Fun with TurboCAD (pic was bigger than expected)

F

FloridaRustang

Active member
Just a start, I'm learning how to do 3D stuff.

chamber.jpg


2 x 34mm Intake, 2 x 34mm Exhaust, 92mm bore (3.62"), lift of .590 shown, peak of the pent-roof is 12mm. Can't remember enough calculus to estimate chamber volume. :roll: Gets the idea across, though.

"Valves" are just 50mm long cylinders right now. Will have to shrink them a bit for actual passages.

Using TurboCAD v7.1 (9.1 or 9.2 is out now, picked this up cheap), no manual or tutorials so the learning curve is steep. Can't save to STL format, but it can do JPG, DXF, and DWG (among others).
 
Shrink the exhaust and increase the intake. 80% is a good rule of thumb (exhaust being 80% of intake).

As for the drawing.... My job is mostly 3D and I can't see exactly what is going on :)


-=Whittey=-
 
I just tried 35/32 (83%) and it fits fine. Vizard says that the closer the exhaust diameter is to the intake, the more efficient, though at 90% the gains fall off. Of course, the trade off is potential horsies lost because you didn't make the intakes bigger...

To compare stock 250 2-valve with this 4-valve:
250 Intake 44.164mm - area 1531.89 mm^2 - circumference 138.75 mm
250 Exhaust 35.306mm - area 979.01 mm^2 - circumference 110.92 mm

New Intake 2x35mm - area 1924.26 mm^2 (25.61% larger) - circumference 219.91 mm (58.5% larger)
New Exhaust 2x32mm - area 1608.50 mm^2 (64.30% larger) - circumference 201.06 mm (81.27% larger)

Of course, the .590 lift is insane. .450 would be serious high performance in this case (at least comparable to .600 lift on the stock 2-valve). And I'm going to try to incorporate the mechanical lift variator that Pattakon came up with. That would allow you to control the throttle via valve lift, and make a wild cam act better than a stocker at low RPMs.
 
It really doesn't matter as long as its about 90 to 80%. A great Aussie two valve 250 cross-flow polyspheric head with a set of cut-down 351 2v or 4V valves can have a valve diameter to bore ratio of 0.53 per inch or bore, right up with a Hemi. ( 30 thou over at 1.97" diameter valve/3.71" diameter bore = 0.53). In the evil metrics, 50.038/94.234mm.

The latest 330 cube (5.4 liter) Falcon GT engine has two 5.4 GT valves per cylinder from the new GT40 replica, and these are 37 mm for a 90.2 mm (? iirc) bore. This is equal to one 52.325 mm valve ( 2.06"), a valve diameter to bore ratio of 0.58 per inch of bore. The actual size of the exhast to intake area is less of an issue, 'cause the pentroof chamber is unshrouded, and flows superbly!

I did AutoCAD Release 13 back in 1991. Never got to 3d....natch!


So do you want cross sections of my alloy crossflow 250 Honda head now, Florida?
 
XECUTE":1fzehgzn said:
I did AutoCAD Release 13 back in 1991. Never got to 3d....natch!
Click to expand...
'91? 13? Surely you mean either ~1996 or perhaps AutoCAD 5? Hehehe.

I remember when 13 came out. My drafting instructor had to whine repeatedly to get Win95 put on our machines so we could run it (state run tech highschool). I also remember like 23 floppies to install it all :cry:


-=Whittey=-
 
uM, yes, 1991, it must have been AutoCAD 3!!!! On a 386SX it was a proper pregnant dog to use! This was the one where you could run script files using Edlin, the electronic line editor, and you could go away and get a cup of coffee when the screen did a slide show. Hatch commands would take out the program.

My friend at an Achitectual school has repetive strain injury from that little mother.
 
In 1991 it would have been AutoCAD R11. Trust me on this, I've been using it since R9. BTW AutoCAD R10 ran just fine on a 386SX with a massive 5 Meg on board, R11 never ran fine on anything. The even numbered releases 10, 12, 14 were all excellent. The odd numbers 9, 11, 13 and 2000 (which is really release 15) uniformly sucked. Thus far LT 2004 looks like the best version yet (the current full-house versions are completely out of my price range)
 
bah, Autocad sucks all together. i finally got Autodesk Inventor installed on my Dell Precision 340 workstation at work and i love it. Parametric 3D modeling is the way to go. i hope like hell i never have to use Auotcad on a daily basis again, but it looks like the 2004 upgrade is gonna get installed before everyone switches over to Inventor
 
just switched from 2002?3 to 2004 today not sure if i like it yet
yeah inventor is definatly the way to go for 3d it is so much easier than autocad
 
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