Factory Forged Con-rods on some 944 NAs!

[1.2gees]

I just noticed a little interesting fact last night...

Cars produced in (january) 1984, and earlier have Forged con-rods, whereas the later cars have cast... I'm talking about the 8v NAs.

Interesting fact huh?

Considering that the 2.5 liter cars all use the same forged steel crankshaft, if made to run cool (-er), and with lots of fuel, these engines should be able to handle a LOT more power)...

This I decided to post after reading the NOS post, liners would seem to be the only part that MAY not be up to par with the rest of the engine for ultimate potential, but I personally don't see anything wrong with up to at least 220 or so hp on an (extra!) early 944 engine.
Ahmet

------------------
It's all the driver...

[mike944]

how do we find out the build date?

i have an '84NA i'm curious to know if i have these forged rods.

Mike

[todd951]

There's a sticker that has the build date and some other information on it. I forget where it is, but I think it's on the driver side of the engine compartment.

[1.2gees]

Well, if your car's an 84, it'll have the forged conrods... Keep in mind, a car sold in 84 was most likely built at least 4-8 months before that, likely a little more.

todd is right, there's a sticker somewhere, and I'll get the exact location, and make sure that the date they switched over is january of 84 (I know it's 84, not positive if it was in january).

I'd suspect that all early ones had forged, or at least up to 84, will find out once I get home. (I'm at school right now).
Ahmet

------------------
It's all the driver...

[lm6y]

You should be concentrating more on school and less on this BBS! Find out for sure when the cutoff date is. If possible make sure it is after Oct. '84, so my car will have them!

[1.2gees]

Well, my English paper is on "Porsche in MOtorsports"... So I suppose I'll be alright for a while!

It was cars after February 1984.

That's cars made after February 84...
Ahmet

------------------
It's all the driver...

[1.2gees]

Well, I thought I'd add, after checking the factory manuals, you can mix-match the two types of conrods in the same engine...

I would think that would throw off the engine balance, but cannot find any info on how much they weigh (at least not yet).

Interesting yet again huh?
Ahmet

------------------
It's all the driver...

[lm6y]

Ahmet, you are THE king of obscure knowledge!

[wannaberacer]

hey,
I think I remember a date being on the rear bumper. I was replacing my fuel filter and looked at it, and it said april 84. So hope that answers your Question.

P.S. this is a great forum! I have been reading everyones posts and they are all great! Hope to be of some help. This is my first post.

[1.2gees]

Welcome to the board.

The date on the bumper was probably the date that part was manufactured in, so your car's likely a late 84 or (more likely) an early 85.
Ahmet

------------------
It's all the driver...

[pst]

1.2gees, what NOS post are you refering to? I'd like to read it.

[1.2gees]

There was a post on nitrous usage (there's been another one since my post), nothing about the engine's strength was mentioned there...

I read the post, and kept on researching about the block/engine.

Considering that the 944 engine was engineered from the beginning for "at least twice the power", I don't think there'd be a problem with trying to get more (serious) power out of the NA engine.

The S2 block was produced with plans to "bore out to at least 3.2-3.4 liters", however declined interest, and continually worsenning sales, as well as the profit margin decreasing forced the management to thrash all the plans.

(I found out that the eventual 3.4 liter 16v 968 turbo was planned!) The 2.5 liter block was first engineered to be capable of being bored out to 2.7 liters, with extremely high compression (however emmissions/fuel required/build cost favored the turbo, read on) or turbocharging was planned. When they decided to keep the 911 alive instead (in 1981), the 2.7 liter turbo plan was scratched.

The block/crank is VERY strong on the turbo, but the NA block really should be able to handle 300+ft/lbs of torque easily. Keep in mind that the crank is the same between the cars, on the block, the (thickness of)linings are the only significant down side when comparing the two 2.5 liter blocks. Even the 5 main crank bearings (which is more than the usual 4) are the same...

Anyway, with proper cooling (aided by a somewhat rich mixture), and timing, there's no reason for the NA block to be weak for the power figure I posted above.

Another reason to why the 3.4 liters of turbocharged power wasn't a good idea is that Porsche was considering the build of a VERY light total rotating mass, with huge pistons, but comparatively short stroke. This causes the power strokes to be a lot more noticable, having only 4 cylinders. "What you feel is the power being produced, and not the mass", indeed if a cylinder makes 100+hp, it won't run too smooth, there's no way around it. Keep in mind, the 968 unit isn't quite as smooth as the 944 engine, making a tad over 48hp/cylinder if I remember correctly...

The 3.4 liter 16v turbo would've only been successfull as a VERY low volume car, which would'nt be competitive.

OK, since I've gone this far:

The 968 was in the same catagory as the 911 RS, (but it did outperform that car around a track) however it was a little more expensive, and didn't have the 911s heritage. (As I've explained the car/chasis definately had the potential).

In 911 terms, the 924 is comparable to a 356, and the 944 turbo S (or 968 turbo S, as it only had a few bolt on mods) would be like a 911 SC. In other words, it had huge potential left in the platform, that went unexplored.

This is why I want a 968, hoping to get some real, reliable, driavable power out of it.

Well, there's a post longer than needed to answer your question, but I hope you enjoyed it.
Ahmet

------------------
It's all the driver...

[pst]

I was reading through the factory repair manual last night looking for anything to verify the forged rods. What I had remembered was that the early 944 rods were made of sintered metal. This is the case. The manual refers to the early rods at the beginning of the manual as "forged" but later describes them in more detail. Up to February 1984 the rods were sintered metal. From February 1984 the rods were cast. Sintered metal was also used in the 928's and is a process where powered metal is put into a mould then pressed and heated to form a very precision weighted part. This was good for weight control but had some reliability problems. Hence the change to cast. This is also verified in other books that I have that discuss the development of the 944/928 engine. From what I have read, It is more common for builders to use aftermarket rods such as Carillo because of the increased strength and significantly lower cost.

[1.2gees]

"Sintered metal was also used in the 928's and is a process where powered metal is put into a mould then pressed and heated to form a very precision weighted part."

I have to ask, how "sindered" differs from "Forged". I'm surprised you point this out, and go on to say that in the manual it says they're forged!

Which other books on 944s have you read? I have virtually every title ever published with "944" on the cover! I'd like to cross referance.

BTW: I was thinking cost was a better reason for the switch then reliablity. The fact that the forged con-rods didn't supercede the older part seems to favor my hypothesis.

Please provide more specific info if you can.
Ahmet

------------------
It's all the driver...

[kaffine krazed]

Forged parts are made from a solid piece of metal stamped into shape then machined.

[eimkeith]

Ahmet, where are you reading all this? I'd like to read it also...
Thanks.

[1.2gees]

redNeckarsulm:

My info comes from the factory manuals (latest copy available, modified in 1992), as well as an array of Porsche history books, including Porsche Chronicle, Porsche in Motorsports the first 50 years. Original Porsche 924/944/968, Porsche 924/928/944/968.

Well, incase there's any confusion:

Forging is when you heat up a solid piece of metal, and press the mold onto it (usually at very high pressures), then machining as necessary. Casting differs, in that liquid metal is poured into the mold. Sintering is much like forging, except the metal is not melted.

OK, here's the thing, sintering can be considered a form of forging!

If anybody disagrees, I'd like to hear from them!
Ahmet

------------------
It's all the driver...

[wolfrpi]

Forging is not limited to "heating" the metal. There is also a process called "cold forging" which I believe to be even better.

Erick

[wolfrpi]

BTW - Generally, sintering is a process used whereby metal powder particles are bonded together metallurgically in a pressure controlled high temperature furnace.

[wolfrpi]

Forging - The act of plastically deforming metal into desired shapes by hot or cold fabrication methods, utilizing the ductility and malleability of metal by exerting compressive force upon it.