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Old 04-21-2009, 09:41 PM   #1 (permalink)
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NOT FE friendly, Not all about the GTR. . .

As a matter of fact I have. I've been keeping tabs on this car and the Honda NSX since the NSX got discontinued.

The problem is the car is not. . .revolutionary in any way.


ok its got horses and its not a tank(it is by my standards but compared to a truck. . .)

Its got "technology."

It gets 3.3 0-60. Its fuel economy is combined rated for 18.

Its a 2009 that has only 254 hp/ton compared to a 1997 with 202 hp/ton naturally aspirated.

Not an engineering thing of beauty.

"It is complete not when nothing else can be added, but when nothing else can be taken away," is the definition of engineering that I subscribe to.

If it were truly a thing of beauty and horsepower and design. . .they would have scrapped the piston engine and went with a turboshaft engine. Could drastically reduce weight. 608 lbs for 480 horses. The engine produces .8 hp/lb. Relatively inefficient turboshafts drop 1.2/lb and high end models pump 1.4/lb. 729.6-851 horses for the same weight and considerably better FE, or you could keep the 480 horses with just 370 lbs instead of 608 and still even better FE.

Also the trans could be alot more simple with only 1-2 gears since the turboshafts can accomodate such high rpms.

So you can take that much more expensive much heavier sequential transmission and throw it away. The huge engine block, the turbos, the advanced differentials, the awd and virtually all of its complicated drive train components.

Convert all the pretty aero in the front to a ram-scoop for the engine. The turboshaft won't get off the line as fast, but as it approaches the end of the quarter mile you'll be doing more than 200 miles an hour, twice the speed of the GTR. Turbine driven engines increase power and torque as they increase speed because it increases their front end compression. Its the idea behind a Ram-jet engine.

sorry this is a discussion about if the GTR is all that or not.

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Old 04-21-2009, 11:47 PM   #2 (permalink)
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Can you run a turboshaft engine on unleaded automotive gas? Because I don't know too many people willing to own a car that requires Jet A.
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Old 04-22-2009, 12:15 PM   #3 (permalink)
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Quote:
Originally Posted by jesse.rizzo View Post
Can you run a turboshaft engine on unleaded automotive gas? Because I don't know too many people willing to own a car that requires Jet A.
actually that is one of the special perks of using a turbine engine. as long as the medium is heating and expanding(or really just has lots of heat energy) you can use it.

You can burn biodiesel, diesel, gasoline, a-fuel, 103, 101, 93, 91, 87, alcohol, propane, methane, SVO(filtered only) and wood/coal if you can grind it up fine enough to get it through and injecter. The US military tested this out on their Abrams A1 power pack in the event the vehicle was not able to be re-suppled what it would need to stay in the fight. If commercial gasoline is available it will burn it and there aren't really penalties for things like pre-ignition because the uel typically ignites about 50% through the combustion chamber so "pre-ignition"(igniting before the intended point in the cycle) radically increases the amount of power available.

The reason jets run A-fuel(usually 110 if I recall correctly with some other additives for turbine benefit brand depending) is because it gives the best p/w output(1.51 hp/lb while normal fuel will deliver something like 1.35-1.45 hp/lb).

Also Turbine engines have nowhere near as many moving pieces. A turbine has one shaft that connects(in jet engines its a little different) the radial compressor and the turbine blades, injectors, a spark plug thats used 1-5 times then switched off and thats it. A basic cylinder engine has a shaped crankshaft, 4 rods, 4 piston heads, 4 cylinders, minimum of 8 valves, 4 injectors, 4 spark plugs that ignite every 4rth rotation. The injectors on the turbine inject at steady flow while the cylinder has to inject in pulses. Less complicated/fewer moving pieces means fewer things can go wrong or break.
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Old 04-22-2009, 09:57 PM   #4 (permalink)
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Turbines do not like changing speeds. It generally takes quite a while (relatively speaking) for them to spool up or down to higher or lower power levels. They aren't a very good fit for an automotive application, generally.

The Mazda Wankel rotary gives some of the benefits of a turbine engine, and is more amenable to changing loads and speeds. But everyone thinks "Mazda" when they see a car with a rotary in it. Not such a good thing for Nissan.

I'd love to see one of the "halo cars" down near 2000 lbs in weight some time. I don't think it'll happen any time soon, though.

-soD
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Old 04-22-2009, 10:36 PM   #5 (permalink)
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Quote:
Originally Posted by some_other_dave View Post
Turbines do not like changing speeds. It generally takes quite a while (relatively speaking) for them to spool up or down to higher or lower power levels. They aren't a very good fit for an automotive application, generally.

The Mazda Wankel rotary gives some of the benefits of a turbine engine, and is more amenable to changing loads and speeds. But everyone thinks "Mazda" when they see a car with a rotary in it. Not such a good thing for Nissan.

I'd love to see one of the "halo cars" down near 2000 lbs in weight some time. I don't think it'll happen any time soon, though.

-soD
Agreed turbines take time to spool up, but once you get there they increase HP exponentially.

This is noisy so beware alright, I tried to defeat the autoembed feature so I could jump the video for you but the forum won't let me. I tried to jump it to 2:14
Given thats alot more power to weight than any car thats not just an engine and a steering wheel will have but thats a feat people pull to compare Veyrons, Enzos and McClarens to.

Also not to mention a car is more capable of housing a turboshaft engine than a car because if you increase the bike's length too much it becomes unwieldy so its difficult to cram the components in that space. A car. . .new story.

I would definitely sacrifice my ability to stay in the lead for the first 1.5 seconds of a 0-60, 1/4 pull for the ability to do 0-60 in 3 flat, the ability to do 200 in a 1/4 mile and the ability to crank out 250 mph over winning the first 1.5 seconds.

Last edited by theunchosen; 04-22-2009 at 10:44 PM.. Reason: edited URL to defeat auto-embedding
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Old 04-23-2009, 01:17 AM   #6 (permalink)
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Quote:
Originally Posted by some_other_dave View Post
Turbines do not like changing speeds. It generally takes quite a while (relatively speaking) for them to spool up or down to higher or lower power levels. They aren't a very good fit for an automotive application, generally.
Sounds like a properly sized (ie 20-30 HP) one could be good for an electric car as a built in range extender or on a pusher trailer. Electric only for around town and getting up to speed on the highway, then if it's too long of a trip for the batteries, fire up the turbine till it's time to get off the highway.

I wonder what sort of efficiency that would have compared to a similar sized (HP/torque) piston engine?

Sorry if this is taking this off-topic thread too far off-topic

Since you do claim this is "not FE friendly" to stay on topic I'll have it on the record that I agree with theunchosen:
Quote:
Originally Posted by theunchosen View Post
I would definitely sacrifice my ability to stay in the lead for the first 1.5 seconds of a 0-60, 1/4 pull for the ability to do 0-60 in 3 flat, the ability to do 200 in a 1/4 mile and the ability to crank out 250 mph over winning the first 1.5 seconds.
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Old 04-23-2009, 01:28 AM   #7 (permalink)
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Quote:
Originally Posted by Hugh Jim Bissel View Post
Sounds like a properly sized (ie 20-30 HP) one could be good for an electric car as a built in range extender or on a pusher trailer. Electric only for around town and getting up to speed on the highway, then if it's too long of a trip for the batteries, fire up the turbine till it's time to get off the highway.

I wonder what sort of efficiency that would have compared to a similar sized (HP/torque) piston engine?

Sorry if this is taking this off-topic thread too far off-topic

Since you do claim this is "not FE friendly" to stay on topic I'll have it on the record that I agree with theunchosen:
lol, as a rule of thumb I don't mind if it gets a little off-topic because its sometimes inconvenient to direct people away from something they are talking about somewhere else.

Actually the EV1 had a turbine in it. If the batteries drooped in charge the turbine kicked on to full operating power(I don't know what the optimum rate of that turbine was but each has one and away from that the efficiency is not pretty but on that its not bad and P-W wise its pretty darn good).

With the advancements in microturbines its kind of the way of the future for ranged EVs. Its nice to think one day we will be able to go 600 miles, but for the next 15-20 years it looks like micros might be the answer for hybrids(straight gas will just become more aero and GDI ultra-lean burn). Their P-W ratio makes them ideal since the motor doesn't run all the time and you want peak HP/(Fuel* weight) and turbines can do that for you since they can achieve 1.5 HP/lb relatively easily(high-high end diesels pump 1.101 hp/lb and at peak performance overtake turbines on power-fuel consumption, but that extra weight for the HP kills it.)

Basically my beef with the GTR is they are dumping an extravagently complex engine into a heavy chassis in the name of performance when in every metric an in house built 600 lb turboshaft would devour it or a 300 lb turboshaft would compete evenly up to 100mph and then it would devour it, with no technological advances in the drive train.
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Old 04-23-2009, 01:21 PM   #8 (permalink)
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Quote:
Originally Posted by theunchosen View Post
Basically my beef with the GTR is they are dumping an extravagently complex engine into a heavy chassis in the name of performance...
And charging you out the wazoo to maintain it. Just remembered seeing a link to this article in another forum.

edit: and don't expect to use that performance anywhere close to its fullest if you want to keep your warranty intact; And dont forget, big brother is watching you!

Last edited by Hugh Jim Bissel; 04-23-2009 at 01:37 PM.. Reason: more linkage
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Old 04-23-2009, 01:32 PM   #9 (permalink)
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Wow. . .

Thats all I have to say.

Thats at just 6,000 miles? after 100K miles you could have just bought half of another one. . .(33.3KUSD)

Thats even more expensive than service repairs for commercial helicopters and even large jet engine overhauls.

totally ridiculous lol.
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Old 04-23-2009, 01:39 PM   #10 (permalink)
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Quote:
Originally Posted by theunchosen View Post
Wow. . .

Thats all I have to say.

...

totally ridiculous lol.
Indeed! And I thought buying 5 quarts of Mobile 1 to change myself was expensive enough!

(ps, just edited previous post with more links of insanity!)

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