# Compression ratios for new Camaro

**URL:** <https://community.cartalk.com/t/compression-ratios-for-new-camaro/24563>\
**Category:** Maintenance/Repairs\
**Tags:** camaro, engines\
**Created:** [January 8, 2009, 12:42am UTC](https://community.cartalk.com/t/compression-ratios-for-new-camaro/24563 "2009-01-08T00:42:25Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Gator26](https://avatars.discourse-cdn.com/v4/letter/g/90db22/32.png) [@Gator26](https://community.cartalk.com/u/Gator26)\
**Post date:** [January 8, 2009, 12:42am UTC](https://community.cartalk.com/t/compression-ratios-for-new-camaro/24563/1 "2009-01-08T00:42:25Z")

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According to GM’s spec sheet, the V6 engine on the new Camaro has a compresstion ratio of 11.3:1 and requires regular gasoline. However, the V8 engine only has a compression ratio of 10.7:1 and requires premium fuel. I thought that the higher compression ratio would require higher octane. What gives?

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**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\
**Post date:** [January 8, 2009, 1:14am UTC](https://community.cartalk.com/t/compression-ratios-for-new-camaro/24563/2 "2009-01-08T01:14:23Z")

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```
There are a number of factors. I would stick with the manufactures recommendations. One likely factor is the lack of or the design limits on the knock sensor and the automatic retard system.
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**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://community.cartalk.com/u/GreasyJack)\
**Post date:** [January 8, 2009, 2:37am UTC](https://community.cartalk.com/t/compression-ratios-for-new-camaro/24563/3 "2009-01-08T02:37:16Z")

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The piece of information the spec sheet is likely omitting is that premium is probably “recommended” with the V6 but, like Joseph was saying, the V6 has the ability to detune itself to run on regular.

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**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\
**Post date:** [January 8, 2009, 2:45am UTC](https://community.cartalk.com/t/compression-ratios-for-new-camaro/24563/4 "2009-01-08T02:45:14Z")

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Here are some of the factors Mr. Meehan’s referring to - # valves (4 valve v6 vs 2 valve v8), combustion chamber geometry (4 valves may allow for a more symetrical design, with the spark plug at the center), piston design, swirl as determined by inlet geometry, computer control of ignition and fuel injection, the list goes on and on.

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**Author:** ![FoDaddy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/fodaddy/32/717_2.png) [@FoDaddy](https://community.cartalk.com/u/FoDaddy)\
**Post date:** [January 8, 2009, 1:30pm UTC](https://community.cartalk.com/t/compression-ratios-for-new-camaro/24563/5 "2009-01-08T13:30:24Z")

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The V6 in the new Camaro uses direct injection. This allows for lower temps in the combustion chamber which eliminates the need for premium fuel. Many modern cars have compression ratios on 10.1:1 or better and don’t require the use of premium fuel. Ain’t technology grand?