1992 Caprice Station Wagon 305 V8 vs 6.2 Liter Diesel

[vacationtime247]

Sold my 1999 Oldsmobile Alero for $1350. Found a 1992 Chevrolet Caprice station wagon for $1k. Has the 2.73 Rear gears, 700R4 transmission and a 305 gas V8.

Like the Caprice wagons, they don't have the additional glass top, it's smooth. The luggage rack is coming off. Last owner was smart and moved the sliders to the rear, but left on. He claims 24 mpg on the highway. Kind of a redneck ecomodder himself. He had a small boxy Ford ranger truck with a diesel engine in it. He had just purchased a 1992 Oldsmobile Custom Cruiser to replace the wagon he was selling. Owner put on a custom cruiser grill on this caprice wagon. Like it 'cause it has something of a grill block there instead of open.

Have a 6.2 Diesel engine from a 1982 Chevy truck in the garage. Know the diesel engine will get me much better fuel mileage. I'm hoping for 30 mpg + highway. Believe this is achievable. Because, the rear axle ratio combined with a 700R4 overdrive trans will allow for low RPM cruising yet still have ample torque to maintain 65-70 mph on the interstate. Think this is achievable? Have until summer to complete this project, using it for our travel car.

Hope to have no more than $2k in it by the time it's done. Will need to wire in a push button relay switch for the glow plugs, route oil cooler lines, get new exhaust put on for the diesel, mount a fuel filter and inline pump. Shouldn't be to hard of a swap.
VT247

[NHRABill]

24mpg might not be too far off for these 4,000lbs+ monsters being pre 1993 it is Tbi injected and I have a friend who is major into these wagons he has 3 and I get to do all the work for him. Don't want to hijack you too much but he gets mid 20's with his custom roadmaster that has the 350 motor that I lowered and modded for him.

you might have issues with your plans. I have his 92 caprice in my driveway right now has the (305 motor) I started taking the trans out today. Some genius replaced the 4l60 that these come with to a 4l60e this made the computer tell the trans to go into full lockup and the speedo to run at 150mph when you were going 10. I picked up a proper non electronic 4l60 for this and will get it installed if it doesn't rain tomorrow or if he didn't modify too much to get the other trans in there. 1993 and up they went to the 4l60E this cars computer is very picky.

If you pitch the computer and all pulled the 4l60 and replaced with a 2wd 700 from a camaro/ firebird from the 80's it should work but from what I read and researched the 4l60 was only a 3 year deal in these cars. There are 3 sensors on these cars all can be seen front he drivers side one on the rear differential one 2 wire back of trans speedo (gear) and a 4 wire plug just behind the linkage. The E model trans switched from a plastic gear speedo to electronic magnetic spark VSS this is what makes it tough. the car is setup even the base 4l60 non E for electronics only reals switch was the speedo gear readout so if you keep your original more I think of it you will have issues.

I hope I am wrong and encourage you to do your homework also I posted a few photos for inspiration these cars can look cool with a little work. This one below is actually a roadmaster funeral home Flower car with a fiberglass hood Impala SS grille flowmaster custom exhaust a very well tuned engine with a few tweaks I made for it. It does average 25mpg according to owner he clocks it when he does his 500+ mile drives every couple months.

My take on it lighten the load these are pigs big weight inside trim down the engine do normal ecomod stuff and clean her up make it look cool. You may even have the baby 4.3 V8 in there yes it came with a tiny 8. Shoot for 30mpg in a monster of a ride that would be cool.

[slowmover]

Step One, for me, would be to load the car as if for travel and weigh it. Not much point to a wagon if it can't do the job. Step Two would be to make comparisons to the trucks that engine came in: Play with calculators about tire height/gear ratio/torque convertor stall/trans ratios etc. in regards to engine power graphs according to anticipated travel speed.

And find out if that rear axle is up to the job.

.

[Big Dave]

This is a doable project.

There used to be a cat around here that transplanted a 6.2 into a Cadillac Fleetwood of similar vintage. He couldn't shoehorn a turbo under the hood but for a pure MPG-mobile the NA engine will work just fine. I know he is active on the 62-65dieselpage.

Do yourself an immense favor and modify the car to use a manual transmission. As strange as it seems, these underpowered engines eat automatics like teenagers eat potato chips. I had a 6.2 in a pickup and it went through five 700 R4s and two TH400s over the course of 305,000 miles.

You are aiming to reduce engine speed at a given road speed and that means the TC doesn't get enough fluid flow to cool it. Expect spectacular failures (parts scattered along the road) at interstate speeds.

The stick eliminates that possibility, and also eliminates a layer of electronic complication.

The stick will easily gain you 2-3 MPG.

Check out the impalassforum. they have links and complete project guide on converting B-Bodies to use Tremec T-56 six-speed. A supplier called F2B makes a conversion kit.

With your gearing, the T-56 has too much overdrive. I'd recommend a Richmond Gear 4+1. It's top gear is 1:1 which should be about perfect.

You'll need to upgrade your soundproofing. the 6.2 is efficient but noisy.

I think you could realize a 38 MPG station wagon. Maybe more as the stick will let you aggressively hypermile.

[pete c]

Dave, Wouldn't a monster sized tranny cooler take care of overheating issues? Also, it sounds like he's looking for a highway cruiser, meaning extended periods at speed with the torque converter locked. Assuming he's not pulling a heavy trailer up hills, I would think the 700R4 was up to it.

Just get that cooler and a tranny temp gauge as cheap insurance.

[Big Dave]

My old 6.2 truck had a tranny cooler about a third the size of the radiator.

All my tranny disasters came when the truck was cruising down the superslab.

In a way, locked-TC is the worst condition. The TC (with no relative motion between rotor and stator) is pumping zero fluid through the cooler. I understand newer automatics transmissions have an auxiliary fluid cooler pump.

Nothing cruises the slab like a stick.

The 700R4 is notorious for "hunting." In and out of TC lockup.

[vacationtime247]

Thanks to everyone. Some of the points and ideas wasn't something I'd considered.
The diesel should run at the same rpm as the gas engine. The transmission will be a 700R4 transmission with a large trans cooler. Figure out a reliable way to run the torque converter lock. Don't think I can use an aftermarket lockup kit because the engine will be a diesel and the vacuum would be wrong. Using a manual trans is way to much work and would send the cost of the build over the top of my $2k budget. But, it would be sweet!

Found this while reading on how to find the right 700R4 and wire it right.
""I've got converter lockup controlled by a 4th gear pressure switch along with a manual switch. It is disconnected by the brake switch, AND the TPS (throttle position switch) on the injection pump. If you are converting your truck from the TH400, over to the 700R4/4L60 - I sugest you remove your VRV from the injection pump, and install a TPS switch. This way, when ever you take your foot of the "gas pedal", the converter cannot lock. It's a nice feature. ""

Not sure how the 700R4 was hooked to the 6.2 that I have. Used the trans on an IROC project here while back. Will get a 700R4 and hook it to the engine prior to install. Have everything ready to drop in before I even begin. Guess I'll make a list here so I can use it as a guide.
700R4 @$100-200
Diesel Torque converter @$200
Engine oil cooler $50
Fuel filter and mount $75
Exhaust hung and installed $200
Misc parts $275
Hopefully keep within budget. Biggest battle isn't the install of the diesel into the car. It's convincing the wife it's a good idea! She thinks the Durango is nice and comfy. I hate it! 16-18 MPG just plain sucks! The wagon actually has more room, gets better mileage and drives better. She's not sold on the idea yet. But she'll come around. If nothing else, I'll cut the top off it like the Roadmaster Wagon. She really hated that one. Wouldn't even ride in it! Come on babe, it's a convertible! (Imagine an el camino like station wagon cut from the front glass and the bottom pillars with a sawzall/no top) Not fond of the Kammback on the Tempo either. Can't understand why?
VT247

[oil pan 4]

Yeah that drive train combo will work.
My 3 ton suburban had the 6.2L, TH700R4 and 3.08 rear gears.
Going from 3.08 to 2.73 is only like a 16% difference. That boat is about 2/3 the weight of my suburban and has aerodynamics that are about 1000 times better.

[cfg83]

vacationtime247 -

I'm hoping for great success! I saw one a few months ago with relatively low miles. It would be so cool to have all that room for trips.

CarloSW2

[vacationtime247]

Done pulling the motor. My hands are filthy dirty right now. Here are a few pics on the progress.