94 Caprice Wagon 5.7L project--46 MPG so far

[He-man]

Nice work. The 5.7L is a surprisingly efficient engine even though it uses very old tech. I regularly get over 30 mpg in my C5 Corvette and that is stock other than aftermarket exhaust.

[Frank Lee]

The Jed: you have reminded me of these:

[The_Jed]

Lol.

My sad attempt at post whoring.

[Vigo]

Impressive build, i'm really enjoying this thread.

As far as swapping the axles out, my first thought would be to use a rwd transfer case with a very mild low range (~2:1) and no front driveshaft. With your current tire size, 5th gear, and rear gear, a ~2:1 low range would have you doing about 2000rpm @ 55 mph, which sounds ideal for towing since you'll have abundant torque and probably not want to go much faster anyway. I'm not sure how this would fit under the car, but without a front driveshaft to worry about you could probably rotate it to suit with a little work. Seems like a more permanent solution than a 'theoretically quick'-change rearend. If you only used it rarely you wouldn't even need to make the shifter very convenient. Even jacking up the car and shifting the T-case by hand would be less effort than a rearend change, by far. I know you've already considered this but unless it requires a completely different main case for the nv3500 or major floorboard mods, it seems like the simplest long-term solution to me.

I'm also curious if you've recorded any highway travel with no P&G or EOC and what it does under more or less 'normal' steady-state highway driving?

Thanks for sharing this build!

[serialk11r]

Originally Posted by roflwaffle

A 5.3L running on 4 cylinder (~2.6+L?) might be a bigger jump. I'm guessing your car maybe requires ~25hp at 55mph, and your LT1 makes ~80hp at 1k rpm, which puts you at ~30% load.

Corvette C7 LT1 vs Our LS3 dyno graphs - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com

Going to ~60% load might make low speed cruising a lot more efficient if you can tolerate how the engine runs with AFM on.

http://www.tulatech.com/uploads/7/5/...13-01-0359.pdf

Wrong LT1, this is the old LT1, which is a little smaller and makes a bit less power, probably more like a bit under 70hp.

@ the OP, this is amazing and inspirational. I cannot believe you went with manual steering on that car...makes me feel like a wimp for struggling to turn my steering wheel with the engine off. If I were you though, I'd just go with a 2.74 final drive instead of the transfer case or a swappable diff, because your rpms are so low that you might actually do better P&Ging at a higher rpm. As you mention, you are already using 5th gear to pulse, why not just have 6th gear be like 5th and get a shorter 1st at the same time?

I kind of want one of the European gas guzzling V8 sports cars someday, if I can break 30mpg in one of those I'd be super happy already, nevermind 40.

[niky]

Damn. I missed this thread when it first came out.

46 mpg on a Caprice is wild. Believable, but wild. Love the looks of those wagons, I just wish we had them here!

[ChewChewTrain]

Originally Posted by funkhoss

Thanks!

The tires are at about 46 psi. Sidewall max is 44.

It does slightly less than 1000 RPM at 55 MPH. So slightly less than 1090 at 60 and slightly less than 1273 at 70.

Impressive MPG with that V8!

Have you seen this?

https://cumminsengines.com/uploads/d...el_economy.pdf

[skipperj]

Awesome job my friend! I used to love those old Classic Caprice wagons.I had 2 of them. A 1983 and a 1984 police scale car.They both had 305 C.I. V8's.They weighed 4005 lbs.I could get 27-29 MPG on highway and about 15 city.

[autoarcheologist]

This is awesome! We just sold our 94 Roadmaster Estate Wagon. It replaced a 2004 Tahoe that only got 17 MPG freeway, but would actually get 12-13 towing.

The only long freeway trip we took with the Roadmaster without trailer we got a best tank of 20.9 MPG. But that was doing 80 through Utah and Idaho. Ours had the 2.93 towing gears which didn't help FE any, and no mods other than a tune up and removing the roof rack cross bars.

Did the S10 steering gear help the massive front end wander? Between the loose steering, and the massive rear overhang which made towing 5500 lbs a white knuckle ride we sold the trailer then the Roadmaster.

If you do decide to tow close to 5000 lbs you should firm up the rear suspension, a Panhard bar would be a great addition.

Now you make me want another, but u should instead see if we can get our Mercedes e320 wagon over 30MPG.

[LioNiNoiL]

Nice work Hoss, very nice.
Thirty-five years ago, I had an over/under/direct drive
auxilliary transmission in my old Jeep, made (I think)
by Gear Vendors (now defunct) that worked really well
for towing. It was a lot more convenient than swapping
pumpkins when I needed to pull a trailer.