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The mkiv Supra Owners Club

auto box upgrade


Andyhannah

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seriously, you say you want an uprated box "cheap" but are wanting 700bhp (?) which is big money, i run 500rwhp and the box is in the twilight of its life, i have a boostlogic built box on the way, if you are willing to put the mullah into the engine surely you must consider the whole car as well, if you want cheap i would just have a second hand spare stock box ready to go when the one in the car goes and just keep swapping them, just upping the line pressure really isnt going to solve anything when your clutch packs are shot, what is the 700bhp for are you going drag racing if yes you could do with a better box than stock

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The stock box will never take 700, well it will but if it lasts 10 minutes your doing well. :)

 

There is no avoiding it mate if you are looking at that sorta power you need to get a built box/Hi-stall or go manual.

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I disagree, the stock box will run plenty of BHP. 700 may be on the high side but why not suck it & see? What's your current auto box worth? Yeah, not very much, so why spend good money replacing it when you don't need to. If you've got the money left after you have 700hp then upgrade the box.

 

On the other hand, as soon as you start upping the power you MUST get a hi-stall torque converter to make the most of the new power levels.

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IMO, upgrading your cars power to 700 bhp and then not doing anything about the gearbox is silly. Why cut corners, especially with something as important as the gearbox. The stock box will break at those power levels, no question about it....

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I disagree, the stock box will run plenty of BHP. 700 may be on the high side but why not suck it & see? What's your current auto box worth? Yeah, not very much, so why spend good money replacing it when you don't need to. If you've got the money left after you have 700hp then upgrade the box.

 

On the other hand, as soon as you start upping the power you MUST get a hi-stall torque converter to make the most of the new power levels.

 

I Disagree with you.

 

Having experience in the whole autobox issue it WILL fail at a lot less that 700bhp.

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ok. yes your stock box will break with that power... but why not like me test the box to see how far you can take it... if you are gonna have 700hp then you will need to get a bl box, but before you change them over.... wind the boost up and run the stock box just to see how much it will take. as there are so many pepole on here who are so happy to state that the stock auto box cant handle anymore than 500 bhp.... this we have already proven not to be the case as i myself have been running 550 for six months now, and yes it gets a hammering.. and i have had no issues yet... soon i will be winding up the boost all the wy on race fuel using the stock box to see how much it will take.., ye i know it will break eventually but i'm gonna do it all the same;)

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;) yes John we have, some can and some can't thats all fella.... but i will still be testing the box all the same... not on a public road of course, using race fuel etc.. i guess i'm just one of those curious types eh.

like i said, the stock box will break at 700 but i'm willing to try and get 600+ out of one:eyebrows:

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;) yes John we have, some can and some can't thats all fella.... but i will still be testing the box all the same... not on a public road of course, using race fuel etc.. i guess i'm just one of those curious types eh.

like i said, the stock box will break at 700 but i'm willing to try and get 600+ out of one:eyebrows:

Burt i can understand your logic to a degree but failure of the stock box at high power figures is 100% inevitable, mine is running 500 rwhp and the full boost change ups are now becoming slower and slower i have given in and splashed the cash and gone for the BL, how far will you take pushing the standard box - until it fails catastrophicly and wipes out the engine with it, as gamer says i cannot understand modding the engine but leaving the tranny if you have a 700 bhp engine budget and a zero £ tranny budget i think a re-assesment of prioritys is called for, BTW could andyhannah explain the reasoning behind his "700bhp" figure when he obviously hasn't got the money for the tranny to hold this power - crazy - next he'll be posting asking for advice on cheap j-spec brakes to stop it lol

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Burt i can understand your logic to a degree but failure of the stock box at high power figures is 100% inevitable, mine is running 500 rwhp and the full boost change ups are now becoming slower and slower i have given in and splashed the cash and gone for the BL, how far will you take pushing the standard box - until it fails catastrophicly and wipes out the engine with it, as gamer says i cannot understand modding the engine but leaving the tranny if you have a 700 bhp engine budget and a zero £ tranny budget i think a re-assesment of prioritys is called for, BTW could andyhannah explain the reasoning behind his "700bhp" figure when he obviously hasn't got the money for the tranny to hold this power - crazy - next he'll be posting asking for advice on cheap j-spec brakes to stop it lol

oh no i wont push the box to that point of total breakdown and the Bl tranny will be on the workshop floor. ready to go in.. i would never risk my engine to prove a point;)

i totally agree with you Paul.. building a 700 hp car without doing anything to the box is plane stupid, as i have said in both previous posts that it will break.. he will defo need to budget for a built box, not sure why he is building a car of this spec though for the road:think: surley if its for the strip a th400 box is defo the way to go... i would love to see the spec on this car as both you and i are aware that anymore than 500-600 is pointless on the road as it becomes unusable.

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I Disagree with you.

 

Having experience in the whole autobox issue it WILL fail at a lot less that 700bhp.

We'll have to agree to disagree then.

 

My experience is 550+hp for 20k miles & still had smooth quick gearchanges. It's sitting in my back garden now in case the upgraded one goes.

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We'll have to agree to disagree then.

 

My experience is 550+hp for 20k miles & still had smooth quick gearchanges. It's sitting in my back garden now in case the upgraded one goes.

 

 

550+ is manageable to some extent with the use of a hi-stall, aftermarket cooler (preferably with a fan), frequent fluid changes and taking it easy between the 1-2 shift.

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