Hey, so here I am new to the forums, I found the website through a lot of googling around. I have an front desk job in customer service where I help people when they come in. Too bad nobody usually comes in, so I spend a lot of time on the internet reading around. So here I am, looking to do some hypermilling. I have a few questions, though, about my car! Hopefully some of the experts around here could give me some insight.
Here is my car! (well this one isn't, Although that is a sweet green.) It is a 1980 TR8. It is a 3.5L aluminum block V8, 2 seater convertible, with 155 ponies and 1800 Lbs weight.
Aerodynamically.. I don't know much about aerodynamics. I've read into top up/top down, vortices, tapering, underbody panels, tires and grill blocking. So I slightly understand some of the ideas around. My car has a wedge shaped nose, which (I hope) should give it an advantage in the aerodynamics area, the grill, upon first inspection, is four small, spaced rectangular holes where the wedge shaped hood meets the rubber bumper! However under the bumper is a but of a lip which seems to pick up air going under the bumper and put it onto the rad. This lip is the lowest part of the car and constantly sustains damage from over-zealous speedbumps or the edge of an unfinished road. (Avoid ditches). http://www.tr8.com/TR8PAINT/FAB.jpg It can be seen from this photo the under-bumper lip with attached fog-lamps. (I don't have fog lamps. )
Oh I also have that shiney luggage rack.
So, I understand that I've kind of cheated and posted my introduction and a aerodynamics question in one area but it seemed to mesh together so well! Thanks for everything in advance and keep up the good work. This is an OUTSTANDING website.
Haha I love that green car picture. It's actually that colour, spot on, that dark green. The wheels are the one in the bottom, the red one. And the luggage rack is just like that. The back of the car does cut off pretty fast, with the exception of the odd shaped, pointy, rubber bumper, which you can see in the first picture you posted.
Here is said luggage rack. Odd thing. Looks neat though, chrome.
MPG is still in testing phase. Interwebs claim it 22MPG highway 16 City. But I've yet to meter it as i've not been driving much lately. I did take it out yesterday to the flattest road we have where I live. (Which still isn't THAT flat) and did the Drag Coefficient testing where you coast from 70kph down to... 20 or so, and keep time. And the times weren't unreasonable. This was my first test with under inflated tires, and out of alignment wheels. They are getting aligned today and i'll set the tire pressure to 40PSI (max rec. 35?) to see a notable difference. I read a lot about the tire pressure on the forum and it seems to stir up a lot of discussion, but I'm gathering that the biggest difference in the initial crossing the max line and everything after that is more for pennies. What would be recommended? 40? 42? Anyways, i'm going to take a picture of the front so you can see the odd grill.
Ah yes, and it's carbureated. Carburators are nice in the fact that they are easy to work on and understand, but i've been slowly accumlating money for a modern FUEL INJECTION system. I'll have to do my research into that because I want to achieve much better MPG through a system change. Does anybody know much about fuel injection systems and if some are better than others?
Sure it's a V8 (a small one, at that) but I want to make the best of it for economy. Because I love link. <3
I hesitate to recommend exceeding the maximum marked on the tires. While it's not going to make them explode or anything, it could potentially expose you to liability in a collision.
What size are the tires? For a car weighing a mere 1800 pounds I suspect they're pretty wide and tall. As such I imagine that 35psi will be plenty; more may not provide any FE benefit and may result in many of the usual bugaboos proposed for excessive pressure - harsh ride, bouncy/bad handling, and excessive center wear. The nice thing about experimenting with pressure is it's free and reversible, so you can try what you want and if you don't like it then it's no big deal.
...ok, Tirerack says 185/70-13 (tough size to buy!), so maybe 35 won't be the most that works well.
Most people have the same appreciation for carburetors that you do. I do not share it. To me they are silly Rube Goldberg devices that work backwards, and in the past I had much difficulty understanding them, although recent study has led me to a much better understanding. Fuel injection is conceptually more simple to me; measure air, calculate fuel, inject fuel, measure result, adjust to keep appropriate air:fuel ratio.
Anyway, get a vacuum gauge. With a carburetor, a vacuum gauge will be a huge help for tuning your driving. I have been doing pretty well in my 1980 Buick by trying to keep my vacuum just above the point that would activate the power piston.
As you might be able to see from the green car picture, the tires are actually pretty small and not that wide. Not like you'd see on a new JAG with 15". Perhaps the max 35 would be a reasonable idea, better than under-inflated.
I think carbs vs fuel-injection is really a matter of how you grow up. I understand the concept behind fuel-injection but I've never really HAD one before. So i've only ever had Carbs and they just seemed more simple and like less could go wrong. But, I really suppose which it is you're exposed to. I think getting my hands on a fuel injection system would make it a little bit less intimidating. All those computers and extra lines and sensors and things just seem complex. You can just throw a carb on-top of a manifold and plug a gas line into it goes. (Surprisingly enough).
That's a good idea, I will pick up a Vaccuum gauge tonight. What vaccuum do you get while idling? Hg/ins I think it is or something. What kind of engine in your Buick? Same year as my TR8. What kind of mileage are you getting?
Fuel injection doesn't need to be as complicated as it is in some vehicles. Early electronic fuel injection systems were known as Throttle Body Injection. They looked just like a carburetor at first glance. They used the same few sensors as computer controlled carburetors used. Off the top of my head, those sensors include:
Oxygen (O2) sensors: These measure the exhaust to see how well everything was burned. The computer uses that information to make minor adjustments to fuel rate. (For emissions purposes only, there is a second O2 sensor after the catalytic converter to monitor the cat's operation.)
Manifold Air Pressure or Manifold Absolute Pressure (MAP) sensor: This measures air pressure/vacuum in the intake manifold so that the computer knows how much air the cylinders will get. (Modern vehicles use a Mass Air Flow (MAF) sensor near the air filter for a more precise measurement but keep the MAP for other purposes.)
Tachometer: The computer needs to know RPM to calculate air and fuel.
Intake Air Temperature (IAT) sensor: Measuring IAT allows more precise knowledge of actual air usage for better fuel calculation because air density changes with temperature.
Throttle Position Sensor (TPS): Measures throttle position, obviously, to know what the driver is doing.
A very basic system could conceivably run on just RPM and MAP.
You might want to look up what other people have done with your engine. Following instructions for a more complex setup could be much easier than backyard engineering a simpler setup. I was going to put TBI on my Buick but lately I've realized that it might be better to use SFI (a more modern, more complex system) because it's documented and came OEM on a very similar engine.
Most fuel injection systems also integrate electronic spark control, but I don't think it's strictly necessary. Electronic spark control uses a knock sensor to detect spark knock and back off the timing just a little; this allows it to advance the timing as much as possible all the time, great for power and economy.
Yup, vacuum is usually measured in in/Hg in the US, although there are other scales. I use this: http://www.harborfreight.com/fuel-pu...ter-93547.html
Idle vacuum is about 22 for me. I get up to about 25 while engine braking. I try to accelerate and cruise at 11-14.
My Buick's engine is the Buick 4.1 V6. The 4.1 is the common Buick 3.8 (not the later GM corporate 3800) with a wider bore, using the turbo 3.8's stronger components (crankshaft, etc) and a Quadrajet 4 barrel carburetor. The 3.8, in turn, was previously the 225. The 225 design and tooling was sold to Jeep for a while who sold it back to GM. The 225, in turn, was a Buick V8 (I don't remember which) design with two cylinders removed. The later 3800 was developed based on the 3.8 but was a new design.
Anyway, with low compression for emissions sake, two gas crises just before my car was made, ever-increasing fuel economy and emissions standards, etc, my engine was rated 205ft-lb@2000rpm and a mere 125hp@4000rpm. Reportedly my car's curb weight is 3300-3500 pounds but I do need to get on a scale.
1980 was the last year of no computers. In 1981 they went to a computer-controlled carburetor (CCC), using most of the same sensors as early fuel injection systems. Electronic spark control was added to the 3.8 in 1978 or 1979 but the 4.1 didn't have it until the CCC.
Grandpa bought it new and its first 10 years were garaged but then it was outdoors and neglected. I got it in 2005 with 35,000 miles, drove it a little, and then it rotted in my yard because I was too poor to have a toy car.
Last year I made a project out of it. I put in a 5 speed manual transmission with the intent of making it my daily driver (don't want to drive an automatic) and efficient. I was more successful than I expected although I'm still working on my MPG goal.
The car needs plenty of remedial repairs to almost every system, owing to the years of disuse and neglect. I repair what I can when I have the get-up-and-go (and money) to do so.
You can take a look at my gaslog by clicking my MPG on the left of my post for Christine. My 90 day average is 25.67mpg. Lately I've been having a lot of 27.xx mpg tanks and I almost hit 30 on a recent one. Some of it is modifications to the car but most is driving strategies including some heavy hypermiling techniques. My goal is 30mpg year-round and will require continued improvements to the car as well as my driving.