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ManFromNapa
Samba Member
Joined: March 08, 2012
Posts: 184
Location: United States
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 Posted: Mon May 03, 2021 3:55 pm Post subject: Compression Ratio for a 2231 Cam |
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Hey people. I'm building a 1600 for a daily driver. Using a 2231 cam for better MPG. Not looking to be super fast.
According to the AirCooled.net site, they recommend staying below an 8.5:1 compression ratio. I know higher compression ratio improves HP & efficiency, but it also produces more heat. What CR would most guys recommend? I had one builder tell me to stay down around 8.1, another tell me to get as much as I can out of it.
Again, this is a daily driver. Looking for longer life, and reliability.
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North Bay Air Cooled - VW Club in Napa, CA
http://www.northbayaircooled.com/
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FreeBug
Samba Member
Joined: March 12, 2012
Posts: 4278
Location: deepest, darkest Switzerland
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| Posted: Mon May 03, 2021 4:05 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| Hi, you'll need to specify the fuel you intend to use. |
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ManFromNapa
Samba Member
Joined: March 08, 2012
Posts: 184
Location: United States
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| Posted: Mon May 03, 2021 4:13 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| FreeBug wrote: |
| Hi, you'll need to specify the fuel you intend to use. |
Regular 87 Octane.
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North Bay Air Cooled - VW Club in Napa, CA
http://www.northbayaircooled.com/
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mark tucker
Samba Member
Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Mon May 03, 2021 4:52 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| what ever cr you choose try to keep the deck around .040"(1 mm) I wont build any thing low cr like that.but thats me. |
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Teeroy 
Samba Member
Joined: April 20, 2003
Posts: 3685
Location: Eastern WA
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| Posted: Mon May 03, 2021 5:36 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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John puts those recomendations on the site for a reason, thats where they are designed to work best. Unless you live at a very high elevation or are gonna run a high octane fuel, set it were he says the specific cam recommends
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bugguy1967
Samba Member
Joined: January 16, 2008
Posts: 4341
Location: Los Angeles, CA 90016
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| Posted: Mon May 03, 2021 7:10 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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Let's see the cam card!
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine" |
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jpaull
Samba Member
Joined: February 22, 2005
Posts: 3462
Location: Paradise, Ca
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| Posted: Mon May 03, 2021 7:33 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| bugguy1967 wrote: |
| Let's see the cam card! |
The first relevant question that will lead to a relevant answer💪💪  |
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[email protected]
Samba Member
Joined: May 17, 2003
Posts: 4863
Location: Harmony, PA
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| Posted: Mon May 03, 2021 7:36 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| bugguy1967 wrote: |
| Let's see the cam card! |
I’m going to say intake closes around 41 degrees ABDC..... |
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ManFromNapa
Samba Member
Joined: March 08, 2012
Posts: 184
Location: United States
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| Posted: Mon May 03, 2021 8:53 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| bugguy1967 wrote: |
| Let's see the cam card! |
I just ordered the cam today, so I don't have the card yet. Was hoping someone else might. I appreciate everyone's comments.
_________________
North Bay Air Cooled - VW Club in Napa, CA
http://www.northbayaircooled.com/
Check out my band, Thru The Haze
http://www.thruthehazeband.com/ |
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ManFromNapa
Samba Member
Joined: March 08, 2012
Posts: 184
Location: United States
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| Posted: Mon May 03, 2021 8:59 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| Teeroy wrote: |
| John puts those recomendations on the site for a reason, thats where they are designed to work best. Unless you live at a very high elevation or are gonna run a high octane fuel, set it were he says the specific cam recommends |
John is great and has always given me good advice. To be clear, his site says
"Use a compression ratio no higher than 8.5:1", but to me that's not a recommendation to have 8.5:1. Just not to go higher.
_________________
North Bay Air Cooled - VW Club in Napa, CA
http://www.northbayaircooled.com/
Check out my band, Thru The Haze
http://www.thruthehazeband.com/ |
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Alstrup
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Joined: July 12, 2007
Posts: 7214
Location: Videbaek Denmark
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vwracerdave
Samba Member
Joined: November 11, 2004
Posts: 15303
Location: Deep in the 405
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| Posted: Tue May 04, 2021 7:12 am Post subject: Re: Compression Ratio for a 2231 Cam |
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1600 daily driver on 87 pump gas. 7.7-8.0 with the stock carb. 7.9-8.2 with dual carbs.
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Ohio Tom
Samba Member
Joined: February 09, 2006
Posts: 1660
Location: Marshallville Ohio
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| Posted: Tue May 04, 2021 7:41 am Post subject: Re: Compression Ratio for a 2231 Cam |
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8,0 would be the highest I would recommend.
Stay in the 7's for stock and near stock stuff.
Higher will only increase the fuel octane requirements and add heat.
Both will kill a motor.
You want it to last, right?
BTW premium fuel is $.95 more expensive a gallon than regular. |
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ManFromNapa
Samba Member
Joined: March 08, 2012
Posts: 184
Location: United States
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| Posted: Tue May 04, 2021 2:48 pm Post subject: Re: Compression Ratio for a 2231 Cam |
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| Ohio Tom wrote: |
BTW premium fuel is $.95 more expensive a gallon than regular. |
I agree.. but I'm building this for a friend who I know will use 87. I'll try to stick to around 8.0:1
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North Bay Air Cooled - VW Club in Napa, CA
http://www.northbayaircooled.com/
Check out my band, Thru The Haze
http://www.thruthehazeband.com/ |
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