With the blessing of the moderators, I want to go down in CamaroZ28.com history as having the longest and most
informative post EVER!

Some of you know where this inspiration is coming from as
a result of my previous post titled "Advanced Engine Technology
Sources".

Who wants to play and help me learn?

A wise man once told me, an engine builder will design an engine
from the characteristics of the camshaft...

Another wise man once told me, an engine builder will build from
the head design.

So? I'm not so sure I agree with either of them? Let's play
a cool game:

Your team manager wants you to build a backup motor for
your seven second alcohol car. It's going to be naturally aspirated.

We're limited to 500 cubes, and 3 transmission gears.
The total vehicle weight with driver is 2200 lbs.
Anything else, the sky is the limit.

What is the first thing that comes to YOUR mind?

I want the best of the best to come along on this project with me.
From start to finish, I want to build my dream virtual motor and
driveline.

The first thing that I think of is power to weight calculation to
give me a 'ball park' figure of how much power this engine must
produce to break the 7 second 1/4 mile mark.

An online calculator gives me ~ 1300 HP at the wheel.

From that number, I know the engine must rev very high to make
that much power. We're talking high flow, large diameter runners, heavy cam and big valves.

Now I get stuck. A pro engine builder will look at the above info
and start calculating cam overlap, lift, duration, rod/stroke ratio,
head runner c.c., etc.

My very first question as stated above is: Where do I start?

Camshaft selection, Heads...neither?

Respond with your words of wisdom. Let's take these posts step
by step and learn from each other.

In one paragraph or less, what is your approach?

This will be a continuous post, so don't get too lengthy on your
reply.

Is this cool with the moderators?

 

Have you looked at Pro Stock recently? It's all been done!

6.72 @ 205 is the current record, I think.

500 cubes, gasoline, 2 carbs, no power adders and 2350 lbs.

hp outputs are about 1300+, or were a couple of years ago.

The technology is there. The development and production costs of these engines are VERY high, so extremely deep pockets are required.

You were correct about high rpm, around 10K. Also about an inch of valvelift and valve spring life at speed of about 1 run. Makes dyno testing tough!

IMO, your "wise men" aren't necessarily wise, and camshaft is probably the last thing to specify, not the first.

My $.02

 

I don't think too many of us here know much about alcohol race motors! Sharing what we do know might be interesting to a point, but it really has little applicability to a street hi-performance or street-strip setup. For one thing, we are talking an order of magnitude difference in cost. Another is that an all out race motor is not designed for any kind of longevity (beyond a quarter mile at a time), no concern for fuel economy, noise, emissions, etc. It's apples to oranges.

One design aspect that differs a lot from our motors is that a very light rotating assembly is used. This is done to allow very high rvs and rapid acceleration and is possible primarily because the design and materials aren't as cost sensitive and that they don't have to last very long. For example: aluminum rods are not suitable for street use, but are a favorite in drag race motors.

None the less, the cylinder heads are where most of the "black magic" is involved and what will really distinguish one NA race motor over another. A race motor of the type you are dreaming about might cost $75-100,000 with 1/2 of that in the heads and induction system.

Rich Krause

 

No, no...this is a 'Virtual' engine build-up.

A step by step download of your "brain" throughout
each 'stage' of engine design.

I know there are some smarties in here that
have built some good motors...I know there
are people in here that have access to info
that can shed some light on such a difficult
subject.

Don't be confused by my question...I'm not
building an alcohol engie, I want to learn what's
involved from A to Z and as technical as possible
please

 

Zero, my take on your recent threads is that you want to know everything without working to learn it. It just doesn't happen that way. In order to understand what is involved, you need to study the basics, as was pointed out in a previous thread. There is a reason engineering schools take four or more years to turn out someone who understands "how things work". That's when they start learning how to design machines.

You have access to the internet; do your own searching and reading. Invest some money in the books previously recommended, read and reread them. Noone knows everything from A to Z. (I'm only up to Q)

No flame intended, but if the gurus on this forum get "as technical as possible" you won't understand what they are saying. You need more fundamentals.

My highly opinionated $.02

 

Find someone who races/builds engines locally and hang out with them.
Hands-on will go a long ways in your search for knowledge. It'll also help you in understanding the basics of how an engine works.
As the old one said, invest some money in the books that were mentioned in the other thread. When you consider the fact that many spend 4+ years of rigorous curiculum gaining the knowledge you'd like to have... well, that should be a humbling thought for you. Be patient, be studious, be hands-on and invest in your education.

-Mindgame

 

Awww..you guys are no fun

With all due respect I do work very hard for what I know. I've
taken automechanics in school, re-built five small block Chev's
from the bearings to the paint...also have subscribed to National
Dragster magazine and watched every performance TV show
known to mankind

Internet is also a good resource for me, not message boards,
but performance sites and advanced forums such as this one
offer some great information.


I do have some buddies in high places...but they don't have time
to sit down and talk tech when running a business.

I do plan on purchasing at least one of the suggested books for
a start... see how that goes.


I guess I can't expect everyone to sit through a thread like this
from beginning to end, but it would have been cool to exchange
ideas about design.

Back to the books I go....

 

Hey,

I have one for you.

Go look at the Popular Hot Rodding Engine masters contest. What is going on there directly applies to you and your car. The rules make the game a "street" motor and with in normal specs of something more guys could build with the right knowledge.

www.enginemasters.com and the last two issues of Pop Hot Rodding and the one next month is going to be big on info and stuff you can pick up from. People used to think that a 200+cc intake port was not good for street use to do velocity, well you'll find out about that here too! Lots of little things, and the details of the parts are what you need to look at and how they all relate.

My experience didn't come from hanging out (we'll learned alot from my father), from school or from hands on stuff. I've learned alot of theory on my own over the last 16-17 years and get more and more in depth every day.

As for your engine............ Heads are the first thing you look at when given a engine goal, then match everything to what you need. Look at the rules of the 2002 contest (from above) and come up with a design before you see what combo won next month. Then think about what you are going to do for the 2003 rules and watch out how that pans out. I have to say that since it's a "street" engine contest you will learn alot more about the sacrafices you have to make in a engine design, one thing for another when you put these rules on it. It's not a mass production engine and it's not a full race engine but a combo of both. That arena is not very easy to play in, and it like anything else takes ALOT OF TIME AND MONEY TO WIN! The better the people in the contest get, the more time and money it takes to win.

BTW to win the 2002 contest you would have needed about $19,000 in the engine (even w/ price breaks you get from the sponsors) You could win it with basically off the shelf parts and not too much custom work.

That's my take on this question. Asking us about building a Pro Stock engine will not teach you anything, you will come away from that thinking that REALLY BIG PORTS, 500+cfm, 1.000"+ of valve lift and 10,000rpm is what it takes to make mean HP. That's not it. Try looking at the ft lbs per liter of a engine. That is where you will find some interesting technology. (BTW a BMW M3 makes 83 ft lbs per L(highest NA prodution car), and to win that contest you needed about 88-90 ft lbs per L, next year my guess is 92-100 ft lbs per L.) I pick that because RPM is $, ft lbs per L is a good design.

That's all I have right now. I think you need to really get to us on this when we are in the mood to answer it. Engine design is an experience thing, but there are basic rules that apply to everthing. I'll tell you that you have to get to certain levels to understand the really fine points of engine design, and I'm not likely to get into that with someone unless I feel they have a grasp on the basics to figure out how to get there on a particular topic.

This is a very long thing to discuss you are right, look at what I gave you, come up with a design and why you pick what you pick and I'll be happy to critque it over time. Remeber every part, dimension and spec counts so think about them. If you don't know enough, my questions about it will give you a good reason to look it up.

Let's start there.........

Bret

 

Look, it's like this...

An engine is an air pump. You've heard that a million times. How much power you make is COMPLETELY controlled by how much air & fuel you can cram in and how efficiently you can move the spent gasses out of the way to make room for the next incoming charge.

That means it's all about the heads.

A camshaft should be matched to the head, not vice versa and the block is really only there to hold the pistons to a nice linear course so they can transfer their kinetic energy to the rods, crank, etc...

The intake, cam & exhaust are all there to help the heads do their job.

I won't pretend to know a buttload about head design or camshaft specs, although I like to think I have a little bit of a clue. But what I said about how important the heads are...? You can take that to the bank.

 

I've actually got a used P/S motor, built by Reher-Morrison. No offense, but you'll have a hard time getting much info about these unless you buy one. It takes big money to find 5hp now, so no one's talking. I may or may not race this motor, since the maintinence cost is far more than other motors of mine that make more power. The frightfully expensive titanium valve springs last 10 runs if we're lucky.

 

Awesome Bret,

I'm already writing up my thoughts and reasons for why I selected
certain values/parts for my motor. I think getting a pro opinion
to reassure my thoughts is half the battle.

Wicked,

I would have to agree with your point about heads - especially
the part about the intake, cam and exhaust.

I do understand tuned diameter/length of the intake and exhaust
runners, as well as valve overlap to use the "momentum" of the
incoming air/exhaust gas to push and suck the charge into the
cylinder (*scavenging*).

Just like in electronics/audio with wavelengths, the lower frequency waves are resonant when tuned with a *longer*
diameter port.

At the resonant frequency (RPM) the port must release the
wave at it's peak (in-phase) to realize an increase in low end
frequency response.

I relate this to pressure waves in the engine.

I gave my friend some advice today, tell me what you all think...

My buddy Tom wants to build a 383 from his current 350 motor.
Heads will be his first purchase. I recommended a 200 cc runner,
2.02/1.60 valve and large chamber ~ 72 cc.

This motor will be built for street/strip and should run low 12's
naturally aspirated on pump gas.

I suggested a larger chamber as I was told it would respond to
higher RPM more effectively. As I understand, larger chambers
allow for better distribution of the charge (swirl) and prevents
the mixture from *shooting* out the exhaust during scavenging.

When the concern of low compression was voiced, I stated that
decking the block and using a thin compress head gasket would
give enough kick to the motor as a fair trade for the larger
chambers.

Comments please and thanks.

 

Heads, hands down.

And Lingenfelter concurrs on this point as well.

 

Good thoughts on the tuning effects of the ar charge, you have to understand physics with that but you have a good grasp on it.

200cc heads, I like 230cc heads on a 600+hp 383. That would need 2.08 valves.

The large chamber is good to get the CR down for street gas with a 383 and flat tops. Now the other thing is that if you do a very small chamber like a 50cc one and put a 22cc dish in the piston you will get a more concentrated chage which will need less overall timing to achive maximum efficentcy and you will make more power. Check out a Busch Series engine and you will find this.

Bret

 

http://www.rehermorrison.com/techTalk/indexStart.htm

That is darned good reading material with basic theories on engine design.

IRL engines make 650hp with 213cid so at 500cid with the same power to displacement ratio you should be able to get 1500hp or so natually aspirated. You didn't stipulate no 4 valve or even 5 valve heads Note: IRL engines are capped at 10,700rpm, you can make even more power with another couple of thousand rpm.