How to build 2.2 with 9:1 compression

Vintagemotion · 01-21-2009, 07:08 PM

Using the original crank and boring the original cylinders - what option do I have to get 9:1 compression?

Who makes such pistons?
What can be done to crankcase or cylinder to increase compression?

thanks

RJ

kenikh · 01-21-2009, 07:24 PM

Use 2.2S pistons...you'll find that they cc out much closer to 9:1 than 9.8:1.

JE will make pistons to any spec you want for reasonable money, too.

Vintagemotion · 01-26-2009, 02:25 PM

Quote:

Originally Posted by kenikh

Use 2.2S pistons...you'll find that they cc out much closer to 9:1 than 9.8:1.

JE will make pistons to any spec you want for reasonable money, too.

Solution:

JE pointed me to EBS racing. They have 85mm millimeter JE pistons that are custom made for 9:1 compression on the stock 2.2 crank. They said boring 84mm stock steel cylinders is no problem.

kenikh · 01-26-2009, 02:28 PM

Yep - that'll do dandy. I don't love the iron cylinders, but as long as you don't go racing it, heat soak shouldn't be an issue.

Vintagemotion · 01-27-2009, 04:55 AM

Quote:

Originally Posted by kenikh

Yep - that'll do dandy. I don't love the iron cylinders, but as long as you don't go racing it, heat soak shouldn't be an issue.

besides the weight - what's the issue with cast iron?

kenikh · 01-27-2009, 04:59 AM

They really suck at cooling, so only low HP applications apply. That's why Porsche only used them on 'T' cars - well that and they are cheap to build.

304065 · 01-27-2009, 05:23 AM

I'm confused, a 2,2E was originally 9,1 compression, why not just use E pistons?

Vintagemotion · 01-27-2009, 08:39 AM

Quote:

Originally Posted by kenikh

They really suck at cooling, so only low HP applications apply. That's why Porsche only used them on 'T' cars - well that and they are cheap to build.

OK , I did not know that only the T came with cast iron. Is this true for all years the T was made?

ajwans · 01-27-2009, 01:57 PM

Quote:

Originally Posted by Vintagemotion

What can be done to crankcase or cylinder to increase compression?

Crankcase and/or heads milled.
Rod small ends offset bored (not strictly crankcase or pistons but cheaper than either)

Any of these will bump your compression a bit.

andy

Brant · 01-27-2009, 08:54 PM

Quote:

Originally Posted by Vintagemotion

OK , I did not know that only the T came with cast iron. Is this true for all years the T was made?

yes

I believe the really early cars (64-66) ran iron cylinders
the 67-73ish went to biral cylinders in the S/E models
and then nickies and alusil on the 2.7's

but I believe all T's used the iron cylinders.

tom1394racing · 01-28-2009, 01:25 AM

"I believe the really early cars (64-66) ran iron cylinders"

Is this correct?

I though only the T motors had the cast iron cylinders and the the early motors used birals.

304065 · 01-28-2009, 05:18 AM

Quote:

Originally Posted by Brant

yes

I believe the really early cars (64-66) ran iron cylinders
the 67-73ish went to biral cylinders in the S/E models
and then nickies and alusil on the 2.7's

but I believe all T's used the iron cylinders.

Brant, actually all the early motors (production of course, I am excluding chromal and exotic prototype stuff) until the introduction of the 911T in 1968 used Biral cylinders. Nikasil came in with the 917 in 1971 and was used in the production cars from 1974. ('73RS was Nikasil)

Tom Butler is correct.

Brant · 01-28-2009, 06:54 AM

John, Tom,

you both know so much more than I
I completely defer...

I didn't realize the early cars used biral, but I am sure you are right
brant

Vintagemotion · 01-28-2009, 02:19 PM

Quote:

Originally Posted by kenikh

Use 2.2S pistons...you'll find that they cc out much closer to 9:1 than 9.8:1.

JE will make pistons to any spec you want for reasonable money, too.

Thanks for all the good info!
Another question: What does the compression height of the piston need to be in order to get 9:1 with a 2.2 crank?

RJ

TimT · 01-28-2009, 04:35 PM

Quote:

What does the compression height of the piston need to be in order to get 9:1

why so hung up on 9:1?

Get some off the shelf 9.8 or 9.5 pistons and be done with it? or maybe the 10.5 that JE makes...

Lots of options, and not so much mystery

tom1394racing · 01-28-2009, 04:39 PM

If you use 2.2 pistons with the longer stroke 2.4 liter crank the CR will increase about 0.55 pts due to the longer stroke.

So 2.2T pistons would produce 9.1 CR, 2.2E pistons would produce around 9.7 and 2.2S pistons would produce around 10.3 CR with the 70.4 mm stroke 2.4 crank.

Your best bet for street driving on pump gas would be either the 2.2T or 2.2E pistons.

ajwans · 01-28-2009, 05:27 PM

Being a T you probably have a non-CW crank in there currently.
If you wanted to stroke it this would be a excuse to get a CW
crank.

andy

Vintagemotion · 01-28-2009, 05:49 PM

Quote:

Originally Posted by ajwans

Being a T you probably have a non-CW crank in there currently.
If you wanted to stroke it this would be a excuse to get a CW
crank.

andy

What do you mean by CV?

Vintagemotion · 01-28-2009, 05:52 PM

Quote:

Originally Posted by TimT

why so hung up on 9:1?

Get some off the shelf 9.8 or 9.5 pistons and be done with it? or maybe the 10.5 that JE makes...

Lots of options, and not so much mystery

9:1 will give me the most efficiency / power without having to worry about gas quality.

Vintagemotion · 01-28-2009, 05:58 PM

To look at this a bit more quantitative I still like to know what the compression heights of a 2.2E, 2.2T 2.4E 2.4T. Distance wrist pin to piston top?