2.2E Mild Upgrade. Short stroke or long? Opinions Please!

I just received my very first issue of ESSES today - Ya-hoo! I'm excited to become more involved now that my new toy is nearly ready...
I'm new to the world of the 911 having purchased my first Porsche - a '70E - about a year and a half ago. Since then it's been undergoing a full disassembly/rebuild. The time has come to rebuild the engine. As the engine that came with the car is not a number's matching case but, is a complete 2.2E engine with MFI, I have decided to "upgrade" it a bit.
I'm torn between keeping the short stroke and boring it out to 90mm or change up the crank with a later 70.4mm and change up the pistons to maintain the stock "E" comp. I have an idea of what might be gained/lost with a longer stroke or larger bore so I'm mainly interested to hear what the community thinks of each (advantages/disadvantages), personal experiences or just your 2 cents worth on the matter if so inclined. Either way I go, I'm keeping the MFI. Perhaps some day I'll venture out for track days but for now it's going to be strictly street-only. Any comments or insights would be greatly appreciated.
Thank you in advance. Pictures will follow hopefully very soon. :)

Hi Marc

I too have a 1970 2.2E and a great car they are. I and my good friend Mike Bainbridge rebuilt my engine a couple of years ago. I went for a close to stock rebuild but with 2.2S pistons giving 9.8 : 1 compression ratio and S spec heads. This has given a great engine producing 177HP and 216 NM of torque. It drives really well, a number of other guys have had similar rebuilds and also find the engine great. This also has the benifit that you do not need to do too much with the MFI pump and distributor. A little more info can be found here.

http://www.ddk-online.com/phpBB2/vie...er=asc&start=0

http://i139.photobucket.com/albums/q...y/P1000625.jpg

Kind Regards

Marc - my 2c would be to keep the short stroke configuration. They have a fun revvy character that is not quite the same in the long stoke motors.

Having owned a stock 2.2E in the past and now knowing what the possibilities are I would do a 2.5L SS engine with a non-matching case. That would be a blast.:)

OTOH you can't deny that a 2.7L RS spec wouldn't be a great choice either.

Marc,

I've got a 2.2 modified to a 2.5 short stroke in my 914-6 (for sale!) and it is great fun in any gear. I'm not sure how much hp it makes but it is very strong. I would highly recommend short stroke, regardless of any other mods.

I love my 2.5 ss twin plug. You can click on my 911E link and read about the engine modifications. I am still tuning the mfi after having it rebuilt to match the 2.5

I just upgraded my 71 T to a 2.5 SS. You have almost all fo the elements, well except the PCs. Andial can fix you up with the Mahles. I have a Mod Solex, but your e-cam could give you a very very fun ride.

Hi Curt,
That's a bunch of HP for an engine running with E cams. Are your 2.2 twin plug heads originally from an E or were they upgraded S heads? What kind of compression is your engine giving?

Thanks everyone for your input.
I have conceded that short stroke is my most likely route but a longer stroke motor was a tempting option too (more torque at lower rpm). Here is what I'm thinking. Let me know if I'm leaving anything out that
should be considered..
89-90mm pistons and cylinders. Cam to suit an S spec engine. Rework the MFI system and pump to suit. I'm keeping the case without upgrading to a 7R case (although I've read that this would be a good idea) and having it
worked on in order to accept a the larger cylinders. The stock crank will go back in assuming it all checks out okay. If not, I'll consider a long stroke S crank to replace. This last option would bust my budget slightly
and I'll loose the fun factor worked into the short stroke so I'm trying not to go there.

What about heads? Would the 2.2E head work with a larger domed piston or will I run into issues? If I go with S-type pistons (89-90mm) over a SS crank, won't my compression would drop off the map? I'd like to keep the
compression as close to stock 9.1:1 as possible but I'm unsure if this is possible with the 2.2E heads.

Thanks again for the feedback. It's fun just to explore the various options people have gone with.

Marc-

A couple of things: You mention "Cam to suit an S spec engine." I assume this means an S cam. This will require S ports and an S space cam for your MFI pump. That's a great set up, but $$$$$. Conversely, you've got E cams that might be in great shape (or not). I know that E cams work well with S ports. John knows this too! 177HP from a 2.2 with E cams is nothing to sneeze at. What doesn't work is S cams with E ports. Also, your MFI pump will tolerate significant changes of displacement, but is sensitive to cam changes, so you could consider having the ports done to pep up the top end in conjunction with the displacement increase, be it long or short stroke in the making. E heads and S heads are identical except for the ports, so no worries there with pistons. I'm not sure why you are hesitant about changing the CR, as 9.8:1 is manageable as long as you can use 91 octane fuel and don't get silly with ignition timing. If you are replacing pistons, increasing the CR is pretty much free power. Again, see John's results above.

If you do the 2.5SS, I'd really think about replacing the case. For my motor (2.5SS with E cams, S ports, MFI), I found a late 7R that already had the large cylinder spigots and the factory-executed oil bypass modification. The case also had piston squirters, which my original case, from my '70E, COA verified engine number, did not have. These three features more than paid for the cost of the case, and I have something much stronger as a result. Cases can be found for relatively little.

If your E pistons are OK (and particularly if your crank and rods are not) then I'd think about making a high compression 2.4 with E cams and S ports. Remember that this still results in a 84mm bore and 70.4mm stroke, not exactly a truck motor. It will rev just fine, as any RS or 2.4S owner will tell you. If your crank is great and pistons are shot, then the 2.5 solution is certainly the way to go.

Good work thinking this through. These decisions will stick with you for a long time.

Hi Marc, Yes they are 1969 production 2.2 911s heads twin plugged and cc matched with cleaned up ports. I also had the int sleeved to align the int manifold. I did have the mfi rebuilt to work with the 2.5 ss motor. I collected parts for years so at the time that I did the rebuild all I needed was to do the machining and re assembly. They are Andial supplied 89's for the GTU imsa class 10.3:1. I am running a spacers under the celindors just because I didnt need to rebuild the engine each year.
http://www.early911sregistry.org/for...hmentid=193594