KA or SR20?

[COUGAR]

i've been looking into the engines for the 240 and soem say the KA is already a badmo engine with lots of tq and with a lil internal work can handle allot of boost. is this true or is the Sr20 kit better than just beefin up the insides and slappuin a turbo on it? (i was also told there are numerous SR20 kits out there so when i mention it i mean the average engine i guess)

[MingMing]

ka24de's have nice torque, the s14's have stronger internals than s13's as well, but still not as strong as the sr20det's
althou the ka24de's have more low end and a turbo would be great to balance out the top end while the sr20's dont hav as much low end,b ut the sr20 internals are stronger

[nguyen]

I don't think slapping on a turbo will change the characteristic of an engine. It will raise the power band. the KA power band is quite narrow. the KA also have longer stroke there for can't rev as freely as the sr would, the sr20det have a square bore/stroke ratio. what makes an engine fun to drive is not how much power it produce alone. an engine that make 100hp at 8000rpm is more fun to drive than an engine that make 150hp at 4500rpm. this is all opions of mine, but the decision is all yours

[IceTekGuy]

SR SR SR SR SR SR SR SR SR SR SR .......

did i mention that i like SR's, i got one almost completely done in my car, and i just drove my friends, OMG what a ride!!!!!!!!
220 hp STOCK
thats more than this '95' eagle talon i have to beat, although he is running  12.5's in a quarter, but still his motor comes STOCK with 195

SR SR SR SR SR SR SR SR SR SR !!!!!!!!!!!!!!!!!!

[ca18guy]

The cost's come out around the same. It's up to your personal preference, a smooth hi revving engine (sr) or a torquier engine (ka). Also if you have an older high mileage engine the a sr/ca would be best in my opinion. I'll attath this document I found, it seems a little biased for the KA but still a good read.


If you have a high miles on your engine, or if you have a SOHC, then maybe the SR swap is a better idea than turbo charging the KA. There is currently no manifold available for the SOHC KA.   Promises, promises!   But I still don't know of one for sale as of November 2000.   I think you will find that the kits are for the DOHC only.  

I believe that the total price to get 300hp out of the KA or the SR is very close, around $5000 including a big intercooler and some goodies. There are good sources of information and help for both projects, and parts for the SR are becoming much more available, just check the Parts Resources page!  The SR is factory tuned to run safely, at least until you raise the boost, and I have had excellent luck with 3 Nissan engines. The KA turbo project starts out with a displacement advantage which means a bigger turbo and more power at hand.


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Here are some thoughts from T. Y. Yap, he has a 97 KA24DET:

Here are my observations about the two camps: (oh boy, here we go again...hehehe) The long stroke nature of the KA give it it's distinguishing behavior or torque curve. The pattern for building for power is for increasing the stroke like the 2.2L stroker kit for the SR engine.

The standard SR can be built for speed. To get to that point, you need tight valve springs, valve lash kit and so on to prepare the head. More speed = more power.

However, power is a function of torque vs speed. There are two ways to get there. Let's look at an SR. To increase power, either raise the rpm or increase torque. So to this end, we have a stroker kit, and a high rpm valvetrain. Let's say, for some purpose, you cant get much more out of the valvetrain and is stuck at 7,500 rpm. You will have to increase the torque output to increase the power. Besides stroking, turbocharging is the other option for adding torque, which ultimately means more power.

So longer stroke is good for torque output, which together with turbocharging can accomodate much more power. For the KA's case, we already have the long stroke, so turbocharging is next. For the SR, besides turbo, stroking, high rpm is it.

But wait, there's more: it costs money to go for high rpm. Hardware life at these speeds are pretty short if any small mistake is made. Honda S2000 is the first mass production car to be able to figure out the material and be daily driven at 9000rpm redline (a major feat) at a cost of torque, but, on paper it still have the power, given the high rpm...

That brings us to another point. Have you driven a low rpm high torque engine vs a high rpm low torque engine? How's it feel? The low rpm high torque engine feels like a monster, and the high rpm low torque engine can be pretty weak without the right rpm. The high torque engine is much more streetable since it can move at any rpm vs the low torque engine. The high torque engine also seems like it's not even stressed a bit.

I have had an opportunity to sample both a SR20DET powered S14 and a KA24DET S14 (my own), let's just say, I love the response and torque of mine more. Yes, the SR was smoother in accel, but the torqueness of the KA is much funner and easier to boneheaded moves on the race track. Which one made more power? the SR. Which one cost less? Mine.

In the end, both will made a good upgrade to the anemic 240SX. Picking the right path is up to your pocket books and bragging rights... and ultimately which flavor you prefer: Vanilla or Rocky Road...


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More from T.Y. Yap off the FreshAlloy.com 240SX Discussion board:



Strengths and Weakness:

Facts:
KA24E/DE does not like to spin like the SR. It's ultimate redline will not be as high as the SR without modification to the engine. It does however uses an iron block capped with a solid crankshaft girdle instead of individual pieces. This provides a bottom end that is super strong with correct preparation.

The KA24DE features piston oil squirter for cooling of the pistons, much like those found in turbocharged engines. The piston however are the weak link in the KA24E and '91-'94 KA24DE. The '95-'98 KA24DE pistons are of stronger cast eutatic material that is stronger, but still not to the level of a forged piston. The weak links of all the pistons are the thin ring lands.

The KA24E does not come with a knock sensor, where as the KA24DE does. Because of this, Nissan lowered the compression ratio of the 1990 KA24E, making it the weakest performer of all the S13 KA.

Myth:
"The engine cannot be turbocharge because it wasn't from the factory."...that's like complaining that the grapes are sour because you couldn't get to the grapes.

Yes, there are some issues that needed to be addressed because the engine came NA from the factory. First of all, the compression ratio. Most would immediately say to drop in some 8.5:1 compression ratio forged slugs.

Yes, lower compression ratio is needed for a turbocharged engine, especially when you are pushing 2 bar (28psi) of boost where pump gas octane level could not handle the pressure before self detonation.

Turbo Porsches are notorious for their lag due to the low 8.0:1 compression ratio slugs and the high boost they run. Before the boost builds, the 8.0:1 compression ratio slugs compromises performance.

The Factory 9.5:1 (except '90, 9.0:1) by high boost standard is a little too high for boosting, but with proper fuel upgrades, air metering, tuning, it can run to 14psi of boost. (F-Max's S14 Turbokit Stage II). My personal example is running on 11psi of boost on the street using 92 octane pump gas. I even ran it during 120 F track temperature for 10 intense 15+minutes WOT track sessions without missing a beat.

What a turbocharged high compression ratio motor provides is good low end power with great top end power. Instead of depending on the Turbo to make the power, we are relying on the turbo to provide the supplimentary power up in the top end.

On the other hand, with a reasonable 8.5:1 compression ratio, some low end is lost but the top end and midrange could affor more boost resulting in more power.

Another item that needs to be changed is the Fuel system. Stock fuel injectors are only 270cc. That is barely enough to cover boost up to 5psi. Actually, it's outright dangerous at that level.

Power output:
Mine is estimated at ~300hp running a F-Max Stage II T3/T4 Hybrid Turbocharger kit. 1/4 mile times are 13.9 sec @ 103.3 mph. The ET is a little high given the trap speed. If I really tried a drag launch, I'm sure it would be brought down to 13.5 sec.

Details of the system:
525cc MSD (50lb) injectors, with fuel rail plus '93 Ford/Hitachi Mustang Cobra MAFS used with JWT modified ECU with stock internal. Exhaust is vented via A'PEXi's GT Spec exhaust which totally moved the power band way up high. I'm still short on midrange compared to if I had a smaller exhaust system like an N1 Dual. By installing the silencer, the midrange is back, but totally removed the turbo feeling where all the power is up high.

Exhaust Manifold:
Currently there are no commercially produced turbo manifold for the KA24E. It would need to be custom built much like the one on Joel's Turbo car.

As for the KA24DE, we are in a better situation. There are two known commercially available manifold. First one from RevHard Manufacturing, and the other from F-Max. Top End Performance also does have a turbo kit available, but not much information is known about them. The other is NSport. The NSport turbo kit used to be the Bell Engineering turbo kit which Bell sold the design and manufacturing rights. Last I heard, the manifold they use is the RevHard manifold.

RevHard Manifold:
The biggest advantage of the RevHard Manifold is that it's the only one that is cast iron. Cast iron construction cost more money, but it is much stronger for supporting the weight of the turbocharger and stuff. It is a runner style design. The manifold looks as if it can be mounted with either the turbo up top or below, but that is not entirely true. If the turbo is mounted on top, the exhaust ports will be misaligned and some porting work needs to be done to the manifold.

F-Max manifold:
This is a log style design where all the ports dump into a larger central manifold area. The manifold is constructed of cast weld el pieces. Ultimately it's not as strong as the cast iron construction, but it works as well. Also, for a simple turbocharge setup, log style manifolds work well, but for extreme power, a runner style manifold would be required.

Currently, I have the F-Max manifold on my car, and I have no complaints. I took mine to be ceramic coated and fitted with an EGT probe. I have a slight exhaust gas leak, but that's due to the copper gasket that I am using. Soon, the copper gasket will be removed and replaced with the factory gasket.
[update]: My manifold was the first prototype kit for the S14. Marty King of Import Car Garage pointed out that these early ones need to be modified to fix the leak. The mating surface needs to be cut from it's current one piece design into four separate pieces plus be machined for flatness. This will solve the exhaust gas leak that I have.

Characteristics:
All I have to say is Torque... Turbocharged KA has a bunch.

The engine used to be lazy to rev, but now with a turbo, the speedometer is behaving like a tachometer rising very quickly to the right.

The roughness is ...well... still there and inherent to the design of the engine (no balance shafts.)

Sound? ...well, that depends on the exhaust system... mine sounds with a deep mellow growl... I occasionally set other vehicle's alarm on a warning chirp and nothing else. It's not like before the turbo, where the sound will set anything with an alarm off.

My engine builds up steam at 4k rpm when boost peaks out. Below 4k, the engine still scoots pretty well. Above it and near redline, the engine is a monster (again due to my oversized exhaust.). I can accel hard in first gear until 5.5k rpm where all of a sudden the torque/power peaks and break the rear tire traction. Same in second gear. Note: this is with sticky Yokohama A520s and factory VLSD. I cannot imagine this with anything with a treadwear higher than 200. I'll be in trouble.

Cruising at 80mph is difficult due to the fact that any extra throttle opening immediately brings the car up to 100mph.

Commercially available parts:
Several Turbocharger kits are know to be existance for the KA24DE, and unfortunately none for the KA24E.

KA24E:
Nope, out of luck, only select few have gone and build their own SOHC KA monster. The first person I've heard of and met on line is Simon Kim in his 500hp+ SOHC monster. The other was formerly own by Ray, and now belongs to Joel who spend some time and effor to make it run properly.

KA24DE:
Top End Performance, NSport, XS Engineering, and F-Max are the only company that I know that makes turbo kits. Of these four, I only have experience with F-Max's products. SCC's 240SX project was built on the XS Engineering kit.

F-Max's kit features one very important item when it comes to Nissan tuning is the JWT tuned ECU. By doing this, you eliminate the dangerous addon devices that could be "changed" by unwanted hands. By leaving the tuning to the experts, and eliminate monkey business.

As for the others, I have no experience with them for me to comment on. Only extra I have to throw in here is regarding the XS engineering's wasteful piping routing. F-Max managed to get the piping up into the engine bay after the intercooler without cutting sheetmetal. It is routed through an opening between the frame rail and the suspension mounting point.




CLIFF NOTES:  There both better then stock!!!!

[nguyen]

when I reply to this topic, I alway like the SR20DET. All I want to say here is any fast 240sx I will respect, as long as you beat those rice Hondas.

[mike240]

I have to address the cost issue because it is bugging me...assume that you are going to have the shop do it:
now,  at unstable hybrids and heavythrottle a red top SR20DET(installed) with gauges and stock I/C, clutch etc. cost about 4K to 4500.  Now,  the XS engineering turbo kit for the KA24DE costs about $3300...just to buy.  Now you have to figure in the cost of:  if you have an 89 or 90(find a DOHC),  labor for installing the DOHC or at least the exhaust manifold and turbine(and for the shop to tune it).  Now assuming that labor would be comparable to the SR install(about $1200 or so) then that would bring it up to $4500,  and as mentioned earlier,  if you have an 89 or 90 and you would have to pay an extra 6 to 1200 dollars for the DOHC KA engine, THEN you would have to have your ECU reprogrammed for the KA which would be God knows how much.  All in all if you have an SOHC KA,  the SR would be more cost effective and if you do have a DOHC,  the SR swap would still cost a little less,  but to each his own.  And I live in Okinawa where SRs and CAs have a mere 3 digit price tag so the SR is definitely the way I'm going.  

[DSC]

I've got a couple questions. How much boost does the SR do stock, is it 7psi? How about a standard turbo kit for the ka, is it 7 also or only like 4 or something? How much HP would the KA be putting out with a bolt on kit running stock psi VS the sr's ~200hp running stock psi?

[tristarx]

You can't compare both becuase it's apple to orange since KA DET almost always use a bigger turbo like T3/T4 or T04/T3 while the SR is only equipped with a factory T25.

However, if you must compare apple to oranges:

Avg. KA24DET boosting 5-6psi ~ 220-230rwhp
Avg. S13 SR20DET with bolt ons @ 14psi ~ 230-240+rwhp

Tx.

Wayne
http://www.phase2motortrend.com

[S14KAT]

The SR runs on 7lbs. stock.  As for the KA at 7lbs, which is what Nsport advertises there stage one at, you'll get roughly 240rwhp.  At 7lbs for a stock SR, your getting 220hp.....which translates roughly to 185rwhp.  A difference of 55 horses.  Thats a pretty big difference.  T.Y.'s quote from Freshalloy brought up an intersting point as well.  95 and up 240, along with there stronger pistons, have a C/R of 9:6:1.  Thats not too bad, and like he said, with proper fuel management and an eye for accuracy, you can safely run the KA up to 14lbs. which I believe is right up there with the SR(15lbs.) as far as max boost on stock internals is concerned.  

Thanks ca18guy.....that was a very informative post, and best of all its not hearsay, its from a good scource.

[AceInHole]

heheh... someone should bring over his (TY's) chart for the 14.5 psi boost run.

But anyways, after upgrading the fuel system and turbo, the SR can get a bit over 15 psi.  Seen the charts for a 20psi SR20DE-T from a USDM SE-R.  The JDM SR20DET should be able to even get more.

The one with the 318.3rwhp @ 6,000rpm and 329ft-lb torque @ 4,300rpm?

It's more like 15psi with 91 octane pump gas too.

http://groups.yahoo.com/group/Team-NISMO-AZ/files/tyyap/97%20S14%20dyno.jpg

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from AceInHole on 5:10 pm on Jan. 15, 2002
heheh... someone should bring over his (TY's) chart for the 14.5 psi boost run.
</td></tr></table><span id='postcolor'>

[Freak Leash 240]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from 91 D21 beater on 3:39 pm on Jan. 22, 2002

The one with the 318.3rwhp @ 6,000rpm and 329ft-lb torque @ 4,300rpm?

It's more like 15psi with 91 octane pump gas too.

http://groups.yahoo.com/group/Team-NISMO-AZ/files/tyyap/97%20S14%20dyno.jpg

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from AceInHole on 5:10 pm on Jan. 15, 2002
heheh... someone should bring over his (TY's) chart for the 14.5 psi boost run.
</td></tr></table><span id='postcolor'></td></tr></table><span id='postcolor'>

I didn't know Mr. &quot;The Slow &amp; The Passive&quot; posted here, hhmmm <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>