Atilla the Fun

For the few of you who would consider a turbo-diesel third-gen, what would you require of it, in the war of MPG, and in the way of performance? And at what cost? Would this be a second car to your gasoline-fueled third-gen? Those who love Top Gear UK remember what Jezza did with that Jaguar, and how could you not be impressed with his 49.1 MPG at 77 MPH? This board has discussed the obvious choices, the Detroit 6.2 / 6.5, and the DuraMax. Have we considered the Cummins 4BT? I wouldn't. How about the VW Jetta TDi? Output like a stock LG4, but just as responsive to upgrades. I like speed, but I want a third-gen commuter. The LSx swap is a good compromise, but it won't do 49.1 MPG at 77 MPH. I have my eye on an '83 Berlinetta, with a failed 2.8 in it. I can get the Jetta engine for $2,000. Am I on to anything? Of interest?

Orr89RocZ

iTrader: (20)

I'm not a fan of diesels but the concept is interesting. You can make some good power, insane torque and get good mileage. BMW made a tri-turbo diesel for their M series performance cars. Its suppose to get combined 44 mpg and made 381hp 546lb ft of torque...something a TPI guy would love to drive!

I guess none of the truck diesels would fit?

Street Lethal

iTrader: (16)

In my opinion, so everyone please take it just as that, there really is no reason to go diesel for performance and miles per gallon. Awhile back, Car Craft w/their Real Street Eliminator match up wrote about a Grand National that ran twelve seconds in the quarter mile, while averaging 47-mpg during a 61 mile test journey. The car was equipped with 40-pound Lucas injectors, exhaust, chip and 3.73 gears out back. Tom Chou significantly leaned out the mixture in the chip during idle and cruise, but brought it back under boost of course. With the advent of so many affordable flash systems out there, there is no question he could have went so much faster in the 1/4, while getting the same, or very similar fuel mileage. I'd obviously fatten it up a lot more that Tom did though and would be happy with 35-40 mpg...

Orr89RocZ

iTrader: (20)

I plan to test my turbo 400 mpg with the big heads/cam and try leaning it out alot and also different timing.

40's mpg for a 12 second car is getting it done! I'm impressed. My LS1 is stuck in the 19mpg range at low 12 second passes, and its reading mid 14's air fuel so not sure how much there is left in it...thats with 3.73's. 2.73's it would get 24mpg on a decent drive. I miss my highway gears but now my driving is not as much highway as before, so the 3.73's may stay for now.

I just dont like how diesels sound...and most tunes tend to smoke alot. I know you can tune them to make power and not smoke as much but they all tend to have alittle bit of black soot from time to time.... Not a fan of that.

Fallen2603

Attila the Fun,

Two words: DO IT.

Atilla the Fun

The 6.2 requires oil pan sectioning and notching the crossmember. I know, I test fitted it. Bashed my a/c box, too, dangit. Otherwise, it bolts in like any SBC or BBC, weight and size are close to the BBC, and then it's just the fuel system and exhaust, and the maximum possible radiator, since IDI diesels shed so much heat into the coolant. I could re-visit this with my '84 T/A.

Atilla the Fun

I remember that issue of CC, and I remember reading that article. Even at 18:1 A:F, what he claims isn't reasoinable. A couple of years later, on another forum, someone exactly copied that guy's claims, and the only way to do it was shutting the engine off and coasting in neutral, a lot. Plus just buying all his same parts was big money.

Atilla the Fun

Something's wrong. I know for myself, for fact, that an LS1 4th gen, pure stock with LS1, T56, 3.42:1 and 235/55R16s can do 31.1 MPG at a steady 65 MPH. Your cruise RPM with the 2.73:1 axle should still have you near 30. Doing 27.8 MPG at 60 MPH has now been done, with a carbureted 350, 700R-4, 3.08:1 and 215/65R15s. Keep at it.

Brando5641

iTrader: (-1)

I got 30.2 going 70 with my lm7 auto 2.73's

Orr89RocZ

iTrader: (20)

Well i never in my life heard a LS1 fbody getting near that mileage, but the vettes I have heard get near 30mpg, even with mild cams. They are lighter, my hoss is 3686 lbs with me in it with almost no gas...its a big car. They My car aint 100% tuned for mileage, its just got some bolt ons. Most of my mileage went down due to the 3200 stall so my city mileage is hurting but the highway should still be much better. I have to get it retuned after I rebuild my exhaust...rich in some spots WOT but cruise rpms shows a nice steady mid 14's to 1 air fuel.

Mine is an auto so its mileage is always less than a T56. We'll keep playing with it but its soon to be retired from daily driver status

Atilla the Fun

I like that, thanks. Orr89, you're tuned fat. 14.7:1 is for emissions, not MPG. Best MPG is closer to 17:1, though 18:1 is possible if you keep perfecting it.

Jim85IROC

iTrader: (2)

My buddy claimed that he knocked down 28mpg in his 99 SS automatic on the highway. I tend to believe him, because my 91 Corvette could do 28mpg at 70-80mph on the highway, with a combined trip mileage of 25mpg, and that was with a modified TPI motor and 3.55 gears.

Brando5641

iTrader: (-1)

i also got 30mpg with a 6 speed 4th gen 4.10 gears

Atilla the Fun

stock, or cammed? And we're getting off topic.

five7kid

iTrader: (14)

I could support this approach:

http://blogs.hotrod.com/video-jeff-m...l-a-24857.html

Apeiron

Pole position in the 1952 Indy 500 http://image.dieselpowermag.com/f/10...2_indy_500.jpg

lunati397

https://www.thirdgen.org/forums/engi...dgen-swap.html

Had the same idea making it fit suprisingly the duramax fits pretty good with out major mods also taked to a tuner and with a lift pump and tune he should get me in the 600s for hp and 12-1300s for tq

they did this in a 96 mustang awhile ago and it got 36 mpg and ran consistant 9.8 in the 1/4 mile

I hope to be up and running by the end of the summer most of it is cash flow for parts but its coming along and what I cant buy or trade for I build

Atilla the Fun

Thanks, I'm familiar with that Mustang, and I've studied your Dmax thread. I'm pretty sure the 6.2 can easily do 36 MPG, on a $500 budget. Neither of us will be technically legal under federal law, however. And neither of us would ever see 49 MPG. So I'm looking at the Jetta diesel, and it's no more suitable for towing than my 6.2 is. Thus I need to put it in something other than my T/A, since my T/A now has the hitches and the full-float 8-lug Dana 60. My ideal build is a six speed manual behind the WV oil-burner, I'm looking into this. The '83 Berlinetta has a good title, no liens, never crashed, and no rust. What more could I ask?

lunati397

I was thinking about shortening the 2500 rear and haveing the 8 lug out back but I think ill go with a 9 inch my budget is around 4000 to include wheels tires suspension and the tuner and pump for the duramax 1500 with just those

I cant wait to fill it up and have someone come running up to me yelling THATS DIESEL LOL

Atilla the Fun

The D60 was a direct bolt-in, width-wise. Mine was totally free, but any yard will sell you one for $150, maybe $200 at most. Mine was a '78 Dodge D200. Fabricating the torque arm bracket took me about 3 hours with normal hand tools, an angle grinder, a drill, and a stick welder. I have a stronger ring gear than a 9", with 2 more bolts, and that means stronger. Yes, you can get 40-spline axles for a 9", but the cost!!!!! I can convert from 30-spline to 35 spline for $300 more than the cost of getting a 35-spline diff to start with. I had to cut the trailing arm brackets, spring perches / panhard bracket off my 7.5, being sure I cut exactly 1/4" off to fit the larger tubes, but from there it was easy. No need to make a production of it, anyone can be driving a Dana 60 for under $450. Figuring 2 new e-brake cables, the conversion u-joint, and 2 brake fitting adapters. Wheels are from my '79 C-20. Excellent offset for using 225/60R16 And there is just room for 16x6" dually wheels with 5" BS, using 215/65 or maybe 215/60 if you like them short. I scored a cherry set of 3.54:1s off pirate4x4 for $30 shipped. Can you do a similar 9" on this budget? If so, it would allow taller gearing. If not, what's the cost of fuel, spread out over time, versus the cost of parts, all at once? Or the cost of interest on a credit card?