Maybe you just got it mixed up in your head, it happens to the best of us.

I mentioned the paint color as a joke, obviously, but you actually found a way for it to, technically, (maybe.....) affect power output! Bravo!! I got a pretty good laugh out of that one!


Keep the shiny side up!
Scott

 

Yeah that's most likely what happened, I was so confused by it I had to ask.

Everyone knows that black things absorb more "heat" aka 'infrared radiation' than white things. BUT....black things also emit it better. (same goes for smooth and shiny vs dull and rough) So a black painted engine will emit slighty more heat than any other colour of paint. Again I have no idea if it would even matter. I think it would be so insignificant. Everyone wants that extra 0.0000003847 of a HP....LOL

But hey I think the principal is sound. Check out the Leslie cube experiment. Same sort of dealio.

 

Power at rpm is what fascinates me.
An engine turning 7200 rpm fires the plug 3600 times every minute which is 60 times per second. That's the same rate that a fluorescent bulb fires (our 115/120 volt AC system alternates 60 times per second). That also means that each valve opens and closes 60 times per second. It's physically impossible for vacuum created by the downward motion of the piston to draw the cylinder full of air at this speed. The "ram effect" caused by the inertia of air moving through the intake tract is actually forcing air into the cylinder. This intake charge actually builds up a small bit of pressure when the valve closes and the air/fuel mixture wants to keep moving. At rpm's, it's a combination of push and pull that fills the cylinder...it's more like a bit of the charge is trapped in the cylinder on it's way through toward the exhaust, compressed and burned, then allowed to continue on its path.
Friggin' magic...

 

Yeah, it's hard for me to wrap my head around just how fast things are happening in a 4-stroke engine. It's amazing to me that an engine can even run at idle, never mind 7,000 rpm! And let's not even get started on motorcycle or Formula 1 engines.........


Keep the shiny side up!
Scott

 

Speaking of heat affecting power, Here's an interesting read I came across in a Hot Rod magazine last year... Everyone's heard of the water carburetor myth, but this "Smokey Yunick hot vapor engine" was a new one for me.


http://www.legendarycollectorcars.co...clusive-video/

 

If you guys want to get really crazy look at a gasifier. Runs off of any biomass. The vapours are then burned in the engine.

 

Well said.

Getting a grip on "the 5th cycle of a 4 stroke" is a cornerstone. Saint Vizard explains this well in Max performance SBC on a budget and elsewhere. I was first introduced to it as "pulse dynamics". Blow through a straw. Then suddenly block the flow with your tongue. The inertia will create a pulse of high pressure followed by a pulse of low pressure. (now we have a condition we can exploit!). The intake valve opens, piston pulls a pulse through the intake. The IV closes. Gasses pile up converting motion in to pressure. Combustion takes place. The now very hot pulse of gas exits the cylinder, pressure turns to motion, a high pressure pulse moves down the primary pipe. A low pressure pulse in tow. The IV opens as the EV is closing, exposing the pressure piled up behind the IV to the low pressure in the header primary, a pressure delta, Kick starting the cylinder fill. If we only had the low pressure of the piston limited by a very messy intake and absolute vacuum to fill the cylinder Motor Sports would suck! Tricky mechanics are employed to match the physics of the gas pulse dynamics to the mechanical needs of the engine. Flow path cross section and length are tuned to optimize the pulse dynamics and sonic waves bouncing around. Reflected sonic waves add another chapter to optimizing flow path (get out your slide rule!)

Hope this helps turn on a light bulb or two. I know I really enjoy learning stuff like this.

 

Technically speaking, it's physically impossible for a vacuum to draw air...
The air is pushed by the greater pressure in the intake.

One of the Vizard books has an interesting section about how much horsepower potential is lost if there is significant vacuum in the intake
at wide open throttle.
Something I hadn't thought about until I read it...

 

You beat me to talking about pulses. Most people never get that in depth to realize how they impact the whole system. The pulse help determine optimal intake and exhaust lengths and sizing to have optimal pulse movement and exiting.

 

David Vizard is a genius. The thing is many of his statements and philosophies are directed toward absolute maximum power. He is a regular winner at the Engine Masters competition and builds racing engines. The thing those building a street engine need to keep in prospective is that many times absolute maximum power is not your goal. LSA is a good example. 108 is the recommended LSA for a 383 build for best power. In most cases it is not the best for a street engine, especially an automatic. 110 or 112 is a better option in most cases. GM used a 114 on the performance Gen 1 engines. Why would GM do this? Better idle with a big cam, wider powerband, more vacuum, better fuel mileage among other reasons. You give up some peak HP but better streetability is the tradeoff. All builds are a series of compromises.

 

I absolutely agree.
If you read his books carefully you'll see he sneaks in stuff like that fact about wider LSAs being better for street engines.

I think one thing really lost in the mix is the idea that big overlaps don't work well with restrictive exhausts.
SWCDuke is big on that...

 

All of you guys have great points!

I am wondering if anyone knows how or can direct me to somewhere, in regards to sizing particular components. Like I mentioned, engines in general not just chevy 350's.

For example, Intake runner volume on heads is widely advertised. How do you know what volume you need/want for a particular engine (keeping in mind how that engine will be used)? What about how to determine the size of headers?

I am going to order one of David Vizards books, is there a particular one that has the math relating to these subjects? If there is a formula (or many) then it can be applied to any engine regardless of size, use, etc...

General theories are good background, but if you can't put numbers behind it you can't do a whole lot with it.

Maybe I am too crazy or too ambitious and biting off more than I can chew, but hey what fun is it if you don't try?

 

I'd read How to Build Horsepower volumes 1 and 2 and go as far as you want from there!