Why Are Turbos Unwanted

[island911]

Originally posted by patkeefe
. . .. I would still imagine that compression regardless of the type of turbomachinery will still produce x amount of heat per specific volume of air compressed. . . .

I think that he's trying to say not all compressors produce heat equally. Sure, you can break-out the ideal gas law and see the isentropic work (no entropy) But thats massless-ropes and frictionless-pulley stuff

But, since I don't own a 930, I must simply not understand turbo.


What I don't understand, are those who say a 930 needs a 5-speed. (and a stereo volume knob that goes to 11 ?)

One slightly tweaked 930 I drove one day, tached-out at ~100mph . . .in 2^nd Gear!
. . .and the end of 2^nd gear came along faster than my SC (at only 60-something . .well, minus the roll-on lag)

That HUGE power-band . ..what's wrong with 4 ?


Problem with these turbos (imo) is; that power is terribly non-linear . . .and that non-linearity is not so repeatable. (it takes a lot to figure out how to "drive the boost")

[derickc]

Originally posted by nostatic
I see lots of turbo proponents talking about speed, etc, but I don't think any of them answered my question: is it appreciably harder to throttle steer a turbo v. na? I don't give a crap about how fast it is on the street or against an suv...what about on the track? I would love some more hp to have a better chance in the straights, but I don't want to lose any of the fine control in the corners. thoughts from those that know?

I've had an 87 carrera, an 88 930 with 350hp and a 78 930 with about 450hp. I've driven each on the track quite a bit.

When I sold the 87 and bought the 88 930, I thought I had made a HUGE mistake as the car felt heavier and much less "tossable." What I figured out is that the car is setup by Porsche with a LOT more understeer than the 911. I gave Weltmeister a couple hundred bucks and, viola, I had my tossable 911 back with 350hp...

With a properly setup suspension, the 930 will feel almost exactly like a 911. MY 78 only weighed about 2700lbs. It was MORE tossable than the 87 carrera.

Can you throttle steer? Yes, very easily. Is it more difficult? Yes. It is more difficult for a couple of reasons:
1) when you come off the throttle and out of the boost, you have to be very careful because you can go from 400 ft-lbs of torque to creating compression induced drag very easily. It happens fast and you have to learn to feather the throttle.
2) you have so much more power and are going a lot faster. Everything is more difficult when you are going faster.

In the end, the car behaves the same. It squats hard under acceleration and that backend really bites and puts the power down in an unbelievable fashion. Think of how often you are at full throttle on the track in a 911 and then imagine the car squatting just that much more and putting just that much more power down. Somehow, that rear just bites and launches you out of the turn, even with 200 extra horsepower.

It is faster, rawer, louder and more difficult, but then we all love 911s because of our desire to master the unique handling traits of that wonderful rear-engine that responds instantaneously to throttle inputs. You'd love a 930 for all the same reasons, only everything is magnified in an exponential manner. If you can drive a 911 fast, you are a very good driver. It rewards good habits and punishes bad ones. If you are fast in a 930, you are a really, really, really good driver.

Bottom line, I wouldn't recommend a 930 as a track car to anyone with less than instructor-level driving skills in a 911. It would be a very, very difficult car to learn to drive fast.

-dc

[RarlyL8]

With a 5spd or a closer ratio 4spd you can get to the power band quicker and keep shifting while in it. I have a 915 behind my 930 engine and just love it. There is no such thing as the wrong gear. They are all short enough to keep you in the power. Because 1st is so short you are instantly on boost. The "lag" in any gear is quickly eaten up by the shorter ratios. This would be less enjoyable with a real high HP 930 engine. You would run out of gears too quickly. The tranny gearing has to compliment the engine and car.

Now as for the original posted question, I agree with Jack and a few others. 930s are expensive to get into and expensive when they break. They are also 16-30 years old. Most are smart enough not to throw too much money at a bad investment even if it is a lot of fun.

[nostatic]

Originally posted by derickc


Bottom line, I wouldn't recommend a 930 as a track car to anyone with less than instructor-level driving skills in a 911. It would be a very, very difficult car to learn to drive fast.

-dc

that, sir, sounds like a challenge to me

Hmmm...something to add to the hopper. I'm getting flat in a lot more places on the track, but there is still time on the table with my measly 180hp. But last time out I was fast in the corners and slow in the straights, so I'm getting there. I suppose it might be cheaper to go 930 than to build the SCRS 3.0 MFI engine. But maybe not as cool

[mmastro]

The gentleman from Belgium:
"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."

I would not recommend a 930 for you if you just want to drive it in traffic. Driving ANY 911 in Los Angeles traffic is not my idea of fun...(early sunday mornings excluded ). THE TRACK, THE TRACK, THE TRACK!!!! Drive it at the track!!! I don't have a trailer, I drive it to the track and on the track and then home from the track...I live track day to track day now... I do drive my 930 to work just because I can't leave it alone! It's truly heroin for me...but when I do drive it, It "comes in handy" all the time! (and I do not prod SUV's...what a waste of time & fuel!)

Nostatic:
"I see lots of turbo proponents talking about speed, etc, but I don't think any of them answered my question: is it appreciably harder to throttle steer a turbo v. na? I don't give a crap about how fast it is on the street or against an suv...what about on the track? I would love some more hp to have a better chance in the straights, but I don't want to lose any of the fine control in the corners. thoughts from those that know?"

I'm just learning to throttle steer in my 77 930 3.0L Euro (my first 911) at Big Willow. I wasn't wide open in 8 or anything , but man i was keeping the wheel turned and modulating w/ the throttle to keep my speed through the turn approaching 9. I've been in only a few NA 911's at that track as a passenger only. Do you have experience in a 930 at Willow? It sounds like you would be an excellent candidate to report on the differences, if any, regarding ease of throttle steering, or not.

Cheers

[ianc]

Very interesting discussion. I've always wanted a 930, but don't really have the cash to pony up; prudence dictates it be diverted elsewhere. Maybe later.

Anyway, I was quite surprised to read that some of the early posters in the thread describe the turbo as a 'crude' means of power generation. I've always viewed the turbocharger as a quite sophisticated means of generating additional power from a given displacement.

Would anyone care to comment on the appellation 'crude'?

ianc

[mmastro]

derickc: "Bottom line, I wouldn't recommend a 930 as a track car to anyone with less than instructor-level driving skills in a 911. It would be a very, very difficult car to learn to drive fast."

Granted, my 930 isn't at 350-400 HP, but it's probably at 315-320HP/2750 LBS and shod with big rubber on each corner. It's my first 911. I'm learning (although slowly) to drive it fast at the track. I would say once it's aligned and set-up correctly, it's no more difficult to learn from that a NA 911?...Yes, I agree that a few more things have to be taken into consideration learning in a 930; on-coming boost , finesse on the throttle, etc., but it's been a blast learning to do this. And I have met soooo many people who have been supportive and offered their experience to make my learning experince more fun and enjoyable!
Now that's awesome!


Cheers,

[island911]

Originally posted by RarlyL8
With a 5spd or a closer ratio 4spd you can get to the power band quicker . . . Because 1st is so short you are instantly on boost. ....

Ah!
Thanks Dr. RarlyL8.

[island911]

Originally posted by ianc
. . . I was quite surprised to read that some of the early posters in the thread describe the turbo as a 'crude' means of power generation.. . .

Yeah, I wondered about that too. (Stephan wrote that turbos are crude. ...)

my take;

Originally posted by island911
Turbocharging is a sophisticated engine addition, which delivers heaps of power in a crude fashion.

Just think how much it would suck if your brakes decellerated the car in the same non-linear fashion as the turbo accelerates a 930.

People would NOT be happy.

[nostatic]

Originally posted by mmastro



I'm just learning to throttle steer in my 77 930 3.0L Euro (my first 911) at Big Willow. I wasn't wide open in 8 or anything , but man i was keeping the wheel turned and modulating w/ the throttle to keep my speed through the turn approaching 9. I've been in only a few NA 911's at that track as a passenger only. Do you have experience in a 930 at Willow? It sounds like you would be an excellent candidate to report on the differences, if any, regarding ease of throttle steering, or not.

Cheers

you offering to let me drive your 930 at Willow?

I've driven my na a fair amount at big track, but haven't been in a 930 there. However it would be fun to rectify that shortcoming. I'm interested to see what it does in 2, 4 and 5. And also how the boost affect you through 6 when you unweight.

[Navaros911]

Originally posted by skipdup
I never said it was only a daily driver.

It brings me pleasure to read the car is being put to good use

[widebody911]

I wish I was better off financially; the guy with the Ruf 930 cab wants to get rid of it and get, inexplicably - and I'm not making this up - a 914. Yes, I typed that correctly nine one four.

I'd take the 930, sell off the soft top, install a fiberglass hard top switch to fiberglass everything, build a cage, and make it my new track car.

[BlkBird]

My baby is in the shop - not an engine rebuild - just getting new tires, an alignment and a valve adjustment. Even sitting on jackstands with no wheels a 930 is still a menacing looking Porsche. Maybe it's the big flares? Maybe it's the 389 rwHP?

Who knows - but she is the perfect Porsche to me.

[Craig 930 RS]

A well-driven Turbo at 9/10th takes a lot more skill than a 9/10th driven N/A car --

[BlkBird]

Actually there is one expense that Turbo owners go through more often than NA owners - rear tires! Have you checked into the prices for 275 series Yokohama Sports? Ouch! And she'll spin them in 3rd gear!

New meaning to "pay to play".

[mmastro]

Mine won't spin the rears in 3rd...I still have the street gears in the 'box . Kumho victoracer 315 17's are pretty inexpensive at Tire Rack.

[Jeremy Cottrell]

Originally posted by nostatic
that's how you steer any 911...

Just watch the RUF Fazsination video. You will then be convinced without a shadow of a doubt that a turbo can be throttle steered. I would love a turbo, unfortunatly I would have to go to the police station and pick out my cell if I owned one.

[mmastro]

nostatic: "you offering to let me drive your 930 at Willow? "


Todd,
Um....Ah.....hummina, hummina, hummina.....

Nostatic: "I've driven my na a fair amount at big track, but haven't been in a 930 there. However it would be fun to rectify that shortcoming. I'm interested to see what it does in 2, 4 and 5. And also how the boost affect you through 6 when you unweight."


I'm just learning to use the middle of 2 (the banking). As I enter, I try to add more and more throttle to start steering, but I have to build up my courage a bit more... I'm working on the omega exit and trying to find my best line through there....I usually upshift (to 3rd) between the rear apex of 5 and 6. I stay on the gas over the right side of 6 and short shift to 4th at 7. I used to enter 8 at 85-90mph, but since I got the new rubber and the alignment during the last half hour of the day I was at 110 into 8 and THAT was a blast! I don't have the right gearing to blaze the straight, but it's fast enough for me at this stage.

Cheers,

[Emission]

Originally posted by derickc

Bottom line, I wouldn't recommend a 930 as a track car to anyone with less than instructor-level driving skills in a 911. It would be a very, very difficult car to learn to drive fast.

-dc

It's not THAT bad...

I started driving on the track (DE's) in 1998 in a BMW 328i. A couple years later, I upgraded to a 2001 BMW 330i. Once I had "mastered" that car ("B-Group" at BMWCCA schools) I sold it looking for a NA 911 (the BMW was pretty boring on the track). I found a 930 instead.

It is an entirely different driving experience in the 930 on the track. It takes more physical strength to toss the car, mental concentration to keep the engine in the rear, and it is a much more delicate dance around the curves. It has taken me three years, but now I run with the "A-Group" at the DE's I attend - in the 930 (I'm still not that fast - just really smooth).

Maybe in another three years, I'll be fast in the 930!

[S4drifter]

Emission, I have a similar experience. Went from an E36 M3 to an Audi S4 to the 930 on the track. I only have a couple of events in the 930 under my belt, but I am learning. I bought the 930 because I planned on having the car 10+ years and wanted a challenge. Well, I got what I wanted!

I am attending Skip barber's Advanced car control clinic next week to learn more about "rotating" the car. Hopefully It will help with my education. Fortunately for me, my home track is Watkins Glen, so I really get to wring the turbo out over a longer track.