Have a look here...

Wonder what it would take to adapt to the z...

ahm

 

Have I ever seen one? Yes.

Would I ever buy one? Not a chance in hell.

 

why?

 

1. Vulnerable position
2. Thermal shock
3. 12 feet of piping
4. Weight
5. Large single turbo

 

I almost got a remote mount turbo on my car. The only reason I dont right now is because i decided to spend a little more money for a little bit more performance. many people dont beleive in the remote mount turbo systems, and i dont know why. Every body has diffrent funds, expectations of their car and ect... Any way i hope this doesnt start a huge argument. It would work and better than many people think.

 

Oh man, I love it. Every time I see those pictures it just cracks me up.

 

1) Agree, although should be able to protect it.
2) Huh? What thermal load would it be exposed to (other than water splash addressed in (1)
3) Tubing length is supposedly not much different than an intercooled setup. From their (admittedly marketing-speak) lit, they claim less than 1 psi drop from turbo output to manifold.
4) Don't see this either - why would it be more than a 'normal' install?
5) I don't agree with this - I'm not looking for 700+ whp (and I don't think most people are). ~400-500 whp would be more than enough for me. I'm looking to make a road course destroyer, not a 1/4 mile muncher.

 

Theoretically, you might be able to protect it, but every picture I've seen has a bare turbo hanging right next to the fuel tank. Call me crazy, but I don't want a turbo right next to my fuel tank.
Same length as an intercooled setup -- without an intercooler.
Weight probably isn't that big of an issue, but 12 feet of SS piping isn't light by any means.
If you're looking to build a road racer, don't even think about this turbo setup. For a road race vehicle, you want some small, quick spooling (twin) turbos to give you a nice broad powerband. A single, non-charge-cooled turbo with laggy 12 foot piping isn't the right choice for you. During road racing, your engine would have to deal with a super heated intake charge and 4-500 HP worth of heat output for 10 laps at a time. You'll be standing in line for an engine rebuild in a month.

Regardless, I've said my piece. If you still think it's the best solution, go for it. I just wouldn't spend MY hard-earned cash on it.

 

Despite what probably sounds like me advocating the idea, I'm really not - trying to figure out what is good and bad about various setups with the goal of refining how I will go about adding power to my Z in the future. Specifically, how to reliably add power for the long term in the context of a car that sees lots of track time. Not actually racing, mind you (I know I wouldn't be competitive in any series the z is legal in, never mind the car , but hpde-style events. That's why I bought/built a SpecMiata.

I'm not trying to convince you otherwise - the nature of the discourse is someone states a theory or practice, others (verbally) bat at it, and the presenter hands back counter-arguments. I'm not trying to discount what you're saying - really - just trying to put more food on the table for whomever may stop by to eat

So, in that vein, I'm going to continue talking to your points - by all means, you can ignore me, but I hope you don't.

re point 1 - covering it. I think you're right, most people don't. But that doesn't preclude one from doing so. any covers might also be taken off so they can take pics - don't know. Yes, you'll have to deal with the heat (aluminum shield with a baffled front to get air passing over it?) to make sure a cold water splash doesn't destroy the whole works. The tank I agree is the bigger issue. Of course, the exhaust itself is right next to it anyway, so not sure how much additional protection would be required. Something, for sure.

re point 2 - again, from their lit, they claim the length of tubing, exposed to ambient air (ie, flow as the car is moving), acts as an intercooler. Surely, it won't be (nearly) as efficient. But would it be good enough? Getting real world data on turbo exhaust temp and manifold inlet temps would be needed to gauge such a statement. Of course, having the exhaust also pass that length greatly cools it as well, so less heat will be transferred via conduction into the intake side of the snail. not insignificantly, the turbo isn't accumulating heat in the engine bay as it would normally, which i imagine contributes in no small part.

re point 3 - if the length of tubing is the same between this and a traditional intercooled setup, why would the weight be different? seriously - what am I not accounting for? on the plus side, that weight is very low, and runs front to rear, not all at the front of the car.

the one thing i will definately disagree with is the need for, 'a nice broad powerband.' au contraire, i want a much bigger (ie, any) top end hit - 1000 rpm of powerband is enough. 1500 would be perfect, and 2000 would be manna from heaven. that's what the gearbox is for

in my particular context, i fully expect to go into the project with a built motor. given the propensity for otherwise stock FI motors to go boom (granted, most with inadequate/poor tuning), i don't expect a stock bottom end to last worth a damn. frankly, i'm surprised we haven't heard about more stock motors letting go at hpde's.

like i said, i'm not advocating this setup - i'm honestly curious about real-world experience with it. so far, the closest thing to a box-stock 'system' being offered via a vendor that I'd consider is probably APS single turbo (still not released yet, right?). and anyway, i won't be embarking on this journey (that is, buying parts) for probably a year. i'm still asking n00b questions and soliciting slaps to the head

ahm

 

with the remote mount turbo system on the 350 the hp should be in the 340-360 rwhp range...the turbo wouldnt have that much lag...i was told it would spool around 800 rpms later than a single front mounted turbo. But who knows theirs not a remote mounted 350z (that i know of).

 

I contend that a single turbo, mounted in the engine bay, will typically (not necessarily always) spool a little bit slower than a properly sized twin turbo setup. I further contend that the rear-mounted setup will spool further after that.

If you say that an engine bay mounted turbo spools at 2500 RPM, and the rear-mount spools at 3300, that's a HUGE difference, IMO.

 

Point taken. I'm glad to "chat" with another forum member willing to discuss an idea without too much prejudice. I apologize if my earlier comments were a bit harsh -- I'm tired of seeing the usual posts with people trying to figure out the cheapest fastest way to xxx RWHP where cutting corners is not only acceptable, but encouraged.

I think we see eye-to-eye on covering the thing up, although I contend that dealing with this is probably more work than it's worth. I'd still go with the tried-and-true TT solution in the engine bay.
As far as weight goes, I was willing to back down from that one. Given that it doesn't include an intercooler, the weight would probably be more or less similar to any other single turbo setup.
In terms of cooling, I have a few points to make. One - the turbo actually works by converting thermodynamic energy into mechanical energy to compress the intake air. It thrives on exhaust heat. By placing the turbo 8 feet from the exhaust ports, you lose a lot of the energy that a TT setup 1 foot from the engine would make use of. Even a normal single turbo won't be as efficient as a twin turbo setup on a V-engine. The compression process heats up the intake charge due to adiabatic inefficiency, and this might be offset slightly during the travel back up to the engine, but (as you agreed) probably not nearly as efficiently as with an intercooler. The hotter intake charge will yield less power and will ultimately generate more heat in the combustion process, leading to higher water temps.
I couldn't agree more about the top end -- I think the VQ's stock top-end power is atrocious. I understand why Nissan tuned the engine the way they did -- low-end grunt is addicting (and useful on the street), but I'd give up some of that low-end torque in a second to make power out to redline (and beyond). With that said, I can't tell you how many times I've been forced to downshift at the exit of a corner because I hit the relatively low fuel cutoff. I'd prefer if a turbo setup made lots of power from, say, 4000-7500 RPM. With a raised redline, hopefully I could avoid the 4000-5500 RPM region, but right now, the gearing and redline force me to visit that range a lot more than I'd like during the average HPDE. Obviously track design plays into this quite a bit, but I've heard this sentiment from others as well. 6600 RPM just doesn't quite mesh with this gearbox at the track.

My feeling is that a quick-responding, fast-spooling TT setup would achieve these goals the most efficiently. The only area that really concerns me is the FMIC in front of the radiator. I suspect that some custom airflow ducting up front and a larger radiator might alleve this issue. I'm still doing my research as well -- I'm probably at least 2-3 years off from having the cash to build my car the right way.

 

as a side note, I'm envious of the Spec Miata. I wish I could afford to play with the Z and build up an SM at the same time.. My funds are too limited at the moment, and I have to focus on one thing at a time. I'm trying to convince my G/F to buy a well-used '90-'96 Miata so she (we) can run it at the track. She's too scared to drive my Z for fear she'll wreck it.

 

agree

 

Advantages seem to be:
1.) Easy install (can probably do it yourself)
2.) Probably the cheapest FI option for hardware costs (comparing all turbo and supercharger options). The lack of intercooler helps costs a lot. The oil return pump and extra tubing might eat into the cost savings though.
3.) Between 1. and 2., it's probably the cheapest option when considering both hardware and install costs together.
4.) It doesn't touch the cat placement and therefore potentially doesn't apply to emissions laws. I am curious about the lifespan of the cats which will obviously run hotter than normal in this configuration.
5.) weight distribution
6.) there's A LOT of room where the muffler goes on the Z.

I'm not interested in this as a product option myself, but I could see it appealing to people that might normally buy a centrifugal supercharger. I bet the remote turbo could get better performance for cheaper.
--
Jeff

 

Concur. One of the things I find most sad about many of the grenaded motors is people's singular focus on achieving xxx RWHP to the detriment of a car that is actually fast and reliable. Their money, their dice to roll I guess. Me? I'll be happy with about 150whp additional to whatever it dyno's stock (a porta-dyno at VIR in the fall said ~225).

For simplicities sake, I'm probably going to go with a single turbo system. The motor is torquey enough that some minor lag is worth the fewer parts (and frankly, cost) of a single to me. Rear-mount? Probably not, but I'm not averse to looking at it as an option...

I need to do some research on this. I see people bandy about the dependance of a turbo on heat, and I don't understand that, at least not all the ramifications. Obviously, as the exhaust cools, its density will rise, while volume will correspondingly decrease. However, the mass of exhaust gasses will not change. If the exhaust tubing diameter does not increase in diameter, I think velocity should stay the same. The question I have really revolves around whether the difference in gas density changes the velocity. If it does, then the turbo design would have to account for the lower velocity - but keep in mind the mass would stay the same.

Clearly, intake temps are major issue. As I said in my original response to you (I think), I would like to see hard numbers from squires (rear turbo company). A significant component of raised charge temps revolves around the compressor wheel efficiency at a given volume and pressure. Ie, in the WRX world, it is not uncommon to run a significantly bigger wheel at lower PSI, yet provide a much larger intake charge (by volume), and hence gain significant hp. The stock turbo just isn't efficient at the RPM's it sees under max load. I'd also be much more worried about preignition rather than water temps because of this problem. One of the things squires says about this is that the rear-mounted turbo, because 1) it is farther away from the manifolds, and hence the exhaust itself is cooler, and 2) the turbo is exposed to much more air, cooling it. They claim this means the turbo is 100+ degrees cooler than an underhood design (off the top of my head). A signficant portion of the heat added to the intake side is via conduction through the housing of the snail. If their claims are true, that offsets, at least to some degree, the lack of a real intercooler.

I'm not so worried about what the actual RPM's are, so much as where among the range the power is, and how much of it there is Concur 100% with lack of top end - much more well suited to the Murano and FX35 than a sports car. A higher redline would be good too, but of course, then they'd have to fix the damn rods, and correct whatever godawful cam timing/duration is in place. If I could make an additional 100whp at 4500 and above, I'd be OK. Just don't start tailing power off at 6K when redline is 6600.

Like I said, I'm not that worried about 'fast-spooling'. The motor is torquey enough to get out of its own way, so I'm looking for simplicity, matched to my target power levels, and reliability. I'm not heading into this anytime soon either. I haven't run a full season with the specmiata yet, so gauging what those costs are going to be is making me hesitate dropping anything into the Z. I did do a stoptech kit up front, but that's it. Only reason I did that was the realization of just how completely inadequate the stock units are. Had I not been running at Pocono where the oval section is coned to turn you into the infield, I would have run dead-on into something. Thankfully, I just killed a couple cones, and watched the smoke pouring out of the front wheel wells. I'm at least a year if not two from diving in as well. Just trying to play all the angles early in the game before deciding on a path...

ahm

ps and yes, the miata is a blast. no power to save you - you're either smooth and good, or back of the pack. as they say, its a momentum car. drive well, or lose badly

 

The problem with the loss of temperature in the exhaust stream has less to do with density/velocity and more to do with the simple fact that lower temperatures mean less energy. Less energy in the exhaust means less energy to spool the turbo. I'd also be very concerned with intake temperature. To my knowledge, the only people have lost engines while running FI so far has been due to detonation. Increased intake temperatures promote detonation. You could add an intercooler to system somewhere under the car to help reduce temps so maybe this wouldn't be too much of a problem.

One potential problem that hasn't been mentioned is the lack of water cooling for the turbo. I'm not sure if other kits use water cooled center sections, but every OEM uses water cooling to extend bearing life and to allow for tighter tolerances for faster spool and greater efficiency. I'd be nervous about using a turbo without a water cooled center section. At minimum, you should add an oil cooler to remove the heat from the turbo's oil (turbos typically run at 1k+ degrees).

What I've been seriously considering (I'm a trackday junkie myself) is a Vortech SC. The biggest power gains are on the top end and there's no lag at all as long as the motor is reving high enough. There's even a fair bit of data in place for tuning (maps).

Sorry for the long post.

 

you're sorry for long posts - hah. guess i should be beaten then

Quoted from STS FAQ:

Q: Don't turbos have to be really hot to work properly?
A: Putting a torch to your turbo and getting it hot doesn't produce boost. What produces boost is airflow across the turbine which causes the turbine to spin. If turbochargers required very high temperatures to produce boost, Diesel trucks and Methanol Race cars wouldn't be able to run turbos. However, each of these "Low Exhaust Temperature" vehicles work very well with turbochargers when, like any turbo application, the turbocharger is sized correctly.
In a conventional, exhaust manifold mounted turbocharger system, the extra heat causes the air molecules to separate and the gas becomes "thinner" because of the extra space between the molecules. This extra space increases the volume of air but doesn't increase the mass of the air. Because the volume is higher, the velocity of the gas has to be higher to get it out in the same amount of time.

By mounting the turbo further downstream, the gasses do lose heat energy and velocity, however, there is just as much mass (the amount of air) coming out of the tailpipe as there is coming out of the heads. So you are driving the turbine with a "denser" gas charge. The same number of molecules per second are striking the turbine and flowing across the turbine at 1200F as there is at 1700F.

This I agree with 100%. They do use the oem oil pump to get oil to the turbo, and an additional vacuum pump to pull it back to the sump, but on the face of it, is something that gives me serious pause about using this solution. Especially in a track environment, where it is going to be at full load at probably 85% duty cycle.

I guess I just have a thing for turbos. Don't know why. Probably should give the SC a more fair assesment, but I don't like the whine (but some reason the whoosh of turbos, I do). Not to go even farther afield than we already have, but what kind of numbers are people getting with the vortech?

ahm

 

I was looking at putting a STS on my tahoe and test drove a 4.8L pickup truck. Let me tell you it was a torque monster with scary power.

I ended up spending the money on a stillen SC for my Z, but it was a difficult decision. I don't know about the engineering or lag due to extra piping, I just know the truck was a blast to drive. I've ridden in a very tricked out supercharged lightning that was running high 12's and this truck with just a STS felt very similar.

I am a believer for a big V8, I am saying nothing about rear mounting for the VQ.

 

I've seen similar kits, where the turbo is remote moutned like this. This design was originally designed for trucks, to help with towing power. But The design I've been reading has been very effective, even with all the piping etc..
This may not be the best performance turbo setup for absolute power, but it would be a much simpler install IMO. Also, if you remove the stock muffler in the back, there's tons of room to perform a setup like this.
Turbo lag may be a little bad, but the kits that are out there that i've read up on don't have too many negative side effects.