I've got two questions

1. How do our inline sixes compare to economy engines of today? It's something I've always wondered about and would like to know.

2. I guess this applies to all kinds of engines, but what exactly do headers do for the engine? Are they necessary or is it something just fancy looking people like?

compared to today's 6 cylinder engines i think our inlines get pretty good mpg but the modern motors are fuel injected and that does a lot for fuel economy, pretty sure most Fuel injected motors "recycle" unused fuel by redirecting it back to the gas tank whereas carburetors more simply regulate air and gas. Not that carbs necessarily waste fuel their just not as efficient as fuel injected motors. That being said the motors of yesteryear have some what less moving parts and in a way are more reliable, easier to work on and fewer components make up classic inline from the 60's and 70's

Headers are not just for looks, they direct emissions away from the driver through the exhaust pipe to the muffler resulting in a quiet motor and a safer motoring experience.

My first car was a 72 maverick, loved it to death, was young and didnt know what i was doing so it broke down and couldnt fix it so i got rid of it and regret it every time i see or hear of one

Fuel injection doesn't really recycle unused fuel it runs at a much higher pressure so it uses a regulator and returns fuel that didn't get used just right then but its all about the same. Modern fuel injection is more accurate but i wouldn't say it always makes for better gas mileage. In fact a properly tuned carburated vehicle is about the same, its just more constant on fuel injected. My 200ci gets 26mpg highway going about 70mph with the 5 speed.

Its all about how you build it, these motors were very very restricted from the factory so even little things help quite a bit. Thats the biggest difference i'd say is that most of your newer cars get less gains from upgrades because they are already fairly efficient, whereas you can do quite a bit to make ours much efficient in both power and economy. It also helps that our old cars are very light by todays car standards, and weight is the ultimate killer of economy.

8) given similar displacement, our sixes can approach the fuel economy of modern engines of similar size, and even exceed them with the right combination.

as for headers, they reduce back pressure making it easier for exhaust gasses to flow out of the combustion chamber, preventing dilution of the incoming fresh mixture charge. that increases power, and can increase fuel economy at the same time, especially if you tune the engine to work best with the headers.

My 65 Mustang, when I drive it carefully, can reach around 26-27 MPG on the highway. Our old 99 mustang (greywolfs mustang now) could get around 28MPG on the highway with the 3.8L V-6. My Volvos with a 2.3L turbocharged 5 cylinder can get around 29 MPG on the highway if I keep off the gas, but those cars weight in around 3400 lbs versus the mustangs 2700.

The advantage of fuel injection is not cut and dry. A well tuned carb'd engine can reach the same economy standards. However, the carb can not easily adjust to changes in barometric pressure and temperature which impact the density of the intake air. Carbs are generally tuned for a certain operating condition, so others may not perform at max efficiency. A large jetted carb can be great at WOT for efficiency, but will suffer cruising around town and vice versa. And EFI car can adjust for various conditions better than a carb, unless you wanted to rejet your carb every month for the weather conditions (or get a holley with the adjustable jetting block).

I personally think the real driver for EFI has been reliability. At least once a year I'm retuning the carb a little. Every few years I rebuild the carb. And thats on a car I only drive between 5-8k miles per year. Since I've own my 91 explorer (bought in 1995) I have never had to touch the EFI system outside replacing the fuel pump because the output and inlet lines on top rotted out. Sure, it could probably use new injectors, but it still purrs like a kitten, starts up on cold mornings and hot afternoons without a hitch. Same with my volvos. Still have not touched the EFI system, other than replacing one O2 sensor. People these days are less inclined (or able) to tinker on cars. They expect that when they turn the key it should start up with no hassles. No pumping gas pedals, no messing with chokes.

The emissions on a carb'd engine are no better or worse than an EFI car. I had my 65 tested once. Didn't have to be tested, but I had to have the inspection for the state I was in. The guy asked if I wanted it and told him I didn't think I needed it. He said that I didn't, but I was paying for it anyways. So I had him do it. I compared it to the 99 mustang with the 3.8L in it. The emissions were almost the same, even with the Catalytic converter.

But then again, take a carb'd car to a young dealer mechanic and they'll looked confused as hell when they can't hook up a computer and they'll say "oh, I can't trouble shoot without the computer hook up." Been there...done that.

Comparing fuel economy of the engine is not apples to apples. As slade pointed out the old Mustangs weigh less. Ronmaster2 pointed out that he had a 5 speed transmission. The gear ratios of todays cars are much different than 40+ years ago. None of my old cars cruised down the highway at +/-2000 rpm like the new ones do now. They ran 2500 to 3200 rpm. So you have to factor in different gear ratios too. And something not mentioned yet is that the modern 6 cyl engines are capable of generating 3 times the net HP of stock 200 yet can deliver comparable fuel economy during the commute.
Doug

Doug,

That's why I compared my 65 to our old 99 mustang. Relatively the same size engine. Roughly the same BHP. My 200 is around 170 BHP, the 3.8l V-6 in the 99 was 197 BHP if memory serves. Both have 5 speed transmission, with very similar ratios. The 99 had a 3.55:1 rear, my 65 a 3.40:1 rear. The 99 weighed in around 3100lbs IIRC, the 65 around 2700 lbs.

My only point is that an old car, with a carb'd engine, can be brought up to modern fuel economy standards with some updates. Electronic ignitions and OD transmissions have been the real gainers in fuel economy battles over the years. A well tuned carb or EFI is just gravy.

Positively Ralf":q5wbaqro said:

1. How do our inline sixes compare to economy engines of today? It's something I've always wondered about and would like to know.

Click to expand...

I think it's been answered, the main difference is how it's maintained/ran. An electronic computer is easy and mostly reliable, but a mechanical computer you constantly tune, adjust, finaggle with. it's the nature of the beast. I bet if done right a i6 could hit 35 - 40 mpg. maybe downhill but still possible.

Positively Ralf":q5wbaqro said:

2. I guess this applies to all kinds of engines, but what exactly do headers do for the engine? Are they necessary or is it something just fancy looking people like?

Click to expand...

to me, they are:
A) Fancy, you got to admit 6 pipes on one side and 6 wires on the other side kinda make the engine more sexy
B) Performance, I like to read ClassicInlines tech articles often and alway's see some kind of increase in performance with headers... 5-10 HP from just tubes!!! so that's just a bonus.
C) sound, :roll:

I had wanted to mention in my post that i believed that most of the users here who are running higher HP 200s can still get mid to high 20's in mpg if they are tuned right but i didn't have proof to back it up yet. Its pretty much all based on different variables, your point is true that there are more factors then an engine when figuring out economy. I would say the one thing we have over the newer cars is weight is alot less. If you look back at cars from the 80s we were getting high 30s to low 40s out of compacts and sub compacts. Nowadays only hybrids are advertised at that because every car on the road weighs at least 2500lbs and as such they have to gear it lower so the small engine can move it better which kills economy, it all goes full circle.

Just imagine the mileage we could be getting if they stopped putting the damned ethanol in our gas, my old sunbird got 28mpg mixed no matter how i drove it, my one i have now is the same model just fuel injected and originally rated for better mpg and it never gets above 24mpg with todays gas.

I think you have to compare different kinds of fuel injection, if you multiport the new head and use a good throttle body, you will get very even air flow to each cylinder with very good metering of fuel to each cylinder you won't get with a carb or TBI, making it a much more balanced AFR which creates more power and better fuel economy and your engine will run more balanced with the exact same AFR going to each cylinder and in my opinion last longer, its just a much more balanced system. Before I put the blower on, I ran my 200 MPFI with 19LB injectors with a cam not set for N/A and it ran like crazy and so smooth.