I ca somehow sense that @insightful must be a married man. Happy wife/happy life & all that.
Will do on the updates.
Well, I did have a wife…once.
OOPS in my 1st post i said only air & gas are pulled past the intake valves on GDI engines.
Should have said only fresh air & PCV vapors
I saw Rod Knox link about the Detroit Diesel V12, I drove one and was unimpressed. We pulled long doubles on the NY Thruway with 490 hp Detroit V12s and 425 hp straight 6 Cats. Legal gross weight was 143000 pounds and we overloaded them a lot. All of our drivers preferred the Cats. No amount of screaming down the hills or speeding on the level could make up for the time the Detroits lost going up hills,
I drove a 490 Detroit later pulling long doubles and ran out of fuel on a 375 mile trip with 2 full 80 gallon tanks.
That sounds simple…use a catch can for the PCV vapors… Gas doesnt touch the valves in a GDi engine… I can see the PCV to hit the valves but the fuel is injected directly into the cylinder under piston compression no less!
Blackbird
The 2 strokes, even the diesels, use cylinder porting for intake. There are no intake valves.
My previous Toro lawn mower was easily the best overall lawn mower ( I thought) because of it’s awesome suzuki two stroke. I live on the side of a mountain and knew it would die eventually and needed service I could not give it. So I ga e it to my son in Mass with one of those tiny flat lawns in a developement he could mow if he had to with hedge trimmers. So the mower will see more service.
It has been replaced by a 4 stroke, though heavier, has an aluminum deck to keep the weight close enough. It has some fancy throttle compensation or what ever function to raise the RPMs when it hits deep grass to make it feel as powerful as a two stroke. It has other features like a continuous variable speed personal pace ( like a cvt) handle…gee, I like it better then the two stoke. The south may rise again @Triedaq , but it will do it alone and without the smoke.
I had a Lawnboy and loved it,I just dont think 2 strokes will make it in cars now(but we do have Miller cycle engines)
I hate to think what another Uncivil war would do to this country,this time it would be total destruction as both sides are closer to parity"Make war no more!"
Two stroke lawnmower engines have their place. You have a hilly lawn…you either need a two-stroke…or a bigger engine with a pressurized oil system.
Two stroke designs have been trying to catch up to four stokes on pollution and economy for decades. What they lack is the four strokes’ much more precise ability to meter air in and exhaust out. The more add-ons used to achieve that, the less of an simplicity/cost/weight advantage a two stroke has. Just look at motorcycles - that’s where all of those would be even more important than with cars, but four strokes have pretty much taken over.
Oldtimer wrote “490 hp Detroit V12s and 425 hp straight 6 Cats. Legal gross weight was 143000 pounds”
That’s roughly 300lb per hp, vs a car or light truck at 10-25lb/hp.
I can appreciate the patience and focus it must take to drive such a rig.
The Chinese are re-engineering some old diesel 2 stroke technology.
The uniflow design has been around for quite a while. Fairbarks-Morse had a design with two crankshafts. Each moved one of the opposed pistons. These engines are pressurized air intake so excess air will still exit the exhaust during scavenging. All of these opposed piston engines have been of Diesel cycle design.
Problems I see off the bat are where to place the spark plug; throttling of the inlet charge; excessive exhaust retention on part throttle; getting a catalytic converter to work with excess oxygen; the operation of O2 or AF ratio sensors with excess oxygen; the oil consumption resulting from two sets of compression rings crossing charging and exhaust ports; the weight of two crankcases and crank shafts; and cooling of the centrally located combustion chamber. If one could get a stratified charge burn in excess air enviornment, that would be a step forward. The two crankshafts could be coupled with a variable timing gear like the present variable valve timing chain/gear train to allow some supercharging of cylinder. BTW does anyone have the oil consumption experience of a Detroit Diesel V8-71?
On the subject of turbocharged supercharged engines, consider the B17 Wright Cyclone, B24, and P47 double row Wasp. Each of the engines in these airplanes had a supercharger on the rear of the crankcase. The engine exhaust was routed to a turbocharger in the rear nacelle/empenage using waste gate technology for boost control. The turbo impeller compressed the inlet air. The air went through a air to air heat exchanger to a blow through injection carburator hence to the engine supercharger. These engines could be considered turbonormalized as the turbo mainly allowed use of sea level horse power at high altitude. The engine to envy is the R/R Merlin which had a two speed supercharger blowing into an air to coolant heat exhanger into the second supercharger into coolant cooled passages to the intake valves. I am going to have to research the location of the injection carburator – maybe someone knows.
Well enough for now. Keep the good work coming.
circuitsmith, Lol- Those were the most POWERFULL trucks I ever drove. I pulled long doubles for three years on the NY Thruway and Mass pike with a 300 horsepower R model Mack (672 cubic inch straight 6) and it did a fine job. This was in the double nickel days and it maintained 67-68 mph , dropping to 40-45 going over Indian Castle fully loaded.Many people pulled long doubles then with 250 Cummins and Macks. I retired in 1995.
Good luck finding a pressurized oil system for a walk behind mower. I bought a John Deere 3 years ago and it was the last one available outside commercial equipment in my area.
Good luck finding a pressurized oil system for a walk behind mower.
Really? I OWN one. You should specify oil pressurized SMALL walk behind mower.
If its that dang steep.maybe its time to leave it alone,before your feet end under the mowing deck
As I said, commercial equipment is available and nothing else.
As I said, commercial equipment is available and nothing else.
I guess it comes down to semantics. Toro has a commercial line of mowers and home line. I agree their 32" is expensive - Toro does NOT consider it a commercial lawnmower. I don’t know too many companies that would buy a commercial mower from Wallmart.
Thanks Blackbird, nothing I read mentioned when the injectors fired. I figured with 30 to 1 air fuel they must fire on the compression stroke. Must be some tough little injectors.
I see some guys even with conventional injection & a turbo are running the catch cans. I guess the turbo must put an extra load on the PCV system.
The more I read about the combination of the GDI & turbo the less I like the idea, but we did buy the Tiguan a couple of days ago & mama is very happy.
I’ll have to look at adding a catch can.