Compression Ratio, help me understand?

S

Screamin' Demon

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Feb 24, 2003

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winchester, va

Dec 11, 2004

#1

• Dec 11, 2004

• #1

Alright as we all know a PI head swap on a 96-98 GT will result in a compression ratio to aprrox. 10:1. My question is, is this reliable and safe on a 90,ooo motor gt, hardly abused at all? Will this increase in compression hurt the motor over time or help it? Let me know guys. No blower will be added in case you are wondering. Thanks

 

GoBabyVroommm

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Mar 22, 2003

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Dec 11, 2004

#2

• Dec 11, 2004

• #2

You'll be fine. Sometimes your compression ratio will change because of the head gaskets your use. The faster you do the PI swap the longer your motor will last. The intake that the 96-98 sucks ballz.

 

tomustang

Psychotic Member

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McLean Hospital

Dec 11, 2004

#3

• Dec 11, 2004

• #3

you're putting new parts on your car, it won't make it worse. if you do the swap just brush off the carbon on the pistons. the compression will rise between 10:1 to 10:5.

 

mrvax

Stay thirsty my friends

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Dec 11, 2004

#4

• Dec 11, 2004

• #4

Just make sure you use the correct grade of fuel to avoid detonation. I also have my timing advanced to 15 degrees BTDC, run 93 octane and never ping.
82,000 and going strong. It's a good engine...change your oil & filter regularly.

 

P

Pitch Black

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Dec 11, 2004

#5

• Dec 11, 2004

• #5

10.1:1 is perfectly safe.....unless you plan to boost

 

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Stanglover96

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Dec 11, 2004

#6

• Dec 11, 2004

• #6

What about with nitrous? Would it be better to get a flip chip and get 2 tunes or what? Also I heard about a bump on the heads that if taken out reduces compression by 1 pt. Is that true?

 

Blev

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Dec 11, 2004

#7

• Dec 11, 2004

• #7

Stanglover96 said:

What about with nitrous? Would it be better to get a flip chip and get 2 tunes or what? Also I heard about a bump on the heads that if taken out reduces compression by 1 pt. Is that true?

Click to expand...

I don't know anything about a "bump" but I know if you remove the swirl dams it lowers the compression.

 

kah9911

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May 20, 2004

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Dec 11, 2004

#8

• Dec 11, 2004

• #8

Well the swirl dams are kind of like bumps. I would not worry to much about a CR of 10. I think they only take out like .5 also, but your fine at 10. Just run higher octaine and you will make a bit more power.

 

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01TrueBlueCobra

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Dec 12, 2004

#9

• Dec 12, 2004

• #9

The only thing different is that you have to run premium gas. Also the Mach 1 is 10.1 compression too. Also make sure you take your short block assembly to a machine shop to have it rebuilt.

 

Gearbanger 101

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Dec 12, 2004

#10

• Dec 12, 2004

• #10

GoBabyVroommm said:

The intake that the 96-98 sucks ballz.

Click to expand...

If you're refering to their flow characteristics, yes, the do in fact "suck ballz" but if it's the fact that their all plastic design makes them prone to cracking, up until 2002 model year, PI intakes were all plasic as well. You gotta specify the intake with the aluminum crossover if that's the case.

Blev said:

I don't know anything about a "bump" but I know if you remove the swirl dams it lowers the compression.

Click to expand...

Which also makes it brutal on gas. I wouldn't knock em off if I were him.

 

P

Pitch Black

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#11

• Dec 12, 2004

• #11

Stanglover96 said:

What about with nitrous? Would it be better to get a flip chip and get 2 tunes or what? Also I heard about a bump on the heads that if taken out reduces compression by 1 pt. Is that true?

Click to expand...

Nitrous is safe as well. You have to realize that there are many cars out there running a 10.1 CR. Mach 1's, LS1's, etc., all run 10.1:1 CR stock. There are THOUSANDS of LS1's running nitrous without any problem. You don't need to worry about your CR until you boost the engine.

 

S

Screamin' Demon

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Feb 24, 2003

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winchester, va

Dec 12, 2004

#12

• Dec 12, 2004

• #12

Well I already have my timing advanced through my chip and I run premium right now currently. Cant wait to have these heads and cams.