Supercharging Versus Turbo Charging

Swank Force One wrote: The correct answer is compound turbo setup.

A staged twin turbo setup. Don't the FD's have that stock. Many were replaced with large single turbos due to idle issues.

alfadriver wrote:

Keith Tanner wrote: Alfadriver, that's really interesting. I didn't know that. Every aftermarket attempt I've seen has ended poorly. A production setup would be able to deal with the noise thanks to a baffled airbox.

Doesn't surprise me- a lot of the solution depends on what you are doing. If you are an OEM, the decisions are a lot different than any aftermarket. And if you are Eaton making a kit for a Mustang, it's different than what FM will do, just for the market, let alone the resources available. Where an OEM would come up with a fancy fix to make sure the response and driveability would be spot on, Eaton may choose something different, since they have deep pockets, but don't worry about driveability as much. And FM would choose something different with less resources and different view on driveability. If I were to do another challenge, I've gone back and forth on the blower v. turbo set up. I know that my trade offs for a weekend would not even be close for the trade offs for a vehicle liftetime- so my solutions are different even IF I had the resources. Realistically, there's almost no right answer. Just one that is right enough for the situation.

Funny you should use the example of Eaton's resources. The supercharger kit we use on the NC Miata (with the Duratec engine) was engineered by Magnusson. It's dramatically nicer than any other SC kit I've seen for the Miata, with the blower integrated into the manifold along with an air/water intercooler. There's a lot of money invested in it. Because of the small throttled volume change, driveability is excellent.

In reply to Keith Tanner:

Really, I shouldn't use Eaton- they barely exist anymore.

But you get the point.

As for the Magnusson kit- I would assume that it would go both on a 3 and a Focus, which makes the market reasonably large.... Manifold replacement kits make a lot of sense- casting that kind of stuff in the aftermarket has been going on for decades.

dean1484 wrote:

Swank Force One wrote: The correct answer is compound turbo setup.

A staged twin turbo setup. Don't the FD's have that stock. Many were replaced with large single turbos due to idle issues.

The MKiv Supra had a variant as well.

I'm talking a true compound setup. Smaller turbo feeds a larger turbo.

ALL the power.

Swank Force One wrote: I'm talking a true compound setup. Smaller turbo feeds a larger turbo. ALL the power.

I realize there's no way to give a one-paragraph summary, but is that a best-of-both-worlds thing (apart from plumbing and weight)?

E.g. does the small turbo spool quickly and basically pressurize the downstream intake tract so that the larger turbo is essentially invisible until it, too, spools up? Is the exhaust plumbing engine -> small turbo -> large turbo, which I assume would slow the spooling of the larger turbo, but that doesn't matter because the smaller one's taking up the slack?

I'll take a non-answer as "yeah, you should probably google that"

ransom wrote:

Swank Force One wrote: I'm talking a true compound setup. Smaller turbo feeds a larger turbo. ALL the power.

I realize there's no way to give a one-paragraph summary, but is that a best-of-both-worlds thing (apart from plumbing and weight)? E.g. does the small turbo spool quickly and basically pressurize the downstream intake tract so that the larger turbo is essentially invisible until it, too, spools up? Is the exhaust plumbing engine -> small turbo -> large turbo, which I assume would slow the spooling of the larger turbo, but that doesn't matter because the smaller one's taking up the slack? I'll take a non-answer as "yeah, you should probably google that"

It's not really useful unless you're going for a TON of power, in my opinion.

But basically, the small turbo spools quickly, and pressurizes the air going into the larger turbo. Larger turbo then has exhaust flow AND compressor outlet flow from smaller turbo to "spool."

Basically it's a way to drastically improve powerband with huge turbos making massive power.

Sizing becomes a real pain in the ass at that point, though. I'm mulling over trying it on my new project.

ransom wrote:

Swank Force One wrote: I'm talking a true compound setup. Smaller turbo feeds a larger turbo. ALL the power.

I realize there's no way to give a one-paragraph summary, but is that a best-of-both-worlds thing (apart from plumbing and weight)? E.g. does the small turbo spool quickly and basically pressurize the downstream intake tract so that the larger turbo is essentially invisible until it, too, spools up? Is the exhaust plumbing engine -> small turbo -> large turbo, which I assume would slow the spooling of the larger turbo, but that doesn't matter because the smaller one's taking up the slack? I'll take a non-answer as "yeah, you should probably google that"

I have actually seen a real production proposal of that idea. The company that brought it is a very well known name, but not one I personally would put in a high esteem....

Anyway, the idea was exactly what you point out, but the application had a TON of questions surrounding it. To do it really well, you would pretty much need direct electronic control of the wastegateS and blow off valves.

My problems were way down the list of issues....

alfadriver wrote:

ransom wrote:

Swank Force One wrote: I'm talking a true compound setup. Smaller turbo feeds a larger turbo. ALL the power.

I realize there's no way to give a one-paragraph summary, but is that a best-of-both-worlds thing (apart from plumbing and weight)? E.g. does the small turbo spool quickly and basically pressurize the downstream intake tract so that the larger turbo is essentially invisible until it, too, spools up? Is the exhaust plumbing engine -> small turbo -> large turbo, which I assume would slow the spooling of the larger turbo, but that doesn't matter because the smaller one's taking up the slack? I'll take a non-answer as "yeah, you should probably google that"

I have actually seen a real production proposal of that idea. The company that brought it is a very well known name, but not one I *personally* would put in a high esteem.... Anyway, the idea was exactly what you point out, but the application had a TON of questions surrounding it. To do it really well, you would pretty much need direct electronic control of the wastegateS and blow off valves. My problems were way down the list of issues....

Well, there would only be one blow off valve (Unless you needed more piston area/volume for whatever reason), but yes, two wastegates.

I don't really see the point of it in an OEM environment unless it was a situation where you were trying to compete with say... the Veyron, but using a smaller motor.

Keith Tanner wrote: The supercharger kit we use on the NC Miata (with the Duratec engine) was engineered by Magnusson. It's dramatically nicer than any other SC kit I've seen for the Miata, with the blower integrated into the manifold along with an air/water intercooler.

alfadriver wrote: As for the Magnusson kit- I would assume that it would go both on a 3 and a Focus, which makes the market reasonably large.... Manifold replacement kits make a lot of sense- casting that kind of stuff in the aftermarket has been going on for decades.

Ok, now you have my attention. Is this the same Duratec that is in my Transit Connect.

Keith, do you have the general dimensions so I could see if it fits?

Someone already said it, but twincharge that sombiscuit!!!

The Magnusson kit was specifically engineered to fit the Miata application, not a generic Duratec setup. There was someone else paying the bills at the time, and I think they expected massive sales which failed to materialize mostly due to very poor engine management. When the original company bailed on their contracts, we picked it up. It's not sold for any other applications.

It's a higher level of casting than I've seen in our market, both in terms of complexity and quality. In a Mustang-size market, it would be less surprising. There are well-regarded kits in our market that look like they came out of a high school shop class...

Hal, looking at pictures of the engine bay, the basic SC/manifold package would fit. You'd have to take care of things from the supercharger out - the Miata has the throttle body on the other side so the intake plenum wouldn't fit. Still, the hard part is done - assuming there's enough room in front of the engine. What do you think, possible?

Keith Tanner wrote: On a supercharger, the throttle is before the supercharger. This means that any intercooler is part of the throttled volume. With the supercharger mounted separately from the intake manifold (ie, a "hot side" install on a Miata with the SC on the other side of the engine), you've got increased throttled volume. This means difficulty in getting the idle to behave, as the little idle speed controller can't cope. In particular, the engine speed will drop dramatically as the car tries to come to idle. Add the extra drag from the blower and it's even more exaggerated. The extra volume from an air/air IC makes this a lot worse.

That's pretty much the reason why I'm planning to go to a dual throttle body setup once I bolt the s/c to my car. It's a fairly common mod on JSRC-equipped Miatas/MX5s/Roadsters in the UK and supposedly increases the driveability immensely as it basically reduces the throttled volume back down to the stock throttled volume. It's not a super complicated setup but you need to custom fab a couple of parts and it's a bit painful for the initial setup but once you're up and running the original idle control valve can actually do its job again.

I thought about mentioning the dual throttle setups, but I didn't realize they'd become widespread instead of just curiosities.

How does everyone feel about the Rotrex Superchargers? Turbo-like efficiency, ability to intercool, and run off the belt.

Swank Force One wrote: I don't really see the point of it in an OEM environment unless it was a situation where you were trying to compete with say... the Veyron, but using a smaller motor.

think in much different sizes. 8l to 1000hp.

1l to 125hp. Which isn't a lot.

If you could tune a 1.0l engine to be very useful in a B or C car in the US, and figure out the fuel economy, we are talking some game.

Change the system so that you can do 150hp in a 1.0l, and still manage to make peak torque at 1700rpm, so you can cruise at all day long at low speeds... I could go on.

make it work, and there's a market.

On a project level for this page- I've thought about a Miata- where you change the final drive and the gearbox so that 1-3 are close, 4 is lower, and 5th is so low that you cruise at 3000rpm instead of 4000rpm.

Power it with a lightly boosted 1.6l Be agressive (not what you are thinking). But limit to 150hp or so.

How much fuel economy could one get then?

In reply to Keith Tanner:

that's a heck of a nice package.

You need to find a 3 where you can make a better to own MS3 with that. And sell it to do the same in a Focus. I'd be stunned if it didn't fit. It's more down to tuning (which is a different can, on the other shelf, next to the fly fishing hardware).

alfadriver wrote:

Swank Force One wrote: I don't really see the point of it in an OEM environment unless it was a situation where you were trying to compete with say... the Veyron, but using a smaller motor.

think in much different sizes. 8l to 1000hp. 1l to 125hp. Which isn't a lot. If you could tune a 1.0l engine to be very useful in a B or C car in the US, and figure out the fuel economy, we are talking some game. Change the system so that you can do 150hp in a 1.0l, and still manage to make peak torque at 1700rpm, so you can cruise at all day long at low speeds... I could go on. make it work, and there's a market. On a project level for this page- I've thought about a Miata- where you change the final drive and the gearbox so that 1-3 are close, 4 is lower, and 5th is so low that you cruise at 3000rpm instead of 4000rpm. Power it with a lightly boosted 1.6l Be agressive (not what you are thinking). But limit to 150hp or so. How much fuel economy could one get then?

With today's turbocharger technology, you wouldn't need a compound setup to make 150hp in a 1.0 litre with peak torque at 1700, though.

In my real world experiences (Of course, this isn't as sophisticated as what you guys get to work with), i've actually found better fuel economy with a slightly OVERSIZED turbo. I get MUCH better gas mileage in my daily driver than a stock example, despite making 2x or more the power. It's because i'm not constantly in positive pressure land.

I am intrigued about this dual throttle body idea... anyone have a link for this? is is essentially matching throttle-bodies, one before the supercharger and one in the stock location? then the cables synced up?

I actually played with the idea of changing my setup to be: filter > supercharger > intercooler (for the heck of it) > bigass BOV > AFM > throttlebody.

but I am reading here that would super crazy scary loud.... but HOW loud? like "Fast and furious" loud, or like "WTF?!?! is there a jet engine under there" loud?

Swank Force One wrote: With today's turbocharger technology, you wouldn't need a compound setup to make 150hp in a 1.0 litre with peak torque at 1700, though. In my real world experiences (Of course, this isn't as sophisticated as what you guys get to work with), i've actually found better fuel economy with a slightly OVERSIZED turbo. I get MUCH better gas mileage in my daily driver than a stock example, despite making 2x or more the power. It's because i'm not constantly in positive pressure land.

Depends on who is making it and if it's worth the compromise. It's one thing to make that work really well here in metro Detroit. It's another to make it work equally well in Denver. And another to work equally well in the high areas of China- where they have big cities WAY above Denver- closer to the top of Loveland Pass (~11k ft).

That's what this company was selling it on.

It's ok to run in positive pressure- as long as you don't need to retard the spark due to knock, or run rich due to temps or other reasons, or one bad reason. That's the real key here- sustained stoich operation at best combustion.

But that's easy...

SCARRMRCC wrote: I am intrigued about this dual throttle body idea... anyone have a link for this? is is essentially matching throttle-bodies, one before the supercharger and one in the stock location? then the cables synced up? I actually played with the idea of changing my setup to be: filter > supercharger > intercooler (for the heck of it) > bigass BOV > AFM > throttlebody. but I am reading here that would super crazy scary loud.... but HOW loud? like "Fast and furious" loud, or like "WTF?!?! is there a jet engine under there" loud?

The first Miata I know of with a post-SC TB ran open headers - and the builder said you couldn't hear the exhaust for the intake noise. Then the welds blew apart on the intercooler. But if you're running dual throttle bodies, that shouldn't be a problem.

Have any of the dual throttle guys tried putting a larger TB pre-blower with the stock size downstream? Might be difficult to synchronize them, but the blower is sensitive to pre-SC sizing more than post-SC.

As for the Rotrex, they're a centrifugal SC. Different beastie. Their biggest distinguishing characteristic is that boost is tied to engine RPM. 12 psi at 6000 rpm means 6 psi at 3000 rpm. They're very predictable, so they're easy to tune. They actually feel a lot like a worked over naturally aspirated engine as opposed to a larger displacement. Kinda fun - but on a small displacement motor, they're more suited to the track than the street.

Most of the setups I've seen in the UK use two stock TBs, one in the OEM position and another one bolted to the S/C. You basically run the throttle cable to the TB on the S/C, then run a second cable from there to the other TB. The whole setup requires a little bit of fabrication to get the second cable mount in place and a way to double up the cable wheel/quadrant on the first TB.

I think someone on Miata.net had a setup on an MP62 that used a Mustang TB on the supercharger and the OEM TB in the stock position. He had to fiddle about with the throttle cable mounting a bit more as the wheel/quadrant on the Mustang TB had a different diameter compared to the one on the OEM TB.

Swank Force One wrote:

alfadriver wrote:

ransom wrote:

Swank Force One wrote: I'm talking a true compound setup. Smaller turbo feeds a larger turbo. ALL the power.

I realize there's no way to give a one-paragraph summary, but is that a best-of-both-worlds thing (apart from plumbing and weight)? E.g. does the small turbo spool quickly and basically pressurize the downstream intake tract so that the larger turbo is essentially invisible until it, too, spools up? Is the exhaust plumbing engine -> small turbo -> large turbo, which I assume would slow the spooling of the larger turbo, but that doesn't matter because the smaller one's taking up the slack? I'll take a non-answer as "yeah, you should probably google that"

I have actually seen a real production proposal of that idea. The company that brought it is a very well known name, but not one I *personally* would put in a high esteem.... Anyway, the idea was exactly what you point out, but the application had a TON of questions surrounding it. To do it really well, you would pretty much need direct electronic control of the wastegateS and blow off valves. My problems were way down the list of issues....

Well, there would only be one blow off valve (Unless you needed more piston area/volume for whatever reason), but yes, two wastegates. I don't really see the point of it in an OEM environment unless it was a situation where you were trying to compete with say... the Veyron, but using a smaller motor.

Well Mazda does it in mid hp applications with diesels .

Like most things on the Internet, this thread has degraded until mental masturbation. Ugh

In reply to Fueled by Caffeine:

I don't expect to do compound turbos (probably ever), but the dual throttle bodies may be part of the solution for me.

I've found this thread to be very informative...

Fueled by Caffeine wrote: Like most things on the Internet, this thread has degraded until mental masturbation. Ugh

Sorry. Too much information? I agree the signal/noise ratio was a little high for the Internet.