C3 upgrade: LS7 + 4L85E / 4L80E or 4L70E
11-26-2013, 02:07 PM
#1
5th Gear
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C3 upgrade: LS7 + 4L85E / 4L80E or 4L70E
I would like to upgrade my 1971 C3 (454/TH400) with a modern LS7 and transmission.
Turnkey Engine Supply offers a 540HP LS7 with an 4L70E kit for the Corvette.
But according to Jake's Performance the 4L70E isn't strong enough !!
If the 4L70E fits it might be the best solution even if it has to be rebuild sooner.
I have searched the internet and Forum, but not been able to find info that confirms what will fit in a C3 and what changes has to be done.
Thanks
Jens (Living in Denmark)
1971 454/TH400 with Steroids R&P
Turnkey Engine Supply offers a 540HP LS7 with an 4L70E kit for the Corvette.
But according to Jake's Performance the 4L70E isn't strong enough !!
If the 4L70E fits it might be the best solution even if it has to be rebuild sooner.
I have searched the internet and Forum, but not been able to find info that confirms what will fit in a C3 and what changes has to be done.
Thanks
Jens (Living in Denmark)
1971 454/TH400 with Steroids R&P
11-26-2013, 02:13 PM
#2
Le Mans Master
do you NEED an automatic?
11-26-2013, 03:10 PM
#4
get a 4L60-65 from RPM Transmissions who is a sponser on this forum and has a bullet proof reputation on their trans builds that will certainly more than hold the power. They put 4L60's trans behind LS7 and other highly modified LSx cars countless times.
I have one of their Level 5's 4L65's in my vette and beat the $hit out of it daily.
I have one of their Level 5's 4L65's in my vette and beat the $hit out of it daily.
11-29-2013, 07:38 AM
#6
5th Gear
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Thanks for the feedback.
I think I will take my chances with an 540HP LS7+4L65E next fall. (EDIT: I meant 4L70E)
If anyone has links/pictures of a similar setup please let me know.
Thanks
Jens
I think I will take my chances with an 540HP LS7+4L65E next fall. (EDIT: I meant 4L70E)
If anyone has links/pictures of a similar setup please let me know.
Thanks
Jens
Last edited by Pfingstl; 11-29-2013 at 10:12 AM.
11-29-2013, 10:08 AM
#7
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The 4L70e is just a newer version of the 4L60e/4L65e transmissions. It has an input shaft speed sensor. That sensor could help the transmission live if your PCM takes advantage of it. Basically, the PCM has code that measures the slippage during a shift and adjusts the line pressure to help it shift without excessive slippage. The input shaft speed sensor makes this more accurate compared to earlier code which did a similar thing.
The other thing that can help it survive would be to leave some torque limiting in place. Basically, the PCM has code that cuts engine torque during the shift. It makes for "soggy" shifts so many people tune it out. However, if you leave some of that in place it will help the transmission survive. This one relies on the tuning being accurate so the PCM can properly figure out how to cut a certain amount of torque.
The other thing that can help it survive would be to leave some torque limiting in place. Basically, the PCM has code that cuts engine torque during the shift. It makes for "soggy" shifts so many people tune it out. However, if you leave some of that in place it will help the transmission survive. This one relies on the tuning being accurate so the PCM can properly figure out how to cut a certain amount of torque.
12-31-2013, 12:32 PM
#9
Premium Supporting Vendor
www.RPMtransmissions.com Best in the biz along with a solid group of people to work with.
They built our trans that takes abuse in the Camaro5 shop car, 8.39's so far in the 1320, Louie and Farks is going to step it up a bit for '14
They built our trans that takes abuse in the Camaro5 shop car, 8.39's so far in the 1320, Louie and Farks is going to step it up a bit for '14