rebuild options
07-18-2012, 08:54 PM
#18
Drifting
3.6 from LA dismantlers - 77K miles from a tiptronic cabriolet.
90 day "warranty"
Got it and fixed some oil leaks - having some issues at the start - would not idle - would not start sometimes. turns out had zero compression on #3 = 50 on #6 - need valve guides - piston to cylinder was getting blow by - turns out the bearings were on their last legs -
That said - I'd rather rebuild a 3.6 than a 3.2 - 3.6 has dual plugs - better oil fed tenioners, knock sensors - etc.
90 day "warranty"
Got it and fixed some oil leaks - having some issues at the start - would not idle - would not start sometimes. turns out had zero compression on #3 = 50 on #6 - need valve guides - piston to cylinder was getting blow by - turns out the bearings were on their last legs -
That said - I'd rather rebuild a 3.6 than a 3.2 - 3.6 has dual plugs - better oil fed tenioners, knock sensors - etc.
07-19-2012, 12:59 AM
#19
3.6 from LA dismantlers - 77K miles from a tiptronic cabriolet.
90 day "warranty"
Got it and fixed some oil leaks - having some issues at the start - would not idle - would not start sometimes. turns out had zero compression on #3 = 50 on #6 - need valve guides - piston to cylinder was getting blow by - turns out the bearings were on their last legs -
That said - I'd rather rebuild a 3.6 than a 3.2 - 3.6 has dual plugs - better oil fed tenioners, knock sensors - etc.
90 day "warranty"
Got it and fixed some oil leaks - having some issues at the start - would not idle - would not start sometimes. turns out had zero compression on #3 = 50 on #6 - need valve guides - piston to cylinder was getting blow by - turns out the bearings were on their last legs -
That said - I'd rather rebuild a 3.6 than a 3.2 - 3.6 has dual plugs - better oil fed tenioners, knock sensors - etc.
07-26-2012, 11:20 PM
#21
Track Day
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I had a trip to the west coast this week, which gave me a lot of airplane time to read Wayne's rebuild book and the "911 Performance Handbook". I think they're both great. There is definitely some overlap, but different examples and different perspectives are helpful. I'd say they are largely in agreement.
It seems that the two most attractive options are a 3.4L or 3.5L rebuild of my current 3.2 factory original. Wayne describes the former as “bolt-on” and the latter as “one of the best normally aspirated engines you can build” and capable of “325-350hp”. With 180k on my engine, I’m expecting lots of things to be worn out, so new pistons and cylinders are probably a must anyway, so I might as well go bigger. So, I'm narrowing down my thinking on the general direction (rebuilding my engine, not doing a swap), but now I have more and more questions.
A lot of these questions are dependent on one another, so I'll try to consider in a logical sequence.
Compression ratio and octane:
I want to be able to run regular ole pump gas. In North Carolina, that means 93 octane for premium unleaded ((RON+MON)/2 method) . There doesn't appear to be any black and white line on compression ratio that I should not cross to maintain that goal. Assuming I go with a double plug option, I think the "line" is somewhere between 10:1 and 11:1. Anyone have an opinion about where that boundary is for an otherwise typical engine? On the other hand, it seems as if you can go even higher if....
Fuel/Ignition/Engine Management:
Wayne implies that you can get away with really high compression if you have the right EMS, specifically "a super high 12:1 compression engine that runs on pump gas". Anyone have any experience or thoughts at that frontier? Does it require extensive tuning and expertise to get it just right? Is such a high compression beast of an engine inherently short-lived?
Chip v. EMS:
My '85 has the Motronic system that can be chipped. I have read a lot of people who get their chips custom made by Steve Wong. To simplify, it seems that getting a custom chip is like a one time programming of an EMS. Having an EMS means you can experiment and re-program any time you like. If you're only going to program it once to match the engine as built, you don't need a reprogrammable system. Is that a fair description of the situation? Of course, that ignores the difference in coil packs v. traditional coil, distributor, etc in terms of spark duration and intensity at high RPM. Also, an EMS costs money in some ways, but I think saves money in others, in that I wouldn’t have to find a 964 double distributor.
EMS v. traditional equipment:
I have a really stupid question. With an advanced EMS (say TEC3 with coil packs), do I still need a distributor cap at all? If not, how is the timing managed?
EFI v. carburetor:
I put a Weber on my MGB about 30 years ago, and that was a great improvement. However, at this point, I think I like the idea of electronic control. I’m an analytical, quantitative, software kind of thinker. Carbs seem like they are as much art and black magic as they are science, and therefore they don’t play to my strengths. Am I missing something?
Pistons
Thanks Packet for the link to JE pistons. They seem to have a wide selection. Does anyone have a recommended site for the Mahle pistons. I can get general descriptions and links, but haven’t found a site where I can look up the actual pistons and pricing for the Porsche P&E. Any suggestions? Also, I would love to hear any ones thoughts on the relative merit/ quality of JE, Mahle, or other manufacturers.
Compression ratio calculation:
I have been surprised in the literature and in Ed’s post that measuring your own exact compression ratio seems to be a necessary step. Is it critical? Does that mean I need to buy 2+ gasket sets because I’m going to have to at least partially assemble the block once (or more) just to measure it, and then again for the final assembly?
I think that’s all I can consider at this point. Exhaust and cam questions will undoubtedly follow at some point.
Thanks everyone for your input so far. I think this is a great community.
It seems that the two most attractive options are a 3.4L or 3.5L rebuild of my current 3.2 factory original. Wayne describes the former as “bolt-on” and the latter as “one of the best normally aspirated engines you can build” and capable of “325-350hp”. With 180k on my engine, I’m expecting lots of things to be worn out, so new pistons and cylinders are probably a must anyway, so I might as well go bigger. So, I'm narrowing down my thinking on the general direction (rebuilding my engine, not doing a swap), but now I have more and more questions.
A lot of these questions are dependent on one another, so I'll try to consider in a logical sequence.
Compression ratio and octane:
I want to be able to run regular ole pump gas. In North Carolina, that means 93 octane for premium unleaded ((RON+MON)/2 method) . There doesn't appear to be any black and white line on compression ratio that I should not cross to maintain that goal. Assuming I go with a double plug option, I think the "line" is somewhere between 10:1 and 11:1. Anyone have an opinion about where that boundary is for an otherwise typical engine? On the other hand, it seems as if you can go even higher if....
Fuel/Ignition/Engine Management:
Wayne implies that you can get away with really high compression if you have the right EMS, specifically "a super high 12:1 compression engine that runs on pump gas". Anyone have any experience or thoughts at that frontier? Does it require extensive tuning and expertise to get it just right? Is such a high compression beast of an engine inherently short-lived?
Chip v. EMS:
My '85 has the Motronic system that can be chipped. I have read a lot of people who get their chips custom made by Steve Wong. To simplify, it seems that getting a custom chip is like a one time programming of an EMS. Having an EMS means you can experiment and re-program any time you like. If you're only going to program it once to match the engine as built, you don't need a reprogrammable system. Is that a fair description of the situation? Of course, that ignores the difference in coil packs v. traditional coil, distributor, etc in terms of spark duration and intensity at high RPM. Also, an EMS costs money in some ways, but I think saves money in others, in that I wouldn’t have to find a 964 double distributor.
EMS v. traditional equipment:
I have a really stupid question. With an advanced EMS (say TEC3 with coil packs), do I still need a distributor cap at all? If not, how is the timing managed?
EFI v. carburetor:
I put a Weber on my MGB about 30 years ago, and that was a great improvement. However, at this point, I think I like the idea of electronic control. I’m an analytical, quantitative, software kind of thinker. Carbs seem like they are as much art and black magic as they are science, and therefore they don’t play to my strengths. Am I missing something?
Pistons
Thanks Packet for the link to JE pistons. They seem to have a wide selection. Does anyone have a recommended site for the Mahle pistons. I can get general descriptions and links, but haven’t found a site where I can look up the actual pistons and pricing for the Porsche P&E. Any suggestions? Also, I would love to hear any ones thoughts on the relative merit/ quality of JE, Mahle, or other manufacturers.
Compression ratio calculation:
I have been surprised in the literature and in Ed’s post that measuring your own exact compression ratio seems to be a necessary step. Is it critical? Does that mean I need to buy 2+ gasket sets because I’m going to have to at least partially assemble the block once (or more) just to measure it, and then again for the final assembly?
I think that’s all I can consider at this point. Exhaust and cam questions will undoubtedly follow at some point.
Thanks everyone for your input so far. I think this is a great community.
07-27-2012, 01:16 PM
#22
Rennlist Member
From my personal standpoint:
Mahles are the way to go for longevity
If you go to an EFI system, you had better know what you are doing web tuning, especially when playing at the higher compression ratio. A mistake will be costly.
I preferred a DME with a chip set to my parameters.
I think that unless you NEED every bit of HP you can get out of the motor, you are better staying at somewhere around 10.5:1 or so and concentrate on being bulletproof. You get nice HP, and durability. Beyond that, you have diminishing returns, and you'll be to where you will way to tear the motor down regularly for R&R. Cost escalates quickly at that point.
Mahles are the way to go for longevity
If you go to an EFI system, you had better know what you are doing web tuning, especially when playing at the higher compression ratio. A mistake will be costly.
I preferred a DME with a chip set to my parameters.
I think that unless you NEED every bit of HP you can get out of the motor, you are better staying at somewhere around 10.5:1 or so and concentrate on being bulletproof. You get nice HP, and durability. Beyond that, you have diminishing returns, and you'll be to where you will way to tear the motor down regularly for R&R. Cost escalates quickly at that point.
07-28-2012, 01:49 PM
#24
Bill,
This is a great thread! I'm certainly interest in following your project. You asked about builders. There are a couple in this area that you may already be familiar with as well as a few in the Western part of the state and in the Charlotte area.
Good luck,
Gary
This is a great thread! I'm certainly interest in following your project. You asked about builders. There are a couple in this area that you may already be familiar with as well as a few in the Western part of the state and in the Charlotte area.
Good luck,
Gary
01-24-2013, 12:49 AM
#25
Track Day
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Well, after a long break and getting other things taken care of, I'm finally getting started on the project. I got the engine out and on a stand this past weekend. Removed the fuel injection unit as a whole tonight.
Here's what I'm thinking on the build.
- Use my original cylinders, but re-bore and plate to a 98mm ,giving me 3.4 L. Anybody have experience or knowledge about re-boring older cylinders?
- Use JE pistons set up for 10.5 CR
- twin plug configuration
- leaning towards Tec3 or similar for fuel and ignition management. Given how much i'd spend on a double distributor, a new chip and replacing the brittle connections that shattered when I touched them, it seems like I can get an up to date, very flexible and more capable system for nearly the same price. I'm not totally sure about this, still researching.
- Not sure about the cam yet. Researching
I'd welcome any thoughts.
Here's what I'm thinking on the build.
- Use my original cylinders, but re-bore and plate to a 98mm ,giving me 3.4 L. Anybody have experience or knowledge about re-boring older cylinders?
- Use JE pistons set up for 10.5 CR
- twin plug configuration
- leaning towards Tec3 or similar for fuel and ignition management. Given how much i'd spend on a double distributor, a new chip and replacing the brittle connections that shattered when I touched them, it seems like I can get an up to date, very flexible and more capable system for nearly the same price. I'm not totally sure about this, still researching.
- Not sure about the cam yet. Researching
I'd welcome any thoughts.
01-24-2013, 01:01 AM
#26
Rennlist Member
What kind of knowledge do you have about tuning? Going to an engine management system will require that.I went with the Andial splitter and 964 dist, and it was very straight forward, along with a Steve Wong chip.
Fixing wiring problems may be simpler in the long run.
I used the DC-19 cam from Dougherty Racing Cams.
Fixing wiring problems may be simpler in the long run.
I used the DC-19 cam from Dougherty Racing Cams.
Well, after a long break and getting other things taken care of, I'm finally getting started on the project. I got the engine out and on a stand this past weekend. Removed the fuel injection unit as a whole tonight.
Here's what I'm thinking on the build.
- Use my original cylinders, but re-bore and plate to a 98mm ,giving me 3.4 L. Anybody have experience or knowledge about re-boring older cylinders?
- Use JE pistons set up for 10.5 CR
- twin plug configuration
- leaning towards Tec3 or similar for fuel and ignition management. Given how much i'd spend on a double distributor, a new chip and replacing the brittle connections that shattered when I touched them, it seems like I can get an up to date, very flexible and more capable system for nearly the same price. I'm not totally sure about this, still researching.
- Not sure about the cam yet. Researching
I'd welcome any thoughts.
Here's what I'm thinking on the build.
- Use my original cylinders, but re-bore and plate to a 98mm ,giving me 3.4 L. Anybody have experience or knowledge about re-boring older cylinders?
- Use JE pistons set up for 10.5 CR
- twin plug configuration
- leaning towards Tec3 or similar for fuel and ignition management. Given how much i'd spend on a double distributor, a new chip and replacing the brittle connections that shattered when I touched them, it seems like I can get an up to date, very flexible and more capable system for nearly the same price. I'm not totally sure about this, still researching.
- Not sure about the cam yet. Researching
I'd welcome any thoughts.
01-27-2013, 02:52 PM
#29
Rennlist Member
^^^Total cost to you means nothing without full details of the build. Secondly, it looks to have happened in 2000, parts cost has changed dramatically since then.
01-27-2013, 03:20 PM
#30
Rennlist Member
And total cost means nothing without knowing who actually considered the parameters of the build, as well as performing the actual labor. I'll guess the proportion of modified 911 engines rebuilt that end up being less than the sum of their parts are 50:1? More?
Get a kick out of the post somewhere previous claiming 325-350HP out of a 3.4/3.5 street build.
And continually amazed at the DIY gravitation toward the aftermarket pistons fitted to original cylinders.
Get a kick out of the post somewhere previous claiming 325-350HP out of a 3.4/3.5 street build.
And continually amazed at the DIY gravitation toward the aftermarket pistons fitted to original cylinders.
