3.2 cyls on 3.0 block?
 

Another member has 3.2 cylinders for sale and I'm interested if:

1) they'll fit an '81 3.0

2) they are nickasil

I would like to use them with JE pistons so I can run a larger cam. Are the 3.2 cylinders nickasil and will they work with my block and heads.

The 3.2 95 mm cylinders have the same dimensions as the 3.0 95 mm cylinders.
The only difference is the lack of CE ring (head gasket) on the 3.2 cylinder.
The 3.2 cylinders just like 3.0 cylinders can be Nikasil or Alusil.
Nikasil will work with JE pistons and Alusil won't.

Thank's Henry. I was under the impression that starting with the 3.0 head gaskets where eliminated. Are you saying they will work or do they need the ring machined it? Also how to tell if they are Nickasil?

Yes they will work.
The cylinders are interchangable.
Nikasil is basically chrome. It is shiny and magnetic.
Alusil on the other hand is Reynolds silicite. It is a process where the surface of high silicon aluminum is etched and then honed to produce a very hard surface. It is very smooth but not shiny.
If you have the pistons that come with the cylinders you can tell Nikasil from Alusil in that the pistons in a Nikasil set are forged and with Alusil they are always cast.

Thanks Henry. So they do they or don't they need the ring machined in? If they do where can I get specs on the ring? I have a machine shop and could machine the ring myself if I had dimensions, if it's even needed.

It still doesn't make sense to me, HELP!
SC 3.0 liters have cylinders with a ring-groove machined into them.
Carrera 3.2 liters don't have the groove.
And how do you acommodate the difference between a stroke of 70.4 mm (SC) vs. 74.4 mm (Carrera) and the effect on CR when placing a Carrera-cylinder on an SC-case???

They don't need the CE ring.
You can use them as they are, that is what interchangable means.

What about the difference in stroke??

Step away from the motor.
Your last question leads me to believe that you should not be working on these engines. JK :)
Pistons not cylinders determine compression ratio.
As long as the cylinders are the same height the compression ratio will be the same for a given piston. From Mahle or KS the cylinders are within .001".

If you are asking "how do you put 3.2 Carrera pistons on a 3.0 crank? " the answer is: off set the wrist pin bushing .030".

LOL! :D

Thank's Henry.

Does it feel good to be condescending and arrogant? :confused:

Don't fall off that high horse now. :rolleyes:

Gunter,

In defense of Henry I think is reply was rather tongue in cheek. Hence the "JK" (just kidding) and the smilies.

Henry,

I'm curious about the 3.2 pistons, you say by offsetting the wrist pin they can be run on a 3.0 crank and that they are all forged. What's the largest cam that can be run with that configuration? I was thinking about JE's but the 3.2 compression is just about right for me, I'm thinking about maybe a Mod S cam or similar.

Thank you for the advise. If I do fall off I'll get up, dust myself off and climb right back up.

I would like to take this opportunity to offer you some advise.
This forum is a place where men gather to discuss Porsche engines. If you are offended by my humor that's tuff. I don't care. Life is too short to worry about people, I'm trying to help, who complain about my delivery.
If your sensibilities are truly offended perhaps the Victoria Secrets forum, where they discuss bra fit and panty colors in a civil manner would be more appropriate for you. http://www.victoriassecret.com/

For those of you who grasp my obscure references, sense of humor and appreciate my experience, I will continue in the fashion I choose.

In response to a real question:
When putting 3.2 Carrera pistons on a 3.0 crank you are still faced with the limitation that squish chamber pistons offer.
20/21 cams are probably the most aggressive cam you can use safely.
It is however possible to pocket the Carrera pistons to afford you clearance you need for more aggressive cams. Even with fairly large pockets the compression will still be very suitable for street gas.

I've talked to Henry on the phone multiple times. Now that I can hear his voice in these posts, his replies crack me up. As with email, sometimes the typed word on these posts sanitizes intent and humor in a bad way.

As far as stroke differences, CR and deck height go, I was as confused as the next guy. Now I get it and hope I can pass my revelations along. Think of the increased stroke as more piston travel away from the head. 66mm vs. 70.4mm means you get 4.4 more mm travel away from TDC. Thus you get more volume in the cylinder when swapping cranks. As a result, when the cylinder is compressed, you are compressing the equivalent increase in volume into the same the same space as the shorter stroke crank did. Thus your CR goes up (more gas volume at BDC into the same space at TDC) without the piston getting any closer to the head. This applies as long as the inside edge of the journals of the two cranks are in the same location. The 66mm and 70.4mm cranks had the same location for the inside edge of the journal. This is why you get about .5 points more CR when swapping a 70.4mm crank into a 66m application.

I'm not sure if the journal locations are the same for the 70.4mm and 74.4mm cranks, but if it is, you can see why there isn't any worry in terms of pistons. I hope the above info helps.

kenikh,

I like Henry's humor as well.

Not to be harsh LOL but you've got the stroke thing half right, in your example the piston moves half the stroke length further from the head as well as half the stroke length closer to the head, hence the need for shorter rods or offset bushings. I may not be experienced with building P-car engines but I've done more than a few domestic V8's including stroker drag race engines. To me a long stroke engine is over 100mm :D

When the crank is essentaially an offset grind of the other ( the inside edge distance remains the same), how can the piston physically move closer give the same rod length?

There's a Victoria Secret forum?! Ummm, I'll be back in a few hours.
AM

The 3.2 rods are shorter @ 5.00" vs 3.0 rod @ 5.031"
The other difference is in the wrist pin location.
In the 3.2 Carrera piston the pin height is about .050" higher.
.031 + about .050" + about .080" = about 2 mm.

74.4 ( Carrera stroke) - 70.4 (SC stroke) = 4 mm divide that by 1/2 (the distance the piston moves in each direction) = 2 mm

To expand on what Henry said, if cylinder deck height remains unchanged the rods must become shorter as stroke increases. In some cases this can lead to severe rod angularity. A good example is a 351W smallblock Ford. At a 4" stroke with 4" bore you get a 402CI engine, it can be raced but longevity suffers a bit. Moving to a 4.35" stroke you get a 437CI engine that is only suitable for the street. The anglarity is such that the motor simply can't be revved without tearing itself apart. In some cases deck height might be increased with a special block, this is how they build the 600+CI mountain motors.

You sort of have to visualize the crank, rods and pistons moving to get an idea of what a change in stroke length will do.

Henry, if u can what would u approx. charge for a full rebuilt on a 83sc stock engine, with je 95mm pistons cr-9:8:1 and 964 cam,. tryn to keep CIS b/c of the price of carbs...4-5k. Im not worried about passing emissions and might run headers....Sorry to hijack this tread but i wanted to get it off my chest....thks guys....damian.., ps, what is shipping too from Hou,tx.