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Discussion Starter #1
My economy car that got great gas mileage is gone (totaled). When I return to work, I will be driving a 1970 Nova that is 1400 lbs heaviest and has eight cylinders instead of four (5.7 liters instead of 1.6 liters). The engine already has TPI and is bolted to a 700R4 transmission & 3.42 gears. I came up with lots of aerodynamic tricks and took it from 22 mpg to 26 mpg hwy. My daily commute is fifty miles round trip on country roads (several stops & turns). Pondering changes on the engine to get the most efficient burn and try to squeeze out just a little more fuel economy. Any input would be appreciated. These are my thought on it right now.

1) Add a small fitting & hose from the rear coolant crossover in the rear of the intake to the heater return hose for steam return. It will make for more even temps across the engine. Also a proven method to drop operating temps.

2) Replace the 180 thermostat with a 195 degree stat. (Proven to give better mpg.)

3) Replace the one wire O2 with a heated sensor to maintain closed loop. I could go 3 wire or 4 wire. (My O2 sensor in the a header collector.) GM added heated oxygen sensors to all production cars in '93. Ford added them earlier than that.

4) Reconnect coolant to the throttle body. (Cold air makes more power. Warmer makes for better mpg. That's why you get better mileage during Summer months.)

5) Partial grill blocking to cut a little more wind drag. The grill opening is like a large mouth bass compared to modern cars with the same displacement engines.

All of these ideas are based on what I have seen manufacturers utilize on later model cars (cars built after the TPI engines left production. Think LT1 or LS1.) I do not want to invest in gimmicks like magnets on the fuel line or a 'Tornado' do-dad in the air inlet. Just lost two weeks pay while recouping from the accident so trying to stay someone cost effective.
 

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On my 72 El Camino with an 89 TPI motor 2, 3, and 4 were done, 4 did not make a difference. 1.6 ratio rockers were added to the exhaust which improved power. Also used Mobil 1 oil.
Do not know your target mpg but the El Camino at 4200 pounds with 3.73 gears and 28" tall tires would get 18 - 22 mpg depending on the application of the little pedal.
 

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TpinovaII,

If you're already getting 26 MPG you're doing really well with a heavier Nova. Would you mind sharing what you've done to the engine, heads, cam, computer chip work, etc. Or, if you've already explained that in a thread please give me link to the thread.

I have a disassembled 1991 Camaro L98 5.7L TPI, the stock L98 heads are in need of new valve seats but I don't know if I want to invest the money into them, or into new heads.

If you make your proposed changes please post the results. I'm interested to see if they improve fuel mileage.

Good luck, Ed
 

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Start using gas without alcohol in it.
Look here to find locations near you: http://www.buyrealgas.com/

And as others have said, use synthetic oils and lubes....... and run your tires at 38-44 # of air.
 

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Discussion Starter #5 (Edited)
Thanks for the replies. I have ran nothing but Mobil-1 Synthetic in my Nova since the late 90s. I have located every Ethanol Free pump within a 30 mile radius of me and try to always fill up there. (In fact, one is just three miles away.) Keeping tire pressure at about 38 psi already. (Running 205-55-16 front & 245-50-16 rear.)

My drivetrain is pretty basic. I started with a '94 350 crate engine & '92 Tune Port Injection and GM electronics (speed density). It has a mild Lunati roller hydraulic camshaft. It also has Edelbrock cylinder heads, 52mm throttle body, & intake base. The runners are from Arizona Marine. Cold air comes right through the radiator core support. The 700R4 has a 2150 stall with lock up (stock Corvette part). The aerodynamic upgrades worked surprisingly well. I added a bumper mounted air dam (chin spoiler/whatever), a lower closeout panel, & a rear diffuser. The fact that the car rides pretty low and has a rake to it certainly helps. Honestly the springs have just relaxed that much over time. Me and this car have been together for a long time.

I'll admit my highway mpg is pretty good for this car and this engine. My city mileage is a different story. This thing chugs gasoline in stop & go traffic. Getting better mpg on the hwy would, of course, be awesome. But my commute won't be all highway. I need the city mileage up. The Honda I just lost averaged 35 mpg during the week. It would knock down 42 mpg at 60 mph. Bottom line is, spending more money for gas means less money for groceries. And with a growing family, that's scarey right now.:(
 

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I ran a MAF set up with a true cowl induction air intake. Speed density is not going to work well in city type driving or at low speeds. Easier to make look good though :yes: Sticking MAF sensor in the air stream is just is hard to make pretty:)

 

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Discussion Starter #7
So, today the old girl got a 195 degree thermostat & two 8" x 6" black plastic panels were secured behind the grill (as close to the headlights as possible). Now Air enters through the remaining 24" in the center and the openings in the bumper.

An AC Delco ASF-74 three wire heated oxygen sensor has replaced the old one wire O2 sensor. I made an adapter harness to retain the original one wire plug & tied down the ground lead to the rear of a cylinder head. Tomorrow, I plan to install a relay & 10 amp fuse for the heater lead. (An ignition hot will energize the relay.) I did some research and the Delco sensor is proven to be more accurate than the aftermarket offerings. And all of the oxygen sensor upgrade pieces came from the local Pull-A-Part. (When mama says we ain't spending a lot of money on this at Christmas...:rolleyes:)

Probably going to hold off on reconnecting coolant to the throttle body. 1) I can't find any documented proof or testimonials that it will improve mpg. 2) Too many changes at one time can sometimes be a bad idea.

Hopefully, there will be some good news to report later.
 

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Probably going to hold off on reconnecting coolant to the throttle body. 1) I can't find any documented proof or testimonials that it will improve mpg.

My good friend Rodney, who owns SpareECM told me that I should by all means keep the coolant hooked up to the throttle body. It is designed to stabilize the air intake temperature and improves overall drivability. If it didn't work, GM would have not installed it.
 

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Tires can also improve milage, many econo cars have tires that will get great milage, but lack in performance. It maybe worth it for commuting.
 

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Discussion Starter #10
Wired the power to the heater for the O2 sensor today. Also connected the throttle body back inline with the heater core. Right now it will only heat up when the heater is on, but it's a start. Opted to hold off on the coolant line from the rear of the intake. Pumped 19 gallons in the tank today and wrote down the mileage. I report back to work Friday night and hope these changes will work in my favor.

My good friend Rodney, who owns SpareECM told me that I should by all means keep the coolant hooked up to the throttle body. It is designed to stabilize the air intake temperature and improves overall drivability. If it didn't work, GM would have not installed it.
Thank you. This is exactly the kind of advice I was looking for. The coolant was reconnected to the throttle body today. Between it and the heated O2, the car felt very smooth at slow speeds around town.

Tires can also improve milage, many econo cars have tires that will get great milage, but lack in performance. It maybe worth it for computing.
I am aware of this but am struggling in this area. This car has a lot of Global West & Hellwig upgrades. She is a true corner carver and makes a ton of low end torque. If I put a hard compound tire out back, the car tends to 'drift' on to the highway or into traffic. Obtaining dry traction is difficult unless there is a good tire out back. Cornering requires a good tire in front. Skinny tires get more mpg but at the cost of traction, handling, & looks. I keep telling myself that my tires need to be a compromise but its tough to give up all my fun. I'm already having to force myself to baby the throttle. It's kind of like having your favorite cake in front of you and only taking a small slice. Deep down, you know you want to indulge. :devil:
 

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Just a suggestion regarding tires...if you haven't already, take a look at Tire Rack's rating of tires. I have a set of Michelins, rated at a very low rolling resistance, that do very well in corners, on dry pavement, and on wet pavement. Just a thought.
 

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Electronic speed control can also boost mileage. Mary and I can take the same trip in the same car, I use the cruise, she doesn't and I average 3 mpg more on the 140 mile trip to dads house.
 

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ahhhh!!! nobody around me has good gasI knew I was getting played on fuel.
Found you some here :yes:

Beards 66 - UNBRANDED
6402 E Central, Wichita KS
Ethanol-free octane ratings: 87 91


Here is another source for finding gas: http://pure-gas.org/
 

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I saw where a Prius swapped from stock, low rolling resistance rubber and lost 5 MPG.
I saw where a Prius swapped from stock, low rolling resistance rubber and lost 5 MPG.
You mean for the rubber band power? :eek:

A few years ago I was considering installing a Gear Vendors overdrive on my 1 ton dually pickup. It all sounded wonderful until I sat down and figured out the cost vs fuel savings. Basically it didn't pay for itself until the end of life for the truck so other than the good feeling of installing it, bottom line was there were no savings at all. For the most part, spending money on all the gadgets, special this and that, worrying about every MPG, going too fast or too slow, just isn't worth the personal stress or $. I have a neighbor that the first thing he tells me about his vacation is he got 21.367 MPG. His highest priority in taking any trip is how many MPG he can coax out of his car. I ask "did you have a good time"...he says "oh, yeah, it was Ok but I had a headwind coming home that really cut my mileage down".

As an example, increasing your mileage 2 miles per gallon is not real easy to do if everything is running correct. Two MPH increase is roughly 45 gallons a year difference. You can't buy a lot of parts that are going to make a significant difference in mileage for the cost of that fuel in most cases.

Insure the A/F tune is good, tires are inflated to recommended pressures, and drive the speed limits, and don't worry about it...it will need gas when it says "E".
 

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Discussion Starter #18
Thought I should add an update about my mpg progress. My Nova has been averaging 17 mpg combined city/hwy. (I don't have any new highway numbers yet.) These numbers would probably be better if I could get through an entire tank of gas without hossing on it. I don't know why this is but at least one day out of the week there will be somebody driving 35 in 55 mph zone. About six or eight miles is all I can take of that. (I refuse to be late for work because of them.) And if that 'go pedal' hits the floor, you can see the gas hand dropping. :rolleyes:
 

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Thought I should add an update about my mpg progress. My Nova has been averaging 17 mpg combined city/hwy. (I don't have any new highway numbers yet.) These numbers would probably be better if I could get through an entire tank of gas without hossing on it. I don't know why this is but at least one day out of the week there will be somebody driving 35 in 55 mph zone. About six or eight miles is all I can take of that. (I refuse to be late for work because of them.) And if that 'go pedal' hits the floor, you can see the gas hand dropping. :rolleyes:
LOL, I hate that with my commute too, it about 45 miles or so one way. I try to set them up to pass with the least amount of throttle and roll pass, not fly by. It gets easier with time too. Another way to pick up a mile or 2, is to put in neutral going down hill and let it free roll. My CTS being standard is easier to do it with, but I can pick up a bit with it too.

Keep the updates coming!
 

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Buy another $1k early 90's Honda CRX and get 45 mpg, and not worry about your classic car getting smashed in daily commuting?

I drove mine daily for almost a decade, but I've come to enjoy NOT doing that.

Kev
 
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