CR Calculator Problems

[sprucegagt]

Yeah, you can still enter notes into the block, but it doesn't pass them through the code. It appears its an AJAX/JavaScript issue in FireFox that I need to do more digging on. I basically just editted code that I got from somewhere else that is SUPPOSED to be FF compatible, but it appears its not working that way.

As far as your question Andy, I have found mixed results on the forum. I ended up using the value that made the stock CR come out close to specs. But that could be wrong. I really need to put a disclaimer on there that the listed stock values are for reference only, and exact values must be used to determine the true CR of the engine. This isn't directed at you Andy, but sometimes I think some people take stuff like that as final answers, when there can be alot of differences between what is listed an what the person actually has (for head CC volume for example).

Oh I'm not taking it as an exact value, just a general reference. But thanks for looking into it.

[SappySE107]

ok, here we go.

3400. 28.6cc head, 28.6cc piston, -.020 deck height, 3.310 stroke, 3.622 bore, 3.750" head gasket bore, .060 thick, 9.64:1 compression.

3500. 32.4cc head, 24.5cc piston, -.010 deck height, 3.310 stroke, 3.700 bore, 3.800" head gasket bore, .060 thick, 9.8:1 compression.

These are my measurements and compression was calculated in dynomation for me.

[torq455]

entered 3400 with a piston deck clearance of .0065 and got 9.07 CR. the 3400 chamber is right on. about 4 years ago when you ported my heads and polished the chambers, i had one cc'd at 29cc.

[SappySE107]

use my values, they are as accurate as you are going to get for stock. .0065 must be camaro pistons?

[torq455]

that's the default value for the 3400 not 3.4. -shrug- damn, go to bed!

[bszopi]

Ok, try the new link to FF compatible calculator...

http://www.60degreev6.com/apps/oldstuff/crcalc.php

[bszopi]

ok, here we go.

3400. 28.6cc head, 28.6cc piston, -.020 deck height, 3.310 stroke, 3.622 bore, 3.750" head gasket bore, .060 thick, 9.64:1 compression.

3500. 32.4cc head, 24.5cc piston, -.010 deck height, 3.310 stroke, 3.700 bore, 3.800" head gasket bore, .060 thick, 9.8:1 compression.

These are my measurements and compression was calculated in dynomation for me.

Ok, the db has been updated for those values. The site CR calc matches the 3400 CR, but gives 9.79:1 instead of 9.8:1 for the 3500. But I think its close enough. Thanks Ben.

[IsaacHayes]

Warning: Division by zero in /home/wottech/public_html/apps/oldstuff/crcalc2.php on line 50

[ForcedFirebird]

ok, here we go.

3400. 28.6cc head, 28.6cc piston, -.020 deck height, 3.310 stroke, 3.622 bore, 3.750" head gasket bore, .060 thick, 9.64:1 compression.

3500. 32.4cc head, 24.5cc piston, -.010 deck height, 3.310 stroke, 3.700 bore, 3.800" head gasket bore, .060 thick, 9.8:1 compression.

These are my measurements and compression was calculated in dynomation for me.

Did you sufrace mic the deck height? I measure the compressed thickness of the 3500 gaskets and they are .060". You would think GM would make the gaskets match the pistons for a .040" quench?

Are you guys using the larger 3500 gasket bore of 3.8"? I confirmed that, and the .0095-.01" 3.4 pistons protrusion.

[ForcedFirebird]

OK, got as much as .020" and as little as .010" depending on how straight the piston is in the bore. Centering the piston in the bore gives .010", and the extra quench must be there to compensate for piston rock. This means the 3.4 .040" gaskets should work in theory, and possably it was the duration in Dave's cam that cause the contact between the exhaust valves and piston.

[IsaacHayes]

Ok so do the 3.4l RWD pistons protrude .0095 or are under the deck .0095 ??!?!?! And yeah the piston will rock back and forth, so I guess take the middle number.

Well Dave is using stock 3500 block and pistons too... so he already had stock quench then made it smaller...

If we use 3400 lower end, camaro pistons, and 3500 heads, the quench is too big with .060 so .040 would bring it back to normal more, but then compression goes up higher. I wonder if you could CNC remove some material from the camaro dish enough to lower it to 11.5:1 with .040 camaro gasket without compromising the pison???

[ForcedFirebird]

The Camaro pistons and the 3500 pistons are almost identical. The CR calculator and using the distance from the journal to the deck, the Camaro pistons should be .0095 and I measured exactly .010" with new bearings.

I think even the .040" gaskets are cutting it close on the 3.4, those pistons rock just as much, but they also didn't rev as high as the Gen3's. That combined with the fact that the iron heads are non-interference, it makes sense that they could get away with a tighter quench.

From what I can gather about all this info, is that the .060" gaskets are ideal for most of the 660's.

[IsaacHayes]

Yes, but we are trying to get good quench with 3500 heads on a 3400 with camaro pistons and .060 head gasket... from what I can tell that makes compression 11.55:1 (good) but quench is .050 (too big, so you will see ping).

[ForcedFirebird]

11.5:1 if you use 3500 gaskets, they have a .05" bigger bore in the fire ring I also removed some material in the chambers and polished them.

Not trying to get too off topic, but didn't I see that there are .045" gaskets?

[bszopi]

Well, its an issue with FireFox passing the values. It makes no sense to me why IE sees the values and passes them just fine, but FF doesn't see it. I am still going to try a few things, but I really have no urge to rewrite the program again. IE still has a 60/40 lead on visitors...