4L80 Tune / Nitrous Converter
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Staging Lane
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From: East Liverpool, Ohio
4L80 Tune / Nitrous Converter Car is a heavy 2001 Trans am with a 402 that makes 525rwhp through a 9 in and a 4L80 with the converter locked. Both the tranny and nitrous converter are from very reputable companies and are high end parts but one or the other never seems to never be right. I have had the converter looked at a few times and by more than one place but the results seem the same. The converter seems to slip more than it should NA and gets worse with a 175 shot and is supposed to handle a 350-400 shot. I have make some minor changes to the tranny tune as far as when the converter locks and where it shifts but all other parameters are stock from the segment swap. Lookin for some help with the tuning to see if that may be the problem.
Last edited by mobileman; Jul 18, 2018 at 09:42 AM.
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Staging Lane
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From: East Liverpool, Ohio
Im not sure of the weight, but iron block, braced 9in, 10pt cage, all bmr suspension 4l80,, car still has the air, no weight savings. Car runs 11.10 @ 119 and 1.57 60ft. 175 shot runs 10.45 @ 126 1.45 60ft. Pulling 7 degrees just base tune, trying to figure out what the tranny/ converter is doing.
TECH Junkie
Joined: Dec 2012
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From: Iowa
What is the converter diameter? Can you share some more info on the specs of the converter.
Also, what are your typical trans temps when testing?
What is cooler line pressure and main line pressure (converter charge pressure is a derivative of cooler pressure and line pressure and can change the way the converter behaves...not super common with 4l80e stuff but it could be indicitive of an issue)
What type of fluid are you using?
Also, what are your typical trans temps when testing?
What is cooler line pressure and main line pressure (converter charge pressure is a derivative of cooler pressure and line pressure and can change the way the converter behaves...not super common with 4l80e stuff but it could be indicitive of an issue)
What type of fluid are you using?
I had a billet 245mm single disk nitrous converter from Circle D that was specd for a 402 ci ls and I put it in my turbo camaro and it seemed really loose as well to me but it stalled right at 3600 just like it was supposed to but wouldn't get efficient till 6500+rpm I never took it past 6800 but my ecu converter slip showed it was getting better and better. Maybe your bot spinning it high enough. I took it out as it didn't work right for my setup but it sounds like a similar situation to yours my car with me in it is almost 4000lbs.
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Staging Lane
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From: East Liverpool, Ohio
245 3c . Dextron/ Mercon fluid, Ill check the exact fluid when I get in the garage. Its a fluid Rossler reccommended. I do not know what temp the tranny is running at but it has a good size cooler and a custom Morrosso pan that holds 2 or 3 quarts extra. I have felt the tranny and cooler in the past and its definitely not getting hot. I was going to check pressures at the tranny now but wasnt sure what the pressires should be and how to change them if there not right. I wasnt sure if there was a setting I needed to check in the tune.
Last edited by mobileman; Jul 17, 2018 at 04:45 PM.
Thread Starter
Staging Lane
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From: East Liverpool, Ohio
Here is my tune. Its from last weekend when I tried switching to a 4.10 gear to see if it would help the problem and was also experimenting locking the converter in 2nd.
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Staging Lane
iTrader: (7)
Joined: Sep 2009
Posts: 52
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From: East Liverpool, Ohio
I had a billet 245mm single disk nitrous converter from Circle D that was specd for a 402 ci ls and I put it in my turbo camaro and it seemed really loose as well to me but it stalled right at 3600 just like it was supposed to but wouldn't get efficient till 6500+rpm I never took it past 6800 but my ecu converter slip showed it was getting better and better. Maybe your bot spinning it high enough. I took it out as it didn't work right for my setup but it sounds like a similar situation to yours my car with me in it is almost 4000lbs.
Last edited by mobileman; Jul 17, 2018 at 08:22 PM.
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Staging Lane
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From: East Liverpool, Ohio
3.73 and not locking the converter
https://photos.app.goo.gl/2mz67uQvX2gy9ddw5
4.10 and locking at the top of 2nd and keeping it locked. It spun the tires and I had to peddle it but still trapped 132.
https://photos.app.goo.gl/zLshznwSZJoKSFjJ8
https://photos.app.goo.gl/2mz67uQvX2gy9ddw5
4.10 and locking at the top of 2nd and keeping it locked. It spun the tires and I had to peddle it but still trapped 132.
https://photos.app.goo.gl/zLshznwSZJoKSFjJ8
Last edited by mobileman; Jul 18, 2018 at 08:32 AM.
TECH Junkie
Joined: Dec 2012
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From: Iowa
About the only 2 ways to change the converter behavior without physically altering the converter...is by converter charge pressure...or fluid type. Both usually only gain about 150-250 rpm on the stall speed which translates to a few percent on the big end.
If anyone else has an easy way to change converter behavior other than those two, please feel free to share. I may just not be thinking of one.
I'm not sure what you're thinking to change in the tune to get the converter to act differently
If anyone else has an easy way to change converter behavior other than those two, please feel free to share. I may just not be thinking of one.
I'm not sure what you're thinking to change in the tune to get the converter to act differently