Fx45

A forum for lovers of Infiniti's hot-rod crossover, the FX! In 2014, all FX models will be named Infiniti QX70, in line with Infiniti's new naming structure.
Mike Netzel
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Joined: Sun Apr 04, 2004 1:56 pm

Fx45

Postby Mike Netzel » Tue May 11, 2004 5:37 am

:help Hello,First post.Driving and enjoying my 2003 FX45.Questions include:What is available to improve the performance?Are headers, non-stock exhaust available?Engine mods which will drop it into the 5's in the zero to 60.What is available?I have changed the tires and wheels already.Most of what I am finding for performance enhancement is for the fx35.Thank you for your thoughts and experience!


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maxnix
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Car: 1995 Q45, 1995 Q45t, 2000 Q45

Postby maxnix » Tue May 11, 2004 5:37 am

Going to a smaller wheel diameter will definitely improve performance by reducing intial rotational inertia at the wheel.

The VK45DE is pretty well maxed-out in it's present state of tune. Intake and exhaust are fairly well optimized. There is an aftermarket superchaarger (last offered by Keuliyan), but I am dubious of its longetivity because I have seen two F50 so modified go through my dealer's lot with low miles.

Welcome to the board. The engineering forum mostly concerns theoretical discussions of engine and suspension performance. Might try your post in infiniti mechanic, infiniti general, or the specific FX35/45 forum.

Q45tech
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Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

Postby Q45tech » Tue May 11, 2004 5:37 am

Gear Ratios 1st 3.54:1 x 3.69= 13.063 correcting for 30" tires= 11.322nd 2.26:1 3rd 1.47:1 4th 1.00:1 5th 0.83:1 Final drive 3.69:1

Already tweeked to turn 7.5% more rpm in overdrive than is necessary........dropping down to 18" wheels ~~ 28" tall tires vs 30" might add 6% say 2% acceleration improvement with much lighter wheels. But fuel economy would drop by 6%

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AZhitman
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Car: 72 240Z RB25, 63 Bluebird RHD, 63 NL320, 67 WRL411, 67 SPL311, 68 510 SR, 73 240Z, 77 620 SR20, 89 Pao, 98 S14, 12 Titan CC 4x4.
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Postby AZhitman » Tue May 11, 2004 5:37 am

maxnix wrote:The VK45DE is pretty well maxed-out in it's present state of tune. Intake and exhaust are fairly well optimized.


Not in the FX they're not.

The FX has a detuned version of the 340 hp beast that powers the Q45 and thr M45. It is hobbled to 315 hp through the ECU program and exhaust design.

There's no reason you shouldn't (with a sufficient application of $) be able to return it to the 340+ hp mark, as there are no internal differences - all peripheral.

Mike Netzel
Posts: 5
Joined: Sun Apr 04, 2004 1:56 pm

Postby Mike Netzel » Tue May 11, 2004 5:37 am

:pface Mannix,Thanks for the info.That it is the detuned 340HP was not something I was aware of.I will chat in the forums you suggested.Just put some sharp Chrome 20's on it so changing tires and rims not something I would do for performance.I had not been able to find a supercharger for the 8, only the 6.Grateful for your input,Mike

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maxnix
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Car: 1995 Q45, 1995 Q45t, 2000 Q45

Postby maxnix » Tue May 11, 2004 5:37 am

I wonder how "detuned" it is, as in othere side by side tests of the VQ35DE, sometimes heavier, lower HP G35 coupes are faster than lighter, more powerful 350Z. I bet any concessions to HP are for a broader torque curve, perhaps exacerbated by more constrained intake and exhaust paths.

Only way to tell for sure is to compare part numbers, and examine part probiles if they are indeed different.

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AZhitman
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Car: 72 240Z RB25, 63 Bluebird RHD, 63 NL320, 67 WRL411, 67 SPL311, 68 510 SR, 73 240Z, 77 620 SR20, 89 Pao, 98 S14, 12 Titan CC 4x4.
Location: Surprise, Arizona
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Postby AZhitman » Tue May 11, 2004 5:37 am

Way ahead of ya - This was part of my research for the VH45DE header / catback project (which is halfway completed, BTW :))

Which has sort of spilled over into a VK header project.... :)

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AZhitman
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Posts: 69605
Joined: Mon Apr 29, 2002 2:04 am
Car: 72 240Z RB25, 63 Bluebird RHD, 63 NL320, 67 WRL411, 67 SPL311, 68 510 SR, 73 240Z, 77 620 SR20, 89 Pao, 98 S14, 12 Titan CC 4x4.
Location: Surprise, Arizona
Contact:

Postby AZhitman » Tue May 11, 2004 5:37 am

maxnix wrote:I wonder how "detuned" it is, as in othere side by side tests of the VQ35DE, sometimes heavier, lower HP G35 coupes are faster than lighter, more powerful 350Z.


p.s. Keep in mind we're talking about the VK here.


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