KA24DE dream build

displacement of KA motor is 2.4l. 89mm bore/96mm stroke. To get this engine to rev/breathe better, either stroke needs to be decreased by a 10 or ideally 13mm, or bore needs to be increased by 7mm. Done the basic math, and boring out to 96mm puts overall displacement at about 2.6l at 9.5:1 compression. More displacement means you more power at all rpms, and if running boost, less boost would be required to develop relative horsepower.
the goal is 350hp reliable on pump gas. Is there enough "meat" on the block to bore out 7mm?

Another solution which addresses the issue of high compression is to destroke. Ideally, the engine should be "square" (bore = stroke) which would also allow the motor to rev higher. If the rods were shortened by 7mm making the dimensions square (89mm bore/stroke), total displacement is decreased to 2239cc (2.2 litres). Given that the known compression ratio of 9.5:1 stock, destroking by 7mm (a 7.3% net decrease in stroke) will result in an approximated new compression ratio of 8.73. it's impossible to calculate the exact value without knowing the dimensions of the cylinder head, head gasket, etc... But that's not too bad, taken into consideration that with a good port/polish job, taller head gasket, compression ratio will be further decreased. So we'll assume that net decrease in compression will be an approximate 8.5:1 compression, which is even closer to the magic number "7"
(7:1 compression ratio).

Further, at 150 hp stock, with a decrease in displacement of 200cc, we can assume that we will see an estimated drop in horsepower of 12.5 if power to displacement is roughly 16:1 (cm:hp). Given the lower compression ratio, net loss will likely be higher, but for arguments sake 137.5 hp out of a 2.2 l engine is not unrealistic.
that's 137.5 hp at 1 bar (14.7 psi, or earth's natural air pressure). running 15psi of boost we can assume that we'll see roughly a 100% increase in power, or 285hp. We can also assume that we'll lose around 15% of that power through friction/inefficiency, so 242.25 hp.
However, keep in mind that we are assuming that 242.25 hp is at the stock redline of 6500 rps (I think), so with a lightweight flywheel, crank balancing, port and polish, etc. plus the decreased stroke length we can assume that redline will be somewhat higher. At this point without a dynomometer and an actual car to pull numbers from this is all hypothetical.
But ussuming that redline is now 7500rpms (not as high as a Honda engine revs, but certainly respectable and completely realistic numbers from a DOHC 2.2l motor) if output from the motor were to be completely linear, output at 7500 rpms would be just shy of 280 hp.
So far, this all sounds to be fairly realistic, and with performance upgrades like a high volume air cleaner, free breathing exhaust (cats aren't necessary where I live, that's one less thing to worry about), an efficient turbo manifold, performance cams, ECU programming, a net gain of 50 more hp should not be unreasonable, putting total output at an estimated 330 hp, just 20 hp shy of my goal of 350hp.
Obviously at this level of output, huge changes must be made to the fueling system, (injectors, larger volume pump and a piggy back fuel management system are a MUST). I don't plan on shelling out the cash for forged internals, so just how far can the KA2(2)DE(T) be pushed on stock internals? how much more boost will it handle at the estimated compression of 8.5:1 without detonating or blowing head gaskets?
All that said, at 20psi estimated hp would be just over 360!!!

So from top to bottom, buildup of this engine would cost:
Engine - $250
T3/T4 Turbo kit - $750
Cams - $350
Intake - $75
Flywheel/clutch kit - $350
Shortened Rods - $900
Exhaust - $200
Fuel management - $300
Larger injectors - $200
ECU - $200
TOTAL-----------------$3575

so for less than 4 grand worth of parts, you could technically build a 350+ hp 240sx. The best part is KAs are cheap and readily available due to the large number of cars/trucks that these motors come in, and everyone else doing the SR swap. I plan to build this motor outside the car and then drop it into an S13. With overall weight reduction and some good suspension tuning, you could build a bad ass 12-11 second drag car or just a really fun to drive 240sx. The proof is in the numbers. given the car's good power to weight ratio, you could probably kill just about anything with this setup: corvettes and mustangs beware!

sure, but some of your prices are on the low side. depends on if your buying used stuff or not. or ebay crap.

and STOP TALKING ABOUT DESTROKING A MOTOR AND RAISING THE PISS OUT OF THE REDLINE. sorry. see other post. rod ratio is what limits redline. rod ratio and valvetrain. stroke has next to nothing to do with it.

ask questions and ill try and tell you all i know about motors.

On the contrary, it has been my experience that motors that have a larger stroke than bore ratio tend to resist revving. And while this may be only one factor in the grand scheme, destroking -- IN ADDITION TO grinding/balancing the crank, swapping in a lightweight flywheel, a good port and polish job on the head (which I did forget to mention in my pricing) and performance cams are certainly going to aid the motor in increasing redline. And as I said, it's not going to rev out to 11000rpms before redline like a B16, but a 7500rpm redline is NOT unrealistic for the aforementioned setup. Simply put shorter stroke = less friction = higher potential internal speed. If you would like to disagree I have several college text books and ASE certifications that say otherwise. Longer stroke = more friction = lower max RPM. Especially when stroke is a greater than value bore. (Directly from "Hot Rod U, UTI Glendale, AZ). Now while I'm not disagreeing with you, yes the valvetrain does have a lot to do with how an engine breathes, as a DOHC 16v engine, with the KA24DE the stroke to bore ratio plays a much larger role, as does the head, as does the crank and the flywheel.
A well ported/polished and balanced head, cams designed for turbo applications, a ground and balanced crank, shortened piston rods and a lightweight flywheel should be good for well over 1000 more potential RPM which is not an unreasonable number to expect. I didn't say it would redline at 12,000 rpms, I said 7500. My cavalier revs higher than that and it's bone stock...
But anyways, take it or leave it... I fully believe that given this setup the
KA24DE is more than capable of producing HP figures in the 300+ range. Plenty of people have for less money.

your missing the point like a broken pencil...

rod ratio is not stroke/bore ratio. stroke/bore ratio has nothing to do with piston speed, internal friction, or any of that stuff.
rod ratio is the ratio of rod length to stroke. it determines 2 very important things when trying to raise a redline: piston speed and rod angle. you can do very little to change the rod ratio in a given engine.

also when i said the valvetrain limits redline, i meant that the stock valvesprings and retainers are designed with the motor's stock redline in mind. raising the redline recklessly will at best cause valve float and at worst cause things to break.

you can make a 300hp+ KA-T with bolt ons and a headgasket no problem. no need to get into all that crap. but...
dont get me wrong here im not trying to shoot your idea down, just making sure you have everything in mind when attempting a big project like this. if you want to get into a technical discussion be my guest. ill put my real world experience + textbooks + ASE certifications against yours any day.

I'm sorry if I came off the wrong way. I'm not trying to get into a pissing match with you. Believe me, I know my shit when it comes to engines, but I've met PLENTY of mechanics without a single cert to their name who have forgotten more about engines, or even just one particular motor than I will ever know. With respect to you, you sound like a very intelligent person and at the very least you know a thing or two about Nissans.
If I intended to get into a flaming war I'd just spout off some stupid ass ignorant shit about "droppin' a RB26DETT into mah SIL80 and hittin' the NOS, yo!". Or worse yet, start another damn thread about how the SR is so much better than the truck motor. But that's not what I'm here to do. I appreciate your input. aside from my wife's old nissan hardbody with the SOHC ka motor, I haven't messed around with that engine. The most I ever did with that was change the spark plugs anyway.
So if you say the redline can't be increased then I believe you, but at the very least with the setup I proposed, it's going to hit redline a lot quicker than a stock 240 would.

i wasnt suggesting a pissing match or flame war, more of a friendly discussion. and hey, if you wanna try and re-engineer a motor, ill lend you all the help i can. seriously. id give you mad props if you pulled it off and made it last.
i went to a tech school too so i know half the stuff you learn is bullshit anyways, and they dont teach you the enginerd/physics side of it.

oh and im mature enough to admit when i miss the point.
i read up a little in one of my old books and it seems as though were both right.

heres a little summary.
A commonly known, but often forgotten fact is that the internal geometry of an engine can affect the engine's power delivery. Bore size, stroke and rod length all have a profound effect on an engine's power-delivery characteristics. An area of tuning just now being exploited by import engine builders is altering of the rod length to stroke ratio. The bigger the stroke-to-rod-length ratio (commonly referred to as the "rod ratio"), the more dwell time the piston has around TDC. This accomplishes several things. Since the piston is near TDC longer, the combustion event has a longer time to impinge upon the piston, allowing a better transfer of force to the piston, which slightly improves the engine's thermal efficiency. The longer dwell time also gives more time to fill the cylinders at bottom dead center on the intake stroke and more time to scavenge the cylinder during overlap. Since the piston is accelerated more gradually away from TDC, there is less mechanical stress on the crank, rods, pistons and cylinder walls. Reduced rod angularity at the point of highest cylinder pressure, also reduces mechanical stress, as the piston has less side load, and therefore rubs on the side of the bore less.

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Higher rod ratios result in less velocity in the intake ports; there is a lower demand for the ports to flow as well, as there is more time available to fill and scavenge the cylinder. Conversely, this can also mean stagnant flow at low rpm, which is not good for low-end power production, either.
To increase the stroke-to-rod-length ratio, some tuners are running a longer connecting rod, moving the piston pin up higher into the piston to allow this. Some engine builders are even running deck plates to raise the engine deck so a longer rod can be utilized. Some import engines have rod-length ratios as low as 1.49:1. 1.7:1 or better is considered good. The most highly developed four-stroke engines in the world, Formula One and motorcycle engines, often have stroke-to-rod- length ratios of more than 2:1. Many tuners of production engines are attempting to emulate this.
The bore-to-stroke ratio of an engine can also affect the engine's power characteristics. Over-square engines, ones that have a bigger bore than stroke, have lower piston speeds and less internal stress at high rpm due to lower inertial loads. There is also more time to fill the cylinders because of the lower piston speed. Engines with longer strokes and smaller bores, called under-square, have more internal stress due to faster piston acceleration and higher piston speeds. This accelerates wear and can induce seal-killing ring flutter.

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Under-square engines have higher torque and low-end power producing intake port velocities to ensure more complete cylinder filling at low rpm. Many import engines, most notably Hondas, are under-square.

Damn, u guys make me feel like I just walked into an advanced Latin Class...

Tuning a motor for peak performance and reliable power is a little more complicated than slapping on an APC cone filter and a "powered by DEEZ-NUTS" sticker. Many people fail to understand the geometry of how an engine works.

i wasnt suggesting a pissing match or flame war, more of a friendly discussion.

this makes me want to donate to the cancer society.

seriously dude, how much weed have you been smoking lately?

haha more than most people i guess.

Me and a friend where siting around and wondering if you could swap the head on a KA with a SR head anyone know anything about this?

no...and that has nothing to do with this thread, why did you post it here?

idiot.

plus i dont know why you would even want to. the SR head doesnt flow all that well. oh wait i guess im speaking to idiots. so any argument is moot. no it wont fit.