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remote mount turbos

T

TRicker

Hard-core CEG'er
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Jun 25, 2006
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wtf is up with these things. i see them a lot lately in magazines, from STS and such. looks like it works. twin turbos, one at the rear of each end of the exhaust. but what about the boost characteristics.... wouldnt it take forever to make boost through 15ft of piping? and how do you oil this thing... there's no way that they can run oil all the way to those things through the engine, you would have to put like 12 quarts in the car to fill the lines!

wtf is this deal? someone enlighten me.

i also saw a remote mount turbo SHO that made like 300WHP on a junkyard setup. ran 14.1's too.
 
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Turbo's don't use that much oil. The line is under pressure and fairly small for the supply. You do need a little sump to collect the oil coming out of the turbo and a pump to send it back to the engine though.
 
yes, rear turbos have been proven and work great! they have there advantages over a normal setup. if the piping and turbos are sized right then lag is all but eliminated as good as any setup. it keeps the heat out of the engine bay. they sometimes require no intercooler because of the long run on the cold side acts as the intercooler. the oil return setup being pumped back is actually nice because you can introduce it back into the engine other places besides the pan, i have even seen it plumbed into the oil fill neck. they have an alarm system that lets you know if the pump has failed and some have it shut the motor down.
 
A remote turbo "might" be a way for us Californians to "beat the system" if the plumbing in the engine compartment was hidden well enough. I can't remember how thoroughly the smog guy looked under the car the last time my car was tested. Hmm. :cool:
 
TRicker said:
wouldnt it take forever to make boost through 15ft of piping? and how do you oil this thing... there's no way that they can run oil all the way to those things through the engine, you would have to put like 12 quarts in the car to fill the lines!
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the time figure is something along the lines of 0.05 Seconds for an air molecule to get from the compressor to the intake; when you look at turbo kits for many vehicles (especially ones with FMIC's) there is easily 6-10 feet of cold-side tubing plus the slight restriction of an air-charge cooler.

Although the lines do call for a greater volume of additional oil over a conventional turbo system, the ~1 quart is substantially less than the 2-4 quarts that would be required to build a stand alone oiling system capable of being cooled properly.

The big draw back to remote mounts kits is that the exhaust has cooled substantially by the time it reaches the turbine and has lost much of the energy required to spool the turbo. As a substitute for the lost energy, remote mounts run smaller housings and rely on increased levels of back-pressure in the exhaust.
 
i havent seen any proof that sts is less efficent than conventional setups....check shoforums.com iirc there's a member or two running rear mounts
 
95pgt-t said:
i havent seen any proof that sts is less efficent than conventional setups....check shoforums.com iirc there's a member or two running rear mounts
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physics says that a rear mount system is less efficient. The turbine of a turbocharger operates on the heat energy exhausted by the engine, in a rear mount system, exhaust gases cool loosing energy while traveling through the exhaust pipes. Rear mount systems, like the STS, make use of reductions in turbine housing size which increase exhaust pressures, thereby increasing temperatures (since thermodynamics tell us that the compression of a gas result in increases in temperature). The decrease in turbine housing size also constitutes an increase in exhaust restriction, reducing the volumetric efficiency of the driving engine.

Rear mount systems are not as efficient as their conventional brethren; precisely how less efficient depends on numerous variables, but if you take two identical engines and two identical turbos, mount them so that one is rear-mount and one conventional mount, the conventional mount engine will result in greater returns.
 
95pgt-t said:
i havent seen any proof that sts is less efficent than conventional setups....check shoforums.com iirc there's a member or two running rear mounts
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What do you mean by "proof." Its just thermodynamics.

The question should really be "how much less efficient?" The system can be designed to work with a less energetic (cooler) exhaust flow. Always tradeoffs to consider.
 
JEDsContour said:
What do you mean by "proof." Its just thermodynamics.

The question should really be "how much less efficient?" The system can be designed to work with a less energetic (cooler) exhaust flow. Always tradeoffs to consider.
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Apparantly some of you didnt read the other thread regarding the rear mount turbos.

STS uses SMALLER diamter exhaust piping as well as they jet-hot coat it. the smaller piping along with the coating are more than enough to make up for whatever thermal losses would have been acrued from the length of the pipe. the smaller piping also helps keep the velocity of the gases up as well.

The rear mounted turbos, when sized properly, really do work just as well as a conventional setup. the only real downside to it is the plumbing, both intercooler and oil. air filters can be located in the trunk to keep them from getting wet so thats not an issue. i have even seen people build a box like structure under the turbo to keep them from gettingwet or hit with road debris.
 
I don't think that anyone is taking the position that rear-mount does not work, only that the benefits in terms of ease of packaging, may not be worth the added complexities in the oiling system or the diminished returns.

Decreased exhaust diameter might help keep velocity up, but it also acts as a greater restriction on the engine, increasing back-pressure, which decreases exhaust scavenging and cylinder filling, thereby decreasing effective volumetric efficiency. A lower VE results in less power.

Fully-optimized rear mount setups do work, and they do offer the benefit of contributing to better weight distribution, but comparably built standard mounts and rear mounts will always favor the standard mount based purely on the required physics.

That being said there is a professional mustang drag racer that should be running rear mount next season and it will be interesting to see how the weight distribution benefits work to outweigh any potential power losses associated with the rear mount.
 
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striker2 said:
Apparantly some of you didnt read the other thread regarding the rear mount turbos.

STS uses SMALLER diamter exhaust piping as well as they jet-hot coat it. the smaller piping along with the coating are more than enough to make up for whatever thermal losses would have been acrued from the length of the pipe. the smaller piping also helps keep the velocity of the gases up as well.

The rear mounted turbos, when sized properly, really do work just as well as a conventional setup. the only real downside to it is the plumbing, both intercooler and oil. air filters can be located in the trunk to keep them from getting wet so thats not an issue. i have even seen people build a box like structure under the turbo to keep them from gettingwet or hit with road debris.
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Efficiency has a specific meaning when used in an engineering sense.
 
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JEDsContour said:
Efficiency has a specific meaning when used in an engineering sense.
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if its a twin turbo setup on a V style engine you will want true duals, one to each turbo. 2"/2.25" piping is plenty large enough for most V6's as well as some of the smaller V8s. for the larger engines i believe they step up to 2.25"/2.5" piping. look at Steeda's true duals for the SVT, 2" piping and he gained several horses from it.


as i said before they size the turbo to work from the back of the car.

STSturbo.com said:
With the turbo so far back, don't you get a lot of turbo lag?
No, our turbochargers are sized to operate at this remote location. Just like any turbocharger, once the turbo is up to temperature and in the rpm range for which it was designed to operate. The boost comes on hard and fast. All of our systems will produce full boost below 3000 rpm.
If you were to take a conventional turbo and place it at the rear, you would have lots of lag and consequently, our turbo wouldn't work properly if mounted up front.
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CSVTturbo said:
Who doesnt want RAYS setup. He probably has the best running turbo contour out there.:laugh: :laugh:
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i havent seen a "bad running" turbo contour out there from what i saw at SZ. i just like the looks of his setup. nicely tucked in everywhere. burrita's is nice too. but i like the water/air intercooler setups too.
 
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