Alright... TRD has a SC coming out that I've heard around here is going to run about $4,500. There is a lot of talk on the forum about aftermarket turbochargers as well. From the looks of it, at least some of them are going to be less expensive than the supercharger, but we don't have real performance numbers on either one yet. Can anyone who understands this stuff better talk about the ups and downs of going with each and if you know, tell us which is going to make more power, etc.? Thanks

 

it depends on who makes... but turbos seems to last longer and not mess up the engine as much and superchargers when you resell turn people off alot...

 

I should probably leave this for Nick@AGP, but I'll take a stab. Superchargers are belt driven (typically), and it uses that belt to turn a turbine which, in turn, creates boost which is then forced into the intake, creating your power gains. They're not usually intercooled, allthough some now are, so they don't usually run more than 5-9 lbs on pump gas without detonation. Since it's belt driven, it's almost always creating boost (even at idle!), so most of the time, there's very little lag and almost instantanious power on demand at any RPM.

Turbochargers (technically, it's a turbosupercharger, but we'll leave that for another day) uses the vehicles own exhaust pulses to move a turbine in a turbo (or spool it). Turbos will typically run a lot more boost than a s/c, but with more work involved. If low boost is run, we'll say less than 8 lbs for arguements's sake, it may not even be intercooled, but turbos are typically running over 10lbs, which requires cooling of that charge before it reaches the intake, for more power and less detonation (which go hand in hand). Since they rely on the engine's exhaust output to spool, it may not make much power before, say 2500rpm (but that varies wildly depending on the turbo used), but once it spools, power usually comes on hard and fast. The smaller the turbo, the faster the spool at the expense of top end power. Bigger turbos spool slower, but give greater power on the top end.

They both have a few things in common. Both usually require additional fuel to counter the additional air going into the intake to prevent a lean condition, which is usually the culprit for blown engines. So a good fuel system, and some way to manage and tune it are absolutely essential. Alot of folks with superchargers can get away with a "pretuned" or premapped ECU (I'm not going alot into that now) that will take the extra air into consideration when providing fuel and spark and timing and all that., while people with turbos often need an aftermarket standalone system or fuel computer to tune, due to the varying air and fuel conditions at different RPM (ie less fuel before the turbo spools, more after).

They both have their pros and cons, and both can be absolutely reliable if done right. There's not one that's better or more reliable than the other, it all comes down to tuning the car. But as a generality, s/c's will make less power with less problems than turbochargers. And vice versa.

Again, before the flames start, I've stated all this in general, or generic terms. There's exceptions to everything, but this is the rule of thumb for the most part.

 

I totally agree with Mudd! He has a very good explanation. In our case, the best thing for reliability would be to use the TRD supercharger... It is in teir best interest to design a power adder that will not affect the reliability of the car. Otherwise, think about all the warranty claims that Toyota would have on their hands. If you do get an aftermarket turbo, it will surely give you more power than the TRD. Aftermarket companies only care about a good dyno number and short term reliability; they're not trying to design a system that lasts 100K miles. They may say they are, but I disagree.

 

No reason a turbo kit can't be perfectly reliable. Several manufacturers take reliability into account.

Basically, a turbo will outperform a supercharger in everyway. The TRD scion blower ia centerfugal unit, which makes linear boost. If it runs 7psi, this means 7psi at redline, and a straight line of boost going up. Think 7psi at 6000rpm, 5.5psi at 5000, 4psi at 5000 and so. A turbo, once at full boost holds that value. This makes a better powerband and more torque, which equates to a faster car. On a 2.4L with 9.6:1 compression, a good size turbo should come in around 3000rpms or faster. So if your running 7psi on a turbo, you'll have 7psi from 3k-6k.

Expect to see a nice kit come out around $2500. All these people claiming 350hp on turbo and stuff are just making stuff up. No one knows how much power the car will make or handle. There is no reason a base turbo kit with reasonable boost 5-7psi couldn't make 220-230fwhp on a TC. If the TRC SC is rated at 220hp at the crank, figure 190ish to the wheels if that.. Even at the same power levels, a turbo will outperform a SC, but even a base turbo kit should make 20-40hp more than a supercharger.

Turboing these cars is all going to depend on how the ECU like boost, and how the factory internals are. I see no reason that the car can't make 220-250fwhp perfectly reliabily. We've seen 390-400hp out of stock honda motors which aren't suited for boost nearly as well at the TC.

Look forward to a nice turbo kit coming out for the scion from a very reputable shop that has been turboing cars with great results and great reliability. I don't think a single one of their customer cars has ever blown up.

 

I plan on going with a turbo on my tC. You get more bang for your buck with a turbo than you do with a supercharger. Since superchargers are belt driven, it's going to take power to get power. Thats why most 4 cylinders have turbos on them(wrx, srt4, 1.8t) and v8's have superchargers(cobra, lightning, z06). If you want to increase boost on a supercharger, you're going to have to go out and buy pullies. On a turbo, just crank up the boost and hold on tight.

In the long run, superchargers are going to be more efficient and durable which is why TRD is making them. But who wants reliablility over the jaw dropping sound of a sequential blow off valve?

Whoooosh! :D

 

That's my thought as well. I'm very interested to see if the stock ECU will adapt to a turbo- or supercharger running 7-10 pounds of boost. Hand in hand with that goes the fuel injectors and fuel pump. If the ECU works, and the injectors and pump can keep up, aftermarket forced induction will be a cinch.

I feel optimistic about the ECU. Since TRD has been developing the supercharger along side the development of the car, and since they would want to make it as economical as possible, I have a strong feeling that the stock ECU will be used. It would have been very simple for the factory to make sure the range of the airflow sensor and ECU are broad enough to account for forced induction (something that's difficult to fix in aftermarket without workarounds or standalones.)

In any case, by the time I'm ready for any kind of forced induction (3-5 years, I'm not looking to void my warranty as soon as I get the car) I'm guessing there will be a number of options.

 

what else would someone have to get, cause i know you cant just get the turbo itself you need other things, i was wondering what these things are

 

I am in pretty much total disagreement with the statements I am reading...

#1 - top fuel dragsters exclusively use belt driven superchargers... they make over 6000hp...

#2 - nick@agp - you are totally incorrect about what amount of boost is made by a supercharger... your description says that a certain amount of boost is made at a certain rpm and you couldn't be further from the truth... by nature a centrifugal pump will make more pressure at a higher rpm, but that is based on pumping against a "wall" an unchanging flow path... here's how I can break it down for you... at 3000rpm the engine is needing 2.4 Liters at 1 atmosphere (14.7psia or 0 psig) so 1 * 2.4 * 3000 / 2 = 3600 liters of air / min... so the supercharger we hope to make 7psi of boost... so instead we need about 1.5 atmospheres (21.7psia or 7psig)... so now we need the pump to make 1.5 * 2.4 * 3000 / 2 = 5400 liters of air / min... so the pump is pumping 5400 liters to 7 psi... now we rev the engine up to 6000rpm... the math is the same... just sub in 6000rpm... so 7200 at 1atm vs the s/c setup using 10,800... but from your description you are saying that engine's needs are declining in relation to the pump's output, to get higher pressures the ratio from the 10,800 to 7200 liters would need to be different from the 3600 to 5400.... you are saying that somehow the supercharger isn't going to pump the same ratio of air...?? but you are saying that the turbocharger has this capacity?? they use the same impellers in the same shape housings - one is belt driven, the other is exhaust gas driven... the belt drive ensures that the pump (the s/c) is matched to the engine speed... the only factor that is changing is the efficiencies of the pumps through the rpm range, but this is a whole nother thread... but the turbos and s/c's suffer the same inefficiencies when it comes to pumping losses...

the reason that the pressure levels off on a turbo setup is because of the blow off valve... it is dialed into that pressure and releases the compressed air back to the atmosphere to keep that level... the blown off air is wasted horsepower...

I size, buy and install centrifugal pumps for the petroleum industry... I have size turbos for large diesel engines... and I have a degree in Mechanical Engineering... this is just to back my words, I have half a dozen books directly related to s/c and t/c engines under my belt... I am not trying to throw mud, but I am pointing out the discrepencies...

 

Turbo v8s rock. Not all the v8 guys go supercharged. Alot of them go turbo, and are fast as hell.

You can put a BOV on a supercharger if you want the sound. Saying a supercharger isn't as efficent is not accurate. You have to say which supercharger vs which turbo. There are thousands of turbochargers and hundreds of different superchargers. In general, a turbo is more efficent.

As for how the ecu will like FI, I'm also opptimistic. Since its a MAS system, it should be able to account for the additional airflow by itself to a certain degree.

As for what you need to put a turbo on, you need a turbo kit. Basically, manifold, turbo, wastegate, o2/downpipe, and some piping to hook it up. Additional things maybe a BOV, Boost controller, boost gauge, intercooler and so on.

Personally, I would love to see a cheap turbo kit come in around $2500 that runs low boost, non-intercooled, and then lets you add options later on as you upgrade.

 

Top fuel dragsters also can barely turn the supercharger vanes at idle. The engine by itself probably makes 800 to 1000 hp, but the drag of turning such a huge blower is all but eating the engine's actual power. Turbochargers and superchargers are about improving an engine's Volumetric Effeciency....eg how efficient the engine is at making power per unit of air shoved down its throat. The more air you can stuff in, the more power it makes, if you add fuel. The top fuel dragster is not a good example as it is optimized exclusively to be ran on the blower, at full boost, for a quarter mile at a time, being rebuilt between runs. Doesn't make a very good street car.

A supercharger can provide a hefty shot of power for what is essentially a bolt-on modification. They have different tendencies, depending on whether they are belt-driven or centrifugal. A belt-driven blower will make less boost overall, but over a wider RPM range, and is almost 'instant-on'. A centrifugal blower will make boost that is linear dependent on RPM. More boost the higher you go in the rev range.

A turbocharger is a much more complicated installation and requires more precise fuel tuning. A properly sized turbo can give you a mild kick low in the RPM range, some crazy midrange punch, and a hefty top-end rush.

With the way the tC/Camry engine is built, you could probably get more power and better response out of a belt-driven supercharger or a mid-sized intercooled turbo setup. TRD is going with the centrifugal blower because 1) They've used basically the same setup on every TRD supercharger, and have the basics down; 2) the blower is essentially a bolt-on and is hard to break anything with given non-abusive usage; and 3) Because most people would be satisfied with the extra kick the blower will give. Geeks like us, however, may want to explore other options.

 

In general, a centrifugal supercharge gives you a linear boost curve. Depends on the motor.

Top fuel dragsters run superchargers cause turbochargers are outlawed, not because they make more power or are more efficent.

A blow off valve has NOTHING to do with the pressure a turbo puts out. You are mistaking a BOV and a wastegate. A bov simply vents air between shifts to prevent compressor surge. A wastegate vents excess exhaust (not boost) past the turbine to limit the boost a turbo makes. By limiting the amount of exhaust flowing past the turbine you can limit the boost a turbo makes.

To say a turbo takes more tuning than a supercharger is not true. Any forced induction system needs proper tuning. Any engine in general does.

The TRD scion blower is a vortech unit. It says vortech right on the side of it. The other TRD blows are roots style blows, which are vastly different. To say its hard to break something with a blower is 100% wrong. If it is tuned badly, it will blow up just as easily.

 

volumetric efficiency is the comparison between what you expect an engine to move in liters of air vs. what it actually moves... so a 2.4L at 100% efficiency will move 2.4L, but it really runs at say 75% efficiency, so it only move 1.8L of air... but a 7psi boost will make it move 3.6L of air (this is all per two revolutions)... this has NOTHING to do with how efficiently the engine makes power... you are confusing thermal efficiency... this is down in the 20 to 40% range...

turbos cause backpressure on the exhaust system... superchargers steal horsepower through a belt... efficiency is a side issue... the swap here is power on demand vs turbo lag...

I also thought that estimates were putting the s/c kit for the tC closer to $3500?? they are promising over 200hp which means it will make more than 5psi...

the TopFuel reference was to point out that turbos aren't the only thing used in high horsepower applications... a roots type blower designed to make 35psi or more will of course take tons of horsepower to turn, and idle will be a _____ for any of the super tall, super advanced camshafts...

A centrifugal supercharger does not have to give you a linear boost curve... that is just what people do to reduce the part count... you can use the BOV setup with both... the turbo is pumping the same air, the same way... (refer to page 71 on Corky Bell's "Supercharge") the turbo is making too much power so you can use your WG, but with a supercharger you can level off this linear boost curve by dialing in the pressure with the BOV... no confusion...

yeah, I bet there will be people trying to buy the Vortech and thinking they can save money by building the rest themselves... take the number of hours and multiply by just minimum wage and you'll see that most t/c or s/c kits are a great deal... remapped ECU, correctly sized injectors, the list goes on....

 

I thought centrifugal superchargers build boost exponentially? Meaning if you spin the supercharger twice as fast, you make four times the boost, 3 times as fast gets you 8 times the boost, etc. I believe that's why a normal supercharger kit will give very little low end boost, otherwise boost at the high end would break things. I guess you could couple it with a wastegate or BOV to keep boost levels at the high end reasonable.

Anybody know the specs on the other Toyota superchargers? What kind of boost and horspower do they make?

 

It was my understanding that all of the TRD units were centrifugal Vortech units. If that's not the case, I'm sorry. Lemme poke some more...

When I said 'turbos require more tuning' what I meant was this: If you know the characteristics of the supercharger you've got, you can predict the boost at certain RPMs and how much more fuel is required. With a turbo, you need more precise situation-dependent fuel/ignition control. In other auto applications, most SC kits come with a chip/piggyback computer and they'll work fine. They usually wont make much power, but most of the time, nothing breaks. A TC kit that doesn't have a well sorted fueling solution will make good power until the instant before a conrod punctures the side of the block. This is a generalization, but is generally true.

If any of you read Sport Compact Car and are familiar with the 'Disco Potato', a setup like this would be ideal for the tC, methinks. I'm no pro, though, so that's only a guess.

 

well you are correct, but the same is true for a turbo, but you don't have the control over the impeller speeds, so you need other devices to control the boost that is being made or you'll blow the engine... you COULD use this same mentality for a centrifugal but people usually choose to use fewer parts because they CAN

most of the other TRD superchargers are twin screw compressors, they make great boost at low rpms and their efficiencies fall off as rpms rise... without intercooling you are pretty much limited to 5 to 8 psi of boost based on the engine's compression ratio... when that fuel air mixture reaches 1200 to 1300 degrees it is gonna self detonate...

you can estimate horsepower by using volumetric efficiencies... take the boost and add it to 14.7 (atmospheric pressure) and then divide it by the atmospheric pressure and you will get a number... always more than one... but usually less than say three... then multiply this number times the stock hp...
so for the tC, I estimate the s/c to make 5psi... so ((14.7+5)/14.7)*160 = 214hp so maybe it'll make 4.13, so the number will be closer to the 205hp that I have seen estimated by others...

 

hey nick, are you guys going to help us all out and produce a turbokit for the Tc? Or you just going to keep creating those monsters known as SRT-4's?

 

Monster SRT4s.

Bah, our DSMs are way faster than our SRT4s. I wish would could just stick to DSM stuff because our DSMs are running 9s and 10s all over the place. Last week alone we had several customers run 10s. Check the main page for detials.

Right now, we planning on partnering with solid technology to help them produce a kick ___ kit. We are too busy to deal with Neons, DSMs, and Scions, so we are helping them produce one kick ___ kit. They have used our turbos to make 500+ hp on several 4 bangers and we fully trust them to do one hell of a job on a tC. They bought a tC in order to make it a beast. I bought mine to get around town.

 

:twisted:

 

I'm afraid I'll have to disagree w/ya there. The particular reason the big 8cyl. engines have s/c's is because they're thought of as "drag strip" cars. The wrx and the other little 4bangeres have more of a rally/race theme and weren't exactly meant for putting on a strip.
and
To be quite honest, I'd probably purchase a factory s/c car over a factory turbo'd car. When it comes to turbos, the boost isn't constant, therefore the engine is receiving uneven wear. Seems to me that a supercharger would keep your engine and parts working smoothly and, more importantly, consistently.

The majority of people, while they may be a bit confused, aren't going to be pushing for every last bit of power. Most people, if they're smart, will realize that a dragstrip tC supercar just isn't practical. I believe the S/c was put out for people who just want a fast, sporty coupe and aren't as much looking for the numbers, but ride quality, control, etc.

Not trying to flame anybody here, just throwin' out my .02