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[L31MaxExpress]

But exhaust gas isn't consistent across a mile (or any other distance), so how does knowing the total output help? What matters is the concentration of what's put out right?

That is where I disagree with that thinking. Grams per mile can be generated with somethibg like an IM240 test where various loads are encountered.

 

[L31MaxExpress]

I know we have gotten way off topic though. Technology has marched on, well beyond pushrod engines. His stock 4.3 has maybe 20 ft/lbs to offer in an economical rpm range without making massive changes.

 

[618 Syndicate]

That is where I disagree with that thinking. Grams per mile can be generated with somethibg like an IM240 test where various loads are encountered.

Sure, but I still don't see how total output is a better method of determining concentration of contaminants.

 

[L31MaxExpress]

Sure, but I still don't see how total output is a better method of determining concentration of contaminants.

Because a lower total is less output period. Concentration of the output does not change to total output. The old air pumps diluted the exhaust but did little more than skew the numbers.

 

[618 Syndicate]

Concentration of the output does not change to total output.

Agreed, but we're trying to measure air quality I.e. the amount of contaminants in the air, so the concentration is more relevant than the amount.
I get what you're saying, I just don't think it tells us what we need to know.

 

[Erik the Awful]

So if what you're saying is accurate, why haven't manufacturers done this themselves? What's the trade off?

My opinion is that when our trucks were produced, GM's accountants had done a lot to demotivate their engineers. If what was on the truck sold, there was no bonus in improving it. Gas was under a dollar a gallon and mileage wasn't a winning sales pitch. They get worse mileage when you open the exhaust up because they aren't tuned for it. I also remember looking under a 1995 Infiniti Q45 and seeing headers and an H-pipe from the factory and wondering what the crackheads in RenCen were thinking. That's a lot of why I was a Nissan tech instead of GM.

 

[618 Syndicate]

My opinion is that when our trucks were produced, GM's accountants had done a lot to demotivate their engineers. If what was on the truck sold, there was no bonus in improving it. Gas was under a dollar a gallon and mileage wasn't a winning sales pitch. They get worse mileage when you open the exhaust up because they aren't tuned for it. I also remember looking under a 1995 Infiniti Q45 and seeing headers and an H-pipe from the factory and wondering what the crackheads in RenCen were thinking. That's a lot of why I was a Nissan tech instead of GM.

I get that, I was more thinking about modern vehicles. He's saying that he can have the best of both worlds, performance and economy, I was asking if that's the case, and it's simply a matter of cam phasing or whatever, why hadn't manufacturers done exactly as he had.

 

[Erik the Awful]

The 2023 Corvette gets 27 mpg on the highway, so I'd say they do. But fuel economy still isn't a big seller. I remember fifteen years ago when my wife and I were looking for a 1995-2000 era car to replace her Chevy Lumina and every V6 we looked at only got 18 mpg, which was DOWN from the early and mid '90s. We finally found a Honda Accord V6 that got 20 mpg. Just a few years later gas prices spiked and suddenly every V6 was up in the 20-24 mpg club. Now they're back down again.
Look at other countries where the average fuel mileage is at least half again better than ours. Crank that gas tax up and you'll suddenly see double-digit fuel economy increases.

 

[0xDEADBEEF]

I got 28 mpg coming back from Bowling Green, haven't been near that since. The car does basically have headers from the factory, but it's the DOD that really bumps the MPG up. It'll jump up about 5 mpg once it kicks in. When I run with it disabled I don't see above 20 mpg.

Vehicles got heavier due to safety standards is one reason for declining economy.

 

[stutaeng]

So basically OP needs to get rid of the big, heavy and non-aerodynamic box truck with an archaic pushrod engine and get a civic or similar? Or did I miss something?

OP: What is your MPG anyway? I'm trying to think of a modern vehicle for your needs that may give good fuel economy...I can't think of any.

I think a Ford Transit with the latest-tech. V6 gives mid teens MPG per the manufacturer. Around 14 city? I bet the real world is lower. Highway is a bit better it seems. I think that has to do with the fact they are unibody, and therefore, lighter than a frame-on-body equivalent. We know several families that have the Transits. One Dad told me they suck gas like crazy, but I didn't ask what the actual MPG was, or if he even knew.

My experience with the 8 lug Express vans is somewhere around 12 MPG, even the later ones. I drove a 2500 with a SBC 5.7 out of high school making window blind deliveries and drove it like I stole it (dumb me!) I recall 10-12 numbers. My neighbor is a paint contractor and his van has the 4.3/6 lug. I don't know what he gets, but probably the similar. We rented a 15 passenger once and drove to Georgia and I recall around the same MPG per the cluster reading, and loaded with people to the max.

Maybe the smaller turbo diesel engine equivalent full sized vans get much better MPG?

BTW, I don't think them Ford engineers got the Memo about NOT using pushrod engines on the latest 7.3 Godzilla engine for their newest F-250 thru F-650 medium duty line-up...