With fuel prices going into orbit, what have the members on this site found that works to improve fuel mileage on our big beasties?
I've been running a Microsoft Excel spreadsheet on my 1995 FWB and she is putting out 14 to 17 city mpg depending on traffic and weather conditions.
The 14mpg is when there's a lot of warming up and defrosting in the driveway.
You guys in Florida wouldn't know much about that stuff.
The 17 is when I featherfoot it in town, but with the CPT Stage II 4L60E transmission, it's sometimes gets the better of me and I can't help myself :bigroll: so there goes the fuel mileage.
Road mileage is consistently 23 to 24 with one at 26. :eek:
I have no idea what brought that last one so high. But fill techniques don't vary, so I'm at a loss.
SO - - -
Are there any gadgets that can IMPROVE MILEAGE that are REALLY worthwhile?

I have been getting 18-18.8 mpg (LT1 Roadmaster wagon) on my daily drive that is mainly in stop and go traffic.

That is as best as these cars will do and it isn't bad IMO. I get better gas mileage in my LT1 wagon than my friend who has a V6 Honda Accord ;)

There are no "gadgets" that improve mileage. If there were, the automakers would use them. Improving mileage comes down to the basics: proper tire pressure, clean filters, proper tune, driving slow, accelerating slowly. I'm currently trying some "hypermiling" techniques - I'll let you know in a few days when I fill if they have made a difference.

There is a thread in here on performance tuning for mpg improvement. Check it out.

Jay,
The insurance company I was with some years ago, in cooperation with other groups and the Connecticut State Police, ran a bunch of tests to see what kind of driving actually saved gas for different size vehicles.
At that time, they were using CARBURETED and not fuel-injected cars.
The results were surprising.
Using the big engined state police interceptors, they found that moderately fast acceleration away from a stop actually saved fuel :eek:
This was NOT, repeat NOT squealing tires, but a decent move-out from a dead stop and certainly wasn't the little old lady type of crawl from a stop light.
On the other hand, the best mileage for ricers WAS THE CREEP AWAY FROM A STOP.
That was back in the early 1980s, so I don't know how that would play out today, but if you note how Elias is doing with his humongous wagon, he certainly isn't paying much of a penalty, nor am I for each of us lugging a 2-ton beastie around.
Furthermore, I'm using a high-slip torque converter behind the motor yet getting almost as good fuel mileage as Elias is getting.
One thing I do keep after, religiously, is tire pressure:
Maximum sidewall allowable at all times.
I've done this on every vehicle I ever had.
The thought of a soft tire "tucking under" in an emergency turn scares the hell out of me after I saw it happen once on a track when I was a corner worker and a car had hit debris and that soft tire slowly went out from under the racer.

I agree. Only thing else is to jettison weight. Take out the rear seat. Plastic fascia. Trunk liner. Spare tire. Split the headliner. Everything from the B pillar back. Empty out the whole of it. And you'll save money.

Ah ahha. Really, though. The number 1 way to save gas or get better MPG beyond the above suggestions is to shed some weight. If you had a truck, you could lose the tail gate. Only thing weighty or worth while enough to lose on a fwb is the spare. If you've got AAA or AARP (llike most Cadillac owner's ... tee hee) you'll be fine. Or go on a diet.

We're talking incidental savings. So it's really not worth it. At $80 a tank a few dollars isn't much of a concern.

Better to plan your trips, take less of them, car pool, and so on if saving $$$ on gas is a priority.

I've gotten 16 and 17mpg for mostly highway driving. Granted I am lead footing it at times (and constant A/C use in this heat), and driving between 80 and 90 but I'd still expect 20, no? The damn thing was rated at 25. Many, many cars can easily meet or exceed their EPA highway rating. Why not these cars?

I think something is up...but it's not the O2s. My BLMs are 128 +/- 5 on both banks, which is totally acceptable.

I was thinking EGR...or maybe something exotic like a Motorvac treatment, which isn't cheap.

I just did plugs, too. Used 96 LT1 double platinums. And that 16 was AFTER I got the coolant temps back inline and AFTER I did the plugs.

Kevin, I would bet that if you dropped to 65-70, you would see 20 without a problem. Try it for one full tank. I know how hard it is to slow down. I am a fast driver in the summer in my SS. Since gas has doubled, I have slowed. I only noticed how slow I was going for about a week. At first, it seemed REALLY slow. The most interesting thing is that it didn't really change my driving time...

I filled it up again after like 97% highway driving on this tank, though not a full tank (135 miles or so). I calculate about 18.7mpg, which is better. I also was hard on it at times on this drive so I dunno why it improved all of a sudden.

I will keep my eye on it and probably try an EGR valve and maybe solenoid. If the car is REALLY capable of 25 at 65 or 70, then 80-85 shouldn't kill 6mpg. But then is it really capable of 25?

It does seem to have some kinda weird low rpm uneven torque delivery. Hard to explain. Surge? Maybe. Probably below 1600rpm only. Knowing LT1s, it's probably just the opti talking...yay.

But then is it really capable of 25?

Sure is. When I first bought my Fleetwood I drove it to Miami, FL from Virginia and it made 26 mpg cruising between 65-75 mph.

My 1994 Roadmaster Limited with the 2.56 open gears had the most miles per gallon, it hit 28 mpg from Chicago to Indy and back.

My current '95 LT1 wagon makes 18-18.7 in mixed city/hwy driving... so you shouldn't be getthing those low numbers with pure highway driving. Are you sure it is hitting 4th gear?

It is absolutely in 4th. One thing that surprises me - it seems to unlock the TCC (or at least do some funky PWM to it) without much throttle application. It doesn't really seem nearly as capable of climbing hills in lockup as my 93 9C1, especially below 50 which is expected. But then that's the L05 and a factory 3.42 compared to 2.93. But even at higher speed it comes out at times when I think it shouldn't.

I did try adding some spark advance (only 2°) in certain areas like cruise. Engine didn't like it though and I ended up taking more away as knock retard. I'd think I could at least add a measly 2° even running 87 octane. I am sure there's some carbon in there that I need to take care of. KR is quite rare running the factory spark advance at least. I just always thought of the tune as conservative, even for 87 octane.

[QUOTE=kevm14;1542614]If the car is REALLY capable of 25 at 65 or 70, then 80-85 shouldn't kill 6mpg. QUOTE]

I would say with certainty that it would. Do the one full tank slow drive, and let's see...

Well I ran some simple numbers.

(85/70)^3 = 1.79. 79% more power is needed to maintain 85 as it takes to maintain 70. But this can't directly translate into mpg because 25/1.79 = 14mpg. I guess it's too complicated for simple math since there are other factors not accounted for like decreased pumping losses with more throttle input, higher rpm which may effect efficiency (for better or for worse, depending). Hmm.

Frontal area, coefficient of drag, rolling resistance... others to think about.

Good math on the power requirements. I've read stuff on the cars that do Bonneville, and the HP needed to push a car past 200 is astounding. The jump from 175 to 200 is huge.

I will have to baseline the car in some way that is repeatable. This A/C use isn't helping, but in my experience with my 9C1, A/C use was actually not trackable based purely on mpg. Not to mention more efficient than driving with the windows down (and way more comfortable). Maybe that'll be different in this car for some reason.

Oh, how about MAF airflow. Maybe some members can get some MAF g/sec vs speed (flat road required or at least get the numbers for both ways). MAF airflow should directly translate into fuel usage. Well MAF and long term fuel trims (BLMs).

On those "commutes" from Hartford to Walpole, MA to Tufts doggy hospital, across i-84 and the Mass Turnpike with cruise control set at 72 (no cop bait), that's when the '95 FWB was showing a consistent 23mpg.
But I couldn't come anywhere near Elias's mpg since his run from Chicago to Indianapolis and back is on virtually pool-table-flat roads while the stuff I was on is nearly all up and down, rolling, New England hills, with lots of jerkoff drivers squatting in the left lane :mad2:(of 3) going 50.

I'm not sure about improving MPG, but if it helps, my small '84 Chevy is rated at 20 something city and living on Long Island commute I still only get around 21mpg (lucky) and I keep it properly tuned. My commute is 85% parkway... I'm not sure if I've owned a car yet that reaches the EPA mark for highway driving. (I'm currently on my 5th car) Perhaps it's just my mix of highway and "city" driving that does this?

My 96 has been getting 23mpg since the weather warmed on my daily commute of 26 miles mostly highway. It does have some mods though. CAI, Flowmasters, performance program. Keep the tires at 40lbs as well. Also have the backseats removed at the moment so a little less weight. Never dropped below 20 even on the coldest months and I got 27mpg with it on my last trip to see my daughter in EauClaire. 60 miles mostly freeway. I could not be happier with the mileage you can get out of these beasts. Thinking of pulling spare and carrying around a can of fix-a-flat for awhile just to see what I can max it (mpg) out at. Oh, and Ive been driving like a grandpa as well. Hard to do with that much snap under the hood.

I would look at exhaust improvements (them mufflers are chokers, and the highly bent up crimped pipes) and a PCM tune, and maybe play a tad with the rocker arm adjustment, Setting it to GM spec will effectively make the cam slightly smaller, therby moving powerband down, but if you go looser (you'll probably need locking nuts like poly locks or Kool Nuts) like 1/4 turn down, you make the cam slightly larger and move the powerband up in rpm. You are talking 250 rpm range for that, around 2-4 degrees duration on the cam tops.

It makes a diff for sure.

Lose weight (you included with the car! :) Leave the spare at home and carry a can of fix a flat...

Go single exhaust and make it one big pipe.... Make sure you have the aluminum rims too. Rotating weight makes a diff. Maybe some taller tires to raise the gear (lower numerically), but it adds rotating weight.

You wanna cruise at peak torque for best BSFC, but that is often higher in rpm. But is very efficient for that rpm and power made, very very efficient.

PCM tuning can really help. Add the Performance Mode switch for the LT1 cars and newer. And set it up for economy and performance so you have best of both worlds.

Shifting right probably has more diff on things. You have gears, use them to move the car, don't make the engine lug to move the car and you will find you backing off the gas a lot more. But keep cruise rpm low as you can (hence why we are getting 6 speed and 7 speed auto's now)

My 96 has been getting 23mpg since the weather warmed on my daily commute of 26 miles mostly highway. It does have some mods though. CAI, Flowmasters, performance program. Keep the tires at 40lbs as well. Also have the backseats removed at the moment so a little less weight. Never dropped below 20 even on the coldest months and I got 27mpg with it on my last trip to see my daughter in EauClaire. 60 miles mostly freeway. I could not be happier with the mileage you can get out of these beasts. Thinking of pulling spare and carrying around a can of fix-a-flat for awhile just to see what I can max it (mpg) out at. Oh, and Ive been driving like a grandpa as well. Hard to do with that much snap under the hood.

I would be very happy with this mileage, as well. Is it a base FW with the 2.56 gears or a Brougham with the 2.93s?

If you worry about gas prices enough to remove your seats & spare.. then this is not the vehicle for you to drive daily!! :bonkers:

Good point! Hello!!

If you worry about gas prices enough to remove your seats & spare.. then this is not the vehicle for you to drive daily!! :bonkers:

Ive got the base with 2.56 rear end which given the mostly highway miles I drive helps my mileage as well. As far as my backseat being removed, its out cause Im upgrading my rear speakers. I plan on putting it back eventually. Im just having fun seeing how much I can squeeze out of her. I have to drive it daily since its my only car at the moment.

When I lived in Fla., I worked at a station which had two pole trucks that ran on propane. They had Intergational Engines with the conversion. I'm curious as to how propane would work on one of the Cadillac engines.

I have wondered too, a friend of mine says in India they are big at running CNG gas and he can't figure out why it isn't popular here. Other than no infrastructure, why not? No cold start issues, excellent emissions all the time, pain to store it, pain to pump it, it is a byproduct of gasoline production and often a waste byproduct (he used to work at a refinery).

There was an article on TV recently that stated Brazil's cars run mostly on natural gas. Of course the cars seen in the article were mostly compacts & subcompacts. Natuaral Gas being a true gas, I wonder how they induct it.
We use propane on our fork trucks, because you can't use gas engines inside an enclosed building. Propane is a liqified gas and has a low combustion temp. You can get frost bite if exposed to it for too long. If the fittings get frosty your skin will stick to them. That's why I always wear gloves when changing tanks. Not sure how Propane rates as a poluting fuel ( CO2? ), but it doesn't create a lot of carbon by products to contaminate the engines. The oil in the crankcases is clear whenever your check the level.

Actually most of Brazil runs on E100 Ethanol (aka, 100%, not the 85% we have here due to our cooler climate).

Yes, it is a gas and even at subzero temps, CNG and Propare as gaseous and that makes cold start a dream. And cold emissions nearly as good as hot if as good as. Engine oil lasts much longer too.

But the key is infrastructure. And of course in the US, they wanna tax you on it, so if you can get it now it is road tax free. Think of the jugs for your grill, they are around 5 gallons. For $11 at a place that refills them on the spot, probably cheaper if you have larger tanks. So nowdays that is pretty darn cheap!

But if you go to HomeDepot or Lowes or Local stores to buy a refilled one exchange, it is pretty expensive.

But the key is infrastructure. And of course in the US, they wanna tax you on it, so if you can get it now it is road tax free. Think of the jugs for your grill, they are around 5 gallons. For $11 at a place that refills them on the spot, probably cheaper if you have larger tanks. So nowdays that is pretty darn cheap!

But if you go to HomeDepot or Lowes or Local stores to buy a refilled one exchange, it is pretty expensive.


Our fork trucks use the little "Iron Duke" engine and they sometimes run constantly, 24/7, and are not driven in any conservative manner. I think our tanks are twenty # capacity, which will last about one day per tank. Figuring $40.00 per tank, that's not too bad. Of course, that little engine has about 1/4 the cu. in. of my 425.

Your right, those refilled exchanges are a rip-off.

Thinking about Elias's consistently better mileage than mine and how N0DIH mentioned that better exhaust pipes will certainly improve fuel mileage, has just about pushed me into replacing the stock exhaust system in the VERY near future.
Now it's a question of WHAT.
Elias originally had a Corsa system from a Caprice with a 9 inch extension added to compensate for the Fleetwood's added length that sounded really great. But N0DIH mentioned pipe sizes befitting a Kenworth, or so it seemed.
That last point has me concerned from the standpoint of wanting some peace and quiet on a long haul when we're towing the PopUp RV, so muffler choices become critical.
I'm open to any and all suggestions . . .:yup:

If you worry about gas prices enough to remove your seats & spare.. then this is not the vehicle for you to drive daily!! :bonkers:

True. I've never bothered, but you know what's going on with me in that regard lately.

Dad, the continual oddball, has been thinking too hard with his Roadmaster lately in the name of weight savings. I saw him tinkering with something in front, with the hood popped. What was he doing? Removed ONE of his TWO horns (those #'s being important), "because it's extra weight to drag around and I don't need two." Same thing, kind of, with his front bumperettes (which if you know the Roadmaster bumper, it isn't exactly a clean removal like the Fleetwood). He always wanted them gone, but now "they weren't feathers either on there". You know, big fuel mileage increases from removing 5 pounds:hmm:

But realizing it's worth far too little to ever get rid of, despite being a relative guzzler...that's his little game to appease himself.

Otherwise, tune up, loose extra junk, drive like an egg under the pedals, play with your PCM tune for economy, etc...there isn't a huge amount of much to do in this regard if you drive a tank, otherwise.

Well, Jim Hand had run mid 11's on 2.5" duals with Walker Dynomax 17749 mufflers. Don't waste $$ going beyond that. He is running a 473 CID Pontiac shifting around 5700 rpm. And when we went to 2.25" tail pipes to prove the concept that large tailpipes aren't needed, his mph (the measure of hp) slowed very slightly. ET didn't change. So yes, it affected things, but not radically. So stock 2.25" is probably fine for well into the 12's....

Elias originally had a Corsa system from a Caprice with a 9 inch extension added to compensate for the Fleetwood's added length that sounded really great.

The Fleetwood has the Borla 14504 system with CIA export pipes and CIA Tubular headers. It is a 2.5 inch system from the headers back. I do not drive it daily so I do not know the exact gas mileage.. it isn't great after the 3.73 gears.

My wagon on the other hand has stock manifolds, stock catalytic, Borla 14504 midpipes, Flowmaster 40 series muffers, no resonators, and Z28 tips. The wagon's gas mileage got better, but it is hard to tell if it was the exhaust because I also gave it a full tune up at the same time. I am getting 18-18.7 with mixed city/hwy right now. I do not drive like a grandma either! I enjoy these cars for what they are and if you keep them properly maintained and run good oil, you will be suprised at how well they do with respect to gas mileage & size. I will take my badass machine over a econobox anyday!

http://i203.photobucket.com/albums/aa306/96fleetwood/2363435476_9795862309.jpg

I will make a video of the two systems today. The Cadillac sounds clean, mean, and refined. The Wagon sounds like a big block chevy with attitude.

First off, the horn removal thing scares the hell out of me.
Back in 1977, I bought a PacerX with all the tricks; big, 258- 6, 4 speed, etc., but that was the days with the Ralph Nader inspired stuff like quiet horns (only one to be nice and quiet so as not to disturb the birdies or something).
So, one day I was coming back from work and an old gent was stopped at a stop sign, looking away from me.
I hit that beep-beep.
Nothing. He kept looking at the oncoming cars facing me and sure as hell, pulled out right IN FRONT OF ME.
Luckily I was only going about 20 and already had my foot over the brake and my other foot on the clutch.
When I stopped as he pulled out, my front bumper was about a yard from his driver's door as he went past.
His eyes were the size of baseballs and I think he needed a change of skivvies.
The moral is KEEP THE LOUDEST HORNS YOU CAN GET BUT USE THEM JUDICIOUSLY!:rant2:
The next day I installed those compact but shrill, Italian air horns behind the grille. They worked wonders on unconscious drivers. I wish I had them on the Fleetwood when some jerk refuses to look my way at a stop sign.
Now, as for new pipes:
Thanks Tom and Elias.
Looks like I'll go Elias's manifold and pipe setup and keep things quiet.
Hmmm. . .now to scrape up the dough:D

Old Fleetwood...you don't even have to tell me. He's a bit wacked, for sure. Still has one horn, which to him is fine and dandy.

Being that his '93 Fleetwood--the household spare car--is still lower mileage and much nicer overall than the Roadmaster, I continually have to make sure he does nothing of the sort to the Cadillac. Thankfully, he only took off the bumperettes and has left it at that...

Weird guy, just a weird guy at times:cookoo:

And as always weight out the cost of the mods, if it costs $1000 to do a mod, and it gives you 1 mpg improvement, then it is going to take you a LONG time to recover the investment.

But OTOH, doing something like PCM tune like I did to mine for running E85 and I can save $1.20 a gallon by using E85 and the high octane of the E85 and the high compression of the LT1 I only lose 2-4, 3 on average mpg. So honestly, it is the best "mpg" improvement. OR should I say, more cost effective way to run.

Now my 3800 SC, I am seeing more loss in mpg than the Cad, (8.5:1 compression vs 10:1) and no matter what I can do so far is not helping much. I am in the 16-20 range so far. Highway, seems closer to 20, but city is pretty bad. So I am trying to eval the cost and might go back to 93 octane. Or maybe a mix of 87 and E85 and see if that will work out.

Highway, seems closer to 20, but city is pretty bad. So I am trying to eval the cost and might go back to 93 octane. Or maybe a mix of 87 and E85 and see if that will work out.

So which did better with respect to fuel economy? The 4,477 lb Fleetwood or the 3,794 lb Park Avenue ;)

BTW, the exhaust modifications I put on my LT1 cars were for performance and sound, not in the hopes of better mpg.

I wonder what the K&N FIPK does for fuel economy, they claim it gives you ~2 mpg....

Can't dispute the economics of the pipe installation, but OMG the glorious sound!:cloud9:
As for the re-tune, I agree, fully. Then there's E85.
But like Willie Quiverstaff said hundreds of years ago in some play: "Aye, there's the rub!" As far as I can tell, there are ZERO E85 stations in Connecticut.:crying2:
So I'm back to square one with gasoline and will have to fiddle with tuning.
Therefore I'm open to suggestions regarding spark advance and other settings both for performance but with a heavy nod toward economy.
My last frame of reference in this area goes way, way back when I was stunned to see how fuel mileage skyrocketed when I advanced the timing on my Corvairs.
I guess GM was afraid that the average customer would damage the manual shift cars by lugging them in too low a gear and spark knock would hammer the pistons badly. Then warranty claims would pile up.
But tweaking the spark advance turned those motors from mild to wild surprisingly easily.

Well to date:

Best on gas (91 min octane needed for 3800 SC): 27.7
Bast on E85 3800 SC: 20.5
Average on gas: 24.5
Average on E85: 18.5-19
Worst on E85: 16.5

Best on gas LT1 Fleetwood w 3.08's or 3.42's, didn't change much: 22
Best on E85: 17.7
Average on gas: 19-19.5 (depends on time of the year)
Average on E85: 16.2
Worst on E85: 15.2

So on gas, the 3800 rocks, on E85, not that good. LT1 is much less affected by the E85, most likley due to the higher compression (10:1 vs 8.5:1).

I did gut my air box on the 3800 SC, that REALLY woke it up. But E85 mpg hasn't changed squat. Even highway is still in the 19's. It just doesn't do well on it.

So which did better with respect to fuel economy? The 4,477 lb Fleetwood or the 3,794 lb Park Avenue ;)

BTW, the exhaust modifications I put on my LT1 cars were for performance and sound, not in the hopes of better mpg.

I wonder what the K&N FIPK does for fuel economy, they claim it gives you ~2 mpg....

I setup a tune on a friend of mine's 94 FW with 2.93's and non tow package. He is claiming 18's on E85 highway (80+ mph) and 16.5 around town. He is happy with it. His only "mod" is a Vortec truck airfilter on the MAF and the air box lid removed trying to get underhood warm air. E85 likes the warm air ingestion a lot. But in reality, that doesn't make a diff on the LT1 cars, too much airflow though the underhood. It just doesn't make a diff. I know, I tried and tried and tried and couldn't get it to WARM UP underhood!

Wow, I have to say I am impressed with your Fleetwood. It has 200,000 more miles than the Park Avenue, and weights 1,000 lbs. more! :worship:

I can't complain at all. It still is my favorite car to drive. I do tend to like them all, wish the FW was just 1000 lbs lighter! Man would that be a rocketship. The traction control on the FW is far better than the Buick for sure. The Buick seems to do it via the PCM only, no brake apply, no throttle retard, simply timing and cyl cutting only and it doesn't do a good job. Maybe without the SC, but with, not a chance.

I reflashed the Cadillac yesterday and I'll see how it does. Taking most of my trans shifting stuff out and going to stock V4P with the gear change only and then lower the 3-4 shift to stock V4P. We'll see how it does now. It was feeling sorta sluggish in the lower rpm range, despite able to roast the tires at will. I did put on the stock air box and MAF again (was running SD) so maybe it is just the temp change for now. Still running E85 in it, it still runs great on it.

So if I go for those great sounds (okay so it's not for mileage, but I'll tell the wife it is) and go for a set up like the one that Elias has with headers and pipes.
Then:
> Improve the induction area with K&N goodies, again as Elias has done to see if that 2 mpg claim that K&N claims is true for the product.
> Go with pre-programmed chip according to what I spec it out?
or
> Go whole hog and go the route with the laptop and play games in the car on the road and experiment?
Thoughts?:stirpot:

You will end up spending more than you can ever make up.

Exhaust ~$800-2,000

K&N FIPK ~$200 or RAISS ~$400

PCM programming ~$175


I still have to make new vids, it was a busy weekend.

So I still can't pee and moan if I go whole hog and copycat Elias's exhaust and induction system, albeit I might have to do some fancy dancing re the family finances.
Then again, the Fleetwood is our "tow truck" for our PopUp RV, right?:sneaky:
And looking at what I've dumped into Big Blue so far, it isn't so bad:
> Original cost on eBay: $6,500.00
> Additional Inspection: $99.00
> Shipping, Plano, TX to W. Hfd.,CT: $950.00
> CPT Stage II Installed: ~ $2,000.00 (@Dealer)
> Total revamping of brakes for trailer tow + hitch:$1,550.00
Add to that about two large for other stuff like the instrument panel when the trans indicator went out and the BCM died and I don't think I did too badly to have a vehicle that gives:
> ZERO Fatigue on long trips.
> Forgets there's a 1,900 lb object attached to the trailer hitch.
> Acquits itself very well in most traffic light grand prixes (!)
> Will certainly OUTFIGHT any pissant econobox in a collision.:p
> Is certainly cheaper than buying anything new capable of doing what THIS vehicle will do !;)

Will advancing the timing make our cars more efficient? I read something on the matter years ago the premise being that cars aren't optimally timed for fuel savings to provide for better account of emission standards. Advance the timing = getting better MPG with worse emissions.

I haven't a clue. Anyone have any answers?

Yes, but you won't be able to go very far on 87 octane. In fact, mine wouldn't even accept 2° more in the highway cruise area without some recurring knock retard. And once the knock sensor speaks, the PCM ends up having to pull more timing than you started with to get a pinging engine to stop pinging. So you're better off running a slightly conservative tune. You're better off 2 or 3 degrees under "ideal" and staying out of knock retard than 5-8 degrees retarded, sporadically (which will feel uneven, for starters, not to mention killing power).

The real problem with spark tuning is that the engine responds differently depending on conditions. MOST conditions are accountable such as intake air temp and engine coolant temp, but engine load is not. And when I say engine load I don't mean manifold pressure, that's one of the axes in the spark tables. I mean the speed at which the engine can rev while under load. Here are two extremes to paint the picture: an engine free revving (like in neutral) will take a LOT of spark advance before pinging. However, that same spark advance that "worked fine" while free revving will ping like a bastard if you hold the rpms steady and add throttle (such as asking these cars to climb a long hill or tow or even just merge on the highway). Worst case is engine deceleration under throttle, such as during a WOT transmission shift. So you end up having to make it a lot more conservative in, say, 1st or 2nd gear, because in 3rd or 4th, you might have pinging and KR. This is also affected by what gear you are running. A lighter car and/or a steeper gear will accept more engine spark advance all things equal. This is one reason why you have to be careful when tuning an engine on a dyno, ESPECIALLY if it's an engine dyno. But even a chassis dyno might let the engine accelerate much faster than it would on the road. That's the short of it...in my case, I want to get all of the carbon deposits out of the heads and then see what it can take on 87. Following that, I might try a premium fuel tune.

How much gas can you really save by taking out a 50 pound spare out of a 4500 pound caddy...Just don't see it...

I have people tell me all the time not to carry a full load of water in my motor home cause it saves gas...Motor home is 12000 pounds and a extra 50 gallons of water is 415 pound (8.8 gallon) not much savings when taking the total weight...

No matter what it seems, it still takes a % more power (gasoline) to put that weight into motion and a % to take it out (brakes).

Talk to any drag racer, 100 lbs is 1/10th of a second down the quarter mile. Weight matters.

1600 places you can find and remove 1 oz is 100 lbs. Start shaving!

Is it dramatic? No, but go find excess bolts, spare tire, jack, etc, it all does add up and will start showing up on the mpg. Not gonna get you 5 mpg improvement, but nevertheless, improvements.

And on the RV, ditching 415 lbs of water, that might even translate into a few extra feet braking improvement and that is the difference between someones bumper and the back seat....

How much gas can you really save by taking out a 50 pound spare out of a 4500 pound caddy...Just don't see it...

I have people tell me all the time not to carry a full load of water in my motor home cause it saves gas...Motor home is 12000 pounds and a extra 50 gallons of water is 415 pound (8.8 gallon) not much savings when taking the total weight...

No matter what it seems, it still takes a % more power (gasoline) to put that weight into motion and a % to take it out (brakes).

Talk to any drag racer, 100 lbs is 1/10th of a second down the quarter mile. Weight matters.

1600 places you can find and remove 1 oz is 100 lbs. Start shaving!

Is it dramatic? No, but go find excess bolts, spare tire, jack, etc, it all does add up and will start showing up on the mpg. Not gonna get you 5 mpg improvement, but nevertheless, improvements.

And on the RV, ditching 415 lbs of water, that might even translate into a few extra feet braking improvement and that is the difference between someones bumper and the back seat....

GG. :o

Keeping the spare tire & related tools will save you $50-200.00 on a tow truck ;)

Leaving the spare and jack at home to get better mpg: 0.5 mpg
Having to call your wife to come get you 75 miles away when you get a flat: Painfull....:thepan::thepan::thepan::thepan:

Keeping the spare tire & related tools will save you $50-200.00 on a tow truck ;)

0.5 MPG is being pretty generous for a 50lb spare/lug wrench lol.

You all don't have AAA or AARP?

Gotta make it sound halfway good.... :)



0.5 MPG is being pretty generous for a 50lb spare/lug wrench lol.

LOL NODIH.

Truthfully, gas prices are only what, .30 or .40 cents a gallon higher this summer over last summer. I don't see what all the panic is. ...what does that amount to, $7 or $8 more a tankful. Even if prices were this high all year long, what's that? $500 or $600 a year more than last year. Ok. That's not exactly going to break the bank or send me to the poorhouse and I don't figure it's going to do the same for MOST everybody else with these cars.

I won't be stripping my Caddy down like a cargo van and dumping the spare just to save a few hundred bucks. :)

The BEST way to save gas is to "ride" with your friends!!!

For me, I am upwards of spending $450 a month in fuel, JUST to get to work and back, and that is after switching to a car that gets better mpg (28 mpg). I am driving 750 miles a week, work only, 28 mpg, which is only a paltry 23 gallons, and I am spending around $4.359 a gallon (93 octane). That adds up big time. So if it goes to $8 a gallon? I will likey be forced out of my job or out on the streets, because the rent won't be ABLE to be paid. I am trying to work from home if I can, but it doesn't work out well, I just need to be there.

If I drive my "short" drive, only 650 miles a week, my mpg drops to 22-23 due to the city driving. Which makes it not cost effective to drive, heck, the Fleetwood on E85 is cheaper to drive at that point!

I was trying to get E85 working, but honestly, the car is really suffering in mpg with E85 over gas. But I may have to go back to it, it is STILL cheaper depsite the 8-10 drop in mpg, the costs are too hard to ignore depsite the environmental issues.

Yes, it is a real problem for me. But no stripping the car down, I am doing what I can in the tune and avoiding back roads...

For me, tuning, I will do what I can. But not much helps that much, but I have seen upwards 30.6 on one trip driving 70 mph.... I am trying!

I was BIG on E85 years ago but it's not as cheap as it used to be and I just got awful MPG with that stuff. Used to use it in my Tahoe when I could find it on long trips. Here in FL there's only a handful of stations with it.

What you will find here, is gas blended with as much as 10% ethanol being sold as regular unleaded. It's no cheaper. And is like adding mixer in a drink - better for the house, wink, wink. Worse off, some stations have even been found pushing it with as much ethanol as E85!! There was a rampant rash of that going on here in Orlando a few months ago. All kinds of people with non E85 compatible cars were reporting problems.

I don't have any answers. I'd like to see more sources of oil tapped, new and old. Everybody wants to sink a well and strike it rich. There's lots of oil left in the ground that could be processed. E85 competes with food and that bothers me some - not enough of it comes with post consumer waste. And what of lost technologies? I'd like to see advancements in steam technology, a modern adaptation of the Stanly Steamer. And so on.

Yea, you've got one hell of a commute NODIH. Haven't done that much driving since college - 180 miles a day back then. I know you talked about this some awhile ago. Your best bet is to get a used Honda Civic, Geo, or Aspire for your commute. Keep your Caddy for the weekend.

Wow, 30.6 miles per gallon from a supercharged 3800.. that is amazing.

You really need to move closer to your job or find a job closer to you. That drive is insane, especially with the traffic around here. I would go crazy if I had to deal with Chicagoland traffic for that long per day.

Yup, I am getting pretty sick of the drive, so far with so many idiots on the road.... Been doing it since Nov 18, 2002, not that I am counting....

30.6 was holding 60-70 in traffic, cruise as much as I could from Rockford to the 53/I90 interchange @ Woodfield. I think I was down to 29.2 by the time I got to work in Libertyville. Still not bad for 75 miles to do it. I am generally getting in the 28-29 range highway if I baby it. But if I take 120 across though Volo to Rockford that way, 22-24 if I am lucky, with E85 I was down to 16, which is what the Fleetwood LT1 gets on E85 on the same drive with a 350 V8 and 5000 lbs with me, fuel and junk.... Sheesh! 3800's love E85 under boost, but not for economy.... Sucks there. I might play more, but for now, I am back on gas.

I am doing my own tuning on the 3800, it is something somewhat diff than the LT1, but I still like the LT1's brute power, the 3800 SC does pull good, just about everywhere too. I wouldn't wanna race the 3800 vs the LT1, at this point with the tune, I would probably have to put my $$ on the 3800.... The upper rpm pull is great. AND it has power downstairs, IF you can hook, no matter what, it is still a roots blower.... :)

Wow, 30.6 miles per gallon from a supercharged 3800.. that is amazing.

You really need to move closer to your job or find a job closer to you. That drive is insane, especially with the traffic around here. I would go crazy if I had to deal with Chicagoland traffic for that long per day.

The E85 here is $2.799 still, for now, but most stations have jumped up in the mid $3 range. Really, the flexfuel vehicles are a compromise, I could do better on mpg on them for E85, would love to get one to tune.... But the whole fuel thing is really frustrating. Something is going to have to give. It is ridiculous what is going on right now.

Time to make my own fuel, IF I had the time....

I need to really start pushing to look, but so far there just isn't much in the market for good tech jobs where I live. I guess time to make my own company eh? :)



I was BIG on E85 years ago but it's not as cheap as it used to be and I just got awful MPG with that stuff. Used to use it in my Tahoe when I could find it on long trips. Here in FL there's only a handful of stations with it.

What you will find here, is gas blended with as much as 10% ethanol being sold as regular unleaded. It's no cheaper. And is like adding mixer in a drink - better for the house, wink, wink. Worse off, some stations have even been found pushing it with as much ethanol as E85!! There was a rampant rash of that going on here in Orlando a few months ago. All kinds of people with non E85 compatible cars were reporting problems.

I don't have any answers. I'd like to see more sources of oil tapped, new and old. Everybody wants to sink a well and strike it rich. There's lots of oil left in the ground that could be processed. E85 competes with food and that bothers me some - not enough of it comes with post consumer waste. And what of lost technologies? I'd like to see advancements in steam technology, a modern adaptation of the Stanly Steamer. And so on.

Yea, you've got one hell of a commute NODIH. Haven't done that much driving since college - 180 miles a day back then. I know you talked about this some awhile ago. Your best bet is to get a used Honda Civic, Geo, or Aspire for your commute. Keep your Caddy for the weekend.

Checked the tire pressure on my Park Ave, 35 psi, but max on the tire is 44, so I went to 44 front and 40 rear. Hopefully will help get better mpg..... Every little bit helps....

That should help NODIH. Got me 2-3 MPG in my Honda Accord.

Do you draft on your highway commute? That will save you some too - you don't have to be right up on a truckers hoo ha to gain benefit either. 12-15 feet will still garner a gain.

Barring stuff that could be done stock to a FWB to improve fuel economy, if you were an automotive engineer with tons of disposable income and you had to build one of these from the ground up, making it efficient but saving power, what would you do? I'm talking about keeping the body and interior and stuff.

Steam power baby!!!

First, everything would have to go on a diet. At 4500lbs that's a chunk to move around. 2nd, Diesel. When a 3L engine can dish 210 horses, and 400 lb ft (See Benz E class) 23/32 mileage rating in a chunky benz like that, why not for our cars? Heck 18/24 in the 4800lb M Class. I figure a solid 4L Diesel could even make for a pretty fun vehicle. Bonuses, the massive torque could bring a tranny with less gears, and taller cogs, which could be really helpful on the highways. Or, a different drivetrain altogether. Instead of a fuel engine that powers the car plus batters, give a small engine that just feeds some generators and batteries, and then an electric motor that actually moves the car. (See a locomotive.) and I'll post more later.

Sorta what I wanna do, build a car that where the transmission is would be a generator and an electric motor powering the tailshaft. So you have minimal wire length (and copper wires of that size can weigh a lot). Run the car on a 80KW electric motor or so, and minimal batteries and run the engine like a loco, efficient (diesel most likely, turbo, 3L probably can do well).

I wanna make my Park Ave an Hybrid. Add a rear drive axle or front drive spindles in the rear with drive axles and some sort of diff in the middle, and then power it by an electric motor mounted directly on the diff, add a ton of batts, like Optimas or some sort of good deep cycle batteries, gel cells or something in the middle, under the rear seat or in the truck up under the package shelf. Add a ETC throttle control and maybe add that functionality to the factory PCM (it is there, even for a 2000) only have that part controlling the electrics and the regular throttle stay on stock cable operated.

So this makes my car a killer hybrid, fast as heck on take off with both engines engaged, or great city mpg on the electric. Then work out some sort of regen braking to charge the batteries up. Then build in some really good batt chargers that can charge up the battery bank in a few hours. And then add some 140-250 amp alternators up front to do what they can to charge up the batteries too when driving.

The car will be a heavy sled for sure, probably cost more in the engineering exercise than it will gain back, but would be neat to do....

Here is my current cost analysis spreadsheet...

if anyone wants it to play with, shoot me your email, they won't let me put .xls attachments here...

I can say, it puts things into perspective, but it also shows things didn't look at good as I had hoped on mpg on the Buick on E85.... :(

:cookoo::cookoo:>64 "Might cost more in engineering" So if this thing could be made, why are we still stuck with sardine cans with no power as the alternatives? It wouldn't be cost effective to make just one, of course, but what about assembly line type stuff? Imagine a big, gourgeous car like a FWB that has lots of power and is fuel efficient??? :want:

With the profit margins on the 94-96 FW's, they SHOULD have been that efficient!