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Grady Clay Grady Clay is offline
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Join Date: Dec 2003
Location: Arapahoe County, Colorado, USA
Posts: 9,032
xtrm914,
First, welcome to the Pelican 911 Forum
Even with a 914-6 conversion, you will find a lot of help here.

The first and most basic question is: “What transmission do you want to use?”
If you are willing to use a 915/916 conversion, 930, and later, the sky is the limit for engines.
If you want to use the 914/901/911 transmission, most agree that 2.8 liters is the limit.
Yes, many swear by using 3.0 and 3.2 with the 914 but I won’t.
Your choice with 2.7/2.8, you are at the limit IMHO.
With this stress, an oil pump, filter, cooler extends the transmission life noticeably.

My street hotrod is a ’70 914-6 with a 2.8S, MFI, 11:1 CR and about 1900#, flat sides and still mostly steel.
I use a type 911 side-shift transmission with a ZF LSD and appropriate gears for whatever.
I changed to the big 108 mm CV joints as this has a lot of (potential wheelspin/grab) torque.


I recommend you convert to suitable 911 brakes and 5-bolt hubs.
All the good (mostly 911) suspension is available.


Your proposed 2.7 will be just fine with a 914/901/911 transmission.
There are a lot of subtle mods that will let it live a long and happy life.

I agree, a ‘Mod-S’ or like will be great.
You want to keep your peak hp rpm at or below 7000 - 7300 or so for longevity.
At 10.5:1 CR and twin plugs you will probably be slightly above the limit for pump (93 octane) fuel.
You can make the decision to use race fuel (101-112 octane) as I do but if you do, raise the CR even more.
Above 11:1 is possible and gives stellar performance.
I paid $8/gal last week for 101 octane unleaded for my Max Moritz 3.2 SC.
There is a lot of controversy about fuel and CR but detonation will kill an engine.

It seems like you have a beginning handle on the technical aspects of building a sound 911 engine.
There is a lot of good information available here.
You will find a lot of knowledgeable help.
Be conservative so the engine lasts a good, long time.
Catastrophic failures are unacceptable.

Best,
Grady
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Old 05-04-2011, 05:56 PM
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