
The combustion efficiency is dictated by compression.
Output efficiency is dictated by friction.

"Airflow" covers a lot of ground, because it has to take into account pressure drops, recovery, and temperature gain/loss as well. Friction matters more than most people realize - and not just in the rings, though those have probably one of the biggest impacts, or is the one which we have the most control over.

The typical hot rodder gets all these wrong. They run too much displacement for the job, then put a tiny head on it that keeps the rpm potential under 6k to avoid spending money on good springs (but muh torque!), then they run low compress "for pump gas" and then use ancient ring designs and cylinder prep that makes as much sense as driving with the parking brake on. Then they seem puzzled by 8mpg and the fact that a Camry can outrun them on the onramp. Shameful.

The way a motor is fueled also matters. TBI/Carb are entirely different rules, than port or direct injection and not just because of 'wet flow' - it's all a matter of vapor pressure which requires a balanced approach to induction.

 

[Scody21]

There is zero power in oxygen. Power is in the fuel. And it’s not only how much fuel you can burn, it how well you burn it and how many times per second you can burn it.

That’s the simple answer to it. You can look at a dyno sheet and see how much fuel an engine is burning and know if it’s competitive or not.

There is some disagreements in circles about jet engines looking at the weight of fuel consumption per hour vs weight of fuel the plane can carry. And that the fuel usage is way lower thus the A/F ratio is vastly different than an ICE engine.

The other one is, why are Oxygen enriched fuels like Q16 being used in N/A racing engine if O2 has no power. Don’t flame a fire…. LoL seems that more O2 makes for a better fuel burn reaction…

 

[T56MaxTorq]

Plus, all engines have different efficiencies at different rpm.

 

[Rat Bastid]

There is some disagreements in circles about jet engines looking at the weight of fuel consumption per hour vs weight of fuel the plane can carry. And that the fuel usage is way lower thus the A/F ratio is vastly different than an ICE engine.

The other one is, why are Oxygen enriched fuels like Q16 being used in N/A racing engine if O2 has no power. Don’t flame a fire…. LoL seems that more O2 makes for a better fuel burn reaction…

And you run a bigger jet with oxygenated fuel. If you don’t they lose power. Fast. You have to burn fuel to make power. Simple as that.

 

[Phreakish]

There is some disagreements in circles about jet engines looking at the weight of fuel consumption per hour vs weight of fuel the plane can carry. And that the fuel usage is way lower thus the A/F ratio is vastly different than an ICE engine.

The other one is, why are Oxygen enriched fuels like Q16 being used in N/A racing engine if O2 has no power. Don’t flame a fire…. LoL seems that more O2 makes for a better fuel burn reaction…

How many jets burn gasoline? Of course the AF is different. Not only that, but combustion happens in cycles, jet aircraft steadily consume fuel to produce heat, and most of the work done is to expand air across a power recovery turbine in order to generate more work. It's also easier to sustain the process in a jet engine across a wider operating regime (higher altitudes) than a piston engine.

The oxygen in oxygenated fuels doesn't add power, it crutches engines that can't ingest more from the atmosphere. There's a practical limit though, since some amount of non-reactive atmosphere gets heated and expanded by the heat released from combustion. I haven't looked deeply, but I bet there's certain gasses which would expand more and gain heat faster than nitrogen (which makes up the bulk of our air) and would increase the efficiency of an ICE engine by reducing the amount of waste heat in the exhaust stream.

Heck, even older aircraft captured some of the waste heat from radiators to boost propulsion. Same from the exhaust stacks...

At the end of the day, it's still a matter of how much chemical energy you start with, and how much you turn into work.

 

[AJ/FormS]

When designing an SBM street engine, to actually be a DailyDriver, one very quickly hits a wall in getting air into the engine at higher rpm. Sure you could install a bigger cam and so on, and the project quickly spirals out of the realm of DailyDriver. Been there done that.
Whereas getting a liquid fuel into her is easy peasy.
Fresh cold-air induction and Oxyginated fuel
are just two ways of getting around the restriction. Which is why my engine has only once ever not burned 87E10. It may not be much, but it lets me use a slightly smaller cam, which has a slightly earlier closing intake valve angle, which then makes a lil more cylinder pressure, which makes her a lil more energy efficient, and saves me money at the pump every time I fill it up. That's a triple win for me.
E10 is the ONLY oxygenated fuel we have locally besides E85. If we had E20, I would happily tune for that.

I went on the hunt to find out how much oxygen is actually in E10, but results are or seem to be shrouded. It depends a lot on where you are and in what season. The smallest Oxygen content I found was 2% and the most was 7.6%
A gallonUS of straight gas is said to weigh 6.3 pounds. To make E10, you would take out .63 pounds of gas and replace it with .63 pounds of ethanol. If that ethanol contains 7% oxygen, that would be .044 pound of oxygen. How many oxygen atoms would that be after disassociation from the fuel, compared to how many atoms of oxygen are in a cubic foot of dry air that contains about 19% oxygen be weight.
IDK the answer to that