2.2T engine rebuild to 2.4 Specs - need help
 

:confused:

I have a 72 911T that had its engine replaced by a previous owner with a 2.2T with Webers. It burns oil and doesn't have the best mileage. I'd like to return it closer to its 2.4 heritage and otherwise clean it up using the 2.2 as a core. It's a daily driver and I am otherwise perfectly happy with its performance.

I've read Wayne's option for a 2.2 to 2.5 upgrade and a ton of threads on the subject but most deal with racing engines or very significant performance upgrades that may/may not apply to my situation. I's like to keep it fairly simple both for $$$$ reasons and so as not to overreach my modest mechanical aptitude and screw it up.

Here's my preliminary plan. Please critique. Thanks much for your help.

Case 2.2 as is
Crank 2.4/2/7
Rods 2.4/2/7
P&C's new 2.4T's ( Are there refurbish options for my existing 2.2's?)
Cams & towers 2.2T as is
Heads 2.2T as is
fuel webers as is w/ new jets, etc.
distributor 2.2 as is sent out for recurving?

I'm assuming when done, the cams, points, ignition timing, etc. would all be set to 2.4T specs?

Thanks again for you help!!

I'll be embarking on the same journey, hopefully soon. I thought about upgrading my 2.2 to a 2.4 but I think I'm going to go in a different direction. I see why you would want to return your engine to it's original displacement of 2.4, however. Your plan is looking okay to me. Others with more experience will be in here to comment soon. I don't know if you're not mentioning it or your not taking it into consideration yet, but you really need to consider doing the machine work to the case. The mag cases warp across planes and dimensions and even though they may measure in spec, it would be wise to get the machine work done. At least case savers all over line bore and resurface to standard, maybe shuffle pin, head work of course. Maybe you can use your cylinders if they are biral if not you can probably find a usable set. Your pistons are probably paper weights by now as the ring gaps are probably out of spec and if you want a hotter cam, you want to find some appropriate E or S pistons. Webers are great. I just purchased some myself. If those need refurbishment, you might want to talk to Paul at Performance Oriented, his knowledge on these carbs is pretty impressive.
Good luck.

2,2 to 2.4 specs
 

Thanks for the info. I wasn't aware that case macining is almost always required (approx price). Even though I didn't include machining, I know some will be required. I don't have the engine out or disassembled yet so this is hypotetical at this point. I will definitely include timecerts if they're not already there.

2.4T pistons give the lowest compression ratio of all the 2.2 or 2.4 pistons. If you are buying pisons anyway, I would go for a 2.2E set. They will give around 9:1.

You have to measure your pistons and cylinders to see if they are still in spec. If so, 2.2T pistons will give about 8.5:1 compression ratio with 2.4 crank and rods. Which is about equal to a 2.4S.

2.2 to 2.4
 

I was thinking of 2.2E pistons as recommended in Wayne's 2.2 to 2.5 but the whole issue of piston clearance scared me. Also, Wayne's configuration called for an E cam to go with the E pistons. Question: If I use 2.2E's can I still use a T cam and what would I use for ignition timing?

Thanks again.

The first thing you need to do is see what you have. If your pistons and cylinders are good, reuse them. 2.2T pistons with a 2.4 crank and T cams will give a nice street engine. You have to have the heads checked out to see of the valves, guides and seats are all within spec. Check the line bore of the case. Lots to do. If your cam has wear, get it reground to E spec or similar.

No matter what engine you build you need to check piston to valve clearance.

I went through the same decision making process and ultimately ended up getting a 2.7rs piston set (8.5:1). it's one of the less expensive sets out there and by the time you get custom pistons, cyls machined etc you are pretty close $ wise. nothing beats displacement. if you do go the 2.4 route you may want to consider getting a set of biral cylinders for better cooling rather than using the cast iron cyls... and I happen to have a nice set i'll let go for cheap!

Thanks for the comment and the offer. I don't have the engine apart yet so don't know what kind of cylindes are in it. Will be a bit yet befire I get to dropping the engine.

Your T is going to have cast iron cyls. Most people argue that these don't cool well enough for a higher displacement motor. That's why porsche put the biral cylinders in the 2.4 and higher performance 2.2 motors (E & S). If you are going to buy a new set of P&Cs def go with the 2.7 set, they are the most affordable and produce a great street motor that runs well on pump gas. Note that you should do all the case stuff when rebuilding to a higher displacement motor. case savers. studs. align bore. oil bypass. etc etc. only go to a very reputable machine shop.

Thanks again whackit. Any suggestions as to best place to get biral cylinders? ..... and what is what type of pistons should go with them? Thanks

The general rule of thumb is that the cast iron cylinders work OK up to a limit of 200HP in a 6 cylinder motor.

No one else has pointed this out yet, but since your car is a 2.4T, and the motor is a 2.2T that needs a rebuild, you may want to seriously consider selling the motor and simply finding a 2.4T motor for the car. The rebuild on the 2.2T motor is going to cost some significant money (i.e. north of $5k). That same $5k could be used to find a good running 2.4T motor which will make your car more valuable and will cost less time and money to get a good fresh motor in it. Second thing that makes this option an advantage is that a stock 2.4T will have more torque and more hp. This should be your first and best option....

I believe the case will need work to clear the pistons with the longer stroke crankshaft.

-Andy

you have to toast the bread first so its hard enough for you to spread it easily! Put the spread on one slice and the Jelly on the other toast! if it doesnt slide then just putting it in the middle and close it and it'll spread itself

I think so too. I don't remerber if it 's 2 mm or 4mm with 2.2S pistons + 70.4 mm crankshaft in 2.2 case

Thanks for all your comments on my upgrade underway. Would appreciate any additional comments on the above post as this is one of the upgrades in Wayne's book and he doesn't mention anything about additional case work to accomodate the additional stroke.

Also, my intent here is to stick with a pretty vanilla engine by staying with a T cam and T pistons. I'm not against other upgrades as long as they don't require changes ($$$) otherwise not required.

Thanks for your help Andy. If I go with 2.4 pistons can I then avoid the additional case work you suggested on my 2.2 case?

Dave