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Old 11-20-2005, 08:18 PM   #1
DoctorNick
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Default Am I gearing myself too low?

This will be the new hybrid buildup for my swap.

V7 heads/cams
Ej257 shortblock
v7 ecu w/ ECUtek + utec

v7 JDM close ratio transmission + Grp N. 4.44 Fd.

With a stock 257, I can rev to about 7250 or so before you start to get hairy. Running a large turbo like a SZ49. I am kinda consirned that the stock torquey 257 might not be the best motor for such a short gearing setup. It seems like I would rev out 6th at around 150mph? maybe less? (how do I do the math on that?)

So, am I selling myself short with this setup by going with a motor that really can't rev out like my former complete v7 setup? Before i was revving to about 8100-8150.
Opinions?
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Old 11-20-2005, 09:40 PM   #2
Scoobie Steve
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Join Date: Sep 2000
Chapter/Region: Tri-State
Location: Bangor, PA
Vehicle:
1998 11.87@112mph
Subaru L Ver 6 STi Type R

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Horrible set up. Sell your trans to me .


If I ran an EJ257 I would have the cranks oil ports worked on and bump up oil pressure/flow. 8100 rpm should not be a problem.
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Old 11-20-2005, 10:20 PM   #3
zoophageousbeing
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I think you'll be fine. Right now I have a JDM six speed in my RS (with a 3.90 final drive). I still have the stock EJ251 in there right now, so I have to shift around 6250. I have absolutely no problem with the gearing being too short. With your higher redline and lower final drive, your gears will top out at almost the exact same speed as mine right now.

Here's where you will be at redline in each gear:

1st :32.1
2nd:49.1
3rd:66.2
4th:86.6
5th:109.8
6th:138.5

And here's where I am at redline:

1st: 31.5
2nd: 48.2
3rd: 65.0
4th: 85.0
5th: 107.8
6th: 135.9

You can use the web-based speed/RPM calculator in the Transmission FAQ sticky in the tranny forum to look up your speed in each gear. Your gears are: 3.636 2.375 1.761 1.346 1.062 0.842 I think you'll enjoy your set up very much. Of course, you'll have a lot more power so you'll pull through the gears a lot more quickly than I do, but I still don't think they'll be too short.
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Old 11-20-2005, 10:44 PM   #4
silentbob343
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Gearcalc
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Old 11-20-2005, 11:05 PM   #5
zoophageousbeing
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Or if you want to do the math yourself, the formula is:

MPH = (RPM x Tire diameter)/ (gear ratio x final drive x 336)
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Old 11-21-2005, 12:16 AM   #6
DoctorNick
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Thanks. Just what I needed
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Old 11-21-2005, 03:10 AM   #7
Billy
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Join Date: Apr 2000
Chapter/Region: E. Canada
Location: Toronto, ON
Vehicle:
1997 GF - silent ed.
12.677@107.87 untuned

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So if the tire size and gear ratio assumption is correct and this is correct...

1st :32.1
2nd:49.1
3rd:66.2
4th:86.6
5th:109.8
6th:138.5


... then you're looking at shifting 5 times before you hit the 1320 mark. Now on a road circuit, you'll always be in the right gear.
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Old 11-21-2005, 12:31 PM   #8
DoctorNick
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Yeah, I was running the QM in 5th before (trapping around 115).
Guess I'll be shifting even earlier now

This car is setup for the road circuit though. Hence why I stayed away from a 35r
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