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Re: Inlet Manifold Design

Post by gtv-racer »

Holymozes :shock:
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Re: Inlet Manifold Design

Post by maxiboy »

found these on line

looks ok for the gta except maybe a bit small
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Mats
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Re: Inlet Manifold Design

Post by Mats »

Looks too tight, when simulating my plenum it was obvious that the volume in direct proximity to the inlet runner is most important to flow. I.e. if there is no volume of air there will be less air going into the runner.
Looking at the picture above the last runner (on the left) is boxed in by walls in four directions three sides and a "roof". The other runner next to it will not help either. Just doubling the width and adding 2-3" after the last/before the first runner will help flow considerably. The height over the tunner is actually less important.
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Re: Inlet Manifold Design

Post by kevin »

If we talking front wheel drive this is good option . Look at the size of the pipe coming into the chamber and compare that with the above pics . You can't really guage how high the dome of the chamber is .
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Re: Inlet Manifold Design

Post by maxiboy »

thanks for the info Mat was thinking of something similar but bigger..

3.8 litres for a 3.22 and I guess bigger if I get the 3.6 to work...

the issue I have with the other picture is the shorter ram stacks.. ok for a full race 8000rpm/9000rpm full race monster but i think the existing ram pipes need another few inches for a road motor but didnt want to add bends so was thinking a big as possible inlet further away from the existing ram pipes with maybe an adjustable length for testing until I find the optimum given the space constraints


let me know what you think or if experience says different
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Re: Inlet Manifold Design

Post by 75evo »

Mats mentioned a good point about extending the plenum. Look at the plenum of the Ferrari F12.
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Re: Inlet Manifold Design

Post by maxiboy »

I was also wondering regarding volume does it matter if the extra volume is below the ram pipes so to speak

I understand the ram pipes will suffer if touching the roof of the plenum but if they where longer in a larger plenum would it effect the intake flow..

just wondering as my calculations seem to desire a longer than achievable ram pipe length but wanted to get a long a I could toward the bulkhead without adding further bends
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Re: Inlet Manifold Design

Post by Mats »

Check out my video: http://youtu.be/0ft7W_2PbYI

Notice how the air really stand still in the plenum and when the inlet valve opens gets sucked in very locally around the runner entry. It's actually flowing more from the sides than right above and that's why you need to have some space between the walls and the runner. The difference between having the runner sticking into the plenum rather than starting like a funnel right in the wall is very, very small. Usually you just design it which way is easier or if you have some packaging issues and need the volume.
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Re: Inlet Manifold Design

Post by maxiboy »

Thanks very much Mats will make the design easier in the long run
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Re: Inlet Manifold Design

Post by maxiboy »

after some stripping and measuring the inlet pipes on the 3.2 156 and different lengths between banks

around the 30mm mark..

so thinking on staggering the inlet ram pipes by the same amount to equal the pipes lengths up..

would this be an issue having an unequal length ram pipe or would this benefit the design overall

got some nice ram pipes sorted 46mm diameter

staggering them would leave the bell mouths complete also

opinions please if you would be so kind..
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Re: Inlet Manifold Design

Post by Saabretooth »

Hey Maxiboy, couldn't contact you on the other forum with your mailbox full,
you can reach me at saabretooth@gmail.com


ok, so with what you're doing now with the trumpets/ runners ....etc what can are you looking to achieve with that set up?


Also, now that I know what inlet pipes are, trumpets... what's a runner? or is it the same thing?
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Re: Inlet Manifold Design

Post by maxiboy »

being doing lots of research

the maths i,m using from a renowned engine builder gives me an overall intake tract length of 333mm and 381mm in total..

so going to try and achieve this and do some dyno testing .. but maybe end somewhere between the two..

will keep threads updated as i get further along..

this seems to be the tuned length of the inlet tract and going for a larger capacity too..

3,200 engine plus 20% or 3,700 plus 20%.. so again two different sizes needed..

this with a tuned exhaust system should be able to create a 7psi draw in the inlet manifold without the movement of the piston..

thats what i,m aiming for
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Re: Inlet Manifold Design

Post by kevin »

While I was in SA last week I heard the shrill from this motor with barrel throttles from Dawies engine at Glenwood . As the barrels open the aperture gets bigger from centre ( obviously) and does not have the turbulence of the butterfly in normal throttles .
I see Dawie is using these beautiful Newman cams . Checks the overlap on the lobes . Just what Jim has been preaching in his graphs . These cams come in over £1100 .
I think this car is coming to UK as a fun trackday car .
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Re: Inlet Manifold Design

Post by Duk »

So giving this old thread a bit of a rattle...............

What are peoples thoughts on the types of variable resonance manifolds and their effectiveness?

For a pair rather different exampes, Ferrari went from its previous dual length manifolds in the F360 and F430 to its divided plenum chambers with interlinking valves in the 458. These are obviously engines with both high operating speeds and with excellent power per litre.

Closer to home (Aus), Ford Aus went from its old dual length manifold that they started using in the early 90's to a divided pair of plenums, again with an interlinking valve, on their 4 litre straight 6s.
Having said that tho, Ford Aus weren't exactly quick to impliment changes. The dual length manifold was developed for the single cam, 2 valve per cylinder engine. That same basic manifold layout stayed on the twin cam 4 valve per cylinder engines that also sported dual continuous variable valve timing.
The long stroke Ford 4 litre is never shy of low RPM torque output, but is no revver and its specific power output isn't exactly impressive.
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maxiboy
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Re: Inlet Manifold Design

Post by maxiboy »

yeah i guess that has to be advantages of the duel length plenum but if they are outright power or more low down torque or just emissions or needed with variable cam shaft timing i,m yet to get conclusive facts..

i have ditched the manifold design for now as im going to run some home made itb's design and have so much on at the moment its taken a back burner
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