Can I calculate my compression ratio CR with these informations ?
#1
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Dec 2009
Location: Montreal,Canada
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
- Cylinder bore : 4.040"
- Stroke : 3.75"
- Head Gasket : 0.039"
- Chamber : 56cc
- Piston : -5cc
- Deck : -0.016"
I have 230 PSI of compression right now and with the numbers I have up here I end up with 12.97 : 1
Does it sound about right ?
I got my motor back in October and almost every week I ask the builder what is my compression ratio and I'm unable to get a answer , he must know since he is the one who suggested me to use a Fel-Pro 0.039" head gasket.
I have very bad service with these guys
- Stroke : 3.75"
- Head Gasket : 0.039"
- Chamber : 56cc
- Piston : -5cc
- Deck : -0.016"
I have 230 PSI of compression right now and with the numbers I have up here I end up with 12.97 : 1
Does it sound about right ?
I got my motor back in October and almost every week I ask the builder what is my compression ratio and I'm unable to get a answer , he must know since he is the one who suggested me to use a Fel-Pro 0.039" head gasket.
I have very bad service with these guys
![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
#3
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Dec 2009
Location: Montreal,Canada
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
What is missing for me to figure out the compression ratio ?
Static , Dynamic , which one is the one we all use ?
Like GM say the LT1 has 10.4:1 in stock form , is it static or dynamic ?
...
Static , Dynamic , which one is the one we all use ?
Like GM say the LT1 has 10.4:1 in stock form , is it static or dynamic ?
...
![Embarassed](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_emb.gif)
#4
9 Second Club
iTrader: (7)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
- Cylinder bore : 4.040"
- Stroke : 3.75"
- Head Gasket : 0.039"
- Chamber : 56cc
- Piston : -5cc
- Deck : -0.016"
I have 230 PSI of compression right now and with the numbers I have up here I end up with 12.97 : 1
Does it sound about right ?
I got my motor back in October and almost every week I ask the builder what is my compression ratio and I'm unable to get a answer , he must know since he is the one who suggested me to use a Fel-Pro 0.039" head gasket.
I have very bad service with these guys![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
- Stroke : 3.75"
- Head Gasket : 0.039"
- Chamber : 56cc
- Piston : -5cc
- Deck : -0.016"
I have 230 PSI of compression right now and with the numbers I have up here I end up with 12.97 : 1
Does it sound about right ?
I got my motor back in October and almost every week I ask the builder what is my compression ratio and I'm unable to get a answer , he must know since he is the one who suggested me to use a Fel-Pro 0.039" head gasket.
I have very bad service with these guys
![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
ok.....let me shed some light here.........your compression with those dimensions is.....11.80:1....thats based on the felpro 1074 gasket which im assuming he used its a .039 compressed thickness wit a 4.125 bore.......
thats a healthy amount of compreesion
![Grin](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_grin.gif)
now............for that whole dynamic vs. static thing........
static compression is the calculated compression ratio based off of volume only.....the total volume of cylinder space vs. the compression volume this is the number we all use and see liike a stock lt1 being 10.4:1 SCR (Static Compression Ratio)
dynamic compression is the determined amount of compression based off of intake and exhaust valve timing........personally dynamic compression is a joke.....alot of guys on here say its soooo important but its not......dynamic compression calculations do not take into account the actual air flow and volumetric efficency of the motor...........i can tell you now to ignore alot of what you hear on dynamic compression......seems these internet people love to talk dynamic compression....
if we tested our motors while they weren't spinning then dynamic compression would be a good useful tool..........but last time i checked my motor mad more power at 7500 than it did at 0
![Winky](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_wink.gif)
perfect example........my current 386ci has a SCR of 14.1:1 and my DCR is down in the mid 9's.....however my new setup will hopefully make around the 700fwhp mark.....DCR is a discussion topic only IMO.....
hope this helps!!!
![Grin](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_grin.gif)
#6
9 Second Club
iTrader: (7)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
![Secret2](https://ls1tech.com/forums/images/smilies/LS1Tech/secret.gif)
but yea chances are your pistons are designed for a 4.040 bore and are around the 4.0396 mark......depending on the material and the required piston to wall clearance desired from the manufacturer of the piston....
Trending Topics
#13
TECH Addict
iTrader: (1)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
That looks better. Yea the whole dynamic isn't just an internet fad. When I built mine my builder told me to pay more attention to dynamic rather than static but thankfully I would not let the static thing go so Lloyd Elloit cut the heads to 52cc to help me out on the static since the builder ordered a -16cc piston and then Lloyd gave me a cam to complement everything. Runs good now. lol
#17
8 Second Club
iTrader: (2)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
- Cylinder bore : 4.040"
- Stroke : 3.75"
- Head Gasket : 0.039"
- Chamber : 56cc
- Piston : -5cc
- Deck : -0.016"
I have 230 PSI of compression right now and with the numbers I have up here I end up with 12.97 : 1
Does it sound about right ?
I got my motor back in October and almost every week I ask the builder what is my compression ratio and I'm unable to get a answer , he must know since he is the one who suggested me to use a Fel-Pro 0.039" head gasket.
I have very bad service with these guys![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
- Stroke : 3.75"
- Head Gasket : 0.039"
- Chamber : 56cc
- Piston : -5cc
- Deck : -0.016"
I have 230 PSI of compression right now and with the numbers I have up here I end up with 12.97 : 1
Does it sound about right ?
I got my motor back in October and almost every week I ask the builder what is my compression ratio and I'm unable to get a answer , he must know since he is the one who suggested me to use a Fel-Pro 0.039" head gasket.
I have very bad service with these guys
![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
#19
9 Second Club
iTrader: (7)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
check out my case .........
my piston is .008 down the bore
i have a 60 cc chamber with BIG *** valves
a .027 gasket
a 7.5 CC dome piston
and .703/.711 lift
and i clear just fine......its tight but i clear............he will be plenty fine for PTV clearance
#20
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Dec 2009
Location: Montreal,Canada
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
My motor is already running and I have a baby emission camshaft in it : 223/230 .565/.565 112 LSA .
I'm using LE2 heads with specification :
( copy & paste from my built thread ) Fully Ported heads milled 0.030" with 0.56cc chamber, casting 10128374.
Manley 2.00/1.56 6000 series valves.
PAC 1218 bee hive springs (145 lbs seat and 340 lbs open)
Steel retainers and locks.
205 cc intake port flow about 275/190 CFM.
I'm using LE2 heads with specification :
( copy & paste from my built thread ) Fully Ported heads milled 0.030" with 0.56cc chamber, casting 10128374.
Manley 2.00/1.56 6000 series valves.
PAC 1218 bee hive springs (145 lbs seat and 340 lbs open)
Steel retainers and locks.
205 cc intake port flow about 275/190 CFM.