turbo intake manifold design

[abently]

I'm going to be honest here and say the gains are going to be negligable especially under Forced induction conditions. If you were entering a competition where there are set rules, then would I worry about re-Engineering the standard manifold.

Most "bell-mouths" now are actually on the plate itself, ie not-protruding anymore like your probably used to seeing.

Not to put you off or anything but you are seriously endevouring on a huge challenge espcially since this will be fabricated not cast or completely machined after CFD analysis.

Best advice I can give you if you seriously want to try this is drill and weld a nut onto each exhaust runner. To either run an EGT gauge or 02 Sensor and data log it, this way you can then make adjustments to the design to even the flow under dynamic conditions.

I might post some pics up later on of current IM designs which show how they now achieve a balanced flow without upsetting the harmonics therefore maximizing torque and power. Essentially its a horizontal cone with a slit in it attached to a plenum and the slit size has to be optimised either under CFD or trial and error along with the cone diameter and overall length. And this is ofcourse if you want to design something much better then Factory not something which "may" work better then the OEM manifold.

If you seriously still want to give it a go, let me know and I'll also post up a bellmouth design article for you.

[myne]

it would pay to keep harmonic vibratios in the back of you mind when using long ( more than 100mm) on a 4a inlet manifold.

They seem to have a harmonic problem due to port design ?? To be honest i dont know what causes it ( i wish i did ) all i can say is if you have read my rides thread ...... i know you have you would remember all the hassels i had with harmonic vibratios and plenums cracking .... This is not to say yours will but is something to consider with runner length.

FWIW my runners bell out (rolled the runner) and sit flush with the base plate..... What linden said is the best way to do it but not always the easiest and some times just not practical unless you want the best of the best.


P.S motor looks the goods.

Takai mentioned this a while back. I theorised that it might be the airflow breaking the sound barrier. Air does strange things as it crosses that barrier. Even Chuck Yeager, the first man to break the sound barrier said the plane shook violently as it approached the barrier, Not long after exceeding it though, the plane became smooth and quiet again.
I cant remember if it was inlet or exhaust, but he did the math and said later that I might have been right. It shows as a distinct drop in the torque figures at the same rpm on all 4A's. I cant remember the RPM either. Takai might remember better.

[myne]

On the topic of inlets, I'm assuming people have noticed that a lot of new cars have plastic inlets.
Have any 3rd parties started developing plastic inlets yet? I could imagine that they'd be easier to prototype and mass produce once the original mould is made - not to mention significantly lighter and cheaper. Getting the right length and correct bellmouths would be easier too - right?

[Joshstix]

I might post some pics up later on of current IM designs which show how they now achieve a balanced flow without upsetting the harmonics therefore maximizing torque and power. Essentially its a horizontal cone with a slit in it attached to a plenum and the slit size has to be optimised either under CFD or trial and error along with the cone diameter and overall length. And this is ofcourse if you want to design something much better then Factory not something which "may" work better then the OEM manifold.

This is what you consider to be current IM technology? A cone feeding hte full length of the plenum through a slit?

I guess the Audi Group B cars were a few decades ahead of their time

I've posted pics of this design before. Strangely enough it is not the design used by the Indy cars and GT sports cars that I have seen pictures of in the last few years. I do think it's a really cool concept but I don't have hte money to put into testing to figure out why it was used but then moved on from.

[Joshstix]

On the topic of inlets, I'm assuming people have noticed that a lot of new cars have plastic inlets.
Have any 3rd parties started developing plastic inlets yet? I could imagine that they'd be easier to prototype and mass produce once the original mould is made - not to mention significantly lighter and cheaper. Getting the right length and correct bellmouths would be easier too - right?

Kind of "plastic" you can buy off the shelf carbon fibre manifolds for some of the Honda engines in the US. E.G http://www.skunk2.com/engine-2.php?code=INCOM you need a big market to make the tooling worthwhile though I suspect.

[IH8TEC]

making it is not a problem, i've been working in aircraft structures bay in the airforce here, so can get the material, it's only time, and i have enough (95% of fabricating on my car i've done myself)

. someone mentioned to me that the point the torque is dropping off (around 5000rpm) is due to the intake manifold being "tuned length" for that particular rpm. i am running bluetop cams currently, but feel there should be more power in them. and also that the bigger throttle body will help alot,

i'm tending towards the bellmouths into the base flange with a variable radius, i'm also limited to some extent with runner length if i go for long ones, (i dont want to hit the firewall)

abently - i'd be keen to look at some of those designs if you dont mind.


ps, i'll post up tonight a thing in members ride with the car.

[-GT-]

If manifold runner length is 'tuned' for a particular rpm torque will increase around that point, not drop off, hence the point of 'tuning' it; why would you go to the effort if it's going to decrease torque!

[IH8TEC]

that does not make sense from my understanding of it :S

[abently]

abently - i'd be keen to look at some of those designs if you dont mind.

Here's the Bell mouth article. Its technical so probably best to print it out and read it over a coffee.

http://www.profblairandassociates.co...mouth_Sept.pdf

Joshstix, that design is still used by the WRC cars. Ford Focus Zetec >



IH8TEC, I know its hard, having personally done exhaust manifolds as well, but that collector really needed to be merged on a more vertical angle rather then at 90 degrees. It won't matter if your using mild-stock overlap cams, but will come into play if you need more cam later on for a bigger Turbo.

[IH8TEC]

IH8TEC, I know its hard, having personally done exhaust manifolds as well, but that collector really needed to be merged on a more vertical angle rather then at 90 degrees. It won't matter if your using mild-stock overlap cams, but will come into play if you need more cam later on for a bigger Turbo.

ok, yeah i didnt' make the manifold, that's an actiondan peice, but i know what your saying, if i ever go to a bigger turbo (highly possible) the manifold will be sold with turbo, and one with alot better design and bigger pipe size will be used. i hope that isn't so bad as to cause much more restriction than possible.

[30psi 4agte]

the transition into the ports and having a nice taper on the bellmouths are the bit you have to get right if you want it to perform well.

must have that bit right .....cos it goes like snot......when it goes

Jordan

[twentyEight]

This is what you consider to be current IM technology? A cone feeding hte full length of the plenum through a slit?

I guess the Audi Group B cars were a few decades ahead of their time

I've posted pics of this design before. Strangely enough it is not the design used by the Indy cars and GT sports cars that I have seen pictures of in the last few years. I do think it's a really cool concept but I don't have hte money to put into testing to figure out why it was used but then moved on from.

Is this similar to what you're talking about?

http://forums.hybridz.org/showthread.php?t=127863

[Joshstix]

Yeah that's the concept. That top pic is from and Audi Group B rally car. The lowere ones in the first post seem to be their diesel sports car engines and is the first time I've seen them with thst style of plenum.

[mic*]

Google helmholtz resonator. This is what a manifold runner acts like acoustically, im sure you'll find pages that provide formulae to get the right reflection tuning length. Im sorry i couldnt find the article iv printed off before.

Custom HDPE (high density poly-ethelyene) manifolds are not viable because there are generally injection moulded which works out ridiculously expensive until you make like 10 billion of them...

[twentyEight]

Google helmholtz resonator.

There's a thread on it here also...

http://toymods.net/forums/showthread.php?t=10184