How much hp/torque a v2 STi gearbox hold?
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How much hp/torque a v2 STi gearbox hold?
Hi all,
I'm considering of changing my 97 impreza turbo box for a v2 STi one. Roughly, what sort of power can they handle, and can some later spec imprezas (classic shape) hold more?
Regards,
Subaru Collector 555.
I'm considering of changing my 97 impreza turbo box for a v2 STi one. Roughly, what sort of power can they handle, and can some later spec imprezas (classic shape) hold more?
Regards,
Subaru Collector 555.
Don't expect to get much life out of it over 300bhp 
If you're running 1.4 bar at about 300 ftlbs with a good clutch you will be stripping gears without even realising.
Later 754 boxes are stronger allegedly but it's a lottery. The only sure fire way of ensuring reliability is a six speed. I have a six speed in my classic and it's awesome. You enjoy the power and never flinch at banging in 2/3rd for hairpins and redlining the boost through each gear You simply can't do that with an OEM 5 speed box, so what's the point in having a forged engine to exploit
If you're running 1.4 bar at about 300 ftlbs with a good clutch you will be stripping gears without even realising. Later 754 boxes are stronger allegedly but it's a lottery. The only sure fire way of ensuring reliability is a six speed. I have a six speed in my classic and it's awesome. You enjoy the power and never flinch at banging in 2/3rd for hairpins and redlining the boost through each gear
You simply can't do that with an OEM 5 speed box, so what's the point in having a forged engine to exploit
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Thanks for the reply,
I knew that the 5 speeds wouldn't hold much hp but I thought it might not have applied to the STi's. Looks like a 6 speed is on the shopping list what else would I need as well to do the conversion?
The owner said that it has been rebuilt by APi impreza with something called a hybrid box? Does anyone know what that means, also will it not handle anywhere near 400hp?
Regards,
Subaru Collector 555.
I knew that the 5 speeds wouldn't hold much hp but I thought it might not have applied to the STi's. Looks like a 6 speed is on the shopping list what else would I need as well to do the conversion?
The owner said that it has been rebuilt by APi impreza with something called a hybrid box? Does anyone know what that means, also will it not handle anywhere near 400hp?
Regards,
Subaru Collector 555.
Last edited by User 21721; Dec 5, 2013 at 10:51 AM.
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From: @Junc 12, M40 Warwicksh; 01926 614522 CV33 9PL -Use 9GX for Satnav. South Mids Alcatek ECu dealer
Thanks for the reply,
I knew that the 5 speeds wouldn't hold much hp but I thought it might not have applied to the STi's. Looks like a 6 speed is on the shopping list what else would I need as well to do the conversion?
The owner said that it has been rebuilt by APi impreza with something called a hybrid box? Does anyone know what that means, also will it not handle anywhere near 400hp?
Regards, Subaru Collector 555.
I knew that the 5 speeds wouldn't hold much hp but I thought it might not have applied to the STi's. Looks like a 6 speed is on the shopping list what else would I need as well to do the conversion?
The owner said that it has been rebuilt by APi impreza with something called a hybrid box? Does anyone know what that means, also will it not handle anywhere near 400hp?
Regards, Subaru Collector 555.
A "hybrid box" is one built here using non standard ratios. So it might be STi gear ratios, but with a different final drive ratio than usual.
TY754 late type from 2003 to 2005 seem to be able to withstand up to 380 hp in our experience, but will probably fail sooner than later. Cryogenic treating NEW gears does give stronger results, but cryo treating used gears is possibly a waste of money.
6 speed or forged type 5 speed gears are the solution.
Good Luck, David API
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No STi Vers 2 TY-752 type box will take anything anywhere near 400 hp They were probably OK at up to 350 hp when NEW, but after 17 or 18 years of use cannot even be expected to take that level of power.
A "hybrid box" is one built here using non standard ratios. So it might be STi gear ratios, but with a different final drive ratio than usual.
TY754 late type from 2003 to 2005 seem to be able to withstand up to 380 hp in our experience, but will probably fail sooner than later. Cryogenic treating NEW gears does give stronger results, but cryo treating used gears is possibly a waste of money.
6 speed or forged type 5 speed gears are the solution.
Good Luck, David API
A "hybrid box" is one built here using non standard ratios. So it might be STi gear ratios, but with a different final drive ratio than usual.
TY754 late type from 2003 to 2005 seem to be able to withstand up to 380 hp in our experience, but will probably fail sooner than later. Cryogenic treating NEW gears does give stronger results, but cryo treating used gears is possibly a waste of money.
6 speed or forged type 5 speed gears are the solution.
Good Luck, David API
Thanks for the useful advice
Subaru Collector 555.
My v2 RA box didn't like the recently fitted 320bhp motor, 5th gear went awol 2k miles later. Mind you I did give it some welly.
I was hoping to squeeze out another 30 brake but a gearbox upgrade has got to come first.
I'm looking at replacement options atm £500 for a used standard box that will probably last just as long, used dog/straight cut box (don't know if could stand the noise) 6 speed conversion or maybe a PPG helical box.
I don't really want the extra weight of a six speed or the hassle of changing shafts and hubs.
API David: Are there any rebuild options for a blown standard RA box?
I was hoping to squeeze out another 30 brake but a gearbox upgrade has got to come first.
I'm looking at replacement options atm £500 for a used standard box that will probably last just as long, used dog/straight cut box (don't know if could stand the noise) 6 speed conversion or maybe a PPG helical box.
I don't really want the extra weight of a six speed or the hassle of changing shafts and hubs.
API David: Are there any rebuild options for a blown standard RA box?
Last edited by edsel; Dec 5, 2013 at 06:32 PM.
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From: @Junc 12, M40 Warwicksh; 01926 614522 CV33 9PL -Use 9GX for Satnav. South Mids Alcatek ECu dealer
Options
We have many options Steve, Thanks for your call.
Our transmission department creates all sorts of wonderful things to suit a customers needs and due to my experience with World Rally Championship transmissions, l can usually translate what a customer wants into a gearbox that fits the job properly.
The problem with the early RA box are well documented and we have vast experience in keeping them going. [ providing they are running on realistic - for the application - horsepower ] .
The main problem is case flex and we have a case strengthening trick that we learnt from the early rally boxes from Prodrive.
The second is that the key locating 5th gear is only barely locating the gear by about 1 mm, way too shallow. Over the years natural strain momentum of the gear against the key makes the edges rounded off and eventually the gear rides over the key jamming it in 5th or even shattering the gear.
We spark erode a .97:1 RA gear if it can be saved and fit the 754 type Key. that way it is on the same spec as the 754 and 754 5th gears can be used to get better cruising revs and fuel consumption.
It is fair to say that most of our 'hybrid' boxes are one offs to suit what the customer wants. But if that is what the job dictates, then we are here to help you.
Great advert eh ??
David APi 01926 614522
Our transmission department creates all sorts of wonderful things to suit a customers needs and due to my experience with World Rally Championship transmissions, l can usually translate what a customer wants into a gearbox that fits the job properly.
The problem with the early RA box are well documented and we have vast experience in keeping them going. [ providing they are running on realistic - for the application - horsepower ] .
The main problem is case flex and we have a case strengthening trick that we learnt from the early rally boxes from Prodrive.
The second is that the key locating 5th gear is only barely locating the gear by about 1 mm, way too shallow. Over the years natural strain momentum of the gear against the key makes the edges rounded off and eventually the gear rides over the key jamming it in 5th or even shattering the gear.
We spark erode a .97:1 RA gear if it can be saved and fit the 754 type Key. that way it is on the same spec as the 754 and 754 5th gears can be used to get better cruising revs and fuel consumption.
It is fair to say that most of our 'hybrid' boxes are one offs to suit what the customer wants. But if that is what the job dictates, then we are here to help you.
Great advert eh ??
David APi 01926 614522
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