View Single Post
Old 01-15-2010, 10:14 AM   #17
OppositeLock
Scooby Specialist
 
Member#: 54060
Join Date: Feb 2004
Chapter/Region: Tri-State
Location: N Jersey
Vehicle:
Now: 16 FXT/04v8 207
Then:JRTuned fastest td04

Default

Quote:
Originally Posted by UFOpilot View Post
I disagree with people's method for determining shift points, completely. For one thing, I doubt you have any power past 5700 that's worth using, and you surely aren't getting "on top of the gear" by using the extra 1000 rpm. In fact you are over-running the prime band. Steve.804 seems to be the only person so far to notice this, and I agree completely. A friend of mine conveyed a story of how he missed 3rd and hit 5th instead, he hit the same time he did running it too high all the times before. There is a complex (though not overly complicated) method for determining your shift points, and you have to take the wheel torque into consideration. Not WTQ as defined by a dyno, but actual torque at the wheel for a given rpm. You then have to decide how much past prime will pay off given the cost of shift time. There is no question however that you could get better times out of the car.

Just one more opinion in a sea of too many.
He has a 2.0L car, the fall off isn't nearly as bad as the 2.5's.

Quote:
Originally Posted by poetic--playa View Post
i dont really understand this. what i am getting here is that if i was able to see my powerband (via dyno sheet) i would be able to plan my shift points, and in cases such as a stock td04, shifting as early as 5700-6k would be optimal? if i did that, wouldnt the next gear fall too short and i'd be waiting a bit for boost?
A dyno will not load the car the same as the road/track will. Running it in one gear from down low (loading it up) and ripping through the gears also put different loads on the car and change the curves. The best method for determining shift points is to hit the track alot and get comfortable enough to make changes from run to run.

Quote:
Originally Posted by xsnapshot View Post
A TD04 is bad, but its not that bad. On a 2.0L you shouldnt be shifting at 5700 RPM on the TD04.

Peak power usually occurs in the neighborhood of 5500 RPM and torque at 3500 RPM IIRC. But you don't want to shift at 5500. You would want to run it out another 700-800 RPM to take advantage of the area under that curve. Power over 6500 RPM drops off pretty quick usually (depending on your supporting mods, fuel, and tune) so no point in running out past that in 2nd/3rd but I would have to say its probably faster running 1st out to redline.

Keep in mind where you shift is determined by the shape of your powerband, which largely is effected by your tune. 20 psi should put out a lot of torque. Especially in cold temps at sea level. The higher your low/midrange torque values, the more advantageous it would be to short shift.
Agreed 5,700 is way too early on a 2.0. I've had best experiences taking 1st as far as possible (the gap to second is just ridiculous), 2nd almost to redline and then shifting the 3-4 a little shorter, maybe 6,300-6,500 (which means closer to 6K indicated on the tach). Also, flat shifting the 3-4 will bump your traps a bit, but doesn't seem to have as big an effect on time.

Quote:
Originally Posted by xsnapshot View Post
A trap speed of 99mph at sea level tells me there is something that's not quite right with the car. Even if your ET isnt the best, the trap speed usually doesn't change much. I would be hoping for significantly faster traps. No huge boost leaks/heatsoak/timing map problems? Running on 19" rims?
In cool weather he should be faster, but until he makes a clean run with good shifts, you don't really know as the car may trap 103 and look fine.

Quote:
Originally Posted by Steve.804 View Post
You also need to keep in mind your et is mostly made up in your first half of the 1/4 through your launch and how quickly and smoothly you can grab 2nd gear. So don't think the next time you head out and lower your rpm's you're going to be running 13's, you really need to practice driving it. You should however pick up some mph in trap speed. My previous 02 WRX using the canned stage 2 map from the v1 AP trapped 101.
Agreed, getting a good launch and keeping momentum/carrying g's during the 1-2 is most important. Just work on that 60 and 330 and the rest is easy. After you have your 60's and 330's down, you can focus on playing with your 3-4 shift point and see what works best. GL
* Registered users of the site do not see these ads.
OppositeLock is offline   Reply With Quote