2.8 rod in a 3900

[96ols60degree]

As of now,still not 100 percent sure what engine,if any,i will build for my 96 ciera.if enough stuff becomes avalible to put 3900's in our older plate form's,well my question is,how about using a 2.8 rod in the 3900,for a big bore ,short stroke engine? Do you undertstand where i am going with this?

[WrathOfSocrus]

The rod length has nothing to do with the stroke it is the crank that gives you the stroke. The 2.8 and 3.1 had the same rod and different cranks. The pistons had to be made different in order to make Top Dead Center land in proper relation to the head. Changing just the stroke will put the piston in a different location, so the rods, piston, and stroke must all be accounted for to get your quench right.

[96ols60degree]

whether you believe me or not,that is really what i was asking. but you still did not answer my question,is this doable,and can you make a short stroke,big bore combo like this? wouldn't this be good for racing in theory? or should i go for the cubes? is this as big as a 60 motor will go?

[Joseph Upson]

can you make a short stroke,big bore combo like this? :

It's called a 3500 VVT, 3.9" bore, 3.00" stroke, same as the 3900 VVT except for the crank, 3.00" instead of 3.31". Rods are not interchangeable with the 2.8L because the crank pins in the newer motor are larger in diameter.

[96ols60degree]

sO I GUESS WHAT YOU ARE SAYING IS I WOULD NEED CUSTOM RODS TO DO THIS? SOUNDS LIKE A LOT OF WORK. SO STILL NOT ANSWERED,IS 3900 AS BIG AS A 60 WILL GO C.I.D WISE? SAFELY THAT IS.

[geoffinbc]

Yes 3.9L is as big as it goes. But if you want a big bore short stroke motor then use a 3500VVT engine in your car. No custom rods or machining

[96ols60degree]

So the 3500 vvt is different than the one that I have in the wrecked 04 malibu? I dont think this car has vvt?

[geoffinbc]

Yes they are different. The bore and stroke are different. Check the Specifications section on this site.