13:1 compression
11-09-2009, 10:38 AM
#2
Are you trying to do this with the stock components? If you are, you would have to mill the heads a LOT and then probably flycut pistons with any kind of decent size cam. It would we a lot easier to go with some aftermarket dome pistons. Are you planning on building a race car? That kind of compression won't run on pump gas. Let me know what you are doing and I'll see if we can get you where you are wanting to be!
Jon
Jon
11-09-2009, 08:03 PM
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Thanks for the info. Not planning on racing so 13:1 is out for me. Do you have any other suggestions for the engine? And yes it is completely stock.
11-12-2009, 02:48 PM
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depends on how much you want to spend... A lid is usually the first step for most when they start to mod their car and can be had for ~$100. Long Tube headers, ORY and cat-back wake the car up quite a bit. Depending on the year of your car (98-00) a LS6 intake would do you some good from there. If you have a 01-02 car GM did something right and already equipped your car with a LS6 intake 
. You should probably start worrying about suspension at this point. SFC's will definately stiffen your car and you will not have to worry as much about body flexing. LCA's are good to get as they will help you launch the car a little better.
As stated it all depends on how much you want to spend. With stock untouched heads and a cam, you can turn the car in for low 12's with the supporting bolt on's.
Really we can't suggest a whole lot more than that without you giving a little more info, like what your intentions are with the car. Do you want to just have a little more power in a daily driver, or are you looking for something you can take occasionally to the track? maybe a full out race car? the possiblities are limitless as this platform is very versatile.
. You should probably start worrying about suspension at this point. SFC's will definately stiffen your car and you will not have to worry as much about body flexing. LCA's are good to get as they will help you launch the car a little better. As stated it all depends on how much you want to spend. With stock untouched heads and a cam, you can turn the car in for low 12's with the supporting bolt on's.
Really we can't suggest a whole lot more than that without you giving a little more info, like what your intentions are with the car. Do you want to just have a little more power in a daily driver, or are you looking for something you can take occasionally to the track? maybe a full out race car? the possiblities are limitless as this platform is very versatile.
11-12-2009, 03:18 PM
#5
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^^ great answer
For technical info...
13:1 compression means that the engine compresses the air/fuel mixture to 1/13th the size of the piston bore.
On a stock LS1 the cubic inch displacement of the motor is 346 CID so about 43.25 cubic inches per cylinder when the piston is all the way down. When it is all the way up that volume shrinks to about 4.28 cubic inches. 43.25/4.28=10.1 or 10:1 compression. In order to boost the compression ratio you must either increase the larger volume or decrease the smaller volume. Thats what the first reply was refering to when Jon suggested a domed piston or milling the head. Both have the effect of reducing the combustion chamber volume so that the compression ratio goes up.
For pump gas here's a general rule of thumb:
Octane: 87 89 91 93
Iron Head CR: 8:1 9:1 10:1 10.5:1
Aluminum CR: 8.5:1 9.5:1 10.5:1 11:1
For technical info...
13:1 compression means that the engine compresses the air/fuel mixture to 1/13th the size of the piston bore.
On a stock LS1 the cubic inch displacement of the motor is 346 CID so about 43.25 cubic inches per cylinder when the piston is all the way down. When it is all the way up that volume shrinks to about 4.28 cubic inches. 43.25/4.28=10.1 or 10:1 compression. In order to boost the compression ratio you must either increase the larger volume or decrease the smaller volume. Thats what the first reply was refering to when Jon suggested a domed piston or milling the head. Both have the effect of reducing the combustion chamber volume so that the compression ratio goes up.
For pump gas here's a general rule of thumb:
Octane: 87 89 91 93
Iron Head CR: 8:1 9:1 10:1 10.5:1
Aluminum CR: 8.5:1 9.5:1 10.5:1 11:1
