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Discussion Starter #1
One other reason i prefer turbos to superchargers. I can cruise around on 10 pounds of boost, and when i have to pull out into traffic and floor it, it's only 10 pounds, but saturday night at the illegals, i can wack the boost up to 20 pounds if necessary with my evc4.

with a supercharger, this is not possible, the only way i could see even trying to moderate supercharged boost, was if you were using a Rotrex Supercharger, which has a clutch like an a/c pump, and you could have different switches that were hooked up to different psi leveled Hobbs switches. even then it still would be kinda rigged, maybe a better solution would be an EBC hooked up to one Hobbs Switch, and to trick it, like a wastegate is tricked.

Still, none of the higher powered, better superchargers have an electric clutch built in them anyways.
 

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Discussion Starter #5
i was referring to - while in motion.

Originally posted by TEG:
You can change pulleys on an S/C to vary the boost...
CHIEM - no just because you have a supercharger does not mean you run cooler, as opposed to a turbo. it depends on intercooler size and efficiency, and if the turbo or supercharger is in it's efficiency. both heat the air when compressed about equally, everything else being the same.

[This message has been edited by IS300GTE (edited November 16, 2000).]
 

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Everything being the same, a turbo would heat the air much more since it uses hot exhaust gases to spool the turbo. Try touching your exhaust pipe if you don't know what I mean. The sizzling sound you'll hear is your skin cooking.

--k
 

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chiem is right - you do get some heat transfer from the exhaust manifold to the turbo compressor. I have seen lots of pics of turbocharged cars with the entire turbo glowing bright red. You don't see superchargers getting that hot.

But - yes, turbos can have an adjustable wastegate, and I have never heard of a "variable pulley" S/C (although it could be done if someone really cared).
 

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Discussion Starter #8
i agree, the exhaust does heat it some, but a supercharger is close to the exhaust or on top of the valve covers usually on most vehicles, and the same latent heat gets to it also.

if you moved it on the i manifold side on an inline motor, (that combo is not that common aside from 4 cylinders), and positioned it low, you might be able to achieve a 10-20 degree difference, but there is still heat in that area from the motor itself.


Originally posted by chiem:

Everything being the same, a turbo would heat the air much more since it uses hot exhaust gases to spool the turbo. Try touching your exhaust pipe if you don't know what I mean. The sizzling sound you'll hear is your skin cooking.

--k
 

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Latent heat the same in a turbo as a supercharger, now I know that you have no idea on the physics of heat transfers.

First in a turbo the turbine wheel is spun with exhaust gasses which heats up the whole assembly including the shaft, this shaft is the SAME shaft holds the compressor wheel, as everyone (well almost everyone) knows metal is an excellent conductor of heat.
Second the turbine housing that is subject to the extreme hot gasses is directly connected to the bearing housing assembly that also connects to the compressor housing, the turbine housing is made from cast steel, the bearing housing is made from cast steel and the compressor housing is made from cast aluminum, and again we all know that metal is an excellent conductor of heat. Typical temperatures of the turbo assembly after hard driving is around +500F.

On the flip side the supercharger is mounted on aluminum plates in FRONT of the engine and protected from the exhaust manifold by the heat shield on the manifold, and they are usually positioned over 12" away from the exhaust manifold with plenty of air seperating the supercharger assembly from the manifold, and we all know that air is a poor conductor of heat. Typical temperatures of the supercharger assembly usually reaches about 150F. Ex. Our 630RWHP GS400 intake temp was at only 109F after 10 back to back runs on the dyno when it was about 85F outside, and you could still touch the supercharger, it was just mildly hot to the touch, try that with any turbo and you will get third degree burns. Also there was an Mitcubishi Eclipse that day at the dyno that made about 640RWHP on the dyno running a Garrett T72 turbo and its intake temp was at 177F at the first run. I know what you are thinking, intercoolers, well the intercooler in the Eclipse was way bigger that our GS400 and more exposed.

So IS300GTE, please, please get familiar with both technologies before taking about which has what advantage over the other, superchargers by far have an "unfair" advantage over the turbos as far as heat is concerned. That is one of the main reasons why they are considered safer. Because too much heat and you get detonation and bam blown engine.

------------------
Muhammad I. Choudhury
Swift Racing Technologies
www.swift-racing.com
[email protected]
 

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Discussion Starter #10
"The quantity of heat absorbed or released by a substance undergoing a change of state, such as ice changing to water or water to steam" aka the combustion chamber, not the turbine.

latent heat - meaning the same heat that is hanging around under hood from the motor and radiator. the same heat that gives some cars a hard time starting in the summer, after they have been shut off, but only sitting for 5 minutes before being restarted. the same reason people have cold air intakes, to get away from the LATENT heat trapped under the hood.

you will not burn your hand on the compressor side, exhaust side definitely, but the compressor side doesn't get that hot, atleast not on either of my turbocharged cars.

as for intercoolers, you know as well as i do that a dyno is not a fair test for one, and no fan can simulate the amount of air that moves through it while actually driving the car on the street for a 3rd gear run, instead of driving it on the dyno for a 3rd gear run.


Originally posted by Swift Racing Technologies:
Latent heat the same in a turbo as a supercharger, now I know that you have no idea on the physics of heat transfers.

First in a turbo the turbine wheel is spun with exhaust gasses which heats up the whole assembly including the shaft, this shaft is the SAME shaft holds the compressor wheel, as everyone (well almost everyone) knows metal is an excellent conductor of heat.
Second the turbine housing that is subject to the extreme hot gasses is directly connected to the bearing housing assembly that also connects to the compressor housing, the turbine housing is made from cast steel, the bearing housing is made from cast steel and the compressor housing is made from cast aluminum, and again we all know that metal is an excellent conductor of heat. Typical temperatures of the turbo assembly after hard driving is around +500F.

On the flip side the supercharger is mounted on aluminum plates in FRONT of the engine and protected from the exhaust manifold by the heat shield on the manifold, and they are usually positioned over 12" away from the exhaust manifold with plenty of air seperating the supercharger assembly from the manifold, and we all know that air is a poor conductor of heat. Typical temperatures of the supercharger assembly usually reaches about 150F. Ex. Our 630RWHP GS400 intake temp was at only 109F after 10 back to back runs on the dyno when it was about 85F outside, and you could still touch the supercharger, it was just mildly hot to the touch, try that with any turbo and you will get third degree burns. Also there was an Mitcubishi Eclipse that day at the dyno that made about 640RWHP on the dyno running a Garrett T72 turbo and its intake temp was at 177F at the first run. I know what you are thinking, intercoolers, well the intercooler in the Eclipse was way bigger that our GS400 and more exposed.


 

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Discussion Starter #11
Originally posted by Swift Racing Technologies:
oh, and if you notice, only my first post was talking about the advantages of a turbo of a turbocharger, which is an ability to adjust boost levels from inside the car, even while moving.


So IS300GTE, please, please get familiar with both technologies before taking about which has what advantage over the other, superchargers by far have an "unfair" advantage over the turbos as far as heat is concerned. That is one of the main reasons why they are considered safer. Because too much heat and you get detonation and bam blown engine.
 

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OK here is a challenge:
Since you are in MD, why not get your IS300 turboed and meet us at MIR when they open next year, I think in April 8 (thats plenty of time), for a showdown in the Import Internationals. Turbo vs. Supercharger.

You will encounter two GS400s, an IS300 and a SC300 all supercharged and see what a supercharger can really do.

Now if you are trying to say the main advantage of trubos is controlling the boost from inside the car, well why would you want to turn it down in the first place, boost it up and keep it boosted.
 

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Originally posted by Swift Racing Technologies:
That is one of the main reasons why they are considered safer. Because too much heat and you get detonation and bam blown engine.
Ack. Muhammad, you made some really valid points, but you blew it here. The heat of the compressor itself does not affect detonation in any meaningful way. Ping and detonation come from fuel and timing issues due to increased boost...but I know you know that.

Also, to see an interesting supercharger (roots-type) application as far as heat transfer is concerned, check out the JR Supercharger (formerly Sebring) for the the Miata, it's mounted directly above the exhaust manifold...

Also, this is now a centrifugal supercharger (these are what you sell, right Muhammed?) kit available for the Miata that many people are anxiously awaiting - should start seeing installs at the beginning of the year.


------------------
Tony
'01 Spectra Blue
'94 Turbo Miata
 

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Discussion Starter #14
there is a mulitude of reasons why you would want to be able to adjust the boost inside the car.

1 air density (hot day/cold day high altitude/low altitude)
2 wheelspin
3 fuel mileage
4 to be easier on the vehicle when not racing
5 tuning (i tune every 3 psi)


i do admit that a supercharger has some advantages also ie: throttle response, slighty cooler intake temps, but a turbo also has it's advantages.
i guess it is a trade off....just like everything else in life.
as for the race, i am waiting for the 5 speed, but i will be happy to oblige after it's release.

Originally posted by Swift Racing Technologies:
OK here is a challenge:
Since you are in MD, why not get your IS300 turboed and meet us at MIR when they open next year, I think in April 8 (thats plenty of time), for a showdown in the Import Internationals. Turbo vs. Supercharger.

You will encounter two GS400s, an IS300 and a SC300 all supercharged and see what a supercharger can really do.

Now if you are trying to say the main advantage of trubos is controlling the boost from inside the car, well why would you want to turn it down in the first place, boost it up and keep it boosted.
 

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Yes - there are tradeoffs... Thats why we still see some cars with turbos and some with superchargers. The debate will never end. There is no "winner".
 

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Discussion Starter #16
agreed. i guess though, if i could use both on the same car, i would be in pretty good shape.
 

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Originally posted by Swift Racing Technologies:


Now if you are trying to say the main advantage of trubos is controlling the boost from inside the car, well why would you want to turn it down in the first place, boost it up and keep it boosted.
Because you can boost higher on race gas, but we all can't afford race gas all the time. Therefore, turn the boost down and you save some money.
 

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I wonder if you are all so infatuated with extracting power from a motor, why not buy a car that actually generates some power on its own?

The money it costs ($3500) to install a forced induction system alone bumps you into the 40,000's, and if you are really serious, you upgrade your heads and cams to maximize the benefits of the S/C or Turbocharger, that could be another $2000 or more. Then you have to start worrying about the drivetrain etc... Not to mention wheel/tire and suspension.

Why not buy an S4 and throw a chip in it, or a Vette or a Saleen Mustang, these cars stock will be as quick out of the box and will actually put the power on the road and keep you on it. The IS is a good car but would essentially need a ground up program to be a very fast and capable car.

Not that any of you would be caught dead in a fast car, it doesn't make sense to me to have a bazillion horsepower on a street car that will throw you in the weeds the minute you try to "use" it on your local offramp.

My .02

[From TEG:
1> Insurance rates are higher on cars with gobs of stock power, but (generally) don't change when you make some minor mods.
2> Yearly licensing fees (paid to the state) are based on vehicle purchase price.
3> Cars like M3/M5/S4 are in high demand and hard to get.
]


[This message has been edited by TEG (edited November 20, 2000).]
 

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Discussion Starter #19
well, everyone has a mustang, it is like having a civic. a fast IS300 is rare to not around yet. the IS also has a non turbo supra motor which hasalot of proven potential.
as for racing, if you can adjust the boost or if you keep it mild, you don't have to worry about spinning off the road, assumming whoever is a competent driver.
i personally like the look on peoples faces when i beat them unexpectadly, and all the cars you mentioned i have gotten that look from many times. those cars are faster naturally, so they expect to win, and it is fun to me to surprise them and put 10 cars on them in one gear.
 

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Maybe you aren't wearing your glasses, a turbo'd Is with moddest boost wouldn't even touch the three cars I mentioned. Even with heads and a cam you would be very hard pressed to beat a stock vette. You start gettin stupid with the boost you may start runnning down some decent cars, but only in a straight line.

My point was for the money, and assuming you actually are interested in a performance car, there are better ways to go. The IS 300 is by no means a limited production car, in the end you will see far fewer S4's, Saleens and Vettes. But to each his own, your comments have no direction.
 
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