I've noticed recently theres a bit of a trend of "CA is best" on social media and from my experience of driving both I don't really understand it so I thought I'd share my experience/thoughts having driven both.
When I bought the S13 it had a recently rebuilt CA in it so I had absolutely no intentions of swapping engines. In fact I wanted to keep that CA in the car for as long as possible. When the bottom end went on it I had a couple of options. Rebuild the CA, but since I didn't know any reliable engine builders with time to do it in the Highlands I wrote off that idea. Buy a replacement CA, which could very well have bottom end issues as well. Or go for a SR20, which is a more modern engine, used in almost all 180's and S13's (CA's were only in 180's for 2 years) and less prone to bottom end failure ...and the sumps are much easier to swap.
So I went with a straightcam SR. There were two reasons for going for the 180 version. One was the ease of the swap, I'd never done an engine swap previously so keeping things simple appealed to me. The other reason I went for a straightcam was the noise, all of the S bodies I loved the sound of had straightcam SR swaps.
The swap from CA to SR was ridiculously easy. I needed to repin one wire in the NSF wing, a couple at the ECU to clocks connector and put a resistor into my actual clocks for the tachometer.
Although the first start was not so easy. The car fired but ran like absolute hell. Speaking to resident UK Nissan wiring master Norfy we ran through loads to pinpoint the issue.
Which included stripping back the whole Engine loom looking for shorts as the coilpacks were only getting 8v.
It turns out when I picked up the SR the lad somehow had an S14 AFM instead of S13. So all this stress was all due to me not realising I'd been given the wrong AFM. This cemented my position of, the ECU does some weird shit when its got the wrong AFM.
So my CA18det setup had a Garrett T28r, Stage 2 Horsham chip, CA16 exhaust cam and running at 15psi. The SR20det had a Garrett T25g, Stock ECU and 14psi. The first drive with the SR I was blown away by the usability of the SR. The power was consistent all the way through and it kicked in earlier which was obviously due to the smaller turbo. The CA in comparison had all of its oomph further up in the range and its very noticeable.
I'm not sure if it is from the fact the SR is smoother through the revs but it definitely feels quicker. That is with less PSI, smaller turbo and without a "tuned" ECU for it.
So taking this into drifting, the CA always seemed to feel in between gears and when I watch back footage of myself any time I drop into second it pretty much would be hitting the limiter but 3rd would be too long. In comparison to the SR where I don't hit the limiter anywhere near as much.
Then there was also the time that I drove full outer at Driftland in reverse and the CA just wouldn't take 3rd gear no matter how hard I tried. I ended up having to use 2nd gear just to make it.
Here is the footage... As a caveat: this is my most embarrassing drift day. CA's on limiter are absolutely disgusting and I got got a warning from track staff. I spoke to Amjed with the CA R32 at this day to see how he did this layout and if I remember correctly he said he hated it for the same reasons I was struggling with.
To be honest my driving here really isn't great but I feel like if at that point in time I had the SR I would have had no issues with the layout.
So overall the SR is a bit more expensive but if you can afford it I would definitely suggest going SR over a CA as it is a much nicer power delivery. However CA's are ridiculously cheap, but this is due to them being plagued with bottom end issues and constantly being pulled for "better" engines. It's a lot cheaper to find spares for and as long as you steer clear of the chiptunes they can make good power, not have a hellish limiter and sound good. Look up Kane Launder's S13 running TD05 for a good example of this. But in my opinion, I'd rather have an SR.
Cheers