Whats normal RPM for highway speeds
Whats normal RPM for highway speeds
Hey, I just had a question for 1st gen Q owners whats the normal RPM for highways speeds of 55mph and above?
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Jeff Williams
- Posts: 3394
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- Car: 1994 Infiniti Q45t
2000 Infiniti I30t
2004 Infiniti M45
71, 72, 73, 82 & 2000 Corvettes - Contact:
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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
With standard diameter tires inflated correctly:4th: 333 rpms per 10 mph= 2,000@60 mph * lock up on3rd: 480 rpms per 10 mph= 2,879@60 mph * lock up on
obviously different tires with different tread depth can vary these numbers by 4% as the real rolling size can vary by up to 1.5"
Work backwards from tire loaded rolling circumference [26" less sidewall compression [0.8"?]=~~ 78.5" or 790-810 revs per mile
obviously different tires with different tread depth can vary these numbers by 4% as the real rolling size can vary by up to 1.5"
Work backwards from tire loaded rolling circumference [26" less sidewall compression [0.8"?]=~~ 78.5" or 790-810 revs per mile
So the dealership I bought the Q from called me and said they'll reimburse me $1000 for misrepresenting the vehicle. Hopefully they'll be true to their word this time. My lawyer said I should have never agreed to it and have them pay for 100% of the repairs, but I thought it was fair. What do you guys think? I'm still kinda po'd but i think its fair.This is in reference to http://www.nissaninfiniticlub....40091
I got 2250@70mph last night---starting to snow in pittsburgh
I got 2250@70mph last night---starting to snow in pittsburgh
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- 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
Pretty much under 75 mph the ecu is attempting to maintain 14.7 AF...............it still tries all the way to 120 mph but errs on the rich side after the acceleration is complete.
If you get 24 mpg [use 2.5 gallons per hour] at 60 mph [2000 rpm] expect to use [4.083/3.538=1.154 or 15%] more at the same speed with the engine turning 2,308 rpm..........say 20.8 mpg.
The extra torque produced might make hill climbing easier and acceleration so it might not be quite as bad a physics dictate.Let's say 21-21.5-even 22 mpg depending on flatnesss of roads.
Based on my 19 mpg average let's use half the 15.4% or 8%.....15k/yr might use 60 more gallons per year ~~ $100-$120.
If you decide to do the swap get a JWT ecu [90-95] so that you can use the extra rpm rev limit [6900>7300] so that you can hold 2nd gear beyond 75-78 mph [to 84 mph] for a emergency pass.
Having a gear shift in the 55-85 mph range will lose you more than you gain from the 15.4% torque multiplication [0.2 seconds gained vs. 0.8 seconds lost in shift].
Every thing is a trade off somewhere.
If you get 24 mpg [use 2.5 gallons per hour] at 60 mph [2000 rpm] expect to use [4.083/3.538=1.154 or 15%] more at the same speed with the engine turning 2,308 rpm..........say 20.8 mpg.
The extra torque produced might make hill climbing easier and acceleration so it might not be quite as bad a physics dictate.Let's say 21-21.5-even 22 mpg depending on flatnesss of roads.
Based on my 19 mpg average let's use half the 15.4% or 8%.....15k/yr might use 60 more gallons per year ~~ $100-$120.
If you decide to do the swap get a JWT ecu [90-95] so that you can use the extra rpm rev limit [6900>7300] so that you can hold 2nd gear beyond 75-78 mph [to 84 mph] for a emergency pass.
Having a gear shift in the 55-85 mph range will lose you more than you gain from the 15.4% torque multiplication [0.2 seconds gained vs. 0.8 seconds lost in shift].
Every thing is a trade off somewhere.
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Jeff Williams
- Posts: 3394
- Joined: Fri Aug 02, 2002 4:17 am
- Car: 1994 Infiniti Q45t
2000 Infiniti I30t
2004 Infiniti M45
71, 72, 73, 82 & 2000 Corvettes - Contact:
Dennis, is the JWT ecu the same for 90 through 95? Of course, I am speaking of the standard (non-active) Q.Q45tech wrote:If you decide to do the swap get a JWT ecu [90-95] so that you can use the extra rpm rev limit [6900>7300] so that you can hold 2nd gear beyond 75-78 mph [to 84 mph] for a emergency pass.
Thanks.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- 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
JWT ecu only affects WOT or at least 8/10 th throttle up. Ideally one would supply their ecu as there were minor change in each subsequent year. Improvements in the other rpm bands, idle cruise, fine tuning for smoothness, etc.
Since the heads are nearly identical 90-95, other than some reshaping of the intake port, cams and valves identical in shape lift, etc.
The air flow and filling rates should be close, the injectors are the same 370cc/min, so the WOT injector open time should be the same and the plugs are identical so the ignition advance should be the same.
Not to say that each engine is exactly the same but since even JWT leaves some performance on the table for safety. The WOT performance regardless of ecu year should be within say 5%.....say 310-295 HP.........probably closer than that. [307-300].
The fuel injectors are spec at 2% but some may be dirty or out of spec thus the 5%. Different cylinders may get differing air flow from deposits on valves and just plenum imbalances, etc.Differing compression/leak down cylinder to cylinder, etc.
Since the heads are nearly identical 90-95, other than some reshaping of the intake port, cams and valves identical in shape lift, etc.
The air flow and filling rates should be close, the injectors are the same 370cc/min, so the WOT injector open time should be the same and the plugs are identical so the ignition advance should be the same.
Not to say that each engine is exactly the same but since even JWT leaves some performance on the table for safety. The WOT performance regardless of ecu year should be within say 5%.....say 310-295 HP.........probably closer than that. [307-300].
The fuel injectors are spec at 2% but some may be dirty or out of spec thus the 5%. Different cylinders may get differing air flow from deposits on valves and just plenum imbalances, etc.Differing compression/leak down cylinder to cylinder, etc.
Jesda- I have come to a resolution with the dealership now I have to come to a resolution with the vehicle I bought. I just could not find a car that matched my totalled car for the amount of money the insurance paid me. Let it be known the dealership (which I have never named on this site) was willing and did work with me to my satisfaction.
OK bck to the Q is it normal to fill a tank up and have 1/4 of it gone already in 1 days use (only going about 30 miles)?
OK bck to the Q is it normal to fill a tank up and have 1/4 of it gone already in 1 days use (only going about 30 miles)?
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elwesso
- Posts: 30810
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- Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
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Bad fuel pump.... ORDER ONE FROM JOE TOMORROW AND REPLACE AS SOON AS YOU RECIEVE IT........
The sender may be goofy too, but thats on the new pump anyway....... I think thats just the way with the system.... The gauge even says in the owners manual PROVIDES APPROXIMIATE FUEL LEVEL IN THE FUEL TANK..... Its very inaccurate once you get below 1/4 tank (1/4 full, 3/4 used), and when the low fuel light comes on you have about 4 gallons left!
The sender may be goofy too, but thats on the new pump anyway....... I think thats just the way with the system.... The gauge even says in the owners manual PROVIDES APPROXIMIATE FUEL LEVEL IN THE FUEL TANK..... Its very inaccurate once you get below 1/4 tank (1/4 full, 3/4 used), and when the low fuel light comes on you have about 4 gallons left!
I got a line on a junk yard here that does strictly imports and they have a pretty decent line of Q45 parts for all years right outside of Pittsburgh. John Wagner and Sons 800-472-2830 they have a 30 day return policy think I should go with them or go brand new? I used to get parts all the time from them and nothing failed on my Max.
I let my pump go, assuming the humming was something else. Ended up stranded. Then after installing the new pump, I ended up with a fried controller. It was luck that I got a used junkyard controller for free. Pump was $320. 1 hour installation labor was $55. Also replaced the fuel filter at the same time.
The towing and the cab fees just arent worth it. Plus, I could have saved $85 ordering from Joe.
-Jesda
The towing and the cab fees just arent worth it. Plus, I could have saved $85 ordering from Joe.
-Jesda
