FJ vs. KA

[deadpirate]

Moderator edit: This was split from a tech question thread about FJ valve cover gaskets, and had no real business in a tech question thread. The issue is around the FJ that came factory in Arro's 1985 Silvia RS-X.

FJ NA carb'd? Don't you already have a KA? Why bother? At least with the KA you can run to the nearest store and get literally everything

[seishuku]

It's an actual JDM 85 RS-X, it came with an FJ.

[Arro]

That, and the fact that in every way, an FJ is superior to a KA by leaps and bounds.

[VG33ERGazelle?]

FJ > KA

[deadpirate]

Aside from it making the exact same power, I'm sure it will be better by leaps and bounds when it dies on the road and you're forced to wait the next month for maintenance parts to come in.

Engineered better than a KA? Absolutely.

An obsolete engine stateside? Absolutely.

All it can ever do at this point is look cool and get you brownie points. It'd be a pretty neat door stop too

HOWEVER THAT WAS NOT THE POINT OF MY FIRST POST, I was simply implying that you'll be making KA power with a carb'd FJ.

[Arro]

You're like the newest jeffwins on this forum, bro

DO YOUR HOMEWORK. The ports on both NA and turbo FJ heads are HUGE, and as crossflow heads go, are nearly straight, with little bending of the airpath in and out of the combustion chamber (this is why the FJ head is so WIDE). This is especially good for NA.

The KA24DE heads have a sharp downturn in the airflow path, which is why the twincam heads are so narrow compared to the SR or the CA18DET. This makes them torquey but restricts horsepower. This is also why when you want to make serious power with a KA24DE, you BOOST it. Even then, a boosted FJ will make more power using the same spec turbo and other associated hardware that you could put on a KA24DE. AIRFLOW is key.

And this car CAME with the engine. It's an authentic Silvia RS-X. Would you have me remove the FJ it came with and put in a KA? I would wager that 90% or better of people here would find that notion ridiculous.

And as far as leaving me stranded, anything that would do that to the FJ would do the same to the KA, only sooner. The FJ is in all technical specs (CFM, block strength, valvetrain strenth, rod strength, and on and on and on) stronger and more efficient at making power. SO... it will make the same power as a KA with LESS stress on the engine, THEREFORE making it a HELL of a lot more reliable in the end. It's similar in design to an L-series engine, which if you knew anything about vintage Nissan engines, you would know that those L-series engines are just short of bulletproof.

Anything that would require me to be down for periods of time in order to obtain parts would require labor time, too, and the KA would require the same labor (or more?). I can get parts. Will it cost me more? Sure. But the extra cost and shipping time is the trade-off for an engine with superior performance specs, superior reliability, and  (OMG this is the BIG reason) the ORIGINAL engine that came with this RARE car.

And the FJ is no more obsolete than the KA24DE. In fact, you can run an FJ on SR20 electronics, which are essentially the same as the KA24DE electronics. But with the advantages that come with the FJ longblock.

You wanna claim I'm trying to win "brownie" points with my authentic JDM S12, go for it. I know there are dozens of people on here who would love to own this car.

BUT... you want us to be aware of your FIRST POST, which is to say that the FJ carbed will make what an KA24DE does.

I have news for you, this engine it sits (only timed properly) would probably make almost double that. The previous owner was hoping for 300+ NA. If you understood both the tuneability of Weber DCOE style carbs, and the airflow properties of the FJ head, you'd just keep quiet in this thread and save face.

In no way does the KA twincam head compare to the FJ head. Nor does the KA24DE intake manifold have the same flow capacity of twin Webers.

Actually, someone took and set up a KA24DE with ITB's and Megasquirt to run it all, and large cams, ported head, etc etc etc... in an attempt to make an NA beast... and it didn't make a whole lot of power over EFI.

Really tho, I think you've been acting like something of an ass on this forum recently, but I only bothered to state all of the above for those newer peeps who might find it interesting. Since I think you're one of those guys (i.e. jeffwins) who will just argue rather than face facts or do any real research.

I was probably the first guy here to even bother to research this engine. I don't know everything about it, but I know enough to know you don't know much at all.

[deadpirate]

My logic and judgement follows that of ease, accessibility and fun/dollar ratio. You honestly don't have to pour every single bit of information you've learned off of wikipedia and google search, you talk as if you've applied any of this information in the real world.

I also find it hard to believe that you don't understand what I had meant although I had already explained it. I know you already have a KA car, why would anyone tell you to have two?

I've also had enough triple weber experience with many an L series, mind you, and it really would be the day to see that power from an FJ. But you're talking about potential possibilities here, for example a single cam ka making 300+hp carbureted is already standard practice for places such as rebello.

However, YOU, doing anything remotely similar, really would be quite the day. And I await your progress, rather than read your about these "possibilities". You can talk as long as you want, man, people read your posts like they read jeffwins posts. They're skimmed, if that.

[Arro]

Ass.

I didn't build this engine. Another guy did. And tuned it. And tested it. It's a proven fact. I'm going to consider further comments like yours imflammatory and not really contributing to anything. Just trolling. The last troll I banned WAS actually Jeff.

So let me give you not advice, but public directive: Show some respect. Or shut up. Because I'll start by collecting your troll posts. I'll finish by getting the team approval to boot you out.

You're just being an asshole in here. To me a number of months ago. Then to Sam. Now to me again. Big mistake. Take my directive and take it serious.




On-topic, I cleaned up the OEM cams and those will be going back in with the OEM FJ20 sprockets. Once the carbs are better tuned I can throw in the FJ24 cams and sprockets. Jsut going to make things easier. This is why I'm locating a valve cover gasket for a better price.

[Xano]

And to me about some transmissions in the past...I dont really see a reason for you to be here personally, and I can garuntee that if he says he will ban you, he will.  I dont give a fuck if you care whether you are banned from this site or not, I'm just letting you know, that it will happen.  I can also garuntee that if I notice a pattern of dickheadedness, others notice it too, not counting admins.  So far nearly every tech response you've given has been refuted, so I'd say its a good time to "shut up and sit down" for you.

[EightySix200SX]

Aside from it making the exact same power, I'm sure it will be better by leaps and bounds when it dies on the road and you're forced to wait the next month for maintenance parts to come in.

Engineered better than a KA? Absolutely.

An obsolete engine stateside? Absolutely.

agreed. fj is a hassle stateside.... where it is domestic if i lived there like jp or aus id rock one hella quick but were not in aus or jp. imo vg30e's and ka24de's will always have parts avail nissan nor aftermarket will EVER and i repeat EVER discontinue repacment parts for any of these motors since ka24's were avail from 88-04 and vg30/33's from 85-04

wow! this thread went to shit fairly quickly....

arro out of ease of parts and you all will prolly all hate me for this id paint up the fj real pretty and use it as a coffee table and, i would swap a boosted ka in for ease and reliability not to mention cost effectiveness. im not knocking the fj20 by any means because it is a godly motor forced inducted and built and puts down some amazing power figures. as much as id like an fj id hate to track it and fuck something up. now if i track a ka swapped car hah autozone, nissan, pepboys always carry ka24de/e shit. all in all rhd or not its still an s12 and swapping the fj wont depreciate its value, i mean these arent exactly barrett jackson material anyway.......

[Drft-s12]

You guys think we cant get shit off the shelf.....there are many things we can get that crossovers but like Arro was saying whats going to break???? This motor is a fucking monster and its nearly impossible to break, i know ive drivin my FJ around and beat the shit out of it.....Yeah maybe we cant get much aftermarket shit but what more does it need...a bigger turbo, standalone, front mount, etc....and that shit is beast..

All i can say is im not afraid to go past 8000 rpm in a FJ.....how many ppl can say that without breaking a sweat in a KA or any other swap.....

[EightySix200SX]

I didn't say that. I said it would be a task to get shit and I also said I wouldn't do it as in me personally. I'm not attacking fj motors guys sheesh.

Edit: I never once said why any of YOU should not stick with fj motors I simply stated why I wouldn't. If u have an fj kool if ur ka or vg cool, slow sohc ca cool, in the end its still a fucking s12 regardless. And yea if I owned a genuine fj car id swap it. I personally wouldn't wanna deal with it. If you think that's dumb ur intitled to YOUR opinion.

[Jay]

My logic and judgement follows that of ease, accessibility and fun/dollar ratio. You honestly don't have to pour every single bit of information you've learned off of wikipedia and google search, you talk as if you've applied any of this information in the real world.

I've also had enough triple weber experience with many an L series, mind you, and it really would be the day to see that power from an FJ. But you're talking about potential possibilities here, for example a single cam ka making 300+hp carbureted is already standard practice for places such as rebello.

1st off, Show us this 300HP Sohc NA KA. I have never seen, or heard of a street car anywhere near that...
2nd off, How much is this supposed 300HP Sohc NA KA
3rd off, I'm with Ben and Arro on this one. All I will say about that here

Keeping a rare car, that rare variant, Is the cost of all things when owning 1 of 2 in the U.S.
/arguments

Nothing more needs to be said. This is a TECH discussion, not a crapshoot

[Arro]

arro out of ease of parts and you all will prolly all hate me for this id paint up the fj real pretty and use it as a coffee table...

And that would be one awesome, epic coffee table

Justin I feel no disrespect coming from you on this so it's cool bro... and yes, finding engine components for the KA is leaps and bounds easier and quicker, but Drft-s12 is right... it's not impossible for the FJ, either. I just ordered my valve cover gasket set, should be here in a week or so. Yes, it's coming from Oz, but anyone who bothers to own and maintain an FJ usually has a backup car, anyways

And he's also right that anything serious would put down a KA for awhile, too, for repairs... but the real thing to note here is that in NA form, the KA is far inferior to the FJ. The FJ is good boosted, but it's also good without. The FJ24 rally engine was carbed with two Weber carbs too, and the FJ heads were designed initially with that in mind. That's why Grant added them to the FJ20E (and removed the EFI stuffs).

That said, I love my KA24DE, too. It's a great engine. With some work it can make lots of power, but I also know it takes less work to make more power with an FJ.

Anyways, the gaskets are on the way. Another week or so I'll post updates.

[mod_mastaz]

This argument sounds very familiar. Someone was dead set my motor doesn't have parts(oem or aftermarket) available stateside and that it was proned to numerious problems. Now that very same person is justifying the use of a MUCH older engine with parts that actually aren't readily available at any part store with upkeep costs 4x as much as mine. On paper, the FJ sounds great; in reality, I'd hate to upkeep one. Anyway, looking forward to that 300hp CARB'd NA FJ.

[Arro]

You know what Hung I expect more from you insofar as using your noggin, 1. because I know you personally, and you're smart, and 2. because you know the story behind the car in question.

I didn't decide "oh gee, I'm gonna get an FJ!" It CAME with the freakin' car, man! I asked this earlier in this thread, but obviously I should state it again... what would you have me do, pluck the FJ out of this authentic Silvia, and put in a KA24DE? Or CA18DET? Really now. Is that what you're saying? I mean you make it sound like I said, "hmmmm... let's get an S12 and get an FJ and put them together."

And that's unfair of you. It's *almost* like you want to criticize me for something (anything? hmm this is all not your style, bro), but....? Even Matt (seishuku) said what I did -- this engine CAME with the car. To remove this engine from this car would be a CRIME if you ask me or I would imagine most others here (who know what the fuck it actually is).

Now, with that said, I will address two other things, but just once more. Because if I have to state it again, I'll know who wasn't actually paying attention

For one thing, I DO like the novelty of the FJ20 engines. I do also realize it's harder to get components for them (similar to a CA18DET), which is where the KA24DE is better off. BUT... for me, the FJ represents the BEST purist-correct engine (meaning no SR, no KA) that ever came in an S12. I say "best" as a matter of opinion, but IN my opinion, while the CA18DET is more advanced, I believe the FJ is superior in terms of both the strength of the internals, and the flow design of the head. I could care less about independent coil setup, or trick timing advance. But again, that is preference and opinion. But because of that opinion, if I wanted to go with what I felt was the "ultimate" PURIST-correct engine for an S12, IT WOULD BE THE FJ. Others might say it would be the CA18DET. Again, it comes down to opinion.

WHAT IS MORE, the FJ20 *IS* actually superior to the CA18DE or the KA24DE in terms of natural aspiration potential. The head is designed in such a way as to optimize aspiration, and was originally intended for a dual carburetion system, and the only major difference between the FJ24 and the EFI FJ20E/ET is mostly in the bottom end.

While the CA18DE isn't a bad NA engine, it doesn't hold a candle to the nearly straight-through intake/exhaust airpath of the FJ head. The air almost "skips" off of the combustion chamber. And the KA24DE's sharp airpath bends are a terrible NA design for higher horsepower goals.

Really, there is no trick to getting loads of power from an NA FJ. It's pretty straightforward. Open the intake system wide as you can go (i.e. high-flow carbs, such as Weber DCOE's), give it the right fuel to match the new air volume, and plenty of spark. Advance the timing, use a super lumpy cam. Thinner cometic head gasket for further compression. Will that net you 300hp NA? Maybe.... maybe not. But it'll get you DAMN close at the very least, and without the delays of boost (giving you amazing response).

IN contrast, the EFI setups in both the CA18DE and KA24DE are only part of the limiting factors of NA expectations. Even with ITB's and stand-alone, neither of those engines will hold a candle to the airflow capacity of the FJ (due to port flow limitations, port geometry designed more for torque than horsepower). Those who have tried have hit a pretty solid performance wall, which is why both the KA24DE and the CA18DET are considered best boosted... because boost overcomes these limitations.

Although once you consider the FJ20ET[/u], it still benefits from the superior head design and with the added benefit of stupid-strong internals, giving it a double edge over the other two. And meaning that making power is easier and safer than the other two engines.

Despite it's difficulty in obtaining parts

So three things here:

1. This engine came with my car, and I'd be stupid to even consider removing it. So I might as well work with it, and own something rare, unusual, and yet still powerful.

2. The FJ is an important part of the S12 legacy, and arguably the meanest engine Nissan put in an S12 from the factory.

3. The FJ is actually a damn good performance platform in terms of tuning potential, despite the difficulty/hassle of obtaining parts. And I don't need first-hand experience to know this, since the potential of the FJ20 is so well documented on a few sites (including AUS12, FJ20.com, and of course, Club-S12... if one bothers to look at old threads).

If that doesn't make it clear enough, I don't know what will.

[WankelMonkey]

Another thing to consider that I imagine most people are overlooking. Jason doesn't plan to drive the crap out of this car. It's more of a museum piece or a garage queen if you will that will only be turned over every once in a while to take it to car shows.

Is it practical to restore a Duesenberg? No, but people still do so and enjoy the challenge. This is no different, Jason is merely investing the preservation of a piece of Nissan history. For the most part, aside from the Weber carbs, this is a numbers matching car. Anyone who restores classic cars knows the relevance of what that means.

my 2 cents

[mod_mastaz]

Whoa there buddy, I never said anything about removing anything. I just said the FJ would be a hassle to upkeep. I also did not even start the argument on which motor is superior. I honestly don't care. With enough money, one could build anything.

You want my 2 cents? Properly put the motor back together, ditch the carbs and go EFI and get it tuned. Carbs work, but EFI is where it's at, especially when you want to squeeze every last ounce of power out of that thing.

[VEGIE]

It always makes me laugh when people who have never owned/driven an FJ powered car like to bag them...

ive owned/driven a number of A series, L series, CA series, RB series, VQ series SR and FJ series cars.

ive owned 7 FJ's now, and would own another anyday over a/another SR/KA/CA.
i live i country flooded with imports from Japan, but even so FJ cars are rare.

Sure, they are old. but they are no more obselete than the chassis they are fitted to.
Mine is 27 years old in my US12 RS-X.

they were never a high production engine,which is why they are desirable. but as a result parts are less obtainable too. i have heard it rumoured that there was only 2500 FJ powered cars built, but cant confirm that.

but hey, its not everyday you need to go down the road to buy a gasket set or simular is it!

you pull down an SR, CA, and FJ side by side, and you'll see why they have such a reputation. the room for potential from factory without modifying any internals is huge.

there major downfall is the primitive EFI system. but so many aftermarket EFI systems make it easy to overcome.

[deadpirate]

Wait, who the fuck is comparing an FJ vs KA? It scares me to death that no one understands what I'm talking about. Is this really all club-s12 can do? Turn valid points of convenience, cool factor, and common sense into a VS thread?

versus threads are so 2006

^^
It always makes me laugh when no one understands a god damn thing and turns it into a showcase of their own "supposed" egotistical knowledge.