2.4 crank in 2.2S.. How would it affect resale value?

[hydra]

Hey all,
I'm a longtime lurker, and first-time poster. Glad to see there's an online community for early 911S cars, and there seem to be some very knowledgable people around here...

I've got an original 1970 911S, and I'm probably going to rebuild the engine soon. Now, be I've got a spare 2.4/2.7 crank/rod assembly handy, so figured why not stroke the engine out a little while I'm at it. It should pretty much a plug and play swap shouldn't it? Where would compression end up at? Would I need to modify the MFI pump to allow for the increased airflow or would it still be within adjustment limits?

Secondly, I'm concerned about the matter of originality. I realize that the 70-71 2.2S is a gem and is highly prized by Porschisti so I'm not sure I should alter it in any way, but on the other hand its a great idea (on paper at least). With that in mind, would a mod like that have any negative (or maybe even positive?) effect on the value of the car? What do you guys think, would you do it if you were in my shoes?


PS Were all 2.4/2.7 cranks created equal? If not how do I tell the difference between them?

[Fritz A. Ficke]

My two bits, The 70-71 S was prized becouse it is the last of the high reving short stroke engines. Stroking it will be detuneing it in many people's mind maybe the one's writing checks when you sell. Do you have to change pistons with the longer stroke? should you put a milder cam's in to make a long stroke engine work in it's new RPM range, to help take advantage of it's new torque? The componets or pretty balenced with each other and I look at mods. at best as a side ways move, unless it was a factory update, piston squiters, Carreara oil pump, oil coolers, etc. or after market can be good like pop off valves on CIS air box's or collers on old tensiner's. If you want to modify for power do a complete job on another engine and save your "S". If you do not have money to go all the way I would advise not going part way, you will have a comprimised engine that will appeal to few, maybe even your self included Oh one more thing I am not coming up with this advice on theory, oh no I had to learn by doing Good luck have fun, and yes I am one of those who really prize 2.2 'S' engines

[fryardds]

Hi Omar,

Welcome to our little gathering place. I have to agree with Fritz. I think the stock 2.2L S motor is a real gem. Short stroke, high compression, and fast revving package of fun. I am in the later stages of an engine rebuild on our 2.2L S Targa and I made it a point to do it completely stock. I didn't even modifiy the 'S' cams to a milder grind. I really wanted the original performance and attributes from this motor. Does your motor still have MFI? Be sure to post from photos of your car in the "Show us your ride" thread.

[Zeke]

I own a 2.2 S. And I have a 2.4 T motor to build. I would save my mods for something like that (as I am doing) and hold on to the 2.2, especially if the numbers are correct.

And, yes, you would have to change the pistons. At least the rods. And by changing the rods only, you would end up with nearly 11:1 compression.

[hydra]

Zeke,
I mentioned that I would be dropping in a complete 70.4mm crank/rod assembly. The 2.2mm greater crank throw (70.4-66/2) would be offset by the ~3.5mm shorter 2.4/2.7 rods, so while I'm not yet sure where that puts compression yet, I am sure it WON'T be at 11.1 . I'll check with my Compression Ratio calc program as soon as I get back home...

Oh, and it was my understanding that I wouldn't have to change pistons (2.2S pistons are a popular mod for 2.4S motors right?)

Fritz,
About stroking the engine, its only a 6.7% increase, I really don't think that would make the engine any less eager to spin, all it would do is increase torque across the rpm range and make the engine even more of a gem. The 2.7RS/2.8RSR have the longer stroke crank, but they still rev to the moon don't they? But maybe part of the 2.2S appeal is in its relatively gutless low end torque, and the kick you get as the revs rise and the engine comes on cam? Is that what you guys reall mean? If it is, how does driving a 2.2S compare to driving a 2.4S?


I'm all about keeping a matching numbers car, so this would have to be done to my existing 911/02 case... Rest of the car is original, and yes Brian, its still got the MFI setup - which I will probably end up rebuilding as well! The car is currently undergoing an exten/pensive restoration, and is thus currently quite camera shy. I don't blame the poor thing judging by the quality of some of the cars there!

PS Brian, send me some pics of your car sometime...

[rvdv]

I also have a 2.2s which I purchased in 1977, the 2.2s was a blast to drive in my younger years, that rush at 5200 rpm was awsome, but as old age set in I wanted something that was more relaxing to drive without the power loss, I needed something that I could drive at 2000 rpm. So I built a high compression 2.4. I used a 73T 7R case, 70.4mm crank with 2.4S rods , 2.4S heads , 2.2S pistons "E" cams and a 2.2S MFI system. The only issue I had was that the pistons just kissed the webs in the case at BDC so I machine about a mm off the corner of the skirts, problem solved. The is an awesome running engine with way more grunt at low RPM's, it pulls strong in 5th from 2000 RPM and up, and yet will still rev to 7300. I never had the engined dynoed but it feels way stronger than my 2.2S motor. I don't recommend that you build this with your 2.2S, keep it original, if you ever sell the car I'm sure that an original engine with original parts will command more $ for the car. If you do decide to build one of these engines though I can guarantee you that will not be dissapointed.

Rudy

[Zeke]

Hydra, you're right, I didn't read it thoroughly. So, you change the crank and rods. Here's what I do know: As you say, a popular mod is to install 2.2 rods and pistons in a 2.4. My understanding is that the compression of each model of piston will be higher installed on the 2.4 crank. As it is, the 2.2 S piston makes 9.8:1 in it's own motor. You make your own conclusions from that. It will be in the tens, that I know.

[Mr9146]

I have a 2.2S case with 2.2S pistons and cylinders stroked with a 2.4 crank. It's got 2.4S mechanical injection with plastic stacks. The compression is about 10.8 or 11:1, and anyone who's seen/driven the car can attest to the fact that it's an absolute screamer. I would HIGHLY recommend the modification if you want a FUN motor that is very tractable around town albeit a little lacking in the torque department - hey, it's got no displacement.

Or, I'll sell you mine for $8,500.


PS: The rods are the same between 2.0, 2.2, 2.4 and 2.7.

[hydra]

Zeke,
I did the math, and a 2.4 crank/rod combo in an otherwise stock 2.2S should be good for a compression ratio of 10.3:1, which I suppose should be good for just under 200bhp

Assuming I stick with the original engine case, there's really no way to prove that the internals have been tampered with (unless I do a compression test, but even then the difference isn't that large) maybe it would be obvious once the car is actually driven...

Mr9146, the 2.0/2.2 & 2.4/2.7 rods ARE different. The former are around 3mm longer while the latter have a 2-3mm smaller rod bearing diameter and a different width. I don't have the exact figures handy right now, but a quick websearch wouldn't go amiss...

Any word as to there being any differences between regular 2.4/2.7 rods/crank and 2.4/2.7 "S" rods/cranks?

[Mr9146]

Zeke,
Mr9146, the 2.0/2.2 & 2.4/2.7 rods ARE different. The former are around 3mm longer while the latter have a 2-3mm smaller rod bearing diameter and a different width. I don't have the exact figures handy right now, but a quick websearch wouldn't go amiss...

Any word as to there being any differences between regular 2.4/2.7 rods/crank and 2.4/2.7 "S" rods/cranks?

Yeah, I screwed up. The 2.0 and 2.2 are the same crank and rods, and the 2.4 and 2.7 are the same crank and rods. It appears that, indeed, I am human.