Among the goals for any intake is to provide even distribution to all runners/cyls with the least amount of restriction. I'm not an engineer, nor do I have any expertise in CFD testing/modeling ~ BUT......I allegedly have a brain, and, based on much of what I've read throughout this thread, I can't envision your design having uniform distribution, FlatOut. At the very least, I would think that an improvement could be had by angling the inlet tube toward the roof of the plenum ~ BUT......DUNNO!

I ASSume that the only way to validate equal distribution to all 8 cyls is by checking each exhaust stream with individual temp &/or O2 probes ~ OR.......(gasp) good old-fashioned sp/plug "reading". Have any of these diagnostic strategies been used to disclose UNeven distribution with your current GT-40 intake? Another potential prob I see with your "feed plumbing" is the quick 90° bend immediately ahead of the TB (??).

A common theme that seems to pop up throughout this thread is the "bang-the-incoming-air-off-a flat surface" strategy, in order to spread it out evenly for distribution to all the runners. In keeping with that philosophy, I can't help but feel that 93Pony's bottom-feed tunnel ram (using 4 individual tubes) offers the greatest promise for uniform distribution in a V8 manifold.

It's interesting (at least to ME) that ~ when the NHRA Pro Stockers were mandated to run EFI several years ago ~ Greg Anderson & Jason Line were extremely dominant in the class for nearly a year. Since all competitors were required to use the exact same Holley EFI components (TB, ECU, injectors, inlet pipe, & front inlet size/location).......it was retroactively said that their initial dominance (1-2 tenths) was due to the "top-secret" intake-manifold design specified by Jason Line (implemented by Tim Hogan).

Of course, the rest of the field ultimately "caught up" ~ BUT........I can't help but speculate that the alleged "superiority" of their manifold design had a lot to do with creating uniform distribution.

 

My thought on the "air smacking a flat wall theory" was the flat wall across from the inlet might do a similar job. Seems to top is the best choice from the other designs on here but I'm drawing a blank on how I could make something along those lines with what I have to work with. I'm sure it would be smart to just shelf this whole unit and buy something that already works but I'm not that smart and like making stuff.

 

That's a good looking upper. I have no clue on how it will perform. I hope you tackle the project and report back your findings. I like to believe that I could make something that would function like that. I am sure mine would now look as good.

Has the anemometer and leaf blower been validated with individual O2s or exhaust temps?

 

Maybe ~ BUT......most (if not all) of the "flat-wall smacking" designs depicted in this thread are using the wall opposite the runner inlets, as opposed to the adjacent wall. As said previously ~ I have no CFD or flow-bench experience, but my Spidy Sense is telling me that smacking the incoming air into the side/adjacent plenum wall isn't gonna yield the even distribution that you/we all desire.......DUNNO!

I'm curious about what you found/find lacking in the GT-40 manifold that you're presently using (?). OTOH, if you "like making stuff" and you have access to CNC machining equipment that can produce that breadbox base plate depicted in your CAD drawings.......I'd be curious to see how it performs in comparison to your existing manifold. <thumbup> Such a project is WAY beyond my abilities, lol.

 

Not by me, Russell! BUT.......lacking pockets deep enough to afford the exotic instrumentation needed to monitor the temp &/or O2 content of individual exhaust streams, I can only ASSume that the leaf-blower strategy/analysis would be better than nothing. Also ~ a little talcum powder dispensed into the L/B's inlet might provide a measure of visual evidence, lol.

 

I came across these images today of [1] A Judd/Honda V8 Indy-car engine (unknown vintage), and [2] an older Indy-car "effort" that are both intriguing. I'm gonna go out on a limb and ASSume that these folks know what they're doing with regards to even distribution to all cyls.

Note the huge plenum and heavily-tapered runners on the Honda engine. It also appears that the charge air is split into two paths/branches......with one entering the front(?) and the other passing underneath and entering from the opposite end.

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In opposition to the above "elegant" design, is an older engine pictured directly below. It was supposedly designed &/or assembled by Smokey Yunick (RIP) for A.J. Foyt's Joe-Leonard driven 1969 Indy car, that nearly won the race!! <eek>

It appears to have old-school Hillborn mechanical injection. An almost exact duplicate of this "log" manifolding was also used on the experimental AA/FD of Adams & Enriquez, whose engine is pictured last.

It sorta makes me wonder how such automotive geniuses as Smokey and Gene Adams could've come up with such "rudimentary" manifolding if it were counterproductive with regard to distribution & power potential. Especially with Smokey's engine, which was required to run at WOT for 500 miles!!

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You answered your own question. These engines are expected to perform in a very narrow RPM range. You tune it for that range and don't worry about the rest of it. They also didn't have the knowledge we do, they got data experientially and did what they could, if distribution was off they would tune the mech injection to deal with it.

 

Post above is very accurate on Intake Knowledge of those engines. Very common to have 8 different nozzles on mechanical injection in those days.

I had a typo FAT FINGER in my post #859 about the Accufab Car driven by John Mahovitz.
The number as shown in the video is a 5 second run not 7 second (typo) post.

People ran roots superchargers in most Drag Competitions in those days and left the
High-tech tuning for the Indy car teams.
Danny Jones, who worked in my building was the "Indy Car Guy" in the 1960s.
He later was the TECH Expert on Ohio George Montgomery's Twin Turbo Race Car.
The car the NHRA guys said leave the Turbo car at home, George, people want to hear the
noise from the zoomie exhaust.

Tom V.

 

Not much has changed with NHRA since "those days", Tom. The vast majority of forced-induction classes use superchargers (roots, screw, or centrifugal), in lieu of turbos ~ for which they've had a long-standing ill-regard. The very few that compete nowadays are in Pro Mod, "Super" classes, a few Stock Classes, and in one or two Comp Eliminator categories. Turbos are NOT permitted in any of the "Professional" classes.

The only exception that comes to mind was their acceptance of Buddy Ingersol's turbocharged 268 cid V6 Buick GN in Pro Stock for a portion of the '86 season ~ after which the other P/S competitors raised such a ruckus that they outlawed the combo. Buddy nearly beat Bob Glidden's 700 cid T-Bird in the final at the IHRA Fall Nationals in Bristol, but his car suffered a loss of power at the top end.......losing by about a car length (possibly due to a melted piston caused by poor distribution?? )



Any thoughts on the "dual-inlet" Honduh/Judd Indy-car intake (posted previously), with its huge plenum and funnel-tapered runners?

 

I like the way the box is Bolted to the bottom. Make the bottom is the Box has less than good distribution a new top can be made. With the larger engine bay of the truck he can build a taller box. How about side inlet into a 90° turn the air hits the top?

 

I'd toyed with the idea of twin air inlets opposing each other to force the air from one side of the plenum into the other, but I could not come up with a viable design that would provide 100% even distribution to each plenum feed. Again it came down to how much straight tubing I plumb between the last bend and the plenum inlet.

Another idea was to have 8 individual plenums, and 4 plenums feeding 2 cylinders 180 degrees apart in the firing order. Both presented packaging challenges but I believe that design would work.

 

LOL.....the "challenge" of achieving equal distribution becomes infinitely greater when you add firing order and packaging requirements into the equation ~ especially with V-ates (not so much with 6-cyl engines, regardless of inline OR V configuration). I suppose that the one "solution" MIGHT arguably be some sorta reversed tri-Y (quad-Y?) configuration.

Smokey was way ahead of his time by building his SBC Indy motors with not only reversed rotation (arguably helpful in "left-turn" racing) but also with "flat" cranks ~ like Ford's "Voodoo" engines ~ that yielded a firing order with "putts" that alternated evenly between the left and right banks. In addition to helping charge-air distribution, the "flat-crank strategy" also evened the exhaust streams to each of his twin turbos.

As for the ill effect(s) of having a turn in the "feed tube(s) just ahead of the plenum......I'm reminded of a strategy that I used about 4 decades ago with a ghetto carb hat that I made for a blow-thru setup on a 2.3 Ford Courier. I used a TurboCoupe manifold & turbo, an Autolite 2bbl carb, a Holley "blue pump", and a boost-referenced FPR. I initially made the hat so that the incoming air entered at 90°, fairly close to the top of the carb. BUT ~ in spite of having the power valve modded for boost, the AFR leaned drastically no matter how much I fattened the PVCR's or the jetting.

After some thought, I decided that the incoming air was disrupting the air bleeds and booster venturis, so I created a new/taller hat, as depicted below (please forgive the ghetto "pencil-CAD" drawing). The design change involved attaching a 3-4" tall homemade velocity stack to the choke horn while keeping the charge-air inlet low. Doing so caused the incoming air to slam into the sides of the velocity stack, travel upward to the hat's "roof", make a 180° turn, then go straight down into the carb inlet. All the AFR probs subsequently disappeared.

Anyway.......could a similar strategy possibly be employed in lieu of a curved 90° elbow, to provide an "even stream" of charge air without it stacking against the outside radius of the bend and getting biased towards one end of the plenum?

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FWIW ~ Since I may have caused some confusion (I have a way of doing that) regarding my analogy of the biased airflow exiting a curved pipe bend versus a potential "solution", using the strategy I employed in my former carb-hat.........perhaps the ghetto drawing below will clear it up?
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A company by the name SDCE was selling a cast aluminum hat with a 2.5 inch tall (if im correct) velocity stack. When i was testing hats, this was by far the best for equal distribution for air flow out of the carb. There was some bias of air flow on the back side of the hat. But not much. I believe a taller V-stack would have eliminated the bias.
I have since built a couple hats that I used baffles to control the air flow into the carb. Not too complicated. Smoke tested with a temporary clear top, watching air flow, and balance out of the carb. Just having a turn coming into the inlet has drastic effect on flow direction inside a hat. Of these two hats, both carbs work excellent and tune up is pretty equal cylinder to cylinder.

I like your 2nd gen.

 

YES......I remember reading a long thread here on The TurboForums about that hat several years ago, tbird. IIRC it was started by the owner of SDCE, who posted to expound its' virtues to the cumulative membership. Unfortunately, the thread quickly became a poop-slinging-fest, where most posters were talking about how "fugly" the hat looked in comparison to the conventional versions, along with how one or two examples had split/blown apart when a backfire(s) occurred.

Ultimately, in spite of fighting vigorously to defend the advantages of his design, I think the "SDCE guy" sensed the futility and the ignorance of all the impassioned naysayers ~ AND.......left the discussion with his tail between his legs. Too bad.......because, IMHO (and proven by your testing), his design is/was far superior to the conventional carb hats, with regard to distribution equality. OTOH, I got the impression that most of the responding blow-thru guys were more interested in looks than they were in performance or piston longevity!!

THANX for your approval/validation of my fugly/ghetto carb hat. It was cobbled together - at first - as a quickie experiment to validate my gut feeling that turbulence caused by the incoming charge air was the culprit in causing the instantly-lean mixture upon the onset of boost. And.......it worked!! I subsequently had to restore the jetting and PVCR's to nearly their original (N/A) sizes.

 

Now that you mention it, I do remember the SDCE guy here. Not sure if he was here because I mentioned the hat initially.

I agree, most seemed to not care that it would make tune up easier and lead to the motor making more power because of good distribution.

One thing I forgot to mention, my hats have a coarse flame arrestor at the center to smooth and equalize the air flow into the carb.

 

In testing our machine shop stated raised runners inside the plenum resulted in better airflow distribution on their 3000+hp engines.
I can absolutely see how putting them directly in the path of the incoming air from the TB would help airflow distribution as it would cause turbulence and kill much of the inertia of the incoming air.

 

Please forgive my ignorance, tbird ~ BUT......whaddaya mean by "my hats"?? Do you make/market a carb hat? LINK?

I was/am only familiar with the "flame-arrestor" strategy that's used in the Vortech Powerhat ~ which, according to what I THINK was a Richard Holdener test video, causes a slight but measurable flow restriction.

 

Are you referring to raising the runners at the floor of the plenum that lead off to the head ports, 93 ~ OR.....the 4 individual pipes that "bottom-feed" the plenum from the TB?

Since you've reentered this thread, I have a couple of questions about your previously-posted well-thought/elegant manifold design:

1. What prevents the air entering the TB from being biased towards 2 of the 4 bottom-feed tubes by the throttle blade? (OR......are you only concerned with WOT distribution?)
2. Since your testing revealed that "X" length of straight pipe (depending upon diameter) was/is required to negate flow-bias of the exiting charge air after a turn/bend.......how long is the straight portion of your feed tube ahead of the TB?

BTW, please don't take these questions the wrong way ~ they're not intended to impart any negativity toward your beautiful design.......rather, they're intended to help me gain knowledge from someone who has probably forgotten more than I'll ever know, lol!

 

Raised intake runner ports on a standard TB feed intake manifold, would not matter with the manifold I designed.

1. Air is baised to the long radius side before the TB and the 2 feed tubes on that side, there is little that I could do there. The design called for those 2 tubes to be in the first and 3 position (front to back), but the fabricator did not listen and put those 2 feed tubes in the front 2 positions. More over the TB had to be rotated 90 degrees due to a mis-measurement by the fabricator and this changed the throttle blade to vertical vs horizontal in the original design. To my surprise, airflow distribution at WOT was just fine like this. Part throttle is under vacuum in the plenum/runners, and I did zero testing for distribution of airflow under vacuum. Only WOT with high pressure/inertia.

2. Less than 6" due to packaging. I could do little in this area and therefor the manifold had to kill the inertial all on it's own. Hence the 9+" of straight tubing to feed the manifold, and the splitting of the single TB feed to 4 individual tubes. Smaller tubes need less straight length for airflow to redistribute evenly after a bend.