Your port size arguement goes out the window becasue of different valve angles. Apples, oranges comparison.

How exactly do you measure the velocity in a running engine...........

 

i measure port velocity according to :

first cross sectional area.

second port runner volume.

third valve angle.

 

I don't understand. Is a valve angel something like Maxwell's demon?

 

woops, i meant angle not angel, so it is valve angle.

 

I have read a brief section of this thread and feel there is alot of misinformation..

here is a "basics to engine design" which may clear up some confusion

Power is the result of extracting the chemical energy from the fuel. More Power is a results of More fuel being burned and using that heat energy more efficiently. (also, torque doesnt mean much.. power is important)

Because we are talking about Naturally aspirated Spark Ignition Gasoline engines, the air-fuel ratio lies within a narrow range. For simplicity sake, we'll assume a constant Air-fuel ratio.. This means that we need to add air at a porportional rate to fuel..

Whats the limitation? Well we all know you can get bigger injectors and bigger fuel pumps.. so we arent limited in fuel supply. However, a natually aspirated engine is limited into how much airflow it can ingest. This means that our focus to maximize power would be to maximize airflow!

To accomplish this, there are only 2 basic options. RPM or displacement(note i did not say increase stroke or bore specifically). At the end of the day, MASS AIRFLOW is the name of the game.

I'll discuss RPM first.. because of the fixed displacement of the engine it can only ingest so much air per revolution. Therefore, to make more power, you would want to spin the engine faster. You quickly run into limitations once you start pushing the RPM higher in your car, such as; valvetrian staibility, rotating assembly strength/balance, cylinder head flow, valve size.. etc

Due to the limitations that show up with RPM, you can also increase displacement to increase airflow per revolution, (i.e. torque). This can be accomplished by increasing bore or stroke... or both. One or the other, in its own right, does not increase torque more than the other. Displacement is what makes torque!

Having large stroke and small bore will run into rpm limitations with the rotating assembly and valve size (smaller bore only allows for small valves) Airflow restriction typically increases dramatically on these configurations as rpm goes up.. thus they are known as "low rpm torque monsters" because they die at high rpm because of the valvetrain/cylinderhead airflow restrictions

Having a large bore and short stroke can run into mixture motion issues, valvetrain stability issues, etc.. But you can have very large valves in relation to displacement. If you have a given displacement, going this route will assist in higher rpm operation (i.e. forumula 1).

at the end of the day, there are tradeoffs for all designs.. far to many to list here.

 

Nice concept but when executed it does not work. A heavy flywheel is the old school way of shocking the tires harder. once engaged, you will make more torque/hp because of the reduced rotating mass, but you should gain both.

Nice try for the 2nd post though. Just please try to refrain from being cocky on here.

 

MY dad and I have a 1955, 210 with a 4 speed and a 283. We have experimented with aluminum and steel flywheels and how they affect the way the car drives. The only place they made the biggest difference is when you street or track drive the car. Like said above the heavier steel flywheel would give the engine some extra inertia when launching to prevent bogging, however the engine would take longer to rev due to the larger rotating mass i.e 35 lb flywheel as opposed to the 14lb. The aluminum flywheel let the engine rev faster and the clutch would bite the surface harder but the engine sometimes would bog or die from lack of rotating mass unless you launched it at a much higher rpm.

This I think is a good example of how your idea doesn't effect the torque produced at the flywheel but it does increase the torque number at the tires. The torque output of the engine is largely effected my the stroke of the crankshaft not the flywheel bolted to it.

 

Try not to bash unless your giving him the correct answer. Remember, we are all here to help one another in our quest to keep our LS1's the coolest cars on the road

 

the 4" stroke is going to spin easier, but the 4.1" is going to make more power for the simple reason its bigger. figure ve doesnt change much, the extra volume is going to go a long ways.

 

You don't know how the combustion engine starts and runs. I suggest you check out www.amazon.com and do a little reading. you dont read cause you cant read and you cant read cause you dont read. I might be new here but please dont post on any forums anywhere involving cars.