Question1998-2001 2.4 LTR Altima VS 2002-2005 2.5 LTR. Differences Anyone Know?

[drb930]

What did they do to get the displacement increase? And 20 more HP?Bored, stroked, is the crank different, cams?Does it have Variable valve timing?

Will any of this stuff benefit the KA24DE in our 240SX's?

[nismo96ka]

yea it's variable valve timed. but the motor is a whole animal. so if you're thinkin bout swapping the 2.5 parts to your 2.4 the best thing i can say is fuhgetboutit. the 2.5 has it's problems by the way. just ask any spec-v or altima owner who's had there's suck the screw from the throttle plate through the motor. in the 10 months i was at the nissan dealership we had at least 25 of those. my preference : KA24DE

[bleufiend]

The motor in the O2 plus is the QR25DE that you are referring too. None of the parts from it are interchangable to your KA24DE.

The motor is a complete redesign and totally different from the KA, hell they even cast the block differently(QR=diecast block versus the KA being sandcast). Oh and if you wanted to know I believe the bore is like high 80's low 90's in the mm, the stroke is 100mm(limits our redline to 6200rpm) and our valve timing is called CVTC (continuously valve timing control) and is active throughout the rev range.

With the diecasting they were able to make a more precise mold of the engine and save metal in the process which means its lighter but the down fall of this is that it leaves the engine in a open deck design which is not the best when it comes to turboing your car. KA24DE would be better for turbo.

As far as the screw issue goes that nismo96ka discussed. Those are the butterflies, in the 02-04 models they liked to back out of the plates and get sucked thru the engine so most owners took apart the intake manifold and loctite them to prevent this.

Id say stick with your KA and build it for your car or just drop an SR since its a 240 your talking about.

[altimecca]

that butterfly problem bleufiend taked about was pretty bad, nissan actually had a recall to fix this problem. on another forum, way, way, back in the day, i read that the KA was made from an iron block, and the QR is aluminum.

[l31nismo]

yea it's variable valve timed. but the motor is a whole animal. so if you're thinkin bout swapping the 2.5 parts to your 2.4 the best thing i can say is fuhgetboutit. the 2.5 has it's problems by the way. just ask any spec-v or altima owner who's had there's suck the screw from the throttle plate through the motor. in the 10 months i was at the nissan dealership we had at least 25 of those. my preference : KA24DE

Not to mention the ones I had to put motors in for that problem and the Cat recall. THat was bad. But The 2.5 is a decent motor. The newer ones have fixed those problems but who knows what will happen next.

And by the way, There is no way for you to swap internals. You might as well just by the SR20DET.