Who made that turbo that was NOT IN FRONT of motor?

[twag4]

Also, as Coheed said, the turbo charger selection matters...

[bryan767]

Freed Engineering made this

[hmong337]

Originally Posted by bryan767

Freed Engineering made this

I was debating doing a custom turbo in this location with my local welder but if you take a closer look, that area in the engine bay has a bunch of highly sensitive wires that will get melted.

I still think AVO has the best turbo setup and location. It's too bad the internally wastegated turbo they use is very limited in overall power output.

[stugray]

Originally Posted by twag4

Unlike fluids, air is compressible. The longer charge tube requires a much greater volume of air to be sucked into the turbo, then compressed to fill the volume of the charge tube with compressed air (compressed air is the key here). It is a hugely increased volume required to be compressed. This would definitely add to the delay in full boost achieved at the intake manifold. That is how lag is increased. To understand the difference, blow a mouthful of air through a straw. You can easily feel the flow out of the end of the straw. Then, do the same thing through a garden hose. You likely won't even feel the air flow. In order to feel the air flow, you would have to put a much larger (ie: lungs full of air too, maybe more) volume of air through the garden hose (there are some other things going on here, venturi effect, Bernoulli's principle, but the jist is the same). Just a mouthful won't do it. Much more air has to be moved to yield the results at the other end of the garden hose. Same thing on a rear mounted turbo. Not saying that the turbo won't work, not getting into that argument. But some pretty basic laws of physics are going to apply. There will be a difference. I also won't comment on whether or not a normal, everyday driver would be able to tell a difference. If you hadn't experienced a typical turbo setup, you probably would be happy with this type setup. If you were familiar with the typical setup, then it might be an issue. Seems like a difficult solution to a charge heat problem, when a front mounted intercooler does a good job of cooling- and does not require 18 feet of charge pipe that is susceptible to leaks and damage. Anyway, YMMV. Curious to hear other comments.

So to summarize your statement: "Intercoolers are BAD"

Because if I blow in one end of an intercooler, I cant feel air coming out the other end.

A basic InterCooler rule of thumb is 3-L per 100 hp.
So a Boosted BRZ with 250 hp would need an intercooler of 7.5L.

A pipe 3" in ID, 10 feet long has a volume of 14L so it would have the same effect as a BIG intercooler.

[twag4]

Originally Posted by stugray

So to summarize your statement: "Intercoolers are BAD"

Because if I blow in one end of an intercooler, I cant feel air coming out the other end.

A basic InterCooler rule of thumb is 3-L per 100 hp.
So a Boosted BRZ with 250 hp would need an intercooler of 7.5L.

A pipe 3" in ID, 10 feet long has a volume of 14L so it would have the same effect as a BIG intercooler.

Wow! You clearly understood what I wrote. I didn't make a statement regarding specifics of this setup as I have very little knowledge on any specifics regarding this system. (I do have a chemical engineering degree, and I have some knowledge of fluid dynamics. For the record I am now a pilot for my occupation, and have a great deal of training in aerodynamics as well. So I am not speaking with expertise on automotive application, just the physics of a longer run of compressed gas) Also, longer charge piping wouldn't have the same results as a big intercooler due to the nature of the container/volume. It takes waaaaaaay more energy and time to compress air into a 14l volume -vs- 7.5 l volume given the same rate of compression. Also, using your logic, we could just plumb piping all over the car to cool engine coolant rather than use a radiator. The issue is that the surface area is much less in a pipe than a radiator. The coolant wouldn't be cooled at a quick enough rate. The intercooler works the same way. The volume within the cooler has a much greater surface area, allowing more air molecules to come in contact with the interior surface of the cooler in a shorter period of time- resulting in greater cooling efficiency. I never said a rear turbo wouldn't work. Anyone who has actually dealt with compressing gasses, such as air, knows that the more material you have to use to store the gas results in a greater likelihood that leaks or damage will take place. Try plumbing compressed air all over a shop sometime. The compressor tank doesn't normally leak, it is usually the joints, elbows, valves, etc that drive you crazy and bleed pressure-even though you have greater volume than just the tank. I'm not trying to argue with all of you Internet automotive gurus, just helping the OP understand some of the challenges of such a system. Clearly intelligent design application can overcome such challenges.

[stugray]

Originally Posted by twag4

Wow! You clearly understood what I wrote. .

I DO understand what you wrote (also an Aerospace engineer/EE).

I was just pointing out that when we talk about boosting cars the conventional way, I have NEVER heard someone say:
"WAIT - Dont put on an intercooler because increasing the volume of the intake charge plenum (plumbing) is BAD!"

But the non-engineering types immediately state that this design is bad for that very reason.

Agreed that the heat transfer using a straight pipe wont be as good as an intercooler (and the intake pipe has to run near the exhaust no matter what), but I was just pointing out that having the extra piping is no different than having a huge intercooler (as far as boost lag is concerned).

[kiichiro]

Thanks for all the replies. I'm pretty opinionated.

STS no go

PTUNING FTW it seems

SC's and other Turbo kits are fine for street use

for track, or enthusiasts who insist on not altering the cars balance:
Adding weight behind the rear axle is also a no-go
Adding weight infront of motor is a no go

That takes away alot of kits

Its as important as you want it to be.

I have had two of these cars now, driven turbos, driven e85 tunes, driven SC variants and I'm sure I prefer to keep whatever FI option between the axles if I ever do a 3rd.

At this point short of @ptuning or someone making PTUNING PnP Return-Style Flex Fuel System w/ Racing Fuel Swirl Pot/Surge Tank my 3rd incantation would only be a street build; the biggest problem for me is the fuel loss on left hand 110degree turns. just about everything else this car gave me as a challenge I really enjoyed, but that was a showstopper, for me; just not willing to dive in that deep to find/develop a solution; so I got a 991s for fun and resolved to part with my beloved brz, knowing the only way to get a brz back into the garage would be for DD duty; really to reduce mileage on the german cars that are less disposable and cost more per mile to DD.

Tho, P cars, M3 all give me a perfection of balance that I lost after adding a SC to my BRZ, its not like you dont notice the weight. None of these cars has the fuel starvation that drove me nuts especially at the west track at Firebird, which I frequent and test on etc.

we can spring it 'away' and forget about it, but its there, that SC weight/turbo weight etc; in retrospect I never really did the reserach to see what weighed less, and I bet some turbo setups look like they may have less weight penance, it may be fun to compile a list of Kit weights in a thread?

Its pretty much why I sold my old race build BRZ; I didnt want to keep the car for a variety of other reasons too(engine fire, burnt harnesses, slipping ACT, shedding belts with 2.87 pulley, and mostly road noise I got tired of etc etc), but that aside, the fuel BS on the track was huge for me, and the tunes I ran had a weirdness where with the clutch in, the thing would lightly rev on its own; like the TB wasnt talking to the ECU and there was more fuel, or more air or something. Made speed bumps pretty annoying

As I consider daily driver options, the BRZ is a winner, tho this round I would add a bunch of sound deadening to make it something I enjoyed more off track...

if PTUNING PnP Return-Style Flex Fuel System w/ Racing Fuel Swirl Pot/Surge Tank, it would be a simple gut and rack and cage build, and it would require a FI that was id mounted, its that simple

[hmong337]

Ptuning uses an electric oil scavaging pump.... No thank you.

[kiichiro]

Originally Posted by hmong337

Ptuning uses an electric oil scavaging pump.... No thank you.

Doesn't avo as well? I agree this is a failure waiting to happen at the race track that can get costly if it did ever happen. Short of redundant pumps, is there a Better option? If not it's fine, cause like I said, minus a fuel system fix, tracking is off for this car that talks the talk, but don't walk the walk, in some ways, but the chassis is for sure wonderful in others. Elec pumps are fine for street

[SkAsphalt]

Originally Posted by kiichiro

Doesn't avo as well? I agree this is a failure waiting to happen at the race track that can get costly if it did ever happen. Short of redundant pumps, is there a Better option? If not it's fine, cause like I said, minus a fuel system fix, tracking is off for this car that talks the talk, but don't walk the walk, in some ways, but the chassis is for sure wonderful in others. Elec pumps are fine for street

AVO's oil scavenging pump is mechanical, it is driven by the motor itself (mounts up to where the oil pump would be for the automatic transmission.

[Coheed]

Originally Posted by twag4

Unlike fluids, air is compressible. The longer charge tube requires a much greater volume of air to be sucked into the turbo, then compressed to fill the volume of the charge tube with compressed air (compressed air is the key here). It is a hugely increased volume required to be compressed. This would definitely add to the delay in full boost achieved at the intake manifold. That is how lag is increased.

The length of the charge tube is only one part of the equation here. The charge pipe is only 2" diameter to the intercooler. So here is some simple math.
565ci is the total displacement of 15ft of 2" aluminum piping. You can get the same displacement with a mere 6.5ft of 3" piping. Most kits you see have about 6' of total piping at least. If they are using 3" piping, then the volume increases dramatically over the 2". Even when the 2" pipe is twice as long. The STS kit doesn't have 15' of piping, but this illustrates my point.

Not to mention the fact that turbo lag and intercooler size are related, but it depends on the size of the turbo. Larger turbos fill that volume rather quickly, and the math can tell you that filling a larger intercooler is hardly a large contributor to lag. Especially when the turbos used are 500hp capable.

You could argue that because the STS kit doesn't have mufflers/catalytic converters, or really any exhaust to speak of after the turbo, that the turbo will respond a little better than having the backpressure of an exhaust to push through. This is why you see people run open downpipe.

So a lot of the misconception out there about this kit are just that. Misconception. These guys have been making kits for like 15 years. Seems like if what they sold didn't work as advertised, they would have been out of business by now.

[twag4]

@Coheed, In a later post, I did expound a bit on the post you quoted. I understand what you are saying, but my intent was to speak only of the challenges of such a system. With thoughtful application, I'm sure most of the issues can and have been overcome. A two inch line will reduce flow volume too however. This would have a similar effect as some of the exhaust restrictions you mentioned. Plus, as I said in another post, piping will not cool charge as efficiently as an intercooler. Although much of the heat will have dissipated by the time the exhaust hits the turbo. I am by no means very familiar at all with the specifics of this kit, but on the big v8 kits they sell, one of their selling points is space in the engine compartment. We haven't got those same space limitations in our cars, so it seems to me like a solution to a problem that doesn't really bother us in a sense. Weight more aft is a feature though that some would argue is a plus. Rate of compression (turbo size) absolutely does factor in. Also, to be clear, I never said these systems weren't good or didn't work as well as a more traditional system. I sincerely was just speaking to some of the challenges such a system would present. I wholeheartedly agree with you on intercooler size, charge pipe diameter, etc. I discussed that in my other post. I really never intended to enter into debate, just trying to address the OP. I should have been more clear of my intent, and more complete in my post. Also, I didn't do any calculations on any volumes or flow/compression rates- as I have no idea of specifics here. I just found the whole concept of the discussion interesting, and really just wanted to join it.

[steve99]

From the STS site

http://ststurbo.com/blog/check-out-t...13-subaru-brz/

looking at the photos appears the intake pipe size is smaller (running from turbo back to engine when compared to intake to turbo, probably to keep volume lower to reduce lag. Air is under pressure in this pipe, no dramas air is compressed, possibly slight loss of efficiency. They also have optional inter-cooler.

I'm sure their would be a bit more lag than conventional turbo system due to volume of piping but sure the designers have reduced lag to acceptable levels or they would not be offering an inter-cooler as an option. Seems to suggest two things, lag due to volume of air is not a huge issue and the long piping is not suffient surface area to "lose" enough heat and act as an efficient inter-cooler.

[Coheed]

It should be added that you don't need to have an intercooler with the STS kit on their 6-8psi setup, but they do have an intercooler setup on their car pushing 9psi.