What is Horsepower?

[Al Smith]

It will be interesting to see what comes of auto race engines once solenoid operated valves become the norm in a few years. I wonder if the old camshaft will still be king on race day.

Frank,you're either been reading popular mechanics or you are a corperate spy.I just recently heard of this idea myself and I'm supposed to be in the "loop".
Oh,by the way,it's already happened in prototypes..Hang on Sloopy,the internal combustion engine is not done yet.

 

[chowdozer]

Novaman I think you are referring to rod failure from tension at high revs on a forced downshift etc. if you are talking about piston outrunning flame speed. The piston wont outrun the flame very much if the flame is driving it. I was referring more to not having piston speed too low. Piston speed, stroke, rpm and compression ratio are rather tied together in determining where an engine will develop its maximum horsepower. If burning gasoline is the fuel, these things have to be matched to its expansion rate, within reason, to have any kind of efficiency. How you put it together determines the character of the engine. As was mentioned relative rod length and such things as bore offset can have some interesting effects on changing piston speed and accelleration during different phase of crank rotation. Where weight and space is a concern a given horsepower is easier achieve with less torque and more rpm. It will be interesting to see what comes of auto race engines once solenoid operated valves become the norm in a few years. I wonder if the old camshaft will still be king on race day.

I'm not sure we'll see solenoid operated valves on the average car for the next 20 years. The only benefits they have is less reciprocating weight and less friction. Several manufacturer's are already offering engines that change intake and exhaust valve timing. I can't think of a reason to change a single valve's timing versus the whole bank unless it's a system like the Cad Northstar that drops cylinders with the FI so the engine can run without coolant. A couple other considerations that would need to be looked at would be machining and parts costs and the MTBF for a solenoid versus a cam at say 25 Hz (3000 rpm). I think they may show up on some performance vehicles but I don't know what the frequency limit on a solenoid is. I'd have to say a cam can go higher. The other day, someone posted a link to a F1 engine that turned 20K. That's 167 Hz on a 4 stroke and seems kinda high for a solenoid. JMO of course.

edit: if we do see solenoid valves, I'd expect to see them on a hybrid where the manufacturer is trying to extract every available hp at a reasonable rpm and people are willing to spend extra $ to have a green feeling.

 

[ShoerFast]

Enjoying this read! opcorn: you both are making good points!

What a change from the head-bonkers ball.

 

[Simonizer]

That is exactly why I started this thread. There have been some excellent posts. Cheers, Simon.

 

[Crofter]

Chowdozer, I dont know about the cycle frequency limitations of solenoids but I know they are going to system voltage of 48 instead of 12. One of the benefits of solenoid operation is the valve opening can be much faster than with any reasonable cam profile. Alleviates a lot of needed lead time opening and closing (valve overlap). As you mentioned individual cylinder monitoring can tailor fuel and valve timing and cylinders can be idled at will. It is quite common for some cylinders to need different timing or fuel adjustment to account for temperature differences and intake runner placement; with computer control also of individual valves they can each be at optimum conditions. A camshaft valve train is quite a high percentage of overall friction loss and is noisy, expensive, takes up space, and constrains valve placement and numbers. It may prove to be a fiasco in the implementation but the future thinkers seem to feel it has merit.

 

[Al Smith]

You may find this hard to believe but the individual ignition firing rate per cylinder is used on modern engines.The technoligy utilized now is for variable valve timing using dual overhead cams,4 valves per cylinder.The intake cams can be advanced or retarded by the use of lube oil type hydraulics as per the engine control modual.

I would not be surprised if camless engines are on the market within ten years or less.You could in theory have a 4-6-8 engines that would work much better than the Cadillac failure of the 80's.

 

[NovaMan]

Novaman I think you are referring to rod failure from tension at high revs on a forced downshift etc. if you are talking about piston outrunning flame speed. The piston wont outrun the flame very much if the flame is driving it. I was referring more to not having piston speed too low. Piston speed, stroke, rpm and compression ratio are rather tied together in determining where an engine will develop its maximum horsepower. If burning gasoline is the fuel, these things have to be matched to its expansion rate, within reason, to have any kind of efficiency. How you put it together determines the character of the engine. As was mentioned relative rod length and such things as bore offset can have some interesting effects on changing piston speed and accelleration during different phase of crank rotation. Where weight and space is a concern a given horsepower is easier achieve with less torque and more rpm. It will be interesting to see what comes of auto race engines once solenoid operated valves become the norm in a few years. I wonder if the old camshaft will still be king on race day.

Not so much a forced downshift, but maybe a missed shift (I'm a drag racer). If rods were infinitely strong, flame front speed would limit no-load WOT RPM in most 4-cycle engines. But the rods are typically a bit of a weak link, especially if they aren't aftermarket forged pieces with good rod bolts.
I had never really thought about matching piston speed to flame front speed before I read your post, but it makes sense. With American V8s, us drag racers just adjust the ignition timing so that peak cylinder pressure is timed optimally with whatever fuel the engine is set up to burn.

Edit: didn't Ducati use hydraulically-actuated desmodromic valves in some motorcycle engine?

 

[Al Smith]

With American V8s, us drag racers just adjust the ignition timing so that peak cylinder pressure is timed optimally with whatever fuel the engine is set up to burn.

I've heard it said on monster dragster engines,3,000 odd HP that if the ignition hiccupped just once in the first hundred feet that the engine would fly apart like a dollar watch.That nitro is blown into the cylinders at nearly liquid consistency.The plugs are gone after the first hundred feet and the dang thing in essence diesels the rest of the way using the glowing valves as an ignition source.The engine life is measured in seconds not too many at that.

 

[Fish]

So Simon is the "Godfather" of chainsaws, he is pulling all the strings...........

Or at the least, gently massaging the strings

 

[Fish]

Or the hamstrings of his college wrestling buddies

 

[Mr.]

There is so much nitro being pumped into a Dragster engine that the fuel/air is a SOLID mass. And you can over double that HP rating Al.

Lot's of ponies. YEAH HA!

Fred

 

[Mr.]

Or the hamstrings of his college wrestling buddies

I thought it was g-string.............

Fred

 

[ShoerFast]

As nitro oxedizes, it burns very evenly, a high pressure but smooth comparatively to the power it makes.

This rod , 12" journal and works well with a 12" stroke, wights about 100# . back to were the TQ comes into the equation, this rod likes PRM's at or below 330RPM's. It is not hard to pull 100HP with this rod, comes in a 5 cylinder (500HP)

Pictured with an MS-180 on loan from the Ultra collection.

 

[spacemule]

What kind of machine is that out of, shoer?

 

[ShoerFast]

What kind of machine is that out of, shoer?

We could bet that it is a stationary engine!

Thats from a Galluan Hymonigiser <sp

 

[chowdozer]

Chowdozer, I dont know about the cycle frequency limitations of solenoids but I know they are going to system voltage of 48 instead of 12. One of the benefits of solenoid operation is the valve opening can be much faster than with any reasonable cam profile. Alleviates a lot of needed lead time opening and closing (valve overlap). As you mentioned individual cylinder monitoring can tailor fuel and valve timing and cylinders can be idled at will. It is quite common for some cylinders to need different timing or fuel adjustment to account for temperature differences and intake runner placement; with computer control also of individual valves they can each be at optimum conditions. A camshaft valve train is quite a high percentage of overall friction loss and is noisy, expensive, takes up space, and constrains valve placement and numbers. It may prove to be a fiasco in the implementation but the future thinkers seem to feel it has merit.

Frank, one of the things I think about on the solenoid/valve idea is the MTBF of the solenoid. I don't know what type of solenoid manufacturers would use and I also don't know the MTBF of different valve types. If we make a couple of assumptions, say 300K mile life at an average speed of 25mph and a 2000 rpm average, that would translate to 720 million cycles for the solenoid. I would think that the solenoid would have to be replaced many times during that period but I'm only guessing.

A year or two ago, there were some articles in Home Shop Machinist on building a solenoid actuated valve train for a two cyclinder engine. It was an interesting series of articles as the author had designed and built the engine, valve train and the electronics.

I can see the benefits solenoid valve actuation, I'm just not sure of it's feasability or durability. I suppose where there's a will there's a way.

You may find this hard to believe but the individual ignition firing rate per cylinder is used on modern engines.The technoligy utilized now is for variable valve timing using dual overhead cams,4 valves per cylinder.The intake cams can be advanced or retarded by the use of lube oil type hydraulics as per the engine control modual.

I would not be surprised if camless engines are on the market within ten years or less.You could in theory have a 4-6-8 engines that would work much better than the Cadillac failure of the 80's.

Al, my current Toyota uses a twin cam 4 valve/cylinder with variable valve timing and ignition as you describe. I don't know how much power it adds, but it does add alot of complexity. I will say that the Toyota doesn't get that great of mileage.

I'm a little old skool you know? Give me a good healthy 350 V8 and I'm happy!

 

[Al Smith]

They have new auto engines so technified the average mechanic can't even work on them.The good part is they usually go a long ways before a wrench needs turned.

When I was a teenager in the 60's about 50 thousand miles was what a car would run before in the least,a valve job.Now the cheapest thing on the market is good for 100 thousand plus.

 

[Drive_1305]

I was gone for a few days and I come back and read over the post and I just can't understand where this "Torque doesn't matter" theory comes from....... It takes Torque to cut wood...... To cut wood, it takes a force to pull the chain through the wood. This force comes from the sprocket. As it turns, the teeth exert a force on the chain and pulls it through the wood. This force is a distance r from the center of the shaft- where r is the radius of the sprocket. This force and distance r = TORQUE. The engine has to produce Torque to overcome the resistance of the wood-no matter what the cutting speed is. To cut fast, you need sufficient torque to overcome the load and high rpm. The "No Torque Theory" just doesn't cut it!

Then they say its all about raw HP- I assume raw means a high value. That makes more sense, but look at the equation... HP= T x rpm x c , T is torque, c is a constant( who cares what it is). So when the saw is cutting wood the only reason it produces a high value of HP is because it produces enough torque to overcome the load and it does it at a high rpm. Their "Raw HP" theory talks like torque doesn't have anything to do with it, but it does.

The only thing I can think of is they're writing down equations and Torque cancels out so then then they conclude "Torque doesn't matter". Something has to pull the chain through the wood- that something is Torque!

Maybe they've looked at graphs of Torque and HP from a dyno test. Maybe as rpms increase the Torque dropped but the HP increased, which I suppose can happen, I'm not that familar with these graphs. So maybe they say, Torque decreased so it quit doing the job and the high HP took over. Or maybe they're trying to say the high rpm part of it is more important than Torque- I don't know, but still to cut wood you have to have a sufficient amount of Torque to over come the Load. Bottom line... it takes TORQUE to cut wood!

 

[NovaMan]

Uh, I was thinking mostly of gasoline engines, but nitro is definitely awesome.

I'm a little old skool you know? Give me a good healthy 350 V8 and I'm happy!

Apparently I rep'd you too recently to get you again.

They have new auto engines so technified the average mechanic can't even work on them.The good part is they usually go a long ways before a wrench needs turned.

Rep'd ya.

 

[drmiller100]

i thought of an analogy.

so imagine a cutting tooth of a chain chipping out a little piece of wood.

if you don't have enough torque, because the tooth is too dull, the chain stops moving.
if you don't have enough torque because the drive wheel is too big, teh chain stops moving.

but ulimately, if you put a little teeny wheel on, you are guarnateed plenty of torque, and you are guarnateed to chip a teeny bit of wood out.

The goal however is to CUT THE LOG QUIKLY.

to cut the log QUICKLY, the question then becomes how many chips can you cut in a given time period.

This is determined by sharpness of chain, hardness of log, and HORSEPOWER.