Why Are Turbos Unwanted

[frencjas]

Personally, I like both NA and TC cars. I actually had more fun driving my 911 at the track when it was a narrow body 3.2 than now as a Turbo body with a 3.6 varioram with an extra 80 HP+/-. Sure, my lap times are a helluv alot faster now, but mildly less satisfying.

If I had a bunch of money when I got my 911, I probably would have purchased a a 930 instead due to the appeal of massive HP potential. Now that I can afford one, I really don't want one. I am quite satisfied with the power and balance of a NA lightweight 911.

My Audi, however, is turbocharged, and will soon be over 400 hp Even in its current state at 325+/- hp, there is no denying the satisfaction of turbo boost nailing you to your seat! It is truly addictive. As for Porsches, I have no desire for a 930 whatsoever. I am in the mood for a long hood 911 with a small displacement high reving flat 6!

[Emission]

Originally posted by 89911
Nobody in their right mind would prefer a 4 speed over a 5, or a 6 nowadays.

For the most part, yes... but it depends on the car. I love my 4-speed in my 930.

Late this afternoon, I got on a long freeway onramp and headed up to a nearly deserted freeway (the 23 at New LA Ave. for you locals).

I floored it through the gears to 120+ mph.

Just two shifts.

It didn't take long.

My car accelerates like a Boeing 757. Slow for the first 20 feet, then faster, and faster, and faster... then ZOOOOOOOOOOOOM!

I love my Turbo!

[Install425]

930 there is no substitute

[derickc]

Originally posted by patkeefe
Derickc:
I got a bit lost after the first paragraph. I was under the impression the only difference between a supercharger and turbocharger is the compressor drive mechanism, and that they both obey the laws of thermodynamics.
Pat

Sure they do. It comes down to adabiatic efficiency - how much do you heat the air when you compress it (ie - how hot is the boost?).

Here are the arguments for SuperChargers (addressing both types of superchargers - Centrifugal and Screw/Roots).

Argument 1 - A supercharger makes more boost at lower RPM and therefore has a broader, flatter torque curve.

The old roots style blowers (think of a 69 camaro with a hood scoop) are very inefficient. They move a LOT of air at very low RPMs, but they also make the air very HOT. This is the same thermodynamic law that applies to turbos - How much hotter is the air after you create boost? the answer - A whole lot hotter than a turbo. This is because the mechanism used to compress the air "beats" the air up a lot and makes it very hot. As the RPMs rise, they beat the air even more. A roots blower makes lots of torque at low RPMs and not much power at high RPMs, you could accomplish exactly the same thing with a smaller turbo, but why? Lots of low-end torque is good for an over the road trucker, but it's senseless in a sportscar.

A centrifugal SC doesn't make much low end boost or torque at all. It's actually a much steeper torque curve than a turbo because it produces boost as a square function of RPMs (whereas a turbo is flat after it gets spooled). Arguing that a CSC is better than a TC, is like arguing that kathy bates is sexier than angelina jolie. They are cheaper and simpler, but that's about it.

So, you can chose a roots blower and make lots of low-end torque with tons of extra heat and much less total horsepower than a turbo at the same level of boost, or you can buy a Centrifugal blower because it is cheap.

If you want the best of both (a broad torque cuve with lots of topend power), the best supercharger is a turbo.

[derickc]

Oops, I didn't finish Argument 2:
Argument 2: a centrifugal blower is just the "cold" side of a turbo and is just as efficient because it works the same way.

This is true. It does work the same way and at the same boost level they heat the air the same amount (unlike the roots, which heats the air a lot more). The problem is that it can only produce the same boost as a turbo at redline. Below that it is producing much less boost because it isn't spinning as fast as the turbo. It isn't spinning as fast because the RPM of the Centrifugal blower is directly related to the RPM of the engine, whereas the RPM of the turbo is related to exhaust velocity. Most TC engines produce enough exhaust velocity to spin the turbo fast enough to get full boost at 2500 to 3000 RPMs, after 3000RPMs the extra exhaust energy is "wasted" directly to the atmosphere via the wastegate (it goes "around" the turbo). You could tune the Centrifugal SC to produce full boost at 3k RPMs by using different internal gearing, however, it would then be producing a lot MORE boost at 4k, even more at 5k and even more at 6k. In other words, you would overboost and blow your engine at 4k RPM.

Make any sense?????

[JeremyD]

I love these conversations/threads/arguments. Typically people refer to Turbos in the element that they understand them. Old Turbos - the originals suffered from Lag. Were a handful to drive. New Turbos - those that have been upgraded to the K27 typically don't suffer from the same.

With the Turbo "import craze" going on right now - there are lots of turbocharging options out there, and they are getting much cheaper.

Unfortunately, Porsche flat six turbocharging is still very expensive. 10K WTF - some of these import guys are buying entire cars, turbocharging and getting twice the HP out of them and they still don;t have 10K invested in them. - Insane.

What scared me from purchasing a Turbo recently (and yes, my car was on the market) was all the stories and the insane amount of money some of these folks have spent on them. Also, all the Turbos I found had stories - long stories - like repaints, trashed, engines smoking, hack jobs to get more HP, that sort of thing. My car has lived a fairy tail in comparison...

For pure seat pinning action - it's tough to beat a turbo spooling up.

[derickc]

Originally posted by Jeremy964



Unfortunately, Porsche flat six turbocharging is still very expensive. 10K WTF - some of these import guys are buying entire cars, turbocharging and getting twice the HP out of them and they still don;t have 10K invested in them. - Insane.

That can be explained several ways:
1) limited market - there are only several thousand 930s in the US and there are several million honda civics.
2) value of the underlying engine - you want a well-engineered turbo system when you are talking $10k to $15k to replace your engine if you do something wrong. If you blow up a $1500 honda engine - who cares?
3) the addiction- the reason people spend so much more on turbos is because they get addicted to increasing the power. It's a function of fun and loss of wallet control more than actual requirements to spend lots of dollars.

In reality, in order to get 500hp out of ANY car, you are going to have to spend more than $20k. You could do it with a roots supercharger on a corvette, but one track session will toast your engine. How long do you think 7lbs of boost on top of a 10:1 C/R with no intercooling is going to last?? A properly engineered turbo for a corvette is like $25k.

The subies and mitsubishi's running 500hp are $30k plus engines (and they have a lot of problems with warped heads from trying to hold them on under all the boost).

The natural progression of the argument that a 911 is more fun than a 930 is like saying that a miata is more fun than a 911.

Truthfully, there are plenty of tight mountain roads in the US where you could have a lot more fun in a miata than in a 911. If you can't go fast enough to use the power, the extra power is worthless.

-dc

[wholberg]

Originally posted by 84CAB
Is it the higher entry cost of the turbos? More/higher maintenance? Higher engine rebuild cost? Turbo lag?

For me, Yes, Yes, No, No.

I have always been a Porsche owner on a budget, and my budget has never been large enough for a 930.

Maybe someday...

[Carl83911]

Originally posted by 84CAB
It seems that everybody is chasing speed here but the majority are attempting it with na cars. Is it the higher entry cost of the turbos? More/higher maintenance? Higher engine rebuild cost? Turbo lag? Just curious, it seems to always take longer to sell the 930s..Whats your opinion?

_______________

For those of us who can only afford a 20 year old car, Turbos in that era only had 4 speed. I think the 5 speed came in 88/89.

[Craig 930 RS]

Ask these guys if a Turbo is unwanted:

www.c2turbo.com
http://www.911turbo.com/

[Emission]

I "fell into" a turbo when I was actually looking for a NA Carrera. Glad I did, but I don't think I would have enjoyed a NA 911 any less.

In all honesty, I think a NA 911 is a better "overall" vehicle.

My turbo doesn't enjoy tight 15-25 mph windy roads - it prefers 45-90 mph sweepers. My turbo doesn't like stop-and-go traffic - it prefers 80-120 mph cruising (60 mph just plain sucks in a 930 - too slow for 4th gear). If mine wasn't a weekend/track car, I'd trade it for a NA.

I like the personality of my 930 (point-> gas-> hang on). It really is a machine in the most mechanical sense.

[JeremyD]

For any of those that come across any unwanted Turbos - shoot me a PM and I'll be happy to give them a loving home.

[fastpat]

Originally posted by Jeremy964
For any of those that come across any unwanted Turbos - shoot me a PM and I'll be happy to give them a loving home.

OK, here you go:

[930addict]

I'm also someone on a budget who happened to buy a 930 as my first Porsche. I really don't see the what the difference is in routine maintainance between a NA car and a turbo. I change the oil every 3k and give it a tune-up once a year - figure about $1k/year for maintainance, I have to pay a mechanic for everything as I'm not equipped to do the work myself. If a component of the turbo system were to break I can see the difference in repair costs, but so far my carhas been very reliable. I have 70k miles on my car and it's still running strong.

[Miguel Antonett]

I have had six different 911's including a 930. The 911's got recycled one way or another, BUT the 930 stays; it is 27 years old and still there is no substitute - 930's are GREAT CARS.

[widebody911]

I want a turbo, but I can't afford it.

I drove a Ruf 930 a while back. That car, with full interior, air conditioning, big sound system, etc easily out-pulls my obsessively lightened 3.6L 911. I was @ Tunderhill on Friday, this one guy with a very well modded turbo was wiping the track with me; he passed me going into turn 1 with a good 45mph or so speed difference. To get that sort of power in a N/A engine it would have to be about 9L (just a WAG)

[Emission]

Originally posted by widebody911
"...this one guy with a very well modded turbo was wiping the track with me..."

Great way of putting it!

[Navaros911]

First: I've never driven a 930.

It's probably a combination of money and usability...

Don't get me wrong, the 930 is usable in normal trafic... but let's face it, the 911 is allready one hell of a fast car for normal trafic and can only be used what it's built for a few times every drive. The potential of the 930 may only come in handy one time every few rides.

And this at a higher cost...

Paying 40k for a 20 year old car is A LOT.

If I had (loads of) money to spare I'd go for the 3.0 930... raw power and difficult to drive (I think).

[Craig 930 RS]

Usability?

Take it to the track....that's where my 930 is gonna spend a lot of time....

[ncoder]

I want my turbo!