Rebuild and Upgrade a 2.2s
 

Well, I thought the 2.7 was going to get worked on first, but I guess not....

What we have here is what started life as a 2.0 914/6 engine. It has already be upgraded to 2.2 with S Pistons and an E cams. I want to keep the original case so the numbers continue to match. This is for an Early 914/6.

Upgrade path - I'd like to try re-use the P&Cs. Stroke the Engine with a 2.4/2.7 crank and rods. Do a general "freshening". Also will do the Chain Tensioner upgrade. According to "The Book", this should become an engine with about 10:1 compression.

Are there other upgrade considerations? Is this a reasonable path for my engine?

James

Why not keep the 66mm crank and add some 90 mm pistons for a 2.5l monster. You could do some high comp. pistons and really have a screamin' beast. The case has already been cut for the 2.0 to 2.2 upgrade so what's a few more mm?

I like the idea of stroking the engine to increase the torque band. This is a street vehicle. I certainly would consider 90mm pistons if they are resonably available.

James

James;
Capacity is capacity. It really doesn't matter if it is boring or stroking. The torque curve will most likely be comparable either way after adjusting for the engine size.

If you stroke the motor with the 2.4 crank, you'll have a CR which is really too high for street gas without twin plugging. So unless you're planning on going that route (and incurring the expenses involved in twin plugging), you'll need to have the piston machined to bring the CR back down below ~9.9:1. The good news would be that you won't need to bore out the spigots and further weaken what I assume is NOT a 7R case.

On the other hand you could go the big-bore route. In this case the savings would be that you don't need to buy a new crank. The extra capacity given the same combustion chamber size will still boost your CR, so you'll still have that problem to deal with.

The other thing to think about is your head constraints. A 914-6 motor is basically a 2.0T which had smaller valves(42i/38e) then the 2.2 and later motors (46i/40e). This and the 32 mm intake port size will most likely limit you to about 160-170 HP no matter what you do. If you want more then that you'll most likely need to get the heads ported and/or replaced with the later model heads.

I guess I'd recommend the 2.4 crank idea since you get to keep your pistons and not weaken your crankcase by boring the spigots. The longer stroke won't be an issue since the heads will be limiting your maximum engine rev's any how.

I'm pretty sure the heads were upgraded at the same time. Aren't the 2.0 heads incompatible with the 2.2 cylinders?

Do you have a source for the 90mm P&Cs?

James

Actually, I think it's the other way around - the 2.2-2.7 heads have trouble with the 2.0L pistons & cylinders.

-Wayne

You can get the 90mm RS P+C's for about $1400.

EBS and a few others have them.

James-
In order to get a short-stroke motor with a decent compression ratio you need to find pistons intended for long-stroke, twin plug applications (RS pistons will only get you something like 7.0:1). Mahle makes such a thing, but they cost about 3K. I'm building a short-stroke motor very much like what you are considering. I will be using JE pistons and reconditioned cylinders. This costs about $2050 from EBS, including a $300 core charge for the cylinders. You may, however, have some other issues to resolve. Nikasil cylinders require the use of piston squirters. Your early case would need to have these added. The long-stroke idea sounds a lot cheaper, and, as Jluetjen pointed out, will result in a very similar motor.
-Scott

The three motors I have are as follows:

2.2S - S Pistons and Cylinders on an original 2.0 Case, either E or S cam
2.2T - AFAIK it's stock
2.7 - Needs the case worked for pulled case studs.

In my possession - a 2.4/2.7 crank and rods

Should I leave the 2.2S alone and just "freshen" it and stroke the 2.2T with the 2.4 Crank? Should I stroke both by sourcing another set of rods and crank? Should I sell all of my Porsche cars and buy a Honda?

James

James-
What is your budget? Given the money I'd say you should build a 2.7. You have the case, rods, and crank. You could buy a set of RS pistons (excelent value), as mentioned by Bobby, and use the 2.2T heads. these would be better if ported. You could then use your E cams, or S cams. The pulled case studs are not that big of a deal, as you should have case savers installed whatever your decision.

Well, I have 2 vehicles....A 1974 911 (The owner of the 2.7) and a 914/6. And the 3 engines.

So you think I should take the 2.2T case and build a 2.7 with the 2.4/2.7 case and a set of 2.7 P&Cs.

Budget. My preference is as cheap as possible. However, I want to do a decent job and not use too much money from my recent re-fi. And I definitely don't want to spend more than I could buy Waynes 1982 SC for on Ebay...

James

The reserve is less than the average engine rebuild...

-Wayne

Yeah but what are the chances it's gonna stay that low?

Hmmm already up to $7000.

Do you really have a 2.2S motor? If you are using the original heads, then the valves are not the proper size, and the ports may be just 32mm. This means that what you reallly have is a 2.2E with a little more compression. How about this: get the 2.2T heads ported. Determine if your T case is a '71 or a '70. If it is a '71, it will have piston squirters. If not, you could have them added. Build a high compression 2.4S motor using the 2.2S pistons and cylinders, ported T heads, S cams, T case, t crank and rods, and your carbs. Put the original case on a shelf somewhere to save for a posible future numbers-matching restoration. If you have any money left then you can deal with the 2.7.
-Scott

The 2.7 is going to be a standard rebuild, as I expect my Girlfriend will end up driving that one and I don't want to give her too much power.

Well, the 914/6 motor is supposed to be S spec right now, but I think it's really running an E cam. It may not. PO wasn't the nightest bulb in the sign.

I'm going to "evaluate" the 2.2T this weekend, and determine if I can just run it and stick that in the 914/6 while I rebuild it's motor. I really need to have body work done on both cars so I may just buy Waynes SC and not care for a while ;) .......

Well, at least we know what the reserve was set for...

Well, there I go. I bought Waynes car _AND_ I'm doing a rebuild on the 2.2.

I'll keep you up to date. They are dissasembling the long block today. I get to find out what the Franken-motor really is.

S Cams or E? T pistons or S? Was it really a 2.2? Stay tuned.

Anyone want to buy a 1974 Straight targa Roller?

James

Interesting thread. I am at a similar decision point, although my car is "almost" a dedicated track machine so my needs are somewhat different. I have a factory -6 motor with 2.2S P&C's, cams, and dizzy. It breathes thru Weber 40's and Bursch headers with either megaphones or a Dansk 2-in/2-out sport muffler.

I had been tossing around doing a 2.4-2.5 stroker or short-stroke (big-bore) modification. High C/R is not a problem as long as I can stay single-plug and run race fuel.

But...I am pretty sure that I too am still running stock 2.0T heads so there has got to be a ton of power "tied up" in the heads. I figure I will start there first and perhaps put in hotter cams too.

I already have a short-geared trans so keeping the revs up is not a problem any more.

So now the question is...what port & valve sizes and what cams? And then carb jetting will be the next big issue.

Well...

When we pulled my motor apart...it turned out to be a 2.2T, not an S as the PO had claimed.

The P&Cs were usable, but barely in spec and so I decided to replace with 2.7RS spec P&Cs and I upgraded to S cams.

Heads were ported along with the intake manifold. It should make a quite a bit more power, even though I left the compression ratio at 8.5:1

James

ChrisC;
Before I can offer an opinion on your situation, I have a couple of questions...

1) Do you race your car at all or just DE? The reason that I ask is because if you race, the rules will often define your path.

2) How fast do you want to rev your motor? In broad terms, there seem to be 2 categories of race engines. Actually there are more, but if you're already running S cams, we can ignore the slower options which are based on stock T or E engines.

a) Engines running S or similar cams and rev'ing to about 7500-7800 RPM redline. Peak torque is above 4500 RPM and peak HP around 6800 -7000 RPM. Basically modified S engines. In general, if well built these engines should last as long as a factory S engine.

b) What I would call "Full Race" engines running 906 or GE80 type cams. These have a redline at 8000 RPM or above, peak torque at 5000 RPM or above and peak HP above 7000 RPM. These are more analogous to an RSR or IMSA GT engine. The top end (heads and valves) life of one of these engines will generally be measured in events (actually hours) with the bottom end good for 1 or 2 seasons.

How wild do you want to go?

I know of 2 sources, one new, one used for the 2.7 RS P&Cs. Crank and rods for a 2.4/2.7 are not difficult to find.

Or you could go with standard 2.7 C's and run J&E pistons with whatever CR you want.

And yes, larger valves will help.