Converter confusion: higher STR or steeper gears?
09-09-2004, 09:42 AM
#1
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Converter confusion: higher STR or steeper gears? Right now I have a SY3500 from Yank. STR is 1.61. 97% efficient. Yank touts this as one of the best converters they have as well as one of the best available ANYWHERE.
My question is... for as much daily around town driving as I do, wouldn't I be better off with a higher STR for all the stop and go? As the converter doesn't get locked too often except ont he highway.
OR... should I just go with a steeper gear? I have 3.42 now.
Going by Yanks converter selection chart, they show a SS3600 or SS3800 is the way I should go. They both have a 2.5 STR.
Yet they claim this SY3500 is the best all around.
What do you guys think? I know the lower STR is easier on the launch, but they say it carries the power longer. The STR is supposed to only really make a difference in the first 60' or so, and after that the converter efficiency is what puts the power to the wheels.
I'm only putting down 1.9 60' times with a 12.9 ET and 104.5mph. The SS converter has only 2% less efficiency, but it puts down 50% more torque on launch. With better 60' times, my ET's can only improve, right? Assuming I am putting down 325hp to the wheels, then the difference in the efficiency of the two converters is only 7hp (325/.97=335hp, 325/.95=342hp).
Seems to me the 7hp is not enough difference to make up for the 50% more torque hitting the tires at the line. And I can't see going to 3.73 gears making enough of a mechanical advantage to make up for the difference.
thoughts?
My question is... for as much daily around town driving as I do, wouldn't I be better off with a higher STR for all the stop and go? As the converter doesn't get locked too often except ont he highway.
OR... should I just go with a steeper gear? I have 3.42 now.
Going by Yanks converter selection chart, they show a SS3600 or SS3800 is the way I should go. They both have a 2.5 STR.
Yet they claim this SY3500 is the best all around.
What do you guys think? I know the lower STR is easier on the launch, but they say it carries the power longer. The STR is supposed to only really make a difference in the first 60' or so, and after that the converter efficiency is what puts the power to the wheels.
I'm only putting down 1.9 60' times with a 12.9 ET and 104.5mph. The SS converter has only 2% less efficiency, but it puts down 50% more torque on launch. With better 60' times, my ET's can only improve, right? Assuming I am putting down 325hp to the wheels, then the difference in the efficiency of the two converters is only 7hp (325/.97=335hp, 325/.95=342hp).
Seems to me the 7hp is not enough difference to make up for the 50% more torque hitting the tires at the line. And I can't see going to 3.73 gears making enough of a mechanical advantage to make up for the difference.
thoughts?
09-09-2004, 10:25 AM
#2
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One question. Can you leave the line at WOT without spinning the tires in the slightest?
If no, keep the converter you have now or get more traction. If yes, then you could use a harder hitting converter.
Keep the gears. Going with 3.73s isn't going to help enough to notice. You're just wasting gas mileage by doing that. If you need a harder hit, a higher STR is the way to get it.
If no, keep the converter you have now or get more traction. If yes, then you could use a harder hitting converter.
Keep the gears. Going with 3.73s isn't going to help enough to notice. You're just wasting gas mileage by doing that. If you need a harder hit, a higher STR is the way to get it.
09-09-2004, 10:30 AM
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no slip at all. the ET streets are doing their job. That's kinda what I thought too... more hit from the converter would make a LOT nicer launch... and the 2% loss in efficiency should make a nil difference at the big end.
09-09-2004, 01:19 PM
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I recently installed a SY3500 in my Z and have about 500 miles on the new combo. My immediate impression was that I had gone to small and should have gotten the SY4000. Under normal city driving the car starts pulling from about 2000 rpms. I am really surprised how streetable this converter is. I was also concerned that the STR was to low and that drivability would suffer. That's definitely not the case. Before installing the converter I had Chris R. reprogram the PCM for this converter. A while ago someone posted a video of a SSF3500. Either that converter is a lot looser or the driver has a much heavier foot. When my SY3500 unlocks the rpms do not swing nearly as much.
Your priority seems to be a converter that produces low ETs. In that case I would get the SS series. I was looking for a converter that would pull well from a roll and got the SY3500.
Your priority seems to be a converter that produces low ETs. In that case I would get the SS series. I was looking for a converter that would pull well from a roll and got the SY3500.