FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: jayb on January 21, 2016, 12:35:54 AM
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This is Jon Kaase with a plexiglass tunnel ram, watching the pulsing and fuel distribution in a race engine.
https://www.youtube.com/watch?v=7Iq1B-2paCs&feature=youtu.be
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That is cool. I volunteer Steve P's finger for some testing. If I know you, you've already started on the plexiglass FE intake ;)
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If he shows up at the next EMC with mannequin fingers in his intake ports, I'm just going to quit >:(
That is a cool video though. Lots more pulsating inside that short runner than I would have figured. Especially compared to what's visible at the bottom of the plenum.
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That was pretty fricken interesting...I had no idea it would be that "wet"
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thanks , berry interesting
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Yes, berry, berry interesting! I'm amazed at the wetness, for lack of a better word, of the plenum where some pretty massive droplets and even sheets of gasoline accumulated. One would think that the draw of the valves opening/closing would sweep all those loose droplets and sheets down into the runners. Guess not!
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The guy cracks me up.
Let's see what it looks and feels like if I stick my finger in there.
"Out of the box" thinking indeed.
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What gets me is the strength of the pulses; I had no idea they were that strong. When I switched runner lengths of the intake on my SOHC, I saw a huge power increase at the engine speed of interest, so there was evidence that the induction tuning really has a major effect. But to see Jon's finger snapping back and forth like that in the port really drives that point home.
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gives new meaning to the Visible V8. I think I would have stuck the trunk monkey's finger in the hole though.
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That is cool. I volunteer Steve P's finger for some testing. If I know you, you've already started on the plexiglass FE intake ;)
If I know Steve, he'd put his middle finger in there...
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Would be interesting to introduce some smoke of some sort to really see the flow pattern.
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I have been trying to tell folks for years that there is reversion in nearly every part of the intake tract. That fuel climbing up the walls is proof that the shape of the plenum is wrong on many sheetmetal intakes as well as the dual plane intakes. There was even reversion in the exhaust port with a circle of fuel stains after the EMC challenge tear down. Joe-JDC
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I would put some dye in the fuel, maybe red in one carb and blue in the other. Sort of a democrat vs republican social mixer.
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That fuel climbing up the walls is proof that the shape of the plenum is wrong on many sheetmetal intakes as well as the dual plane intakes.
That is what struck me too.
As 427 said also, I was surprised at how wet it was.
Due in part to the necessity of building a non perfect plenum and runner set up in order to see it better I would assume.
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More of what I find interesting is that which isn't so obvious. It appears to be a straight valve Windsor engine, likely running Jon's special side-cant heads. Meaning likely 400 CID max and an engine type that DIDN'T bring Kaase Racing to fame.
One can bet he has done similar plexi-box testing, ad inifinitum, to his famed Boss 429 based monster motors of way over 800 C.I.D. Gaining knowedge here on near 8,000 rpm pure race engines with way over 1" lift could easily mean a 100HP+ gain on 1,600-1,700 hp Pro engines. I guess as JDC hinted if one could eliminate reversion and make the liquid gas present more gaseous (finer?) one could pickup a lot of hp.
Put another way, I'd like to see the result of a similar tunnel ram test but with throttle bodies that only handle air and the fuel is added directly to the runners via injectors.....obviously EFI.
If most of that wild fuel separation in the plenum now goes away, wouldn't we expect a fair hp increase, a sharper throttle, etc?
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it always amazed me that how well & long an engine runs when starting it by just pouring gas down the carb throats when the carb is dry. just raw gas sitting in the intake.
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I was impressed when I saw this the first time as well. What caught my eye the most was just what Jay was talking about, the "ram effect" of the pulses in the runner when it got into the "sweet spot" for RPM. Basically ram tuning or 3rd harmonic tuning, whatever you want to call it... it was pretty evident with the finger getting pulled down hard at that certain RPM where the runner length was correct for that RPM. This is how race engines make more power and have well over 100% volumetric efficiency.
I too was amazed at the amount of fuel climbing the plenum wall and washing around everywhere. I thought it would be more of a mist or the fuel would be more of a "fog" being mixed better with the air (A/F ratio).
I am sure the plenum shape couldn't be more like normal just because it was made up out of flat sheet and more of an experiment for testing.
Certainly and eye opener!
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In the 70s 80s Volvo R-Sport
sold an intake for 36-36 Weber.
For the B20 Engine,that had
"Finns" on the plenum floor
To make a mist of the Liquid
Fuel it was said
It was the only 36-36 intake
That worked god
Other without the finns was hard
To tune over the Rpm span
Sputered and hesitated.on Low
Rpm
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That fuel separation is one of those concepts that make you go duh after seeing it live like this. You stand in a hurricane you get wet. No surprise oems went to EFI, then DI. Sure wasnt for the sake of making things complicated. You can bet they did similar experiments.
With all that said still impressive the power and efficiency that can be achieved with a simple carb. That kind of out of the box thinking may not be that unorthodox, sounds like good ol problem solving to me. Identify a problem, identify how a given system works to see what affects your problem and solve. There will be more than one way to skin the cat. Not always simple but always effective.
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"Put another way, I'd like to see the result of a similar tunnel ram test but with throttle bodies that only handle air and the fuel is added directly to the runners via injectors.....obviously EFI.
If most of that wild fuel separation in the plenum now goes away, wouldn't we expect a fair hp increase, a sharper throttle, etc?"
With fuel injectors, I would bet that fuel would still be sucked back into the plenum and lay on the bottom, if not coat the sides of the plenum after awhile.
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It was decades ago, but it was the biggest screw-up I ever had anything to do with in an industrial account. A paper mill requested I furnish an air-intake filter for a large Joy piston type air compressor. The inlet flange was to be a 14" ASME. I can't recall the CFM but the filter housing and piping were required to be an all stainless steel. I contacted my supplier and delivered what essentially looked like a giant mushroom that held a huge single cylindrical filter element. About a week after it was installed I was called to the mill to look at the filter housing that had a experienced cracking in numerous areas. Fortunately we had recently hired a new mgr at another location that came from the air compressor market. He advised me to give him the bore, stroke, pipe size, rpm and length of intake piping. I faxed him the info and called to see if he had received it. He'd already done the calculations and advised the "critical length" zone was 10'-14' and the filter housing was situated dead in the middle of where it should not be. I advised my customer to either shorten or lengthen the inlet piping x-many feet, returned the filter housing to the mfg who rebuilt it and returned it rush and it worked happily for decades. You'll notice in the PDF they even mention valve breakage.
When 14" pipe and large filter housings crack from intake pulses you can't help but think: "Man if you could tune to take advantage of those pulses".
http://www.industrialairpower.com/wp-content/uploads/2008/10/joy-wn-compressor.jpg
http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1110&context=icec&sei-redir=1&referer=http%3A%2F%2Fwww.bing.com%2Fsearch%3Fq%3Dcritical%2Blength%2Bcompressor%26src%3DIE-SearchBox%26FORM%3DIENTTR%26conversationid%3D#search=%22critical%20length%20compressor%22
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Here is an interview video with Jon Kasse. It first talks about engine masters for a while, then about the "finger in the runner" video posted above. Pretty interesting...
https://www.youtube.com/watch?v=69pr4_DRbZY
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Would it help if you ran some sort of beaters in that huge plenum to keep the fuel aerated? Two Kitchen aid beaters at each end of the box, 4 total, literally mixing things up, electric powered?
Would DI engines still have fuel backwashing up the intake ports out of the chamber?
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Smokey Yunick refered to the turbo on his 50+mpg fuel efficient car as a homogenizer...................
Years ago there was a company that sold gaskets with woven wire cloth spanning the ports. A flat section of cloth would certainly cause restriction, but deeply bowled cloth could arguably offer minimum restriction and still break up fuel droplets
http://www.hotrod.com/how-to/engine/hrdp-1009-what-ever-happened-to-smokeys-hot-vapor-engine/
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Would it help if you ran some sort of beaters in that huge plenum to keep the fuel aerated? Two Kitchen aid beaters at each end of the box, 4 total, literally mixing things up, electric powered?
Would DI engines still have fuel backwashing up the intake ports out of the chamber?
Yes, I believe even with direct port injection, some backwashing would occur. Consider Kaase's finger as it is pulled up AND down as the valve opens and closes. Pulsing is an effect of the valve's opening and closing at a rapid rate. When the valve is snapped shut, that column of air/fuel it still moving towards the backside of the valve at high speed. The collision to some extent causes backflow (or back wash) until the valve reopens.
As Jay mentioned earlier on "....What gets me is the strength of the pulses; I had no idea they were that strong. When I switched runner lengths of the intake on my SOHC, I saw a huge power increase at the engine speed of interest, so there was evidence that the induction tuning really has a major effect. But to see Jon's finger snapping back and forth like that in the port really drives that point home."
Adding longer or shorter ram tubes on an fuel injected engine, like his SOHC in the '63 Galaxie, is a well know tuning trick to essentially move the rpm band up or down, short being up, long being down. However, I never really thought about how a long ram tube (for low-middle range strength) would coincidentally keep more of the air/fuel suspension, and not just the air, closer to the intake valve. I'd venture that if the runners in the plexi-box were say twice as long as depicted even less of a sheet or wave of raw fuel would accumulate in the plenum section.
And yes, Yunick is still long dead as are many of his disproven theories. The good theories and facts did survive him but have since been supplanted or added to by facts modern race builders like Roush, Penske, Kaase and other giants of the trade have proven time and again.
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I wonder if that is some of the thinking behind the " McGee " valves from years gone by . google mcgee valve .
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Years ago there was a company that sold gaskets with woven wire cloth spanning the ports.
Don't look now but that's been prototyped and in development again.
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One of the greatest scams of all time, the wire mesh over the intake plenum. It's right up there with Yunick's error (or scam?) on the long rod theory. Here's what noted Ford Pro Stock engine designer and all-around drag race engine expert Darin Morgan has to say, with facts backing him up:
People put WAY to much importance on this preconceived " ideal rod ratio" idea. Rod ratio is not a primary consideration when designing an engine. You get the deck as short as possible so the piston does not come out of the bore. That gives you better manifolding which will make ten times the power any " ideal rod ratio" would net you. You shorten the pushrod and make the valve train stable above 9000rpm. You make the piston ring package as compact as possible to get the pin as high as possible and that will make for a light weight, balanced (not top heavy) piston design, THEN you decide what rod connects the piston to the crank. Its not magic, its simple mechanics. People look at what Smokey Yunick said and they take it out of context in my opinion. He said you should put the longest rod YOU CAN not the longest rod YOU CAN CRAM JAM OR MANIPULATE into the engine. I see people all the time screw up the engine combination to facilitate some preconceived ideal rod ratio and they wonder why the thing wont turn up and make power. The difference in the GM 358 NASCAR test engine from 5.250 inch long rods to 6.1 inch long rods was maybe 2ft/lbs and 2 HP. Not much to worry about. That satisfied the GM engineers that there is nothing there. Does a short rod make more TQ? Does a long rod make more top end power? It probably does but its such an insignificant amount, its not even worth messing with! If there was a major advantage or power gain in this, it would have been proven a long time ago and we could all put this to rest but no one has. I wonder why???????????
Darin Morgan
R&D-Cylinder Head Dept.
Reher-Morrison Racing Engines
1120 Enterprise Place
Arlington Texas 76001
817-467-7171
FAX-468-3147
Visit our web site at
http://www.rehermorrison.com
Darin Morgan
Top
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I'm confused Bob.
Why argue wire mesh with a rod length comment?
And I'm certainly nowhere close to as experienced as Darin Morgan but rod length (it would seem to me) IS a primary consideration when designing your engine. Piston height is kinda important no?
Sorry if we're heading off the intended thread path.
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I'm not conflating the two at all. Wire mesh stuff was right up there with magnetic fuel lines magically improving mileage. Debunked as were many other alleged mileage improver ideas.
Rod length is also one of those over-thought topics that also allegedly reduced reversion in an intake tract per Kaase's example plexi-box, dramatically increased hp and cured baldness as well! Morgan and others have since proved otherwise. If it's 50th on his list as he stated elsewhere in those wonderful Reher-Morrison racing engine articles, it should be the same on our "list." Just sayin'......
Point is: the reversion in the Kaase intake tract appears to be present regardless of rod length and a few other factors common to many engines. Perhaps a much longer runner length dampens the collection of sheets and drops in a common plenum. Save for more testing, we don't really know is this is the case.
http://rehermorrison.com/category/tech-talk/
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Ok gotcha.
Though I still think the amount of reversion seen in the video is in large part due to the see through material necessary to shape the plenum.
To use your line of thinking, it's a problem but not as big a problem as we see in the vid?
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A couple of observations from experience. The wire mesh in the intake gasket is a major airflow hindrance, and the same if used as a screen under the carb spacer. Darin Morgan is smart, but a couple of his statements are not proven in my experience. Roughing up a port after it is ported may increase horsepower because it actually removes more material making the port even larger, which always increases horsepower if the port shape is correct. The same effect would be even more horsepower if he or anyone else were to go back through the roughed-up port with a cartridge roll and smooth out the ports again, increasing the horsepower again. The net effect is more airflow will increase horsepower up to a point---until velocity is decreased. And as a final point, the intake valve slams shut every stroke, in effect starting and stopping the air/fuel in the port. Since there is no piston compressing the air at the carburetor side of the port, the air simply tries to escape/bounce back out the intake to atmosphere. The same is true in the exhaust, the exhaust is trying to get back towards the exhaust valve because for an instant, there is more atmosphere pressure on the column of exhaust in the system than the there is exhaust coming out of the cylinder. That is the effect you see on Jon's finger and it gets more severe with increased rpms. Ideally you want the column/port long enough so that the airflow will be pulsed to ramcharge the air column into the cylinder as quickly as possible the next time the valve opens. That is where the relationship of the piston/valve/camshaft lobe needs to be optimal for the airflow/cubic inches of the engine. There is more to be argued, but I will stop. Joe-JDC
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Ok gotcha.
Though I still think the amount of reversion seen in the video is in large part due to the see through material necessary to shape the plenum.
To use your line of thinking, it's a problem but not as big a problem as we see in the vid?
Yes, the amount of reversion may or may not be due in part to the odd, box-shaped see-through plenum. We really don't know though if this is the case.
It would be very interesting to see if a normally shaped plenum cast from some clear material does exhibit a lot less sheeting and droplet formation. Some aftermarket sheet metal tunnel rams do have simple flat, bolt-on plate carb tops. Replacing it with a sheet of Lexan would not be hard and would allow one to peer down at least into a running intake tract and see if things are better.
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There is more to be argued, but I will stop. Joe-JDC
Don't stop on our account Joe.
Personally speaking I will soak up anything anyone with your experience wants to say.
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Joe-JDC I believe you may have missed what I was aiming at regarding a flat mesh spanning an air-flow path vs an extended surface area mesh spanning the same air flow path . I'm not sure how it applies to a vapor, but in fluids and gasses restriction is considered marginal (the engineers can live with the differential increase) by adding additional surface area via adding pleats or a bowl shape to the mesh. Pictured you see a flat mesh and an extended surface area mesh cone both with the same cross section size (span of the passage).
I can see in an all out race motor anything in the port adds differential pressure/restriction but passing through a mesh could surely vaporize fuel droplets. Logic says you'd want the mesh obstruction to have as much surface area as possible: For example instead of one 2" dia mesh screen under each barrel of the 4V carb you'd run (8) 2"x1.6" with one in each runner. Then you could mess with angling the screen's to utilize more surface area and/or put bowls into the screens flat surfaces to increase the amount of media - surface area and void space.
. Re: The wire mesh in the intake gasket is a major airflow hindrance, and the same if used as a screen under the carb spacer. I believe anything you can do to shatter the fuel into mist nearly nixes any probability for the fuel to coalesce back into droplets. Don't forget modern production fuel injected motors use a wire screen to determine air flow mass for their computers to work with.
http://www.alchemprocess.co.uk/images/filter006.jpg
I think about actual droplet(s) of fuel having it made it all the way into the combustion chamber. They do not add to the A:F mixture in the chamber (lean) yet they pass out the exhaust as unburned (rich). When you have rivers of fuel like in Jon's video that's a textbook example of how that false rich/lean mess happens.
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Just my opinions here...
I really, really doubt that a properly shaped plenum would show any difference in the amount of fuel puddling on the walls and bottom. Think about the pulsing seen in the video, and how strong it was. Combine that with the fog of air/fuel in the intake manifold, and it seems to me that this kind of puddling is inevitable. People question whether or not there would be a difference between a carb setup and an EFI setup, where the fuel is injected in the runners, and I would say no. The pulsing is still going to be present, no matter where the fuel is injected above the valve. I think that maybe with a direct injection setup, the issue would be reduced, but not as long as the fuel is injected upstream of the valve.
Think about the way people tune for proper runner length in a sheet metal intake. Everyone is trying to tune for the third harmonic. What this means is having the third pressure wave arrive at the valve in time to aid in filling the cylinder. So, when the valve slams shut, the column of air/fuel in the runner and port, which was trying to move into the cylinder, has to stop, and the pressure at the back of the valve bounces off the valve and travels back up the runner. Once it gets to the plenum, it is reflected back down the runner and arrives again at the valve. That was the first harmonic. But the valve is still closed, so the process repeats, two more times. When the pressure wave arrives back at the valve the third time (third harmonic), hopefully the valve is now open and the pressure wave helps fill the cylinder with air/fuel. Kaase's finger in the video is showing those pressure waves.
Getting back to the original thought, with those pressure waves slamming back and forth along the intake tract, I can't imagine that injecting the fuel in the runner would make much of a difference in how much shows up in the plenum. Inside the plenum of the sheet metal intake on my SOHC, there are lots of fuel stains. Pretty sure there's all kinds of fuel running around in there at high engine speeds. And I don't care what the plenum is shaped like, with air changing direction so rapidly with the pressure waves, the fuel is not going to stay in suspension, and the plenum is going to get wet.
On rod length, I would completely agree with Darin Morgan's assessment; it just doesn't matter that much. What matters in a racing engine is a tight ring package, so that the piston pin can be as high up on the piston as possible, to reduce the tendency of the piston to rock in the bore. A lot of people will say that rod length reduces side loading on the piston during the stroke, which is true, but a high pin helps negate that issue from basic leverage. Also at least a half dozen knowledgeable people have told me that a short rod will pull the piston away from top dead center faster, and get the air/fuel column in the port moving faster as a result. The graph below, which has exaggerated rod lengths of 5" and 8", shows this idea:
(http://fepower.net/Photos/Posts/rodlength1.jpg)
However, putting in some actual numbers like what we normally use as FE guys, it is clear that stroke trumps rod length in this area:
(http://fepower.net/Photos/Posts/rodlength2.jpg)
Finally, I have also been told, again by multiple individuals, that big block Chevrolet ports can be larger because those engines have a shorter rod, and they pull harder on the ports as a result. The math doesn't really bear this out; see the graph below, showing a 427 Chevrolet and a 427 FE Ford:
(http://fepower.net/Photos/Posts/rodlength3.jpg)
Almost no difference there in piston position versus crank rotation.
Anyway, my advice is to forget rod lengths, and focus on heads, intake manifolds and headers, and cubic inches to make more power - Jay
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Really enjoy this.
Thanks
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The mesh/screen wire reduces flow. Period. When I was working with one of the factory GTP race teams that ported all the heads and intakes for Buick, we tested those screens to see if they would help fuel atomize in the tracts and product more power. On the flow bench with test equipment to show where the velocity is located in the ports, and measure the speed of the airflow in all areas of the ports, the screens killed/did not help, so they were abandoned. Removed screens and ran fast again. There were gaskets available for SBFs with the screens sandwiched in the gasket, and they hurt flow also. On the rod ratio argument, just putting the ring package as close to the top as possible, and the pin also, automatically increases the rod length to compensate. Yes, too big a port will respond to a shorter rod that pulls the piston off TDC quicker. There are crutches for lots of poorly designed parts combinations. Jon Kaase made that statement a couple of times in his answers. When I first started cutting 5.0 intake plenums apart for porting, I changed the length of all the runners inside the plenum housing. The modified plenums were dyno tested and magazine articles were written about the torque and hp increases the changes made. A short time later the Edelbrock RPM II EFI intake came on the market with very similar changes to their RPM intake. I believe that a tunnel ram intake should not have the flat under the carbs to create that low pressure area. That is just my opinion, and until I can weld aluminum well enough to make my own manifold, it will remain untried. Joe-JDC.
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Interesting that Jay's custom SOHC tunnel ram has fuel staining where it shouldn't, answering the question that raw fuel is flying around regardless. And yes, between Joe and Jay's answers,
it's apparent that it's the closing of the intake valve that causes the fuel fallout, puddling, etc.
Separating the fuel function from the air function would fix the problem yet direct injection of fuel to the combustion chamber brings up another host of problems, eh?
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I can't imagine that injecting the fuel in the runner would make much of a difference in how much shows up in the plenum.
Interesting video and discussion. Just a thought, no experience, not going to war over it.
I would have thought that a multipoint efi set up that that shoots a more precise, already more atomized fuel at the back of the hot inlet valve may show less (maybe not zero) wet fuel in the plenum area. The pulses would be still there but perhaps more vapour than moisture.
But then again maybe it would drop out again once it hit the cold plenum. Heck I don't know! :-\
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Joe, what you describe is how I made my FE tunnel ram. As small a plenum possible with no place to puddle. The runners weld together on the bottom and make a sharp V for the plenum floor and the area between the cards is humped floor and sort of hourglass shaped walls.
That was after consulting and some secret testing with a guy who I think was really onto something.
He built a sheetmetal intake for a 460, actually a couple, and real sheetmetal... steel! Just for testing and not for a car, if it worked it was going to made from aluminum. In the first intake it was discovered it was soaking wet inside. Then a whole bunch of epoxy was filled in to get rid of the many low pressure areas and no more puddles. That is how I shaped mine.
Then he wanted to take advantage of that puddling and cut the runners off and built another intake looking like a normal "Pro Stock" style. The floor wasn't flat though it had a V between the runners that collected fuel and a deep well below to store it, From that storage eight small tubes ran to each runner at the lower part. This was going to make legal fuel injection on a car that required a certain carb and was handicapped by a low hoodline. He hoped to prove it on the dyno and then his Superstock car before he was killed in a road crash.
That may or may not have worked but it'd be interesting to have seen the result.
I wonder if the factories know this already and that is why direct injection is becoming more common?
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Hood lines dictate runner shapes and designs to a large extent in today's engines, and as such, keeping the fuel out of the various shapes necessary to get the lengths necessary, and volume of air needed for the engine size dictated direct port injection as close to the valve as possible. Also, keeping the runners dry allow them to be much smoother inside, and easier to mold, made of differing materials that don't have to carry fuel and its inherent fire hazards. Lots to think about when designing an intake. Joe-JDC
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I had an opportunity to have a conversation with Curtiss Boggs several years ago when I was building my first sheet metal intake for my Bonneville Bike project. He had told me the goal of the plenum was to provide "clean" calm air for the intake runners in a race engine. So for me the first issue I saw in the video was a lack of raised ports coming off the floor of the plenum to help isolate "dirty air" (vortices) and fuel sheeting from influencing the runners. The second was the possibility that the carb set-up is to small causing a highly charged velocity of air fuel entering the plenum washing it out with "dirty air/fuel". As an example the use of enormous Throttle-bodies in efi systems now a days helps in solving the high velocity input issue into an open plenum. Very cool video