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Join Date: Jun 2002
Location: Greenwood, Mississippi
Posts: 94
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Replace short block?
Can I replace my non-turbo 86 block with a 86 turbo block and use my everything else? I have a knock and metal filings around 2 of my camshaft lobes. My son said he was only driving at 72 mph.
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05-16-2004, 05:16 AM
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No. Turbo short block has dished pistons to lower the compression ratio. The N/A doesn't. Also a slight difference in the casting where the head bolts up.
Think there is a special head gasket that will let a turbo engine use an N/A head but since you don't have the rest of the turbo system you would be getting less than 90 HP out of the combination. Maybe just the thing for an aggressive son! If you have problems with the cam then you need to check that the cam gear didn't come loose. There is a 12 point socket head under the dist rotor. A loose cam gear will also cause a knocking sound and the loss of the timing belt due to tracking problems.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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05-16-2004, 09:13 AM
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Join Date: Jul 2001
Location: Edmonton, Alberta, Canada
Posts: 4,530
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SOcal is right you cant use the complete short block because of the compression ratio that is determined by the dished pistons.
Now what is interesting is you could swap your NA pistons and rods and put them into the Turbo block (cranks are the same). You will notice that the turbo cylinders are thicker as well. Everything will bolt straight up for that year. I have seen turbo pistons rods go into NA block and vice versa. No issues either way.......well there are some but none for what you are comtemplating. And if you play your cards right you can sell those turbo pistons and rods and make some of your money back. 
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Alex - PCA Polar Region - Boxster Muncher 86' 944 Turbo - Megasquirt - 326 rwhp/340lbft @ 18 psi SOLD www.edmontonhomelife.com www.edmontonrealestate.ws |
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05-16-2004, 05:48 PM
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Just a side note on rods; the rods in the 83's are forged just like the turbos.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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05-16-2004, 08:20 PM
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Join Date: May 2004
Location: Orlando, FL. Go to school in Tallahassee
Posts: 6
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I'm kind of looking into this, I actually want to have the lower compression. Barring the compression difference, will the N/A head and all other N/A accesories bolt on the the Turbo block? So Cal said something about casting differences, is this true?
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05-26-2004, 12:37 PM
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Join Date: Jun 2002
Location: Greenwood, Mississippi
Posts: 94
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I don't know yet, and this compression thing has me interested - especially since I have read that the 924S engine has more compression but less horsepower at 5500 rpms - so I may end up with a 924S engine in my 1986 944.
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05-26-2004, 01:06 PM
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Why do you want the lower compression?
Also I've heard of the NA head being used on the turbo but with a "special" gasket. Reason was to get a larger exhaust valve and exhaust port with out the ceramic lining. Used for racing. Stan, Stick the 924S engine into the 86 using the 86's fuel rail and lines.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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05-26-2004, 01:15 PM
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1983 Porsche 944 2.5 liter
