Datsun Roadster Forum-311s.org

I have been inspired to create a FAQ and place to share your late-model engine swap experiences. I get e-mails frequently and I love to preach the engine swap gospel but the full inbox and one-sided nature of e-mails compelled me to get feedback from others. Perspectives from other owners may help those interested pursuing the swap.

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!

Wow, great overall Q and A primer - well done Alvin!

Nice write up. Where are the pictures? Sorry... Force of habit... Alvin, I'm used to 300 pics, ten words. Awesome to see the history behind it all, and $9k seems like a good deal. Given what you would pay for a Miata, you have 10x the groove...

Alvin, you keep raising the bar for 311s contributors!

WINNER WINNER WINNER of the 311s POST OF THE YEAR.

Alvin you answered just about every question, comment, and concern I had about a swap..

well done friend.

Alvin,
Start a new trend.
Be the first with a Rotrex supercharger!!

http://www.rotrex.com/Home.aspx

Have to admit, if mine was not a '67 2000 it would already have the swap. Hard to complete with the drivability, power and economy of a modern engine. Your car is absolutely beautiful and a great example of what can be done on a relatively doable budget. Nice write up.

That was a great read, thank you!

AWESOME write up!!! Thank you Alvin and I envy that vehicle. It is a work of art.

I also come from a Honda background and I can't believe I am so excited for a Nissan/Datsun.

Good to hear another GS-R driver's perspective. But I put a Jackson Racing Supercharger on my GS-R, so I think that's why I'm looking to the DET.

Thanks again. Great write up.

Alvin, thanks so much for this terrific post! It is a great review and I am going to continue to replay your video.... I love the sound and fury of the "black beast". Only one issue for me...

You're going to bring your car to the March 31 Mt. Diablo fun run, and after seeing and hearing it in person, I'll wake up the next day and turn to my wife and say: "I really need to start a Roadster project with an SR20DET engine swap". It being April 1st, she will laugh it off as an April Fool's gag. One problem: it won't be....then the trouble will start!

Great post for those who want a swap. Shhh...

No one tell Will.

First off, a FANTASTIC post Alvin, here is my contribution!

What model roadster do you have?

I own a 1966 Datsun 1600 Roadster



Why did you do an engine swap?

I came from the world of Datsun 510s—they were my high-school and college car, and back then, roadsters were “serious dollars”, and outside the scope of a broke student. Like a roadster, the 510’s stock 1600 engine left little to be desired, so engine swaps were accepted and expected if you were a die-hard 510 nut. I had done lots of swaps before I picked up my roadster, and after a year of limping along with the R16’s numerous issues (over heating, worn out SU carbs, lack of power), an engine swap was a logical progression.

In the late 90s, engine swapped roadsters were not the norm, and even though my lowly 1600 was going to live again with a new power plant, when I shared this opinion with my new-found roadster friends, I found quite a bit of push-back from the older roadster enthusiasts. They claimed I was completely ruining the car with this new-fangled engine—some in-fact being very vocal about their opinions.

I weighed these opinions carefully, but the car was slowly poising me with unburned hydrocarbons, and it was always a gamble on how long the cooling system would last before overheating. Soon, the decision was made for me when I stumbled on 3 RWD SR20DE engine/transmission combos for $400 each at a local engine importer… and the rest is history.

A lot has changed in the nearly 15 years since we started our first swap—the swap has been refined, and all the issues sorted out with well thought out, logical solutions. The Internet has made sharing these ideas much easier, especially with great resources like 311s.org. We have put a lot of cars back on the road with these swaps, and we find that owners with a swapped engine are far more likely to spend serious dollars to continue to improve their car, which in turn improves the breed. The critics have nearly been silenced, especially after a turn at the wheel of one of our converted cars.

I had so many people wanting to do their own swap that as our engine importing part of our business was winding down, I started to develop conversion parts and made them available on my website http://www.spriso.com.

A properly converted car gets better mileage, makes great power, has outstanding reliability, and when equipped with a catalytic converter (like many of our conversions) meets or exceeds emissions requirements, and that is awesome too.

Why did you choose the SR20 over other power plants?

At the time I was working for a Nissan dealer and my daily driver was a Sentra SE-R with a FWD SR20DE engine that I beat the living daylights out of for nearly 300,000 miles. The engine LOVES to rev, and makes great power in non-turbo form—add a turbo to the mix and the fun factor just doubles.

The SR is all aluminum construction, has twin cams, and is a compact package. Parts are plentiful, and you can buy turbo versions right out of the box.

Why not just build a U20/H20/Stroker?

Why mess around with another old engine, when you can buy a NA or turbo SR and make more power?

How much work is involved with the SR swap?



Lots. I like to tell customers that you are going to do LOTS of work up front, but when the car is done, all you need to do at that point is regular maintenance (like Alvin mentioned above).

If you are a first-time swapper, this project may seem overwhelming. We have heavily documented the conversion here and on my website, but there is no other way to put it that it is a tremendous amount of work. We figure about a year of weekends, though I have had customers that have done the conversion in about 4-months of weekends and evenings in the garage—it all depends on what life throws at you!

What is the cost of the engine swap?

How long is a piece of string? Ok, that is a smart-alecky reply to the question, but there are so many variables to consider. I have had customers do their swap for less than $3000, but I have had customers who have written a check to have us build a car that would buy you a small house—it all depends on what you are capable of, and what your resources are like.

How much power does your engine make?

My original swap was a 140hp, S13 SR20DE engine that did 130hp to the rear wheels. Here is a video of that run:

http://www.flickr.com/photos/15007794@N08/6852821098/

That engine was later upgraded to a S15 SR20DE that is rated at 165 hp (though that car has not been dynoed).



What can I beat?

Lots of stuff, especially if you have the turbo version!

What is it like to drive?



There are no bad days when driving a SR20 powered roadster. This engine will rev all day to it’s 7500rpm redline, and you drop 50 lbs off of the nose of the car, so turn in with the car is even better than the original. Handling is awesome with that extra weight off of the nose. We have built several cars in the 1950lbs range that have an amazing power to weight ratio.

These cars don’t beat you up, and I would not hesitate to get in my roadster today and drive it across the country. There is no question of reliability.

How is the maintenance?

Alvin covered this really well—people look at me funny when I tell them that I don’t like to work on cars—and it really is the truth. I like building cars, so things like oil changes, or other basic maintenance is not fun for me—thankfully, really other than oil changes, there is not much to do to a SR powered roadster.

Have you had any problems since the swap?

None that I can think of.

Why didn’t you go turbo?

Ahhh, the age old question. In my case, my parents, both in their mid 70s, regularly drive the car in the summer, so that would not make much sense for them. When they are done with their roadster days, I will upgrade to a turbo (because they are such silly fun!) but until then, the car still is plenty fast.

Other notes:

We have built just about every version of SR powered roadster, turbo and non-turbo, and they are all super-fun cars. Here are some notes:

Engine: Buy as new of an engine version as you can afford/find. I prefer the S14 and S15 versions in both turbo and non-turbo for packaging purposes (ie. intake manifolds, etc.) plus, you are buying a newer engine. There is nothing wrong with the S13 engines, though they are getting a bit old now.

Transmissions: We have done 5-speed, 6-speed and automatic SR powered engine conversions. The Auto was no fun (as you can expect) but suited the owner. The 5-speed is a standard box, the turbo has a .75 OD, and the non-turbo .85 (which works well with the 3.9:1 rear end). My favorite is the 6-speed as there is an extra gear between 1st and 5th gear so you are always in the right gear—TONS of fun!

Support systems: Remember, when considering a swap look at your chassis wiring (if it’s a pre-69 harness, I throw them away), and most of the time we just replace the entire chassis harness as the previous owners have usually got things so screwed up it is just easier to replace it all.

Brakes, more power, more brakes… fuel system, go with an in-tank fuel pump, external pumps are noisy, and have starvation issues with the stock roadster tank—you might think you are saving time, but really you are setting yourself up for more headaches.

Conclusion:

Swaps are not for everyone. I appreciate the patience and deep pockets some U20 owners have to keep their cars going—it is awesome, but not for me. I hear your arguments that someone needs to keep their cars original so people can remember what they were like originally—god speed brave soldier, I appreciate your efforts!

But for those who yearn for more, we have a well documented solution…. Come to the dark side… There are hundreds of threads here on 311s.org (in the engine swap section) and we have had some fantastic arguments over all sorts of swap related questions—read, read, read!

If you have a SR specific question that you can’t find an answer for, or want my opinion, feel free to drop me a PM here and I will answer it as quickly as possible—or head to my website for more inspiration…

Michael Spreadbury

Thanks Alvin and Michael! Inspiring read!

I was asked to chime in..... even though I don't have a SR. I did a complete rebuild on my U20 and enjoyed what it had to offer. I was difficult to balance/tune to Solex's and it would have unique issues at different speeds or throttle applications. After driving for a couple years I was getting bored with the power of the car and wanted to see what options I had for the U20 and nothing really got me interested.

I decided to look into doing a engine swap. I ultimately decided on the KADE because of how available this engine was especially because at the time these engines were a dime a dozen because of the 240 SR engine swaps. So I put my engine/trans up for sale, I was able to sell the entire set up for $3500.00. I bought 3 KA's, 2 transmissions, 2 wire harness and one control unit for a total of $800.00. When I was gathering these parts I couldn't pass up a good deal and since I didn't know what I had it was safer to have additional parts available.

I'm sorry I didn't take pictures or document my engine swap when I did it about 10 years ago. In fact I believe I was the last person to buy the KA engine mount kit that was available back then.

Back then there were no instructions on how to do this that I could find. I truly enjoyed trying to figure out how to make each obstacle I ran into work or how I thought I could improve how to install something.

To fast forward (back in time) once the KA was installed and running I couldn't be happier. My U20 ran very well so there wasn't a huge difference between the two engines but it was so SMOOTH and ran flawless. I did have to find a LSD because of how much torque the KA made I just kept spinning the R/R tire.

A few years ago I was bored again so I started looking into turbo's and then superchargers. I was concerned about how to plumb a turbo so I began leaning toward a supercharger and followed some of the 240 groups on their cars they've supercharged. Now I was hooked....

Luckily, about the same time Andy Cost was thinking about selling his supercharger set up he used for his roadster and I was able to buy it from him. Since his car was a SCCA racer his set up wasn't just a bolt in so I had to figure out how to make it fit in the engine bay.

Once I got the supercharger installed I loved the power and the OBNOXIOUS whine!!!! I had Z car garage tune the ECU to the new addition and I couldn't believe how much more power they were able to squeeze out of the engine.

Now I have to be careful how much throttle I give it in first and second gear because it can get away from you. I've never been stranded because of the swap I've done and I couldn't be happier with how my car runs.

Here are a few numbers that I do have.

U20 Max HP at the wheels 106.6 Max torque was 110.6

KA Max HP at the wheels with the super charger before it was properly tuned 159.05, torque 156.47

KA Max HP at the wheels after being properly tuned 180.72, torque 172.04

I only weighed my car once and it had the U20 and it weighed 2040. I know my car weighs less now because I had to lower my front end 1.5 inches after installing my KA.

I know this story isn't as well written or informative as Alvin's or Michael's but I hope it answers some questions and invokes others......

Ken, thanks for the write-up also. I currently drive a swapped GSR with supercharger car and I have never had a "turbo" car. I am hoping that the blowoff valve sound will be as satisfying as the "whine" that I have grown to love.

But in all reality, I just want a Roadster to drive right now. Maybe I can talk my wife into one more car...... There's always dreaming, right. lol