Warning to me about twin turbos

[talskinyguy]

supercharger - noun:A blower or compressor, usually driven by the engine, for supplying air under high pressure to the cylinders of an internal-combustion engine

turbo - noun: A supercharger that uses an exhaust-driven turbine to maintain air-intake pressure especially in high-altitude aircraft.


I just thought I would point out that a turbo is a spacific kind of supercharger. Ill just leave you with a question, if superchargers are more effiecent then why does every big HP car use turbos, and why do semi's use turbos, and airplanes?

[Igovert500]

Originally Posted by Zeiss

Engine Response
The Turbocharger does not reach its maximum efficiency range until high speed and airflows are achieved later in the vehicle acceleration event. The latest Turbochargers with variable geometry housings and ceramic turbines still take four times as long as a positive displacement Supercharger to produce maximum boost.

The Supercharger is continuously driven at full boost speed for the given engine speed. This offers almost immediate boost response which takes approximately 0.4 secs to produce 50 KPA boost.

Efficiency
Turbocharger airflow delivery characteristics do not match the requirements of the internal combustion engine because of the volumetric efficiency versus speed difference. Turbochargers only display efficiency over a limited flow range. Turbo systems must be compromised to provide some low speed boost while matching high speed flow requirements. This usually requires wastegating which reduces maximum power.

The Supercharger exhibits an airflow delivery characteristics very close to the engine requirement. Thus, boost remains almost constant over the total speed range without wastegating or other compromising control systems.

Noise and Durability
With Turbos driven by exhaust gases turbine noise is nearly eliminated. Durability cycles are affected by the extreme temperatures that the turbine and housings are subjected to, leading to fatigue and inevitable failure.

Supercharger noise along with durability concerns have been the expressed reservations associated with automotive use. With improved designs and advanced materials noise levels have been reduced considerably with durability cycles proven well in excess that of Turbochargers.

Lubrication
Turbochargers are subjected to extreme temperatures and in "shut down" situation the oil remaining in the turbine bearing sections will reach coking (burning) temperatures. The carbon build up in the engines lubricating system will accelerate the internal wear of the engine and add to the rapid deterioration of the oil.

Superchargers can be lubricated by self contained systems which without the extreme heats experienced by Turbochargers will last for periods well in excess of the engine lubricants.

Aftercooling (Intercooling)
Turbochargers again are subject to extreme temperatures and discharge temperatures need lowering through aftercoolers if high performance levels approaching that of Superchargers are to be reached.

Superchargers do not require aftercooling as outlet temperatures rarely exceed 140 degrees C.

Driveability
Unlike a direct coupled Supercharger, performance is only enhanced in proportion to turbine speed. Therefore performance at low speed is limited and a distinct pause is encountered under acceleration known commonly as Turbo lag.

Performance is obtained without sacrificing the practical and constant rate in which this torque is delivered. Towing and Off Road-4-Wheel Driving can benefit greatly from the increased torque at low speeds.

Exhaust Emissions
Turbochargers can be tailored to meet emission levels at normal operating temperatures but suffer on cold starts. Contrary to the heat generated by a Turbo the exit gases are still low and on cold starts results in a longer catalytic light up time. This results in unacceptable levels of exhaust emissions at engine start up and legislation is slowly reducing the light up period available which will create problems for Turbochargers.

With legislation increasing pressure on automobile manufacturers to generate clean running engines Superchargers can easily be tailored to suit engine manufacturers emission designs.

Vehicle Modifications
A Turbo becomes an integral part of the exhaust system, therefore requiring major modification to the standard exhaust. This also is the single limiting factor dictating its position in relation to the inlet manifold. Additional pipe-work can be required to reach air cleaners and inlet manifolds when mounted on the opposite side of the engine. If an aftercooler is incorporated the potential piping requirements can become impractical. Turbochargers fitted to some vehicles needs to be insultated with a heat-shield lagging to protect under-bonnet-components from the extreme temperature generated. Brake master cylinders have been known to melt in a Turbocharged vehicle which raises other problems. Internal modifications are required in some cases such as compression modifications to accommodate the hot delivery air of the Turbocharger. Early opening of the exhaust valve will allow a high blow down pressure giving smaller engines more drive pressure from its exhaust but does sacrifice engine efficiency at cruise due to loss of full gas expansion.

A Supercharger need not change the physical configuration of a motor vehicle. A Supercharger is fitted where convenient by brackets and drive belt. Standard air cleaner and exhaust stay intact. No internal modifications to engines are required as the extra boost delivered is at a moderate temperature and which reduces the chance of detonation. No heat shielding is required for under-bonnet-components as again operating temperatures are low. No excessive plumbing required as Superchargers do not require aftercoolers and the unit can be mounted near the intake manifold requiring only a short discharge pipe.

Market Trends
Manufacturers have worked with or around the inherent problems of Turbocharging in the pursuit of performance, economy and emission controls. Now with other options available Turbocharging is becoming less important to many vehicle manufacturers.

Supercharging is becoming more widely accepted by original equipment manufacturers and different forms of Supercharging are now appearing on new vehicles.

Summary
In the past Turbocharging has been an accepted means of increasing engine performance. Even with its inherent problems it was the most cost effective method of forced induction. Now with improved manufacturing techniques and high volume production Superchargers can now not only offer better performance and packaging characteristics but can also now be price competitive.
http://www.prolexperformance.com/pro...percharger.asp

Good enough for ya?

Hmmm...engine response...we have AWD, who launches below 3k anyway? Plus that means we can drive off-boost when we want to conserve gas.

Efficiency, as was said, SCs are parasitic...turbos aren't.

Durability: Yeah, because I've never seen a broken supercharger....sure

Lubrication: Turbo Timer

Intercooling: Always a good idea, no matter what. Just because something may not be deemed 'necessary' hardly means it wont help

Drivability: Yeah, turbo lag sucks at low rpms in 6th gear...but that is the beauty of a clutch...you can shift. And I don't know about you, but I don't plan on doing too much towing/Off road driving in my 3000gt.

Exhaust Emissions: 1 word for cold starts...precats

Vehicle modifications: Hey luckily ours come with turbos stock. But of course if I do wish to upgrade, I have plenty of direct bolt-on options

Market Trends:

Summary:
prolexperformance doesn't sell turbos, they sell superchargers. As was said before, obviously they are a little biased. I don't know many Ford salesmen who recommend checking out Chevy's new line-up either.

Not to mention, your source is the same person who wrote this:
"Pro Lex Performance is proud to announce the introduction of the E-Shift knob for the IS and GS series vehicles. CNC machined from a solid block of pure billet aluminum. This knob is unique to the touch, not only does it feel good but smooth shift work is assisted by its moderate weight."

It's a freakin shift knob for crying out loud. Honestly, who the hell comes up with some of this shit

[Zeiss]

Finally some smart replies, thanks guys.

[talskinyguy]

I love the towing comment, cause we all know that nothing with a turbo can tow anything.....oh wait, what about a semi???

[Igovert500]

Originally Posted by Zeiss

Im sure the turbo boys on this site arent an unbiased source Hey though, since everyone has more posts then me I dont know anything so I will stop posting. Thats the stupidest thing ive ever heard.

Yeah, we are biased, obviously...but we aren't ignorant. You make a statement that one thing is better than another, and then you don't back it up with any RELEVANT unbiased proof. Yes we all know there are downsides to both...but if you want to argue this, then at least do it right.
And no, your post count doesn't relate to your knowledge, but it does relate to respect from the community and to credibility. We all know each other here, we don't know you. So when you come in as a stranger and disrespect a well-known member, everyone is apt to get defensive.
If you want to leave, that is your own perogative. But if you stay, you may want to organize your argument a little differently and you may want to consider future personal comments.

[Dreamspawn]

Sry to jump in here but this is when i think everybody should look at this buetiful article http://www.automotiveforums.com/vbul...d.php?t=201348

[Zeiss]

nice, thanks

[fantomdave]

Well back to the original question. It all depends on when you want to put in money. If you buy a N/A 3s and then supercharge it, you pay a little less for the car and then you have to dump money into that for all the nessasary work. I am not sure what it takes to maintain a SC 3s only an N/A and it isn't much as long as you take care of it. On the other hand if you buy the TT and leave it as it is you will pay more for the car but probably a lot less than putting the work into the other one. Maintaining it though can be more expensive, not because it is an unreliable car but because AWD, the turbo's, AWS, and all the other complicated parts on the TT make it very hard to work on and very expensive to replace. Although it all comes back to taking care of the car. If I were you I would go with the TT. I'm not going to get into turbo's vs. super's because as you can see we can argue that point all day but I would prefer things like AWD and wouldn't mind putting in a little more money to fix those when the time comes. Thats my two cents.

[Zeiss]

Thanks for the advice dave. I picked one out, a 94 RT manual.