Swap options and MPG's.

[510tdi]

I've been digging around the Realm pretty extensively for a while now and haven't found much info on the mpgs folks are getting with their engine/tranny combos.
I've been planning a '69 wagon/vw tdi conversion for a couple of years. A tdi mechanic friend of mine helped swap a tdi into an old Mk 2 Golf and squeezed 72 mpg out of it. His own modded 2001 Golf tdi is only getting 40+mpg but it's doing 13 sec. !/4's with FWD. Are we gonna take that from those oil-soaked Krauts!
I've got a solid goon, tdi motor and Toyota trans. and I'm this close to pulling the trigger on the adaptor plate and an insanely expensive hybrid mechanical injector pump. But man, the $$ just keep climbing and I'm not that crazy about recreating the wheel.. Yeah I know, I could just go get a Jetta tdi but the VW electrical gremlins and FWD are downers plus I've been a 510 nut since I saw the BRE cars race at Watkins Glen as a kid.
As much as I crave the torquey pull of a turbo diesel I've started to reconsider gas engines. Is anybody out there getting great mileage out of their 510?
I'm not a power junky so something like 140-150 hp seems more than enough to have fun with 2100 lbs and rwd. With such a light car and a little modern tech it seems a person should be able to get 8-9 seconds 0-60 and 40+mpg...right? That's in line with some of the new compacts and they're luggin' around another 1000 lbs of fat.
Could you de-tune an sr20 or ka for torque, combine with a tall overdrive and rear end, and get those kind of results? How about some kind of EFI on the L20? De-tuned vg30?
Any personal experience or good ideas out there?
And yes I did get pretty excited by "Ted Nugent's" Nissan Turbo Diesel swap thread but he seems to have split the scene once he sold his car and those L20DTs and parts are apparently hard to find.
I'd appreciate any feed-back.

Thanks and Happy New Year

[McWicked]

The short answer is that aerodynamics plays a larger role in steady-state fuel economy than vehicle weight. Despite it's light weight, the Datsun 510 has the drag coefficient of a solid brick outhouse. So if you pull an engine out of a modern car, then cram it into a 510... whatever MPGs you save in weight, you'll most likely give back in drag. And of course...

...personal results may vary.

-McWicked

[510tdi]

Yeah< I guess aerodynamics is the elephant in the room but it's hard for me to imagine that a 510 wagon and a 2003 Jetta wagon would be all that different. Especially if the dime's lowered a little with a spook and the speed's kept below 65 or so.

Any MPG numbers out there? Keep it real though.

[Sleepys-14]

I have a ecotec swap (185tq) in my car, it will do about 35mpg on the highway. I think thats about the best your going to get out of a Kleenex box.

[datzenmike]

Agree on drag or wind resistance. To double your speed you need 4 times the energy. Roads are not level. A to B and back to A involves lifting the vehicle weight some amount. All things equal, light car will give better mileage than a heavy one.

YMMV

[okayfine]

I've been digging around the Realm pretty extensively for a while now and haven't found much info on the mpgs folks are getting with their engine/tranny combos.

There are some. But you'll have to consider whether the reporting parties have corrected their mileage readings for different tire sizes, rear gearing changes, etc. Speedos these days can be wildly off after 45 years of use and abuse.

it seems a person should be able to get 8-9 seconds 0-60 and 40+mpg...right? That's in line with some of the new compacts and they're luggin' around another 1000 lbs of fat.

You could easily get a 510 into the 6-second bracket 0-60. 40+mpg has not been achieved in a 510 AFAIK. New compacts do get that kind of mileage, however modern cars are much, much, much more efficient. Look at how much electronics are on a new car doing their magic, plus imagine all the efficiency gains automakers have put into play to meet tougher CAFE standards. Probably more loss through drag in the 510's half-shafts than in the entire drivetrain of a new Honda Civic.

Could you de-tune an sr20 or ka for torque, combine with a tall overdrive and rear end, and get those kind of results? How about some kind of EFI on the L20? De-tuned vg30?

You can make changes, but very few 510 owners have directly sought mileage gains over everything else, so you're still going to have to reinvent the wheel to a large extent. As mentioned, drivetrain efficiency is going to be a huge deal for you, and in that realm the newer the components the better. But if you're stuck using stock 510 pieces (diff, say, or halfshafts), that tech is 50 years old. You can certainly swap from halfshafts to CV joints for a small decrease in drag...but how much gas will you be able to buy for the $900 that the CV setup will cost you? Following along that route, how much mileage gain might you expect for $ spent trying to detune an SR or KA? Gas is still relatively cheap and the financial payback for a project like this seems far in the future (if at all).

As mentioned above, aero drag is going to be your enemy on the highway. A Jetta wagon has a Cd of .30. A 510 has a Cd in excess of .48 (.475 being a commonly cited Cd of the 240Z, and how does a 510 look compared to a Z?). Huge difference. There are some changes you can make to help, but it is a pig and huge gains are not possible. And a 510 is lighter, which makes an efficiency difference while accelerating, but not at constant speed on the highway as at that point you're not fighting the weight but the air.

For all that, my KA510 (electric speedo set up with GPS) would get 31mpg on the highway at 75mph with a 3.7 rear gear, spook, slightly lowered, 195/60/14 tires. Recalculated EPA rating for a '95 240SX is 26 highway.

[510tdi]

Thanks for the replies.

Sleepys-14 - Do you have any posts on your ecotec build? I looked, couldn't find. I'd really like to know more. Performance, cost, trans options,etc.

Okay-
As far as mileage accuracy and old speedos, one could get some help from Google Maps and be in the ball park right?

Sounds like the IRS rear end might be the source of considerable losses. Do you think a newer ford 8" solid axle in my wagon would be a little easier rolling?

So if you're getting 31mpg at 75mph with 3.7 diff. that sounds kind of promising to me. What are your revs at 60 mph?I'm assuming your car is pretty quick, like you mentioned, maybe 6sec. 0-60? What if one were to gear it up to a 3.0-3.5 rear end (depending on where the efficiency sweet spot of the KA is) to cruise at 65 as efficiently as possible but lose a little acceleration. Is the KA a torquey engine?

How plausible does this sound? Wagon with KA, overdrive, 3.2 diff, 0-60/8 sec., 35 mpg@65 mph.

My tdi plan uses a Toyota 5-sp with a .85 overdrive and a ford 2.73 rear end that would theoretically (according to the wallaceracing.com calculator) have me cruising the same as the Jetta tdi (2400rpm at about 67-69 mph) taking advantage of the diesel torque curve.

Any more MPG numbers folks?

[James]

If the wagon of which you speak is a 510 - its already solid axle. In stock form the 510 gets pretty decent gas mileage. Interesting project though.

[McWicked]

My completely stock L16 4-speed 510 averages about 21-23 MPG in mixed 60/40 city/highway mileage. Which is about the same mileage my 5-speed, dual SU equipped L20B, got. As a frame of reference, my lightly-modified 350Z sees about 24-25 MPG in the same environment. Despite weighing over 1,400 lbs more and making more horsepower than both 510s combined.

If you're looking to build some sort of Mileage King, there are definitely better base vehicles to start with than a 510 wagon.

McWicked

[510tdi]

Many reasons for focusing on the 510 wagon.

1) History-I had 3 510s back in the early '80's up in Alaska WAY before Craigslist and Ebay. They were SO hard to find back then! Still in H.S I'd stop by a parts store that actually had the 'How To Modify..." book on their rack of manuals and dream of installing BRE flairs on my future dime like Trevor Harris.. I think I read it cover to cover before my folks gave it to me for Christmas one year. Once a nut always a nut.

2) Light, responsive & fun to drive.

3) A classic still attainable by the unwashed masses.

4) Utility- We run a farm. Might as well have fun & save gas while running for parts or making small deliveries. I never have time for purely "fun" driving.

5) Simplicity-I'm really put off by all the complexities of modern cars.

6) I began by looking for a car that I could make into a turbo-diesel, high mileage car that fulfilled all the above AND

7) Importantly- pre-1975 (NO EMISSIONS HASSLE in Portland) AND

has a broad support network of enthusiasts like the Realm and Ratsun.

9) Preferably rear wheel drive. Or 4wd. I would have gotten into Subarus if their gas mileage didn't suck.

10) If I was gonna' mess with an old car it needed to be one that was built in fairly high numbers.

11) I want all this AND great mpg's. Hence the turbo diesel or something else quick and efficient.

CAN ANYONE THINK OF A BETTER CANDIDATE? Seriously, I'm open to suggestions.

I thought of a lot of possibilities. How cool would it be to drop a tuned up tdi into an old Citroen. Great aerodynamics but what a nightmare! Is there a DS Realm out there?

I gotta say I kept my idea fairly close for quite awhile not wanting too much negative feed-back. Finally decided to put it out here. You never know, someone may provide the missing piece of the puzzle or I may get saved from my own folly.

Thanks for your great input.

[James]

When my 510 was stock I was able to get 300 miles out of 10 gallons on the highway. Granted it was tuned well. My modified (cam, closed head, su's) L-18 with 5 speed will get 23-25 depending on how I drive it.

[510-Trevor]

I think your biggest MPG gains can be had at "city" driving where the diesel torque and low effects of poor aerodynamics will rule. After seeing a project on Spike TV's Extreme 4x4 called "green samurai" a long time ago I too have thoughts of this type of swap into a goon. http://www.powerblocktv.com/episodes/XT ... iii-finale Although mine have been more towards an "outback" 510 using the tdi-samurai drive train (just a pipe dream).
Be careful with your interpretation of the emissions laws, in Cali there is a common misconception that pre '75 are smog exempt where in reality they are just smog test exempt and you can still be on the hook if you modify your car. Oregon might be different.

[okayfine]

Sounds like the IRS rear end might be the source of considerable losses. Do you think a newer ford 8" solid axle in my wagon would be a little easier rolling?

How plausible does this sound? Wagon with KA, overdrive, 3.2 diff, 0-60/8 sec., 35 mpg@65 mph.

I'd honestly want a bigger return than an additional four MPG highway over a "normal" KA510. You'd also want to look at the KA itself. Engines typically are most efficient at their torque peak. But that's efficiency per gas unit, not the same thing as lowest mpg use. Automakers today are switching to small-displacement turbo engines. CA18DET retuned for torque?

Wagon will be slightly better on gas on the highway just due to the longer tail. But, then, what sort of driving do you do an on annual basis? On the farm if you're running parts and small deliveries, should you really be focusing more on city mileage, as mentioned by Trevor?

If you're not looking at the total financial picture you need to let us know this is purely a high-mpg hobby project. That'll change things. A Ford 8" fitted to a WPL will cost some monies. Like before, how much gas will that buy before you break even? Also, you're only really gaining access to choice of gearing by switching to the Ford axle. I doubt there's a marked difference in loss due to drag.

Is this a high-mpg hobby project, or are you trying to build an alternative to a Prius (which, honestly, probably has far more useable room inside, as would even a VW Golf)? As many of your improvements will come in drag reduction (mechanical and aero), and as most 510ers haven't paid much attention to drag reduction, you're going to be on the leading edge of much of this effort.

[Uber Deaf One]

My KA 510 with a 3.70 rear diff and 15" wheels can get ~35 mpg on the freeway at 65-70, if I baby it. That's about 2800 rpm.

I romp on this thing everywhere and get about 30 mpg. If I skip gears and shortshift at 1500 rpm I could probably push that a little bit.

[dislexicdime]

my tan sr20det 510 with a r180 with 336 gears got 30 mpg on the high way and that was with me getting on it and screwing around . philcas1987 also got 30mpg on the same trip with his single cam ka with a r160 rear end with 411 gears