What happened to gasoline in the mid 1970s?

[Mattax]

Wouldnt gasoline flash off hydrocarbons through evaporation?

Yes depending on the temperature and pressure some components may or will.
See the distillation curves in this post.
post #100 Too much timing?

I'll edit this based on RRR's post below.
If you mean change from hydrocarbons to something else, no. Its just a vaporized hydrocarbon. Similar to evaporated water is still water, just in a different state.

 

[Dartswinger70]

I have always though that part of what the cat converter does is burns off unburned fuel (hydrocarbons) in the exhaust.
carb cars are more difficult to set and maintain at stoichiometric fuel ratio... fuel injection is better but not perfect so they both have cat converters.

the water coming out of exhaust is one byproduct of the catalyst as well as was mentioned the exhaust doesn't smell at all. It so odorless that you can smell antifreeze
if you have a head gasket leak even a minor one. On the other hand you
could quite possibly tune your carb by the "smell of the exhaust"

 

[Mattax]

Changes in Fuel.
Here's what I can add.
In the 60s the availability of reasonably priced, high quality, high octane automobile gasoline was greatly improving to meet the needs of the high compression more efficient engines auto makers wanted to produce.
See for example Chrysler proudly telling its techs about the high compression engines in this 1967 booklet Combustion In Today's Engines: Master Technicians Service Conference Session 67-11

Regulatory timeline.
This doesn't cover the changes made by the refining and retail suppliers on their own due to other factors (wars in the middle east, profits, market demand, whatever)

timeline is also from the motor-gas-tech-review.pdf refrenced in my previous post.
Alot of info in there! Download and save.

Finally for an interesting sidenote on changing gasoline formulations in the 1970s is the apparent impact on rubber components in the fuel system see
post #57 Power Valve Selection: The Definitive Answer

 

[Mattax]

I have always though that part of what the cat converter does is burns off unburned fuel (hydrocarbons) in the exhaust.
carb cars are more difficult to set and maintain at stoichiometric fuel ratio... fuel injection is better but not perfect so they both have cat converters.

the water coming out of exhaust is one byproduct of the catalyst as well as was mentioned the exhaust doesn't smell at all. It so odorless that you can smell antifreeze
if you have a head gasket leak even a minor one. On the other hand you
could quite possibly tune your carb by the "smell of the exhaust"

In general the converters hate HC. Too much will shorten their life.
I cant recall the details off the top of my head. I do recall the dual air injection systems fed the exhaust manifold while the engine was warming up. This helped continue the reduction of HC into other components before it hit the cats. Once the engine was hot, the air injection was switched to the cat.
This may have begun with the introduction of the three way cats. I think my '85 is 1st or second year for AMC using 3 ways.

 

[RustyRatRod]

Wouldnt gasoline flash off hydrocarbons through evaporation?

No. It has to burn.

 

[RustyRatRod]

In general the converters hate HC. Too much will shorten their life.
I cant recall the details off the top of my head. I do recall the dual air injection systems fed the exhaust manifold while the engine was warming up. This helped continue the reduction of HC into other components before it hit the cats. Once the engine was hot, the air injection was switched to the cat.
This may have begun with the introduction of the three way cats. I think my '85 is 1st or second year for AMC using 3 ways.

Yeah it's a catch 22. I think the whole emissions thing is bullshit, myself. If they let automakers alone and let them design vehicles themselves, instead of all the gubmint intervention and regulation, we'd have the most fuel efficient car on the planet with all the modern technology. Instead, we have to "waste" that technology making the EPA happy.

 

[Mattax]

In the 60s the availability of reasonably priced, high quality, high octane automobile gasoline was greatly improving to meet the needs of the high compression more efficient engines auto makers wanted to produce.

High octane fuels had been available much earlier. If you read books about WW2 aviation and PT/MTB type boats they all required high octane aviation fuels to stay in operation.

 

[Norbert Schmidt]

Another fallacy. There is no such thing as "unburned hydrocarbons". Hydrocarbons are a byproduct of BURNING fuel. Spent, burned fuel. Hydrocarbons cannot be emitted without fuel being burned. So the correct term would be "unburned fuel".

This is where my opinion differs greatly from that of the "exhaust police". I recently commented about this in another thread.

The way "fuel sniffers" have been programmed since the beginning is, they check for hydrocarbon emissions. If hydrocarbon emissions are more than "whatever" amount is allotted for a given car, or year, or "however" they regulate it, the vehicle fails.

I think this premise is incorrect. It's my belief the MORE hydrocarbons emitted, the more EFFICIENT an engine can be. Take hot rodders, for instance. Most hot rodders keep their mills tuned to the Nth degree. That means advanced timing, correct heat range plugs in good condition, perfect tuneup and so on.

I've always thought the sniffer should check for UNBURNED FUEL. In this way, it would be checking for total efficiency. To me, it makes more sense to use more of the available energy in the fuel. The way it is now, it set up so that the least amount of energy used from fuel nets you the "cleanest" results.

So which way is "more clean" ultimately? ........AND is it REALLY a big enough difference to give a damn about?

That is all very different than my understanding. Gasoline is fundamentally a bunch of hydrocarbons. An efficient, clean vehicle would ideally only emit CO2 and H2O, wouldn't it? Any molecules coming out the tailpipe with both H and C in them are hydrocarbons which should have been burned during combustion. If hydrocarbons are coming out of the tailpipe then some energy in the fuel was not extracted during combustion which is wasted power and pollution. Is that not correct?

 

[RustyRatRod]

That is all very different than my understanding. Gasoline is fundamentally a bunch of hydrocarbons. An efficient, clean vehicle would ideally only emit CO2 and H2O, wouldn't it? Any molecules coming out the tailpipe with both H and C in them are hydrocarbons which should have been burned during combustion. If hydrocarbons are coming out of the tailpipe then some energy in the fuel was not extracted during combustion which is wasted power and pollution. Is that not correct?

Do you think new vehicles are zero hydrocarbon emissions? You're sadly mistaken if you do.

Obviously my point went right by you. It's my opinion that testing for hydrocarbons is the wrong way to go about it. Engines should be tested for efficiency. The more work they can do per gallon of gasoline. More efficiency means more work done per gallon of gasoline, ultimately burning less fuel in the long term = less pollution.

 

[mopowers]

That is all very different than my understanding. Gasoline is fundamentally a bunch of hydrocarbons. An efficient, clean vehicle would ideally only emit CO2 and H2O, wouldn't it? Any molecules coming out the tailpipe with both H and C in them are hydrocarbons which should have been burned during combustion. If hydrocarbons are coming out of the tailpipe then some energy in the fuel was not extracted during combustion which is wasted power and pollution. Is that not correct?

Hydrocarbon emissions are simply a product of incomplete combustion. Just like the graph Mattax posted shows, even a gasoline engine running at a perfect stoich ratio produces HC's. The further the engine strays from stoich in either direction though, generally the more HC's are produced (i.e. the engine is less efficient at converting the fuel into mechanical energy/work).

 

[RustyRatRod]

No. It has to burn.

For those who disagree with this, let me put it another way. While "some" hydrocarbons may escape through evaporation, "NO ONE" is measuring or regulating "THAT" so it's irrelevant. Now. Argue with THAT.

 

[mopowers]

For those who disagree with this, let me put it another way. While "some" hydrocarbons may escape through evaporation, "NO ONE" is measuring or regulating "THAT" so it's irrelevant. Now. Argue with THAT.

That is absolutely incorrect. Evaporative gasoline emissions are heavy measured and regulated. Why do think a bad gas cap seal can trigger a check engine light? Why do think gas stations have vapor recovery systems? Why do you think some new portable fuel containers have those stupid levers on them? Hell, why you think they installed the wonky carbon filters and vapor recovery systems on our old cars? As insignificant as it may seem, plenty of environmental regulatory agencies are regulating them.

 

[ch1ll]

I rember buying 104 octane leaded at unocal (union 76) post 1980.

What I don't get is if a high compression engine can produce more HP per gallon why did we go to lower octane gas?

It seems like higher compression and higher octane wound be more efficient and that trans lated to more mpg

at the onset of government emissions controls and milage requirements the auto industry was scrambling to make cars that were compliant. So was the oil industry at making fuels that would power them. Very few boutique fuel refineries as they call them are in the United States even to this day. Huge money expenditures in both industries back in the day. Refiners are reluctant to build new refineries because the EPA keeps changing fuel requirements and certifying ingredients and blending processes. Tera Ethel lead was removed from gasoline cause it is a toxin.

 

[RustyRatRod]

That is absolutely incorrect. Evaporative gasoline emissions are heavy measured and regulated. Why do think a bad gas cap seal can trigger a check engine light? Why do think gas stations have vapor recovery systems? Why do you think some new portable fuel containers have those stupid levers on them? Hell, why you think they installed the wonky carbon filters and vapor recovery systems on our old cars? As insignificant as it may seem, plenty of environmental regulatory agencies are regulating them.

That's not what I am talking about. You're just looking to argue for the sake of an argument and either "don't get" what I am saying or just want a fight. That's not where I am with this.

When I say it's not measured, I mean at the tail pipe. PERIOD. ALL I was discussing was WHAT the engine BURNS.

 

[ch1ll]

Do you think new vehicles are zero hydrocarbon emissions? You're sadly mistaken if you do.

Obviously my point went right by you. It's my opinion that testing for hydrocarbons is the wrong way to go about it. Engines should be tested for efficiency. The more work they can do per gallon of gasoline. More efficiency means more work done per gallon of gasoline, ultimately burning less fuel in the long term = less pollution.

this is exactly correct. Reminds me of a funny story. Back in the 90’s I had a Renault Alliance(Kenosha Cadillac) 1.2 L motor. At the emissions testing station in Wisconsin. Guy puts the wand in the tail pipe. Comes back to my window and gives me a funny look. Walks back to the tail pipe stands there stupid for a few moments, walks back to my window and says “are you sure this thing is running?”
Religiously knocked down 40 mpg, would top out at over 100 mph with 4 adults in it. Wish they still made them, would buy a new one in a heartbeat. Paid $10,000 new for it in 1986.

 

[RustyRatRod]

That is absolutely incorrect. Evaporative gasoline emissions are heavy measured and regulated. Why do think a bad gas cap seal can trigger a check engine light? Why do think gas stations have vapor recovery systems? Why do you think some new portable fuel containers have those stupid levers on them? Hell, why you think they installed the wonky carbon filters and vapor recovery systems on our old cars? As insignificant as it may seem, plenty of environmental regulatory agencies are regulating them.

I need to clarify. You're talking about the VEHICLE level. What the car itself does. I am not. I am talking about what is measured at a vehicle inspection for emissions out of the tail pipe. There is nothing measured or regulated THERE for evaporative emissions. All of "that" relies on the MIL, CEL or "whatever" you want to call the light on the dash.

 

[Mattax]

generally the more HC's are produced (i.e. the engine is less efficient at completely converting the fuel into mechanical energy/work

I'll quibble that when an engine is producing near its maximum torque and power (for any given rpm) the exhaust HCs are high. So in those instances more HC in the exhaust occurs when the engine is more mechanically efficient, even though its chemically less so.

I suppose the explanation is the most power is made when the most oxygen is used for burning.

 

[Mattax]

FWIW This is what Pa checked at the tailpipe. (This is the only vehicle I know I still have the results for.)
This was a rolling sniff test. My previous cars in NJ only had to pass at idle. I think my '67 was exempt or had a very easy requirement, but '68 definately was not.

 

[mopowers]

That's not what I am talking about. You're just looking to argue for the sake of an argument and either "don't get" what I am saying or just want a fight. That's not where I am with this.

When I say it's not measured, I mean at the tail pipe. PERIOD. ALL I was discussing was WHAT the engine BURNS.

I need to clarify. You're talking about the VEHICLE level. What the car itself does. I am not. I am talking about what is measured at a vehicle inspection for emissions out of the tail pipe. There is nothing measured or regulated THERE for evaporative emissions. All of "that" relies on the MIL, CEL or "whatever" you want to call the light on the dash.

No arguing here. Dude asked "Wouldn't gasoline flash off hydrocarbons through evaporation?" It absolutely does. Obviously those HC's aren't emitted through the tailpipe - hence the term "evaporation." Have a good weekend.

 

[mopowers]

I'll quibble that when an engine is producing near its maximum torque and power (for any given rpm) the exhaust HCs are high. So in those instances more HC in the exhaust occurs when the engine is more mechanically efficient, even though its chemically less so.

Yeah, that is interesting. I've always thought that NOx/HC/CO graph is neat. It just shows that there isn't one sweet spot for minimizing all pollutants.

 

[Norbert Schmidt]

Do you think new vehicles are zero hydrocarbon emissions? You're sadly mistaken if you do.

Fortunately, I don't think that so no tears need to be shed.

Obviously my point went right by you. It's my opinion that testing for hydrocarbons is the wrong way to go about it. Engines should be tested for efficiency. The more work they can do per gallon of gasoline. More efficiency means more work done per gallon of gasoline, ultimately burning less fuel in the long term = less pollution.

A car could be quite efficient but still exhaust plenty of pollution. I think it makes sense that if the goal is limiting pollution then test directly for pollution. Don't test for something else assuming it is correlated.

 

[Dartswinger70]

In general the converters hate HC. Too much will shorten their life.
I cant recall the details off the top of my head. I do recall the dual air injection systems fed the exhaust manifold while the engine was warming up. This helped continue the reduction of HC into other components before it hit the cats. Once the engine was hot, the air injection was switched to the cat.
This may have begun with the introduction of the three way cats. I think my '85 is 1st or second year for AMC using 3 ways.

I have an 86 5.0 Fox body Mustang with the air pump system intact. It pumps air to the cat I am thinking to get the cat at the required operating temp ( feed fire air) one of the reasons I bought the car is it was stock. It still gets emissions inspection in Pa which is gas cap check and visual. I think leaving it there helps with that.

 

[LO23M8B]

I rember buying 104 octane leaded at unocal (union 76) post 1980.

What I don't get is if a high compression engine can produce more HP per gallon why did we go to lower octane gas?

It seems like higher compression and higher octane wound be more efficient and that trans lated to more mpg

NOX

 

[RustyRatRod]

No arguing here. Dude asked "Wouldn't gasoline flash off hydrocarbons through evaporation?" It absolutely does. Obviously those HC's aren't emitted through the tailpipe - hence the term "evaporation." Have a good weekend.

I think we're in agreement from what I can see.

 

[LO23M8B]

[QUOTAE="Norbert Schmidt, post: 1973462445, member: 58087"]Hi,

I wasn't around in the mid 1970s. I've been reading old threads here that containing "octane" and reading articles on the web. What I've gathered is the following which may be mostly wrong. I'd love to know what the real story is.

Before the mid 1970s, people used leaded gasoline that had approximately 88 octane. The lead acted as an anti knocking agent and compression ratios could be as high as 10.5 like in a Chrysl


A stock 340 10.5/1 motor never ran on 88 octane. ps Sunoco 260 was were it was at!