How to build a muscle car for better fuel economy?

[BLSTIC]

Or the Ford Kent motor. I mean it was developed in '59 for the Anglia and kept on keeping on until 2002.

I once had ideas about updating the Holden 202 Black EFI. It was an engine designed in the 40's and kept getting updated until the 80's, where Holden engineers tried to make a silk purse out of a sow's ear by fitting EFI. It made 101kw from a 3.3 litre OHV non-crossflow emissions engine in 1984. Except it did it with mechanical/vacuum distributor, single hole injectors (that didn't even have a real spray pattern, they were more or less jets), simultaneous injection, and a non-mapped computer (it was based on an airflow meter signal with corrections for air temp, water temp, full throttle and zero throttle. It was kinda correct most of the time. Basically like a carby without atomisation and fuel distribution problems).

But I have a better sewing machine than 80's GM, I envisaged dynamically matched late model fuel injectors (12-hole items off, say, a Yaris), a modern sequential efi computer, proper TPS, larger plenum, 5-angle valve job, and some minor porting (more about equal airflow than anything else). I reckon it could gain 20kw from that and probably drop fuel consumption by 25% in cruise and closer to 30% around town, should appropriate tuning be done.

But you're starting from a 90's machine, I'm not sure gains of that magnitude are available from something that already has sequential EFI (I assume).

Does your car already have sequential EFI? How good are its injectors? Subaru once had air atomising injectors for cold starts that may help your cause.

[Phoenix'97]

Originally Posted by freebeard

Maybe there was more description, but I missed it. I'm starting to wonder what this car looks like. What color is it?

I can understand why you might not want to post a picture because someone could social engineer the license plate or picture background, but DuckDuckGo can find a picture of one like it. Or with just the year and color [and T-top or lack thereof]. One of these ones:

Does it have the screaming chicken?

The car is White and came that way from the factory. When I have the car resto-modded, I am thinking of having her painted Mystic Teal.

No, the car does not have the Screaming Chicken, they didn't come with them on the hoods in the 90's.

She has the T-tops which may not be helpful for aerodynamics but they are great for spring and summer days to give the feeling of a convertible. I have to balance the "fun factor" with the fuel efficiency. Besides, below 55 mph, it shouldn't make a difference, right?



I am also considering swapping the Trans Am bumper covers out with those from the Firebird/Formula to give me the more streamlined looking Firehawk.



She will be a totally different bird, but a Phoenix none-the-less when she is done.

[BLSTIC]

Below 55mph aero is still a big thing if you're trying to maintain speed. I'd go so far as to say as at 35mph around half your energy goes to drag. In the 90's they had the top of the car more-or-less ok for drag, but the underside is typically a big mess (out of sight out of mind). Minor work on the front and rear (undertrays) can make a huge difference to the underside of the car. I'd say you could drop 35mph cruise consumption by 3-5% with a few hours work.

I think that 55mph aero myth probably came about because if you're not doing 55mph you're in stop/start traffic of some kind, where the (relatively) constant braking wastes most of your energy. Drag accounts for little of this kind of driving, but still has some influence (look at the detail on EV's designed for the city, where every bit of energy counts towards range. The opportunity for 10 miles of extra range outweighs the $50 per car extra it costs).

So yeah, if you're in a city, aero doesn't matter as much, but in terms of effort per economy gain, chasing the low hanging aero fruit is still worth doing.

[Phoenix'97]

Originally Posted by BLSTIC

Below 55mph aero is still a big thing if you're trying to maintain speed. I'd go so far as to say as at 35mph around half your energy goes to drag. In the 90's they had the top of the car more-or-less ok for drag, but the underside is typically a big mess (out of sight out of mind). Minor work on the front and rear (undertrays) can make a huge difference to the underside of the car. I'd say you could drop 35mph cruise consumption by 3-5% with a few hours work.

I think that 55mph aero myth probably came about because if you're not doing 55mph you're in stop/start traffic of some kind, where the (relatively) constant braking wastes most of your energy. Drag accounts for little of this kind of driving, but still has some influence (look at the detail on EV's designed for the city, where every bit of energy counts towards range. The opportunity for 10 miles of extra range outweighs the $50 per car extra it costs).

So yeah, if you're in a city, aero doesn't matter as much, but in terms of effort per economy gain, chasing the low hanging aero fruit is still worth doing.

Yeah, I am aware that the underbody of my F-body is horribly dirty for airflow efficiency. I looked into smooth underbody trays but the amount of work required to fabricate something for my car may be cost prohibitive, and not to mention the added burden of requiring easy access for maintenance under the body of the car. I was willing to overlook this but then again such a tray would help to keep salt from attacking those components shielded by the tray.

I just think that it will cost too much. This coming from the guy spending thousands to modify my car into a V8 hybrid plug-in, lol.

[BLSTIC]

I wrote an instructable on how to prototype trays several years ago. Cost me about $5. If I were to build it in ABS I would say it would cost me around $100

How Prototype Undertrays for Your Car: 5 Steps

[slowmover]

Originally Posted by Phoenix'97

I am going to stress the fact that my goal is NOT to recoup the money spent on this car from gas savings! The goal is to improve upon a car designed in the mid-to-late 1980's that went into production during the mid-nineties with new technology and better parts that have since come to the market! A big improvement is ALL L.E.D. lighting in the car!

Currently my car is in an aged out state and I would like to have her refurbished to like new and with an engine and drivetrain tailored to the type of driving I do with the added emphasis of optimizing for fuel economy where possible!

Some of the advice I have been given on this site I will end up incorporating into the car while other ideas are too far out of the realm for my consideration. For all intents and purposes, this build is supposed to produce a street car that is something that you might expect to come out of the GM plant if they were making this car TODAY! So, extreme Aero-mods are out of the question, especially lowering the car for better aerodynamic effect when this will make the car extremely difficult to drive in the winter. An underbody cover may be considered but for the ease of maintenance I may decide to go without one.

Also, my car can seat two passengers in the back, so it is HARDLY a car that is inappropriate for the family, so long as we don't have more than three children.

Ha!


Good luck

.

[freebeard]

I looked into smooth underbody trays but the amount of work required to fabricate something for my car may be cost prohibitive, and not to mention the added burden of requiring easy access for maintenance under the body of the car. I was willing to overlook this but then again such a tray would help to keep salt from attacking those components shielded by the tray.

Polymetal comes in 4x8, 5x10 and 4x12ft sheets. Here is pricing for 4x8 sheets: POLYMETAL PANELS — $48-108 depending on the color and thickness. You'd want to roll the edges under the rocker panels and cut holes for the pumpkin and stuff.

OTOH I think there is a lot to be said for perforated sheet. It would manage flow along it's length but buffer pressures above and below. And shed sand and water.

[triangles]

Originally Posted by Phoenix'97

I appreciate the thought, on top of suggestions for swapping in a diesel motor! However, the goal is to overhaul my V8 LT1 engine and improve it in terms of power production and fuel efficiency, which is a tough act to balance, not spend additional money to swap in something new.

Besides, I enjoy having a moment once in awhile to let loose and floor the gas pedal! Then, the beautiful idle from my LT1 and then hearing the growls and snarls from acceleration and engine braking are what really make the experience rewarding.

I'm also not reading thru the 20+ previous pages so I apologize if anything below has already been suggested.

I had recommended the engine swap as a cheaper easier alternative than monkeying too much with your thirsty V8. From what I know about late 90's engine technology, it's fuel injected and has a computer managing the ignition timing and fuel injection. This is probably both a blessing and a curse. I'm not sure what is available in the aftermarket that allows tweaking of the base engine map. I'm going to assume there isn't much (probably wrong) but the first thing I would do is get some cams that are optimized for fuel economy. Sure you'll take a hit in max HP but like you said you're not racing it. Further you could also see what pistons are available to change the compression ratio to work best with the new cams. Beyond that there' isn't much you can do and even monkeying with the cams and pistons probably won't get you more than 1-2mpgs since the factory ECU will try and compensate for the changes you make.

Taking things to the next step you can "delete" your cars ECU and put in something like a Megasquirt or microsquirt controller. This will give you complete control of the engine map (ignition timing and fuel) and you can really tune it for efficiency. I would guess this might yield +5mpg maybe as much as +10mpg if your factory engine is really inefficiently setup and you drive very efficiently. I'll repeat that is just a guess but it's about the only way I see of making the engine more efficient.

I am doing this with a 2 cyl motorcycle that is optimized for HP and is also carbureted. Since the ignition control is so crude and you can't lean out a carburetor for low load cruising conditions as well as you can with EFI I should see some significant improvements. That's kind of the beauty of having computer engine management. Tweak for max fuel economy at light load and then switch to max power when floored. It's kind of like cheating having the best of both.

I'm sure this one has probably already been thrown out there but you could find a way to "deactivate" 4 cylinders under cruising conditions.

Anyway good luck and don't let the know it alls who think anything but what they suggest is wrong, discourage you. Keep us updated on what you do and how it works out. Some people just don't understand that sometimes we like to do things because we can, not because it makes any sort of economic sense.

[BLSTIC]

It's a blessing because the stuff is technically there to get the best economy. It's a curse because you can only get incremental improvements over what's there (without altering factory goals). It's not like cars were ever programmed to use more fuel for no reason (once they got the programming ability, which I would say was a late 80's thing), so you've got to figure out *why* it's running too rich or too lean there. It's like: Why run 11:1 air-fuel ratios at high load? It costs power, uses fuel, and doesn't add to engine safety... Oh wait I have cats and they overheat after 30 seconds without the low egt made my running rich.

Sequential injection can only get so much when you're not running massive injectors, and injectors have only improved so much since, especially for two-valve heads (four valve heads now have injectors that have two-cones that point at each inlet valve and timing so that at low loads they can put the entire charge through an open valve)

Spark control in the aftermarket basically hasn't changed since the late 80's so you get screwed over with not being able to use the dual-knock sensor with 4-method closed-loop spark control factory cars got around 2005. There's one Australian car which has an increase in high load torque of about 7% by running premium fuel simply because its spark management and knock detection is so damn precise. No such luck for the aftermarket. Program your ignition, have a knock sensor if it pings, no real continuous octane detection and optimisation.

[cRiPpLe_rOoStEr]

Originally Posted by BLSTIC

Or the Ford Kent motor. I mean it was developed in '59 for the Anglia and kept on keeping on until 2002.

At least in Brazil the Kent/Valencia/Endura-E was phased out in mid-'99. BTW a cousin of my dad still owns a Mk.4 Fiesta with the 1.0L Endura-E.

I once had ideas about updating the Holden 202 Black EFI. It was an engine designed in the 40's and kept getting updated until the 80's, where Holden engineers tried to make a silk purse out of a sow's ear by fitting EFI. It made 101kw from a 3.3 litre OHV non-crossflow emissions engine in 1984. Except it did it with mechanical/vacuum distributor, single hole injectors (that didn't even have a real spray pattern, they were more or less jets), simultaneous injection, and a non-mapped computer (it was based on an airflow meter signal with corrections for air temp, water temp, full throttle and zero throttle. It was kinda correct most of the time. Basically like a carby without atomisation and fuel distribution problems).

Ah, the early days of analog EFI...