Ok, this is pretty much a question for Big V. But I figured some of you others might want to chime in. So here goes... everybody knows that the 2.4 KA engine is able to make a lot of torque because of its [relatively] bigger displacement. Its peak torque occurs lower in the power band and the engine wasn't designed to rev high or create power higher up. Torque as I understand it, is a measure of the ability of the engine to move the car. Horsepower measures the same thing, but I can't remember the exact relationship (and conversion rate) between the two. I just know that high torque engines are usually used for moving heavy objects~ which leads me to my real question. If the 240 is supposed to be a "lightweight" sport compact, why go KA-T and high torque to power a "lightweight" vehicle? Yes I understand lighter weight, more power, go faster, but wouldn't a less torquey engine give smoother acceleration and throttle response?

 

i'll do my best here since i'm not Vinnie... the KA block isn't aluminum, so i can withstand a lot of abuse etc, in some situations (sr20de's) a higher compression engine + a lower boost turbo can make a fast car. I'm not sure how much of that low end power you lose when going ka-t, but any turbo vehicle is going to have an advantage in the upper rpms.

If your thinking of going NA, that's awesome, but imo, that's lots of time and money into something that may not give as good of results (hp wise)

I'd like to go ka-t because of the larger 2.4 works well with turbo, plus, for the begginning setup, the compression and low boost should make it pretty quick. also, it's not the sr20det that everyone else has either

Hope that helps, guys correct anything if i am wrong, that's just my $0.02

 

well I'm not an expert. But if the Ka has high torqe, then its good for accel at low rpms. turbos take power at low rpms and boost it at high, so if you got a turbo in a high torqe car, then you have low end, and high end provided by the turbo....... theorethically....... like I know.....:P

oh yeah, this should be moved to the tuboed KA fourum. This is for swaps only.... :P

 

Why KA? Because for the price of an SR motor and swap, you can rebuild a KA and make an absolute beast out of it.

 

no, ur missing my point. I was wondering why you'd want a high torque engine to power a lightweight vehicle. A Lotus Elise puts out 190 hp @ 7800 rpm and 138 ft lb of torque with a curb weight of 1,777 lbs. You could try putting in a C32B from a NSX that puts out 290 hp @ 7100 RPM's with peak torque of 224 ft-lbs @5500, but I would think that it would severely alter the driveability and handling characteristics of the car. I'm just wondering if a SR motor might be more appropriate for the 240 chassis on the basis that it was originally designed, produced, and sold with the SR motor... i m NOT alluding to any factors of cost into the discussion.

 

Chassis design has nothing to do with it, nor heritage or anything like that. People have made 500+ hp on KA motors in 240sxs with no chassis warpage or anything like that. The chassis is solid enough to handle large amounts of horsepower, probably beyond what any of us are capable of massaging out of a 4 cylinder.

The SR is good if you wanna follow the hype of the motor, and just stick something in because Sport Compact Car thinks the Ka is worthless, go for it. It's your money, so do what makes you happy.

I suggest you get the SR, in fact. I'll take your KA.

 

I beg to differ, chassis design has a lot to do with how a car handles. May be a better question for me to pose is how torque affects the handling of a car given that they have the same horsepower rating. The purpose of this thread was not to only compare the two motors. I'm asking how the different characteristics of the motor relate to the chassis and how the handling dynamics of the vehicle differ with each respective engine. I'm not planning on turboing my Ka or swapping engines anytime soon, I'm just asking around because I'm curious and I couldn't find this info anywhere. If you want my KA, ill sell it to you for the price of an SR... but be forewarned it has 180K miles on it and leaks oil in places you don't even know. But then again you might want to actually get a 240 to put it in first...

 

I like to think of it as... If you want low end torque buy a KA, If you want high rev's buy a CA, if you want something in the middle go SR. They're all capable, proven engines and I have no idea why people want to complicate it any more than that. Chassis dynamics are so tunable I don't even think it should be any sort of factor for a street car. Now if you're discussing price, that depends on your budget, goals, and ebay.

 

Well, if you wanna be stupid.

As for my 240, picking up a new one next week. Had to sell my 90 coupe for a move to Denver from New Hampshire. You should listen to what I'm With Stupid said.

 

Thanks, that's exactly the info I was looking for. I was just wondering if the higher torque of a KA-T would change the chassis/handling dynamics of a 240 when compared to a SR powered 240... but I guess not enough to matter.

 

torque is fun though, high horse power gives you a highway monster, but without torque you couldn't tow a cheese sandwich

 

or do much of anything, torque is the biproduct of the rotating mass of the engine, without it, your car would be very slow. like a high revving, no torque honda

 

Well I'll try to simplify this the best way possible. In doing the conversion to get HP, you have to calculate the byproduct of torque first, and then there is a division process that gives you your HP rating.
Here is the thing about torque though, it will take less HP to get you going faster down the track on acceleration. For an example look at this at this geocities dyno and 1/4mile time.
http://www.geocities.com/wssnider/240sxDYNO.html
If you pay attention to the 1/4 mile time this 240sx makes less HP than the RSX types s, but beats its 1/4 mile time. HP isn't always a key factor to acceleration. The engine is one source of power, but you also need to drive that power with a drive train as well, transmission gearing is vitaly important speed acceleration.
As far as rev is concerned the KA is limited to peek power at about 5680RPM ( I said PEEK POWER, NOT REDLINE which is about 7130RPM), but this is only due to it's cam specs, and adjustment in the TTP. The KA isn't advanced enough nore does it have an aggressive enough cam spec to really make power any higher. Mostly due to poor programming of the USDM ecu, it isn't that efficient.
Now why KA-T? Once you add applicable bolt ons like a turbo for forced induction you are manipulating the power band. This doesn't mean that you are just making torque. But you can also make big numbers in HP. For example a KADET that makes more HP than Torque. This was done through the advancement of the cams and an ECU reprogram, as you can see the KA is what you make of it, it's how you chose to build it. Bore and stroke doesn't mean that the engine is "JUST LIMITED" to early torque numbers.

Here is another example of manipulating HP and torque numbers with a turbo, where it makes more torque than HP. (Greddy turbo kit, ALL stock features with no advancements and a slight reprogram of the ecu).


So now lets apply the transmission gearing ratios, which the SR and the KA both use what is called the werner synchros system, the only advantage the sr has in stock is the 5th gear .838 gear ratio (the nismo 5th), other than that the transmission gearing is the same.
Now lets adapt the engine to transmission.
The KA for instance will make it's power sooner in the late 5000RPM's this means you are shifting sooner with that power that you are limited too. Lets say that the SR makes the same power but it has to travel up the power band to the mid 7000RPMS, it will take the sr longer in that gear to make power and acceleration, unlike the KA which has achieved it early.
The KA is overall much more aggresive and quicker on the throttle in the lower RPM.
I've learned not to be too opinionated in the debate of KA over sr. But for my own personal prefrence I like to spank the compition early (refering to shifting points and power made), hopefully you see where I am getting at.

 

SR20DET and KA have the same 5th, you're thinking of the SR20DE.

 

Thanks for catching me on that one, but the CAdet comes with the .838. Sometimes I get confused looking at the synchros gear boxs, there all pretty much the same.