Altitude and Carburator size selection and VE

[Polyhead]

Maybe this will save some hair.........

CFM will be the same but density will change - each cubic foot will have less air molecules so less fuel and less HP.   

The new jet diameter is equal to the original jet diameter times (new density/original density)^0.5 [raised to the 0.5 power]
So if you have a Ø0.1000 jet at 100% air density and B'ville gets you 82% air density then your new jet is Ø0.0906 [Jet area is 82% of original.]

Remember that formulas are only a guide as reality can will be slightly more complicated since carburetors are a volume solution for a weight problem.

This calculator has a jet correction routine and other useful routines for plotting various schemes to raise HP by lowering the weight of your wallet  :
http://www.amazon.com/Mr-Gasket-Street-Performance-Calculator/dp/B003DITJEY

Apps are less $$ so more $$ for HP! 

Android app: https://www.calculated.com/prd363/Hot-Rod-Calc-for-Android.html
iPhone app: https://www.calculated.com/64/prd360/Hot-Rod-Calc-for-iPhone.html

x2.

Some suggestions:

A/   Spend $39.00 on Larry Meaux's "PipeMax" header design and calculator program.
2/   Take the time to "properly" model your engine in the program.   This means measuring accurately, NO guessing.    Don't forget that: GIGO
d/   Change the model to identify "trends" within the basic scope of your engine build.

WHY GUESS WHEN YOU COULD KNOW?   This method reduces the cost of parts that end up being "unsuitable" because of a guess about size/sizing.

However, if most of the pleasure you derive from your build is to try different things to see what works and what does not, by all means do it that way.    Lots of significant development has been done in that fashion previously.   I, for one, will not argue about the certainty of testing, specifically, testing to destruction.    I just don't want to be the one paying for it.

 
Fordboy

Doesn't run on Linux.  I will use nothing else.  Microsoft and apple can both suck it.

[Milwaukee Midget]

Doesn't run on Linux.  I will use nothing else.  Microsoft and apple can both suck it.

You've already painted yourself into a corner with your engine choice.  A misguided tool choice that limits yourself to software that runs on Linux is simply going to see you on the sidelines come August. 

In the world of orphaned engines, this is the cost of doing business - putting prejudice aside and using what works.

[SPARKY]

LOL

[Polyhead]

Doesn't run on Linux.  I will use nothing else.  Microsoft and apple can both suck it.

You've already painted yourself into a corner with your engine choice.  A misguided tool choice that limits yourself to software that runs on Linux is simply going to see you on the sidelines come August. 

In the world of orphaned engines, this is the cost of doing business - putting prejudice aside and using what works.

If it won't run on Linux, I don't need it.  I've used nothing else since 2000, and before that it was Amiga OS.  Misguided as in, it never breaks or misguided in that the I/o performance is far superior?  Oh, I know, misguided in my choice of file systems.  Pretty tough in life to have to run something as high performance and reliable as reiserfs.  Maybe you mean how misguided in having a choice in gui design theory and not being stuck with whatever the vendor chooses.  Does suck to be me, using a gui that works.  Oh sure xfce looks dated so it must be horrible.  Windows, file requesters, who needs that? 

Seriously... What kind of world do we live in that has made Unix the sane choice?  Now that is crazy.

What the hell would I know, my junk works.

[Milwaukee Midget]

I'm simply saying the choice of OS is limiting your choice of software.

That said, there is very likely a Linux based program that will get you the numbers you seek.

But like the Poly, you'll be in lightly charted territory.

[Polyhead]

I'm simply saying the choice of OS is limiting your choice of software.

That said, there is very likely a Linux based program that will get you the numbers you seek.

But like the Poly, you'll be in lightly charted territory.

More like, just like the poly, I do it myself.  Not only am I a machinist, I'm not too bad with C. Been a while since I dabbled with m68k assembly though... Maybe I should do it up for the Amiga just to annoy people   

[Speed Limit 1000]

Time is the only thing you can not get more of, some people try to use it wisely

[Polyhead]

Time is the only thing you can not get more of, some people try to use it wisely

And accomplish what exactly?  This game ends the same for everyone.  Using time wisely.  Many would tell you it's all better spent on your knees in prayer.  Wisdom is entirely relative and far less subjective than "wise" people ever want to admit.  Wisdom is a farce.  You show me someone that thinks what they are wise and I'll show you someone ignorant in the extreme.

Too much philosophy (all of which is bullshit), not enough tech.

[hotrod]

Pipemax will run on linux in the wine emulator.

http://www.oldjohnno.id.au/page3.html

[Polyhead]

Pipemax will run on linux in the wine emulator.

http://www.oldjohnno.id.au/page3.html

Right, but wine is only legal to use if you own windows because so much of what wine does relies on Microsoft owned libraries.  Well if that were the case I would just dual boot the machine.

Also I've not had a good deal of luck with Gentoo's wine package.  They're are several dependencies that conflict with things needed by xfce.  This is because wine uses gtk3 and xfce uses gtk2 and some bits of gtk2 and 3 will not coexist readily.  I'm not a fan at all of gnome 3, so that leaves me with choosing either xfce or lde fit window managers. (Even Linus calls gnome 3 an unholy mess)

My install is quite complex as I also refuse to use systemd and that leads to me needing to patch around things.  Hopefully systemd soon dies and we can get away from that fad.

So... Just making the gnu end of things fit my standards is a bit cludgey.  Making further cludges to get it to run Windows software is not something I care to ever do.  And even at that it'll only work on x86 hardware and not all of my hardware is x86 based.  There are some ultra  SPARC and MIPS hardware thrown in for good measure.

[wobblywalrus]

A year or so ago I was at a local car show.  This hot rod had a V-8 engine and above it were two parallel log like cylinders about 3 inches wide and 14 inches long.  The cylinders were connected to each inlet port on the head with one manifold for each pot.  One log connected to the right bank and the other to the left.  There were nice carbs on top of each log midway between the ends.

The gent who owned the car saw me looking at this and we talked about it.  Each port-to-log manifold was shaped to provide the optimum length and volume to give the desired primary intake harmonics.  The log was sized to give correct Helmholz resonance for secondary intake harmonics.  I asked him if it worked.  He looked at me with that twinkle in his eye that said more than words.

Occasionally I will see old race cars tuned with this method for their exhausts.  All equal length headers dump into a cylindrical collector before changing direction and going out of the tail pipe.

Chrysler was ahead of their time when it came to intake and exhaust harmonics.  It would be worth it to bolt that log on for a dyno run.

[Polyhead]

A year or so ago I was at a local car show.  This hot rod had a V-8 engine and above it were two parallel log like cylinders about 3 inches wide and 14 inches long.  The cylinders were connected to each inlet port on the head with one manifold for each pot.  One log connected to the right bank and the other to the left.  There were nice carbs on top of each log midway between the ends.

The gent who owned the car saw me looking at this and we talked about it.  Each port-to-log manifold was shaped to provide the optimum length and volume to give the desired primary intake harmonics.  The log was sized to give correct Helmholz resonance for secondary intake harmonics.  I asked him if it worked.  He looked at me with that twinkle in his eye that said more than words.

Occasionally I will see old race cars tuned with this method for their exhausts.  All equal length headers dump into a cylindrical collector before changing direction and going out of the tail pipe.

Chrysler was ahead of their time when it came to intake and exhaust harmonics.  It would be worth it to bolt that log on for a dyno run.

Well the logs are still on it...  in theory, if I position an X pipe at the right point, the flow would be nearly as good as headers anyway, I could get my scavenging that way.  The plan is to run the car stone cold stock, 2bbl intake and get some dyno numbers off of that.  That's for the magazine article.  I got some help from some persons that edit a certain magazine.... So... expect to see the car in one of the most low brow automotive publications.   Yes, the money for the dyno pulls will be comming out of my pocket.  But I gots to know!

[RichFox]

you talk bout doing things the hard way. Fine. So I think you should be building your own intake. No rule says it needs to be aluminum. Mine are mostly steel cause it's easier to work with for me. And sets you free from the Dairy Queen cruiser intake

[Polyhead]

I already have an intake that'll work fine.  Headers I don't.

I don't have any place to do any welding at the moment anyway.  With things slow at the machine shop, the bosses are all out of here at 3:30, so no staying late and doing up a set of headers or an intake.

I'll save the intake building for my adventures in mechanical injection.

What have you got against dairy queen anyway?

[RichFox]

I like A&W better