If There Were No Emissions Regs, Would A Six Speed Transmission Still Be "Necessary?"

[nicholastanguma]

Whether it's the DRZ400 or the Jeep TJ or the Samurai or the Land Cruiser or the HD Sportster or any other vintage-to-almost-modern vehicle with a five speed transmission it seems like the majority of operators are constantly clamoring for a sixth gear.

Each one of these mills has much power potential hidden away behind the factory's lean carb settings, restrictive exhaust, poor head flow, and low compression ratio.

Everyone knows that such factory machines have to be strangled a bit, often in fact a lot of bit, to pass the emissions regulations for the markets in which they're sold, and so no factory engine is truly at its peak performance level.

But if an engine is operating at its best capacity won't it be making enough broad spectrum power from idle to redline that a 5 speed tran coupled with higher final drive gearing would essentially be the same thing as a strangled engine that has to use a 6 speed to compensate for the strangled power?

I've read plenty of instances where doods with a six speed tran are wishing for a seventh.

 

[nicholastanguma]

Not everyone apparently, since I don't agree that emissions tuning "strangles" an engine.

What's great is how flat the torque curve is on a modern engine so you can run two (or more) overdrive gears and get really good fuel efficiency on the open highway while still getting stellar peak horsepower when you need to climb or pass.

I'll quote from my original post:

Whether it's the DRZ400 or the Jeep TJ or the Samurai or the Land Cruiser or the HD Sportster or any other vintage-to-almost-modern vehicle with a five speed transmission it seems like the majority of operators are constantly clamoring for a sixth gear.

 

[billiebob]

Yes

Multi speed automatics today, some with double clutches and all computer controlled do way more than just help control emissions. They keep the engine at peak rpm when you need power. The 8,9,10 speed automatics let engineers design for a very narrow power band, which is how engines produce real power. Boats, fire trucks, anything pumping will be tuned for far more power because the load and rpm never change. Engines like the first Corvette with a V8 and 2 speed poweglide transmission did nothing real well. With just 2 speeds the engine had to produce power from 1K rpm to redline. Today Corvettes produce power over a much narrower rpm range and they blow the doors of old school Corvettes, even the hottest ones from the 1960s horsepower wars.

Plus emissions and fuel economy are easier to improve when the transmission has many speeds.

When the Audi A8 introduced the 8 speed automatic it hit a top speed of 150?mph in 5th gear. After that it slowed down in 6th,7th,8th gears which were all designed as overdrives to reduce rpm, reduce fuel consumption, reduce emissions, deliver a quieter ride. Comparing todays multi speed transmissions to the old 3 speed automatics is like comparing disc brakes to drum brakes.

The same is true for manual transmissions. I love a CJ5 with a 3 speed stick but those old 1970s engines were anything but clean, efficient or powerful. They were incredibly tractable, torque from 500 rpm and power over 5000 rpm, you really never needed to shift, you could run in 2nd gear all day.

Actually, the reason manual transmissions are disappearing is because we cannot pick the correct gear near as well as a computer can. I think the base Ram Cummins is the only full size pickup with a clutch today. edit, nope even that one no longer gets a clutch.

 

[shade]

Regardless of emission considerations, an efficient drivetrain will deliver fuel economy gains - more range for your vehicle.
Having more gears available often results in better fuel economy.

How that fits in with "engine strangulation" is beyond me.

 

[nicholastanguma]

Yes

Multi speed automatics today, some with double clutches and all computer controlled do way more than just help control emissions. They keep the engine at peak rpm when you need power. The 8,9,10 speed automatics let engineers design for a very narrow power band, which is how engines produce real power. Boats, fire trucks, anything pumping will be tuned for far more power because the load and rpm never change. Engines like the first Corvette with a V8 and 2 speed poweglide transmission did nothing real well. With just 2 speeds the engine had to produce power from 1K rpm to redline. Today Corvettes produce power over a much narrower rpm range and they blow the doors of old school Corvettes, even the hottest ones from the 1960s horsepower wars.

Plus emissions and fuel economy are easier to improve when the transmission has many speeds.

When the Audi A8 introduced the 8 speed automatic it hit a top speed of 150?mph in 5th gear. After that it slowed down in 6th,7th,8th gears which were all designed as overdrives to reduce rpm, reduce fuel consumption, reduce emissions, deliver a quieter ride. Comparing todays multi speed transmissions to the old 3 speed automatics is like comparing disc brakes to drum brakes.

The same is true for manual transmissions. I love a CJ5 with a 3 speed stick but those old 1970s engines were anything but clean, efficient or powerful. They were incredibly tractable, torque from 500 rpm and power over 5000 rpm, you really never needed to shift, you could run in 2nd gear all day.

Actually, the reason manual transmissions are disappearing is because we cannot pick the correct gear near as well as a computer can. I think the base Ram Cummins is the only full size pickup with a clutch today.

Good explanation, thanks for your insight.

 

[CampStewart]

With variable valve and ignition timing todays gas engines have a much broader power curve than older designs of the same displacement.

 

[nicholastanguma]

How that fits in with "engine strangulation" is beyond me.

Vintage-to-almost-modern powerplants have much power potential hidden away behind the factory's lean carb settings, restrictive exhaust, poor head flow, and low compression ratio.

 

[shade]

Vintage-to-almost-modern powerplants have much power potential hidden away behind the factory's lean carb settings, restrictive exhaust, poor head flow, and low compression ratio.

If the goal was simply to get the most power for the displacement, and price, emissions, & fuel economy weren't constraints, I'm sure they could do better.

If someone wants to improve the performance of a modern engine, they can often do so by installing less restrictive heads & exhaust, use a custom engine management tune, all while staying within emission standards. I don't consider that strangulation, and if they want to go beyond that, they can take it up with the government.

 

[luthj]

More gears is almost always better, up to about 10 for most light vehicles. The new auto trans are very reliable, and fairly low weight, so there is no significant trade offs for moving to them, other than a bit higher cost. Though manufacturing has gotten cheaper, so making a 10 speed today costs less than making a 4 speed 25 years ago (in inflation adjusted dollars, accounting for miles per dollar).

 

[85_Ranger4x4]

1970's farm tractors with "it doesn't smoke too bad" level emissions had 12-16 speed transmissions... heck dad's '67 4020 has 8. Efficiency plays a big roll IMO.

I am happy with the 5 speed in my truck... although with low range I essentially have 10 gears.

 

[CampStewart]

Going past just the fact that anything "almost modern" doesn't exactly have a carb... nothing is going to have lean fuel trim because that would produce a ton of NOx which is a pollutant and would fail any emissions standards. If you look at something like a quarter century old Mitsubishi Montero with DOHC and dual plane intake it seems unlikely that the manufacturer would have spent a fortune building huge heads with four camshafts and a 20 pound lump of aluminum on top with two separate air intake paths and carelessly then leave horsepower on the table due to "poor head flow", restrictive exhaust and low compression ratio. There's presumably some peak horsepower the engine could have achieved with a dragster exhaust and knife-edge timing but we're not talking about peak horsepower in this thread we're talking about drivability. If you fast-forward twenty years from that 3.5L naturally aspirated V6 to a ~2017 Ford F150 naturally aspirated 3.5L V6 it only makes about 10% more torque from the same displacement (and still peaks way up at 4200rpm) despite the benefit of two decades of engineering and manufacturing improvements.

Id like to see a graph of the torque and HP curves of those two engines and their BSFC. I am not familiar with the technology in the ford 3.5 so I am assuming it has VVT?

 

[85_Ranger4x4]

Going past just the fact that anything "almost modern" doesn't exactly have a carb... nothing is going to have lean fuel trim because that would produce a ton of NOx which is a pollutant and would fail any emissions standards. If you look at something like a quarter century old Mitsubishi Montero with DOHC and dual plane intake it seems unlikely that the manufacturer would have spent a fortune building huge heads with four camshafts and a 20 pound lump of aluminum on top with two separate air intake paths and carelessly then leave horsepower on the table due to "poor head flow", restrictive exhaust and low compression ratio. There's presumably some peak horsepower the engine could have achieved with a dragster exhaust and knife-edge timing but we're not talking about peak horsepower in this thread we're talking about drivability. If you fast-forward twenty years from that 3.5L naturally aspirated V6 to a ~2017 Ford F150 naturally aspirated 3.5L V6 it only makes about 10% more torque from the same displacement (and still peaks way up at 4200rpm) despite the benefit of two decades of engineering and manufacturing improvements.

During the dark times of the 70's and early 80's... lean burn and crappy heads were a thing. Back when when you had 150hp 350's and 110hp 302's. Lowering compression, screwing up the timing and running as lean as possible were the quick fixes to get existing engines to meet new emissions regulations.

https://www.hemmings.com/blog/article/chryslers-lean-burn-system/

And yes, with cavernous chambers (to lower compression) and air injection ports in the heads, period cylinder head value is rated by the ton... for scrap.

The E7 heads on my 302 were $40 for the pair on craigslist like 8 years ago. 20hp bump from my factory E6 heads and since the E7's still suck in the grand scheme of things (JY's are full of 5.0 Explorers packing GT-40/GT-40P heads that are another 20hp yet) they are still virtually worthless.

Taking an old engine and "deleting" the emissions stuff would really wake it up. Set the timing right, ditch the tiny 2bbl/variable venturi/computer feedback/CFI thingie and throw an intake/4bbl on it and swap the heads from something out of the 60's (or better yet aftermarket) and they would really perk up... because basically under all that crap stuck on on a 1970's/80's mill for the most part it is still a 1960's shortblock.

 

[85_Ranger4x4]

Yeah then it comes down to figuring out just what in the heck we're actually talking about here.

None of the No Emissions Glory Days engines of the 1960s or whenever had 6 speed gearboxes... so if you look at a 1967 Chevy 350 (the first of those..) it was doing 300 horsepower and 380 lb-ft of torque.. I guess then the LS9 would be the "Darkest" of those times making 165 horsepower and 275 lbs torque in a late 70s/early 80s GM pickup.

But then if we go forward to the ones that do have "many-speeds" transmissions - and I think goes without saying they have the most sophisticated emissions control hardware - GM's 5.3L V8 is making 355 horsepower and 383 lb-ft of torque.

Plot twist, is that gross or net hp? Remember they changed how hp was measured in '72...

So how does emissions equipment necessitate more speeds on the transmission when at the same time these engines are both cleaner and more powerful than ever?

Am I missing something about the topic at hand?

No idea, I have never heard of anyone with a 5 speed truck actually wishing it was a 6 speed UNLESS they were asking for a creeper first gear which would do nothing to improve emissions.

In my world, 5 speed + low range = perfect creeper gear selection for offroading anyway.

 

[85_Ranger4x4]

Variable intake geometry and valve timing & lift, direct injection, improved materials tech (a plastic intake manifold doesn't need to be flow honed, has no casting flash and can be molded in the ideal size and shape with essentially no cost or weight burden) and manufacturing tech (tighter tolerances and better materials and better lubricants mean lower viscosity and less mechanical losses) ... have broadened the torque curve, which has improved driveability (the topic of discussion here) - but none of that results from or results in the premise of this topic - that somehow engines would make way more power if not for those evil beady-eyed tree huggers trying to undermine your masculinity through reduced engine performance.

In theory, yes.

Until bean counters start ripping the engines out of FWD cars and putting them in midsize pickups. My 30 year old 302 is rated about the same torque as the V6 in a Tacoma or Colorado... but at 2000+ less RPM. They have the tech to do it but they don't want to spend the bucks.

 

[nicholastanguma]

that somehow engines would make way more power if not for those evil beady-eyed tree huggers trying to undermine your masculinity through reduced engine performance.

Huh? This is Mods, you want Firside Chat, which is down the hall.