Power handling of gearbox

[Guest]

I have a TY752VBBAA 5MT, in a bog standard weighted BG5 s/w (god knows what that is 1400Kg?). My KW goals for the time being are maximum 260KW. Will this box cope with a bit of head room? Would a drag launch be likely seeing the end of it do you think?

[Guest]

Simple answer: It's gonna a'splode.

Long answer: It would handle as a daily driver, about 200 - 210kW every day, and if you treat it like crap, it would die after about a year... if you go by a rule of thumb, if you treat your box like shit, for every 10kW of power you add, take off 2 weeks of expected life from the box.

This is from personal experience and opinion, feel free to add your input other people, THERE ARE NO WRONG ANSWERS.

[Guest]

even a RA strengthened box wouldnt like 260kws atw for very long would it?? ??? especially if your doing the odd drag!

[nt_a_foz]

I doubt the 5 speed would handle a big launch at that power...at least not very many if it did handle one or two....

Get a 6 speed

[dubbedup]

Big launches= gearbox lunched

[Jammasta]

 nt_a_foz']

I doubt the 5 speed would handle a big launch at that power...at least not very many if it did handle one or two....

Get a 6 speed

After having the syncros replaced and the gears inspected, My 5 speed handle well over a dozen HARD 5500rpm launches with antilag cracking 1.2bar of boost. About 6-8 of those at meremere on a sticky (stickier than the road) track.

It was fine.

[quote name='Hopai said:

for every 10kW of power you add, take off 2 weeks of expected life from the box.

THERE ARE NO WRONG ANSWERS.

That is a complete and utter BS statement.

Taking off 2 weeks of life for something that could have an infinite life is akin to asking how long a piece of string is.

[dubbedup]

how much power were you running turtle?

[Jammasta]

200KW atw.

Reason i mentioned it, i would imagine that a car running 200kw atw with Antilag, would be (IMHO) harder launching than a 250kw with no boost assist. (i know the 60ft times were def quicker).

It is likely to blow at 250, but some people get lucky and get freak cars which seem impossible to blow up.

[funkytown]

I will tell you real soon what one handles, just got new power and my 5mt put back together.. (pushing 233kw atw daily)

I do hope it lasts : :

Im not stupid on mine though - never gets launched (serial), but does get some track beatings and it gets the foot up it once rolling in any gears..

You need to factor in the clutch here as well, as any quickish get away i try just spins my clutch (factory STI jobbie) ((this was with about 200kw atw)). A harsh clutch will shock your drive train sooo much more.

 nt_a_foz said:

Get a 6 speed

Truth

[Wiretap]

170wKw with track suspension (softer suspension absorbs some of the initial torque load, making life easier for the gearbox) is enough to nuke a WRX/RS box, I can tell you that much, my never-launched, otherwise-fine 5MT just dropped a tooth off first gear after a couple of firm pulls through first.

There are more factors than power that go into the destruction of a gearbox, torque, the clutch springs, your suspension, condition of your engine mounts, etc, all count.

[Guest]

In general its torque that kills gearboxs not power - in some ways smaller turbos tuned with lots boost early on are harder than big turbo's running the same power.

Short ratio gearboxs - Type R / RA have an advantage that they are lower geared so less stress on the box

6 speeds are stronger plus similar low gearing.

[Guest]

 nt_a_foz said:

I doubt the 5 speed would handle a big launch at that power...at least not very many if it did handle one or two....

Get a 6 speed

^ True... another option.. But pricey.. DOG BOX

[Guest]

 

True... another option.. But pricey.. DOG BOX

Stop... I'm dribbling!

Just to entertain the thought for 3 seconds...

How much would a 6 speed set ya back roughly.

Would it be a hard match up to the BG?

[BC5RA]

 Wiretap said:

170wKw with track suspension (softer suspension absorbs some of the initial torque load, making life easier for the gearbox) is enough to nuke a WRX/RS box, I can tell you that much, my never-launched, otherwise-fine 5MT just dropped a tooth off first gear after a couple of firm pulls through first.

There are more factors than power that go into the destruction of a gearbox, torque, the clutch springs, your suspension, condition of your engine mounts, etc, all count.

I've never done a 1st gear on any of my RS gearboxes including my RA and they all have seen hard use with extensive stiffening of the suspension.

But then I have seen many with blown 1st and 2nd gear clusters as well as 5th.

It's mainly shock loading, poor clutch choice and no mechanical thoughtfulness that blows them.

[Old Skool Subbie]

 gadget said:

 

True... another option.. But pricey.. DOG BOX

Stop... I'm dribbling!

Just to entertain the thought for 3 seconds...

How much would a 6 speed set ya back roughly.

Would it be a hard match up to the BG?

The cheapest ive ever seen one was $2000. seen prices include 2500, 3000 3500, 4000, 5000 and even up to 7k

[Guest]

 

The cheapest ive ever seen one was $2000. seen prices include 2500, 3000 3500, 4000, 5000 and even up to 7k

Holy crap... 2K I would almost consider, but... Holy crap!

[ODB]

any mechanical equipment will treat you aswell as you treat it.

be harsh on them and dont put good fluid in etc and they can go with a half harsh launch.

be nice to them and they can last a long time.

If you are running around 200kw atw with a grippy clutch and giving it death all the time you will break the 5mt in a wrx or gt legacy.

strengthening or 6mt would be best.

[BC5RA]

 Solja said:

So what are the relatively safe power levels for the stock drivetrain components?

the list below is a general guideline and represents the relatively safe power levels for WRX and STI stock drivetrain components, assuming a safe tune. Keep in mind that modifying your car to these power levels greatly increases the risk of component failure due to increased stress. It doesn’t mean that the components will fail, just that there is an increased risk

WRX Engine: ~400 whp

STI Engine: ~450 whp

WRX transmission: ~350 whp / 350 ft.lb torque

STI transmission: ~600 whp / 600 ft.lb torque

WRX/STI clutch: ~400 whp / 400 ft.lb torque - clutch will last, but not long at these power levels

WRX/STI axles, differentials: ~600 whp / 600 ft.lb torque

Intercoolers

Intercoolers can be - air-to-air, where the air passes through an intercooler core that has fins in it / air-to-liquid, also called air-to-water, where the air exchanged heat with some sort of liquid coolant / Hybrid

Intercooler locations are usually - in the front bumper (frontmount) / on top of the engine (topmnt) / front fenders (sidemount)

Intercoolers introduce/enhance turbo lag. With any intercooler setup the air does not move directly from the compressor into the intake manifold, but rather has to go through the intercooler piping and the intercooler core and compress there. So the longer the intercooler plumbing, the more turbo lag is present

Lag

Turbo lag can be defined as the time it takes to bring the turbo up to speed for it to build boost and operate efficiently. You can also think of turbo lag as the time it takes for your turbo to start compressing air and the engine to begin producing significant power. .

so small turbos have less turbo lag since they need less exhaust gases to spool up. Big turbos need more exhaust gas to spool up, so they inherently have more turbo lag

What other things can you do to minimize the turbo lag on your car, independently of which turbo you have? There are several things you can do

heat-wrap your exhaust manifold - this will keep the exhaust gases hot inside the exhaust manifold / run leaner, but still safe Air fuel ratios running leaner produces higher exhaust gas temperatures, contributing to faster turbo spool / get a programmable electronic boost controller that will try to spool your turbo faster by keeping the wastegate completely shut until a certain level of boost is achieved / dont get a frontmount they increase your turbo lag due to the length of piping

Remember, the bigger the turbo, the more turbo lag it introduces. You need more RPM to spool up the bigger turbo

In extreme cases, when a huge turbo is installed, 2.0/2.5L engine will not have enough gas flow even at 7000/8000 rpm and the turbo will not operate efficiently

With huge turbos, modifications to heads, valvetrain and engine block are necessary to rev the engine up to 8,000 rpm and higher to produce enough exhaust gas flow for the huge turbo to be efficient and build boost. Huge turbo wont even spool at lower rpms, and you will have a huge amount of turbo lag - or wait time before the turbo spools up

Safe tune

A safe tune is a state of tune when your car does not experience any negative issues, such as: (detonation);

knock / detonation / high exhaust gas temperature - EGT / too rich or too lean of a mixture / and other issues that inevitably lead to the above three

A tune does not have to be unsafe to be conservative or aggressive. You can make lots of power with a safe and aggressive tune without sacrificing driveability, reliability or longevity

What is a conservative tune, Conservatively tuned maps are generally, - on a richer side - have conservative timing - have fairly low boost - knock free

An aggressive tune, is generally - on the leaner side - allows you to run higher exhaust gas temps and spooling turbo faster - more aggressive timing - more boost

AFRs require special attention, as they will be different from car to car

Retune

As a outline, you should always re-tune your car when the following characteristics are altered by modifications

air flow - higher flowing intake, more boost, bigger turbo / fuel delivery - bigger injectors, fuel rails, fuel pump,water injection

When you increase the airflow, you will need to re-tune your subaru to adjust the fueling accordingly. without proper tuning more air will make your car run dangerously lean, which will result in detonation which could damage the engine

Tuning must be done to accomodate larger injectors, since they will supply a lot more fuel than the stock injectors. Higher flowing parallel fuel rails will also flow more fuel and require tuning. An aftermarket fuel pump will generally increase the fuel pressure in the fuel lines, thus either a re-tune or an adjustable fuel pressure regulator are required

What cloud are you from? This particular part is pure BS.

The best part is the STI transmission handling 600lb/ft of torque, absolute crap.

All of those numbers are rubbish; did you make them up or pull them down from some other site?

[Guest]

Haha you talking about Subaru here?............those figures a damn generous

[BC5RA]

 Solja said:

ok bc5ra it was removed and if you wanna remove yours i aint on any cloud anoth said

Why did you remove it?

It was open for discussion.

[Guest]

OK, so I have my answer anyway. The idea was to get a gauge on how much power my 5MT would take all day every day. What I have pulled from this is that my power goal of 220KW - 260KW is something I cant bolt out of the gate with at every chance I get. .. With this gearbox.

Putting the power down with the rolling weight would be fine, but get my box built or a 6MT if I have any idea of taking her down a 1/4 mile regularly... Unless, I like spending money and countless hours swearing lots and fixing things. I like swearing lots, but that's about as far as it goes. ;D

Thanks for all your input. Anyone have a 6MT for sale

[funkytown]

 gadget said:

OK, so I have my answer anyway. The idea was to get a gauge on how much power my 5MT would take all day every day. What I have pulled from this is that my power goal of 220KW - 260KW is something I cant bolt out of the gate with at every chance I get. .. With this gearbox.

Putting the power down with the rolling weight would be fine, but get my box built or a 6MT if I have any idea of taking her down a 1/4 mile regularly... Unless, I like spending money and countless hours swearing lots and fixing things. I like swearing lots, but that's about as far as it goes. ;D

Thanks for all your input. Anyone have a 6MT for sale

interesting.. been running for a (very) short time now on 235atw and my 5MT actually feels quite good.. Its my stock (almost new) clutch that feels like its the weakest link and wants to spin trying to get it all away to fast...

[Guest]

Wicked! Keep us updated with that one... God luck for now.

[BC5RA]

 funkytown said:

interesting.. been running for a (very) short time now on 235atw and my 5MT actually feels quite good.. Its my stock (almost new) clutch that feels like its the weakest link and wants to spin trying to get it all away to fast...

And you will want to keep that the weakest link, cause as soon as you step up the compound/clamping pressure etc your gearbox will become the next load bearer.

Although having a slipping near new clutch is no fun, I would take a small step up if needed, perhaps talk to a clutch builder for a custom rebuild of your clutch.

[funkytown]

 BC5RA']

[quote name='funkytown said:

interesting.. been running for a (very) short time now on 235atw and my 5MT actually feels quite good.. Its my stock (almost new) clutch that feels like its the weakest link and wants to spin trying to get it all away to fast...

/quote]

And you will want to keep that the weakest link, cause as soon as you step up the compound/clamping pressure etc your gearbox will become the next load bearer.

Although having a slipping near new clutch is no fun, I would take a small step up if needed, perhaps talk to a clutch builder for a custom rebuild of your clutch.

yup +1.. what i had already summized.. It only does it if i try to get away "real" quick.. its about right for now. Still manages to get a wheel or two spinning no probs in the dry or wet..