larry Posted May 8, 2020 Share Posted May 8, 2020 Hi Guys Been off here for a while but missed the best place for advice. I want to swap my stock 5spd gearbox on my 1999 turbo for a 5spd that can handle around 460BHP max as the turbo im looking to put on will be pushing 450BHP max. Any gearboxes off the newer scoobys that would fit? Cheers Larry Quote Link to comment Share on other sites More sharing options...
ROSSCOSM Posted May 8, 2020 Share Posted May 8, 2020 Im not sure any of the 5spds can handle that kinda power mate unfortunately. 350 tends to be the opinion of the 5spds power limit 1 Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 8, 2020 Share Posted May 8, 2020 I assume you've had a sti ej207 or forged engine fitted? As any standard classic engine would be on its limits at 350hp along with any classic gearbox (even sti ones) . A later hawk wrx 5 box usually handle a bit more power but only up to high 300's . 6 speed is the usual upgrade path as they can handle 700hp + (£1.5 k for the box) otherwise if you want to keep the 5 speed gearing, it's fitting a straight cut gearset and converting it to handle the power .(£2.5k+ fitting) 1 Quote Link to comment Share on other sites More sharing options...
larry Posted May 9, 2020 Author Share Posted May 9, 2020 I understand and agree with you guys. I have had an engine rebuild a few years ago non-forged. I have seen people with non-forged subaru's running 400 BHP on a stock engines perhaps they do not abuse it everyday.. who knows. It would appear I would need a six speed although I was really hoping not to change the 5 speed as I think the gear ratios are shorter on the 6 spd box. Quote Link to comment Share on other sites More sharing options...
ROSSCOSM Posted May 9, 2020 Share Posted May 9, 2020 You can buy stronger gears for a 5 spd and have it rebuilt if you want to keep the ratio but its not cheap thats why most people just put a 6spd in like all car mods really its how deep your pockets are Quote Link to comment Share on other sites More sharing options...
larry Posted May 10, 2020 Author Share Posted May 10, 2020 I don't have any pockets at the moment 😢 lol Does that mean you would have to change the rear diff and prop shaft? Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 10, 2020 Share Posted May 10, 2020 Think the only stock Subaru engine that would safely run over 400hp is probably the ej207 ,as its a semi closed deck and forged from the factory . Yours will probably be open deck and classic rods and pistons are on their limits at 360 to 38hp ish . A later hawk 5 speed will bolt straight into your set up with just box ,cradle and gear stick linkage . As long as it's the same ratio as your existing box , you find this out by googling both gearboxes ty54 numbers and find one with the same final drive ratio as your existing box n diff . After turning 2 x5 speeds into 4 speeds ,I went for a uk ratio 6 speed which seems to have the best of both worlds. Shorter 1 to 5 than a 5 uk 5 speed but longer 6th for carriageway economy 😉 Quote Link to comment Share on other sites More sharing options...
larry Posted May 10, 2020 Author Share Posted May 10, 2020 So Hawk eye 5 speeds have the same ratios and should be a straight swap to my classic? Do you know how much Bhp this one can handle? 6 Speeds are defo the best option but also pricey. As you have had 5 spd and now 6 aside from the economy what difference is there in drive-ability and when you put your foot down? Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 10, 2020 Share Posted May 10, 2020 You need to google your existing gearbox ty number and buy another box with the same final drive ratio , so it matches your existing rear diff . Think I've read that they handle 380hp due to bigger casings and slightly stronger gearsets to cope with the extra torque fron the 2.5 ltr . But I've never personally owned one ,so I'm can't guarantee that's gospel plus any second hand 5 speed box can be a gamble at higher hp . I got 310 miles from my v1sti running 359 hp on a family trip to cornwall , with 4 up and a bootfull of cases. Always seem close to boost with the shorter 1st to 5th ,so I prefer the drivabilty too . Quote Link to comment Share on other sites More sharing options...
larry Posted May 10, 2020 Author Share Posted May 10, 2020 Which number on the Chasis TY is for the final drive ratio if you know at the top of your head for the gearbox as it consists of a lot of numbers. So you were running 359hp on a stock 5 speed box? if so its pretty good. If I purchase a 6 speed box what else would i need to complete the system? Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 11, 2020 Share Posted May 11, 2020 Gearbox ty number is on a white sticker ,on the bellhousing near the starter motor . You need to google that number to find your existing ratio and buy a box with the same ratio . Nope I've busted a good sh ty52 uk turbo box @330hp and then 2x jdm ty52's at 347hp within a fortnight 🙄 So I've been running the uk 6 speed for about 7 yrs at mid 300's . Youd need the same as the hawk plus a 6 speed prop , existing 5 clutch assembly and front shafts work with a 6 speed box fine Quote Link to comment Share on other sites More sharing options...
Tidgy Posted May 11, 2020 Share Posted May 11, 2020 hawk wrx box is designed for 2.5 so longer ratios. i ran one at 390bhp 420 ftlb for about 14k miles no issue on a forged 2.5 hawk. options are, A - hawk 5 speed, at that power at the top of its limit (assuming 450) and no telling how long it will last B - Have your box rebuilt with a gear kit, but need to be carefull what gear kit you use as they have different ratings, also allows ratio changes and can be custom set for what youw ant (short ratio 1-4, lonnger motorway gear 5th), wont get much if any change from £2.5-3k. I have straight cut ppg gearkit in my old car and sounded epic haha C - 6 speed from an sti, which is by far best option simialr price to rebuild with gear kit, downside is its 90kg heavier setup had to decided on this option several times and tried em all haha, One thing i did note was you say your engine isnt forged, if not forget anythign about 350 unless your planning on rebuilding again. Quote Link to comment Share on other sites More sharing options...
larry Posted May 11, 2020 Author Share Posted May 11, 2020 Thanks Savage so the 6 speed from a hawk should be able to handle the power of 460bhp?. Tidgy Thanks for the options. I don't know how much a 5 spd can handle as they arnt the same in strength as a 6. Bit of a gamble lol Rebuilding it with a gear kit to costly and lengthy.. 6 speed from an sti im assuming its the hawk eye? seems the best option for power and reliability. Seen some on eBay for around £1500 No engine isnt forged I did rebuild it two years ago. I have seen people run 400BHP on stock engines so im looking to test the water here. I dont abuse my car but give it the occasional sprint here and there whilst ensuring coolant, oil etc is checked. Quote Link to comment Share on other sites More sharing options...
Tidgy Posted May 11, 2020 Share Posted May 11, 2020 it wont last at 400 i can tell you now, may people try to get away with it and it always ends with rods and pistons the wrong shape. Dont forget these car are now 20 years old so not alot new is doen that hasnt been done or tried before. 6 speed form any year will be fine at that power level, its gonna be more about getting it to fit, widetrack will mean hubs etc all bneed to be done as well and iirc the driveshaft is the wrong length for a classic. Quote Link to comment Share on other sites More sharing options...
larry Posted May 12, 2020 Author Share Posted May 12, 2020 I have seen some 6 spds on eBay TY856WN4CA here is the link is this all what is needed? https://www.ebay.co.uk/itm/Subaru-Impreza-STi-6-Speed-Gearbox-Conversion-TY856WN4CA-Genuine-77k-miles-WRX/303556325881?hash=item46ad5df1f9:g:Ky0AAOSw0LteXVVK Quote Link to comment Share on other sites More sharing options...
Tidgy Posted May 12, 2020 Share Posted May 12, 2020 someone else will have to answer that as im not fully up on the codes Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 13, 2020 Share Posted May 13, 2020 Youd need to google both the code on your gearbox ty5### number off the white sticker near the starter motor and the one off the 6 speed to see if the ratios match . Tbh with standard uk pistons and rods youd be lucky to get 350hp before something broke or the heads lifted. You say other people run 400's on a standard engine , maybe a ej207 but I've never seen it on a standard ej20 g ,ej20 k or ej205 . Tbh 330hp in a 1300 kg car is no slouch and a much cheaper and safer target hp . Quote Link to comment Share on other sites More sharing options...
larry Posted May 22, 2020 Author Share Posted May 22, 2020 They ran them on classic tubro 2000's id imagine they had the 2.0 not the ej207. Agreed it would be more safer but having it rebuilt and maintained I want to ideally see what my standard engine is capable of as people say different things along with their own experiences. Just sourcing a turbo is a bit of a nightmare. Quote Link to comment Share on other sites More sharing options...
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