Buying built KA24DE, please advise - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Lurkable · 12-31-2005, 05:55 PM

I'm about to buy a new KA24DE. I've considered buying just a rebuilt stock engine, as well as possibly a boost-ready crate motor. I'm starting to lean toward the upgraded crate motor such as HRT advertises, especially since stock rebuilt engines are nearly $2000 and, even if I don't turbo the motor, the boost-ready KA will undoubtedly add nicely to the car's resale value in the future.

I have a few questions hopefully you guys can help me with. Wether I get a stock rebuilt or upgraded rebuilt engine, I won't be turboing it for a while, if at all

. If I buy an upgraded one, I can see myself driving the car for up to a year still being n/a.

My biggest concern for an upgraded motor is going to be compression ratio. Stock compression for the KA is 9.5:1 I believe. How much would 9 or 8.5 pistons hurt performance on an n/a KA? I basically don't understand anything about how compression ratio, piston size/shape, and cylinder volume all relate so feel free to refer me to something that explains all this

.

Also, if I do eventually decide to turbo the motor, I won't want to go over 300 whp. In fact, maybe not even over ~250 whp, I'd probably go with a simple reliable 370cc/AFC/(possible tuned ecu) setup - but I'll take the forged pistons and shotpeened rods for solid reliability. So I'm just trying to decide specifically what upgrades to request from whoever builds my engine. (Mainly pertaining to piston compression ratio and cylinder size). I'm not sure that overboring the cylinders is even necessary for a 200-300 whp KA, but by all means, please explain if/why it is.

Thanks for any information/advice you guys have!

smithers584 · 01-01-2006, 05:02 PM

ill try to make this simple as possible. you need to know what you want to do with the motor before you build it. higher compression means more power w/ a n/a motor. lower compression for a boosted car is better do to the forced induction, more volume coming from the turbo. 8.5 to 1 would be rather sluggish w/o a turbo, but is ideal for boosting. either stay n/a and raise your compression or go boosted and lower your compression. high volume in a small cylinder means high compression. the same amount of volume in a bigger cylinder has lower compression. if you dont know what you want i wouldnt do anything until you do.

theicecreamdan · 01-01-2006, 10:25 PM

higher compression = more power turbo as well, but the added risk of blowing up.

12-31-2005, 05:55 PM	#1
Lurkable Zilvia Member Join Date: May 2004 Location: SF Bay Area Age: 39 Posts: 171 Trader Rating: (0) Feedback Score: 0 reviews	Buying built KA24DE, please advise I'm about to buy a new KA24DE. I've considered buying just a rebuilt stock engine, as well as possibly a boost-ready crate motor. I'm starting to lean toward the upgraded crate motor such as HRT advertises, especially since stock rebuilt engines are nearly $2000 and, even if I don't turbo the motor, the boost-ready KA will undoubtedly add nicely to the car's resale value in the future. I have a few questions hopefully you guys can help me with. Wether I get a stock rebuilt or upgraded rebuilt engine, I won't be turboing it for a while, if at all . If I buy an upgraded one, I can see myself driving the car for up to a year still being n/a. My biggest concern for an upgraded motor is going to be compression ratio. Stock compression for the KA is 9.5:1 I believe. How much would 9 or 8.5 pistons hurt performance on an n/a KA? I basically don't understand anything about how compression ratio, piston size/shape, and cylinder volume all relate so feel free to refer me to something that explains all this . Also, if I do eventually decide to turbo the motor, I won't want to go over 300 whp. In fact, maybe not even over ~250 whp, I'd probably go with a simple reliable 370cc/AFC/(possible tuned ecu) setup - but I'll take the forged pistons and shotpeened rods for solid reliability. So I'm just trying to decide specifically what upgrades to request from whoever builds my engine. (Mainly pertaining to piston compression ratio and cylinder size). I'm not sure that overboring the cylinders is even necessary for a 200-300 whp KA, but by all means, please explain if/why it is. Thanks for any information/advice you guys have! __________________ Rim: n. The circular outer part of a wheel, furthest from the axle. Rim: n. A circular metal structure around which a wheel tire is fitted. Wheel: n. A solid disk or a rigid circular ring connected by spokes to a hub, designed to turn around an axle passed through the center.

01-01-2006, 05:02 PM	#2
smithers584 Zilvia Junkie Join Date: Dec 2004 Location: sc Posts: 416 Trader Rating: (0) Feedback Score: 0 reviews	ill try to make this simple as possible. you need to know what you want to do with the motor before you build it. higher compression means more power w/ a n/a motor. lower compression for a boosted car is better do to the forced induction, more volume coming from the turbo. 8.5 to 1 would be rather sluggish w/o a turbo, but is ideal for boosting. either stay n/a and raise your compression or go boosted and lower your compression. high volume in a small cylinder means high compression. the same amount of volume in a bigger cylinder has lower compression. if you dont know what you want i wouldnt do anything until you do.