Hate to tell you such is not the case as some will again depend on calibration you are trying to make an argument based on the ONE example you played with...

 

That indeed may be true. It was a EGR calibrated for a early 80's 351w.

 

Great thread guys! Matt, you won't forget the thermostatic air cleaner? Actually made a big difference on my 86 six banger.

Also would the variable air bleed in the Motorcraft cabs count as an emissions device? Prevents fuel from entering idle circuit when decelerating....

Now that I think about it, electric choke and throttle kicker solenoids are also emissions devices too, right?

 

Maybe it's the calibrations of the Fords I have grown up with, but I have always been able to attach a hand-operated vacuum pump to the valve and have it operate on demand, I had never even heard of such a concept (backpressure being involved) until I heard it from you guys.

 

The thermostatic air cleaners are not emission devices and are in place to place to mitigate carb icing and were used before emissions were even a consideration. In certain situations, they may actually negatively impact tailpipe emissions.


The Variable high-speed air bleeds are more for better control of fuel-air mix for fuel mileage considerations. They were not overly common in the states but were pretty much the default carb in Canada with the lower emissions requirements they could put a higher priority on fuel economy. This is most noticeable in the early and mid-eighties if you compare fuel economy ratings for similarly equipped vehicles between the U.S Canada Canadain spec vehicles generally have better fuel economy ratings..
One of the biggest differences between the countries were in allowable NOx emissions. With Canada being much much higher. This allowed for leaner burning fuel-air mixes and more efficient higher combustion temps.

Some Canadian spec vehicles such as the first EFI 3.0L Vulcans used in the Taurus and Sable had no smog pumps and no EGR valves in Canada. The EGR port had had a block off plate right from the factory.
And they got significantly better fuel economy in Canada than they did in the states.. In the U.S they averaged 28-30 MPG U.S real world HWY and in Canada, up to and even over 40 MPG U.S real world HWY was not out of the question. We owned an 86 sable with the 3.0L Vulcan (still to this day one of my favourite vehicles I have owned, and I hate FWD) and achieving 40 MPG plus on the highway was not hard to do even at 70-80 MPH. Our Sabel was quite happy to cruise against the speed limiter of 200KPH and still achieve above 30MPG U.S. (the Sable was more slippery than the Taurus) But this was in the era when FMCoC had quite a bit of autonomy from U.S operations. In 92 U.S and Canadian cars were lock-stepped and Canadain cars and U.S cars were identical in terms of emissions and power trains. The 80's were some of the best years for Canadian spec vehicles especially some of the early EFI stuff that had NO emission devices other than cats, not only did this transfer into better fuel economy but also more HP. Fuel economy increases were reflected in the Canadian specs but the HP increases (some times as much as 15%) were not.

The choke is not really an emission device nor are the kickers and both are primarily for operational considerations but could be calibrated to help reduce startup emissions.

 

This would be a good place to ask, why did Detroit choose the strategies they did, to reduce emissions, early on in the early 1970s? My limited understanding is that nitrous oxides were the main consideration.

So (among other things) they reduced cylinder compression considerably, altered camshaft lobe duration, and retarded ignition timing. Engines ran very hot as I recall. This was at a time of oil price shocks, dollar devaluations, even oil embargos. It looks to me like a whole lot of fuel went straight out the tailpipe, and then burned in the catalyst. Wasn't there any other way to reduce NOX emissions without crippling fuel economy?

 

Ya there were literally hundreds of EGR valve calibrations. The back pressure EGR valves have 2 orifices the intake air is metered as is the vacuum. By adjusting each you can adjust how much force engine vacuum can apply to the diaphragm. Reduce the size of the intake air orifice and engine vacuum can pull more air than the inlet can supply and the valve will open. it is not just about vacuum to actuate the EGR but also vacuum flow. In some ways, the air bleed EGR is better as you can tune them for more or less EGR flow, if you mod an engine you can tune EGR flow by adjusting the vacuum orifice. In sealed units, you have no options other than adding VDV's or a vacuum bleed. But to properly adjust this stuff you need proper 5 gas exhaust analyser. And ones that will do the ranges needed for auto exhaust are still a couple of thousand bucks even for cheap ones. And then you need to be able to interpret the information to calculate A/F ratio.

The EGR is the one emissions device that will impact fuel economy power and efficiency more than anything else. The thermactor systems impacts on power are negligible at best. PCV is zero. Cats only impact if they are a point of restriction. But the EGR has the biggest impact and will yield the biggest gains when removed. Provided the engine retuned for it's removal.

We did not see big losses in HP or Fuel efficiency till the EGR came on the scene then things took a ****. The mid-late '70s were horrific I mean the first 3.0L Vulcan V6 was making as much or even more HP than the 6.6L 400 was in 75.

 

Ding Ding Ding we have a winner.

Engines did run hotter as they upped the cooling system pressures and they moved to the 192°F stats. Back in the '50s, they were using 160° stats for the most part. This is not all bad as the higher the temp you can run an engine at the less it wears.
The Ideal coolant temp for gasoline engines for maximum efficiency is around 240°F but that is outside the realms of economic feasibility in terms of materials and lubricants, even today.

And yes a crap load of unburnt fuel when out the exhaust to be burned in the catalyst, this will make more sense as to why when we cover Catalytic Converters.

 

So are you saying the EGR is the primary cause of lost performance between 60's engines and 70s/80s?

I thought the low compression, heads, and timing/ camshaft profiles were the number one cause of malaise era.

Like you could take a 1978 302/351w and remove the EGR, advance the timing, and slap a 4 bbl on there and it still wouldn't perform like a stock 1969 engine.

To stir the pot, EGR was mandated in 73? wasn't that around the same time as the great gross to net HP changeover? --maybe that's part of the reason HP figures took a dump.

 

That was before before the advent of ethylene glycol based coolant or antifreeze, is my understanding.

The alcohol based antifreeze in common use would boil off otherwise. '64 shop manual for example shows "all engines" t-stat opening at 185°-192° F and fully open 210°-212° so generally higher engine temperatures were apparently in use well before any federal smog regulations.

What I was thinking of was the generally retarded ignition timing, particularly at idle or just off idle. This reduces peak cylinder combustion temperatures by quite a lot, iirc (Because fuel is now burning in the tailpipe, instead of the engine where it belongs) a big driver of NOX. When I started tuning carburetors with a wideband the charts or graphs I found were pretty clear, HC and CO are minimized when ignition timing and air fuel ratios are optomized. This is where best performance and economy are realized.

But, at this point the tradeoff is that NOX emissions are at their highest. So it looks to me at the risk of over simplifying, they just crippled the engines! Am I wrong on this?

One concession to the new reality was to automatically revert to a proper ignition timing curve in the case of engine overheating, by which time it was oftentimes too late for the engine. Excessive engine temperature for example takes the temper out of piston rings, the engine will never again run right.

I guess my question better stated hopefully, if NOX emissiions were the great bugaboo or driver in all of this, was crippling both performance and economy the only practical way to go about this? See where I'm going with that? It looks really, really stupid in hindsight.

 

Two possible explanations;

1. Hindsight is always 20/20. Maybe they tried their best given the primitive tech of the time.

2. (More cynical) I've heard around the net (so take this with two grains of salt) Automakers resisted government regulations tooth and nail, so when they finally were forced to reduce emissions, they said fine. We'll do it, but you're not gonna like it!

This was also the time of 5-mph bumpers and rollover standards, seat-belt interlocks. Automakers were fed up.

I tend to lean toward the first example. However, IIRCHonda or toyota built an engine/prototype in the late seventies that surpassed all emissions standards while having no Cat,air pump et,,, and plenty of power.

 

In the days of Gross HP ratings, the engines were tested with no accessories exhausts or air cleaners.
Net readings had the air cleaners, exhaust and accessories installed, this impacted HP ratings by up to 70hp or more on some of the big blocks. Net ratings were applied for 1972, in 71 GM and ChryCo began advertising both gross and net in 1971 Ford never did this so there was a less direct comparison between net and gross
..

When EGR was implemented is when things really went for a dump it was not solely because of the EGR but the effort to reduce NOx emissions. , It was at that time when emissions strategies affected compression ratios and cam timing, the EGR took engines that had their efficiencies reduced and reduced them even further. Compared to other emissions devices (not strategies), it has the single biggest negative impact on efficiency and HP.

 

I see a lot of talk on the 87+ side for emmisions deletes. I have a 86 4.9l. I hope this thread will go into how to properly delete the egr/smog pump Medusa and cats without causing engine issues.

 

I did because my 86 was missing the pump and cats. state inspector made me put that cat back on, but thats another story.

Easy Just plug check valve port in carb spacer with a similarly sized steel pipe plug. Plug vac lines going to air diverter valve--computer won't care.

Then chop cats off with a sawzall and replace with regular exhaust pipe.

I see no benefit in removing EGR from this engine unless it is malfunctioning. I think you could just remove vac line from egr and plug it, if this is not a backpressure type valve. Otherwise cut a piece of soda can to fit between the egr valve and spacer.

Since the 86 is is computerized, everything else must remain connected or it will run like crap. Odds are you just need to rebuild your carb and fix any vacuum leaks and she'll run great. No need to re-invent the wheel.

 

Future proofing and possibly setting up for other changes. I've been buying parts to get mine back to factory and it is very evident vacuum and emissions parts that these trucks were designed to use are going the way of the dodo. Heck to get a new bimet valve I had to find new old stock, couldn't find a VRDV.

I have to replace the manifolds as it is and if keeping the 300 six in my truck I may want to get a different set of headers and maybe an Offy -C intake which would open up other carb options or a stand alone efi system. In doing something like that you avoid discontinued oem parts, but open a whole new can of worms as you are pretty much stripping the computer from the vehicle.

I believe the thread where the gentleman is tracking how to maximize mogs on his 300 six he is running both an egr delete and 2bbl carb, but had to mess with timing and the such.