Stroke It???

[darkone]

how far can you stroke a ka? ive been told up to 2700cc and what rpm would you be able to reach with a stroker kit?

[grip_racer]

why dont you bore it over a little instead? its already stroked to hell.

just askin.

[:: orion ::]

Stroking a KA is a BAD way to try to make more power...

Here's a quick explanation, from "Ask Sarah" at NissanPerformanceMag.com:

[quote=""Ask Sarah""]Confucius say "There's no replacement for displacement." OK, so it wasn't him, and that doesn't include forced induction which can give any sized engine a "boost" in power. But everything else equal (such as efficiency), larger capacity engines will produce more power because they can burn more air and fuel. Displacement is a factor of bore (size of the piston) and stroke (distance the piston travels up and down). You can increase displacement by increasing the bore with a larger piston, increasing the stroke by moving the pin further out on the crank, or both. The more reliable and efficient way is to increase the bore and stroke in equal proportions. Increasing the stroke gives the engine more leverage to rotate the crankshaft, upping torque for greater low rpm power. However, you can only stroke so much before you blow. Piston speed is a product of both stroke and rod. The highest velocity is when the crank to the rod is at 90 degrees. If the rod is longer, 90 degrees is reached further down the bore so it gives more dwell time at TDC (it will be going away from TDC at a slower speed). Plot velocity at crankshaft rotation and it's much less pointy at TDC. Since the piston accelerates from TDC slower, it gives cylinder more time to fill, which means better breathing at higher rpm. By the way, increasing rod length will not increase displacement but it will allow you to accommodate a larger piston that might hit the cylinder head. Peak piston speed is determined by stroke and rpm. Piston seeds increase as rpm rise. With the 96mm stroke on the KA24DE, at redline, peak piston speed is approaching 3890ft/min. You would increase displacement about 100cc for every 4mm increase in stroke length. That 2.8L goal would require a 108mm stroke! To maintain a safe peak piston speed of about 3500-4000ft/min, a 100mm stroke is about as large as you'd want to go. A 108mm stroke would result in a redline of 5900rpm to maintain safe peak piston speeds. Too high a piston speed can lead to ring seal and lubrication issues and a shorter piston life. A longer stroke would need a lower redline. A low rod to stroke length is good for the low end torque but it doesn't breathe as well top end. With a longer rod, the redline could be higher but you'd lose low end power.

...

You can achieve your higher displacement goal if you overbore to about 91mm, reweld and offset grind the crank, for about 2.7L. Get forged racing pistons such as those from CP or JE Pistons, which can accommodate the OEM piston rings and should be used with Carrillo steel connecting rods with 3/8" SPS bolts rated at 220,000 psi. Otherwise, start saving your money for the rebuild! The engine won't rev well or last very long but it will have a large displacement.[/quote]From here:

http://www.nissanperformancema...sarah/

Stroking is cool when you have +350 cubes to begin with, and stroking a little gets you to +400 cubes...but not when your motor is only 149cid.

- Brian

[JimmyMethod]

Yeah, you've got plenty of torque...what do you plan on doing with your engine?