Datsun Roadster Forum-311s.org

Hello All,

Hope everyone is well. Havent been doing roadster stuff lately.
But I decided to come and visit the forum and see what everyone
is up to.
I have been reading some of the post about swapping motors.
Im have not completely decided yet , but would like to get some
feedback..
I have a couple of roadsters both with a U20, so I know how the
car feels with U20's in them.
Ive had a chance to drive Alvin's U20 Powered roadster once and
it does run really well.
Of course I didnt get a chance to really "drive it" .
I have read some threads comparing the 2 engines on a dyno but
its really hard to compare them that way.
I might have missed some threads , but thats as far as I got.

Thanks in Advance for your comments...and Advise.

You know, I have never been in a U20 equipped vehicle when driven hard. Just little trips around town. So, I cannot give you an idea of the differences. I can say that the SR has so much more power than an R16, or L16 (hell even an L20), though.

Alvin has first hand experience with his car.

Alexi and I drove side by side down to the San Carlos Breakfast Meet, we toyed with the throttles a bit...He might have some comments...

After the work to do the install, it is obvious that I spend more time driving the car than working on it, that is the clincher for me...TR

I've got a KA24DE in my roadster. It fits easier into the Roadster without needing to cut the frame. In stock or mildly hopped up form it is a better motor than the SR20. It has tons of torque which the U20 or SR20 don't have.

I've heard this comment a lot, but I think a bit differently...

How much torque do you need/want in a 2000 pound car? The SR20DET with a 3.7 rear end(!) does not get traction at any RPM in first gear at full throttle. In second the tires break free at the shift and again around 5000 RPM.

My thinking is, unless I can get that torque to stick to the road instead of roast tires, what good is it?

The lighter motor and higher revs are a lot of fun to drive.

Of course, improvements like an LSD will help a lot, but that is a big project in itself in addition to the motor swap...

Alexi should have good input as he prefers KA's, too. Maybe just for cost?

Cost is one of my main concerns. I purchased a KA24DE with the tranny, accessories, computer, harness, and everything else for $255. You can't even get an SR20DET shipped to you for $255.

The KA and tranny also weigh less than the U20 and 5speed (or 4 speed).

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I totally agree with all fronts, although the shipping for my front clip was $100, as I bought it from someone that had it local and the second I picked up (although the gas was about $100, also!)...

I agree that a SR swap is more expensive than a KA, but you get a lower mileage engine, also.

Nomad, you didn't mention anything about cost in your previous statement that a KA is better than an SR. Except for cost, I do not see any way that a KA is better than an SR, NA or Turbo. The lightweight SR and all around newer technology coupled with the fact that the KA was designed for truck use, unlike the SR which was designed for auto use all give the nod to the SR...TR

As a SR20-SET owner, I'd like to weigh in on the discussion, and not in the way you might think.

I've got one way the KA is better than the SR that hasn't been mentioned yet. Durability. Yes, I know the SR will make 500 Hp on a stock bottom end. The engine is amazing when absolutely everything is perfect. Deviate slightly from perfect and the SR is a very unforgiving engine. The SRs have a nasty little habit of spinning main bearings that the KAs don't seem to share. The KA seems to be pretty much bulletproof and if you do nuke it, the parts are available and cheap.

I've seen more "I have this strange ticking noise at X RPM" posts on Freshalloy.com and the SR20DE forum than I care to think about. The ticking noise my engine developed after I lost all my oil has me pretty freaked out! I'm not it the mood to swap main bearings...

I prefer the SR20 myself, free reving , light wiegh motor. How can you say a KA takes less fab to put in ?

Just my 2 cents.


Were is Will talking about his built U20.



Crazy Backyard Builder

Dave,

That is scary news indeed! I have not heard this before...

Isn't your stereo loud enough to mask the engine noise? TR

Ha! What stereo? That sounds like a fix my girlfriend would try. She drove her Subaru around for 80,000 miles with a sticker over the check engine light. The bulb finally burned out. Problem solved!

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I don't want to get into a flame war here or an SR vs KA battle. Both have been done in the past. I can tell you that there were several reasons I chose the KA over the SR20.

1. Cost

I admit that I got a good deal on my motor. You just have to keep your eyes open for the diamond in the rough. I recently purchased a spare KA24DE motor for a whopping $55. The spare motor is complete with all the fuel injection parts except the throttle body and MAF. It has a broken cam chain guide and may need some new parts associated with the guide falling into the oil pan. I don't think it will cost much to fix. Definately not $600.

2. Parts availablilty

The parts are pretty cheap and readily available for the KA. I don't think it is too much of a problem to get SR20 parts either. Both are much better than an R16 or U20.

3. Performance potential

The KA24DE has every bit of power potential as the SR20. If you visit Freshalloy much you will find that there are several 450 HP KA24DET's running around. The difference is that the KA24DET has a ton more torque than the SR20DET. True power can be measured by taking the area below the torque curve on any dyno chart. A motor that has more torque and similar horsepower will be the stronger motor. I guess what I'm saying is to compare apples to apples. In similar states of tune the KA beats the SR. True a KA24DE won't have the power of an SR20DET but a KA24DET will have the power of an SR20DET. It is correct that the KA bottom end is bullet proof. All you have to do is remove the oil pan and see the massive main cap cradle to realize the strength in this motor.

4. Ease of swap

I won't say that the swap is any less trouble with the KA than with the SR20. Both require a lot of time and effort. The thing about the KA is that you can do this swap without cutting the frame or cross members. The SR20 requires that you cut the front cross member. For me it didn't make much difference because my car will never go back stock or have any real value associated. For some people the idea of not premanently altering the car is important.

I have one reason that I may consider using an SR20 instead of a KA24DE. It is weight. If the car was a road going car I would not even consider the weight as an issue. The KA24DE and tranny are at least 25 pounds lighter than a U20 and probably more when using a tiny alternator and tube header.

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It is your car, swap in what you want. The debate of high rpms versus loads of torque versus lighter weight versus stronger designs can run ad nauseum. The guy to ask would be the guy that has done and driven both. If I recall, he posted and said that he prefers the KA. Torque is what puts you back in the seat. RPMs sound good, but they are not what makes the stop light drags fun.

Oh, and before the subject comes up, Mike did say that he is doing another SR20 swap - but it is for a customer.

Personally, I like stock. If you want blinding speed, don't limit yourself to a 4 cylinder. There are herds of options. A local guy has a MG Midget that has a bridge ported (or was it peripheral ported - not sure now) 13B Mazda motor. He is only making 350hp though. Not bad for a car that weighs less than 1200lbs. If I am going to swap, I want something that sings to ME - a small block Ford. I have a virgin 289 in the garage and some fun parts. I will likely put an RV cam in it when I build it for the same reason that I put one in my Mustang years ago. Torque is fun. Was the old Mustang fast? Well, it buried the 140mph speedo on a couple of occasions. Fast enough. No idea on power, but it had a nice thump to it.