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Edmunds Test Drive - Nissan GT-R

Old May 12, 2008 | 01:08 PM
  #46  
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Originally Posted by SSbaby
No you wouldn't unless you want to blow up your engine. The Z06, with hypereutectic pistons doesn't take too well to boosting.

Just saving you an engine... in case you have too much cash on the side!
I was more or less joking. However, it can handle 6 lbs on stock internals which is about 600-650 rwhp. The compression ratio is what keeps boost so low and causes the pistons to fail. 11.1 ratio.
Old May 12, 2008 | 03:49 PM
  #47  
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Originally Posted by SSbaby
No you wouldn't unless you want to blow up your engine. The Z06, with hypereutectic pistons doesn't take too well to boosting.

Just saving you an engine... in case you have too much cash on the side!
I didn't even post that But since we are talking about it, what about a Z06 with a GT-R motor

Originally Posted by soul strife
I was more or less joking. However, it can handle 6 lbs on stock internals which is about 600-650 rwhp. The compression ratio is what keeps boost so low and causes the pistons to fail. 11.1 ratio.
Old May 12, 2008 | 06:37 PM
  #48  
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Originally Posted by Bob Cosby
And I thought Camaro was a pony car (much like the Mustang), and vehicles like the Challenger, Charger, & GTO were muscle cars? Heck, I'd even include the G8 GT in that category.
All pony cars are muscle cars. It's a subcategory.
Old May 12, 2008 | 07:12 PM
  #49  
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LOL.

Uncle.
Old May 12, 2008 | 08:19 PM
  #50  
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Originally Posted by Eric Bryant
Modern turbos also don't run pig-rich like they had to 20 years ago. Engine management has come a long ways since then, and we now have the wonders of closed-loop operation at high loads and throttle openings via wide-band O2 sensors.

Just like with diesels, people have some misconceptions about turbochargers that just won't go away that are based on decades-old observations.

No misconceptions here. Turbos must run higher AFRs and turbos also breathe harder and better. No surprises there.

I don't need to state that for a given amount of air drawn into the engine, a specific ratio of fuel must be supplied. In the case of turbos, the more power they make (usually more than atmos) the more fuel they need to keep the engine from detonating.

As a ROUGH guide:

AFRs @ WOT

amto: 12.5-13.0
turbo: 10.5-11.0

Therefore, turbos do use more fuel unless you drive them sedately.
Old May 12, 2008 | 08:48 PM
  #51  
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Originally Posted by SSbaby
No misconceptions here. Turbos must run higher AFRs and turbos also breathe harder and better. No surprises there.
Who says that they have to run richer? Point me to a rule, please

I don't need to state that for a given amount of air drawn into the engine, a specific ratio of fuel must be supplied. In the case of turbos, the more power they make (usually more than atmos) the more fuel they need to keep the engine from detonating.
You're overly generalizing, especially for an engine that was designed to be turbocharged.

Therefore, turbos do use more fuel unless you drive them sedately.
I disagree - at least if we're talking about a properly-designed stock engine (which is a way different situation than hanging your own turbo kit on a modified engine and then trying to fool a stock ECM into keeping everything happy... or at least alive). I think you'd be somewhat surprised if you saw the AFR of, say, the LNF at WOT.

And regardless, WOT fueling targets have minimal-to-no effect on EPA mileage estimates (and generally don't factor heavily into real-world driving unless someone is actively trying to lose their license).
Old May 12, 2008 | 09:23 PM
  #52  
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I'd say it's common to see stock, boosted vehicles blowing black smoke at WOT, from generous "factory" fuel ratio's...they want to play it way safe.
But that's one area most tuners adress first, with programming or chips on older models, ofcourse in addition to that they add timing retarders and maybe alcohol injection to help keep detenation at bay.
But driven at anything under WOT, even with low boost levels, they run surprisingly clean and easy on gas.
Old May 12, 2008 | 10:34 PM
  #53  
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Originally Posted by Eric Bryant
Engine management has come a long ways since then, and we now have the wonders of closed-loop operation at high loads and throttle openings via wide-band O2 sensors.
My Grand National runs closed-loop at WOT.

It's not running a stock chip, but it's nothing fancy -- just a reflash for 93 octane.
Old May 12, 2008 | 11:37 PM
  #54  
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Originally Posted by Eric Bryant
Who says that they have to run richer? Point me to a rule, please



You're overly generalizing, especially for an engine that was designed to be turbocharged.



I disagree - at least if we're talking about a properly-designed stock engine (which is a way different situation than hanging your own turbo kit on a modified engine and then trying to fool a stock ECM into keeping everything happy... or at least alive). I think you'd be somewhat surprised if you saw the AFR of, say, the LNF at WOT.

And regardless, WOT fueling targets have minimal-to-no effect on EPA mileage estimates (and generally don't factor heavily into real-world driving unless someone is actively trying to lose their license).
Eric, in your statement earlier... you touched on "closed loop". There is no way I would run Closed Loop under WOT. Rule book or no rule book.

When it comes to performance, nobody *****-foots around in Closed Loop. Irrelevant point, therefore.

So what AFRs would you run boosted at WOT?
Old May 13, 2008 | 06:00 AM
  #55  
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Originally Posted by SSbaby
Eric, in your statement earlier... you touched on "closed loop". There is no way I would run Closed Loop under WOT. Rule book or no rule book.
You won't (and neither will I, since I don't own anything with a wide-band O2 and a PCM that can use it). But what about the factory? Modern ECU hardware has come a long ways in the past few years.

When it comes to performance, nobody *****-foots around in Closed Loop. Irrelevant point, therefore.
Irrelevant to the task of tuning a 5-10 year old vehicle, yes; but very relevant to contemporary vehicles. Don't make the mistake of viewing everything from your (relatively narrow) frame of reference.

So what AFRs would you run boosted at WOT?
What's the application? If I'm trying to boost a relatively ancient engine with port injection, narrowband O2 (meaning that I have to run open-loop), a traditional wastegate, and poor control over spark advance, then it's going to be the same pig-rich fueling that you're surely thinking of. But that's not the way that the world works anymore.
Old May 13, 2008 | 06:52 AM
  #56  
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Originally Posted by Eric Bryant

Irrelevant to the task of tuning a 5-10 year old vehicle, yes; but very relevant to contemporary vehicles. Don't make the mistake of viewing everything from your (relatively narrow) frame of reference.
Thanks for the complement.

We're talking GTR vs Z06 here, not ancient chariots. There would not be one point at the 'Ring where either a GTR or Z06 will be in closed loop. These cars are meant to be driven and under such scenarios, they would both chew down the fuel but the turbos generally have the bigger appetite irrespective of their capacity disadvantage. Turbos simply blow harder. Simple.

Which (non-race) cars these days run WO2 sensors? I'm not aware of any. Therefore, the only way to protect these engines would be to run them at consistent AFRs with charge temps cool enough to endure the heat stresses i.e. by suppyling more fuel. The ratios I provided are not far from being truly accurate in most cases (happy to be proven wrong).

The only way the turbo engines could be made to run reliably leaner (that I can think of) would be by adopting direct injection.

Anyway, sorry folks for digressing.

Last edited by SSbaby; May 13, 2008 at 07:08 AM.
Old May 13, 2008 | 07:02 AM
  #57  
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Hey, SSbaby, see post #55.
Old May 13, 2008 | 07:32 AM
  #58  
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Originally Posted by JakeRobb
Hey, SSbaby, see post #55.
Yes and I ignored it for good reason.
Old May 13, 2008 | 07:51 AM
  #59  
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Originally Posted by SSbaby
Which (non-race) cars these days run WO2 sensors? I'm not aware of any.
The simple fact that you're not aware of any pretty much says everything. One example of a production LNF with a wideband O2 is the GM LNF:



There are several others. The first wideband O2 in a production vehicle was the Civic VX back in '95(?), so it's not exactly new or exotic technology.

Therefore, the only way to protect these engines would be to run them at consistent AFRs with charge temps cool enough to endure the heat stresses i.e. by suppyling more fuel. The ratios I provided are not far from being truly accurate in most cases (happy to be proven wrong).
There are several ways to decrease the charge temp - better intercooling, improved intake manifold design, less boost, more efficient turbocharging. You also can manage detonation by improving the combustion chamber efficiency.

My Impala runs a compression ratio of 11.7:1 on pump gas. 15 years ago, that'd be impossible - but the combination of EFI, decent (for the time) combustion-chamber design, aluminum heads, and reverse-flow cooling makes it possible. And now you've got production vehicles running north of 12:1!

Technology changes. Make sure that your frame of reference can, too.

The only way the turbo engines could be made to run reliably leaner (that I can think of) would be by adopting direct injection.
There are several others (see above).

Once again - stop approaching this from the standpoint of throwing a big turbo on a vehicle that was never designed around forced induction, and stop thinking that the ability to do some minimal calibration on a 5-year-old hacked ECU using third-party software constitutes any sort of understanding on state-of-the-art engine management. That narrows your thinking too much.

I'm done.

Last edited by Eric Bryant; May 13, 2008 at 07:55 AM.
Old May 13, 2008 | 08:38 AM
  #60  
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I haven't seen that car in silver, the one I saw was red in some video. Silver really looks pretty sharp, but I don't think I would ever buy one. Performance is all there, but I will always stick to American Muscle

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