crank it up

[gorgeous_shaun]

i have a 2.0 9000 FPT its a '90. is the difference between the displacement of the 2.0 and 2.3 the stroke of the crank or the bore of the cylinder?

thanks, shaun

[Marrk]

Originally Posted by gorgeous_shaun

i have a 2.0 9000 FPT its a '90. is the difference between the displacement of the 2.0 and 2.3 the stroke of the crank or the bore of the cylinder?

thanks, shaun

Its a longer stroke, the pistons are the same diameter.

[gorgeous_shaun]

Originally Posted by Marrk

Its a longer stroke, the pistons are the same diameter.

if i change the crank over then i got a 2.3?

[Superaero]

Connecting rods may not be the same. Compression ratio will be around 15% higher unless you change the pistons or head (not sure how SAAB does this).


More importantly, the 2.3 requires balance shafts to run smoothly. It is generally accepted that above 2.0 litres displacement a four cylinder vibrates excessively without balance shafts.

Of course several big four cylinder racing engines have been built without balance shafts (invented by Mitsubishi and most if not all engine manufactruers use a Mitsubishi license). Offenhauser Indy engines were huge fours. Ferrari built a 3.0 four. Porsche did also but used Mitsu licensed balance shafts for their production 944/968 engines.

[gorgeous_shaun]

Originally Posted by Superaero

Connecting rods may not be the same. Compression ratio will be around 15% higher unless you change the pistons or head (not sure how SAAB does this).


More importantly, the 2.3 requires balance shafts to run smoothly. It is generally accepted that above 2.0 litres displacement a four cylinder vibrates excessively without balance shafts.

Of course several big four cylinder racing engines have been built without balance shafts (invented by Mitsubishi and most if not all engine manufactruers use a Mitsubishi license). Offenhauser Indy engines were huge fours. Ferrari built a 3.0 four. Porsche did also but used Mitsu licensed balance shafts for their production 944/968 engines.

thanks for the reply, i totally forgot about ballance shafts! i have been reading up on tuning saabs and found its better just to keep the shorter stroke and more boost, all the trouble i will hve to go through ballance shafts, head, piston con rods all for an extra 300cc few horses and pounds of torque. even though these bits need changed in the tuning process its not worth it just now. just made up the extra power anyway with an MBC i installed earlier. very pleased with that! must be over 200 bhp and all for £67 for the car plus £5.50 for the MBC, unbelievable