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Old 03-18-2012, 04:56 AM
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checking compression

Hi I am wondering if someone could help me check my compression so I can figure out with my combination if I can run on 91 pump gas or if I need to run a higher octane. If you could please help me let me know what information I need to provide. I really appreciate this I have not yet ran the motor because I am not sure what I shud run. If you let me know what specs are needed I will post asap thank you.

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Old 03-18-2012, 05:41 AM
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Enter your info and you'll get the compression ratio.

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Old 03-18-2012, 09:54 AM
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Quote:
Originally Posted by 406MOUSE
If you let me know what specs are needed I will post asap thank you.
bore
stroke
piston crown configuration, cc's in eyebrows or dish.
piston compression height
piston deck height
gasket thickness
chamber cc's
complete camshaft specs including intake valve closing point @0.050" tappet lift
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Old 03-18-2012, 02:32 PM
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Checking compresson

Quote:
Originally Posted by techinspector1
bore
stroke
piston crown configuration, cc's in eyebrows or dish.
piston compression height
piston deck height
gasket thickness
chamber cc's
complete camshaft specs including intake valve closing point @0.050" tappet lift
engine is supposed to be about 410 smc

Bore: 30 over
Stroke: It is a 6 inch rod

this is the piston specification that i got with the motor they are Racetec pistons. i do have a picture of what the piston looks like if you would like me to email you a pic or somthing.

The actual piston compression is 11 to 1

Engine Information
Head type: 40/60 SHIFT
Bore diameter: 4.165 in
Stroke: 3.750 in
Rod length: 6.00 in
Displacement/cubic: 408.7
Comp distance 1.125 in
Ring Info
Ring Number: AT8165 (not sure if this helps)
Rail info
Rail number: 3.845-168
Wrist Pin Info
Pin Type: chamfered
Pin number: 927-2700-51-15c
Diameter: 0.927 in
Length: 2.700 in
Piston Information
Piston type: dome diameter
Diameter 4.1620 in
Weight: 456 grams
Deck to crown thickness: 0.220
Forging type: A4123F N/C
Dome Volume: -.400 cc
Gauge point: 0.200 in
Ring groove width
Top Ring: 0.0640 in
2nd ring: 0.0640 in
Oil ring: 02180 in
Land width
Intake- depth: 0.280 in ,angle: 23.0 degrees
Exhaust- depth: 0.280 in ,angle: 23.0 degrees

im not sure wat piston deck height is but i do not piston was flush with the deck if that helps.


gasket thickness im using mls 1144 fel pro
-gasket bore: 4.200"
-comp volume: 8.9cc
-thickness: .040"

i have AFR 210 heads with 75 cc chambers

the drive train is a complete roller
The camshaft is a solid roller specs are:
lift: .630
Lobe Centers: 106
intake opens at 21 degrees close at 52 degree
exhaust opens at 54 degree close at 22 degree

intake is 253 @ .050
0.0200 is 284

exhaust is 256 @.050
0.0200 is 288

i hope i answered everything you needed. even though i probably gave you Unnecessary information but i figure id give you all the info i had. I appreciate your help.

Thanks Joseph
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Old 03-18-2012, 06:28 PM
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I'm getting 10.96 static and 7.94 dynamic.

My dyno simulator shows spark knock at timing above 30* for 87 octane and over 32* with 91 octane.

It shows keeping timing at 30* max, just under 600HP and no knock on 91. Of coarse I may have something entered wrong somewhere.
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Old 03-18-2012, 06:46 PM
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Quote:
Originally Posted by 123pugsy
I'm getting 10.96 static and 7.94 dynamic.

My dyno simulator shows spark knock at timing above 30* for 87 octane and over 32* with 91 octane.

It shows keeping timing at 30* max, just under 600HP and no knock on 91. Of coarse I may have something entered wrong somewhere.

O ok cool thank you yea I have no idea on how to figure this out I just want to know what it is so I know what octane I need to run if 91pump gas will not work and want to know what I should set the timng at if I can run pump gas or if it needs to be race gas.
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Old 03-18-2012, 06:57 PM
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The program calls the knock index between 1 and 2 the "grey" area where its not sure if knock will occur.

Locking out timing at 30* shows an index less than 1 but it may go more with no issues.
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Old 03-18-2012, 07:10 PM
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Quote:
Originally Posted by 123pugsy
The program calls the knock index between 1 and 2 the "grey" area where its not sure if knock will occur.

Locking out timing at 30* shows an index less than 1 but it may go more with no issues.
O ok so u think if I set timing between 30-32 I may be ok on 91 with no knock? Should I lock the distributor timing out? Or what should initial be set at if I don't lock out timing?
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Old 03-18-2012, 07:24 PM
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Quote:
Originally Posted by 406MOUSE
O ok so u think if I set timing between 30-32 I may be ok on 91 with no knock? Should I lock the distributor timing out? Or what should initial be set at if I don't lock out timing?

I think you should try it up a grade without pushing on it too hard to see if it knocks.

As I said, the simulator calls it a "grey" area. It may or may not ping. If the timing can be set up to 36* w/o knock, its good for about 20HP more.
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Old 03-18-2012, 07:30 PM
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Quote:
Originally Posted by 123pugsy
I think you should try it up a grade without pushing on it too hard to see if it knocks.

As I said, the simulator calls it a "grey" area. It may or may not ping. If the timing can be set up to 36* w/o knock, its good for about 20HP more.

O alright what makes it a grey area? Is it jus my combo
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Old 03-18-2012, 09:12 PM
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Its a grey area to the dyno simulator I use.

The simulator is not sure.
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Old 03-18-2012, 09:30 PM
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Quote:
Originally Posted by 123pugsy
Its a grey area to the dyno simulator I use.

The simulator is not sure.
K thank you very much tht will be aswsome if I can run on 91
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Old 03-20-2012, 12:44 AM
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will i be able to run on pump gas??

I was wondering if anyone else had any other calculations on what the actual compression may be to figure out if I can run on pump gas and what timing should be set at.

Thanks
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