Lister Engine Forum

Lister Engines => Listeroid Engines => Topic started by: Hugh Conway on December 27, 2020, 09:17:13 PM

Title: Listeroid intake porting
Post by: Hugh Conway on December 27, 2020, 09:17:13 PM
Ever so often, the topic of porting comes up. For what it's worth, I tried an experiment today.
This morning was a clean-up day for our daily driver listeroid. Mostly a going over with a rag to clean off all the oil that seems to coat everything after a time. In this case, the generator drive belt was slipping a bit with a combination of a film of oil on the flywheel and moisture from condensation ( it has been raining/fogging here for almost ever).
After completion of cleaning and then starting up, I thought a good time to spray a litre or so of water into the intake under load. After removing the intake silencer (Solberg air compressor  intake filter) I used a garden sprayer to apply just sufficient  water so that RPM didn't bog down. Sometimes a bit too much water caused an RPM drop, which led me to wonder just how much intake air flow obstruction would affect RPM. At the time the engine (with about 2300 hours on it) was fully warmed up and pulling a 2800 Watt load.
With a flat piece of sheetmetal, I gradually covered the intake adapter until there was an audible decrease in RPM or a visual indication of the fuelling rack opening more.  I was able to cover the intake just a bit more than 50% before there was any change at all.
This experience seems to indicate that improving the intake airflow by cleaning up the port makes little or no change in power output.
Interesting........
Cheers
Hugh
Title: Re: Listeroid intake porting
Post by: 32 coupe on December 27, 2020, 11:19:44 PM
Good job.
Reinforces what many smarter than me have said for years when the subject of porting
and polishing the heads come up in conversation.

Thanks for "the final word" on that subject.
At least in my mind.

Gary

Title: Re: Listeroid intake porting
Post by: gadget on December 28, 2020, 03:37:07 AM
Oh man, I'm at about 4500' elevation, it would be nice to find a few extra ponies
Title: Re: Listeroid intake porting
Post by: mike90045 on December 28, 2020, 04:28:45 AM
Oh man, I'm at about 4500' elevation, it would be nice to find a few extra ponies 

That would be the DIY turbocharged model :
https://utterpower.com/turbo_6_1.htm
Title: Re: Listeroid intake porting
Post by: gadget on December 28, 2020, 05:55:43 AM
Oh man, I'm at about 4500' elevation, it would be nice to find a few extra ponies 

That would be the DIY turbocharged model :
https://utterpower.com/turbo_6_1.htm

That is pretty cool. I'm curious as to the viability of a belt driven blower or maybe electric??? It shouldn't need much for only 5 HP
Title: Re: Listeroid intake porting
Post by: 38ac on December 28, 2020, 11:20:00 AM
Oh man, I'm at about 4500' elevation, it would be nice to find a few extra ponies
I don't know what you are running now but a 6)1 becomes an 8/1 with a change to aluminium piston and increase RPM. Also the stock bore is 114.5MM but India has 120, 127 or 130 MM bores as pretty much standard fare. Any of those will provide a nice increase. A change to the 034 type fuel pump will help governor responce with the larger bores and HP
Title: Re: Listeroid intake porting
Post by: guest18 on December 28, 2020, 12:46:04 PM
Before I purchased a Satyajeet GM-90 6-1 back in 2006 Mike Monteth showed me a head. The bowl of the intake side had extra metal casted in the port right under the valve. He explained that it’s in there to help create a swirling effect of the incoming air that enters the combustion chamber from the DI head. He said this helps with efficiency and not to remove the casting. He mentioned that removing it will reduce hp and efficiency and in turn make it burn dirtier.

These Listeroids and GM-90’s run so slow that in theory it seems that you would want to leave the ports small. Especially if your going to use propane or NG injection in the intake port.
Title: Re: Listeroid intake porting
Post by: 38ac on December 28, 2020, 06:38:48 PM
The Bamford Z series had a similar shroud but it was attached to the head of the intake valve, a very odd looking arraingment. The valve was kept from turning by the spring retainer so the shroud would always stay on the correct side.
Title: Re: Listeroid intake porting
Post by: gadget on December 29, 2020, 04:18:15 PM
I use to port cylinder heads for a living. I worked for a very well known person in the racing world and with very well known companies. I really enjoyed it, very rewarding work. Ask me anything you want on the subject.....

I have never heard of an engine that would not see an increase of air flow into the motor after smoothing things out. Now if its actually needed, that is another question. These motors may not be able to push enough fuel to see benefit. What I mean is, even with the crappy heads they have, there may already be plenty of air flow even at full load.

Try your test again at full load (4500 watts ?)and see if it starts to smoke.

Your test reminds me of the magic rag trick.

Title: Re: Listeroid intake porting
Post by: gadget on December 29, 2020, 04:30:26 PM
Before I purchased a Satyajeet GM-90 6-1 back in 2006 Mike Monteth showed me a head. The bowl of the intake side had extra metal casted in the port right under the valve. He explained that it’s in there to help create a swirling effect of the incoming air that enters the combustion chamber from the DI head. He said this helps with efficiency and not to remove the casting. He mentioned that removing it will reduce hp and efficiency and in turn make it burn dirtier.

These Listeroids and GM-90’s run so slow that in theory it seems that you would want to leave the ports small. Especially if your going to use propane or NG injection in the intake port.

I suspect the bump is there to reduce cross section and increase air speed at the location. It may have been a later add on to make up for a poor casting design. Port swirl will only help when fuel is mixed with the air as it comes in. Example would be port fuel injection or carb. If done wrong, it also can cause fuel to fall out of the air stream and thats a problem. Once the piston stops and starts to travel back up, every thing changes directions so how would port swirl help a direct injected diesel? The fuel gets sprayed in way later. For a IDI engine, there would be no benefit to a turbulent air flow coming in the intake since there would be no swirl in the prechamber. For direct injection, some diesels have a swirler cast into the top of the piston to mix the air just as the piston approaches the injector. It works really well. I believe it also helps direct the fuel away from the piston face.

You really never know though with out giving it a try. Problem is 99% of the people doing port work don't know what they are doing and can make it worse.

(https://imgur.com/IB4Z8Py.jpg)
Title: Re: Listeroid intake porting
Post by: gadget on December 29, 2020, 04:36:09 PM
Oh man, I'm at about 4500' elevation, it would be nice to find a few extra ponies
I don't know what you are running now but a 6)1 becomes an 8/1 with a change to aluminium piston and increase RPM. Also the stock bore is 114.5MM but India has 120, 127 or 130 MM bores as pretty much standard fare. Any of those will provide a nice increase. A change to the 034 type fuel pump will help governor responce with the larger bores and HP

I'm glad Gary talked me into getting an 8/1, that and he talked me out of an ST head and I went with the stamford clone. Its a really nice unit.

You all should at least clean the loose casting up in the intake ports. I pulled a piece off about the size of a BB with my fingers. That would keep any of the loose stuff from getting into the motor.
Title: Re: Listeroid intake porting
Post by: gadget on December 29, 2020, 04:37:46 PM
duplicate
Title: Re: Listeroid intake porting
Post by: guest18 on December 29, 2020, 06:58:23 PM
Gadget, most people that try doing porting without understanding or proper schooling normally mess things up. The GM-90 head has a J figure casted in the pocket underneath the intake valve. Its roughly 1/4" tall. I agree that it's there to increase air speed and in turn also helps with swirling effect. As I wrote, this would also aid in mixing a gas that's injected in the intake. These engines, including the CS listeroid's dont need large valves or porting. Doing so will reduce air speed and in some instances it will effect performance and efficiency. Now, if there is casting pieces that can break than yes, get it out. But otherwise most of the time it's best to leave it alone.

Brings back memories of the Ford Boss 302 and 351 Cleveland engines. The intake valves and ports were too large for street use. The engines would gas foul the plugs so often. They would not run right until you were over 4000 rpm they ran great over 5000 rpm. This was the reasons why a the Australian Cleavland heads became so popular. Smaller combustion chambers and intake posts. They work great on street performance engines. The Aussie's got it right.
Title: Re: Listeroid intake porting
Post by: gadget on December 29, 2020, 08:25:33 PM
Gadget, most people that try doing porting without understanding or proper schooling normally mess things up. The GM-90 head has a J figure casted in the pocket underneath the intake valve. Its roughly 1/4" tall. I agree that it's there to increase air speed and in turn also helps with swirling effect. As I wrote, this would also aid in mixing a gas that's injected in the intake. These engines, including the CS listeroid's dont need large valves or porting. Doing so will reduce air speed and in some instances it will effect performance and efficiency. Now, if there is casting pieces that can break than yes, get it out. But otherwise most of the time it's best to leave it alone.

Brings back memories of the Ford Boss 302 and 351 Cleveland engines. The intake valves and ports were too large for street use. The engines would gas foul the plugs so often. They would not run right until you were over 4000 rpm they ran great over 5000 rpm. This was the reasons why a the Australian Cleavland heads became so popular. Smaller combustion chambers and intake posts. They work great on street performance engines. The Aussie's got it right.

It would be interesting to see that head. Diesel heads typically have zero valve tilt which makes for a horribly bent port but it makes it easy to keep the combustion chamber flat.

If the lister has a volumetric efficiency of say .9 and displacement is 1.434L that puts air flow @650 RPMs at about 15 CFM. So every second your trying to cram in .25 CFM through that tiny port with a volume of say 1/10 that? That give you an idea how fast that air is moving through there.

That gives us about  2.5 CFM per Horse power. That is plenty of air in theory. Problem is, I doubt we are seeing .9 volumetric efficiencies, from the looks at these ports, I would guess more like .6 - .7 at best. Thats assuming correct valve timing.

That could be why listers can smoke a bit even though technically they should have enough air at heavy loads. So....in theory, if you can get a bit more air in there, you should see less or no smoke under full load and better economy under heavy/full load.

But how many of us are running under full load all the time? I'm guessing no one.
Title: Re: Listeroid intake porting
Post by: Hugh Conway on December 29, 2020, 11:08:44 PM
@ Gadget
"Your test reminds me of the magic rag trick."
I don't know what the magic rag trick is, but.......
A few years ago, I was running this same engine under load, for some reason, without the intake silencer.
For some other reason, now  unrecalled, I had a rag in my hand. It disappeared. The engine slowed for a beat or two, then continued on as if nothing happened.
Sucked in and through, never found any of it. Was that a magic rag trick???? It was quite funny in any event!
Cheers
Hugh
Title: Re: Listeroid intake porting
Post by: gadget on December 30, 2020, 12:25:04 AM
@ Gadget
"Your test reminds me of the magic rag trick."
I don't know what the magic rag trick is, but.......
A few years ago, I was running this same engine under load, for some reason, without the intake silencer.
For some other reason, now  unrecalled, I had a rag in my hand. It disappeared. The engine slowed for a beat or two, then continued on as if nothing happened.
Sucked in and through, never found any of it. Was that a magic rag trick???? It was quite funny in any event!
Cheers
Hugh

LOL, no thats not the trick but pretty funny no less....

The magic rag trick works like this;

You have a clogged carb. Get the engine running and rev it up as high as you safely can(usually on starting fluid) While holding the throttle, cover the opening with a rag till it just about dies and keep repeating if needed. The super high vacuum created can sometimes unclog blocked fuel passages in the carb.

It works on small engines too....sometimes. Its saved me a carb removal many times over the years. People love it when you go over the help them with there mower thats sat all winter with fuel in the carb and you fix it with a rag.....
Title: Re: Listeroid intake porting
Post by: guest18 on December 30, 2020, 01:47:05 AM
  :) Done that trick on my Honda Lawn mower engine for 3 or 4 years right after it was taken out of storage to start mowing. Just last year I finally had to replace the carb.

It works.
Title: Re: Listeroid intake porting
Post by: 38ac on December 30, 2020, 12:26:08 PM
Being an old hot rodder myself I certainly understand the thought patterns behind home brew gains from port modifications. Years ago there were some threads on here with all kinds of hypotheticals based upon spark ignition  racing engine theories that no more apply to a 600 rpm Listeroid than a 34a bra applies to Dolly Pardon. Cleaning up debris left by India doesn't need to be rehashed,, I don't think?  My gut on the port work deal is it would take a very a sophisticated set up with lots of instruments to prove any gain and and it would be trivial at best. As suggested those gains would also only be at the higher HP rating.
  As for a home brewed  porting test that would tell a much better story than smoke or eye ball inclinations a person could devise a means operate and hold the rack with the governor unhooked. Then apply a load and move the rack to give the desired RPM at that load. Then with an accurate tachometer, (or Hz reading if using a generator) start closing off the intake as Hugh originally posted. If said test does not lower the RPM until a significant portion of the intake is covered then port work will be a total waste of effort AT THAT RPM AND LOAD.   
Another area the book educated diesel hot rodders get lost upon is the fact that a diesel engine port is only handling air and it is drawing the same amount of air irregardless of load. The exhaust flow varies with load but the exhaust is seldom talked about.  Discouraging a person from experimenting is not my goal but a few basics need to be included if theory is going to be discussed.
Title: Re: Listeroid intake porting
Post by: gadget on December 30, 2020, 04:50:26 PM
Being an old hot rodder myself I certainly understand the thought patterns behind home brew gains from port modifications. Years ago there were some threads on here with all kinds of hypotheticals based upon spark ignition  racing engine theories that no more apply to a 600 rpm Listeroid than a 34a bra applies to Dolly Pardon. Cleaning up debris left by India doesn't need to be rehashed,, I don't think?  My gut on the port work deal is it would take a very a sophisticated set up with lots of instruments to prove any gain and and it would be trivial at best. As suggested those gains would also only be at the higher HP rating.
  As for a home brewed  porting test that would tell a much better story than smoke or eye ball inclinations a person could devise a means operate and hold the rack with the governor unhooked. Then apply a load and move the rack to give the desired RPM at that load. Then with an accurate tachometer, (or Hz reading if using a generator) start closing off the intake as Hugh originally posted. If said test does not lower the RPM until a significant portion of the intake is covered then port work will be a total waste of effort AT THAT RPM AND LOAD.   
Another area the book educated diesel hot rodders get lost upon is the fact that a diesel engine port is only handling air and it is drawing the same amount of air irregardless of load. The exhaust flow varies with load but the exhaust is seldom talked about.  Discouraging a person from experimenting is not my goal but a few basics need to be included if theory is going to be discussed.

Well said 38ac, your bra analogy really paints a nice picture. I'm just hoping to get 4500 watts at the gen head with my 8/1 living at 4650 ft above sea level. If the wife can't run her oven off the lister i'm in big trouble.....
Title: Re: Listeroid intake porting
Post by: guest18 on December 30, 2020, 06:41:09 PM
It might be tough to pull a continuous load without increasing displacement. Need to de-rate the engine about 14%. From calculations it comes out to roughly 6.88 hp.

Or try turbocharging.

And the cheapest option might be to get her a gas stove/oven. I think gas cooks better. :)
Title: Re: Listeroid intake porting
Post by: gadget on December 31, 2020, 12:39:08 AM
It might be tough to pull a continuous load without increasing displacement. Need to de-rate the engine about 14%. From calculations it comes out to roughly 6.88 hp.

Or try turbocharging.

And the cheapest option might be to get her a gas stove/oven. I think gas cooks better. :)

I may actually pick up a 16/2 down the road and use the 8/1 with the axial charger.
Title: Re: Listeroid intake porting
Post by: guest18 on December 31, 2020, 01:18:26 AM
An axial charger would be a nice project.
Title: Re: Listeroid intake porting
Post by: dkmc on December 31, 2020, 04:54:47 PM

What needs to happen, is we need to make Gale Banks aware of these engines. When he gets up off the floor from laughing, he might get interested out of sympathy and then you'll see him with a 50/1 engine on Youtube. He's put science and engineering to work regarding diesels. It would be a hoot...

https://www.youtube.com/watch?v=i6cR5Jx2UsM
Title: Re: Listeroid intake porting
Post by: veggie on December 31, 2020, 05:16:04 PM

I may actually pick up a 16/2 down the road and use the 8/1 with the axial charger.

I would love an axial charger on the crankshaft of my 6/1.
If you find a good source that does not require a second mortgage to purchase, let me know.

Here's a fellow that built one for his Listeroid. Nice compact unit.
https://www.youtube.com/watch?v=VyJYdHzwsy4 (https://www.youtube.com/watch?v=VyJYdHzwsy4)

Title: Re: Listeroid intake porting
Post by: gadget on January 01, 2021, 01:33:09 AM

I may actually pick up a 16/2 down the road and use the 8/1 with the axial charger.

I would love an axial charger on the crankshaft of my 6/1.
If you find a good source that does not require a second mortgage to purchase, let me know.

Here's a fellow that built one for his Listeroid. Nice compact unit.
https://www.youtube.com/watch?v=VyJYdHzwsy4 (https://www.youtube.com/watch?v=VyJYdHzwsy4)

How about a radial instead of axial? There was a guy on a youtube video that was putting magnets on the pulley faces of the flywheels and pulling some power directly off the flywheels. Its like a built in rotor. I wish I could find the vidoe. Its allot of magnets but they could be spaced. You wouldn't have to surround the entire flywheel with coils, just as many as you want for power.

Why not make your own?  The windmill guys have lots of good right ups. You could also go the scrap route.  I think the hover board motors are good for 600w's. I think the washing machine direct drive motors are pretty high output but i don't remember what volts they are wound for.
Title: Re: Listeroid intake porting
Post by: mike90045 on January 01, 2021, 07:58:04 AM
I started to build one from a kit, but got side tracked with life !
here's some DIY info
http://www.microcogen.info/index.php?topic=50.0
 *  best *  http://www.windsine.org/2017/02/07/listeroid-backup-generator/
https://www.engineeringforchange.org/solutions/product/piggott-axial-flux-alternator-wind-turbine/
http://www.green-life-magazine.com/green-energy/renewable-energy/listeroid-with-axial-flux-alternator-windsine-inc/
Title: Re: Listeroid intake porting
Post by: cujet on January 01, 2021, 09:51:46 PM
Of course, increasing RPM by a few can easily increase output by more than any porting changes could. We could measure volumetric efficiency and determine just how much improvement is possible. While not the same, Lycoming aircraft engines have similarly poor intake airflow setups. Yet, they operate with very good volumetric efficiency until max RPM of 2700.

Tuning the intake and exhaust with long tubes might provide some ram effect and raise the smoke limit a few watts.

Note: There are some tiny turbochargers Such as the VZ21, available on Ebay for about $110-140. They are absolutely tiny, and might be small enough to use on a 6/1. Maybe I'll purchase one...
Title: Re: Listeroid intake porting
Post by: gadget on January 02, 2021, 05:11:43 AM
In theory at a .9 volumetric efficiency, the 6/1 could produce 9 HP at 650 RPMs. Will never get that high with this type of head though.

But, if you can increase VE by just .1, you should be able to pick up about 1 horse. Maybe thats enough for someone thats need just a little bit more.

It would be really interesting to see how much better an original lister runs vs a clone. I can't imagine the port quality of an original cast head is as bad as these clones.

Maybe I will rig up a used airflow meter (5volt reference type) on my motor when I'm done and see what she's moving (how do I tell if my motor is female?) Now I wish I would of waited to port my head. Maybe I'll find another head to compare. My gen head is rated for 8.3kw so I have a large enough load to max my 8/1 out.

I'm surprised no ones mentioned running a horn ring.........I hope your all having a great new year.
Title: Re: Listeroid intake porting
Post by: 38ac on January 02, 2021, 11:48:39 AM
 When one takes a hard look at these heads there are two restrictions. The 90° turn which cannot be fixed and the way the seats are cut which can be fixed. I was to start working on the heads to increase flows the first thing I would fix is to unshround the valves. The way the seats are cut leaves the valve at the bottom of a deep 45° cut, totally against any notion of high flow past the seat.  When I put hard seats in these heads I move the top of that old seat back a bit and also open up the bottom to match the inserts I use. 
Title: Re: Listeroid intake porting
Post by: gadget on January 02, 2021, 04:33:47 PM
When one takes a hard look at these heads there are two restrictions. The 90° turn which cannot be fixed and the way the seats are cut which can be fixed. I was to start working on the heads to increase flows the first thing I would fix is to unshround the valves. The way the seats are cut leaves the valve at the bottom of a deep 45° cut, totally against any notion of high flow past the seat.  When I put hard seats in these heads I move the top of that old seat back a bit and also open up the bottom to match the inserts I use.

I don't remember much valve shrouding on these heads. You got me curious now, I may have to go out and look later.

I really think we need to look closer at a more accurate camshaft and timing. I suspect allot of these clones are making allot less power then rated due to camshaft issues more then anything. Especially on a long rod ratio motor.
Title: Re: Listeroid intake porting
Post by: 38ac on January 03, 2021, 01:48:42 AM
Shrouding may not be the technically correct term but the 45° seat angle starts at the deck and continues down past the full face of the valve and below it. The head of the valve recessed at .100 below the deck. Certainly not conducive to good flow past the valve,, or great seating either.
Title: Re: Listeroid intake porting
Post by: gadget on January 03, 2021, 04:08:44 AM
Shrouding may not be the technically correct term but the 45° seat angle starts at the deck and continues down past the full face of the valve and below it. The head of the valve recessed at .100 below the deck. Certainly not conducive to good flow past the valve,, or great seating either.

Ah yes, I see what you mean. Just curious, what kind of life are you seeing out of the factory seats? Are they prone to sinking?
Title: Re: Listeroid intake porting
Post by: cujet on January 22, 2021, 09:57:39 PM
In theory at a .9 volumetric efficiency, the 6/1 could produce 9 HP at 650 RPMs. Will never get that high with this type of head though. 

I don't believe that is correct. Can you show the math involved?

The Listeroid lends itself amazingly well to a direct measurement of volumetric efficiency. Simply take a known quantity of air and run the engine. Quick calculations with time it takes to consume the air and RPM will give a reasonably accurate answer.

My guess is that VE is pretty good, and that there is little to be gained with intake airflow management.

Combustion efficiency may be a factor in the smoke limit, and internal (and maybe external flywheel aerodynamic) frictional losses on a Listeroid do reduce output somewhat.
Title: Re: Listeroid intake porting
Post by: dkmc on January 22, 2021, 10:23:29 PM

I think valve timing and lift is worth the investment of time to research. Even if that means correcting back to Lister specifications as has been discussed before. But beyond stock specs, maybe there's a 1/4 horse or 2 to be had.
Title: Re: Listeroid intake porting
Post by: Hugh Conway on January 22, 2021, 11:47:37 PM
@Gadget
"It would be really interesting to see how much better an original Lister runs vs a clone. I can't imagine the port quality of an original cast head is as bad as these clones."

You got my curiosity up......I looked into the intake ports of my Dursley 6/1 and my JKSON 6/1 to compare. Opposite of what I thought, the JKSON has a smoother port. They are both somewhat rough, but the Lister is definitely the more rough of the two. Of course, this is just a comparison of 2 engines, we may see something different with a more broad range of comparisons.
Cheers
Hugh
Title: Re: Listeroid intake porting
Post by: 38ac on January 23, 2021, 12:40:35 PM
I still think ya'll is barking up the wrong tree screwing around with the ports in the OEM head. Those tiny valves would be the first thing to go in the trash of I was so inclined to mess with one. India has a nice part in stock for you. Its the direct injection head that is used on some of the large displacement engines. The valves and porting under them is much larger. When I have time I will take some side by side pics.
Title: Re: Listeroid intake porting
Post by: 38ac on January 23, 2021, 02:33:46 PM
Direct injection 18/1 head and valves compared to 6)1 valves.
Title: Re: Listeroid intake porting
Post by: 38ac on January 23, 2021, 02:42:20 PM
Bottom of DI 18/1 head and DI piston. This setup is available for 114MM bores, my very first Listeroid was a DI 6)1 Metro. You need head, piston, injector and fuel line. You can also upsize your fuel pump element to 8MM to take advantage of any increase in air flow you might get.

All this would be an interesting project for someone who wishes to spend the time to properly test and document the results. I don't have suchcuriosity. When I needed more power than my 6/1 I bought a twin 😊

Sorry for the lousy picture quality. Dropped my phone and cracked the camera lenses.
Title: Re: Listeroid intake porting
Post by: gadget on January 23, 2021, 06:52:23 PM
WOW 38ac, thats a pretty big difference is size. I'm starting to wonder if the original lister team was focusing on some modified atkinson cycle type gains with this motor. Less compression ratio(low intake volume) vs expansion ratio. Thats one thing I love about the motor is the RPM / HP vs Displacement. Leaves lots of time to absorb the energy and keeps the numbers high for such an old design.

You are right though, best way to get more power is to go with a twin. I'm picking up an 16/2 as soon as the budget allows for my gen head. Then I can use my 8/1 for my low RPM always on axial flux CHP. Who says you only need one motor? I missed that rule. I'll just tell the wife the other motor was getting lonely....
Title: Re: Listeroid intake porting
Post by: gadget on January 23, 2021, 08:40:25 PM

Atkinson cycle if anyones curious;
https://www.youtube.com/watch?v=z45fM2N-4C4
Title: Re: Listeroid intake porting
Post by: dkmc on January 23, 2021, 11:22:13 PM
Who says you only need one motor? I missed that rule. I'll just tell the wife the other motor was getting lonely....

Agree completely. I'm up to 3 at this point. And my GF even went on the trips to get them, and helped with loading.

38ac, The picture of the piston reminded me of the story of the old clock repairman. Customer brings in their non-working coo coo clock. The old feller takes the back off and shakes out a dead fly....He says "There's yer problem, the Operator's dead".
Title: Re: Listeroid intake porting
Post by: Hugh Conway on January 24, 2021, 07:11:04 PM
I ran across this on a vintage BMW forum. Relates to carburettor/intake manifold interface and roughness in the intake porting. Of course it is for a carburetted engine with a throttle body , not a diesel, so may not apply at all. Interesting never the less.
Snowing heavily here this morning, so I'm wasting time poking around the internet.
Cheers
Hugh

---------------------------------------------------------------------------------------------------------------------------
Mismatched bores are actually a good thing and we use them on our race car engines that have carburettors all the time. The physics is as follows:

1) Picture the column of air that is travelling down the carb throat when the intake valve opens, it is moving at quite a fast rate and is laden with fuel.

2) When the intake valve closes the column of air slams into the closed valve. "An object in motion tends to stay in motion"

3) The air now wants to "revert" back up the intake track. This is what is commonly called "reversion".

4) The amount of reversion, time, length, etc is quite dynamic and changes with throttle position, RPM, barometric pressure, etc etc.

We have found after years of working on racing engines that we can put this to work for us! A step in the intake manifold works in two ways:

1) A smaller manifold creates a lower pressure area under the step (in the intake tract) and the lower pressure resists going "back up" into the higher pressure area. We have also found that a larger manifold created positive turbulence and has the same type of anti-reversion benefit, but not as much.

2) It creates turbulence in the incoming charge and this is REALLY good. Yes, I said turbulence IS GOOD for intake tracts!

Years ago many engine builders were flowing their heads with complicated flow benches and new ways to make intake tracts as smooth as possible in order to (so they thought) get a better flow rate. We have one in the back of the shop collecting dust right now! This thinking is wrong. A bit of roughness on the walls of the intake tract breaks the boundary layer of the air. I.e. If you look at any aerodynamics book worth its salt you will see that when a flow is right->left (for explanation purposes) there is a VERY THIN boundary layer actually going the OTHER way (left->right in this case) on the surface of the object (in this case our intake tract). This reverse boundary layer is actually what creates disruptive turbulence and having a non-smooth surface helps break the boundary layer and increases flow rate.

I will not go further into the physics behind it and the "amount of roughness", and the "amount of turbulence", because it depends on a myriad of factors.

In other words, if you have a step where the manifold is SMALLER than the intake tract that is the best scenario. We have also seen that using a manifold that is larger than the intake holds benefits but not as much as the smaller one.

In other words, don't worry about it! :-)







Title: Re: Listeroid intake porting
Post by: gadget on January 25, 2021, 08:06:42 AM
I was taught crossing the boundary layer was a no no and one must keep the flow laminar. Now your telling me turbulence is ok at the boundary layer. I feel like I may have missed out by avoiding the port altogether..Oh well I'm married now and don't have to worry about getting turbulent in the port.