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Kaptain
07-21-2008, 08:52 PM
New AJ-V8 engine

From the 2008 Goodwood Festival of Speed

http://www.ultimatecarpage.com/car/3788/Jaguar-XF-R.html

Jaguar XJ-V8 history (http://www.jagweb.com/aj6eng/v8_performance.php)

jagular
07-22-2008, 10:20 PM
enlarge the engine by 800 cc?

100 hp/litre seems like a lot until you realize it is supercharged. BMW and Audi get there with rpm. My 1997 SAAB Aero develops 97 hp per litre of supercharged power (by turbo). My chipped Audi S4 makes 114 hp/litre with twin turbos and an MTM chip.

However, it is torque that gives you acceleration. Even the Audi S4/S5 V8 produces less torque than the base Jaguar 4.2 V8.

Supercharged torque is even greater. Wonder what Jaguar extracts from the new 5.0 supercharged?

Gabriel
07-24-2008, 02:17 PM
Direct injection adds more to the pot also on the new 5.0.

When figuring the torque of a supercharged engine you have to add the displacment of the blower to the engine size. Then it seems to make sense.

Kaptain
07-27-2008, 01:36 PM
It is just a number. The aluminum Corvette C6 Z06 has a hand-built 7.0 liter LS7, but the engine weighs 71 pounds less than BMW's 5.0 liter V-10 (458 vs 529).

jagular
07-27-2008, 01:43 PM
if the same weight of car is involved then bhp/liter does have an effect. This is true whether you compare to engine weight or total vehicle weight.

The main effect of bhp/liter is the way the engine behaves. Most enthusiasts prefer high specific output engines.

It is a meaningful measure of engine efficiency also, within limits. If the engine is otherwise streetable and well behaved most of us would prefer the higher bhp/liter engine.

Finally, it is high specific torque per unit weight of the vehicle that driver's of street vehicles really benefit from. Lightweight engines producing big torque are fun to drive. Supercharging whether mechanical or turbo makes lightweight engines with big torque numbers that are a lot of fun to drive.

Kaptain
07-28-2008, 10:35 PM
The current Chevrolet Corvette Z06's hand-built LS7 has 505 hp from 7.0 liters yet gets 26 mpg on the highway and is the ONLY vehicle sold in the united states besides the base Corvette that has more than 400 hp with no gas guzzler tax.

Kaptain
07-28-2008, 11:12 PM
http://www.supercars.net/gallery/119513/1877/786669.jpg

http://www.supercars.net/gallery/119513/1877/786974.jpg

jagular
07-29-2008, 08:24 PM
The Corvette engine may be powerful in its way but it is ancient technology. As for fuel economy that has nothing to do with any supposed efficiency of the engine. The manual transmission has that goofy skip shift "feature" which invites actual real world drivers to use more throttle to ensure it doesn't do that. The automatic has a goofy fuel economy shift pattern which drives one crazy unless you put the boot when taking off.

The Corvette engine is not particularly efficient and is hopelessly inefficient at higher rpm due to the lack of multiple valves and poor control of valve timing due to the ohv cam in block configuration.

Don't get me wrong, the Corvette engines are possibly the best pushrod production engines ever made. But they are not great engines by any reasonable measure, they have low specific output (heck the last generation Mazda MX5 Miata had better specific output than the Corvete engine you mention and it certainly wasn't handbuilt) and they don't rev well.

The XF engine does rev well, gets pretty good fuel economy (the XF is a cool 1,000 lbs heavier than the Corvette, 25% more weight, and gets better economy in the real world) and produces pretty good specific power for such a civilized engine, almost the same as the fancy version of the Corvette engine actually and much more than the standard Corvette engine. It isn't hand built. Anyway, hand building is known to be inferior to robot assembly these days.

Gabriel
07-30-2008, 03:59 PM
420 hp and no gass guzzler tax

neilm
07-30-2008, 05:38 PM
Aren't all F1 cars hand built??????

jagular
07-30-2008, 10:31 PM
what is "hand built".

I understand that computer controlled assembly robots can torque engine components much more accurately and consistently than any human.

As for F1 bodywork, well, the molds are milled by CADCAM in styrofoam and the carbon fiber is laser cut controlled by computer. The bits may be laid up by hand but then the whole thing is vac bagged and autoclaved.

I mean Hawker Harrier Jump jets are hand laid up and cured with super duty hairdryers but the molds and carbon fiber bits are all made by computer.

neilm
07-31-2008, 02:36 PM
You were talking about engines.
The engines are hand built in F1
The only robot that goes near the cars is Michael Schumacher

Kaptain
07-31-2008, 08:06 PM
It revs to 7,000 rpm and is very compact. The skip-shift featured can be overcome. It weighs 71 pounds less than BMW's "f1-inspired" V-10. Many exotic sports cars have hand-built engines.

Hp/liter does NOT affect performance. It is a number. Weight, on the other hand, does affect performance.

Kaptain
07-31-2008, 08:07 PM
thanks

jagular
07-31-2008, 08:36 PM
If you skip the skip shift "feature" the fuel economy proves illusory.

Engine efficiency is directly related to volumetric efficiency, especially at part throttle. Smaller spark ignition engines are more efficient because they operate at wider throttle openings more of the time and are therefore more fuel efficient.

The larger the displacement the less the engine operates at wider throttle openings and so uses more fuel than it should.

The pumping losses from two valve heads and the friction and poor valve timing control of pushrod drivetrains are well known. They are flat just less efficient than overhead cam multi valve engines.

Bhp/liter is not significant by itself but it is an indication of relative efficiency for two engines performing the same function. I concede that inefficient engines can produce startling bhp/liter figures. F1 engines spring to mind. They have appalling fuel economy.

jagular
07-31-2008, 08:37 PM

Gabriel
08-25-2008, 09:30 AM
Here's the link to the XFR in Death Valley. The supercharger sounds wild. Nothing like what we have currently. Do you think this is a twin screw??? Or that 4 lobe eaton that the new Vette is using? I don't think a pre production intake would create this kind of sound.






http://autopark.blogspot.com/2008/08/jaguar-xf-r-spied-video.html

Moeshesa
08-26-2008, 09:50 AM
I want to see pics of the new XJ. Are you sure that thet have even designed one or are they just going to throw together a bloated XF?

Gabriel
08-26-2008, 12:31 PM
No it's much larger than a XF. The closest thing I've seen to from the side would be the upcoming Rapide but with the rear glass extending to the C piller. Much larger grill than the XF and a totally different interior.

Kaptain
09-16-2008, 05:29 PM
thanks for the video


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