Diesel engine success in our G cars..

[Regal_Nut_84]

The problem with this idea is the cost issue. To save gas or pay less at the pump, its obviously a terrible idea. *snip* 33mpg is bullshit btw.

I'm not dead set on this, and I'm simply looking for better fuel economy. I know diesel is more expensive, but 30 mpg for $6.00 sounds a little better than 20 for $5.00. I think what I read about 33 mpg with a 6.2 was with a 200-4R in an S-10.

I don't necessarily care if it's a speed demon, but I do want it to get out of its own way. If it will have pretty much the same power of the 4.1 with better fuel economy, I'll be satisfied. I've also considered an SC3800 swap, but if the 4.1 can top 25 with a proper tune, I might just leave it alone.

What I don't understand is why you think the 6.2 wouldn't top 25 mpg with overdrive in a mid-size car. Not to argue, but I have read EPA estimates of 29 mpg highway with a 5.7 Delta 88 Olds diesel. My uncle also has a 93 GMC 2500 6.2L with over 300k miles that gets 28 mpg on straight diesel, and he doesn't even take care of it. He's the kind of guy that will spend $10 to save 10 cents over doing something the right way, like mixing 16% gasoline with his veggie oil and dumping it straight into the main tank with no heater. It gets 21 on his veg-gas oil. I'm just patiently waiting for his injector pump and pistons to fly apart.

I have personally gotten 25 mpg cruising at 80 mph with a 3.8 Regal, 200-C and 2.41 gears. Granted the 6.2 is about 65% bigger, but bigger engines don't work as hard, and with an overdrive, I would imagine it should do better than 25, if it gets 28 mpg in a heavy pickup with lower gears?

Stiffer front springs and some suspension mods will be needed, the 6.2 is a LOT heavier than whats in the car now. You won't get 33 mpg and should be happy with 20mpg.

I am wondering if I can simply order a new set of front springs for a 5.7L diesel Regal? Was the 5.7 about the same weight as a 6.2?

Anybody have an idea as to which Gbodies had the RWD V6 diesels in them?

If I'm not mistaken, I think they were only offered in the Cutlass and Regal, I have never seen a Grand Prix or Monte Carlo with either one. According to what I've found with Regals, the 4.3 diesel was only available in the base model, if you had a Limited, it got the 5.7. Strange. :shock:

Some things to keep in mind about diesels

1) they drive like dogs more because of the gearing than the engine. MUCH more
2) the newer ones dont have the greatest MPG, due to emissions. All of that is in the computer programming---its easily changed. The only other limits are injector nozzle and turbo size.
3) diesels dont care about weight

I am curious what gearing would be best if I were to build the 200-4R to accommodate? As to computer programming, the 6.2 I have is the first model year, no computer to it at all, it is completely mechanical. And when you say diesels don't care about weight, are you saying that less weight will not help economy, or are you saying that more weight will not matter?

I ran V6 diesel for year as a beater car . Could beat about any MPG in a gas car of same size today big time . Also Had V8 in the 98's . Hey 10 MPG more in a car is a big thing . 403 got 20 Plus the same in fuel form almost 30 mpg on trips. Loved the V6 by the way . Wish got more than 200000 miles out of it tho.

I am curious, what kind of fuel economy did your 4.3 V6 diesel get?

 

[MR442]

I got 30 MPG Plus with ease I live in country . And 43 Mpg best Running flats out west (air plane gears ) . I put lower gears in still got 30 MPG beating it for work . Compare to 22 MPG ON gas Job my parents had at time .

So they r not hot rods . If we want daily drivers and MPG . Its fine with me . Wish they would build something again ,

You can always have a real rod for weekend .

 

[Regal_Nut_84]

I got 30 MPG Plus with ease I live in country. And 43 Mpg best Running flats out west (air plane gears ). I put lower gears in still got 30 MPG beating it for work. Compare to 22 MPG on gas Job my parents had at time. So they r not hot rods. If we want daily drivers and MPG. Its fine with me. Wish they would build something again. You can always have a real rod for weekend .

WOW. Far beyond what I hoped. 😀 If I'm not mistaken, the Olds diesels got 2.29 gears with the 200-C? I'm thinking my car has 3.23s or 3.42s -- I'm guessing overdrive will be about the same cruising RPM...

 

[Regal_Nut_84]

The diesel V6 was only available in '83-'84 I believe, and I think by '85 they were both gone.

Close. I went back and looked. The 4.3 was offered only through '84. '85 still offered the 5.7.

 

[megaladon6]

Dropping a 1000lbs off the vehicles weight wont improve MPG much with a diesel, or rather any change under 1000lbs. So whatever a 6.2 gets in a small truck is about what youd get in the car
for gearing with a 200-4r i think 3.08 would be good. Youll have good acceleration and great highway cruising.
actually the diesel might be just over idle at 60mph!
(And before someone recommends the the 700r4. NO! You want the lower (numerical) gear of the 200 due to the high torque of the diesel)

 

[MR442]

A 85 98 Olds got 26 MPG I remember cause was double What A 350 equipped got I had at time.

THe lighter weight Idea is off . A 305 in a car can get 24 MPG and in truck 2wd only 18 MPG Weight does play factory . I haul tools in truck bed all time. When empty I can Gain Over mpg

 

[megaladon6]

Thats a 305---a GAS engine. We are discussing diesels.
When i drove diesel trucks it didnt make a real difference whether or not it was loaded. Though when towing a large load there was a bit of a drop.

 

[dogsht]

I think what he is saying is that plus or minus a thousand pounds won't affect a diesel mileage or acceleration rate near as much as it would a gas motor. With .67 overdrive the final drive ratio 3.42, 3.23, & 3.08 equals 2.29, 2.16 & 2.06! A 2.06 may bog your engine on rolling hills.

Don't forget the value of a working lock up converter. It's worth up to 1 1/2 mpg hwy and keeps a lot of heat out of your transmission and if your trans is partially cooled by your radiator then it helps take some load off your cooling system as well.

 

[Regal_Nut_84]

Dropping a 1000lbs off the vehicles weight wont improve MPG much with a diesel, or rather any change under 1000lbs. So whatever a 6.2 gets in a small truck is about what youd get in the car. For gearing with a 200-4r I think 3.08 would be good. Youll have good acceleration and great highway cruising.actually the diesel might be just over idle at 60mph!

Cool... So if my car already has 3.23s or 3.42s, it's a perfect candidate for it. I think 3.08s might be a bit tall, even with the extra torque. Even the 6.2 might lug a bit at idle. I've found several cars on YouTube that were 6.2 swapped and the owners seemed quite happy with them. No economy numbers though. I'm sure if a Olds Cutlass diesel 4.3 gets between 30 and 40, a 6.2 ought to fare similarly with the right gearing, as it will work nowhere near as hard as the 4.3. I'm quite encouraged in my research thus far.

(And before someone recommends the the 700r4. NO! You want the lower (numerical) gear of the 200 due to the high torque of the diesel)

700-R-Junk? I have yet to see one hold up for any length of time. If I ever have anything with one again, it's getting dumped for a 3-speed at the first sign of trouble. I've owned three S-trucks that had them. The first burned up a rebuild 4 times within 90 days, the second burned up 3 different transmissions in less than a year, and the third burned up within a month after I sold it, and I didn't even put 5000 miles on it. I've never owned anything with a 200-4R, which is why I'm curious about reworking for the diesel swap. I think you are on to something about the lower gearing of the 200, I think that is part of why the 700-R-Junk doesn't usually last behind a 6.2.

Couple of other thoughts I had, in order to have the TCC work normally, I am going to have to leave the 4.1's ECM and wiring in place, at least for that part. The 6.2 doesn't need any kind of connection to the ECM to run, but I am curious if the ECM will need input from the 6.2 in order to control the lockup? I believe these are simply locked and unlocked at and below 45 mph and under braking. I believe the 80s cars had a cable driven speed sensor in order to tell the computer the vehicle speed, I am guessing this is somewhere in the dash and will not be affected by swapping engines. But is that all there is to it? Just wondering if it needs an engine rpm input as well (this is usually gotten from the distributor's ignition module) to determine when. Getting tach signal from a diesel is a whole other ball of wax.

The other question involves braking assist. Is it possible to get a normal vacuum source from a diesel in order to operate a standard vacuum booster like in my Regal? Or am I going to have to adapt a hydroboost system like the donor motorhome has? If so, no big deal, Astro and Safari vans have a unit suitable for adaptation. Would rather keep my vacuum assist brakes though, less work.

 

[custom442]

it isn't as much an issue with the size of the vehicle, our cars are about as aerodynamic as mid 90s trucks, and some of 2wd duramaxes returning mid-high 20's mpg are surprisingly light, just under 4000lbs and use the nv4500, no one uses 1st granny low unless hauling and hypermilling guys with em I'm sure are skipping gears. Also keep in mind these trucks are used a lot in long travel and highway mileage, so most guys will say they have higher mpg on average...get it in the city and it drops significantly. I'm not aware of any early 80's or auto diesel trucks getting extreme mileage. late 80's early 90's rwd 2500 can be just over the weight of our cars, which most people are surprised with. S-10s can weigh 500-600lbs less than our cars stock for stock and have about the same frontal area. Like someone else said the gearing behind the 6.2 will affect mileage the most, and a lot of trucks with them have around 30 inch+ tires which we don't. There is a big difference in tuning from the factory between early 80's and early 90's trucks. I'm basically taking an educated guess it won't be over 25mpg, a lot of work and money for not much return is all I'm trying to get across. I'm sure if your car was well tuned now it would get over 20mpg easily. If you get 33mpg then come back and call me an *ss. It is a cool idea though and I'd like to see it happen.

I was confused since I thought this swap was geared toward performance + mileage.

Megaladon won't agree with me here, but that 4.1 2004r you have isn't going to be as strong as a 4 speed auto that came behind these beasts. They're not at all reliable but there will be less $$ in a purpose built 700 then a v6 2004r. I'd grab the transmission in the van or take it easy on your old 200 till you can have it built to spec. The TCC switch is done by vacuum and a 12 volt switched source I do believe, do some googling. You should be okay with hooking up to manifold vacuum from the 6.2, can find out real quick if its slipping in 4th though.

The rear won't last either if stepping on it but you're aware of that. Lot of modification to the fuel system. Have a feeling it won't go anywhere very fast in stock form. You can make them really fly though if you want

Could try v8 springs from the junkyard and if they don't work a stiffer spring from moog.