On my way to work this AM I was thinking about the maximum HP that our cars could handle. Then I had a thought:

If my car is already making the power, but it is being wasted (i.e. pushing exhaust out of the tail pipe), than you can tap that wasted power without putting any additional stress on the engine?

My list of items that can help power that is being wasted:

- Exhaust
- Cats
- Lighten up parts (pistons, rods, flywheel, wheels, tires, drive shaft,...)

If this is true, than eveyones limits on what the max HP to blow our engines is a undefine number. Since, if you add hp by say boost is much more dangerous than by tapping the wasted hp.

Let me know what you think.

 

Technically, an engine only puts down on the road about 1/3 of the energy it actually produces. 1/3 goes to the wheels/flywheel, 1/3 is expelled through the exhaust, 1/3 is expelled as heat, so i guess if you can find a way to expell heat faster, or breathe better, then essentially you can put more energy to the road.

 

i'm not sure i am understanding exactly what you are trying to say. either i am thinking way to indepth, or you are reffering to things that have already been found to be true for about a century now, lol.
there is SOOO many variables in what you have said it would take a couple pages to cover it all.
now if you can come up with a motor with no internal losses, i would keep it abit quite before a patent. professor wankel did a very fine job of that with the rotory, but it has alot more limitations than a piston engine. i have given this much thought, but nobody has obviously found a better way of doing it other than a piston style engine.

 

What he said.. Laws of heat transfer apply to engines, so it's quite impossible to create energy with no heat or exhaust. The chain is only as strong as it's weakest link, so if you keep replacing the next weakest link ie. breathing better - exhaust, intake, turbo; cooler air/overheating - radiator, intercooler, oil cooler, water injection; then you'll cram more horsepower into what was originally 287hp. Makes sense, but theory is one thing, production is another. Good Luck with that new engine invention.

 

 

lol interesting postulation. An engine probably makes 1/3rd of the power it could due to internal friction, heat, reactions happening in non-stoich.. ect. Piston engines are easiest way to convert chemical energy to electrical energy, however itll never be 100% efficient. an engine thats 60% efficient would be a marvel of science.

 

Basically what I was trying to get at as that many people state on this forum about the maximum HP that our VQ35 engines can stand. Your statement basically agrees with that is that 2/3 of the energy is wasted. If we can tap some of that wasted power than you won't put anymore stress on the engine and get more RWHP!

 

Regardless of how much "wasted energy" you tap into, the rule of thirds still apply. If you can tap into the 2/3 energy, then the overall power will increase and the heat and exhaust will increase. It still will be a 1/3 of each.

Example: Say you produced an engine with 100 hp (using easy numbers). 2/3 of that energy is being wasted (100 hp in heat, 100 hp in exhaust). If you tap into some of that wasted energy, say 1/6 of it, then you'll be producing 150hp, but 2/3 still will be wasted. (150 will be exhaust, 150 will be heat). Yes you've found a way to create more hp's, but you also need to find a way to keep the temp down and for the car to breathe better.

 

OK - Here is what I am saying:

If your engine take (for round numbers) 50 hp to push your exhaust through your tail pipe (lets say 2 - 2" pipes, 15' long) and only makes 100 rwhp, than if you install a larger tail pipe (let say 2-3" @ 10' long) than it will take less power to push your exhaust out (let say 10hp less). Than that 10hp will be applied to your rwhp and your engine will not be consuming any more fuel or air, thus it will be under the same stress making 100rwhp w/ 2" exhaust vs. 110rwhp w/3" exhaust.

I am not saying we could use more heat energy in a piston engine, I am talking about ways of making our VQ35 more effiencient to tap the hp without putting any additional stress on the internals.

 

This is pretty funny. I'm not going to start another thread on hp vs stress on the engine, as I think most people missed the point last time, or I just suck at explaining things, but I'll throw you this bone: You're almost right in your thinking. Except for all the little ways you're wrong. The amount of stress placed on the internals of our engine comes from two, and _only_ two sources, and hp ain't one of them. Stress is applied by compression force from the power stroke, and inertial forces from rpm. That means increasing the torque or increasing the rpm are the only two things that will increase the stress on the engine. Those on their game will know that doing either will generally increase hp. So in your example, the hp went up by freeing up the exhaust, but that means one of two things occured to make that happen, either the rpm increased or the torque increased. In your example the torque would increase as the engine breathes better now, which means the stress on the engine's internals went up from greater compression load caused by burning more air and fuel than before. There's no free lunch. freeing up the exhaust doesn't "release" hp, it actually allows the engine to _make_ more hp. A better example for you would be a light flywheel. The engine's power and stress are the same after this mod as before, but less energy is wasted spinning the flywheel, so more of that energy makes it to the wheel as power. Same for lightening damn near anything that rotates on the engine or drivetrain. in your example of energy being lost as heat out the exhaust, that's why people have turbos. That energy in the exhaust is being put to use to drive the compressor. Food for thought.
as far as undefined numbers to blow the engine, well yeah its undefined if you're looking at hp. I can gaurantee you I can blow your engine with the stock hp by revving the **** out of it. The resulting stress from inertial loads will be more than the rods can handle and then they grenade. The same loads can be applied by compression with too much boost, or a little too much timing to cause detonation and the same thing. All three examples will have wildly different hp numbers, but the resulting stress on the engine's internals will cause them to fail at about the same force in every case. general example: revving to 15,000rpm causes x lbs of tensile force, detonation causes x lbs of compressive force, 30psi boost causes x lbs of compressive force, and in each case, x is the breaking point of the rods. They'll all be stressed about the same when they break but with different hp numbers.
Will

 

Resolute:
I agree with your flywheel example but don't agree with your exhaust example.
You are right that hp is not the factor to be looking at for our engines- I am only using that since so many threads on this site only quote that.

For the exhaust:
For a piston to pump the exhaust through the headers/cats/exhaust pipe/mufflers it takes energy. This energy comes from the flywheel and the other cylinders that are in the power stroke at that time. If it takes the piston that is exhausting less energy to pump the exhaust out, than less energy will be taken away from the flywheel and the other cylinders that are in the power stroke. We are not increasing RPM in this example, nor have we change the intake so that more air can be drawn into the cylinder and thus the same amount of air and fuel will be used by each cylinder than with the other exhaust. That way we are getting more rwhp without increasing stress on the engine.

(this is why I did not mention intake as a way of freeing up power without causing stress on the engine)

 

I know you are not increasing rpm. You are increasing the amount of air sucked into the engine simply by increasing the velocity of the exhaust leaving the engine. That's physics. Like I said there's no free lunch. That's why opening up the exhaust ports and headers don't "free" hp, they "make" hp. You're right in your thinking there's less effort to push out the exhaust, but there's not much effort to do that anyway since the exhaust will vacate the cylinder on its own to equalize pressure with atmo once the exh valve opens. After that, the piston is mostly just pushing against atmo pressure. Relieving backpressure does more to help pull intake air into the chamber than anything else, which will increase the torque applied to the crank, and therefore hp. Relieving friction on the piston turning around the crank is an example of "freeing" hp since you are changing the resistance to the force applied to it. Opening up the exhaust doesn't change resistance to the piston as much as it increases intake charge, and thereby hp.
Will

 

"That's why opening up the exhaust ports and headers don't "free" hp, they "make" Will[/QUOTE]

The engine develops Tq the opening up of exhaust facilitates that..

 

As Skee-Lo said,
"I wish i was little bit taller,
I wish i was a baller,
I wish i had a girl who looked good
I would call her
I wish i had a rabbit in a hat with a bat
And a six four impala"

What does this have to do with this conversation......about as much as all this talk has to do with the VQ motor. Do some research before you post things like this.

 

It must be good to be the King? So you can sit on your throne, have nothing useful to say, and just put people down that are trying to have a discussion, no one asked you to read this!

 

Search and read the millions of threads on cams and how they help the efficiency of the motor(same boost=more horsepower) and many of your questions/postulations will be explained. Follow that up with any of the conversations on 3"/bigger exhausts. Then look up at the sticky up top on building a motor and you will find out the weak links in our motors. Then go to google and look at exhaust scavenging and thermal efficiency of an internal combustion engine. I didn't mean to offend you, just having a little fun. You asked a question more geared towards a mechanical engineering professor and not a forum about FI VQ's. That was my point. Again, sorry If you were offended.

 

No offense taken.

I wasn't trying to have a discussion on exhaust. I was trying to make a list of items that you could change on a piston engine to get more HP without causing any additional stress.

I read many threads about people opinions for the max hp a VQ35 engine can stand. Since this is the standard laymens term for what the max stress you can put on the engine, I want to basically prove them wrong. Trying to brainstorm ideas with your help on what I can do to Increase hp with little or no increase in stress.

I guess the list now is for no stress:
Light weight flywheel
Light weight wheels
Lighten Internals

What would be a list for a increase in HP for a little added stress?
- Exhaust
- Intake
- Cams

I know for sure that adding more boost will get me to the hp I want, yet looking for alternatives to keep from blowing my engine.

 

It's a good question. I just get a little wary of trying to explain on a forum what a physics class would cover. MoodDude, again, your thinking is right in that relieving resistance on the piston would produce more hp, but that's not how opening up the exhaust works. That's how lightening the reciprocating assembly works, or coating the piston skirts with a friction reducer works, but opening the exhaust does not change the energy released out the exhaust. As I said earlier, it does allow more intake charge by relieving the resistance against the incoming air, and this allows more air/fuel for combustion, which increases torque, and an increase in torque results in an increase of stress on the engine. Have I already mentioned there's no free lunch?
Will

 

heres the issue. sure if you wanted to get all titanium internals, you will save some of the rotational weight. look at the cost associated with this. to pick up a few hp?!?! now if you are turning the motor to 10-15000 rpm, you would need those parts as heavier ones would rip apart. why would you run a motor to that rpm? to gain more power and take advantage of huge cam and port sizes. as will has said (no free rides).
now if you can design a motor with no losses, you would be genius!!

 

This question has been posted before and I still believe it is the wrong question to ask. Given the car in question is put together and tuned properly, I think the question should be...

What is the maximum torque the VQ can handle?

It seems people who blow motors are all over the board HP wise, but I rarely see anyone post what torque they are hitting when they blow. I bet there is more consistency on that end than the HP.