When does power break the drivetrain

[riboyster]

I'm on sprintex. Same same. Generally you are probably decently safe as long as you dont beat the shit out of the car.

[CSG Mike]

Originally Posted by riboyster

Very true. Most people pushing 300hp have enough tq for it to happen though.

Most Turbo cars at 300whp do. Most supercharged cars at 300whp do not.

[Tcoat]

Originally Posted by CSG Mike

Lets throw some monkey wrenches into all the misinformation and assumptions.

I've broken many transmissions at even 280whp. Why? Because transmission failures are not dictated by horsepower, but by torque and load.

I've broken axles both NA and FI. Axle failures are dictated by shock load, tire grip, and articulation of the CV joint. Big power can accelerate this in an unrelated manner, because guys with big power also tend to run stickier tires, which can exert a much higher shock load to the axles.

Clutches are also rated in torque. The stock clutch can hold 325-350whp, depending on the setup.

Another example of people wanting to apply hard numbers where there are so many variables that it simply becomes an exercise in futility.


YPYMYTYC

[bfrank1972]

As others have alluded to, whp can be loosely referenced, but really is not a relevant metric. Example is centrifugal supercharger vs a positive displacement supercharger or turbo. A centrifugal unit may produce a peak of 300whp, and a peak torque of 220 lb-ft. A turbo kit with a undersized unit may produce a peak of 300whp, and a peak torque of 260 lb-ft. Additionally a centrifugal unit will produce near peak torque maybe 5500-7000 where an optimized turbo kit may produce near peak torque from 3500-7000 rpm. What matters is torque, and how that torque is applied. I could have a "400 whp" turbocharged car that lasts forever because I drive like a granny and only let it loose when merging onto the highway. Or I could have "300 whp" and snap an axle because I spend my time slamming my car and hooning in parking lots

[86MLR]

I like hard numbers from manufacturers, they usually add in a safety factor, from their hard number I can set some goals and expectations.

Goal: max safe(ish) torque level so I'm not eating gearboxes.

Expectations: parts should last a reasonable time, I'm happy to replace parts, but the box must last

As for the clutch, I don't know what the OEM clutch is rated to torque wise, but, a clutch will be chosen by going a bit less in rating than what the box can take, I would rather my clutch be the fuse.

Yeap, any muppet can break parts from abuse.

This muppet just wants to get some info based on sound engineering principles to try and improve the performance whilst still retaining some form of reliability.

Yes, I will be going full throttle rowing through the gears and doing skids.

Maintenance is a given

I do believe I show my cars mechanical sympathy, even on track days I never do more than 3 hot laps.

Nothing lasts forever, especially when power ratings are matched or exceeded

This ain't my first rock show

Thanks for the data

[bfrank1972]

lol good to know

So this car is really not so overbuilt from the manufacturer compared to something like a Supra outfitted with a 2JZGTE. 165 whp/130ish wtq is about stock and what the car is engineered for with a fairly generous safety margin.

To simplify, you can expect:

Add 25% ( to those numbers everything else remaining the same with pretty low risk.

Add 50% - well tuned FI solutions on pump gas start around the 50% gains mark. Everything else buttoned up, well tuned, driven realistically, reports most cars work reliably, albeit you are well out of the design envelope for the car. Clutch life will be noticably shortened, and possibly malfunction depending on your torque curve.

Beyond that you have increasing risk - 100% increase you're at considerable risk of internals failure (again depending on torque curve, driving habits etc). Some motors hold. Some don't. IMHO it's a matter of time and you're no longer budging for motor longevity but rather budgeting considering a motor being a consumable item.

This is also assuming things are done right - supporting mods. Increased heat with power. Increased risk of catastrophic failure due to increased complexity (i.e. overboost, header/cat failure due to heat/pressure, etc.), lack of cooling, on and on. This probably is obvious to you but so many people neglect this part, and this makes a big difference in outcome when pushing a design 2x it's output.

Originally Posted by 86MLR

I like hard numbers from manufacturers, they usually add in a safety factor, from their hard number I can set some goals and expectations.

Goal: max safe(ish) torque level so I'm not eating gearboxes.

Expectations: parts should last a reasonable time, I'm happy to replace parts, but the box must last

As for the clutch, I don't know what the OEM clutch is rated to torque wise, but, a clutch will be chosen by going a bit less in rating than what the box can take, I would rather my clutch be the fuse.

Yeap, any muppet can break parts from abuse.

This muppet just wants to get some info based on sound engineering principles to try and improve the performance whilst still retaining some form of reliability.

Yes, I will be going full throttle rowing through the gears and doing skids.

Maintenance is a given

Nothing lasts forever, especially when power ratings are exceeded

This ain't my first rock show

Thanks for the data

[mrg666]

Originally Posted by Sleepless

3 years of JRSC with 265whp, 10+ track days a year in advanced group... no problems

2 years, 20k miles with JRSC (no track). No problems here either. I have only added oil cooler and Fluidampr for supporting the engine.

[Kris86]

Been doing spirited driving for about a year now at 400+hp on stock gearbox and stock axles with a exedy twin disc. Don’t expect it to last but, as stated previously, how you drive it, depends on how long it will last

My high boost map makes 461hp 369ft/lb

[Hags86]

The axle life seems to be largely dependent on how much the car is lowered. At 15mm lowered I've been OK but have some buddies at 25-30mm who break axles with less power/torque.

Has to do with the angle of the CV joint.