Datsun Roadster Forum-311s.org

A hot U20 is the easiest way to high performance. Everything is a bolt-up and only a +plus for the value of the car. KA might be the most bang for the buck because of the big increase in torque, but it still is far from a bolt-in.

As noted, an honest 150HP is a lot of fun. 175-200 is getting really entertaining. On past 200-235 is plenty. I've only driven cars up to about 225 or so. (U, KA and SR)

With a turbo and power above 250 or 300+, you'll certainly need a different rear end setup, rear suspension work and a lot of rubber to keep things semi-controlled -- and cost will get WAY up there with all the custom work.

To start with, I would think really hard about what you want to do with the car. I do laugh a lot though, that we all approach HP differently. I like to talk about wheel horse power..

Talking about 200whp U20 motors is fun, but I have driven one, and it was AWFUL of the street. It doesn't really even run below 3500 or so, felt like it was starving fuel or it had quit or.. Track motor? awesome.. The higher you rev it, the happier it was.. But you would not want to street drive it.

My 200whp SR20 is completely street drivable. It pulls fine from idle. But it will never be at home in a vintage race.

You want to cruise around and have fun on the backroads? Stock SR or U will both make you happy. I honestly don't think either will detract value.

You want to go abuse the motor and trans? Go with an SR.. They love it and if you do blow it up, a low mile JDM motor is 1000... Save the U parts for the people who need them.

I love my SR. I cannot wait to drive my new U powered car. They will be incredibly different. I think they will be pretty close on power, but very different..

I absolutely agree with JT, although I would drop his power cutoff, and say above 150hp, you will want a different rear end set-up, and the rear suspension work..

I have owned R engines, U engines (both SU and Solex), and 3 SR20DE engines (S13, S14 and S15 Autech).

My 1600 was fun but I sold it after I purchased a 2000 because I liked the power increase.
My stock SU 2000's were even more fun to drive but the two engines I had never seemed to run strong but got great gas mileage (on the highway about 30 mpg at about 65-70 mph). Stroker cars ran as well or better than my car.
My new B cammed U20 with Solex carbs is a completely different car to drive. Although I'm still working to get it dialed in, first impressions are that this engine is world's better than my SU engines. Since this engine was build by a pro, I can't really say that the difference is the carbs and cam or just in being a fresh, professionally built engine (or maybe all three). I have yet to dyno this engine but it's stock so 150hp at the crank. I've been told I'd be lucky to get 26 mpg on the highway now (running 3.90 gears).
My SR20de impressions are that the S13 (140hp rated) had similar power to my older SU engines but was smoother, the S14 (165hp to 169hp rated) felt quite a bit more powerful (128 whp), and the S15 Autech is just awesome with a factory 200 hp (currently 155whp but hoping for 170whp). The S15 also got over 26 mpg in around town traffic to and from work for two weeks (also running 3.90 gears).

I plan on building another engine for my 68 2000 and will install a B or C cam JT68 is building me two heads right now but will stick with SUs.

The car I drive is based on my mood. They are COMPLETELY different.

Shannon

I have broken the rear member twice with a hot U20 engine.

RCMike wrote:To start with, I would think really hard about what you want to do with the car. I do laugh a lot though, that we all approach HP differently. I like to talk about wheel horse power..

Talking about 200whp U20 motors is fun, but I have driven one, and it was AWFUL of the street. It doesn't really even run below 3500 or so, felt like it was starving fuel or it had quit or.. Track motor? awesome.. The higher you rev it, the happier it was.. But you would not want to street drive it.

My 200whp SR20 is completely street drivable. It pulls fine from idle. But it will never be at home in a vintage race.

You want to cruise around and have fun on the backroads? Stock SR or U will both make you happy. I honestly don't think either will detract value.

You want to go abuse the motor and trans? Go with an SR.. They love it and if you do blow it up, a low mile JDM motor is 1000... Save the U parts for the people who need them.

I love my SR. I cannot wait to drive my new U powered car. They will be incredibly different. I think they will be pretty close on power, but very different..

I absolutely agree with JT, although I would drop his power cutoff, and say above 150hp, you will want a different rear end set-up, and the rear suspension work..

Mike
JT most always refer to BHPs where I think you always talk WHP

Having discussed this with him many times I know he will be the first to tell you that after 185-190 BHP (~150whp) a U20 suitability for the street start to come into question

The real big driveability advantage in the SR option is the variable cam timing on some (all?) versions. The cam is the brain, and you can have dual personalities with variable cam timing. One of the best upgrades in engine technology in my opinion. Just listen to RCMike' s engine when it switches cams... wow. That's cool. To get a U20 to hit close to that you have to have a stupid cam for the street, making it no fun to drive.
My engine is fairly well built but is still very streetable. I will put it on the dyno next spring when I reinstall the Isky cam, and I expect it to do well. But it cannot compare to what RCMike's engine could do. 40 yrs of technology...

Greg:

The VCT (variable cam timing) that started with the S14 is a nice addition. Mike's engine is a VVL (variable valve lift) which was only available on the front-drive engines (unless Kevin D performs his magic and swaps the cylinder heads). The VVL is what enables Mike's car to turn radical at about 5000 rpms. It's like flipping a switch and changing the cam profiles.

Yep, I was definitely talking crank horsepower (engine dyno) and was not implying a 200 hp U20, rather 200 generic horsepower at the crank.

The only very high horsepower roadster I've ridden in was about 225, and it was fast. Similar to a small block V-8 Zcar.

Thanks for all the great information!

I'd like to use the car for spirited backroads driving and autocross. It doesn't need to be a 1/4 mile monster or anything.

U20,kA,SR,R20_stroker all good choices!

I may try a Vq or 2J for fun one day, but for now there are lots of U20s on my plate!

How about a QR adapted to a FS5W71C?

I think we can all agree that QRs are not Nissan's finest work....

fj20spl311 wrote:How about a QR adapted to a FS5W71C?

Why?

The 1st gear ratio on a Frontier 6-speed is too low at 4.638:1
Direct Inject means more HP/CC

So I've been down this road before so I'm going to add my hay penny.

Which engine? Why? What's the cost? Difficulty? so on

Its not easily figured, because, as has been said above, there are so many variables that are solely subjective base on your tastes, preferences, ability and funding. So this is what I did. At first I listed my desires and their feasibility verses ability and cost. What I decide was that I wanted no less than 200 at the wheel and that $15k to $20k was going to be a realistic range. I wanted drivability and reliability. Yes high hopes!! (or at least I was high and dreaming )

The list of engines I liked went in this order:
-Toyota Beams motor; 200hp N/A engine
-KA24DE turbo or blower torquey motor
-SR20det high rev

The Beams was what I really liked and wanted. I just think its cool to get 200 hp out of 2liters naturally aspirated. But going to be a hard fit and there is next to nothing about the engine technically in English for support, so no. It was between the KA and the SR. In my driving experience I found that I prefer lower reving torquey motors. So when I found a KA, what I thought was a good deal at the time (it wasn't, but what ever) I went for it.

That's my story hope it helps.

There's a ton of support for the KA and even more for the SR. I find that it is fairly easy given my skill set, it just requires time and money more than anything. But it all really comes down to you. Just do a ton of research and do what YOU want and what YOU are comfortable with.

Matthew