Fantastic essay

Why is it your English is so good BTW Patrick?

 

Well.. its now 18:54, some 18mins later and its now been viewed 3301times so thats 49views in only 18mins during the quiet tea time period in PassionFord's day...

Seems pretty popular pal

 

Thanks a a lot

I think ive mentioned it before, im a computer scientist basically. Ok, nothing special about that regarding languages, you think. But im what they call a computer linguist. I study languages when used by computers. How languages are constructed, how grammars, if there are any, is designed for natural languages. How to interpret a voice in a computer. The meaning of sentences, and making computers understand them. Besides this i study the formal languages, which include the creation of programming languages and the like.

Thanks again

 

God essay Patrik And yours too Stu (Not had a good chance at reading it in the FAQ as cant as im not a gold member )

Il have a proper read later when i get in

 

Ceramic coating was done prior to fitting, have tried to put the braces in the right place etc, will report back If/When it breaks again.
If it does break i will take it off & get you to sort it, no i aint kidding.
Rod

 

Ok. Well then it was a case of bad construction basically.

Haha, no need sending it all the way to sweden? Why me anyway? If this happens, mail me pictures of the pipe construction in many angles and views and i will help you the best i can mate.

-Patrik.

 

Didnt the Focus RS have a tubular manifold origionally ??

And if you beleive the hype the Focus RS's origional tubular manifold cracked under its heavy test schedule and to order a cast version to be designed from scratch and the cost that must of invovled so if they "Ford" cant get it to work 100% with all the money and technology they have @ hand, shows just how hard it is to do let alone of a huge BHP powered car

Interesting to see How Rod's last with the abuse it gets

 

While were on the subject of Turbo gas flow can we have an essay on pulse tuning turbo's with reference to how it works on a Nat Asp car and the differences encountered with turbo'd applications?

Ta

The rest of this thread is ace

 

no the man at cosworth said that the only way to make one 100% is cast and even that has its own life time
am not sayin he knows it all am just after more info the manifold i am doing at the min is going to crack i know it will it ways a ton aswell 4mm thick wall tube used but we will see
i much rather buy one off the shelve if i can but when you go to places and willing to pay Ł1400 and then they say no warrenty if it cracks i may aswell keep my own
cheers for the reply mike so if i bring my engine down to you you fit the manifold on the engine and brace it would you warrenty it then like you said on the fone
how much are yours mike pm me

 

Even Cosworth and Ford struggled with manifold cracking problems in the early development of our YB engines!!!

Just read this:

"The Cosworth Sierra turbo was mounted on the 1983-4 prototypes via a fabricated tubular steel manifold.

This was changed for a two-part nickel iron exhaust manifold casting in production. There were still severe *NVH problems that required the assistance of Southampton University, and turbo friction dampers to reduce to acceptable levels"

* Noise, Vibration and Harshness.

 

Now im lost

What all that mean?

Pulse Tuning Turbos?

 

I guess he means, considering tuning lengths and sizing of manifolds. But he expresses himself vaguely. Well. Is this interesting to the lot? I could write some of my views concerning this topic. Interesting?

 

itsme, surely the design of the mainfold will have an effect - 4-1 or 4-2-1 on the gas flow through the exhaust. You know how you can alter the primary tube length to alter the VE of the engine on nat asp cars. I don't know much about it so would like to know more but in relation to a YB

Sorry

 

i think he is on about n/a engine where you have a stepped inlet and exhaust ports to manifold to create a pluse or a wave length that pulled the gas out the port or into the port on the inlet recarding carbs or throttlebodys where you chance inlet track length to suit diffent powerbands

its going back a long way to my technicans course when i was yts so it could be a little mixed up i stand corected if it is

 

Thats it, I'm sure it can be applied to turbo'd cars too

 

Exhaust pulses are always there... Anyway, should i write something about it? The importance of design in NA versus turbocharged. What is important when designing the manifold for turbocharged applications and some other issues?

 

yes mr hex type away all you know i can still learn at 31
i kind of miss my yts training

 

Yes mate, please write away, VERY interested

 

Top thread

 

Ok, may take a while this one...

 

Is this any use, just found it http://www.eng-tips.com/viewthread.cfm?qid=23029

 

hexxon, you write some very interesting stuff. and it is amazing for me that you are reading and writing all of this in a foreign language. absolutely awesome.

i agree with a lot of the things that you have said so far, particularly on the isolating of the inlet manifold / plenum from the heat of the head / rest of the engine so that the incoming charge does not pick up heat and lose density after we've worked so hard to cool it after compression in the intercooler.

and also about keeping the flow path of the exhaust gases smooth to reduce turbulence and keep the gas speed high. on my own engine, i have paid particular attention when porting to open out the ports on both the head and the exhaust manifold (std cast 2wd item) to the same size as the gaskets to smooth the flow. all surfaces inside the manifold were also smoothed, as well as the elbow being matched to the manifold and turbine housing. i can't say what effect it has had as since doing it i have not optimised the mapping or even gone for anything larger than the std t3 at this time, but it's there for the future.

 

Thank you very much!

Well, nice that some are agreeing on my arguments, but its even more interesting to hear arguments thats against mine actually. Anything you dont agree with? It sounds like that

Well, gas velocity on the exhaust side is REALLY important... Glad more people understands this! Please, post any pictures!

 

Ok. There was interest in an essay regarding manifold design, considering design, pulse tuning and versus NA. So i thought i would just as well write my point of view briefly.

Lets start of with some basics. What does a manifold actually do? It evacuates gases right. Simple. So why not simply make a hole the size of a hangar? Well this is the tricky bit and what i will be talking about basically.

Manifold design, Turbo vs NA (Or blow me - Suck me) ::

NA(Naturally aspirated) engines can make use of what is called wave length tuned exhaust scavenging to temporarily easen the scavenging of the cylinder during overlap. This is basically peformed by optimizing lengths of manifold to generate scavenging effects at certain revs. This is possible because of the fact that ultra sonic sound waves, which are generated via the combustion chamber through valve cycles, creates negative pressure in the manifold when reflecting back and forth from a sudden increase of volume, such as the end of the exhaust system. These can be amplified using a number of methods. One of them is the method of using radiused, or stepped, piping. As this will be a comparison, to see the gains(or lack of) of using similar techniques as used on NA on turbocharged engines, i will not elaborate further on these subjects.

Turbocharged engines have a more or less large piece of engine converter at the end of the manifold. What this does is that it takes the kinetic and heat energy of the exhausts to accelerate a rotation of a turbine. This turbine is connected via an axle to an air compressor, which starts to rotate as fast as the turbine, leading to compressing more air, the more energy that is applied onto the turbine. So how about applying some wave length tuning then? Well, lets reason about it at first. We said that scavenging was performed using sound waves, right? So, what happens when a sound wave enters the turbo, into the turbine? Well, everybody who has heard the difference between fitting a 3" exhaust system onto a 2-liter NA-engine and a 2-liter turbocharged one, will figure out the puzzle. The turbine actually absorbs parts of the sound energy during the rotational acceleration of the turbine. This means, the turbo is part muffler part energy transmitter. This further means that optimizing for pulses will give very small, if any, results. Besides this, we have a positive pressure from the intake during valve overlap, which in itself LIGHTLY easens the scavenging of exhausts...

"What!? So theres no meaning in making a equal-length manifold for my YB?" If i would like to make it easy for me, i would just simply say no. But as im never gonna let it go as that, ill say in one way, in another not. Always being the troublesome one... What do i mean by this then? Lets think about what the turbine wants from the head, it wants a steady stream of gases, appearing with regular intervals, to produce the best acceleration given a cross sectional size of the pipings, right? Ensuring a steady strema will always improve the rotation evenly which is crucial for perfect turbine acceleration. "But this doesnt mean that we have to have equal volume in each of the primary pipes?" No, it doesnt. All we want is to have a steady flow. Thinking about the way a I4 ignites this would mean that it would be optimal to have the 1st and 4th cylinder connected to one pipe and then into the turbine housing, and the same for the 2nd and 3rd. This often produces a fairly large volume from the exhaust valve to the entrance of the turbo. The cons of this will be dealt with later. If we dont want this layout then, how should we do? Well, why not have equal length of the pipes from the 1st and 4th, paired up, as from the 2nd and 3rd, and then having them gathered just before the entrance? Well lets elaborate on the length issue i mentioned just earlier on.

Why ensuring a small length manifold? Earlier on in the thread we discussed backpressure. The backpressure caused by the cross sectional piping-size increases the longer the gases will have to travel. This is simple to understand. Blow air through a straw, will it be easier, considering lung-capacity, to blow through a straw whose length is 2 meters or one with the length of 3 decimeters? No, exactly. To relieve the engine of this kind of backpressure as efficiently as possible, short primary pipes is highly interesting. Now think about what manifold design that you want this far

Ok, lets consider some other design issues of manifolds for turbocharged engines. As mentioned in the essay dealing with backpressure, there is backpressure created from turbulence as well. What factors could produce turbulence in manifolds? Well, probably thousands, but i can come up with a few general ones quickly: surface quality, bend quality and join quality.

Surface quality is simply a measurement of how even the surface of the exhaust manifold is on the inside. Bumps, cavities and other drastic changes in the cross sectional area causes turbulence inside the piping. So what typically generates this, and what should we do about it? First of all, welds. Welds are, according to me, the devil when using it to construct flow-sensitive items. "You could always remove it using a grinder?" Yes, all of them but one on every damn pipe, that single last one... Besides this, theres two other factors making it unsuitable to weld sections of pipes, the risk of that, when welding two pipes together, getting one of them out of centre of the other, creates a border inside the pipe. The other one is that when welded, you will get an piping with uneven material characteristics. Some places harder than others, some place thinner than others. That is, some places more prone to cracking than others. "How is it possible to create a manifold without welding for the regular person then?" Bending. Mandrel bending the pipes as an example. Look at the possibilities there are in the industries today! "But how do you join the pipes together then?" Here, welding is one of the few ways of solving that problem, but as joining the fully mandrel bent pipes often occurs at the edges of the pipes, towards the head or towards the turbo, it is easy to perform any alterations such as porting, in an effective way.

Bend quality, what? Well consider this, to create as little turbulence, and counterpressure, as possible, the exhausts wants smooth passages. As wide radiuses on the bends as possible is the single most interesting argument on this one!

"Ok, ive figured it out, you are living in Utopia, and with one subject left?" Sure have. When joining piping to the head as well as joining them before the turbo, into whats called a collector, theres a huge number of factors that needs to be considered. Ill point out some basics. A cylinder head in aluminium expands more, due to heating, than a manifold made out of stainless steel. Theres a huge difference in increase of area. This needs to be counted for. Having a different cross sectional areas on two joins creates turbulence. Having the "outlet" smaller than the "inlet" is the least negative of the two choices, by far! Considering collectors, theres a huge amount of parameters to be counted with when joining together the primary pipes into one. Ill count some up. Relative angle of the primary pipes, length of collector and cross sectional area of collector. Another extremely important issue is the fact that having the collector joining the pipes in such a way that when the exhaust exits the primary pipe and enters the collector, as little turbulence as possible is created.

I will not go more deeply into these subjects as that generates some difficult calculations, and my idea with starting writing all about flow here, was to exclude any calculations, so that everybody could understand, more or less. Theres pages on the internet which deals with such calculations, search and you will find. This was atleast a brief description of some of the problematics of creating exhaust manifolds for turbochargers according to some basics of my theories of it all. Hopefully some finds it interesting!

ps. Didnt add anything of interest that one scruffy, thanks anyway ds.

 

breifly
wow am gona have a read later am buzy welding at the moment

 

Nice being up this late welding brom! You are sure up to it! Please send me any pictures, if you theres any available, on what you are up to! Guess you could teach me a thing or two on chassis for track racing... I am going to start modifying my other chassie, which will be the final one, in autumn next year... Its going to be some time put into that one, making all of the car, as well as my final engine, a really nice track day warrior. The nice thing is that you guys in england have a much greater interest in track-cars than most in sweden has got... I will probably be one of the few going all the way for track, and a tad extra on that one

 

just my wrc home made back end
theres a few posts knockin about
if you go on my photobucket theres loads in there
cozzybrom is my name on phot bucket

if i can help you in any way i will

 

Cheers mate, that sure is excellent to hear! The same to you, if theres anything you need help with, just tell me so, if you want my help!

 

Good read guys, keep it up

 

7 pages, no big rows?!?!?! is this a PF record?

 

one of the best topics ever on PF

 

ive got tooth ache feck does it hurt ps still a great post wish i understood it all more

 

work Patrik!

However, out of curiousity, if you perfected all these items on a 500bhp engine, how much extra power would you expect to release? 10, 15, 20, 25, 30 or even more bhp?

Don't worry, I'm only playing devil's advocate to get you to write some more . If it is only such a small amount, could this not be achieved more cost effectively with say a significant improvement in intercooler efficiency (such as Karl's / Danny's tri-Cossie cooler mod)?

What would you say is the ideal ACT temp and resultant EGT etc to achieve the best combustion process / gas speed compromise?

 

LEE WROTEexcactly what i was thinking

qaulity post guys, @ this rate ill be building my own manifold by xmas

 

Most of my questions i had locked away in my head have been answered


Big respect to all who have given there input and views

Thanks
Jano

 

You bring up a few quite interesting aspects of it here Mike. The reason for having a nicely balanced manifold on a turbocharged car is not primarily for maximum power, but for average power, getting the turbo going a lot earlier. If you are lazy, and just after maximum power, you just increase the pipe-diameter so that it weighs out the cons of all the bad construction issues. BUT, in this case, a slower spool-up will be present.

Charge cooling is a total different matter, a complete science that one as well, mainly due to flow, pressure drops and different ways of cooling air.

To make it easy for me, i will say as cool air IN as possible and as HOT air out. "Thats bloody hilarious!" Yes. ... Btw, god damn i like old english expressions... Anyway. Charge air should be as cold as possible to make the density of the air as high as possible, the temperature should always be above 0 degrees as it enters the plenum however. Otherwise, water condense will cause icing in the intake, which is terribly dangerous for an engine. Exhaust temperature should be as high as possible, based on that the components which it encounters can take the heat. Ive seen exhaust temperatures as low as 750 up to 1000. Wouldnt wanna own the engine doing 1000 degrees though, heard that the axle did fail in it, unstrangely enough. I believe a maximum EGT of 850 is fine for most engines. Its all a matter of laborating for the engine, as these parameters are very engine dependant, especially EGT.

 

Ha ha. The thread starter/owner. Sorry for me taking it over, more or less, at parts...

Great that questions find answers!

 

I see, so basically your modifications are designed to improve the "boost threshold*" of the turbo (*Steve will like that ).

Okay, say with the standard set up and using X turbo, where the boost threshold is 3500rpm (the point at which the turbo makes it's full boost), what improvements to this would you expect (or hope) to achieve?

 

Exactly. Well, doesnt everybody like that!?

I would probably see an 500 rpm drop easily there together with mapping... More is possible, depending on turbo and head. 500 rpm may not sound much, it is however if you think about it...

EDIT: By standard set up, you mean standard manifold or what?

 

Yes, I did mean that, as this is what most people are running .