Compression
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- af2
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Re: Compression
OK one more time checking.
@ .300" 70cc
4.135" x 3.75"
.010" in the hole
.030" x 4.160" Cometic head gasket
@ .300" 70cc
4.135" x 3.75"
.010" in the hole
.030" x 4.160" Cometic head gasket
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Adam
Adam
Re: Compression
Well, that's coming up to 4cc of dome volume roughly the other way. So that changes things
Last edited by CGT on Wed Jan 22, 2020 12:02 pm, edited 1 time in total.
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Re: Compression
An NA engine at SCR of 17.0-1, will produce (at 20deg BTC) 230psi and 760deg F.
Lowering the SCR to 9.0 and running 25 psi boost will produce (at 20 deg BTC) 500psi anf 696deg F.
While the cylinder pressure under boost will be significantly higher, the temperatures will be somewhat similar.
And, if the boosted engine can be fitted with an efficient intercooler, inlet air temperature will be further reduced.
Inlet temperature at the begining of combustion is much more important than is pressure, except that pressure provides an
increase in air density.
We can always adjust boost as needed, but SCR is forever.
- Stan Weiss
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Re: Compression
@ .300" 70cc means you have no dome volume and 3.98 cc's extra. As 4.135 X 0.3 = 66.018 cc's
15.26:1 does not include any top ring volume.
Stan
Stan Weiss/World Wide Enterprises
Offering Performance Software Since 1987
http://www.magneticlynx.com/carfor/carfor.htm
David Vizard & Stan Weiss' IOP / Flow / Induction Optimization Software
http://www.magneticlynx.com/DV
Offering Performance Software Since 1987
http://www.magneticlynx.com/carfor/carfor.htm
David Vizard & Stan Weiss' IOP / Flow / Induction Optimization Software
http://www.magneticlynx.com/DV
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Re: Compression
My line of thought and questioning was in regards poor combustion due to the piston dome, as the combustion process can be very different from a boosted motor running at + 2 or more Atmospheres and NA motor with 17 to 1.
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
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Re: Compression
i know you have PipeMax .... so just use the Compression Ratio Calculator in PipeMax v4.50af2 wrote: ↑Tue Jan 21, 2020 8:05 pm Ok I am lost trying to figure out the static on this new build...... 3.75 stroke 4.135 bore. I have at .375" down 75 cc the head gasket at .040" and the heads 46 cc. I measured down .375 because of the domes. Thanks I have a head ache finding it out I am figuring 17:1 but making sure so I can get a good flow# for the injection set up.
PipeMax ( Compression Ratio Calculator ) :
- af2
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Re: Compression
Thanks Larry and Stan I'll have to look on pipemax. The heads are 46cc.
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Adam
Adam
Re: Compression
Do you have a leak? Did you figure out where your inconsistency is coming from? I know it can be deceiving from pics, but from looking at the pics its hard to believe that piston doesn't have positive dome volume
Re: Compression
Your first set of numbers I came up with 7.5cc effective dome volume...the 2nd set I got 4 cc of dish volume
Re: Compression
Exactly what I was thinking. Those pistons look very similar to the +4cc domed pistons we put in a buddy’s 4” bore block.
- af2
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Re: Compression
I went to .300" and got the burret better stabilized. Yes I am looking at almost 4 cc dome. Thanks a bunch!
Now how much HP will it make!!!! LOOOOL. So Kidding
GURU is only a name.
Adam
Adam
Re: Compression
Dunno about hp, but the max torque it'll make is 644 lb ft. It's up to you to get it all out.