Yeah, I know how you can solve all the problems of high compression with pump gas.. don't use pump gas!!!

 

Where do you think the power from nitrous comes from? It's oxygen, just put in the engine in liquid form and then cracked. It's exactly the same as forced induction, except for the small head start in cylinder temp. 100 HP worth of pressure from nitrous EXACTLY EQUALS 100 HP worth of pressure from forced induction, it's very simple physics. Combustion pressure turned into linear motion, translated to rotational motion, etc. Pressure is pressure, and pressure equals heat. Too much heat and ping!

The small head start in cylinder temp from nitrous really isn't that much, because you're only cooling the air that is drawn in. Nitrous doesn't crack until well over a thousand degrees, so it's not like you're igniting some cold liquid.

 

The purpose of nitrous isn't just to cool the intake charge. While that is a bi-product of the gas, the purpose is to fill the cylinder with more air. Nitrous brakes down at roughly 570 degrees (not 1000+). With the added oxygen in the cylinder, you must add more fuel to keep A/F's safe.

Wether its a turbo, or supercharger, nitrous, or all motor (better flowing heads)...the goal is to burn more fuel. Each power adder has its own way of doing so. Burn more fuel=make more power


Horsepower is increased when you can burn more fuel. Just like runnin methanol in an engine. Instead of the 13.5 A/F commonly used with pump gas (or race gas for that matter) methanol is about half that, which means you can use twice as much fuel. (example: RLZ's all motor car used (4) 440cc injectors on gas, they switched to meth and they needed (4) 1600cc injectors at almost 90% duty cycle!!!)

 

You've got that very backwards.
The specific energy of methanol is less (roughly half of) than that of regular gas, but the energy of the stoiciometric mixture is almost identical. This means that you actually have to burn twice as much methanol to make the same amount of power, your power doesn't go up with the amount of fuel added. If you converted a regular engine to run on methanol, you'd burn twice as much for the same power output. And again, it's all about cylinder pressure. The pressure doesn't come from adding more fuel, unless you add enough o2 to go along with it. Too rich of a mixture will make you lose power, etc.

Methanol has the same advantages as race gas: very high octane, usually over 120 for pure methanol. The latent heat of vaporization is 3 times greater than gas, so that really helps to cool the intake charge and keep cylinder temps low.
So you can run crazy compression or high boost if you want. The power doesn't come from the methanol itself, it comes from what methanol allows you to do.

I thought the 575 degree breakdown temp was C, not F.. whoops.. That's what I get from not looking it up.

 

I apologize, I didn't explain myself well. You are correct about the specific energy being half that of gas. But there are gains from using meth. without any other mods. The air intake temps of an engine @8000rpms on meth are roughly -30F!!! The cooling properties alone are usually good for 10% gain!!

Here is some cool info: I re-dynod my drag car recently with 110 octane instead of the normal 116. We noticed almost a 20whp loss!! Again, like methanol, even though specific energies may be equal, burn qualities/rates are completely different.

This turned out to be a good thread...very rare to have an in-depth tech. convo on Drag!

 

I agree, good job deliberating that, I feel as though I just read a book thanks to you and Fabrik8 we need more posts like that

 

It makes my week when I can actually have a good discussion like this..

 

i enjoyed reading it. now how about you do a write up on Turbos,Superchargers,Nitrous and differnt fuels. Id love to read that as well.


thumbs up.


-Cheers


Jason

 

 

Sweet post, I didn't know jack about meth. Learned a lot on this thread.