Why not use a supercharger?

Keiller

Veteran Member
Joined
May 19, 2004
Location
Tennessee
TDI
2004Jetta GL Spice Red
It seems to me that a supercharger would give less trouble than a turbocharger. Anyone know why VW doesn't put a supercharger on the TDI?
 

Muggins

Veteran Member
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Jun 7, 2002
Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
Better question: Why not go without forced induction altogether since both are dodgy component systems that fail frequently and are weak links in the overall powertrain system.


So you lose a little power, but you gain a whole lot more reliability. Flame suit is on
 

Bob_Fout

Oil Wanker
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Sep 5, 2004
Location
Indiana
TDI
2003 Jetta - Alaska Green (sold) / 2015 GTI 2.0T
You'd get run over from behind all the time. Folks in Echos, Priuses and Insights would be passing and out-accelerating you, and we couldn't have that
 

cage

Top Post Dawg
Joined
Mar 25, 1999
Location
lakewood, ohio
Diesels have to have some sort of forced induction. Because of compression ignition and the always fully open throttle of a diesel there is nothing to excite or speed up ignition. While our TDI's do advance injection it isn't enough to give responsive acceleration. There are other reasons that I don't know enough about without looking up. It's been years since I've read about Diesel theory.
 

Muggins

Veteran Member
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Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
VW and Mercedes had non-turbo diesels and they were just fine. Turbo is completely non-essential. It's a cranky, troublesome, overly-expensive system that suffers frequent breakdown and requires costly repairs on an all-to-frequent basis.

We'd be better of without it from a service/repair standpoint. I'm not just talking of the turbine/compressor, but seals, actuator, hoses, clamps etc. that always seem to be causing problems.

Make it so it stands up as well as the motor, and I'm all for it. But it's not got the durability, longevity that TDIs are supposedly known for.
 

Powder Hound

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Under a Bridge, Crestview, FL, USA
TDI
'00 Golf 4dr White 5sp, '02 Jettachero 5sp, Wife's '03 NB Platinum Gray auto(!)
Turbo is completely non-essential. It's a cranky, troublesome, overly-expensive system that suffers frequent breakdown and requires costly repairs on an all-to-frequent basis.
I wouldn't own a diesel without a turbocharger. It is a simple device, and more reliable than the engine. What seems to be troublesome for a few people are a couple of control items.

I have had exactly zero problems with mine. Therefore, I disagree with your conclusions in as strong a manner as you declared them.
 

ProfBooty

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Jun 23, 2000
Location
Eagan, MN USA
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2000 Jetta, red
Turbos have come a LONG way in terms of reliabilty since their infancy. A lot of improvements and better materials have cured most of the things that gave them black eyes in the early days.

On another note - I've had a weird anomaly in the past on very cold days where the ECU has decided for whatever reason to completely disable the turbo. Let me tell you, that car cannot get out of its own way without the turbo. It's downright painful trying to accelerate away from an intersection. The '87 Toyota Tercel wagon I drove right after high school could absolutely smoke a TDI minus the 'T' any day. The couple time that happened it always corrected itself as the engine warmed up before I got to the freeway. I'm not sure the car would've even gone 60!
 

frugality

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Location
Spring Lake, Michigan
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none, 2016 GTI
Whether in a gas or a diesel car, turbos do one main thing: squeeze more power out of the same displacement. If you want comparable performance out of a normally-aspirated engine, you have to bump up displacement. That means reduced fuel economy and heavier engine.

Also, a normally-aspirated car isn't as 'tweakable' as a turbo car. Audi now has a 2.0L turbo gas engine that makes 200hp. If I read correctly, that engine is going into the VW GTI soon. No one is going to want a VR6 anymore. The turbo 4-banger will put out more power, will handle better due to less weight up front, and will be more readily chip tweakable.
 

Davin

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Location
L.A.
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2001 Golf GLS 5spd blk/blk
Better question: Why not go without forced induction altogether since both are dodgy component systems that fail frequently and are weak links in the overall powertrain system.
If you lived in europe you could go with this option. It's called SDI.

However, the SDI version of the venerable 90hp ALH engine has something like 60hp. I believe 0-60 time is 17 seconds.
 

dmtdi

Well-known member
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Aug 11, 2004
Location
Barrie Ontario Canada
I love my turbos, Havent touch the turbo in my V70 T5 240000klm 2.3lt 237 hp ,when you take it easy its not bad on gas. I hope I have the same luck with my TDI.
 

gern_blanston

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Location
PNW
TDI
Golf, '03, Silver
These little buggers are all about efficiency, and they've got 'em tuned pretty well, balancing back-pressure loss against the 'free energy' gain of the turbo filling the cylinders and giving more manifold pressure than ambient.
Turbo problems? Not very frequent in this day and age.
I spent a fair amount of my early flying career between 2 fixed-wastegate turbos on 2 'antique-technology' air-cooled, magneto-fired engines that looked a lot like 6-cylinder VW Bug engines, and never had any trouble with them, either. Different purpose, of course, as they were designed to produce sea-level power 9manifold pressure) up to the low flight levels, but we'd run 'em 1,600 hours between overhauls with very few problems.
Any mechanical device can bite the dust, but turbo problems are getting to be pretty rare.
 

OilBurnerBob

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Jul 2, 2000
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Left Coast, USA
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Jetta, 99.5, black on black
Some of the turbo problems, according to my neighbor who's a product development engineer for Garrett, is that after VW gave Garrett the specs for the turbo they wanted and Garrett designed it, VW specified a lower viscosity oil for the engine to reduce parasitic loses and the lower viscosity oil REDUCED the longevity of the turbo - putting more stress on the shaft and bearings.

Its still a nice piece of work and it holds up well if properly maintained.
 

MrMopar

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Mar 1, 2003
Location
Bloomington, IL
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none
Some of the turbo problems, according to my neighbor who's a product development engineer for Garrett, is that after VW gave Garrett the specs for the turbo they wanted and Garrett designed it, VW specified a lower viscosity oil for the engine to reduce parasitic loses and the lower viscosity oil REDUCED the longevity of the turbo - putting more stress on the shaft and bearings.
I think that in the future foil bearings might be implemented for vehicle turbochargers, completely eliminating the need for oil lubrication.
 

Joshinthecity

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Dec 5, 2004
TDI
05 Golf C'fortline 1.9 TDI 6-speed
Some of the turbo problems, according to my neighbor who's a product development engineer for Garrett, is that after VW gave Garrett the specs for the turbo they wanted and Garrett designed it, VW specified a lower viscosity oil for the engine to reduce parasitic loses and the lower viscosity oil REDUCED the longevity of the turbo - putting more stress on the shaft and bearings.

Its still a nice piece of work and it holds up well if properly maintained.
And by this Bob, you mean regular and timely oil changes?
j.
 

jck66

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Jan 4, 2001
Location
Greenwich, CT, USA
TDI
12 Passat SE / 14 BMW 535d
Whether in a gas or a diesel car, turbos do one main thing: squeeze more power out of the same displacement. If you want comparable performance out of a normally-aspirated engine, you have to bump up displacement. That means reduced fuel economy and heavier engine.
Yes, a turbo essentially turns your engine into a "variable displacement" engine. At 15 psi of boost, you are burning the fuel of a 3.8 liter engine at zero boost.
 

Muggins

Veteran Member
Joined
Jun 7, 2002
Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
Here is just one example of the gazillian problems we have the turbos. It's preposterous to say that this unit is just as reliable as the engine.

You could argue that technically it's not the turbo that's gone bad. That's irrevelvent. The turbo is non-functional due to a system component. Which happens again, and again, and again.

A crappy, troublesome system for which parts are not available on an individual basis.

http://forums.tdiclub.com/showflat.php?C...;gonew=1#UNREAD
 

nicklockard

Torque Dorque
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Aug 15, 2004
Location
Arizona
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SOLD 2010 Touareg Tdi w/factory Tow PCKG
A supercharger is less efficient overall than a turbocharger. It is always "on"; even if you had a variable nozzle supercharger, you'd still be wasting useable exhaust heat.
 

Joshinthecity

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05 Golf C'fortline 1.9 TDI 6-speed

nicklockard

Torque Dorque
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Location
Arizona
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SOLD 2010 Touareg Tdi w/factory Tow PCKG
It makes sense in that application: you're not (much) concerned with fuel economy, but the supercharger has no discernable lag, as it is either belt, gear, or chain driven from (usually) the crank.
 

gern_blanston

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Dec 3, 2002
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PNW
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Golf, '03, Silver
What problems have you had with your turbo, Muggins? The example that you quote IS a 170,000 mile car. I think that turbo may have lived a long and fruitful life.
 

maxforce

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Aug 17, 2003
Location
VA
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04 Golf, 04 Jetta, 84 300SD
Just thought I would throw this in, it is from another dicusion about the same thing. I had though that superchargers were a lot less efficient for everyday driving. You can find alot of reference to that. It seems to be fact. but if you do like the following poster suggest, would you not be adding a lot of pontential failers to a simple system just to get it efficient?

11 Jul 2000, 17:21
A example of the drive-train losses of a supercharger: the supercharger on a Jaguar XJR engine delivers about 120 HP at maximum. Since the XJR is about 80 HP stronger that the regular 4.0 litre Jag, it's quite obvious how much HP it costs to drive the supercharger.

I want to speculate on a possible application of supercharger however. I see a possible use in small cars like the Smart. You can fit a relatively small and low-power engine, which is very economical. Then if you add a supercharger with its own clutch (so it can be switched on and off, like the Mercedesses from the thirties), you can add power only when needed. You don't have to drive the supercharger unnecesarilly (like is city traffic, traffic jams and so on). If you combine this system with a continious variable transmission (CVT) and design the proper software, you can run the system fully automatic, and so that you achieve maximum performance and economy.
 

Muggins

Veteran Member
Joined
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Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
What problems have you had with your turbo, Muggins? The example that you quote IS a 170,000 mile car. I think that turbo may have lived a long and fruitful life.
I've had no problems -- and better not, at 40 k kms. However, let me ask you a question, g b. Would you be satisfied if your motor only lasted 170,000?

I don't think that's consistent with durability aspect which is allegedly synonymous with TDIs. Do you?
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
It is possible to switch superchargers on and off. In fact, most OEM applications do this in some manner. But it's STILL not as efficient as using a turbocharger. If you have a boost gauge, you'll note that the TDI engine runs under (more or less) boost ALL the time except at idle ... The capability of switching the supercharger on or off doesn't do a whole lot of good if it ends up being on most of the time anyway.

The Smart's engine uses a turbocharger. I know of no cars where economy was a priority, in which they used a supercharger. It simply isn't a very efficient way of getting the job done.

Now, having said that, I'll throw another tidbit out there for the masses to chew on. How many folks have heard of a Comprex pressure-wave supercharger? It uses the exhaust to pressurize the intake, as with a turbo, but it isn't a turbocharger. Most applications are belt-driven from the engine, as with a supercharger, but it does not use shaft power to do the compressing, it's only to provide a timing and sequencing function. Start researching ... I know what it is (and some of its faults, which I'll hang onto for a while ...)
 

gern_blanston

Veteran Member
Joined
Dec 3, 2002
Location
PNW
TDI
Golf, '03, Silver
Would you be satisfied if your motor only lasted 170,000?
Well, I drive 12,000 miles a year, so I guess I'd be happy with 170,000 miles. How long must an engine and all its peripherals last to be considered 'durable'? Not trying to be difficult, but what's reasonable life expectancy for an economy car?
 
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