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ZenArcade 01-19-2010 03:02 AM

New user with a classic car
 
Now, I've trolled this forum for a bit and I'm fully aware of the V8 flames that are coming.

I've got a 1979 Buick LeSabre with a Pontiac 301 (4.9L) V8. This beast weighs in at around 5000 pounds (according to driver's door stickers.) Not sure on the transmission type, but it's either a TH200 or TH350 3 speed automatic.

By this point everybody must be thinking it's a gas guzzler and I should dump it for a much smaller car. Well, on the contrary, this car is actually quite fuel efficient for it's age and type. My best recorded trip was a 116 mile trip with a 25 mpg average. This was at a constant 60 mph for the first 80 miles, and through rush-hour traffic on a Saturday for the next 36 miles.

Since then I've taken half the exhaust off to offset the fuel required for warming it up in the winter. The original owner had the catalytic converter taken off, for whatever reason. So now I'm running with an open exhaust after the headers, with no muffler. The car is surprisingly quiet despite not having a muffler, and is still just as clean burning as it was before. (Due to the cat already being removed)

Around town I'm averaging from 17-20 mpg, and on the highway I'm getting around 21-23 mpg. Highway traffic now is slow going due to the winter weather, so I'm not getting as much mileage as I should.

In the near future I'm going to be reassembling the exhaust, this time with full 2.5" piping, a cat, and a magnaflow straight-through muffler. This will be a huge improvement over the stock system which trimmed down from 2.5" piping at the headers, to 1.75" at the tailpipe. I'm also keeping the stock design, which has the piping wrap around the rear axle, in the interest of preserving torque over a straight-piped design.

As far as emissions, which I am still concerned about (HC's and NOx's. CO2 as the main drive for global warming has been proven to be a crackpot theory by the global science community), this V8 was the only GM-made V8 that conformed to ALL emission standards for 1977-1981. It went a bit under the standards, in fact. But due to GM corporate mandates, Pontiac was forced to stop making V8's.

I'll also look into my gearing in the future and let you guys know. My torque peak is at 2000 rpm, and that's usually where I'm at when cruising 55-60 mph. I've got 265/70/15 radial tires all around.

So, let the V8 flames ensue. But I'm proud of this little small block, and I'm sure this will provide hope for the rest of us with classic cars that are still concerned about fuel savings. :)

Laurentiu 01-19-2010 04:42 AM

Welcome...What matters is that you are concerned with your fuel consumption and your efforts to improve that . Someone can drive a 4 cyl. 1.6 liter and have a greater consumption if they drive inappropriately..

Hope you enjoy the forums and hope you improve your MPG...:turtle:

P.S. I also love high torque in cars, that's why I plan to acquire a Diesel-engine car in the future...


http://i48.tinypic.com/20qnr0o.jpg

tim3058 01-19-2010 08:51 AM

Welcome to the site ZenArcade, and congrats on the "lead sled". I'm slowly working on a few old cars myself ('74 Corvette and a couple 79 Camaros), I'm with you on trying to up their mpg. Cheaper it is to drive em the farther we can cruise em.
Always liked the look of the real big cars like yours. And getting 25mpg @ 80mph in a 5000lb land yacht is pretty impressive. I bet it rides nice too.

Ryland 01-19-2010 11:58 AM

If you read up on exhaust design you will quickly learn that bigger is not always better, exhaust fallows the same rules as a musical instrument does because it's a pulsating flow, It's about the math not the "restriction" unless of course you don't believe in math.
With a vehicle of your size and I imagine you would like to keep the look of the vehicle as much as possible, then I would start with synthetic fluids all around, an aluminum belly pan is going to help smooth air flow on the rough underside is going to help alot at highway speeds, also going with the next step narrower in tire sizes at max side wall pressure is another proven way to help.

Frank Lee 01-19-2010 03:54 PM

Quote:

also going with the next step narrower in tire sizes at max side wall pressure is another proven way to help.
It is?

gone-ot 01-19-2010 04:04 PM

...with "headers" there are two movements going on: (a) an acoustic 'wavefront' that moves through the gas at about 1700 fps (speed of sound in hot air) and (b) the mass movement of the gas slug itself as it moves down the pipe at about 300 fps.

...pipe diameter affects speed of mass movement down the pipes, while piple length affects acoustic "reflection" (Helmholtz tuning) time and strength (camshaft valve timing comes into play here too).

...too large diameter pipe and the mass movement slows down below the optimum value of about 300 fps; too small diameter pipe and the mass movement increases above the optimum value and 'back pressure' builds. 300 fps seems to produce the best "scavanging" action between the exhaust gas flow and the cylinders.

Clev 01-19-2010 04:15 PM

That's excellent mileage from such a beast. You might benefit also from a newer 4-speed with lockup torque converter (especially if you do a lot of freeway driving.)

BTW, I don't want to start a flamewar, but the global science community is not known to pursue "crackpot theories."

gasstingy 01-20-2010 08:54 AM

Welcome to the forum. I wouldn't dare attack a vehicle because it's a V-8. My daughter has a '99 Trans-Am with a 350 / 6-speed. We drove it to the National Corvette Museum in November and challenged each other to maximize fuel economy. I drove up and we got 29.8 mpg @ ~60 / 65 mph. She drove back and got 29.4 @ about the same speeds. How did I beat her in her car? When we came back, she had heavy traffic in Nashville and before we got to the Alabama line, she had to turn on the (popup) headlights. Either way, a properly driven V-8 in the right vehicle can get reasonable economy. There are some great tips here. Enjoy the ride :)

rgathright 01-20-2010 09:01 AM

Welcome to the forums!

If you only you had a 700R4 tranny!

Clev 01-20-2010 10:18 AM

Quote:

Originally Posted by gasstingy (Post 155477)
Welcome to the forum. I wouldn't dare attack a vehicle because it's a V-8. My daughter has a '99 Trans-Am with a 350 / 6-speed. We drove it to the National Corvette Museum in November and challenged each other to maximize fuel economy. I drove up and we got 29.8 mpg @ ~60 / 65 mph. She drove back and got 29.4 @ about the same speeds. How did I beat her in her car? When we came back, she had heavy traffic in Nashville and before we got to the Alabama line, she had to turn on the (popup) headlights. Either way, a properly driven V-8 in the right vehicle can get reasonable economy. There are some great tips here. Enjoy the ride :)

Back in the mid-90's, Car and Driver claimed an average 26 mpg while driving 100 mph across Montana in a Z-28.

rgathright 01-20-2010 10:26 AM

Quote:

Originally Posted by Clev (Post 155492)
Back in the mid-90's, Car and Driver claimed an average 26 mpg while driving 100 mph across Montana in a Z-28.

Those engines had high amounts of low-end torque and a good tranny gear ratios. Just shift gears and never hit the gas pedal! :turtle:

Laurentiu 01-20-2010 10:40 AM

The higher the torque the higher the speeds at which you can "cruise" for FE...Diesel's rule in that :D

MadisonMPG 01-20-2010 11:57 AM

No one hates V8 here, we hate people who drive inefficiently.

bgd73 01-20-2010 04:18 PM

301 pontiac. I ran one in a delta 88. Very reliable, EGR was a monster, engine needed very deep cleaning, and even removed nuclear debris (Quite a phenomona if to live through it) EGR has been a perfect omen...even in a little subaru...

when back to as normal as I could get it (I was 16 back then)
new lines, etc, 15mpg was good.

the highway had an unusal realm..does your transmission indicator have an "S" somewhere inbetween D and 2 and 1?

that was amazing, kinda like an older powerglide(?) 2 speed with a looooong drawn out gear.

treat it like the gearing of a diesel, big tread etc (I don't mean donk)

I wondered what staying in the rochester little two barrel side of things correctly would have done for my own 301. good luck...

a 600 holley even barreled would be a very very mathed fit.

ZenArcade 01-27-2010 01:51 PM

I managed to find out that I have 2.29 gears in the back, so that puts me at around 1600 rpm at 60 mph. Not bad at all. I'm almost positive I've got a TH200 3 speed on it, and I'll check the oil pan for confirmation next time I drive it.

I've also ran several different dyno's and simulations on it, and I found that a mild cam with a little bit of overlap would increase my highway mpg by 2-5. While you can't exactly trust the numbers 100%, it does tie in with logic. The stock cam has almost no overlap, if I remember correctly. So some overlap will do her good in all realms of efficiency. Not to mention that I very rarely run at WOT, so my EGR might as well not exist.

Oh and I'm also going to lean up the mixture a little bit. Smells a little too rich right now.

And a tranny swap is almost 100% out of the question right now. I don't even come close to having the money right now. One day I'll throw in a 4 speed though

Domman56 02-06-2010 01:48 PM

Haha i understand where you're coming from I've got a camino with a 5.0 V8 and that gets pretty good mileage too These old V8's are actually pretty efficient if you drive em right

Frank Lee 02-06-2010 04:38 PM

No, they aren't.

In this day we should not be satisfied with anything less than 30 mpg.

Clev 02-06-2010 05:04 PM

Quote:

Originally Posted by Frank Lee (Post 159542)
No, they aren't.

In this day we should not be satisfied with anything less than 30 mpg.

From any vehicle. There are six 2010 SUVs rated 30+ mpg, and there's no reason why all current passenger vehicles can't hit that.

Clev 02-06-2010 05:11 PM

Quote:

Originally Posted by Clev (Post 159552)
From any vehicle. There are six 2010 SUVs rated 30+ mpg, and there's no reason why all current passenger vehicles can't hit that.

Let me clarify. That's just large SUV's. There are obviously many smaller utes and crossovers that qualify as well.

30 MPG SUVs | New SUVs with 30 Miles per Gallon

ex-x-fire 02-06-2010 09:27 PM

Get a TH2004R tranny, w/ the BOP pattern. TH700r4 is either SBC or 2.8L patterns. Dump the 301, if you ever take the intake off you'll know why. This is a castration of the pontiac V-8s. Short stroke, no compression ratio worth mentioning, & siamised ports in the heads, if ever GM made a boat anchor this is it. Get a real pont 350, all accessories should swap over, the longer stroke makes much more torque to handle taller gearing. Anotherthing to watch out for on any pont. v8 is very weak timing chain & gears.

Domman56 02-17-2010 12:12 PM

Quote:

Originally Posted by Frank Lee (Post 159542)
No, they aren't.

In this day we should not be satisfied with anything less than 30 mpg.

:confused: I'm just confused by that statement because BOTH of ur Vehicles in ur tag get waay under 30 MPG , Well not the tempo but that still is quite a bit under 30 and that's a 4 cylinder

Clev 02-17-2010 01:02 PM

Quote:

Originally Posted by Domman56 (Post 161527)
:confused: I'm just confused by that statement because BOTH of ur Vehicles in ur tag get waay under 30 MPG , Well not the tempo but that still is quite a bit under 30 and that's a 4 cylinder

Maybe that should be rephrased then. In the modern era of lightweight high-strength steel, direct injection, small displacement turbocharged engines, manumatics and CVTs, lockup torque converters and overdrive gearing, we should not be satisfied with less than 30 mpg from any NEW vehicle.

Nonhog 02-17-2010 01:20 PM

Nice work on the great job of getting great MPG no matter what some say.
I'd be concerned about an O/D trans with a low torque engine like a 301 in a heavy car with 2.29 gears not saying it won't work but think it through.

Remember if you adj. the exhaust(better flow) it will probably require carb work to maximize benefit.

Sounds like fun, pics?

Frank Lee 02-17-2010 02:41 PM

Quote:

Originally Posted by Domman56 (Post 161527)
:confused: I'm just confused by that statement because BOTH of ur Vehicles in ur tag get waay under 30 MPG , Well not the tempo but that still is quite a bit under 30 and that's a 4 cylinder

If I say I'm not satisfied, does that clear up the confusion? :p

The Tempo should get mid 30's but it has an awful a/t. A 5-sp conversion is in order. As you may note if you look at "Blue's" fuel log, it doesn't get driven much. Hardly ever, actually.

The truck is a truck and it doesn't get driven around empty much. It isn't going to get 30 no matter what some people believe, especially when it's working hard.

The ShWing is a disappointment fe wise, but 32 is in line with what I've read they all get. EFI would help a lot on that machine I'm sure. Gearing and aero too.

comptiger5000 02-17-2010 07:04 PM

The older V8s can be great highway runners. They suck the gas bigtime around town, but many of them were geared well to hit their efficiency peak at higher speeds on the highway, as they had enough torque to turn low RPMs and still cruise along easily.

The Mopar 360 in my Jeep will turn 1200 rpm doing 40 in OD (4 speed auto, 4th gear) with the TC locked and still have enough power to GAIN speed uphill around town without downshifting. That's the only reason the mileage isn't much worse than the 6 cylinder in actual use. Now, if I had the money to re-gear it so I wasn't turning 2000 rpm at 65 mph, that would help a lot, as it has the torque to do it at lower RPMs.

tim3058 02-17-2010 07:46 PM

Quote:

Originally Posted by Frank Lee (Post 159542)
No, they aren't.

In this day we should not be satisfied with anything less than 30 mpg.

With a car and an engine that size, anything over like 12 is respectable. I'd be dancing in the streets if my old cars got 20mpg. For the stone-age technology the old V8's had, the fact they could get mid teens hooked to a 3 speed in a 4000lb land barge puts new technology to shame. Nothing like being able to light 'em up when you want to either :thumbup:... I'd guess most of the guys aren't driving em for commuters anyways :D

Frank Lee 02-17-2010 11:31 PM

My '59 Bel Air gets 20. I had a V8 Nova that got low 20s. 20 mpg is not efficient for cars that aren't towing giant trailers or anything. 20 mpg sucks. Now, when the truck gets 20 with a trailer and/or a load, then I dance in the streets.

tim3058 02-18-2010 08:10 AM

Quote:

Originally Posted by Frank Lee (Post 161656)
My '59 Bel Air gets 20. I had a V8 Nova that got low 20s. 20 mpg is not efficient for cars that aren't towing giant trailers or anything. 20 mpg sucks. Now, when the truck gets 20 with a trailer and/or a load, then I dance in the streets.

I wish. The one time I checked my 84 Camaro got 16mpg (wheezer 305), and I'm not expecting anything over 10-14 in the Corvette when it's done.

wdb 02-18-2010 10:46 AM

Quote:

Originally Posted by Frank Lee (Post 161656)
My '59 Bel Air gets 20. I had a V8 Nova that got low 20s. 20 mpg is not efficient for cars that aren't towing giant trailers or anything. 20 mpg sucks. Now, when the truck gets 20 with a trailer and/or a load, then I dance in the streets.

My dad had an '86 Mustang GT with the 5.0L V8, Goodyear Gatorbacks, and a horrendous 3-speed automatic whose only redeeming quality was a tall top gear. He was thrilled to get 20MPG. I loved getting it sideways in the rain and never much cared what the MPGs were. Those were the days.

lumberjack_jeff 02-22-2010 01:39 PM

Welcome!


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