2.7 Six conversion questions, Oil cooler and motronic |
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2.7 Six conversion questions, Oil cooler and motronic |
bigkensteele |
Feb 26 2015, 10:19 PM
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#1
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Major Member Group: Members Posts: 2,197 Joined: 30-August 04 From: Cincinnati, OH Member No.: 2,660 Region Association: South East States |
Topic 1: Has anyone ever tried mounting an oil cooler under a GT lid just above the fan, and if so does it keep the temp low enough for DE events?
Topic 2: Has anyone here ever adapted motronic from a 3.2 to work on a 2.7? If so, what is involved? Which distributor? What cam? Stock low compression CIS pistons or JEs? Topic 3: What kind of power can I get if I keep the CIS but am willing to port the heads, change cams and go to JE pistons? Please feel free to address any or all of the above? I have a '74 2.7 core that is currently torn apart and ready to send out for machining. It already has case-savers and nikasil jugs, so I am going to stay at 2.7. I have all of the CIS parts, so that is an option for induction, but I would rather do something else (other than carbs). I will also be running stock 6 heat exchangers and a 911 muffler. I just can't bear the thought of rebuilding this thing and only ending up with 150 hp, so any tips would be most appreciated. |
Steve |
Feb 27 2015, 01:46 PM
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#2
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914 Guru Group: Members Posts: 5,587 Joined: 14-June 03 From: Orange County, CA Member No.: 822 Region Association: Southern California |
A 2.7 runs a lot hotter than an aluminum 3.0 or 3.2. I would go with a front cooler or under the rear trunk with a fan and grill to protect the cooler from rocks.
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bigkensteele |
Feb 27 2015, 10:40 PM
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#3
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Major Member Group: Members Posts: 2,197 Joined: 30-August 04 From: Cincinnati, OH Member No.: 2,660 Region Association: South East States |
A 2.7 runs a lot hotter than an aluminum 3.0 or 3.2. I would go with a front cooler or under the rear trunk with a fan and grill to protect the cooler from rocks. I will not (nor could I) run the thermo reactors used on the 75 - 76 911 motors. The core that I have is a 74 with an 11 blade fan. I will be running either headers or six exhchangers. I am not a metallurgist, but I cannot fathom how the single variable of case material (mag. vs. alum.) could account for any significant increase in thermo-retention, especially when compared to a larger displacement motor. Not trying to be contentious, but I need to understand how an otherwise equal engine would run hot just because it was a mag. case 2.7 vs. a alum. case 3.0 or 3.2. Thanks to all for the input. |
gereed75 |
Feb 27 2015, 11:18 PM
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#4
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Senior Member Group: Members Posts: 1,246 Joined: 19-March 13 From: Pittsburgh PA Member No.: 15,674 Region Association: North East States |
QUOTE I am not a metallurgist, but I cannot fathom how the single variable of case material (mag. vs. alum.) could account for any significant increase in thermo-retention, especially when compared to a larger displacement motor. Not trying to be contentious, but I need to understand how an otherwise equal engine would run hot just because it was a mag. case 2.7 vs. a alum. case 3.0 or 3.2. (IMG:style_emoticons/default/agree.gif) Not an experienced expert in 911's, but thermodynamics is thermodynamics. The heat generated to make say 180 hp will basically be same no matter what the engine is made of. The difference in heat carried away by either mag or AL cases would not be significant. Timing can make a huge difference in the amount of heat generated by aircooled motors. More advance generates higher peak combustion pressures and can actually produce less HP. If your motor runs hot in a system that otherwise should provide adequate cooling, back off the timing a bit. I suspect the "2.7's run hot" belief comes from the era when Porsche tried the thermal reactors to meet emissions. BigKen, I suggest you burn some midnight oil on the Pelican 911 rebuild board. There is much to learn there. |
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