Turbo V Supercharger?
Discussion
lotusguy said: The data presented here is the published data from the kit makers themselves - Eaton and Vortec for the blowers and BEGI for the VATN and standard Turbo as reprinted in Vol. 17, Issue 1 (Jan 2001) of Sports Car International. I do not have the maiden name of the persons conducting the test nor their left shoe size, but I consider this data as valid as any out there. It wouldn't surprise me if you didn't, if for no other reason than they didn't invite you to personally observe each test
Brilliant stuff, Jim, may I congratulate you on your careful and accurate explainations, and on your patience!
John
Aren't superchargers, because of how they work, able to deliver higher boost pressure to the engine compared to a turbo without compromising reliability?
There are several different types of supercharger, but the most common (Roots) sort is based on a pump (i.e. the same basic design used to pump oil round the engine). They are not designed as compressors, and they're relatively inefficient at this. Turbos are much more efficient than Roots blowers. By efficient I mean they put less energy into the air when they compress it, hence you get lower charge temperatures and pressure for the same density and can boost it further before you get into detonation problems. Not all superchargers are like this though, some are true compressors and have compression efficiency as good as a turbo charger. I haven't come across any supercharger that beats a turbocharger in terms of compression efficiency.
Jon Gwynne said:
Interesting. Do you have any details on the tests? Who did them, who performed the mods, technical details on the devices used, displacement of the donor car engine, etc...
lotusguy said:
The data presented here is the published data from the kit makers themselves - Eaton and Vortec for the blowers and BEGI for the VATN and standard Turbo as reprinted in Vol. 17, Issue 1 (Jan 2001) of Sports Car International. I do not have the maiden name of the persons conducting the test nor their left shoe size, but I consider this data as valid as any out there. It wouldn't surprise me if you didn't, if for no other reason than they didn't invite you to personally observe each test.
You didn't need to bridle, I was just asking the source of the claims. ;->
Absolutely not, no way, no how! Superchargers, especially 'Roots' type blowers suffer from inefficiencies not known to turbo chargers due to the type of compressor (fixed-displacement). They will produce appreciable boost a little earlier, but are left behind by the much more linear power delivery of the centrifugal compressor of the turbo.
I understand the rootes blower isn't the best of all possible worlds. But having driven cars equipped with both turbochargers and rootes blowers, I prefer the latter and so do lots of folks. Incidentally, here's an interesting article from a couple of lads who seem to know their way around engines...
www.jagweb.com/aj6eng/supercharge.html
Seems like a Jag X(J/K)R supercharged their way would make well over 100bhp/liter and around 120lb/ft of torque/liter which is pretty good considering the size and refinement of that engine.
Then there's that "Performance Jaguar" place that coaxes 450bhp out of an XKR.
So, I'm not sure you aren't selling superchargers a bit short.
Are there any aftermarket turbo kits for the XK8? I'm not aware of any and a brief internet search didn't turn up any. If there are, It would be interesting to compare their performance to those of any aftermarket supercharger-based performance upgrades.
How about aftermarket turbo kits for the Aston Martin V8? With those ratty old Rootes blowers, AM were able to get 600bhp and 600lb/ft of torque out of their 5.3L V8 by the end of its life.
Again, not true, Rolls Royce and Bentley are turbochatged to name just a couple big cars. AMG also used to turbocharge a couple large displacement Merc engines. Granted, these don't have the 'manners' of a super and are therefore not used as often on luxo marques. Very few performance marques are supercharged though, and please don't present the XKR as a performance example, it would just be silly.
Why not? The XKR is a high-performance car. And a significant number of "performance" marques are supercharged. Jaguar, Aston Martin, Mercedes all offer supercharged models at the moment. Many other marques have done so over the years.
So, maybe it is time for you to get over this anti-supercharger bigotry and stop raining all over those who like their superchargers.
Put another way, I can't think of any comparison that would more severely tilt the results in favor of turbo-charging than the one you describe.
Also, what do you think about people like Gordon Murray's utter contempt for turbocharging as a way to increase engine power? It isn't as though McLaren lack experience in this field.
You keep referring to Gordon Murray and McLaren as if they were the 'Holy Grail' on this topic. May I remind you that McLaren is a chassis builder and has always had another produce their race engines, and, forgive me, but wasn't the F-1 powered by a BMW V-12 if I'm not mistaken?
The holy grail? Certainly not. But McLaren is a firm with impeccable engineering credentials and Murray is, I believe, their chief engineer. Regardless of his title, he is very outspoken on the subject.
Yes, they did eventually contract BMW to develop their engine. But BMW wasn't their first or only choice. They also approached other companies like Ferrari and (I believe) Porsche and Lotus. The specific reason they went with BMW was that the Bavarians were the only ones willing to design an engine to McLaren's power/weight specifications without using turbochargers. Murray is, as I have mentioned before, openly contemptuous of them.
Personally, I don't care. If someone wants to make or buy a turbocharged car, I say "go for it, have fun". But I'm curious why you're saying he's wrong and/or that you know better than he does.
On a related note, I looked up the Buick GNX in a reference book I have last night and it claims that McLaren developed the engine and that Buick only built 547 of them.
What's your point? Are you inferring that there is some reason, other than a limited production run, that the production was limited to this number?
I didn't infer anything. I was implying that because of the designer and limited production, that engine would have been able to produce more power than a bog-standard, mass-produced version of the same engine regardless of any forced induction and thus, I said to compare it to a mass-produced engine wasn't comparing "apples and apples".
>> Edited by JonGwynne on Wednesday 22 January 13:19
>> Edited by JonGwynne on Wednesday 22 January 13:20
funkihamsta said: Wow still raging.
MR2 mk1 supercharged. 1.6 engine.
Supra twin turbo 3.0
Bentley TurboR
Although very valid point about the marketing pitch of superchargers in prestige motors.
Edited to add Bentley turbo!
>> Edited by funkihamsta on Tuesday 21st January 17:39
As long as we're talking about small-displacement supercharged engines, Don't forget the Volkswagen Corrado and I think there are some aftermarket supercharger kits out there for the Lotus Elise
;->
>> Edited by JonGwynne on Wednesday 22 January 13:24
So, maybe it is time for you to get over this anti-supercharger bigotry and stop raining all over those who like their superchargers.
I don't think that anyone here is 'anti-supercharger'. Lotusguy is just trying to point out the inherent inefficiencies of that method of forced induction.
I too love the super charged motor from the XKR and the way it delivers the power but... I have no doubt that with the help of a couple of turbos it would be quite capable of knocking out over 1000bhp, nver mind a poxy 450.
>> Edited by randy on Wednesday 22 January 16:39
JonGwynne said:
The XKR is a high-performance car. And a significant number of "performance" marques are supercharged. Jaguar, Aston Martin, Mercedes all offer supercharged models at the moment. Many other marques have done so over the years.
As has already been explained to you, the fitment of superchargers to the above cars is not an engineering/performance decision, it is a MARKETING decision.
John
JonGwynne said:
Why not? The XKR is a high-performance car.
He He...Ok, ok... I thought you were serious about this post 'til this last bit.
Grand Tourer, certainly! Luxo Cruiser, perhaps. $96K worth of Chic, no doubt. But, at nearly two tons and automatic transmission exclusively, 'High Performance'?? Can you say Streeeeeetch???
Perhaps all the steroids pumped into it's Coventry Squirrel-box have leaked into the cockpit. I'd love to match up my Esprit with it, 'course your concern over direct comparisons would say that it wasn't fair that my lowly carburetted 4 cylinder 2.2 Ltr. blew the doors off your 3.9 Ltr. V-8!
Glad to see you've not lost your sense of humor in this whole thing. Thanks for the laugh...Happy Motoring...Jim '85TE
after my last visit to this post with flame bait i feel its time for another call.
this time without any vinegar.
having read throu this whole thread and still impressed buy lotusguy and his knowlage base(he still is a lotus lover and while that may not be to everyones taste, to each his own)
other than that it seems both sides have fair and valid aguments as to what form of forced induction is best.
personaly i have a lot of experience with turbo's and only a few encounters with superchargers.
all my turbo engines have been under 3 litres and all supercharged ones over 4litres.(only owned 1 engine between 3 and 4 litres and that was atmo,was also very poor.
so the only conclusion i can draw from this thread is that if you like superchargers then they are best.
if you like turbochargers then they are best.
if you actually drive your car and not measure its pub power.the quickest cars from a to b are atmo(this is infact a lie,the quickest car is the one with the best brakes.)i love what an atmo engine and good brakes can do for a car
this time without any vinegar.
having read throu this whole thread and still impressed buy lotusguy and his knowlage base(he still is a lotus lover and while that may not be to everyones taste, to each his own)
other than that it seems both sides have fair and valid aguments as to what form of forced induction is best.
personaly i have a lot of experience with turbo's and only a few encounters with superchargers.
all my turbo engines have been under 3 litres and all supercharged ones over 4litres.(only owned 1 engine between 3 and 4 litres and that was atmo,was also very poor.
so the only conclusion i can draw from this thread is that if you like superchargers then they are best.
if you like turbochargers then they are best.
if you actually drive your car and not measure its pub power.the quickest cars from a to b are atmo(this is infact a lie,the quickest car is the one with the best brakes.)i love what an atmo engine and good brakes can do for a car
Just as another talking point within this thread there is another type of forced induction which pound for bang is hard to match - Nitrous Oxide. Having tried both nitrous and Turbo i must say the Nitrous is quite fun if properly set up. IE correct CR correct air/fuel mix correct plugs etc etc. It has to be considered. But admittedly i found the draw back is the refilling of the bottle and change of plugs for "hard/soft" running. I believe the Luftwaffe used it on their fighters during the war! Or was that water methanol?
lotusguy said:
JonGwynne said:
Why not? The XKR is a high-performance car.
He He...Ok, ok... I thought you were serious about this post 'til this last bit.
Grand Tourer, certainly! Luxo Cruiser, perhaps. $96K worth of Chic, no doubt. But, at nearly two tons and automatic transmission exclusively, 'High Performance'?? Can you say Streeeeeetch???
Perhaps all the steroids pumped into it's Coventry Squirrel-box have leaked into the cockpit. I'd love to match up my Esprit with it, 'course your concern over direct comparisons would say that it wasn't fair that my lowly carburetted 4 cylinder 2.2 Ltr. blew the doors off your 3.9 Ltr. V-8! ...Jim '85TE
Sorry Jim, but I have to point out that despite the auto box and weight the XKR coupe will - just - out-acclerate all but the later SE and S4S Turbo Esprits and has a higher (limited) top speed. Not as quick along the bendy bits though.
randy said:
So, maybe it is time for you to get over this anti-supercharger bigotry and stop raining all over those who like their superchargers.
I don't think that anyone here is 'anti-supercharger'. Lotusguy is just trying to point out the inherent inefficiencies of that method of forced induction.
I too love the super charged motor from the XKR and the way it delivers the power but... I have no doubt that with the help of a couple of turbos it would be quite capable of knocking out over 1000bhp, nver mind a poxy 450.
>> Edited by randy on Wednesday 22 January 16:39
There's nothing wrong with supercharging as a concept. There are certainly some disadvantages to the rootes-type blower that most manufacturers use (though not bad enough to stop them using it) but those can be overcome by using different units.
Yeah, I have little doubt that you could get a turbocharged XK8 to pump out 1000bhp (maybe with the help of nitrous oxide injection) - for about 3 seconds until the engine ate itself.
Meanwhile, back on planet Earth, what would be the point? The Jag's chassis could never cope with that much power. Even if it could, the car would be unusable. I read an interesting interview with Peter Wheeler recently in which he explained why the roadgoing version of the Cerbera Speed-12 was never sold.
The guy who used to work on my Delorean had a customer who asked for "the most powerful Delorean in the world" and got one with a twin-supercharged small-block Buick V8 that made around 570bhp and still managed to fit comfortably in the DMC's rather cramped engine compartment. Unfortunately, I never got a chance to drive it. Hmmm, maybe I should ask him why he didn't use turbochargers. ;->
tuffer said:
mk1 said: I believe the Luftwaffe used it on their fighters during the war! Or was that water methanol?
Was also used by the Briish in the Spitfire (flying type) in WWII
And by the US airforce, which is how I believe it came to be used on cars, with ex-air force hot rodders who knew about it fitting it to their cars post WW2 for increased speeds on the salt flats etc.
johnelliott said:
JonGwynne said:
The XKR is a high-performance car. And a significant number of "performance" marques are supercharged. Jaguar, Aston Martin, Mercedes all offer supercharged models at the moment. Many other marques have done so over the years.
As has already been explained to you, the fitment of superchargers to the above cars is not an engineering/performance decision, it is a MARKETING decision.
John
Is that an assumption on your part or do you have specific experience with this?
v8guinness said:
How about aftermarket turbo kits for the Aston Martin V8? With those ratty old Rootes blowers, AM were able to get 600bhp and 600lb/ft of torque out of their 5.3L V8 by the end of its life.
Funny old thing but those Astons have around 900bhp before the Supercharger...
Naturally, they're looking for a way to try to drop a third of the engine's power...
Nice try.
grahambell said:
lotusguy said:
JonGwynne said:
Why not? The XKR is a high-performance car.
He He...Ok, ok... I thought you were serious about this post 'til this last bit.
Grand Tourer, certainly! Luxo Cruiser, perhaps. $96K worth of Chic, no doubt. But, at nearly two tons and automatic transmission exclusively, 'High Performance'?? Can you say Streeeeeetch???
Perhaps all the steroids pumped into it's Coventry Squirrel-box have leaked into the cockpit. I'd love to match up my Esprit with it, 'course your concern over direct comparisons would say that it wasn't fair that my lowly carburetted 4 cylinder 2.2 Ltr. blew the doors off your 3.9 Ltr. V-8! ...Jim '85TE
Sorry Jim, but I have to point out that despite the auto box and weight the XKR coupe will - just - out-acclerate all but the later SE and S4S Turbo Esprits and has a higher (limited) top speed. Not as quick along the bendy bits though.
Thanks. I didn't want to say it. He wouldn't like to hear it from me. ;->
But just to get a word in, I could also point out that the Jag's performance is more accessible to the majority of the driving public due to the TC/ABS and (especially) the auto box. The latter does wonders for making acceleration benchmarks consistent and repeatable by nearly anyone with a foot.
We'll give Jim the benefit of the doubt that he is both familiar and adept with his car and drives it as well as just about anyone but my grandmother in an XKR could out run him.
Lotus introduced fuel-injection a good way back. So when Jim says he has a pre-FI car, its probably a Giugiaro model and those topped out at around 200bhp if memory serves. Certainly an astounding output from a 2.2 liter 4-pot back in the day. But it would barely pass muster in a hot-hatch now and certainly has no business going up against an engine that produces twice as much power and lower down too.
p.s. Don't get me wrong, I adore Esprits in general and the S4S in particular but I don't pretend they're something they aren't. Next he'll be telling us his car seats four.
>> Edited by JonGwynne on Thursday 23 January 16:37
JonGwynne said:
johnelliott said:
JonGwynne said:
The XKR is a high-performance car. And a significant number of "performance" marques are supercharged. Jaguar, Aston Martin, Mercedes all offer supercharged models at the moment. Many other marques have done so over the years.
As has already been explained to you, the fitment of superchargers to the above cars is not an engineering/performance decision, it is a MARKETING decision.
John
Is that an assumption on your part or do you have specific experience with this?
It is an assumption on my part, but one that is based on observation. Other assumptions based on my personal observations are that(1) night will follow day, and that (2) you will not hear any argument that shows that turbochargers have major advantages over superchargers
John
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