the whole DE vs E debate was a good thread, but I was just wondering what makes the SOHC have more potential than the DOHC? I used to be under the assumption that more valves = more hp, but I know that is not true. and how much modding will you have to do to find the HP potential point where the E overtakes the DE? thanks in advance
McAdam
what makes the E a better motor than the DE?
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quiksilvia
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Actually, the E also has more torque than horsepower, just like the DE. 152 ft/lb of torque at 4,400 RPMs, and 140 horsepower at 5,600 RPMs, if I remember correctly. You have the 15 HP gain with the DE, but the gain in torque is only 8 ft/lbs. There are more after market parts avaiable for the DE, but overall, I'd say both engines have around the same potential. One thing to watch out for on the E is the timing chain tensioner/guides failing, along with the chain wearing a hole in the front cover due to the lack of the guides. Happened on my 1990, evidently long before I got it. Rebuilds aren't cheap, which is what you need to do when you have coolant sitting on your bearings after leaking into the block. :-)
elbles you are right it is 140hp @ 5600 and 152 ft/lbs @ 4400. As far as I can tell the E handles modification better than the DE for NA. IE if you put on I/H/E you will gain more torque on the E than DE (but you are still starting 8ft/lbs down). Also the E is mapped out by Nissan Motorsports. And the DE and E would have made about the same stock power if the compression ratio was the same. The DE is 9.5:1 and the E is 8.6:1. I also believe that the ECU on the DE makes another large difference in the ignition advance that gives the DE an advantage in stock form. Bottom line IMO both engines are good platforms and one of them doesn't have much an advantage over the other. I would personally use the E just because you only need to P&P 12 valves and buy 1 cam.
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Topless240
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- Joined: Tue Feb 11, 2003 3:33 pm
In general you would want a lower compression motor for boosting. In this case the E would be a better choice as it is a lower compression motor than the DE and therefore SHOULD be able to take more boost with less detonation. There are other variables involved in boosting motors but compression is one of the big ones. David
Correct. The 89 and 90 models both used the KA24E, with minor differences between the two years. One of the larger changes between the two years is the compression ratio; I know my 90 runs 9.1, not sure about the 89 though. (9.6 maybe?) Anyone know for sure?robyc wrote:the only reason why i ask is the difference in the number of valves? oh, and i'm new so was it in 1991 and on when they started making the DOHC 16valve engines, making all 89-90 sohc 12 valves, right?
Also, there are more differences between the KA24DE and the KA24E besides the number of valves. Entirely different head with different bolt pattern. I'm sure there's more differences too, but that's the one that stands out in my mind.
elbles wrote:According to the FSM for my 1990, it lists the CR as 9.1:1. I suppose it's possible the FSM is wrong, but I'm just going by what they said. :-)
Wow, i just opend up my 90 FSM and on page EM-46 is DOES say 9.1:1 CR. But this is wrong. My guess is they used the same chart from the 89 FSM. The 89's had the 9.1:1 CR and they lowered in for the 90 to improve driveability. Even if you go to the dealership and ask for the 89 9.1:1 CR pistons, you will get the 'updated' 8.6:1 90 model pistons by default. Unless, of course, you get them from NissanMotorsports. The piston dimensions are identical, except the 90 8.6:1 had a slight dish to them, while the 89 9.1:1 were flattop.
JNM240 wrote:Wow, i just opend up my 90 FSM and on page EM-46 is DOES say 9.1:1 CR. But this is wrong. My guess is they used the same chart from the 89 FSM. The 89's had the 9.1:1 CR and they lowered in for the 90 to improve driveability. Even if you go to the dealership and ask for the 89 9.1:1 CR pistons, you will get the 'updated' 8.6:1 90 model pistons by default. Unless, of course, you get them from NissanMotorsports. The piston dimensions are identical, except the 90 8.6:1 had a slight dish to them, while the 89 9.1:1 were flattop.
Heh, didn't know that. Thanks for the information. Both motors were rated for the same HP/torque, right? Do you think a 90 is better than a 89, or vice versa? I guess the 90 might be better for turbo with stock internals, but otherwise? Not that it matters a whole lot with my engine; a rebuilt KA24E, and I'm not sure if the rebuilder used the 8.6 or 9.1 pistons. :-(
JNM240 wrote:I second that!! hehe But the DE can use the (much) cheaper SOHC pistons to gain compression, while the E needs to get custom forged pistons made. Mine cost me $520.
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.
AAAAAHHHH WHERE WERE YOU 4 MONTHS AGO?!?!
hehehe
Thats ok, i lost, what? $100? And 2 months of waiting? Doesnt mean the end of the world. Really, tho, thats a great link
As far as turboing on stock internals, either motor would do the trick, but you would SERIOUSLY want either a REAL low mileage motor, or a complete rebuild. If you are doing the rebuild, get the forged pistons, and strengthen up the bottom end.
As far as all motor between the 89 and 90, you are right, they are identical. I guess the difference between the compression ratios of the 2 years had more to do with knocking and low quality gas. They were betting on the lowest common denominator putting the worst gas into their car and probably decided it best to lower the CR just a hair to be able to use the worst gas around and not knock. But this is speculation.
hehehe
Thats ok, i lost, what? $100? And 2 months of waiting? Doesnt mean the end of the world. Really, tho, thats a great link
As far as turboing on stock internals, either motor would do the trick, but you would SERIOUSLY want either a REAL low mileage motor, or a complete rebuild. If you are doing the rebuild, get the forged pistons, and strengthen up the bottom end.
As far as all motor between the 89 and 90, you are right, they are identical. I guess the difference between the compression ratios of the 2 years had more to do with knocking and low quality gas. They were betting on the lowest common denominator putting the worst gas into their car and probably decided it best to lower the CR just a hair to be able to use the worst gas around and not knock. But this is speculation.
Sorry, don't have answer to that, but I was reading HCI about a turbo in a Focus, and the author was saying a better built N/A motor is going to make adding a turbo a lot better overall. His point was saying that a motor built best for N/A conditions will need less boost from a turbo to perform the same as a motor being built for strength. (which kind of makes sense to me) Just to see what you have to think about this concept. This makes me think that the 1990 KA24e is better that the de engines for turbo applications.
special_K wrote:This is somewhat unrelated but... I always hear people say that nissan motorsports makes a lot of parts for the ka24e, but dont they make anything for the de? Is there like an online catalogue or something...?
Courtesy Nissan has an online catalog of sorts at http://courtesyparts.com/nismo/s13/. If you look at what they have, a lot of the engine internals are listed as SOHC only, so my guess would be Nismo's stuff tends to be biased towards the KA24E. Maybe they think it's the better engine to start with, maybe they think it's the one that needs the most help. Hard to tell. ;-)
Hey thanks for the link elbles, you were right they seem to have a bais towards the sohc. Anyways now im confused, I am in the process of looking for an s13 and now im not sure if i should go for sohc or dohc. I still think that in the end the ka24de wouldnt be that much different to modify than the e. Plus you start out with more hp and tq to begin with. My current car (stanza) has a ka24e thats in great condition and i raced my friends 93 240 once and he totally killed me, but then again my cars fwd...
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Nismo_Freak
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The DOHC will in the end make more power. The reason is because you can tune the two camshafts to make the most power. You can advance an intake gear and retard the exhaust gear. On a SOHC you cant do this. You can also properly change the duration and lift of the cams to make the most power. The head can be re-worked to flow the amount of air needed. The timing chain itself isnt an issue. The chain can hold more power than the motor would ever make n/a. Look at the n/a 4 cyl. motors making a ton of power in Japan, they are all 5 valve or 4 valve.
JNM240 wrote:Wow, i just opend up my 90 FSM and on page EM-46 is DOES say 9.1:1 CR. But this is wrong. My guess is they used the same chart from the 89 FSM. The 89's had the 9.1:1 CR and they lowered in for the 90 to improve driveability. Even if you go to the dealership and ask for the 89 9.1:1 CR pistons, you will get the 'updated' 8.6:1 90 model pistons by default. Unless, of course, you get them from NissanMotorsports. The piston dimensions are identical, except the 90 8.6:1 had a slight dish to them, while the 89 9.1:1 were flattop.
Someone had posted this a while back about the 89-90 engines:
http://wac.addr.com/auto/240sx/240sx.html
The early 89's had the 9.1:1 compression and no IAT (intake air temp) sensor. Late 89 and all 90 models were changed to 8.6:1 and the addition of the IAT. What would you think the gain, if any, would be if someone put a early 89 ecu into a late 89/90 car or vice versa?
Yes, the KA24DE starts out with more power, and will *probably* produce more power with a given set of modifications. But the two engines are fairly close from the factory in just about all respects, including reliability. If you're looking for a cheap fast machine that can get done fairly quickly, a 91 + with the SR is probably the way to go. No rerouting of the power steering lines required in the 91+ 240's, and a SR20 clip can be had fairly cheaply. If you're looking for a reliable motor that's competitive with what's out today, either of the KA's can be brought to that level, with less than $1500 in parts easy. And without VTEC too. :-)