Diesel in a white suit
 

I'm working on the details before I start but I'm planning an engine swap in an older Datsun.

Goal: 40+mpg and good performance

Planned engine: Nissan SD22 with a turbo added

Planned transmission: SD22 5-speed

Differential ratio: 3.36:1

Project chassis: 1981 Datsun 510 2 door sedan

Photos below:


https://www.fuelly.com/attachments/fo...a139e19457.jpg

https://www.fuelly.com/attachments/fo...e6487f296c.jpg


https://www.fuelly.com/attachments/fo...1ea7d683b6.jpg

I like those wheels.

The car's pretty clean, do you have interior photos?

Do you have specifications on any of this stuff? Curb weight, power from that engine (NA and/or guessed with the turbo), gear ratios?

the SD22 in N/A form is a bit weak
61hp @4000rpm 104 lb/ft torque @1800 rpm

turbo charged with intercooler Dyno tests show

109hp @4000 rpm and 133 LB/FT torque @1800 rpm

the transmission internally is the same ratios as all nissan 5-speeds except for 5th that is a taller .8125:1 overdrive

the car already has 3.36:1 gears in it so this is looking like a marriage made in Japan.

curb weight for this car is about 2200 Lbs the diesel will probably add 1-200 lbs to that with trans and all

the interior is as clean as the exterior but I don't have any photos :(

I want this car to be a statement that fun doesn't have to be inefficient

That torque sounds great. I bet you could enjoy a singificantly taller gear. If the tires are the same outside diameter as stock, you're looking at 2750RPM at 70mph...that's above your peak torque and that diesel should probably be running far lower RPM.

Calculations by https://f-body.org/gears

good thing I drive 60-65 everywhere I could swap the guts from a 280zx 5-speed they have a .73 5th. That would give a nice 2200 RPM 60 mph. The 3.36 gears are the tallest Nissan offered for this housing. Economically that's as good as I can get. I could swap the H190 out of the truck the SD22 comes in for a 3.16:1 ratio but that involves brackets and cutting tubes and all that fun. I am by nature a bit lazy and I think the 3.36 will do. I should also change up to the 205/50/15 tires to have the correct diameter that would bump my cruise at 2200rpm to 62 mph

I don't know much about diesel FE, but I'd guess that you want to be much further from your peak torque for cruising.

just found out the SD22 Transmission has the .73 5th gear so that's good news.
2200rpm 5th gear equals 60 mph with 195/50/15 or 62 mph with 205/50/15 with this overdrive.

you know more than me but what I've seen these Nissan diesels like to cruise at peak torque. interesting side note is if the engine could pull to the governed 4400 rpm it would go 121 mph... Thats better than the stock engine could ever do.

I double I know more about diesels than you do.

Remember that peak torque RPM is only producing peak torque with the go-pedal on the floor, so we're talking RPM but not power production. If you're producing 193 lb-ft while cruising, you're probably cruising at 160mph.

Anyway, you may be right, diesels might be most efficient at/near the same RPM as they produce peak torque.

ah yes but peak torque is also peak efficiency or I think it is.... I guess I'll find out.

Peak torque may or may not be peak efficiency (I don't think it correlates normally), but only if you have some use for all that torque. You may produce 193 lb-ft of torque very efficiently, but if you only need 40, you're wasting a huge amount.

But, as I said, without the go-pedal floored you're not getting 193 lb-ft at that RPM anyway.

I think it's just running at that RPM not running at WOT at that RPM.

Looks like the SD is not going to work so well however I have an option.
Nissan also makes an L-series diesel that produces more power and has a higher torque peak. 124 lb/ft @ 2400 RPM compared to the SD's 104 @ 1800 RPM.

I think the section I underlined in the second excerpt I quoted is the most telling. This would be a huge undertaking, except in the "if my aunt had a beard, she's be my uncle" sort of way. Amusing to think about but inevitably unrealistic.

Stock A4 chassis VW TDI (New Beetle from 98, Jetta from '99, Golf from '00) do better than that 40+ mpg AND will handle far better. Side air bags, ABS, traction control, A/C.... It's amazing how much technology has moved on since the early 80's.

The hoped for 2200 rpm at 60 is 27.3 mph per 1k rpm. Those generation VW diesels have 28.9 mph / 1k rpm. Is 2100 rpm at 60 mph close enough to your desired 2200?

The 4th gen VW Golf (Jetta, New Beetle) is stock chip limited to 4500 rpm, and with the exception of the N-B aerodynamics, has enough software limited power to pull to darned close to 4k in top gear. That's 116 mph with stock tune.
Chip tunes? What level do you want? I know of several daily street driven 200+ hp, 300+ lb*ft, A4 TDI.
You want rpm? Stage 6 (appropriate injectors, exhaust, turbo, and that level of chip) allow 6k+ rpm. The owner gives these instructions: "Floor it, hold it there until the tach pegs, then count to three, and THEN shift."
Gotta love keyboard tuning.

As a side note: My bigger, heavier, mid-90's Passats returned 50+ mpg over the 200+k miles I had them, ran 9.2 0-60, 18.2 1/4 mile, 125 mph sea level (and a disappointing 109 at Bonneville altitude), did track days at Mosport, autocrossed to the best of my ability and had 900+ mile range (1300+ in the wagons), with stock tune.


If the choice of the Datsun is for aesthetic reasons, well, there's no disputing tastes. If the goals are more quantifiable (40+ mpg, 2200 rpm, 120 mph) there are better ways to achieve them.

its mostly aesthetics I love the Datsun 510 shape and I know how to make them handle. As far as power is concerned I'm not really looking to set any records with this but 100 hp will beat the gas engine by 10. I just want to open a few eyes to the fact that a diesel can be fun and still be cool. I am well aware that VW makes a better car than this but they start life as much as 150X the cost of this car. I paid $150 for this I figure if I hit $5k building this I will have paid too much for something in the swap.

I will have help doing this... My Father is a retired Diesel mechanic so I won't be allowed to cut corners or make mistakes.

A little background on LD swaps. This swap is more common among the Z crowd and those guys have seen 56mpg as a best and 40 as worst. I figured my car will weigh less than a Z and has less U-joints so it's a touch more efficient in the drivetrain. I will have a little less ultimate power but oh well.

this should be fun.


BTW the lazy comment was to say I don't see any reason to swap differentials since the 3.36 will suit my needs perfectly.

here is a chart showing RPM and speed in 5th gear using the following parameters:

tire: 205/50/15

Differential ratio: 3.36:1

transmission 5th gear ratio: 0.73:1

engine HP peak rpm: 4400

RPM 5th Gear
500 14
600 17
700 20
800 22
900 25
1000 28
1100 31
1200 34
1300 36
1400 39
1500 42
1600 45
1700 48
1800 50
1900 53
2000 56
2100 59
2200 62
2300 64
2400 67
2500 70
2600 73
2700 76
2800 78
2900 81
3000 84
3100 87
3200 90
3300 92
3400 95
3500 98
3600 101
3700 104
3800 106
3900 109
4000 112
4100 115
4200 118
4300 120
4400 123

just to be clear the LD20T has a torque peak @ 2400 RPM

What about the REAL 510s, with IRS?

I would have used a pl510 if I had one. I have had a few of the 68-73 510s. Something in me likes the refinment that this one has over the better handling IRS cars. The price was right and it looks pretty good if you ask me.

If that $150 was the entry cost, and you've a self-imposed $5k limit, you'll be OK.
Me personally? For a "3 squares" design I'd have located a VW Fox, more than likely a wagon (ok, the wagon was "2 box") I could then use bolt-in, no modification, VW and Audi parts. Say what you will about the cars, but the "Mr. PotatoHead" parts interchangeability of VWAG cars is a blessing for those of us that refuse to leave well enough alone.

For fun that doesn't have to be inefficient, I have an oily rag.
Well, it's mine, but I can use it only when Mrs. doesn't want it that day....

nice cabby. The interchangeability is what I like about Datsuns too. The LD20 is the same as an L 20 or L28 so I can use a 280ZX transmission and get the OD I want.

just build it. we need pics (and videos would be nice too)

all kidding aside, a good project thread would be awesome with beginning pics and pics throughout. I assume at $150 that she wasn't running so you won't have before stats.

I have always thought that if you could find a good 40-50hp diesel that you could put in a geo metro, you could get stupendous mileage.

it will happen Hopefully I can start on it soon. I have to decide wether I want to bring it out here or move back to the west coast.

what's so special about cali?? (I assume there, maybe washington or oregon)

if you move, you can't race my buddy in the turbocharged mustang (if he ever finishes it)

turbo mustang VS a tdi Datsun you're kidding right?

it's a 4 cyl turbo. until he gets really crazy, you may have a chance.

it is the stock one out of a thunderbird (turbo coupe) it really isn't that strong (2.3liter I think)

plus, it would be fun just to see but the mustang is in pieces right now and it may be a while before he gets done.

who knows, it may end up behind his house as a planter.

a good friend of mine has a 2.3 turbo ford SVO making 375hp with few mods


My Datsun will have about 100hp a stock SVO is 155hp and if anything has been done 200 is easy.

I know he isn't making 375 but don't you have much more torque than he does. I think that the torque and hp are the same on that motor.

there again, his car doesn't even have a rear axle in it right now.

what was so great about california again??

there is nothing good I can think of about Kalifornia ..... Washington on the other hand. My whole family is there.

so it's washington, can't say anything negative about wanting to be close to family. they pull you out of the ditch when you get stuck (metaphoircally and sometimes literally)