85

:::::VIDEO:::::
http://youtube.com/watch?v=2B2mwgsvikY
thanks for the replys, heres a youtube video of a instal/dyno and street run on a Twin turbo Vet

here is another VIDEO, seems like most of the videos out there are of vets. Not my choice in cars but this one makes 740whp so any kit that can produce 740 in my book is a worthy competitor even if its on a V8

http://youtube.com/watch?v=B_tTTihJfP0


I remember seeing these videos a wail back of a turbo kit where the turbo was back where the muffler normally is. The kits were over prices but I remember the videos being kinda cool. Anyone know who makes them?

on top of that, Anyone know how the setup worked out? bad lag/response?


Modified by hks85 at 10:05 AM 1/10/2007


Modified by hks85 at 1:11 PM 1/10/2007

urbansi

Search for STS.

According to people that i have spoken with they are lag free for the most part...but i refuse to believe that

Joseph Davis

They are lag free, why does that surprise you? Turbos spin based on flow - you get exactly as much airmass at the rear axle as you do at the manifold, just modify the housing to reflect temp/density changes. The STS cars run .63 AR stage 3 T3/T04E, whoopty.

The guys who upgrade to T67 or similar/larger turbos have boost spike problems. Last STS-based T67 Camaro I saw @ Carolina Automasters couldn't boost less than 15 psi... I didn't see a problem with it, but th owner was being a woman about it.

0morgan@synapse motorsport

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Joseph Davis &raquo;</TD></TR><TR><TD CLASS="quote">They are lag free, why does that surprise you? Turbos spin based on flow - you get exactly as much airmass at the rear axle as you do at the manifold, just modify the housing to reflect temp/density changes. The STS cars run .63 AR stage 3 T3/T04E, whoopty.

The guys who upgrade to T67 or similar/larger turbos have boost spike problems. Last STS-based T67 Camaro I saw @ Carolina Automasters couldn't boost less than 15 psi... I didn't see a problem with it, but th owner was being a woman about it.</TD></TR></TABLE>

well lets see, the turbo in the rear has to fill a much larger amount of charge piping. it takes time to pressurize charge piping. hence more lag. it takes time for exhaust gases to get from the engine to the turbo and loses heat, and velocity so it takes more gases to spool the turbo.

nvmeplz

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">

well lets see, the turbo in the rear has to fill a much larger amount of charge piping. it takes time to pressurize charge piping. hence more lag. it takes time for exhaust gases to get from the engine to the turbo and loses heat, and velocity so it takes more gases to spool the turbo.</TD></TR></TABLE>

No they are pretty much lag free. They are very responsive. I agree with the poster above you.

GimpyAccord

Rode in an LT1 Mullet with an STS kid, didn't seem laggy to me

Long as the turbo is sized appropriatly it should be alright...

DaveF

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nvmeplz &raquo;</TD></TR><TR><TD CLASS="quote">

No they are pretty much lag free. They are very responsive. I agree with the poster above you. </TD></TR></TABLE>

i would hate to be the guy disagrein with him

rmcdaniels

Well let's see, a medium-frame turbo can push 30 lbs/min of air, or more than 200 CFM @ 15 PSI, figure an extra 6-8 feet of charge pipe to get it from the back of the car, so that's about an extra 2.8 cu/ft of charge pipe it has to fill, so roughly .014 seconds of lag for the extra charge pipe. As for loss of velocity based on less volume from cooling exhaust gases, without doing the math I'd guess that it's also insignificant, and probably compensated for by the increased density of the gases that reach the turbine. The only thing I'd be concerned about is the oiling, but I think they have a way to deal with that.

0morgan@synapse motorsport

u guys cant seriously think that a rear mounted turbo will have no ill effect, and not suffer from more lag than a manifold mounted turbo.

so far u guys have compared relatively small turbos, a t04e and a 67mm on a 5.7 liter is tiny. of course its going to feel like its not much lag. try putting something big on it, im not saying the lag is terrible. but u cannot deny that it will have more lag than a manifold mounted turbo.

not to mention pulses, look how much of a difference a divided housing makes from a regular manifold. figure that would play a role as well.

GimpyAccord

Oh I'm sure it has some ill effect, I don't think anyone is denying that.

Most people who'd be interested in a configuration like that are most likely not concerned by those issues.

Far as the oiling, yah... my only major concern would be that return pump crapping out. They seem to be pretty darn reliable though, a lot of those guys with the STS kits on trucks have been out there awhile now.

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">it takes time for exhaust gases to get from the engine to the turbo and loses heat, and velocity so it takes more gases to spool the turbo.</TD></TR></TABLE>

All of which is largely irrelevant, since rate of displaced airmass is constant. What I am saying is that a hotter, less dense gas at a higher velocity carries the exact same energy as a colder, denser gas at a lower velocity. What you are insinuating is that the temperature of the exhaust matters - I suggest you try to spool a turbo by sticking it in your oven, and then try to spool it with some chilly compressed air.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">u guys cant seriously think that a rear mounted turbo will have no ill effect, and not suffer from more lag than a manifold mounted turbo.</TD></TR></TABLE>

You'll have to be specific about ill effects, I'm not a mind reader.

As far as lag, size the hot side of the turbo to reflect the denser smaller-volume-but-equal-energy exhaust flow. The exhaust charge changes volume, so should your turbine. Pretty basic physics.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">try putting something big on it, im not saying the lag is terrible. but u cannot deny that it will have more lag than a manifold mounted turbo.</TD></TR></TABLE>

I deny it. I also deny your ability to factually refute it.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dturbocivic &raquo;</TD></TR><TR><TD CLASS="quote">i would hate to be the guy disagrein with him </TD></TR></TABLE>

Yeah, but you so love sitting there with a bowl of popcorn and large cherry coke, watching the carnage.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GimpyAccord &raquo;</TD></TR><TR><TD CLASS="quote">Far as the oiling, yah... my only major concern would be that return pump crapping out. They seem to be pretty darn reliable though, a lot of those guys with the STS kits on trucks have been out there awhile now.</TD></TR></TABLE>

Most of the new electric power steering pumps are a lot lighter and more petite than the stuff on Subaru XT6's and older NSXs, and the OEM is nothing if not hugely **** retentive about making sure power steering failures don't occur often.

I'm running an EPS pump from an EP3 in a rear mounted setup on a CRX Si. Turbo drains into a sump that holds a couple quarts, the EPS pump feeding an IHI. Long story short, I got sick of some of the local autocross homos running their mouths, and since I lack appreciable driving talent I intend to cheat - Smoky Yunick would be proud of me. Pass side frame rail acts as a piece of charge pipe, feeds into the bottom of the factory airbox, stock intake arm and connections are sealed up with a little RTV. I figure all I need is 5 psi and 130 whp to expletive some people up in a stock class, and it'll pass a teardown if they don't go poking at the airbox.

Tuesday Club

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Joseph Davis &raquo;</TD></TR><TR><TD CLASS="quote">
. Pass side frame rail acts as a piece of charge pipe, feeds into the bottom of the factory airbox, stock intake arm and connections are sealed up with a little RTV. I figure all I need is 5 psi and 130 whp to expletive some people up in a stock class, and it'll pass a teardown if they don't go poking at the airbox. </TD></TR></TABLE>


shame shame shame

DJ_SaNdOz

I enjoy reading your intelligent arguments and your matter of fact and slightly snippy criticisms

I have considered a rear mounted setup, it seems like a great idea with little to no downside. The only issue that I see, if you can even call it an issue, would be the accessibility of the turbo.

0morgan@synapse motorsport

the exhaust gases transfer heat through the metal in the exhaust system. so now the metal is hot and the air around it has become hot as well.

heat=energy so it has transferred energy into the metal and air around it.

so how does it have the same energy at the beginning as it does at the end it doesnt.

jinxmrp

personally I think it is way more accessible than a front mounted turbo on 90% of cars. Hondas are one of the cars that are easier to get to but seems easier than a ramhorn, and no I/C needed.

GimpyAccord

"Smoky Yunick would be proud"

---

HE sure would, I'd reccomend any of you guys read his books... that guy knew how to "bend" the rules

DJ_SaNdOz

An I/C is probably still a good idea on higher boost setups I would think.

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">the exhaust gases transfer heat through the metal in the exhaust system. so now the metal is hot and the air around it has become hot as well. </TD></TR></TABLE>

I have a visual analogy for you. The energy in the cooled exhaust charge at the rear-mounted turbo is an elephant. The amount of energy that soaks into the exhaust pipe is a housecat. The amount of energy that the exhaust pipe can radiate is a blind mole. The housecat is so busy stalking the mole that it doesn't see the elephant stepping on both it and the mole. The elephant obviously didn't notice either of them because elephants are fastidious animals who dislike getting strawberry jam between their toes.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">heat=energy so it has transferred energy into the metal and air around it.

so how does it have the same energy at the beginning as it does at the end it doesnt.</TD></TR></TABLE>

No, you didn't listen to me at all. The "heat" you speak of is a residual byproduct, it is far and away NOT the bulk of the energy in the exhaust. The bulk of the exhaust's energy is kinetic in nature. If heat were so goddamn speshul, we'd be removing factory CAIs (installed for thermal safety reasons), installing heat exchangers off old air cooled VWs, and sucking hot air radiated from the exhaust manifold.

Look, someone somewhere taught you a bunch of volumetric efficiency bullshit, shoved Ideal Gas LIE down your throat in an attempt to sell you a good-flowing product for a turbocharger system whose only limitation is what it's compressor is rated for. I call this "hp-per-psi LIES," it is marketing tactics to sell Brand Name Products, and in no way shape or form reflects a balanced picture of what is going on underhood. All that matters is airmass. Not massless charged particles such as photons radiating heat - does your turbo spool when you shine a flashlight on it? Not convection - the movement heat by currents - as the current is flowing toward the *** end of the car. Because, those are the two methods by which heat is transferred. No, what matters here is mass. Actual, measurable, palpable mass, possessing of velocity and momentum and therefore kinetic energy which has the ability to physically spin turbines and stuff.

Here, in my best Samuel L Jackson voice: Physics, ************, do you speak it?

0morgan@synapse motorsport

first off your wrong heat is transfered in 3 different ways, convection, radiation, and conduction. of course u ignored the one relating to our example.

your examples dont make any sense, it would be like defending my side and saying put the turbo in a freezer with that oh so dense air and see if it spools. also, why are u trying to compare the tempurature of the air needed during combustion and the tempurature of the air needed to drive a turbo, to completely different actions.

fact is heat = energy and the energy lost before the turbo is more in a rear mounted turbo. im not saying how little or large that amount may be.

fact is hot gases move faster than cold gases, and when it comes down to it that velocity drives the turbo a lot more than the increased pressure of a denser colder air. why is this because of momentum. u are taking an exact mass and reducing its speed. therefore u have less momentum. matter with less momentum can transfer less momentum aka push a turbo.

u cant win this argument because physics are on my side. heres the fault in your logic. mass cant do jack squat without energy. u think because it has the same mass it has the same energy.

energy cannot be created or destroyed it can only change forms.&lt;--this is something we all learn in high school, well i guess if u went, its not something we learn from a turbo manufacturer. heat is energy. heat transferred from the exhaust gases through the exhaust piping and is now heating the air around it. how does the exhaust gases on the rear mount have the same exact energy?

i havent even mentioned the vector(huge variable of the momentum equation) of the exhaust gases is not nearly as focused on a rear mounted turbo. that would probly be the biggest factor in the drawback of this turbo application, as far as exhaust gases are concerned.


Modified by hybrdthry911 at 2:02 AM 1/10/2007

Joseph Davis

Eh, totally spaced it, actually. I'm supposed to be in bed, you know.

I refer you to Vizard's work on knock limit - if it happens fast enough then there is no dwell time for any thermal transfer to happen. You heard Mr McDaniels about how quickly charge pipe gets filled under boost, same principle with the exhaust pipe.


No, your argument is that temperature matters. My argument is that kinetic energy matters, and past the exhaust valve kinetic energy is by and large seperate from heat except when it comes time to calc surface area required for the density at the tailpipe to spool a given turbo.

Apparently I am not the only one up past his bedtime. Try that again, you made zero sense.

I am saying how much that amount of energy is: insignificant. That has been my point all along.

Hot gasses expand. For a given pressure, they occupy a greater volume. Since the volume of an exhaust pipe is pretty fixed, compared to cold gasses they are at a higher pressure and this causes the higher rate of flow. How can you say there is increased pressure with cold, denser air?

The exhaust gas comes to a complete and total standstill, despite inertia, because it caught a little cold? You mean the hot gas isn't pushing against the colder gas, forcing it on?

Wait, I know! You are saying all that pressure is dissipating because exhaust pipe is an incredibly efficient heat exchanger? Boy, do I ever feel stupid for running an IC.


Yeah, I dropped out of highschool when I was 15... to go to UNCA. Nice try, though. Since we are discussing education, may I suggest you seek a remedial course in punctuation and grammar?

I assure you that exhaust fills and passes through the exhaust pipe considerably faster than significant heat can be leached out of it. Ever stick a banana or potato or the like in an exhaust pipe at any point in your misspent youth, and stuck around long enough to see how long the engine ran? You realise idles do not have ignition tuned for peak power, and if 8 hp is generated by an idling Honduh I'm incredible impressed. Now, think of the amount of power and flow, at a much higher temp than compressor charge - I must point out since you are so hung up on heat, that exist at the point of spooling a rear mounted turbo. Got the mental image? Are you holding it firmly in your mind?

I want a length of your magic exhaust pipe that dissipates a significant portion of that exhaust heat. If it works I will donate my IC to charity, post an apology to HT, deferring to you in all things, and go start a career in gay ****.


Really? I deal with vector - or more to the point phasor - math on a daily basis. Last I looked under an STS equipped car the exhaust pointed di-rectally into the goddamn turbine inlet. It doesn't get any more focussed than that.


Can I get a hit off your crackpipe?

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">

fact is hot gases move faster than cold gases, and when it comes down to it that velocity drives the turbo a lot more than the increased pressure of a denser colder air. why is this because of momentum. u are taking an exact mass and reducing its speed. therefore u have less momentum. matter with less momentum can transfer less momentum aka push a turbo.

Modified by hybrdthry911 at 2:02 AM 1/10/2007</TD></TR></TABLE>


But the mass isn't constant in time per unit volume. The cooler gas is more dense, therefore has greater momentum at lower speed (p=mv), giving you the same energy density per unit volume (i.e. - pressure). A turbine is driven by fluid pressure and velocity of a mass, so more mass would make up for slightly less velocity.

nowtype

I'll jump in on this later, but one point to make, air becomes more viscous as it heats up. There is a temperature at which air flows best. You want to target that. So the heat is not only PE but directly effects the KE which J. Davis is harping on.

0morgan@synapse motorsport

law of physics, it is impossible to stop heat transfer u can only slow it down. u stand corrected and so does vizard there.

my argument is that momentum matters. in both speed and vector(combine to equal velocity), u have reduced the effectiveness of a turbocharger. heat is the transfer of energy from the kinetic energy of the exhaust gases. if heat is produced then the gases cannot have equal kinetic energy. u again stand corrected.

your point all along is that the exhaust gases have the same energy and you are wrong. you didnt say insignificant u said they were the EXACT same. u stand corrected.

u contradicted yourself.

why go to that extreme, maybe if u have a strong argument u wouldnt have to. noone here said it comes to a total standstill. the colder gases are less effective.

well yes metal is a great heat exchanger. hence your intercooler being made of metal. and again noone here said it was more effective than an intercooler. but it is undenyable there is heat loss. and it is more than significant. whos talking pressure here were talking about momentum. the speed of the exhaust is disipating.

cant even comment on that babble.

if the heat transfer was so insignificant then why is my exhaust much hotter at the exit of the engine than towards the rear of my exhaust.

dont try to compare some more bull that doesnt have to do with this problem, such as your "phasor's" that u do at work. that is a completly different kind of vector.

it doesnt get anymore focused than that....hmm. why does a divided housing manifold flow better than a non divided, pulses and a more direct flow on the exhaust wheel help. now if you have a system that "doesn't get any more focused than that" why dont more incorporate this into their design. lets talk about vector, the exhaust gases post manifold, are much more chaotic in nature, therefore it reduces the efficiency of spooling that turbo.


you are wrong density doesnt have any effect on momentum. its purely mass and velocity.

so a rear mounted turbo now has more mass in its exhaust than a manifold mounted turbo? if u had this "mass" in a manifold driven turbo it would have the same effect. so u cant magically add mass to the rear mounted turbo.

0morgan@synapse motorsport

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nowtype &raquo;</TD></TR><TR><TD CLASS="quote">I'll jump in on this later, but one point to make, air becomes more viscous as it heats up. There is a temperature at which air flows best. You want to target that. So the heat is not only PE but directly effects the KE which J. Davis is harping on. </TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Joseph Davis &raquo;</TD></TR><TR><TD CLASS="quote">
All of which is largely irrelevant, since rate of displaced airmass is constant. What I am saying is that a hotter, less dense gas at a higher velocity carries the exact same energy as a colder, denser gas at a lower velocity. What you are insinuating is that the temperature of the exhaust matters - I suggest you try to spool a turbo by sticking it in your oven, and then try to spool it with some chilly compressed air.
</TD></TR></TABLE>
j davis insinuates that heat doesnt matter

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrdthry911 &raquo;</TD></TR><TR><TD CLASS="quote">
you are wrong density doesnt have any effect on momentum. its purely mass and velocity.

</TD></TR></TABLE>

Not agreeing with you doesn't make me wrong, looking at your grasp of physics, I'm guessing it's the opposite. I don't think that you are taking volume into account, although you seem to be indirectly referencing it to make your point. It seems like your point is that hotter=faster, which is a function of volume, in that hotter means more volume moving through the same space, so more velocity. If you want to make that point, then you've brought volume and density into the discussion, so let's deal with it:

density = mass/volume

momentum = mass*velocity

So less velocity due to less volume (due to lower temperatures) also means greater mass per unit volume, which is density (i.e. - greater velocity can mean less momentum with less mass per unit volume).


As far as viscosity goes, gas viscosity does increase with temperature, but it is linear up to typical automotive EGT's, as is thermal expansion, which would tend to make me think that gains in viscosity would tend to be offset by losses in density, seeing as the turbine is driven by pressure and momentum. While there may be some efficiency gains based on viscosity, stainless steel is actually not very thermally conductive (despite what some may say, it's 8% as conductive as aluminum), and if you put a thermal barrier coating on it (as I do with my exhaust), then heat losses should be relatively insignificant.


I think that there is a misconception that a turbo is a thermal device, it isn't, it's driven by pressure and momentum, that's the definition of an impulse turbine. It responds to force (as change of momentum over time), and if you figure it out based on force, then the temperature/velocity issue is pretty much a wash, with nowtype pointing out that lower gas viscosity hurts efficiency and STS pointing out that lower compressor temps (due to airflow over the whole assembly, cooler oil, etc.) improve it.