help me learn more about engines...

[KiD-ViD]

I am not all that new to cars or engines but there are some things I want to read up on. how cam duration, lift, and seperation effects rpm range and other things. also the difference between single and dual plane manifolds. port matching...about how too big of a port hurts your power. etc. anyone know where I can look up these things. also I am looking for desktop dyno so I can play around with it and learn what parts compliment eachother and other things like that. anyone know where I can get it? I have had a really hard time finding it. thanks again for your help.

[Guest LIghtningZ]

What's up Kid! you can start be maybe getting yourself a copy of this months Hot Rod Mag the did yet another cam choice Write up, every time the do a cam related subject they do a pretty good recap. you should have dropped into Stockton for Lincoln center live tonight got a chance to meet Donna from here on HybridZ ( sorry Donna had a brain fart with your posting name Oop's) Shes got a clean 76'.

[grumpyvette]

here this will get you started,

 

cams

 

http://www.newcovenant.com/speedcrafter/tech/camshaft/1.htm

(theres 10 lessons ., read them all)

 

http://www.howstuffworks.com/camshaft1.htm

intakes

http://victorylibrary.com/mopar/intake-tech-c.htm

 

compression,

http://victorylibrary.com/mopar/cam-tech.htm

 

oil

http://www.micapeak.com/info/oiled.html

 

pistons/rods

http://www.babcox.com/editorial/us/us20114.htm

 

http://victorylibrary.com/mopar/rod-tech-c.htm

 

http://www.engr.rutgers.edu/~llongo/8K.html

 

headers

http://www.geocities.com/MotorCity/Track/6992/vizard.html

 

http://www.ssheaders.com/header.htm

 

hp/torque

http://www.carcraft.com/editorial/article.jsp?id=868

 

basics

An internal combustion engine burns a mixture of fuel and air in an enclosed space. This space is formed by a cylinder that's sealed at one end and a piston that slides in and out of that cylinder. Two or more valves allow the fuel and air to enter the cylinder and for the gases that form when the fuel and air burn to leave the cylinder. As the piston slides in and out of the cylinder, the enclosed space within the cylinder changes its volume. The engine uses this changing volume to extract energy from the burning mixture.

 

The process begins when the engine pulls the piston out of the cylinder, expanding the enclosed space and allowing fuel and air to flow into that space through a valve. This motion is called the intake stroke. Next, the engine squeezes the fuel and air mixture tightly together by pushing the piston into the cylinder in what is called the compression stroke. At the end of the compression stroke, with the fuel and air mixture squeezed as tightly as possible, the spark plug at the sealed end of the cylinder fires and ignites the mixture. The hot burning fuel has an enormous pressure and it pushes the piston strongly out of the cylinder. This power stroke is what provides power to the car that's attached to the engine. Finally, the engine squeezes the burned gas out of the cylinder through another valve in the exhaust stroke. These four strokes repeat over and over again to power the car. To provide more steady power, and to make sure that there is enough energy to carry the piston through the intake, compression, and exhaust strokes, most internal combustion engines have at least four cylinders (and pistons). That way, there is always at least one cylinder going through the power stroke and it can carry the other cylinders through the non-power strokes.

 

http://www.howstuffworks.com/engine.htm

[grumpyvette]

things to keep in mind!

 

(1) your normally limited to makeing about 1.25hp per cubic inch of displacement unless expensive high rpm parts are used or power adders like nitrous are used

 

(2)hp= torque x rpm/5252 so.....

400 ft lbs at 3000rpm=228hp

400 ft lbs at 5000rpm=380hp

 

get the IDEA, the higher in the rpm range you make max torque the higher your hp will average!

 

(3)looking at cylinder head flow numbers

((.257 x cfm at max cam lift x number of cylinders = hp POTENTIAL))

so...you can normally make ABOUT a MAX POTENTIAL HP of

411hp with heads that flow 200cfm

514hp with heads that flow 250cfm

617hp with heads that flow 300 cfm

 

(4)all parts in an engine MUST be matched as to the ONE rpm range that your trying to make max hp in..... if you mis-match the rpm range of the parts the results will be far lower than the lowest rpm level of the least effective parts!

(5) by far the most comon mistake is buying DEALS on parts that don,t match the rest of the parts in yout engines rpm range or not matching all the parts in the engine to a planned rpm range

(6) the cross over point between useing a dual plane intake and a single plane intake is approximately reached at 3500 rpm and 230 deg@.050 cam durration or put another way if your engine spends almost all its time below 3500rpm and your cam has less than 230@.050 durration a dual plane intake will work best, if you spend almost all your time with the engine spinning OVER 3500rpm and your cam has more than 230@.050 durration a single plane intake will be best. this of course assumes your smart enough to know that the cam durration must also MATCH the ENGINES intended RPM RANGE and youve matched all the parts to the cams rpm range(the cam is the brains of the engine and determines what rpm range all the other parts should match, so FIRST PICK the rpm range/hp goal,

pick heads that flow enough air to meet that goal,

pick a cam that matches that goal

and pick all the other parts to match the heads and cam

 

buy these FIVE books, it will be the best money you ever spent, read them, and you will be miles ahead of the average guy.

HOW TO BUILD THE SMALL BLOCK CHEVEROLET by LARRY ATHERTON&LARRY SCHREIB

.

HOW TO BUILD MAX PERFORMANCE CHEVY SMALL BLOCKS ON A BUDGET by DAVID VIZARD

.

JOHN LINGENFELTER on modifying small-block chevy engines

 

how to build & modify CHEVROLET small-block V-8 CAMSHAFTS & VALVTRAINS BY DAVID VIZARD

 

SMOKEY YUNICK,S POWER SECRETS

[danj]

Grumpyvette

 

Thanks for the refresher course in engine basics and the excellent reference sources. These should be on everyone's favorite web site lists. I purchased 4 of the 5 recommended books from Amazon.com several months ago and they are really good reading. Glad to see you are a regular poster to this site again after surviving your recent family wedding.

 

DanH

[grumpyvette]

good point about the dynamic compression being important!

heres how you figure that out,

 

http://victorylibrary.com/mopar/cam-tech-c.htm

 

http://cochise.uia.net/pkelley2/DynamicCR.html

(the software program is at the bottom of the page)

 

heres something about intakes

http://www.bgsoflex.com/intakeln.html

 

http://www.engr.colostate.edu/~allan/fluids/page4/effarea/effarea.html

 

heres something about exhaust

http://www.engr.colostate.edu/~allan/fluids/page7/PipeLength/pipe.html

[KiD-ViD]

I have been reading thoes pages and thinking about what you said. one thing I havent found out yet is how to find out the cfm a head can flow. is this directly related to the CCs via a formula or somthing or do you just have to flow test the heads? also if it is the flow test way then is it different for each head or is it the same for all heads of the same type (perhaps there is somewhere where I can read and compare the flows.) I am looking to build a 383 for my z. I am thinking 500 hp/tq would be great. it isnt going to be a daily driver but I would be driving it on the street alot. I want to run pump gas. it will be mainly used for drag racing but I might want to take it to a road course if I get the chance. (wont likly happen) so dont take road racing into the figure much I will just focus on dragging for now. thanks again you guys are so helpfull.

[Kevin Shasteen]

The question you probably dont realize your are dancing around is the distinction between "Pressure & Velocity".

 

When modifying an engine airflow characteristics you will always concern yourself with three aspecs:

 

1) Temperature..(moisture content of the air)

2) Velocity.....(speed of the air)

3) Pressure.....(Density of the air)

 

Sometimes in order to understand the intracacies of the engine it is helpful to understand the hard and fast rules.

 

Hard and fast rules of a cylinder head's ability to flow air are:

 

1) Small Ports = 165-185cfm

2) Medium Ports= 185-195cfm

3) Large Ports = 195-and above cfm

*NOTE: These flow rates will apply to Small Block V8's

 

If you are going to run on the street then small ports to medium ports will be the trick. If you are going to frequent the dragstrips often then medium to large ports are what you want.

 

The cylinder heads ability to be "Efficient" depends on the Volumetric Efficiency of that engine: Intake Air System, Fuel Mixture System, Cylinder Head Ports and Exhaust Ports/System. (How big is your bank account basically defines your VE% expectations)

 

If you wish to read for future understanding you should turn to David Vizards book on Modifying SBC Cylinder Heads. Turn to pages75 and read the side bar on "Power Limiting Port Area"....read it till you understand it; you may have to read it a dozen times till it finally clicks.

 

Also turn to page78 and read its sidebar on Flow and Peak Power. In both of these you will be using formulas w/constants. In the page78 sidebar the constant for the displacement is confusing. What he didnt tell the reader which must be "figured out" is that the baseline constant is [350]. Any displacment smaller is divided by the 350 figure while any displacement larger will have the 350 divided into the larger number. Such as your 383 you would do the following, like so:

 

383 / 350 = 1.09

 

Read both those sidebars add grumpy's formula for cfm and Lingenfelters suggestion on the E/I% Index, which simply states your exhaust ports should flow 75% of your Intake port numbers for a competitive engine.

 

If you are worried about over building your engine for the street then you really need to understand the math process on Dynamic Compression Ratio's-see Ed Staffel's book I mentioned earlier as it deals with the pump gas, race gas/Dynamic Compression Issue relative to Static Compression Ratio's. I really feel it is the bridge that brings everything together.

 

Gooood Luck/and have fun.

 

Kevin,

(Yea,Still an Inliner)

[Kevin Shasteen]

I would have to say "Salute" to the grumpsters recommendations. The only other thing I could add as far as book recommendations are concerned would be these two:

 

1) "High Performance Camshafts" Vol.11 from the 'Best of Hot Rod' series. Published by CarTech w/Copywrite Date of 2000.

 

2) "How to Build Max Performance Chevy Rat Motors" by Ed Staffel. Published by CarTech w/Copywrite Date of 1996

 

I like the first book because it literally walks you thru the past up to the current data on camshafts.

 

I like the second book not because it is about big blocks but because on Page#112 it gives info on how Dynamic Compression Ratios effect your choice of pump/race fuels requirments and has an accompanying graph of the Piston Location on page#108. The location of the piston is imperative as this location, when the Intake Valve Closes, determines the Dynamic Compression Ratio.

 

Something I would also add; what I found confusing when I first began attempting to understand engines was no matter what people told me it always seemed to come down to "Me having to [TRUST] someone else's advice".

 

This is not bad, providing that someone is someone you could trust. What I discovered is basically the powerflo of building an engine that Grumpy outlined:

 

1) Choose the Intent of the Car and stick to it

2) Pick a Displacement

3) Intent of Car determines needed power band rpm

4) #3 will determine what cam profile is needed

5) #4 will determine all other needed engine components

 

What I found in most articles and books (which I didnt like), was that an "Implication" existed, in that it was normal for one to build an engine and then "HOPE" that your build was a good one. In other words, build the engine-Then [guess] at what camshaft you would need on the advice of someone you never met (camshaft tech lines).

 

In reality; as grumpy said, your cam is the brain by which all else is determined....relative to the displacement of the engine....relative to the intent of the car.

 

The missing link to my quagmirical dilemma was the Dynamic Compression Ratio. I'm not referring to the "Pressure" as in a compression test but rather the "Volume" that exists in the cylinder above the piston after the Intake Valve Closes relative to the "Volume" above the piston once it reaches TDC. It is this Dynamic Compression Ratio that determines what Static Compression is needed to maintain the proper airflow velocity at any given rpm; and will also determine what range within the rpm's that your powerband will manifest itself.

 

Before coming to the understanding I now have I remembered manytimes feeling like I was on the outside looking in; but I kept at it till one by one, the light bulbs began flickering on till they began staying on....but for me, I found that the Dynamic Compression Ratio correlated to the Piston Map Graphs, was the key missing ingredient that most performance articles failed to teach, research or talk about.

 

Dont give up & stick to it; it isnt that hard once you have a basic understanding that all components of an engine are basically ratio's of somekind being factored into ratio's of other components. It is this inter-relationship of ratio's that determines a good build -vs- a bad build.

 

Hope all that made sence.

 

Kevin,

(Yea,Still an Inliner)