Let's start with my experience, keeping to the FAQ-style format as much as possible but the goal is to have others share their before/after experiences. Here are some questions that I have been asked over the years:
What model roadster do you have?
I have a black '67.5 SPL, or "low-windshield" 1600.
Although it is a 1600, the roadster initially had a complete drivetrain from a 2000, ie U20 and 5-speed:
Why did you do an engine swap on you roadster?
Several experiences led me to my decision to do an engine swap. I think its best explained in chronological order. I came from the world of Hondas and I had always fantasized about turning my daily driver EF-chassis Civic into a engine swapped sleeper. We called them "hybrids" back then. My first roadster was a '68 1600 with the stock R16 drivetrain. Although I had fun with it it was about as powerful as my Civic and in need of full chassis/body work.
I was at a point in my life where I did not have the time to do a full restoration, so having a dependable setup that didn't require constant attention was very alluring. My roadster ran like crap at higher altitudes, ie Mt. Shasta and during really hot or cold weather. Constant carb adjustments, spark plug replacements, starter and alternator failures, etc. didn't appeal to me. I did not want to "tinker", at least for now.
I met another roadster owner with a KA24DE drivetrain in his '66 SPL(Herb Petty) and it blew my mind. The thought of significant power gains, modern reliability, easy maintenance all wrapped up in a vintage roadster became my ultimate sleeper. I wanted one.
The seed was planted. I sold that '68 to get the current 67.5 SPL. It already had a hot-rodded U20/5-speed. I enjoyed it immensely for a few years, though still had the swap bug on my mind. Michael Spreadbury (spriso) had been building SR20-powered roadsters so he also inspired me. While on a backroads fun run with other roadster friends I hit a rock and my competition aluminum pan cracked a hole. With the car down I decided to start the engine swap process!
Why did you choose the SR20 over other powerplants?
I think this is one of the more "sentimental" decisions I made because there are many powerplants to choose from both Nissan, Domestic or period-specific. I wanted Nissan power to remain under the hood, again this has no bearing on functionality, it's just for fun. The SR is all-aluminum and relatively light compared to others, and fits well without compromising weight f/r. The 5-speed transmission shifter comes through the factory tranny tunnel hole with no modifications. Displacement is still 2.0L, so my "2000" badging remaine "true" and added to the sleeper effect
The SR is buttery smooth and high-revving in nature. A 7500rpm redline stock just seemed to feel "right" for the roadster to me.
Why not just build a U20/H20/stroker?
Goals for engine builds differ from person to person. My goal was not outright hp. I would have chosen a turbocharged variant for power goals. Instead, I chose a modern powerplant for overall driveability and reliability in addition to the modest power gains. Building a high horsepower engine can be fun. Learning about the parts and recipes, taking metal to the machinist to see how they work their magic etc., this can all be fun, gratifying and a great learning experience. It's just not for me at this time.
In terms of building a U20 to stock SR or KA power levels I had been quoted $5k from rebello to make my U20 a 200hp(crank) monster. I had to supply them with the carbs, which I did not have and are an easy $1k alone. Although it sounded enticing, it was still carbed and required summer/winter jetting and had the peculiarities commonly associated with that setup. Cool for most folks, but I couldn't live with it.
How much work is involved with the SR swap?
This is a tough question to answer because it comes down who does the work. You or a fabricator?
The basics for most late model drivetrain swaps into our cars involve sourcing the new drivetrain, framework modifications(motor and transmission mounts), and adapting/changing the existing wiring to support the factory-supplied EFI. I have many friends that have performed their own SR/KA engine swaps, but they have welding skills and access to tools. For my swap, I sourced the drivetrain and all parts needed and had a local shop perform the fabrication/installation. I paid an expert $200 to wire the car. Spriso Motorsports was a huge help back when I was doing my swap and they currently sell critical parts for SR installations. Remember though, the drivetrain may be modern, but everything else must be up to snuff around it...it's still a 40yr old car! Gauges and ancillaries need to be sorted. Brakes and suspension need to be freshened.
What is the cost of the engine swap?
This also depends on who is doing the work. You or a shop?
In late 2002, I paid $1,159.38 for my S14 SR20DE engine+transmission from Marco at SR20store.com. I highly recommend him, 10 years later!
At the time of this posting, SR20DE(T) prices range from $900 to $2500 depending on variant.
KA24 prices range from $300 to $800
GM Ecotec(NA) drivetrains are about $800
Miata drivetrains are $300 to $800
9 years ago I paid a shop 9k for a turnkey installation for an S14 SR20DE into my roadster. Dropped it off without an engine. Picked it up ready to drive.
I have about a dozen friends that have done their own engine swaps for $5k or less. They are talented, patient folks who got their cars up and running, then worried about beautifying them later. The SR swap is well documented thanks to Spriso and others that have shared their builds, so alotof the guesswork and expensive stuff is worked out!
It also depends on what level of detail you want in your swap in terms of cleaning up wiring harnesses, intake plumbing, powdercoating, etc. These things add up!
How much power does your engine make?
Currently it dynos at 156/136hp at the wheels on a dynojet
Bone stock it made 134hp/127tq at the wheels on a mustang dyno. For comparison, a stock KA24DE in a 510 makes 145hp/140tq at the wheels. Clearly these are not mega hp numbers. If you look at it from a tuning perspective, getting a U20/R16 to make this kind of power takes significant work, so in a way you have a head start in the hp game with the modern drivetrains. Whether this is significant or not is up to you. It never mattered to me, and serious hp junkies only need to grab a turbocharged variant and sky is the limit. Stock SR20DET motors start at 205hp and go all the way to 250hp from the factory.
What can I beat?
The stock r16/U20 roadsters have alway been quick little cars since inception. They can keep up with today's traffic just fine, imho. In a straight line I can't "beat" most cars these days with my NA SR-powered roadster. We can use our favorite Honda as a benchmark, the Integra GS-R which has 170hp or ~144rwhp equating to 17lb/hp weight-to-power ratio. I have an approximately 13 lb/hp weight-to-power ratio. I have run a mid 14s 1/4 mile at ~97mph. A Camry runs low 14s at 100mph! The SR20DET roadsters can hold their own with many supercars. for example 300rwhp in a 2000lb chassis gives you a 6.7 lb/hp weight-to-power. A C6 Corvette has a 7.4 lb/hp weight-to-power ratio! Of course, traction is the limiting factor for drag-strip launches, but boy is it fun!
What is it like to drive?
When I first drove my SR20-powered roadster it was an amazing experience. The drivetrain totally transformed the car. There were no burps, hiccups or backfires. No hot/cold starting issues. To this day, I still giggle when I stand next to the drivers door, reach in with one hand and turn the key to fire it up. No choke cable to pull in the morning. No gas pedal to pump before cranking over. To me, it was exactly what I imagined and wanted.
Performance:
Immediately the weight loss from the SR20 drivetrain is noticeable in such a light car. Before with the U20 the roadster weighed 2120lbs, after it is 2040lbs. 80lb instant diet! Throttle response and revving is just sooo smooth. The car has a much more useable powerband. I can short shift at 2500rpm most of the time and still keep up with the traffic. And that sound! NA SR20s sound glorious screaming to 7500rpm...
Daily driving: To sum it up: Get-in-and-go. The roadster became a car that I never worried about with respect to the drivetrain. There is no start-up protocol you need to inform your friend of before handing the keys to him:)
Long roadtrips: Do you carry spare throttle springs and points in your roadster on long trips? I do too, but only as backup for my buddie's stock engined roadsters. Fuel economy is amazing. It is hard to get under 30mpg on long trips and around town.
Track/Thrashing: All I wanted to do was drive this thing and that is what I did hardcore for the first 2 years since the engine swap. I put close to 25k miles in that time doing long roadtrips to shows from Norcal to Socal, track days at almost every track in CA, and a 400-mile/week work commute. No fiddling with carbs or ignition before/after track days or high elevation!
How is maintenance?
Service schedules for an SR20DE engine are at 30,000-mile intervals, a major tune takes place at 60,000 miles (when you replace the spark plugs). Typical maintenance items for this engine are the distributor cap, rotor, plugs, air cleaner and PCV valve. You can get all of the service parts for a RWD SR20DE at your local Nissan dealer except for the distributor cap, and that can be found through independent vendors like Spriso Motosports.
Gone are the things normally associated with maintaining a 40yr old vintage drivetrain!
Have you had any problems since the swap?
I have been driving the car with the engine swap since May 2004. That's about 8 years and of course there were some teething problems initially. I didn't have a working speedometer for about 6k miles because we had to figure out how to run the VSS with a new speedo. The SR's tend to move alot at high rpm and the initial clearancing of the crossmember had to be opened just a bit more for safety. A problem we sorted out on the racetrack was on the front straight at Laguna Seca: turbulent air from the cold air intake cause aberrant MAF readings above 105mph. We redesigned the intake tubing/MAF location, in summer of 2004. Since 2004 I have not had a single engine-related problem. I have changed the oil and flushed the coolant. I am probably due for a tuneup, but I have been so lazy with maintenance I wil get to it eventually. The rest of the car though has had minor issues and I expected that. The rear axle started to leak/whine most likely to repeated drag launches and track days. I had to upgrade the brakes. I had to have a new flex-pipe and exhaust hangers made. That's about it.
Why didn't you go turbo?
Ahh...the eternal question. I go back and forth on this. I used to be concerned with the turbo plumbing and packaging but it's all been sorted and proven with recent builds. I tell folks interested in the SR swap to go turbo if you want real power. Personally I regret not doing the turbo swap. Friends that tell me it is just awesome the way it is NA and I will ruin the "feel" by adding a turbo. Initially I was not interested in being stupid fast but hangin out with all of these folks with boosted cars becomes addictive. I want to be able to light the tires up in any gear. I can always turbo my DE motor, or just buy a DET and drop it in.
What cams are you using?
-from a fellow owner:
"I looked at your two you tube videos included re. the cam install and acceleration appears more aggressive. Actually based on your rwhp numbers of 159 you are right in the neighborhood of a stock S13 DET of 200 at the crank. The S6 JWT cam appears to have a bit more radical profile than C1, so I am wondering if that combination and a 4.11 LSD swap (which was one of my planned upgrades) would make for a quick light-to-light package."
I am using JWT C1 cams. Stock S13DET motors I'm sure will dyno's much higher than me especially in tq. But yeah only boost controller away from 250whp is simple...and tempting! I have 4.08 gears now...4:11s would be killer for sure. The C1s and S4s are nice because they are still streetable. I got a bit more lopey idle but it is still silky smooth, and fwiw we never got a chance to fully "tune" C1 cams with an safc or wideband...
I am really interested in tuning/aftermarket parts for the SR, any tips?
The SR20 is and has been the Chevy LSx of the import world. DE or DET there are tons of aftermarket parts available.
Simple mods like cams, exhaust, intake etc are all applicable to both motors. Turn up the boost on the DET and you can have endless hp at the your desire!
Ok so let's hear from all of you other late model owners, KA/SR, domestic, etc!
