| [ Total Views: 601 | Total Replies: 5 | Thread Id: 96618 ] |
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 Camo
A.k.a.: Kev
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| posted on April 26th, 2012 at 07:33 PM |
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What compression does your worked N/A engine have
Hi all,
firstly, I am not after your compression ratio at all.
I am just curious as to what compression your modified N/A engine may have, non turbo engine of course.
Mine has an average of 175psi.
Thanks, Kevin
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on April 27th, 2012 at 06:06 PM |
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Mine has 200.
You can advance and retard the cam and
note significant changes in the cranking compression.
Naturally a smaller duration cam, or more static compression will increase the number.
I always remember Mick Atholwood (RIP) used to say a good rule of thumb
for a drag engine was to adjust the cam duration and position to aim for 200 psi.
Just for comparison, and peoples interest, my old supercharged 1715cc engine with low 7:1 comp,
and large duration cam only had 100 to 110psi.
| Quote: | Originally
posted by westi
That's mad Alan.
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Camo
A.k.a.: Kev
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| posted on April 27th, 2012 at 09:21 PM |
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Thanks Dave for your input.
Gives me something to compare to and for others 
Any idea what your compression ratio was with the 200psi?
Cheers, Kev
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Craig Torrens
A.k.a.: Craig Torrens
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| posted on April 27th, 2012 at 10:47 PM |
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Kev, your compression is fine
What was the lowest and highest ?
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waveman1500
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| posted on April 28th, 2012 at 12:51 PM |
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My old 1500 single-port had 100psi in #1,2 and 4 and 70psi in #3. That thing had definitely been worked, very hard for about 40 years!  Just for comparison. It still ran on all four just fine and I got it up
to an indicated 86mph on a straight bit of road. Admittedly, it was slightly downhill! That was in a 1970 Beetle.
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Sandy
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| posted on April 28th, 2012 at 05:43 PM |
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My 1835 has about 140 psi
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