'85 5spd transmission hp/tq limit?
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From: Louisiana
'85 5spd transmission hp/tq limit?
Hi all, I just have what I consider a dumb question...
what is the hp/tq or should I say max boost on a healthy '85 5spd 13b transmission?
I'm running 10-11 psi on my blow-tru street ported 13b, the previous transmission (unknown state) gave up after doing a 15psi pass (going to 2nd gear). I got a good one in (took it apart, inspected, and installed) now I just keep questioning myself if I just pushed the limits of it running 15psi or it was just worn down. The, now broken, old transmission did NOT felt as smooth as the newly installed one does. I'm guessing it was really worn.
I'll post a picture of the damaged transmission in a few.
Thanks in advance, I searched but all it found was TII tranny swap
(yes... i know its better, but I cant afford the whole conversion right now.)
I DONT KNOW HOW MUCH HP ITS MAKING
what is the hp/tq or should I say max boost on a healthy '85 5spd 13b transmission?
I'm running 10-11 psi on my blow-tru street ported 13b, the previous transmission (unknown state) gave up after doing a 15psi pass (going to 2nd gear). I got a good one in (took it apart, inspected, and installed) now I just keep questioning myself if I just pushed the limits of it running 15psi or it was just worn down. The, now broken, old transmission did NOT felt as smooth as the newly installed one does. I'm guessing it was really worn.
I'll post a picture of the damaged transmission in a few.
Thanks in advance, I searched but all it found was TII tranny swap
(yes... i know its better, but I cant afford the whole conversion right now.)I DONT KNOW HOW MUCH HP ITS MAKING
Joined: Mar 2001
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From: https://www2.mazda.com/en/100th/
it isn't really a set number, as it depends on how you drive it, and what kind of condition it was in to start with.
if you're dropping the clutch, and doing hard launches and stuff, maybe 120hp/120lbs/ft, if you're nice to it, they ran these with a thicker case at 300hp...
if you're dropping the clutch, and doing hard launches and stuff, maybe 120hp/120lbs/ft, if you're nice to it, they ran these with a thicker case at 300hp...
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Joined: May 2001
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From: Cleveland, Ohio, USA
I trash them all the time with N/A torque. I am on transmission number four for this year and I've only been to three events and have done zero drag racing.
I try to change them out when the shifter starts racking back and forth with changing load (indicates the mainshaft is moving due to worn bearings) but the last one I wrecked lost 3rd gear the first time I shifted into it on my first run. Didn't even get to put any power down, just let out the clutch and bang. I have also destroyed 2nd gear and the transfer gear on other transmissions.
Get good at changing transmissions. The fix IS Turbo II transmission. Every time you have to swap in another N/A transmission is money that could have gone towards the Turbo II transmission that you should be getting. So, I'd turn the boost down for now.
I try to change them out when the shifter starts racking back and forth with changing load (indicates the mainshaft is moving due to worn bearings) but the last one I wrecked lost 3rd gear the first time I shifted into it on my first run. Didn't even get to put any power down, just let out the clutch and bang. I have also destroyed 2nd gear and the transfer gear on other transmissions.
Get good at changing transmissions. The fix IS Turbo II transmission. Every time you have to swap in another N/A transmission is money that could have gone towards the Turbo II transmission that you should be getting. So, I'd turn the boost down for now.
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Joined: Dec 2013
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From: Louisiana
it isn't really a set number, as it depends on how you drive it, and what kind of condition it was in to start with.
if you're dropping the clutch, and doing hard launches and stuff, maybe 120hp/120lbs/ft, if you're nice to it, they ran these with a thicker case at 300hp...
if you're dropping the clutch, and doing hard launches and stuff, maybe 120hp/120lbs/ft, if you're nice to it, they ran these with a thicker case at 300hp...
it has an ACT stage 2
Thread Starter
Junior Member
Joined: Dec 2013
Posts: 22
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From: Louisiana
I trash them all the time with N/A torque. I am on transmission number four for this year and I've only been to three events and have done zero drag racing.
I try to change them out when the shifter starts racking back and forth with changing load (indicates the mainshaft is moving due to worn bearings) but the last one I wrecked lost 3rd gear the first time I shifted into it on my first run. Didn't even get to put any power down, just let out the clutch and bang. I have also destroyed 2nd gear and the transfer gear on other transmissions.
Get good at changing transmissions. The fix IS Turbo II transmission. Every time you have to swap in another N/A transmission is money that could have gone towards the Turbo II transmission that you should be getting. So, I'd turn the boost down for now.
I try to change them out when the shifter starts racking back and forth with changing load (indicates the mainshaft is moving due to worn bearings) but the last one I wrecked lost 3rd gear the first time I shifted into it on my first run. Didn't even get to put any power down, just let out the clutch and bang. I have also destroyed 2nd gear and the transfer gear on other transmissions.
Get good at changing transmissions. The fix IS Turbo II transmission. Every time you have to swap in another N/A transmission is money that could have gone towards the Turbo II transmission that you should be getting. So, I'd turn the boost down for now.
hopefully it doesnt brake anytime soon
Ii'm running a turbo street ported 13B-RE. I stepped up to a TII trans a long time ago because I knew the OEM trans wouldn't handle the torque. When I went past 12 psi and the trans started making weird noises, I went the extra step of a performance rebuild that included cryo treatment (gear set and case), stress relief (gear set), and new bearings. After about a year of use at 18 psi with heavy water injection (i.e. power is more like 15 psi), I lost 3rd gear (pic).
I have the trans back now with the upgrade of a 2nd and 3rd gear cluster from a later year (2000?) JDM FD trans. The 2nd and 3rd gear sets in later years are substantially wider, and should be able to handle more torque.
At 15psi with a street port, I think you need a TII trans, minimum. If you plan to launch hard on a regular basis, you might want to consider a different trans altogether. If I had to do it all again, I think I might have opted for something designed to handle more torque. A modified Tremec TKO comes to mind.
You're probably pushing more than 4X the torque and HP the original 12A engine had -- or 3X what the original 13B engine had. It's unlikely the original trans (or anything else in the driveline) will survive for long.
I have the trans back now with the upgrade of a 2nd and 3rd gear cluster from a later year (2000?) JDM FD trans. The 2nd and 3rd gear sets in later years are substantially wider, and should be able to handle more torque.
At 15psi with a street port, I think you need a TII trans, minimum. If you plan to launch hard on a regular basis, you might want to consider a different trans altogether. If I had to do it all again, I think I might have opted for something designed to handle more torque. A modified Tremec TKO comes to mind.
You're probably pushing more than 4X the torque and HP the original 12A engine had -- or 3X what the original 13B engine had. It's unlikely the original trans (or anything else in the driveline) will survive for long.
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Thread Starter
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Joined: Dec 2013
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From: Louisiana
Ii'm running a turbo street ported 13B-RE. I stepped up to a TII trans a long time ago because I knew the OEM trans wouldn't handle the torque. When I went past 12 psi and the trans started making weird noises, I went the extra step of a performance rebuild that included cryo treatment (gear set and case), stress relief (gear set), and new bearings. After about a year of use at 18 psi with heavy water injection (i.e. power is more like 15 psi), I lost 3rd gear (pic).
I have the trans back now with the upgrade of a 2nd and 3rd gear cluster from a later year (2000?) JDM FD trans. The 2nd and 3rd gear sets in later years are substantially wider, and should be able to handle more torque.
At 15psi with a street port, I think you need a TII trans, minimum. If you plan to launch hard on a regular basis, you might want to consider a different trans altogether. If I had to do it all again, I think I might have opted for something designed to handle more torque. A modified Tremec TKO comes to mind.
You're probably pushing more than 4X the torque and HP the original 12A engine had -- or 3X what the original 13B engine had. It's unlikely the original trans (or anything else in the driveline) will survive for long.
I have the trans back now with the upgrade of a 2nd and 3rd gear cluster from a later year (2000?) JDM FD trans. The 2nd and 3rd gear sets in later years are substantially wider, and should be able to handle more torque.
At 15psi with a street port, I think you need a TII trans, minimum. If you plan to launch hard on a regular basis, you might want to consider a different trans altogether. If I had to do it all again, I think I might have opted for something designed to handle more torque. A modified Tremec TKO comes to mind.
You're probably pushing more than 4X the torque and HP the original 12A engine had -- or 3X what the original 13B engine had. It's unlikely the original trans (or anything else in the driveline) will survive for long.
The problem with the T2 tranny is the amount of power loss due to parasitic drag. Another problem is all the other stuff needed to get it in there. For these reasons I decided to go with NA trannies, for now.
Trans:
S5 NA with FB tailhousing and shifter
engine:
R5 13B ported to 74 spec
power adder:
S5 turbo at stock boost of around 7psi
One thing I do notice is it's hard to find 3rd but the shifter hasn't started to flop around yet. I think it's just slop in the housing so I'll go to a short throw but stock length shifter that's solid; no more rubber isolator in the lever. It should improve shifts a lot. Already have hockey puck motor mounts and a competition trans mount so the engine/trans stays put.
Trans:
S5 NA with FB tailhousing and shifter
engine:
R5 13B ported to 74 spec
power adder:
S5 turbo at stock boost of around 7psi
One thing I do notice is it's hard to find 3rd but the shifter hasn't started to flop around yet. I think it's just slop in the housing so I'll go to a short throw but stock length shifter that's solid; no more rubber isolator in the lever. It should improve shifts a lot. Already have hockey puck motor mounts and a competition trans mount so the engine/trans stays put.
Good thread to follow, as I'm building an 85 Base slick top with:
13B S4 T2, street port, stock everything else
12A trans
kia sportage 4:77 rear
no interior
I'm quite easy on cars, but I'll definitely roll into it a few times. Will be interesting to see what the trans does. I'm using it because I've got 4 or 5 of them, and I like the tight 12A gearing.
13B S4 T2, street port, stock everything else
12A trans
kia sportage 4:77 rear
no interior
I'm quite easy on cars, but I'll definitely roll into it a few times. Will be interesting to see what the trans does. I'm using it because I've got 4 or 5 of them, and I like the tight 12A gearing.
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