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PostPosted: Mon Mar 17, 2014 6:31 pm 
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TBI Slant 6

Joined: Sat Nov 12, 2011 10:04 am
Posts: 214
Location: Upper So. CA
Car Model: '65 Valiant 170 T5
What I was thinking was that by using a design of this type, both the turn and the two pieces, that by means of either different "top" pieces or intermediate pieces, or both, that runner length could be simply adjusted to suit any particular engine without creating a huge range of part numbers.

Could simply flange the runner casting and bolt it to the plenum casting. Set the runner casting's runner length to be as short as is ever likely to be used. Then supply bare flanges to bolt to both and allow the end user to tune the ultimate length of the runners by fabricating an intermediate piece of any specific length that they wish to try.

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PostPosted: Mon Mar 17, 2014 8:53 pm 
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Turbo EFI

Joined: Sat Feb 20, 2010 10:23 am
Posts: 1321
Location: N. Ga.
Car Model: 64 Valiant
I like the idea of it being adjustable, and for my design, im going to make the plenum removable so internal ram tubes can be changed out to adjust the final runner length instead of having to have to create different casting to change out. This will make it more cost effective and easier to fine tune since the tube lengths can be adjusted more precisely.

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PostPosted: Tue Mar 18, 2014 5:46 pm 
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TBI Slant 6

Joined: Sat Nov 12, 2011 10:04 am
Posts: 214
Location: Upper So. CA
Car Model: '65 Valiant 170 T5
Perhaps these explain better what I'm thinking.
Tunable length - straight:
Image

Tunable length - 90°:
Image

Tunable length - 180°:
Image

Can accomplish this with a pair of 356 castings and a pair of H2O jet cut 1/4" steel or aluminum plates. Let the purchaser buy the 1.5" OD tube in whatever flavor they want.

FWIW I cast-in some simple trumpets in the plenum:
Image

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Thom



Cross-threaded is tighter than Lock-tite


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 Post subject:
PostPosted: Fri Apr 04, 2014 3:46 pm 
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EFI Slant 6

Joined: Sat Dec 03, 2011 9:06 am
Posts: 295
Location: Clearlake, CA.
Car Model:
Im loving this thread guys! Really making me want to take up some welding and get some fab work going...

Reading through this though it sounds like there is a bit of confusion about injector size/ placement according to HP/RPM...

First off, in a factory fuel injected system the injector atomizes the fuel, not the incoming air, or intake runners. ALL multi-port injection systems place the injector as close to the valves as possible. The key is finding an injector from an application similar to the intake you are designing and detting the distance and angle as close as possible to the OEM location of the injectors. So different injectors will perform better or worse depending on angle vs distance to the valves. Also take into consideration the vast amount of modern cars that are utilizing direct-injection, in wich the injector sprays directly into the cylinder itself, again the injector atomizes the fuel, NOT the airflow. We are not talking carburetors, or even a wet manifold injection (TBI or similar).

Runner length, plenum size and shape are designed to equalize air distribution from one cylinder to the next, reduce turbulance, and reduce pumping losses due to internal pressures changing. Ultimately you would want to design a manifold the creates an even pressure and even scavenging across all cylinders, alot of the time this can be accomplished with a plenum that is larger at the front of the manifold and tapers slightly to the rear cylinders... Longer runners will aid in low-end power at the loss of throttle response and upper-end power, while a short runner will aid in immediate throttle response, you'll notice a slight drop in low-end power.

I did alot of reading and research on intake designs when I had my Volkswagen VR6, wich is a major victim of plenum design flaws due to its unequal length runners. (15* v6, uses one cross-flow cylinder head for both banks)
Image

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PostPosted: Mon Jun 02, 2014 1:26 pm 
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EFI Slant 6
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Joined: Wed Feb 02, 2011 12:00 pm
Posts: 345
Location: Tustin, CA
Car Model: 1965 Barracuda 'S' auto
Ntsqd's 1st example is just like mine. Ill use a plenum "turtle" to reduce the volume at the extreme runners in my convertible plenum cover. Question: can we adjust the length of the throttle body ram tube instead of the individual runners? Make a relatively short runner intake, then make the ram tube come out the back and run the length toward the front, where the tb mounts, making that the adjustable tube? Alot easier..?

84000/RPM=length. So 84000/5000=16.8 inches runner length, 8 inch intake runner plus 8.6 inch ram tube. Ideally the intake should look like an equal length header with equal tubes coming out if a central plenum, sort of like a fountain on its side. Shape of turns is not crucial as it is a dry intake. Probably not worth the effort as the peak rpm tune would be very peaky, great for a pump motor, not so juch for a car motor.

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PostPosted: Mon Jun 02, 2014 3:22 pm 
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Turbo EFI

Joined: Sat Feb 20, 2010 10:23 am
Posts: 1321
Location: N. Ga.
Car Model: 64 Valiant
I'm utilizing adjustable length ram tubes in my manifold design. The runners on a slant intake won't need to be curved since the engine is slanted and can yield an optimum runner length without having to do that. I'll post pics of the inside of mine or a generic representation once I feel the exact final design prototype isn't top secret anymore.LOL

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There's no such thing as too much cam....only not enough engine!

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PostPosted: Tue Jul 22, 2014 11:25 am 
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TBI Slant 6

Joined: Wed Apr 16, 2014 4:23 pm
Posts: 126
Car Model:
Any prototyped working units yet? Are you 3d printing for casting or prototyping..and are you running cfd simulation..theres alot left in plenum design to equalize pressure and flows into the runners by using a double plenum(cone over plenum) as well as a plenum shaped much like a open wheel cars intake "scoop" above the drivers head..why skimp out on a rectangular plenum..look at the plenum on a skunk 2 k20 honda manifold..that is an almost ideal plenum arrangement. I am also building a few intakes as well..both fabricated sheetmetal units as well as some lost foam castings..ive got my own ideas however based on many years in the "import game"...ive been around my fair share of 500+hp 1.8L 's..all of which carrys over to slants readily. With respect..i like seeing new product offerings for such an old design..keep at it. Your renderings are nice.


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PostPosted: Tue Jul 22, 2014 2:04 pm 
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Supercharged

Joined: Sun Jun 04, 2006 4:53 pm
Posts: 4295
Location: Gaithersburg MD
Car Model:
Does velocity of incoming air effect efficiency, hp or torque with MPI? Back in the day of carburetors, someone produced a dual plane intake manifold for most popular engines. There were two parallel runners for each cylinder. The idea was that with a progressive, staged throttle opening, the cross section of the runner was small with low throttle opening, thus keeping the velocity up. When opened the second throttle blade the second runner came into play. Gas mileage on my Toyota Corona went from 18 mpg to 24 when I installed one, and drivability improved. My guess is it must make little difference with MPI as I have seen nothing of this concept out there. It would require a 2 bbl staged TB. Maybe velocity effects atomization in a carb, but does nothing for efi. Thoughts here?

In any event, this is interesting. I would vote for making it AC compatible.

Sam

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PostPosted: Tue Jul 22, 2014 2:17 pm 
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Supercharged
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Joined: Sun Nov 03, 2002 9:20 pm
Posts: 13008
Location: Fircrest, WA
Car Model: 76 D100
Here is a thought- instead of a complete new manifold, why not a series of spacers that go between the head and the intake manifold that hold the injector bungs? Then the stock intake manifold could be used with an adapter for the throttle body. The stock exhaust manfild couldn't be used, but you wouldn't want one for a fuel injected application anyway. Londer manifold studs would be required, but that is pretty easy to accomplish.


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 Post subject:
PostPosted: Tue Jul 22, 2014 2:53 pm 
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TBI Slant 6

Joined: Wed Apr 16, 2014 4:23 pm
Posts: 126
Car Model:
Yes..intake velocity directly affects efficiancy even with mpfi..absolutely...where efficiancy is improved via plenum volume and runner dimensions determines where it is most efficiant..just like a carbed intake...mazda had variable length runners on some 20bs as well as the 26b 4 rotors..thestck telescoped out or in depending on computer imputs controlled by servos..much the way many new engines have dual runner intakes..one for low rpm efficiancy..the other for high rpm efficiancy.


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 Post subject:
PostPosted: Tue Jul 22, 2014 3:01 pm 
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TBI Slant 6

Joined: Wed Apr 16, 2014 4:23 pm
Posts: 126
Car Model:
Im really shareing here...but these are a valid option to consider as well...triumph tripple throttle bodies...injectors can be had to fuel in excess of 300hp...stacks to plenum are easily changed for length..and the throttlebody/injector could be place as close the the head as possible..either injector on the topside..or bottom side as i would personally spray towards the top of the port myself...
Image


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 Post subject:
PostPosted: Tue Jul 22, 2014 3:06 pm 
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TBI Slant 6

Joined: Wed Apr 16, 2014 4:23 pm
Posts: 126
Car Model:
Formula1 motors spray fuel towards the top of the port though the injector is outside or above the stack...eitherway..i tend to pay attention to those design details..


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 Post subject:
PostPosted: Tue Jul 22, 2014 3:08 pm 
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TBI Slant 6

Joined: Wed Apr 16, 2014 4:23 pm
Posts: 126
Car Model:
Also...itbs tend to tame very large camshafts..and throttle responce is second to none..


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 Post subject:
PostPosted: Tue Jul 22, 2014 3:15 pm 
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TBI Slant 6

Joined: Wed Apr 16, 2014 4:23 pm
Posts: 126
Car Model:
The itbs pictured are from a triumph 675..and measure 44mm id each btw.


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 Post subject:
PostPosted: Tue Jul 22, 2014 4:38 pm 
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Turbo EFI

Joined: Sat Feb 20, 2010 10:23 am
Posts: 1321
Location: N. Ga.
Car Model: 64 Valiant
Reed wrote:
Here is a thought- instead of a complete new manifold, why not a series of spacers that go between the head and the intake manifold that hold the injector bungs? Then the stock intake manifold could be used with an adapter for the throttle body. The stock exhaust manfild couldn't be used, but you wouldn't want one for a fuel injected application anyway. Londer manifold studs would be required, but that is pretty easy to accomplish.


Reed, I have threaded injector bungs in both steel and aluminum for those that don't have the ability to weld or access to one. The spacer can work, but I think it presents more challenges to tightening the intake and exhaust/header together.

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There's no such thing as too much cam....only not enough engine!

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