05-02-2005, 02:28 PM
Iím finding that with general driving my shift points are around 3 grand, RPMís drops to about 2 grand and I maintain my speed, 35-45, very easy in 3rd or 4th. .
When Iím jumping on it I move the shift point to just above 4000, RPMís drop to around 3000 and the motor has plenty of torque to pull to the next shift point. The Toyota speck sheet stated max torque @ 3800 rpm so that is one of the reasons Iím shifting @ 4000. Are any of you finding different/better ways of running this motor and transmission combo?
05-02-2005, 02:56 PM
just cause max tourque is 3800 doesnt mean it fall off after that, the point of a good shift is to be making the same power as when u shift, if u shift too early u are out fo the power band and making less power on the shift. if u shift too late(cant cause of rev limiter) u are makin more power than when u shifted. if that is easy to understand.
MidKnight X RunneR
05-02-2005, 05:24 PM
if you're just crusing i would shift whenever. i normally drive at about 50-60 in 6th gear on most streets. just depends on how you drive. best shift point for power i have found is just shy of 5400rpms, but thats just my opinion.
05-03-2005, 06:13 AM
i actually was shifting right at 5400 before now i shift around 5000 and it feels alot better going from 2nd to 3rd it will even chirp the tires
05-05-2005, 12:49 PM
when driving hard i shift at between 5k-5.2k, i feel a big loss in power at 5.2k, so i see no point in shifting any later then 5.2.
07-28-2005, 11:03 PM
At what speeds/rpms have you racers been shifting at to get a stocker to do maximum speeds/minimum times?
07-28-2005, 11:25 PM
First gear goes by quick; rev limiter is set at about 5500+, so I shift at about 5300-5400. Same for second and third. The one thing I have noticed is that for maximum power, you don't want to lift up on the throttle all the way--maybe half way. It takes some practice, but a half power-shift for first (Use the clutch, only lift half off the throttle), then a full on power shift from second and third seems to work, but only if there is enough grip. Yes, perhaps a bit hard on the clutch, but the clutch in the XR seems to take it way better then the tires.
07-29-2005, 07:08 AM
It seems to me that the 1st gear shift point can be high due to the high gear ratio but in order to fully utilize the amount of torque that these stroker engines put out, the shift point in subsequent gears might produce better speeds in the 1/4 mile if you find a shift point somewhere in the 4500 to 5000 rpm range rather than redlining every shift.
Reason I ask this is because with a slightly modified 440 engine in a Dodge Charger, I found that speed and ETs improved when I shifted at much lower speeds that redline. Just curious to know if anyone has tried to find optimum shift points with the stock configuration on the X-Runners.
07-29-2005, 07:46 AM
Forgot to mention that I call these engines strokers because when I was reviewing the specs on the upcoming Avalons, I noticed that the HP rating was higher but that the engine has VVTli which features a variable lift as well as a variable valve opening feature. The redline and HP ratings are higher because the stroke is about 10 or 11 mm shorter.
I know that the shorter stroke engines can rev higher and so I am interested in putting in a shorter stroke crank. The Avalon crankshaft may be a good swap on top of which the compression ratio would decrease. With the decrease in compression ratio, I could more fully utilize added boost pressures and greatly increase the power output of this engine. But by how much will the compression ratio decrease is the question on this part.
Also are the main and rod journals the same size.
My approach to building a race car out of this truck is not based on adding on easy aftermarket enhancements but rather a true HP increase in the engine in combination with NOS at the low end and Turbo for the high end.
I believe I can optimize the power output of this engine at the end of 4 or 5 years after the VVTli Engines come out and am interested in letting Toyota iron out the kinks, then getting one of these to rebuild and tweak.
Then of course the whole drivetrain ratio changes need to be made to maximize HP to the ground.
So in accordance with this effort, I am studying the available engine, trans, and rearend combos that are readily available as stock units.
I believe there are several rear end ratios available but I'd like to swap out entire rear ends when I go to the strip. That way I can use the stock unit on the street for fuel and driveability and use the strip unit when I want to race. Now that brings up the question of how wide the tire spacings and spring mounts are between the various rear end models.
I continue to read about how everyone is adding on enhancement parts but would like to hear from those of you that are doing some serious replacements. It's difficult to get the measurements of the various engines, trans, and rearend units. Add to that the the tire/wheel combos and fender/chassis/lift clearances and I see that this hobby will last me another 5 to 10 years before completion at least.
My goal is to lower this vehicle another 2 to 4 inches, dump the skirts, put on wide tires for road course racing and a small front/wide back set for the strip with two different transmission and rear end setups to match.
Accordingly I'm in the market for heavy duty engine blocks, pistons, rods, cranks, and heads. NOS and turbo combo setups are being studied at this point but will be in the market once I can figure out the optimum compression ratio to balance fuel economy with good race capability. Maybe even a V8 may be in the future if the engine will fit and it performs better. There's a lot of room under that hood!
Imagine pulling up to what looks like a stock four banger Tacoma with your Vette and getting blown away a 1/4 mile later. That's what I call SWEET !!