Correct Line pressure for high HP street driven 48re

What is everyone’s input on line pressure to run for a FMVB that is making around 900 hp now and will be turned up later on. Truck will have the new CRT Billet trans brake VB and the Thicker “billet” Belleville spring, Billet shafts, billet triple disc and so forth. I want it to shift firm and hold the power but also don’t want to have my back re adjusted every time I shift since it’s street driven.

I’ve heard 195-200 is good and pretty typical. I talked to Cope he said 220-225 psi line. That seems high to me. Any input?


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190-200 is a good spot. Easy shifts and a fmvb are two words that usually are not synonymous. Good luck

I daily mine. It’s not fmvb but I ran 200psi line pressure last year and plan on 220-225psi when the trans goes back in in a month or two. I’m upgrading to a quad disc(due to pushing through the dpc triple disc), all Billet shafts, extra large Billet direct drum with oversized piston, “Billet” Belleville spring, Billet foreword clutch retainer, Billet sunshell/reactionshell, and fully rollerizing my geartrain.

When you get much past 200 psi, torque converter ballooning becomes a big problem and you will quickly destroy your torque converter. Modified factory-style VB's have a built-in torque converter regulation circuit that usually keeps the converter safe when pressure is pushed up into the 250 to 350 psi range when using reverse. This same regulation circuit helps to regulate the converter pressure in forward gears when building boost against the converter at the starting line. Before you go cranking that new COPE VB up to 225+ psi, I'd be sure it has provisions to regulate torque converter charge/release pressure. From the few pictures I've seen, it does not have regulation built into the design so be careful with 200+ psi line pressure.

All that said, if you have success at elevated pressure with any brand of custom billet VB, be sure to share your results as we'd all love to see successful racing for all competitors where transmission issues become a thing of the past and it becomes a chassis/tuning race to see who can put the most power to the track, not who can band-aid their billet VB shifted tranny/converter setup to survive the whole event!

Big Blue24 said:

Before you go cranking that new COPE VB up to 225+ psi, I'd be sure it has provisions to regulate torque converter charge/release pressure. From the few pictures I've seen, it does not have regulation built into the design so be careful with 200+ psi line pressure.

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Thanks for the input! Would this be as big of an issue if the pressure is kept under 200 PSI?


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Cflanery88 said:

I daily mine. It’s not fmvb but I ran 200psi line pressure last year and plan on 220-225psi when the trans goes back in in a month or two. I’m upgrading to a quad disc(due to pushing through the dpc triple disc), all Billet shafts, extra large Billet direct drum with oversized piston, “Billet” Belleville spring, Billet foreword clutch retainer, Billet sunshell/reactionshell, and fully rollerizing my geartrain.

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Wish I had the money and time to do this!

ramthiscummins said:

Wish I had the money and time to do this!

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I bought the Torrington bearings and am hoping me and a couple buddies can tig weld them, and do the machining ourselves on a lathe. Figured we’d use some junk planetaries first to figure out what all we need to Machine and how much.

Let me know what you come up with for measurements to cut the groove in the planetary. I'm planning on doing this soon too. What are you going to shoot for as far as planetary clearance. I was thinking .003?

Cflanery88 said:

I bought the Torrington bearings and am hoping me and a couple buddies can tig weld them, and do the machining ourselves on a lathe. Figured we’d use some junk planetaries first to figure out what all we need to Machine and how much.

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I did this to a 47rh that we run in our drag truck. I used these torrington bearings, https://www.ebay.com/itm/Torque-Converter-Bearing-GM-LU-TH-700-R4-125C-180C-200C-440-R4-4T65E-4T60E-/272700572354

Finding what bearings were being used was the hardest part, so that should help some people out. Also the pins in the planets were pretty hard when cutting in the lathe so it'll take a good insert to get through them. I set the geartrain end play at .005" and so far so good.

Awesome, thank you for the info. I certainly appreciate it.

fosterriley said:

Thanks for the input! Would this be as big of an issue if the pressure is kept under 200 PSI?


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Under 200 psi is usually fine with all of the major well-built aftermarket torque converters.