Advantage/Disadvantage of Bore and Stroke?

SE-Man · Post by **SE-Man** » January 12th, 2005, 2:02 pm

A K8 can be bored to the exact same as the ZE. The danger to over strokeing a cylinder is the piston "poping" out at high RPMS. and you can safely bore to 2.6 (and no, the skylines pistons will not fit, Guessing the block would heve to be bored to like a 2.75 with a short stroke.). I bored and stroked to 2.175L and i;m using a toyota's 1.5L pistons I do beleave. At 2,7 you can runsafly but with ABSOUTLY NO boost or n2o, and you'd want to stay in low RPM, and at 2.8L you block's integrity would be highly comprimisable. Its mostly the water chambers around the pistons were the weak points are. Thats assumming you keep the same stroke. Now if you got to 2.8L with stroke and bore, you'll likely have to keep it below 5K RPMs, or your sure to pop a piston out.

mrspanky79 · Post by **mrspanky79** » January 12th, 2005, 6:13 pm

no the k8 can not be bored to the 2.5l(ze and de have the same bore). Piston popping out at high rpms

if your having that problem there is much more wrong then your length of stroke. The only thing stroking a motor dose is lengthen the rev up time the longer the stroke the longer it takes to get to the higher rpms. It will still rev just as high the parts/balance and how well it is all put together controles the max rmps. And water chambers and block integrity have you even seen in a k series motor they are an open deck design so you would never effect the block integrity with what ever bore/cylinder sleeve you could fit in there. No offense but I still fined it hard to believe that you have your motor stroked. The only way to change the stroke on the motor is to change the crank or alter the crank. Changing size of the rods will only change the piston position they will still move the same distance up and down(the stoke).

kiwi_MX3 · Post by **kiwi_MX3** » January 13th, 2005, 1:57 am

right deep breath and here goes

The Lenght of the rod directly affects the performance of an engine!
A long rod will improve top end performance and also reduce piston
wear.
A short rod picks up bottom end performance but also increases wear.
How ever the short rod has a lot of advantages over the long rod due to
it accelerates the piston from TDC and BDC faster so eairler vavle opening
and also BIGGER vavles and ports can be used.

Thus pretty much being able to increase top end as well.....nifty aye

Con rod lenght / Crank Stroke = Con rod Ratio.

Most common are 1.5 to 2:1, 1.65 to 1.75.

Once you get down to a 1.65 ratio rocking of the piston in the bore can
be a problem though on my short course engine i was pulling the piston
right out to the base of the wrist pin.............
and who say you can't reva VW1600 flat four to 9000rpm

SE-Man · Post by **SE-Man** » January 13th, 2005, 11:21 pm

mrspanky79 wrote:no the k8 can not be bored to the 2.5l(ze and de have the same bore). Piston popping out at high rpms if your having that problem there is much more wrong then your length of stroke. The only thing stroking a motor dose is lengthen the rev up time the longer the stroke the longer it takes to get to the higher rpms. It will still rev just as high the parts/balance and how well it is all put together controles the max rmps. And water chambers and block integrity have you even seen in a k series motor they are an open deck design so you would never effect the block integrity with what ever bore/cylinder sleeve you could fit in there. No offense but I still fined it hard to believe that you have your motor stroked. The only way to change the stroke on the motor is to change the crank or alter the crank. Changing size of the rods will only change the piston position they will still move the same distance up and down(the stoke).

Why would you find it hard to beleave? Cuz I didn't do it myself? I'm not gonna lie, I didn't see it done. But the guy guy that did it, he had acsess to an entire machine shop, he could make any type of cam, crank, rod he wanted. He was a good friend of mine, I was an Evac Sargent, he was the mechanic in carge of my ambulances. You've seen nothing untill you seen a high 13 sec Armoured Hummer ambulance, and hes built a couple TTurbo hummers. I beleave he's fully capible, and wouldn't lie to me.
The power seaks for itself, I know its more powerful then stock.