StormX02

I know I'm going to get hated on because of this, but...

I really don't understand it, but my preference over turbos over superchargers seems to be a psychological thing. It makes me more excited to get a huge rush of power after a short period of weakness than to have a good amount of power throughout. I can't explain it. It's kinda like how people innately prefer dogs over cats. If someone said "I don't know" when you asked them why they like dogs more than cats, would you automatically think that they liked dogs because they're the "IN" pet?

And yes, I love the sound of a blowoff valve. So? I'm not going to lie and say I don't, because I do. But it's not just because of the sound that I prefer turbos, else I'd get one of those simu-pshh adaptors to put in my muffler. You can flame me all you want, but at the end of the day, we ALL love the sound. It's simply whether we choose to lie and be accepted, or be a man and take the flak.

[/truth]

KAuss

I seriously don't like the sound... I love the WRX because it has a recirculating BOV (well it isn't a BOV if it don't blow) so there was no sound at all, cept the spool which I'm more fond of...

I'm a huge audio buff... I can't even stand muffler noise... I don't like road bumps and wind flutter... I want my car to be as silent as possible while packing a lot of heat... I need the power to move the extra weight....

So not everyone likes the BOV, I personally dispise it...

bunni

Maybe I'm not understanding your point but I'm going to have to disagree with you on this. Putting turbos on larger engines will certainly not increase spool time - large displacement engines pump out more exhaust, spinning the turbo faster, sooner.

Maybe your two points here are unrelated, but it's important to note that F/I is necessary in rallying because engine size is capped at 2 liters. If you're saying that as the popularity of rallying grows people will become more familiar with turboed cars then I agree with you. Also I'm not too big on the drag scene but I thought many of the dragsters were turboed - and running exotic fuels.

KAuss

Read up on topfuel... Or any NHRA cars that don't run on regular gas... These are cars that usually sport large blowers that can't bare to lose even a millionth of a second to wait for the F/I to kick in...

As for the larger displacement spools turbos faster, why wouldn't they put a large single turbo in big cars? Most of them come with twin turbos... Now the new ME412 sports quad turbo being a 12 cyl engine... You might get more exhaust, but usually having ONE big turbo to increase enough pressure to support a larger displacement would mean a HUGE turbine... That usually results in a lot more lag... You'll get the bigger peaks tho, but really poor response... The same size turbo from a 4 cyl put into a 6 cyl WILL spin faster, but the gains wouldn't be as significant... This is like saying put a smaller motorcycle turbo in a 4 cyl car and have that spool at idle...

Yeah and I did mean that when the new sports like Rally and Drifting becomes a bit more popular, then people who favor turbos for constant loads (usually track / circut racing since you don't need power to make power) the trubos will become more popular and widely used...

I just want to say one last thing... Buses here use turbos, if anyone like the BOV sound, go drive a bus... :D

bunni

That was my point exactly, and of course larger turbos will have increased spool time... but saying the gains 'wouldn't be as significant' is over simplifying it. Gains are decided by the efficiency of the turbo, and how much air can it push (CFM). Which is why people check out a turbo's compressor map when selecting a unit rather than just relying on peak CFM.

Garrett's GT28RS is performing great on 4 bangers as well as 6s. It's efficient, spools quickly, and moves a lot of air for its size. Obviously comparing motorcycle turbos and v12 quad turbo setups is going to the extreme ends of automotive turbo applications - an efficient turbo can be applied to 4, 6, and arguably 8 cylinder setups.

Undersizing a turbo for a given application, what I think you're talking about when you mention a 'turbo from a 4cyl' is something that really only car makers (like Volkswagen w/the 1.8t) and autoxers do. People like to feel that off the line performance, rarely do people go for top speed runs on a test drive (or ever), and just saying twin turbo can give a potential customer a stiffy.

...that is why I think auto manuf undersize turbos and run multiple turbo setups, I don't consider it more efficent, or more appropriate than a single turbo setup, it's just more appropriate for the auto manufacturers goals.

bB384

TRD hasnt yet made a Turbo kit probably for the same reason Mugen hasnt for Honda. Because a Turbo DOES add more wear and tear to your car, it lowers your gas mileage. (Unless you have an Apexi Super Air-Fuel Controller to make your car run super lean.) Also if the Scion xA/xB came with a turbo, the boost can only go so high since the 1NZFE has a 10.5:1 Compression ratio. Boost a little too much (maybe 1
or 2 psi more) and your engine goes bye bye!

Superchargers add leass wear and tear compared to turbos, and they dont produce as much heat in your engine bay. Superchargers are like an NA Tune combined with a Turbo set up, best of both worlds as I see it.

TRD stands for Toyota Racing Development. the Racing division for toyota is Toyota Motor Sports. Those are two divisions. One makes parts, the other uses the parts.



....the preceding was my 2 cents. Sorry if i sound mean, I didnt mean to.

itimebomb

well it doesn't really matter why they decided to put the S/C on there. from what TRD told me when they came to visit was that A) they had already designed a S/C for the camry/solara and B) it takes less time to install for the techs and a lot less if any tuning.

aside from that, an interesting little tidbit they told us was that with the T/C S/C, this is the first time EVER that Toyota JPN has released the computer codes for any reason. up until the T/C any FI that TRD made was pretty much guess and check. they've always stayed like in a vault in Japan. so i thought that was kinda cool.

bB384

Another note "There's no replacement for displacement!" Skylines have like a 8.5:1 compression just so they could boost so much. And, I know of a guy with a CTR motor in his civic, he beat a Skyline GTR-33 on the freeway. I know both of them and they afgree the Civic was FAST! I prefer both turbo and NA. for scions Turbo would be okay but i wouldsnt go get a T3 or a T3/T4 hybrid. I would probably get a nice T25.

justinb

Turbo lag is only a problem with a poorly-sized turbo for the application or a motor running too little compression to have a little response off-boost.

Besides, the TRD supercharger for the tC is a centrifugal unit - which is the compressor side of a turbo spun by a pulley instead of an exhaust-powered turbine. As such, it exhibits the same spool-up problems that people blame on turbos.

You can gear the centrifugal sc to come on early, but at the expense of top-end power.

-Justin

ChrisSS

regaurdless what any detailed explination here was said. the point is this.

Turbo = less engine life and smaller power gains at higher boost
SC = more engine life and bigger power gains at smaller boost.

simple as that..

Reasons?

Turbo = Higher RPMS while turbo spools up
SC = Instant power gain from the moment you step on the gas.

monsoon725

You have got to be kidding me. Constant boost? I don't think so. The boost that any supercharger makes is 100% related to rpms that the motor is spinning at. Why? Because all superchargers are belt driven.

A S/C that makes peak boost of 10psi at 6800 rpm is NOT making 10 psi at 3000rpm

You can argue until the cows come home about whether or not a supercharger is better than a turbo and vice versa. Roots type blowers do make torque down low; centrifugal blowers like the one that will be on the tC (per pictures) will not be a torque monster.

iZero

There are some advantages to using a supercharger instead of a turbocharger. A supercharger will provide a linear power delivery throughout the RPM range. On average it's easier to make a reliable supercharger over a turbo. You need to worry about heat with a turbo moreso than a supercharger, as it's bolted onto the exhaust and compressing air.

Now let's think about Toyota's goals with the tC. They picked the 2.4 liter I4 from the Camry for it. Notice they did not select the Celica's 1.8. Why? The 2.4 provides better power delivery through its entire range. Its powerband is wider. While high RPM engines making big numbers for their displacements may excite you on a spec sheet, in the real world, they tend to be much less usable.

Now back to the supercharger. Toyota has two concerns: the character the forced induction will create and reliability. A supercharger will enhance the engine's feel positively. The turbo will add lag and make it feel peaky. If they weren't concerned about a linear feel, I doubt they would have selected the engine they did in the first place. I'm sure you can still find a Celica if you want one. Personally, that's not the type of car I want to own. That's why I'm considering a tC.

So why use a turbo? Parasitic loss. As a supercharger is constantly being driven (unless it's on a clutch, in which case it sort of is). This means a certain amount of energy must be expended driving it. Thus, if you are looking for the absolute highest output you can get, a turbo will proabably work better. The TRD unit isn't about extracting all it can out of the engine. It's about enhancing it.

monsoon725

Well written. Another slight advantage of the turbo that goes along with parasitic drag is fuel economy. A supercharged car will use slightly more fuel than its turbo counterpart regardless of whether or not both drivers have a lead foot.

As was previously mentioned, turbos do have a greater degree of "tunability" whereas when it comes to a supercharger, the amount of boost you can make really comes down to the size of the pulley. Sure you can keep decreasing the size of the pulley but with that comes issues of belt slippage.


Adrian

khrys771

i think another reason is that toyota has had supercharged engines as long as they have had turbo engines. you guys remember the '88 - '89 factory SC mr2. not to mention that engine is a 1.6L 4AGZE, and in JP was SCed till around '95 or so. as for the xA and xB it just seems proper to do so and make a SC and continue for that small of a displacement.
but for the tC 2.4L its honestly more personal choice, you know for a person who really doesn't know that much about cars, a SC is prolly better. since it is belt driven that person honestly will only have to worry about the belt breaking, but on the other end the turbo is more technical, and i would think requires some knowledge of how it works. as you have a wastegate to limit boost, an intercooler to cool the compressed traveling air, also the oil supply, since the turbo does spin in excess of 100,000+ RPM.

but my honest oppinion... toyota just wants scion to stand out from the crowd.

also you increase the pulley. the 2:1 factor. if you decrease the size of the SC crank pulley you would run less then 1:1, then your engine would rotate faster then your SC can force air in.

khrys771

i was thinking today that it also might be developed to have the best fuel economy and performance. i seen my first xB and xA today and the window sticker had about 30 - 35 for the xB and 34 - 38 for the xA. so that is a possibility.

monsoon725

Turbo's dont HAVE to be intercooled and superchargers often ARE intercooled.


Adrian

erc

You would be happier with a Honda Civic Si than a Scion tC. They have hardly any torque, and you have to rev to an ungodly RPM range to get any power. It sounds like you're the "look at me" type who loves turning heads making all kinds of noise. Just get a BOV whistle and call it good.

arcyallen

Another reason a factory tuner might go with a supercharger over a turbo: how people drive them. If you want to have fun in the turbo, you'll want to get the RPMs up. And near redline, it'll be LOTS of fun. The supercharger won't give that same crack/adrenaline rush, so you'll be less likely to "beat" the engine. How people drive cars really effect the life of them. That sounds obvious, I know, but compare a Corvette with a 3000GT of a similar year. If you can find any. One will be still be running, one will be pretty rough. One was much more likely to be driven hard than the other.

The psychology of driving?

Icemanse2001

just a few things...

First of all... AHEM are we forgetting the Alltrac in toyota's turbo Barn :D

second if a person is truly worried about lag with a turbo, that is what a BOV is for, releasing pressure to decrease lag. at least thats the way i understand it, i may be wrong.

and finally Toyota has done a pretty good job matching the propper sized turbos to the right engines... The CT26, and The CT20B both produced gobs of power with an impressive lack of lag for the MR2 and the Alltrac's shared 3SGTE engine.

ok, ill shut up now

couper2

Cause superchargers are cheap, easy and safer.
TRD isn't part of toyota. It is a separate co.