Making Inlet manifold

[Rob_DOHC]

I think most of the above manifolds would work better if they were tapered slightly down from the tb (like crazy cages),

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[Lloyd]

Originally Posted by Rob_DOHC

I think most of the above manifolds would work better if they were tapered slightly down from the tb (like crazy cages),

why?not a dig,just looking for your reasoning.

[Rob_DOHC]

Well, for starters car manufacturers do this (generally all) look the the rover manifold, skyline manifolds etc, cosworth swedish inlet......... they have losts more money than us for finding out what works and what doesn't

But the reasoning behind it has something to do with equal gas distribution and venturi effect as a tapered plenum is in effect a venturi.

As air travels down a straight tube (with ports in it) it looses gas velocity, so on cylinder no4 (closest to the tb on an rst) you have a large volume of air going pretty fast, however by cylinder no1 you have less air (used in other cylinders) and its going more slowely (energy has been removed from the system) so by the time cylinder 1 wants a gulp it has less to gulp from lol

By tapering the chamber as the gas moves down velocity is kept constant (the aim of the game), if you pass a known volume (in the same time) of air through a tube of large diameter the gas velocity will be low, pass that same amount of air through a smaller tube the gas velocity will be high, resistance to flow will obviously also increase.

But generally the effect is less prominent on a force fed car, and again 'generally' so long as you have at apsolute minimum 1 cylinder volume of air in the plenum you are sorted, some say 1.5 x volume of air available in the plenum.

This is pretty badly described and apart from being very far from the full truth may be inacurate. However it does give a rough idea of why they do it lol

But for what ever reason the boys who devolope this stuff normally have large pockets for research and im not going to argue. The best thing to do when you are designing things is unfortunately to copy things that work well and are proven.

But aside from what ever i have said i am not dynamics engineer and am sure apart from looking fucking class your manifold works very well and crazycage, i wish i could tig like you!
Rob,

[zetaboostboy522bhp]

trumpets make a hell of a difference with throttle response and would advise to use them if you can. why you guys using cosworth and cutting them up , buy them direct from jenvey £19 each , cast alloy which is very strong and comes in 45mm or 48mm which would be enough for 700+ bhp. area six inlets have been tested on a superflow flow bench and have over 1000 hours of testing thats why he calls them zero loss intakes because each cylinder flows equal amounts of air. i can say that ians inlets and the new jenvey inlet are the only 2 inlets that have had major dyno time on the flow bench which is why you pay that little bit extra!. also crazycage has the right idea and you could cause probs if each cylinder is not flowing similar amounts of air and cause lean running .
the cosworth manifold has the elbow mounted in the middle to spread the air flow more even.
area six inlet notice the tappered inlet and trumpet designs





now the new jenvey inlet , note the diffuser which tappers down which basically rams the air down to cylinder 1 , and also keeping the box section of the inlet which means it can flow more air.






jenvey have also just released a 70 mm diffuser for high powered engines and was tested on a 650bhp evo engine ,then they changed it for the jenvey inlet and made 730bhp with no extra boost ,just slightly modding the fuel to match the extra air flow, i personally think that a paying £1000 for a inlet that can give a 80bhp gain is a bargain.

hope this helps and gives you some ideas what can be acheived from a good flowing manifold

cheers paul

[gus]

so wish i had the room for that

it would be on now if i did

does the jenvey plenum fit with roller barrel t/b's (titan) ?

[AustenW]

Use the cast alloy 19mm air horns from Jenvey

DO NOT use the Jenvey spun ones as they will break and fall apart under boost as they are made from soft 1.5mm wall alloy

Been there and got the t shirt about 5 years ago

[gus]

whats the exact depth of the jenvey one please

[lacey]

hello. I aint read this all but i made my own in let on my car and from all the people i spoke to these are the things that i took into account. The old hart f1 415t plenium didnt have trumpets and they did they home work. Also the plenium its self can do with being the same size at both ends but the air should be fed in a tapered channel to fill the plenium even. Throttle body need a better ecu than a single throttle ie multi mapping .and there are some more bits to take in to account like volume in relation to the power you what. But i did put trumpets in my plenium and made them adjustable adjustable lenghts and put a water jacket on it to. Also take a look at the mis inlet and harrow cross inlet as they work very well. And the std cozy one dont work as good as some people think as it make big heat differences between cylinders

[zetaboostboy522bhp]

Originally Posted by gus

so wish i had the room for that

it would be on now if i did

does the jenvey plenum fit with roller barrel t/b's (titan) ?

you can buy the backplate unmachined so if you sent your roller barrel off to jenvey then i am sure they could match them up and its only £60

cheers paul

austen is the man to listen to as he pretty much helped design the jenvey inlet

[gus]

paul

if you get 5 mins could you measure the depth of it for me
im proper limited for space, the roller barrels will need a spacer made cos they dont do direct fit to cvh

[RS1HEN]

Originally Posted by zetaboostboy522bhp

cheers paul

fully appreciate that this is an awesome build, but is this actually for an erst?

[zetaboostboy522bhp]

Originally Posted by RS1HEN

fully appreciate that this is an awesome build, but is this actually for an erst?

thanks mate but no it was going in a mk3 fiesta that was fwd but the bodyshell needed welding and it worked out to be cheaper to buy a mk6 fiesta bodyshell from ford as i thought i would need a solid shell for 522bhp lol. as you can see its now in 4x4 formation as we are converting the bodyshell to take cossie transmission etc . i wanted to do something different with the car instead of sticking the cossie engine in as its been built since 2007. we are hoping for more power from the engine as we have the new inlet , 4 extra injectors , dry sump system and we are going to cap the boost at 35 psi (max) (522 bhp @ 30 psi). the engine was making a gain of 38 bhp per pound of boost added at 7000rpm so theres a few more horses to come (hopefully lol) and we are hoping to get the car to round 600+ bhp per tonne.

cheers paul


gus i will have a measure for you tomoz mate as i down the shed

[RS1HEN]

Originally Posted by zetaboostboy522bhp

thanks mate but no it was going in a mk3 fiesta that was fwd but the bodyshell needed welding and it worked out to be cheaper to buy a mk6 fiesta bodyshell from ford as i thought i would need a solid shell for 522bhp lol. as you can see its now in 4x4 formation as we are converting the bodyshell to take cossie transmission etc . i wanted to do something different with the car instead of sticking the cossie engine in as its been built since 2007. we are hoping for more power from the engine as we have the new inlet , 4 extra injectors , dry sump system and we are going to cap the boost at 35 psi (max) (522 bhp @ 30 psi). the engine was making a gain of 38 bhp per pound of boost added at 7000rpm so theres a few more horses to come (hopefully lol) and we are hoping to get the car to round 600+ bhp per tonne.

cheers paul

thanks Paul,
thought that you wouldn't have enough clearance for both turbo and manifold! i couldn't see it going in a road erst as is......


would be tight longitudelaly as well, lol

[Lloyd]

poor pics, but it looks better now its painted

[crazycage]

looks good that lloyd

[Lloyd]

Originally Posted by crazycage

looks good that lloyd

cheers, hopefully it will work as good as it looks .lol.
i was going to build it up and do a trial fit on the engine in the bay. but i cant find the elbow or the injectors .

[RS1HEN]

Originally Posted by Lloyd

poor pics, but it looks better now its painted

that looks really nice!
i can't see the throttle body tho

and what injector rail etc, is that?

again looks excellent, better pics!

[marky_g]

that jenvey inlet is the bollcoks

[Deltona1]

I just found this thread whilst looking for info on the Jenvey plenum, has anyone done any actual testing on equal port share of this manifold?