Engine question

[9000CS23T]

Question for the experts. Can you put a 202 head on a 234 engine without any problems? Pre 93 in both cases.

[wrighar]

I would think so, you can do it the other way so they should be compatible.

Andrew

[Stewart]

What about the timing chains, the 2.3 is a taller engine is it not, therefore the t/chain from the 2.0 would be to short.
Or am I just talking pants!

[zeppelin]

im with scaero on this i think you can,but we both know who to ask.

[Stewart]

Right!, where's the man who know's, where is he!

[mark e]

IIRC it affects the compression ratios- the combustion chambers are certainly a different shape, with the 2.0 being squarish and the 2.3 round. I'm pretty certain that putting a 2.0 on a 2.3 increases the compression, which is OK as long as you don't want to run higher levels of boost.

Doing some maths on this:

the B202 Turbos were were 9:1 compression ratio, and with a swept volume of 1985/4=496cc per cylinder, have a combustion volume of 55cc

the B234 Turbos were were 8.5:1 compression ratio, and with a swept volume of 2290/4=572cc per cylinder, have a combustion volume of 67cc

If we assume that most of the combustion is in the head (OK there's a small amount in the dish of the piston) that would suggest that putting a 2.0 head on a 2.3 would give a compression ration of 572/55 or about 10.4:1

The extra displacement is achieved by a longer stroke, and "room" for that is made at the bottom of the block.

More info on the engines can be found on Saabs.info

[Stewart]

Mark...What about timing chains?, or is this just rubbish cause I was sure the 2.3 was "taller".

[zeppelin]

ask the man.

[rhino2.3t]

(pants) *cough*

[Stewart]

I did, but it's very technical now!

[wrighar]

Originally posted by Axl:
[qb]Mark...What about timing chains?, or is this just rubbish cause I was sure the 2.3 was "taller". [/qb][/b]

Tis Rubbish I'm afraid, the 2.0, 2.1 and 2.3 heads up to MY93 are bolt and patten compatible between cars.

Andrew

[wrighar]

Also the 2.3T head have larger (exhasut?) valves, but not by much I think, and not as larger as the Abbott big valve conversions.

Andrew

[Stewart]

Oh well, thats me told!!, I was sure they were taller, obviously not, well at least I know now, cheers

[wrighar]

The 2.3 engine block casting is not compatible with the old 2.0 casting used in the C900's as it is too tall and not cast for a 45 degree slant.

The later GM 900 2.0 engine casting is also too tall as it was recast for near upright use.

This is probably where your confusion comes from.

The older engines were 90mm diameter and 78mm throw for 2.0 and 90/90 for 2.3 with a 6mm longer throw crank (which is to big to fit the C900 sump without fouling).

Andrew

[wrighar]

Google's great

Head Displacement:
When swapping heads around, it's important to note that the shape & dimensions of the combustion chamber is't the same. *The following info comes from Nick Jacob:

B201 48CC
B202 *(MY1985 only) - 42CC
B202 46CC
B212/B234 (essentially the same head) - 48CC

With that information, you'll see that putting a B212 or B234 head on your B202 motor will drop the compression ratio, and putting a 1985 B202 head on any later car will substantially increase it.[/b]

Although a 1996 on B202 head will not greatly impact CR.