2.7 CIS engine upgrade - opinions
05-10-2002, 04:03 AM
#1
Instructor
Thread Starter
2.7 CIS engine upgrade - opinions
I am sure this topic has been beaten to death and I have read BA's performance handbook back to back. Still I would like to get some feedback for an engine upgrade either using the current 2.7CIS stock engine or going to a 3.0 or 3.2 Carrera engine.
The current engine is a 1974 911 CIS bone stock with the narrow ports (no S or T) but no EGR crap
It is running fine with 140k miles after a professional rebuilt at 95k miles. It has the good Mahle parts. It does start to use some oil though. Probably good for another 20k – 30k miles before it needs to come apart.
First, when I use the 2.7 stock engine would you go with the Weber carb/Cam upgrade or with the high compression pistons/cylinders? What is the expected performance and the associated costs?
What are going prices for 3.0 or 3.2 Carrera engines in good condition in SoCal? Where would you buy? How much work is it to implant those into a 1974 with 915 tranny?
Any feedback and or conversion stories are welcome.
Ingo
The current engine is a 1974 911 CIS bone stock with the narrow ports (no S or T) but no EGR crap
It is running fine with 140k miles after a professional rebuilt at 95k miles. It has the good Mahle parts. It does start to use some oil though. Probably good for another 20k – 30k miles before it needs to come apart.First, when I use the 2.7 stock engine would you go with the Weber carb/Cam upgrade or with the high compression pistons/cylinders? What is the expected performance and the associated costs?
What are going prices for 3.0 or 3.2 Carrera engines in good condition in SoCal? Where would you buy? How much work is it to implant those into a 1974 with 915 tranny?
Any feedback and or conversion stories are welcome.
Ingo
05-10-2002, 01:46 PM
#2
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At the last POC event my buddy over revved his 2.7 and now it requires a re-build of course. The re-build was quoted at $4k, a 3.0 motor at $4k, and a 3.2 at $4500.
It seems the best choice for him is to buy a replacement motor to get up and running, and re-build the 2.7 himself and sell it at a later date.
Implanting the 3.0 into your car is rather easy even with CIS. The 3.2 is easy as well if you go with carbs, but the DME unit and stock injection will be a little more work to modify the 915 housing to accept the sensors at the flywheel.
If you rebuild your motor and retain the CIS, I have heard that wild cams cause the CIS pulsate and you would realize no gain in performance. I would consider MFI, cams and higher CR pistons for a nice power gain and you wouldn't have to mortgage the house to do it.
Anyway, just my unbiased opinion.
BTW, avoid MM for rebuilds (we all know who they are )
Good luck !
It seems the best choice for him is to buy a replacement motor to get up and running, and re-build the 2.7 himself and sell it at a later date.
Implanting the 3.0 into your car is rather easy even with CIS. The 3.2 is easy as well if you go with carbs, but the DME unit and stock injection will be a little more work to modify the 915 housing to accept the sensors at the flywheel.
If you rebuild your motor and retain the CIS, I have heard that wild cams cause the CIS pulsate and you would realize no gain in performance. I would consider MFI, cams and higher CR pistons for a nice power gain and you wouldn't have to mortgage the house to do it.
Anyway, just my unbiased opinion.
BTW, avoid MM for rebuilds (we all know who they are )
Good luck !
05-12-2002, 08:24 PM
#3
The only issues with a 3.2/3.6 with DME and an earlier 915 is first the fly wheel which must have the DME teeeth on its circumference, these are readily available from a number of sources including Patrick Motorsports
<a href="http://www.patrickmotorsports.com/" target="_blank">Patrick Motorsports</a>
and second the transmission mod which can easily be done with a scroll saw, here is a pic of my mg case 915 modified for a 3.6 at area A
Unless building to a class or subject to stringent emission regs I would highly recommend the extra torque available from any of the larger engines, not to mention their reliability.
<a href="http://www.patrickmotorsports.com/" target="_blank">Patrick Motorsports</a>
and second the transmission mod which can easily be done with a scroll saw, here is a pic of my mg case 915 modified for a 3.6 at area A
Unless building to a class or subject to stringent emission regs I would highly recommend the extra torque available from any of the larger engines, not to mention their reliability.
05-14-2002, 06:33 PM
#4
Instructor
Thread Starter
[quote]Originally posted by Howard:
<strong> a 3.0 motor at $4k, and a 3.2 at $4500.
</strong><hr></blockquote>
That's sounds reasonable if not on the low end. Especially for the 3.2. What are reliable sources for 3.2's IYHO?
I am thinking of going with the 3.2 option and rebuilt my 2.7 slowly as a fun project with no rush.
<strong> a 3.0 motor at $4k, and a 3.2 at $4500.
</strong><hr></blockquote>
That's sounds reasonable if not on the low end. Especially for the 3.2. What are reliable sources for 3.2's IYHO?
I am thinking of going with the 3.2 option and rebuilt my 2.7 slowly as a fun project with no rush.
05-14-2002, 06:40 PM
#5
Instructor
Thread Starter
[quote]Originally posted by Bill Verburg:
<strong>The only issues with a 3.2/3.6 with DME and an earlier 915 is first the fly wheel which must have the DME teeeth on its circumference, these are readily available from a number of sources including Patrick Motorsports and second the transmission mod which can easily be done with a scroll saw, here is a pic of my mg case 915 modified for a 3.6 at area A
Unless building to a class or subject to stringent emission regs I would highly recommend the extra torque available from any of the larger engines, not to mention their reliability.</strong><hr></blockquote>
Bill I remember I have seen a nice project with tons of pictures for a 3.6 conversion a while ago. Pretty sure it was a red car. Can't seem to find that link anymore, though.
It looked pretty complicated there and the guy had a lot of work done to make everything fit. I think he had to buy the conversion kit for $1500 plus the engine plus all the work. Does that sound familiar?
However, how much power will the 915 handle before it budges?
What are the differences between the 3.2 and the 3.6 conversions if any from your knowledge?
Ingo
<strong>The only issues with a 3.2/3.6 with DME and an earlier 915 is first the fly wheel which must have the DME teeeth on its circumference, these are readily available from a number of sources including Patrick Motorsports and second the transmission mod which can easily be done with a scroll saw, here is a pic of my mg case 915 modified for a 3.6 at area A
Unless building to a class or subject to stringent emission regs I would highly recommend the extra torque available from any of the larger engines, not to mention their reliability.</strong><hr></blockquote>
Bill I remember I have seen a nice project with tons of pictures for a 3.6 conversion a while ago. Pretty sure it was a red car. Can't seem to find that link anymore, though.
It looked pretty complicated there and the guy had a lot of work done to make everything fit. I think he had to buy the conversion kit for $1500 plus the engine plus all the work. Does that sound familiar?
However, how much power will the 915 handle before it budges?
What are the differences between the 3.2 and the 3.6 conversions if any from your knowledge?
Ingo
05-14-2002, 11:13 PM
#6
Did you look at my 3.6 transplant page?
<a href="http://www.pelicanparts.com/MotorCity/wmv/3_6liter.htm" target="_blank">3.6 transplant</a>
The red car was probably Thom Fitzpatrick, Jim Williams has a white one, Jack Olsen's is black, all have links on my page, all provide a fair amout of detail of the work involved in this sort of swap. In addition Patrick Motorsports and Dr Steve Timmins are commercial vendors with good info(their links are also on that page). In the Northwest Steve Weiner has done some magnificant swaps of his own. I don't know if he generally does this type of work though
<a href="http://www.easystreet.com/~porsche/" target="_blank">Rennsport Systems</a>
As outlined in my previous post the older 915s will need a bit of metal removed for the DME sensor to read the crankshaft position from the fly wheel teeth. This is the only mod required of the trans itself(the sensor bolts to the engine, the Patrick flywheel uses the stock 225mm 915 clutch/pp and bolts directly to the 964/993 crankshaft as pictured
Before I did the swap I asked every one I could the same question about the durability of the 915 in this application, These included well known factory developmental and racing engineers and mechanics from various factory race teams, all universally agreed that there would be few if any durability probems witha relatively stock 3.6(up to ~300-320hp). In general reliability would go up with the newer al case 915s and be best with a cooler. I used my mg case 915 with zero problems for 8 yrs behind my '93 964 engine. It was only swapped out recently to get a lsd, and different, therefore better for me, gearing, the cooler was a side benefit, not necessary but nice.
Other items such as heat, exhaust, oil coolers, electrical connections, sheet metal are a bit more involved but really no big deal.
<a href="http://www.pelicanparts.com/MotorCity/wmv/3_6liter.htm" target="_blank">3.6 transplant</a>
The red car was probably Thom Fitzpatrick, Jim Williams has a white one, Jack Olsen's is black, all have links on my page, all provide a fair amout of detail of the work involved in this sort of swap. In addition Patrick Motorsports and Dr Steve Timmins are commercial vendors with good info(their links are also on that page). In the Northwest Steve Weiner has done some magnificant swaps of his own. I don't know if he generally does this type of work though
<a href="http://www.easystreet.com/~porsche/" target="_blank">Rennsport Systems</a>
As outlined in my previous post the older 915s will need a bit of metal removed for the DME sensor to read the crankshaft position from the fly wheel teeth. This is the only mod required of the trans itself(the sensor bolts to the engine, the Patrick flywheel uses the stock 225mm 915 clutch/pp and bolts directly to the 964/993 crankshaft as pictured
Before I did the swap I asked every one I could the same question about the durability of the 915 in this application, These included well known factory developmental and racing engineers and mechanics from various factory race teams, all universally agreed that there would be few if any durability probems witha relatively stock 3.6(up to ~300-320hp). In general reliability would go up with the newer al case 915s and be best with a cooler. I used my mg case 915 with zero problems for 8 yrs behind my '93 964 engine. It was only swapped out recently to get a lsd, and different, therefore better for me, gearing, the cooler was a side benefit, not necessary but nice.
Other items such as heat, exhaust, oil coolers, electrical connections, sheet metal are a bit more involved but really no big deal.
05-16-2002, 02:30 PM
#7
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[quote]Originally posted by Howard:
<strong>...I would consider MFI, cams and higher CR pistons for a nice power gain and you wouldn't have to mortgage the house to do it. </strong><hr></blockquote>
Actually Howard, I think you would need to mortgage the house to go the MFI route.
-Chris
<strong>...I would consider MFI, cams and higher CR pistons for a nice power gain and you wouldn't have to mortgage the house to do it. </strong><hr></blockquote>
Actually Howard, I think you would need to mortgage the house to go the MFI route.
-Chris
