Why Are Turbos Unwanted

[valenciacarrera]

I would like to ask a newbie question. When you add turbo unit to 3.2 and 3.0, can 915 or G50 take the additional horsepower? Even with my current stock NA 3.2 carrrera engine, I've been told 915s are fragile.

[Jack Olsen]

Referring to the original post, the reason Turbos often take longer to sell in the used sports car marketplace is very simple: they cost more.

Sell a $10,000-$15,000 weekend car, and you've got a pretty big pool of buyers out there. Sell a $25,000-$35,000 one, and there are simply fewer guys with that much extra cash sitting in their checking accounts.

[derickc]

Originally posted by Formerly Steve Wilkinson
Opinion: turbos are a crude way to make power, and just as rear-wheel drive and rear/mid-engine are the gold standard, so is natural aspiration. Quicker, more linear and more predictable response. The people I know who have raced various turbocharged Porsche professionally admit that what you do, basically, is drive around the corner and then use the brute force to eat up the straights. Little finesse involved. As I said, purely opinion.

Stephan

That's how you drive a turbo if you don't know what you are doing. If you are having to "drive around" the corners, you are not in the proper RPM range which means one of several things:
1) you don't know what you are doing and are in the wrong gear or are going too slow
2) the gearing/cam/turbo profile of the car is not set correctly and the boost range is too narrow (a properly tuned turbo will be producing plenty of torque at 3K RPM, if you are below 3K RPM on the track, well, you don't know what you are doing).
3) you haven't setup the suspension properly. A stock 930 is tuned for even more understeer than a 911. A simple rear swaybar makes a HUGE difference in getting the car to turn.
4) you are going a lot faster than you would be in a 911 and are scared of the car.
5) there is more of a sensation of "driving around" the corners because there is such a dramatic difference in accleration. It's perception rather than reality.

[David]

I also think it comes down to money. When I bought my 930 I talked to the shop that worked on it and the painter that painted it. Both wanted to buy the car along with some guys at another shop I deal with, but it came down to who had cash in hand.

I really wonder how the hyper 930's are selling. It seems like it'd be really hard to sell a $40-$50K 25 year old car, but whoever bought it would have someone's $100K project.

They are a different animal than the 911. I like my 930, but I'd sure like to add a lightweight NA to my stable.

[patkeefe]

Yeah. Look at the Promotive kit. Nice, but $10k. Rebuild the 50,000 mile 3.0 first to accept it, that $15k for engine alone. For that kind of money, I'll go buy someones project 930 as David points out.

But for a small chunk of money, I could likely put a small output turbo on the 3.0 rebuild. I don't want 400HP, I'll be happy with 240.

[sammyg2]

Yes, you can just hang a turbcharger on an engine. Any engine. You just have to match the boost level and fuel delivery to the engine. That is the important part that most folks miss.

I've sucessfully converted 4 different engines from N/A to forced induction, including one stock 3.0 liter.
There is absolutely nothing that has to be done to a stock 3.0 to accept a turbo.
If you want to run higher boost levels than the engine (any engine) is set up for, you have to change the set up. No magic involved.

So, Why in the world would you have to rebuild a 50,000 mile 3 liter engine to accept a turbocharger?
I went to the promotive website. Unless I missed it, they don't even offer a turbocharger kit for the 3.0
If they do offer a system ofr the 3 liter, and if it is designed to run higher boost levels than the stock 3 liter can handle then the problem is with the system, not the engine.

The 915 is not fragile. They are plenty tough unless you are running mega power (400 hp or higher) range.

[BlkBird]

I really protest here! The 5 speed Turbos are ever bit as predictable as their NA cousins. With the proper modifications the boost comes on at lower rpm in a linear fashion, much the same as with turbo-less cars.

Turbo lag? Yes but tell me just how responsive the NA car is below 2500 rpm? All Porsches like to rev high and are recalcitrant before they get on cam. Its just that the difference between "on" and "off" is so much more noticable in Turbos.

Come to Atlanta and I will give you a demonstration.

[84CAB]

wow- lots of opinions... looks like its more a preference over power delivery and entry cost more than the $$ at rebuild time.

[350HP930]

Originally posted by 5axis
Grab a favorite beverage and sit down for a nice long read.
350's rebuild saga shows what is involved and also the HP junky while you are there disease. Also note the amount of time it has taken, with a moderate budget, expensive things need to be spread out a bit more.
Rebuilding My 930

david 89 turbo cab

Yup, I am the poster child for long running 930 projects.

If you had to hot rod a factory turbo car what would be better than a souped up 930 or 993TT?

[nostatic]

is throttle steering appreciably harder in a turbo? I know that when I'm in a long turn, I'm generally high in the rev range, but also making small throttle adjustments while trying to keep my hands still. Is there a big difference under those circumstances?

[HardDrive]

I am sure it has been said already, but turbos do not have a predictable power curve. My daily driver is a turbo. How much power you are going to have is very dependant on where you are in the RPM range, and it can catch you off guard in the corners.

But that being said......WHHHHOOOOOOOSSSSHHHHH....its a blast when the boost comes on

[Craig 930 RS]

Come take a drive with me in my 'new' 930.
I'll show you why there isn't a downside tp a properly prepared Turbo......

Just like my Varioram, keep it above 3k and the fun is there...instantly.

[afterburn 549]

In the future. We will only have ic engines with tubos..same hp less wt. they will be ceramic parts no radiator.
In the future and its here the turbo will have adj. blades, vanes -what ever you want to call them and no wast gate.They are self contained -no oil lines.
Its the wave catch it! all I need is more $$ as I have the envy

[350HP930]

Back when my car had just a little over 300 HP at the rear wheels driving it was an almost orgasmic experience.

I look forward to having around 500 RWHP in addition to being a little lighter in the rear.

[84CAB]

Craig- Funny you should post that, everyday I look at your for sale ad and an ad for a turbo and compare the two.. one of the same things they have in common is my lack of $$

[bigrubberjeep]

I have a feeling that anyone with a Turbo now, doesnt often say "Jeez I wish I didnt have a turbo"

[charlesbahn]

In the past I asked Protomotive about the 915 and the power put through it:
Was curious about ajackson's question about the 300 HP limit for a 915 tranny, so I asked Protomotive what their experience is -
"Depending on the year, they may be right.
The early 2.7 trannies can get bashed by a good 3.2 na engine.
The 1978-up 915's have a aluminum casing and a reinforced mainshaft and we commonly run mid 500's through them.
A strong Stage 3 with about 600hp will trash them though.
But it's not so much power that is killing them, but torque.
Many people are putting them in 930's and killing them with only 400hp, but at the 1.2 bar required from a 930 to get 400hp they're making nearly 500lbft of torque.
With a Carrera based system, at about 1.2 bar, we're making about 600hp due to the rpm capabilities.
So, with our turbosystem, with the high power, lower torque, we're able to run much more power through the 915's without hurting them.

[350HP930]

According to wayne's engine book the late model 930s had about 420 ft-lbs of torque at the crank, bone stock.

I think thats about the same amount of torque a ford lightning is pushing with a supercharged V8.

[valenciacarrera]

Thank you. I guess I don't have to baby my 915. It's going to be burn out at every traffic light from now on! Just kidding.

[yasir]

I currently own a 1991 C2 Turbo that probably has 310 rwhp and a 1994 Supra TT that has 415 rwhp and i am bored with both the cars
Future plans for next year are to go Single turbo ( $5000 ) on my Supra TT and that should give me atleast 500 rwhp and if i decide to upgrade the fuel system ( $ 1800 ) + possible clutch ( $ 1000 ) i should have atleast 600 rwhp on pump gas with 650 rwhp on 100 octane.
Well i will like to upgrade the Porsche power as well but it's not as easy and as cheap as the Supra.Any way i think by upgrading the fuel system,bigger turbo and bigger intercooler ( $ 5000 ) i should be able to make atleast 400 at the wheels
To summarize the whole thing,Power is very addicting once you experience 400 + rwhp/rwtq you just can't go back.
On the other hand it's very expensive and very hard to exploit power out of a normally aspirated car e,g the new Z06 with 500 rwhp with 3200 lbs would simply be unbeatable on the street/track but would also cost atleast high 60's to low 70's .