what makes the E a better motor than the DE?

[float_6969]

The compression was lowered for emmission changes that were going to take effect in '90. They lowered the CR and then stuck a modified computer in it to keep the HP the same. I'll bet if you took early 89 pistons and put them in a late 89-90 motor, you'd get a decent power jump. The latter motor has better computer programming. As for wich to purchase, it depends. If you want to do a motor swap, get a cheap old SOHC 89-90 and beat it up till it dies. (my philosophy) If you want to build an all motor KA then I'd get a nice DE and start with that.

[S13Ka24e]

The reason why compression was lowered, in my opinion, was to compensate for the motor not having a knock sensor. If they did incorporate a knock sensor, compression could remain high and the ecu would adjust to any knocking conditions.

I thought the ka24e had a knock sensor....?

[C-Kwik]

Realistically, the DE will breath better. 4 valves make better use of the space in the head then 3 valves. In other words, more of the top of the combustion chamber is comprised of the valve. This allows more flow and in turn better breathing. Since an engine is preety much a glorified air pump, the better it breathes, the more power it makes.

I think the rumor of the E being more capable is more of an urban legend derived from the fact that NASPORT GT race KA's use the KA24E. But this is really because of the rules in the NASPORT Series. They are not allowed to use the DE mtors and they are required to use Carbs. But I haven't seen any mechanical element to the E that makes it any more capable than the DE.

[JNM240]

Well, I believe that if you were to get the NissanMotorsport exhaust valves (40mm) custom installed into your SOHC then the difference between 12 valves and 16 valves would become moot. They are both great engines. I am of the mind that neither one is better or worse than the other. I just feel that you make do with what you got. I got a KA24E. So i built it. And i built it good

[C-Kwik]

Consider that the DE exhaust valves are 31.25mm. In comparing the total area, 1 40 mm valve would yield a 1256 mm area while two 31.25mm valves yield 1533.2 mm area. Big difference if you ask me. I don't question the integrity of either engine, but better breathing motors will usually have more power.

[SSS]

I heard the DE head is a fair bit heavier than the E head....

[Daves240]

My experience... I have a 12/88 production date '89. I rebuilt my motor w/ the 9.1:1 pistons and I noticed a decent gain. When I put my motor in I installed a N1 single. Even w/ the addition of the N1 I noticed more torque. A friend and I hooked up a street dyno (uses ignition pulse to figure power) and my torque curve was VERY flat, it came on strong and stayed strong. It wasn't until after 4k for the DOHC to pass me. In the defense of the DOHC he had a stock exhaust. After driving a low and high compression SOHC and a '92 DOHC. I can say my high compression SOHC pulls harder than the DOHC down low, but after 4k the DOHC pulls REALLY hard. My SOHC would win to 0-45, tie in a 0-60 and lose bad in 0-100 against my friend's DOHC.

I have a pic for those interested...161lbs/ft@2500rpm

David J.'89 240sx

[Stock-S13]

ok what is considered late and early production? are we going off the 4 month basis as if Jan-apr is early and March-Jul is mid and so on? i have an 11/88 so iam leaning that i have a late model.. i guess what my question is when did these cars go out into the market?

edgar

[Daves240]

The KA24E s13 started production in 7/88 and ended in 7/90. The 7/88 through 10/88 models had the higher compression 9.1:1 pistons. The 11/88 through end of SOHC production were the lower 8.6:1. The KA24DE s13 was from 7/90 through 10/93. Then the s14 DE from 2/94 through end of production.

David J.'89 240sx

[Sleeper s13]

I have been reading the post and have a 92 DOHC and was looking to boost the compresion as a cheep means of hp gain. Would the 89 or 90 SOHC pistons be better to swap into my engine, and does this mean the rods and the heads or just the heads. Do the cranks have similar journeys?

[JNM240]

All you would replace is the pistons. You keep your crank, rods, head, ect.

[89S13 Drifter]

My friend who is a neon guy told me as far as with their cars sohc and dohc that the sohc is a faster accelerating car than the dohc. But the dohc can go faster in the long run. I would assume it is most likely the same theory for all cars. In closeing I would argue that if you had a E and a DE of the same horsepower and same weight, the E would win the 1/4 mile, but the DE would win in say a road race.

[C-Kwik]

My friend who is a neon guy told me as far as with their cars sohc and dohc that the sohc is a faster accelerating car than the dohc. But the dohc can go faster in the long run. I would assume it is most likely the same theory for all cars. In closeing I would argue that if you had a E and a DE of the same horsepower and same weight, the E would win the 1/4 mile, but the DE would win in say a road race.

Depends on the actual output of each motor. You will find variances in power for the same motor out of the factory. But theoretically, if you had a DOHC and SOHC motor, and they made the exact same power(same torque curve), then the two cars would run exactly the same regardless of how many cams it had. In reality, the same motor manufactured at the same plant as another can actually have different outputs. It should be close, but occassionally you'll get one with abnormally high or low output. That being said, to compare a Neon motor's charatceristics to a KA is comparing apples to oranges. There are too many other factors to consider. VE is one of the most important factors in how an engine performs. Generally, motors with 4 valves per cylinder make better use of the space in the head and have a higher VE, particularly at higher flowrates. This generally equates to more torque.

[ADAMHU]

the DE head is much heavier than the E, it is far more complex..and porting the E head is much easier than the DE, after porting both of them, the E head IMO is the better head ....and the reduced valve train weight is also a big benefit.....

you put a big cam in a E head...and it wants to pull till it blows

see the very nice smooth power curve of the E engine with race cam... (green line) look at that torque curve...(ok not alot but a nice curve)

[fogleroller]

My experience... I have a 12/88 production date '89. I rebuilt my motor w/ the 9.1:1 pistons and I noticed a decent gain. When I put my motor in I installed a N1 single. Even w/ the addition of the N1 I noticed more torque.

This is exactly what I have planned. I have been posting at the other boards and all I get is, get rid of the KA24E and get SR or KA24DE, the KA24E is garbage.

I have a question for ya. I have a 90 S13 with the "E" engine. I just picked up an 89 SOHC with the 9.1:1 compression.

Besides the pistions and ECU, what else mechanically is different from the early 89 and 90's engines?

I want to build the block/head from the 89 and do a swap later. (with a PDM street cam) Do I need to do anything else?

Thanks.

[Nismo1182]

This is exactly what I have planned. I have been posting at the other boards and all I get is, get rid of the KA24E and get SR or KA24DE, the KA24E is garbage.

I have a question for ya. I have a 90 S13 with the "E" engine. I just picked up an 89 SOHC with the 9.1:1 compression.

Besides the pistions and ECU, what else mechanically is different from the early 89 and 90's engines?

I want to build the block/head from the 89 and do a swap later. (with a PDM street cam) Do I need to do anything else?

Thanks.

According to the FSM, thats the only diffrences. I plan to do the same except i pick up a later model 89 engine that will get rebuilt for turbo.

[C-Kwik]

the DE head is much heavier than the E, it is far more complex..and porting the E head is much easier than the DE, after porting both of them, the E head IMO is the better head ....and the reduced valve train weight is also a big benefit.....

you put a big cam in a E head...and it wants to pull till it blows

see the very nice smooth power curve of the E engine with race cam... (green line) look at that torque curve...(ok not alot but a nice curve)

DOHC's are more complicated than an SOHC head by design. And typically they are heavier. But just look at the differences between the use of the surface area available in the top of the combustion chamber. Unless you go to some type of an oval shaped valve, it would be difficult to get as much out flow through the SOHC exhaust port as two of the DOHC ports. Not to mention, the spark plug on a DOHC sits centered where the SOHC has it right about where the other exhaust port on the DOHC would be.

Put a nice big cam in a DOHC and you'll have a nice torque curve as well. Only, higher up.

As far as porting, I would suspect you can remove more material from the SOHC head. The DOHC needs much less though since it's got a bigger overall opening in the first place. And the valve is still going to be the bottleneck.

And this is not to say SOHC moors are bad. But I only posted to state a case against those that say the SOHC motor can make more power. But I would still argue that the DOHC probably has a higher power potential based on flow potential.

[Bboy]

I have a 1990 240sx, all stock except the intake & exhaust. I want more horsepower. I am planning on rebuilding the engine, but do not want to drop a fortune in it. I would like to get the car over 230hp though, without use noz or a turbo.Any thoughts or suggestions.

[robyc]

in my opinion, it would be cheapest to put a small turbo in to punch the car's hp up to 230, it would take a lot of engine work and creativity to bring a ka24e n/a engine to 230 hp, like creating higher compresion, and your only starting off at around 8.5 or so, you'd need to bring it up to at least around 10 or higher with use bigger injectors, considering porting/polishing/valve work and such so, again, turbo would be easier in general, and cheaper for the ka24e

[goshoryuken]

I have a KA24E in my 89 Fastback . . so I'll probably get it ported and polished and then add the basic bolt ons . . and perhaps go all out and get the best of everything for it. If I remain N/A . .I should make good power, but not as much as if I were to get a turbo, but the SOHC I have does better without turbo than with I hear ..

[S13DatsunRicer]

I belive the DE is better due to more power. But the DE has more timing chain parts to deal with and probally weights more then the E.

[kpark129]

I guess you never checked out

http://raceeng.com/showItems.a...=RACE

They sell 10.5:1 compression for $420 with either a 89mm or 89.5mm bore. They are forged too.

Sorry if this is a newb question but i am a newb.. If I were to buy the KA24E SOHC 10:5:1 forged pistions on this site will I be able to put it in my KA24DE DOHC?

[SHIEF]

I've been doin some # matching between the 2 motors, from this, site and what I've seen in person, and other peoples data too. On average, with similar, or exact mods done to each motor, the DE generally puts out about 15 more hp, but only 5-8lbs of torque over the E. Even with both heads having a good port job, etc. Granted no 2 motors are the same, but you get the idea here. But I haven't seen a E above 337hp to base anything else off of. If you have a DE in your car then do it up. If you have a E in you car then do it. While you do have a little extra tuning you can do with 2 cams, IMO your not going to make a bad decision either way, and you can just nod yes when they ask you "Is that a SR20!!!!?

[90lkn4swp]

SR20DET

[Altiman94]

Being that I've both a car with a ka24e and a ka24de powering them, I can make a fair comparison. Down low, the SOHC has alot more power availible. Once you get above 4k, the dohc takes over. The dohc feels like a much sportier motor with the pull being at the higher rpms. I do like my sohc however for the simplicity of it.