What's better? Locked or Unlocked Converter?
03-12-2009, 08:50 PM
#4
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Allowing the TC to lock up under cruise conditions allows the tranny to run cooler and helps gas milliage some. Only reason I can think of to have a non-lock up TC is if the car is a track only, as it will never see conditions under whick it would lock up anyway. BUT...Many of the turbo 3.8l guys are running lock up on the strip with the TC locking up once the trans gets in high gear. Some claim increases of more than a 1/10.
RE'
RE'
03-12-2009, 09:12 PM
#5
This is a bit of a baited question as many factors come into play. I'll give you the best advise I can based on limited knowledge about your exact setup.
1. If you lock your converter during WOT it will significantly reduce the life of your trans or require a lot of hard parts to be changed if you make any kind of power.
2. Gearing becomes a huge issue. If you are running a 4.10 + gear and make ~ 500 RWHP FOR EXAMPLE and run a short tire (26") you will run out of gear with an unlocked converter @ 125 mph @ 7000 RPM'S (assuming a semi efficient 6% converter slip) If you lock the converter and reduce the slip to 0 - 1% you will gain ~ 1 mph at the same rpm for each % of slip reduction. ~ 130 - 131 MPH @ THE SAME 7000 RPM. If you don't make the power none of this matters.
2A. The opposite of # 2 would be if you run too low of a gear, say 3.42 with 400 RWHP you will never reach the meat of the power band and not have a need to lock the converter. You would benefit more from allowing the converter to "DO ITS JOB" allowing the motor to rev a little higher and continue to multiply torque which in return will get you into or at least closer to your power band.
3. N20 applications:
If you want the best of both worlds in a Nitrous car a good multi disc lock-up converter can be great. Example: My last F-Body was a 375ci iron motor with 2 N20 kits. I would run on the motor with the converter unlocked which would allow me to run a descent gear (3.70) and run a quick ET. On 1 N20 kit (SMALL 100 SHOT) I would also run unlocked (129 mph on a 28" tire @ 6800 rpm with about 10% converter slip) But when I would occasionally turn on the # 2 kit ( A BIT MORE THAN THE 1ST KIT
I had to lock the converter to avoid running out of gear.
Keep in mind though I had a $1200 converter and a $5000 Billet everything 4L80E trans and a monster cooler with a fan. Trans temps skyrocket when you lock the converter under WOT especially with big power.
FWIW - I played with locking the converter a lot at the track with just 1 kit turned on and I never saw more than .05 ET gain and typically about 1.25 mph. This was with ~ 550RWHP IN A 37OOLB CAMARO (.60 OVER LQ9 BLOCK, 4L80E, 9", FULL BMR REAR SUSPENSION ETC... IT WAS A BULLET PROOF TANK BUILT FOR STREET RACING)
Hope this helps. Call Greg @ FTI Converters he is the best in the business and will tell you the truth even if he doesn't have what you decide you want.
I've been running #'s for the last 2 weeks regarding what converter to run in my Z06, I'm doing a M6 to A4 conversion in 2 weeks and I make 570ish RWHP now on the engine.
1. If you lock your converter during WOT it will significantly reduce the life of your trans or require a lot of hard parts to be changed if you make any kind of power.
2. Gearing becomes a huge issue. If you are running a 4.10 + gear and make ~ 500 RWHP FOR EXAMPLE and run a short tire (26") you will run out of gear with an unlocked converter @ 125 mph @ 7000 RPM'S (assuming a semi efficient 6% converter slip) If you lock the converter and reduce the slip to 0 - 1% you will gain ~ 1 mph at the same rpm for each % of slip reduction. ~ 130 - 131 MPH @ THE SAME 7000 RPM. If you don't make the power none of this matters.
2A. The opposite of # 2 would be if you run too low of a gear, say 3.42 with 400 RWHP you will never reach the meat of the power band and not have a need to lock the converter. You would benefit more from allowing the converter to "DO ITS JOB" allowing the motor to rev a little higher and continue to multiply torque which in return will get you into or at least closer to your power band.
3. N20 applications:
If you want the best of both worlds in a Nitrous car a good multi disc lock-up converter can be great. Example: My last F-Body was a 375ci iron motor with 2 N20 kits. I would run on the motor with the converter unlocked which would allow me to run a descent gear (3.70) and run a quick ET. On 1 N20 kit (SMALL 100 SHOT) I would also run unlocked (129 mph on a 28" tire @ 6800 rpm with about 10% converter slip) But when I would occasionally turn on the # 2 kit ( A BIT MORE THAN THE 1ST KIT
I had to lock the converter to avoid running out of gear.Keep in mind though I had a $1200 converter and a $5000 Billet everything 4L80E trans and a monster cooler with a fan. Trans temps skyrocket when you lock the converter under WOT especially with big power.
FWIW - I played with locking the converter a lot at the track with just 1 kit turned on and I never saw more than .05 ET gain and typically about 1.25 mph. This was with ~ 550RWHP IN A 37OOLB CAMARO (.60 OVER LQ9 BLOCK, 4L80E, 9", FULL BMR REAR SUSPENSION ETC... IT WAS A BULLET PROOF TANK BUILT FOR STREET RACING)
Hope this helps. Call Greg @ FTI Converters he is the best in the business and will tell you the truth even if he doesn't have what you decide you want.
I've been running #'s for the last 2 weeks regarding what converter to run in my Z06, I'm doing a M6 to A4 conversion in 2 weeks and I make 570ish RWHP now on the engine.
03-13-2009, 10:49 AM
#7
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Now does the lockup apply to TH-400 trans and converters? I'm new to the TH-400 and I thought that I read that you can not get a lockup converter for that trans.
