Ismetimo sistema (jos dydis) turbo varikliams

[spade]

Jay Kavanaugh, a turbosystems engineer at Garret, responding to a thread on
http://www.impreza.net regarding exhaust design and exhaust theory:

"This thread was brought to my attention by a friend of mine in hopes of
shedding some light on the issue of exhaust size selection for turbocharged
vehicles. Most of the facts have been covered already. FWIW I'm an
turbocharger development engineer for Garrett Engine Boosting Systems.

N/A cars: As most of you know, the design of turbo exhaust systems runs
counter to exhaust design for n/a vehicles. N/A cars utilize exhaust
velocity (not backpressure) in the collector to aid in scavenging other
cylinders during the blowdown process. It just so happens that to get the
appropriate velocity, you have to squeeze down the diameter of the discharge
of the collector (aka the exhaust), which also induces backpressure. The
backpressure is an undesirable byproduct of the desire to have a certain
degree of exhaust velocity. Go too big, and you lose velocity and its
associated beneficial scavenging effect. Too small and the backpressure
skyrockets, more than offsetting any gain made by scavenging. There is a
happy medium here.

For turbo cars, you throw all that out the window. You want the exhaust
velocity to be high upstream of the turbine (i.e. in the header). You'll
notice that primaries of turbo headers are smaller diameter than those of an
n/a car of two-thirds the horsepower. The idea is to get the exhaust
velocity up quickly, to get the turbo spooling as early as possible. Here,
getting the boost up early is a much more effective way to torque than
playing with tuned primary lengths and scavenging. The scavenging effects
are small compared to what you'd get if you just got boost sooner instead.
You have a turbo; you want boost. Just don't go so small on the header's
primary diameter that you choke off the high end.

Downstream of the turbine (aka the turboback exhaust), you want the least
backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe
if you can. The general rule of "larger is better" (to the point of
diminishing returns) of turboback exhausts is valid. Here, the idea is to
minimize the pressure downstream of the turbine in order to make the most
effective use of the pressure that is being generated upstream of the
turbine. Remember, a turbine operates via a pressure ratio. For a given
turbine inlet pressure, you will get the highest pressure ratio across the
turbine when you have the lowest possible discharge pressure. This means the
turbine is able to do the most amount of work possible (i.e. drive the
compressor and make boost) with the available inlet pressure.

Again, less pressure downstream of the turbine is goodness. This approach
minimizes the time-to-boost (maximizes boost response) and will improve
engine VE throughout the rev range.

As for 2.5" vs. 3.0", the "best" turboback exhaust depends on the amount of
flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power
level won't get you much, if anything, other than a louder exhaust note. 300
hp and you're definitely suboptimal with 2.5". For 400-450 hp, even 3" is on
the small side."

"As for the geometry of the exhaust at the turbine discharge, the most
optimal configuration would be a gradual increase in diameter from the
turbine's exducer to the desired exhaust diameter-- via a straight conical
diffuser of 7-12° included angle (to minimize flow separation and skin
friction losses) mounted right at the turbine discharge. Many turbochargers
found in diesels have this diffuser section cast right into the turbine
housing. A hyperbolic increase in diameter (like a trumpet snorkus) is
theoretically ideal but I've never seen one in use (and doubt it would be
measurably superior to a straight diffuser). The wastegate flow would be via
a completely divorced (separated from the main turbine discharge flow)
dumptube. Due the realities of packaging, cost, and emissions compliance
this config is rarely possible on street cars. You will, however, see this
type of layout on dedicated race vehicles.

A large "bellmouth" config which combines the turbine discharge and
wastegate flow (without a divider between the two) is certainly better than
the compromised stock routing, but not as effective as the above.

If an integrated exhaust (non-divorced wastegate flow) is required, keep the
wastegate flow separate from the main turbine discharge flow for ~12-18"
before reintroducing it. This will minimize the impact on turbine
efficiency-- the introduction of the wastegate flow disrupts the flow field
of the main turbine discharge flow.

Necking the exhaust down to a suboptimal diameter is never a good idea, but
if it is necessary, doing it further downstream is better than doing it
close to the turbine discharge since it will minimize the exhaust's
contribution to backpressure. Better yet: don't neck down the exhaust at
all.

Also, the temperature of the exhaust coming out of a cat is higher than the
inlet temperature, due to the exothermic oxidation of unburned hydrocarbons
in the cat. So the total heat loss (and density increase) of the gases as it
travels down the exhaust is not as prominent as it seems.

Another thing to keep in mind is that cylinder scavenging takes place where
the flows from separate cylinders merge (i.e. in the collector). There is no
such thing as cylinder scavenging downstream of the turbine, and hence, no
reason to desire high exhaust velocity here. You will only introduce
unwanted backpressure.

Other things you can do (in addition to choosing an appropriate diameter) to
minimize exhaust backpressure in a turboback exhaust are: avoid crush-bent
tubes (use mandrel bends); avoid tight-radius turns (keep it as straight as
possible); avoid step changes in diameter; avoid "cheated" radii (cuts that
are non-perpendicular); use a high flow cat; use a straight-thru perforated
core muffler... etc."

"Comparing the two bellmouth designs, I've never seen either one so I can
only speculate. But based on your description, and assuming neither of them
have a divider wall/tongue between the turbine discharge and wg dump, I'd
venture that you'd be hard pressed to measure a difference between the two.
The more gradual taper intuitively appears more desirable, but it's likely
that it's beyond the point of diminishing returns. Either one sounds like it
will improve the wastegate's discharge coefficient over the stock config,
which will constitute the single biggest difference. This will allow more
control over boost creep. Neither is as optimal as the divorced wastegate
flow arrangement, however.

There's more to it, though-- if a larger bellmouth is excessively large
right at the turbine discharge (a large step diameter increase), there will
be an unrecoverable dump loss that will contribute to backpressure. This is
why a gradual increase in diameter, like the conical diffuser mentioned
earlier, is desirable at the turbine discharge.

As for primary lengths on turbo headers, it is advantageous to use
equal-length primaries to time the arrival of the pulses at the turbine
equally and to keep cylinder reversion balanced across all cylinders. This
will improve boost response and the engine's VE. Equal-length is often
difficult to achieve due to tight packaging, fabrication difficulty, and the
desire to have runners of the shortest possible length."

"Here's a worked example (simplified) of how larger exhausts help turbo
cars:

Say you have a turbo operating at a turbine pressure ratio (aka expansion
ratio) of 1.8:1. You have a small turboback exhaust that contributes, say,
10 psig backpressure at the turbine discharge at redline. The total
backpressure seen by the engine (upstream of the turbine) in this case is:

(14.5 +10)*1.8 = 44.1 psia = 29.6 psig total backpressure

So here, the turbine contributed 19.6 psig of backpressure to the total.

Now you slap on a proper low-backpressure, big turboback exhaust. Same
turbo, same boost, etc. You measure 3 psig backpressure at the turbine
discharge. In this case the engine sees just 17 psig total backpressure! And
the turbine's contribution to the total backpressure is reduced to 14 psig
(note: this is 5.6 psig lower than its contribution in the "small turboback"
case).

So in the end, the engine saw a reduction in backpressure of 12.6 psig when
you swapped turbobacks in this example. This reduction in backpressure is
where all the engine's VE gains come from.

This is why larger exhausts make such big gains on nearly all stock turbo
cars-- the turbine compounds the downstream backpressure via its expansion
ratio. This is also why bigger turbos make more power at a given boost
level-- they improve engine VE by operating at lower turbine expansion
ratios for a given boost level.

As you can see, the backpressure penalty of running a too-small exhaust
(like 2.5" for 350 hp) will vary depending on the match. At a given power
level, a smaller turbo will generally be operating at a higher turbine
pressure ratio and so will actually make the engine more sensitive to the
backpressure downstream of the turbine than a larger turbine/turbo would. As
for output temperatures, I'm not sure I understand the question. Are you
referring to compressor outlet temperatures?

The advantage to the bellmouth setup from the wg's perspective is that it
allows a less torturous path for the bypassed gases to escape. This makes it
more effective in bypassing gases for a given pressure differential and wg
valve position. Think of it as improving the VE of the wastegate. If you
have a very compromised wg discharge routing, under some conditions the wg
may not be able bypass enough flow to control boost, even when wide open. So
the gases go through the turbine instead of the wg, and boost creeps up.

The downside to a bellmouth is that the wg flow still dumps right into the
turbine discharge. A divider wall would be beneficial here. And, as
mentioned earlier, if you go too big on the bellmouth and the turbine
discharge flow sees a rapid area change (regardless of whether the wg flow
is being introduced there or not), you will incur a backpressure penalty
right at the site of the step. This is why you want gradual area changes in
your exhaust."

[Conan]

Jay Kavanaugh, a turbosystems engineer at Garret, responding to a thread on...

tipo kanka bet gera

[spade]

Kankos cia pas autosus...
O cia sita tiesiog senuose seivuose radau, tai imeciau

[Minde_Kei]

aciu labai laiku

p.s. gal dar tokiu kanku?:)

[Fiend]

Idomus straipsniukas..
Hm, idomi mintis del hiperbolinio ishplatejimo nuo turbinos "exducer" iki ishmetimo vamzdzio diametro.
Kaip supratau, geriausia, kad wastegate'o "kanalas" butu atskiras nuo ishmetamu duju srauto einancio per turbina, kad nebutu itakojama "backpressure".
Jei nedaryt atskiro "ishmetimo" wastegeitui laukan, galima padaryti atskira, bet susijungianti i viena ishmetimo sistema uz 12-18" atstumo nuo turbinos..
"Backpressure" dideja ir nuo to, kad kyla temperatura (aishku ir duju turis) einant srautui per katalizatoriu del "exothermic oxidation of unburned hydrocarbons" ..

Beja, kas yra "cylinder scavenging" ?

[spade]

p.s. gal dar tokiu kanku?:)

Imesiu toki konceptualu... "Your place in the sh*tladder"

[Torva]

labai teisinga info... thanx

As for primary lengths on turbo headers, it is advantageous to use
equal-length primaries to time the arrival of the pulses at the turbine
equally and to keep cylinder reversion balanced across all cylinders. This
will improve boost response and the engine's VE. Equal-length is often
difficult to achieve due to tight packaging, fabrication difficulty, and the
desire to have runners of the shortest possible length."

jei atmintis manes neapgauna for n/a engines headeriai rekomenduojami kuo ilgesni?

[Torva]

Kaip supratau, geriausia, kad wastegate'o "kanalas" butu atskiras nuo ishmetamu duju srauto einancio per turbina

jo i geriausiai jo niekur nejungti

Jei nedaryt atskiro "ishmetimo" wastegeitui laukan, galima padaryti atskira, bet susijungianti i viena ishmetimo sistema uz 12-18" atstumo nuo turbinos..

bet cia juk irgi atskiras isvedimas wgate'ui.. ane
siaip antrasis variantas butu deti separatoriu tarp wgate'o ir pagrindinio ismenatu duju srauto, o vamzdi naudoti ta pati. siaip mazdistai downpipe'us ir tokius ir tokius daro. boost creepo atzvilgiu padeda ir tas ir tas

[Conan]

p.s. gal dar tokiu kanku?:)

Prasom...

"...

There is too much misinformation regarding exhaust theory. What kind of misinformation? For starters, there are a lot of people in the "Bigger is Better" camp. We're talking about exhaust pipe diameters. Even the big magazine editors are boldly smattering statements like, "For a turbo car, you can't get an exhaust pipe that's too big." Also, terms like "back pressure" and the statement, "An engine needs back pressure to run properly!" really can be mis-leading.

Let's start from the beginning. What is an exhaust system? Silly question? Not hardly. Exhaust systems carry out several functions. Among them are: (1) Getting hot, noxious exhaust gasses from your engine to a place away from the engine compartment; (2) Significantly attenuating noise output from the engine; and (3) In the case of modern cars, reduce exhaust emissions.

Hardware

In order to give you a really good idea of what makes up an exhaust system, let's start with what exhaust gas travels through to get out of your car, as well as some terms and definitions:

After your air/fuel mixture (or nitrous/fuel mixture) burns, you will obviously have some leftovers consisting of a few unburned hydrocarbons (fuel), carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, phosphorus, and the occasional molecule of a heavy metal, such as lead or molybdenum. These are all in gaseous form, and will be under a lot of pressure as the piston rushes them out of the cylinder and into the exhaust manifold or header. They will also be hotter 'n Hades. (After all, this was the explosion of an air/fuel mixture, right?) An exhaust manifold is usually made of cast iron, and its' primary purpose is to funnel several exhaust ports into one, so you don't need four exhaust pipes sticking out the back of your Civic.

Exhaust manifolds are usually pretty restrictive to the flow of exhaust gas, and thus waste a lot of power because your pistons have to push on the exhaust gasses pretty hard to get them out. So why does virtually every new automobile sold have exhaust manifolds? Because they are cheap to produce, and easy to install. Real cheap. Real easy.

"Ok," you ask, "so now what?" Ah, good thing you asked. The performance alternative to the exhaust manifold is a header. What's the difference? Where a manifold usually has several holes converging into a common chamber to route all your gasses, a header has precisely formed tubes that curve gently to join your exhaust ports to your exhaust pipe. How does this help? First of all, as with any fluid, exhaust gasses must be treated gently for maximum horsepower production. You don't want to just slam-bang exhaust gas from your engine into the exhaust system. No way, Jo-se'! Just as the body of your '94 Eclipse is beautiful, swoopy, and aerodynamic, so must be the inside of your exhaust system.

Secondly, a header can be "tuned" to slightly alter your engines' characteristics. We'll go in-depth into header tuning a little later.

Nextly, exhaust gasses exit from your manifold or header, travel through a bit of pipe, then end up in the catalytic converter, or "cat". The cat's main job is to help clean up some of the harmful chemicals from your exhaust gas so they don't end up in your lungs. In most cars, they also do a great job of quieting things down and giving any exhaust system a deeper, mellow tone. You'll see a lot of Self-Proclaimed Master Technicians (SPMT's) telling people that removing a cat will get you tons of power. There's room for debate on this, but in our experience, removing a catalytic converter from a new car won't gain you much in the horsepower department. If you drive an OBD-II equipped car, you'll also get that damn annoying CHECK ENGINE light burnin' up your dashboard. (And for all you racers concerned with OBD-II's fabled "limp mode", you can put your fears to rest.)

From the catalytic converter, the exhaust gasses go through a bit more pipe and then into a muffler, or system consisting of several mufflers and/or resonators.

Are you a muff?

Exhaust gases leave the engine under extremely high pressure. If we allowed exhaust gasses escape to the atmosphere directly from the exhaust port, you can well imagine how loud and cop-attracting the noise would be. For the same reason gunshots are loud, engine exhaust is loud. Sure, it might be cool to drive around on the street with that testosterone producing, chest-thumping, 150 decibel roar coming from your car… for about 5.3 seconds. (Not 5.2 or 5.4 seconds… 5.3.) Even the gentleman's gentleman has gotta use a muffler, or system of mufflers, on their exhaust.

Again, you may hear a few SPMT's tell you that "Borla mufflers make horsepower!" Or "An engine needs some backpressure to run properly!" Nonsense. A muffler can no more "make" horsepower than Wile E. Coyote can catch roadrunners. Any technician with any dyno experience will tell you that the best mufflers are no mufflers at all!

Types of Muff

Mufflers can take care of the silencing chores by three major methods: Absorption, Restriction, and Reflection. Mufflers can use one method, or all three, to attenuate sound that is not so pleasing to the ears of the Highway Patrol.

The absorption method is probably the least effective at quelling engine roar, but the benefit is that "absorbers" are also best at letting exhaust gas through. Good examples of absorbers are the mufflers found in GReddy BL-series exhausts, DynoMax UltraFlow, and the good old-fashioned Cherry Bomb glasspack.

Absorption mufflers are also the simplest. All of the above named mufflers utilize a simple construction consisting of a perforated tube that goes through a can filled with a packing material, such as fiberglass or steel wool. This is similar to simply punching holes in your exhaust pipe, then wrapping it up with insulation. Neat, huh?

Another trick absorption mufflers use to kill off noise is, well, tricky. For example, the Hooker Aero Chamber muffler is a straight-through design, with a catch. Instead of a simple, perforated tube, there is a chamber inside the muffler that is much larger than the rest of the exhaust pipe. This design abates sound more efficiently than your standard straight-through because when the exhaust gasses enter this large chamber they slow down dramatically. This gives them more time to dwell in the sound insulation, and thus absorb more noise. The large chamber gently tapers back into the smaller size of your exhaust pipe, and the exhaust gasses are sent on their merry way to the tailpipe.

Restriction

Doesn't that word just make your skin crawl? It's right up there in the same league with words like "maim".

Obviously, a restrictive muffler doesn't require much engineering expertise, and is almost always the least expensive to manufacture. Thus, we find restrictive mufflers on almost all OEM exhaust systems. We won't waste much time on the restrictive muffler except to say that if you got 'em, you might not want to flaunt 'em.

Reflection

Probably the most sophisticated type of muffler is the reflector. They often utilize absorption principles in conjunction with reflection to make the ultimate high-performance silencer. Remember any of your junior high school math? Specifically, that like numbers cancel each other when on a criss-cross? That's the same principal used by the reflective muffler. Sound is a wave. And when two like waves collide, they will "cancel" each other and leave nothing to call a corpse but a spot of low-grade heat.

There are numerous engineering tricks used in the reflective muffler. Hedman Hedders makes a muffler that looks a lot like a glasspack. In fact, it is a glasspack with a catch. The outer casing is sized just-so, so that high-pitched engine sound (what we deem "noise") is reflected back into the core of the muffler… where those sound waves meet their maker as they slam right into a torrent of more sound waves of like wavelength coming straight from the engine. And, this muffler is packed with a lot of fiberglass to help absorb any straggling noise that might be lagging behind.

The Exhaust Pulse

To gain a more complete understanding of how mufflers and headers do their job, we must be familiar with the dynamics of the exhaust pulse itself. Exhaust gas does not come out of the engine in one continuous stream. Since exhaust valves open and close, exhaust gas will flow, then stop, and then flow again as the exhaust valve opens. The more cylinders you have, the closer together these pulses run.

Keep in mind that for a "pulse" to move, the leading edge must be of a higher pressure than the surrounding atmosphere. The "body" of a pulse is very close to ambient pressure, and the tail end of the pulse is lower than ambient. It is so low, in fact, that it is almost a complete vacuum! The pressure differential is what keeps a pulse moving. A good Mr. Wizard experiment to illustrate this is a coffee can with the metal ends cut out and replaced with the plastic lids. Cut a hole in one of the lids, point it toward a lit candle and thump on the other plastic lid. What happens? The candle flame jumps, then blows out! The "jump" is caused by the high-pressure bow of the pulse we just created, and the candle goes out because the trailing portion of the pulse doesn't have enough oxygen-containing air to support combustion. Neat, huh?

Ok, now that we know that exhaust gas is actually a series of pulses, we can use this knowledge to propagate the forward-motion to the tailpipe. How? Ah, more of the engineering tricks we are so fond of come in to play here.

Just as Paula Abdul will tell you that opposites attract, the low pressure tail end of an exhaust pulse will most definitely attract the high-pressure bow of the following pulse, effectively "sucking" it along. This is what's so cool about a header. The runners on a header are specifically tuned to allow our exhaust pulses to "line up" and "suck" each other along! Whoa, bet you didn't know that! This brings up a few more issues, since engines rev at various speeds, the exhaust pulses don't always exactly line up. Thus, the reason for the Try-Y header, a 4-into-1 header, etc. Most Honda headers are tuned to make the most horsepower in high RPM ranges; usually 4,500 to 6,500 RPM. A good 4-into-1 header, such as the ones sold by Gude, are optimal for that high winding horsepower you've always dreamed of. What are exhaust manifolds and stock exhaust systems good for? Besides a really cheap boat anchor? If you think about it, you'll realize that since stock exhausts are so good at restricting that they'll actually ram the exhaust pulses together and actually make pretty darn good low-end torque! Something to keep in mind, though, is that even though an OEM exhaust may make gobs of low-end torque, they are not the most efficient setup overall, since your engine has to work so hard to expel those exhaust gasses. Also, a header does a pretty good job of additionally "sucking" more exhaust from your combustion chamber, so on the next intake stroke there's lots more fresh air to burn. Think of it this way: At 8,000 RPM, your engine is making 280 pulses per second. There's a lot more to be gained by minimizing pumping losses as this busy time than optimizing torque production during the slow season.

General Rules of Thumb with Headers

You will undoubtedly see a variety of headers at your local speed shop. While you won't be able to determine the optimal power range of the headers by eyeballing them, you'll find that in general, the best high-revving horsepower can be had with headers utilizing larger diameter, shorter primary tubes. Headers with smaller, longer primaries will get you slightly better fuel economy and better street driveability. With four cylinder engines, these are also usually of the Tri-Y design, such as the DC Sports and Lightspeed headers.

Do Mufflers "Make" Horsepower?

The answer, simply, is no. The most efficient mufflers can only employ the same scavenging effect as a header, to help slightly overcome the loss of efficiency introduced into the system as back pressure. "So," you ask, "what the is the best flowing muffler I can buy?"

According to the flowbench, two of the best flowing units you can buy are the Walker Dyno Max and the Cyclone Sonic. They even slightly out flow the straight through designs from HKS and GReddy BL series. Amongst the worst, are the Thrush Turbo and Flow Master mufflers.

Resonators

On your typical cat-back exhaust system, you'll see a couple of bulges in the piping that are apparently mini-mufflers out to help the big muffler that hangs out back. These are called Helmholtz Resonators and are very similar to glasspacks. The main difference is that firstly, there is no sound-absorbing fiberglass or steel wool in a Resonator. And secondly, their main method of silencing is the reflective principle, not absorption. An easy way to tell the difference between a glasspack and a true Helmholtz Resonator is to "ping" one with your finger. A glasspack will make a dull thud, and a true Resonator will make a clear "ping!" sound.

Turbos

Another object that might be sitting in your exhaust flow is a turbine from a turbocharger. If that is the case, we envy you.

Not only that, but turbos introduce a bit of backpressure to your exhaust system, thus making it a bit quieter. All of the typical scavenging rules still apply, but with a twist. Mufflers work really well now! Remember, one of the silencing methods is restriction, and a turbine is just that, a restriction.

This is actually where the term "turbo muffler" is coined. Since a turbine does a pretty good job of silencing, OEM turbo mufflers can do a lot less restricting to quiet things down. Of course, aftermarket manufacturers took advantage of this performance image and branded a lot of their products with the "turbo" name in order to drum up more business from the high performance crowd. We're sad to say that the term "turbo" has been bastardized in this respect, and would like that to serve as a warning. A "turbo" muffler is not necessarily a high-performance muffler.

Pipe Sizing

We've seen quiet a few "experienced" racers tell people that a bigger exhaust is a better exhaust. Hahaha… NOT.

As discussed earlier, exhaust gas is hot. And we'd like to keep it hot throughout the exhaust system. Why? The answer is simple. Cold air is dense air, and dense air is heavy air. We don't want our engine to be pushing a heavy mass of exhaust gas out of the tailpipe. An extremely large exhaust pipe will cause a slow exhaust flow, which will in turn give the gas plenty of time to cool off en route. Overlarge piping will also allow our exhaust pulses to achieve a higher level of entropy, which will take all of our header tuning and throw it out the window, as pulses will not have the same tendency to line up as they would in a smaller pipe. Coating the entire exhaust system with an insulative material, such as header wrap or a ceramic thermal barrier coating reduces this effect somewhat, but unless you have lots of cash burning a hole in your pocket, is probably not worth the expense on a street driven car.

Unfortunately, we know of no accurate way to calculate optimal exhaust pipe diameter. This is mainly due to the random nature of an exhaust system -- things like bends or kinks in the piping, temperature fluctuations, differences in muffler design, and the lot, make selecting a pipe diameter little more than a guessing game. For engines making 250 to 350 horsepower, the generally accepted pipe diameter is 3 to 3 ½ inches. Over that amount, you'd be best off going to 4 inches. If you have an engine making over 400 to 500 horsepower, you'd better be happy capping off the fun with a 4 inch exhaust. Ah, the drawbacks of horsepower. The best alternative here would probably be to just run open exhaust!

Other Rules

A lot of the time, you'll hear someone talking about how much hotter the exhaust system on a turbo car gets than a naturally aspirated car. Well, if you are catching my drift so far, you'll know that this is a bunch of BS. The temperature of exhaust gas is controlled by air/fuel mixture, spark, and cam timing. Not the turbo hanging off the exhaust manifold.

When designing an exhaust system, turbocharged engines follow the same rules as naturally aspirated engines. About the only difference is that the turbo engine will require quite a bit less silencing.

Another thing to keep in mind is that, even though it would be really super cool to get a 4 inch, mandrel bent exhaust system installed under your car, keep in mind that all of that beautiful art work won't do you a bit of good if the piping is so big that it gets punctured as you drag it over a speed bump! A good example of this is the 3 inch, cat back system sold by Thermal Research and Development for the Talon/Laser/Eclipse cars. The piping is too big to follow the stock routing exactly, and instead of going up over the rear suspension control arms, it hangs down below the mechanicals, right there in reach of large rocks! So when designing your Ultimate Exhaust System, do be careful!

Original article courtesy of OverBoost.com, some changes made.

..."

[spade]

Pastarasis textas labiau link atmosferiniu varikliu (nors ir ish overboost'o)...

jei atmintis manes neapgauna for n/a engines headeriai rekomenduojami kuo ilgesni?

For all practical purposes...
Siaip tai zhinoma taip nera - bet realioj mashinoj praktishkai neimanoma juos padaryti per ilgus...

[Guest]

calibroj maciau trecia Y sujungta vos ne ties vairuotojo sikna. Nerzinis, ryskiai ceche darytas. O pirmi du uz variklio jau sujungti. sochinej, ten kelnes per prieki iseina...

[r7kyc82k]

ziurau rimti bazarai vartomi .



gal kas jau visus tuos tekstus yra i lt arba rus isvertes?

[Minde_Kei]

ziurau rimti bazarai vartomi .

gal kas jau visus tuos tekstus yra i lt arba rus isvertes?

sveikas prisijunges beje perskaityk taisykles (vistiek spade'as pasakytu)

[r7kyc82k]

ziurau rimti bazarai vartomi .

gal kas jau visus tuos tekstus yra i lt arba rus isvertes?

sveikas prisijunges beje perskaityk taisykles (vistiek spade'as pasakytu)

jos kazkuom skiriasi nuo bendru ir kitu forumu taisykliu?
sejp visas mintinai zinau, nes pats dali ir kuriau motomanuose
ok einu pazet :D

[Sheikhas]

OT: Ziuriu tuoj ir sitam forume susirinks ta pati chebra, kaip ir ....kitur .
Ir nebeliks jokios ivairoves

[ebola]

nori padaryti dabar toki normalesni foruma, reik daryt mokama. Beje, cia bazaras apie ismetimo sistemas.Yra toks saitas headerdesign.com, ten tik reikia uzsiregistruoti, ir tau duoda pora tokiu paprastu, bet mano supratimu visai protingu programeliu headeriam pasiskaiciuoti. Ir siaip yra idomios info.Problema biski kad ten viskas amerikenu v8 yra sukurta, bet kas turi vingi kita, prisitaikys ir mazam varikliui. Ir coliai, aisku. Yra tokia http://www.joshmadison.com/software ir jis turi tokia miniprograma "convert". Rekomenduociau visiem, labai naudinga kai listalini interneta...ir neaisku kiek yra 0.041 colio pavyzdziui, ar kokia yra 300cfm oro mase...