Worth going forged internals for reliability ?
 

Good day,

After going over all the threads I found, I’d appreciate some feedback regarding my personal situation... I have a 2013 BRZ with 90k km on it, which I turbo’ed last year (340 crank hp on 94 octane, (270whp) and 260 tq). I’d like to be able to keep it another 6-8 years and thus looking for long term reliability. It’s my yearly daily driver including snowy winters, and I plan to do 1-3 days of HPDE per year, in a beginner group. I installed a dual oil cooler-radiator to keep oil temps at bay. I’m not an agressive driver, but will do like good accelarations from time to time. The clutch just got replaced, as the stock one was starting to slip.

I do not really have higher power goals, I would not mind having a bit more low end torque for passing on the highway when in 6th speed at 120km/hr, but otherwise, the tq I have I find is more than sufficient, and makes for a super predictable and balanced car during the HPDEs. Currently, max tq is achieved at 4k rpm and stays until redline. The professional tune done on dyno keeps tq lower up to that to protect the rods.

My goal is really to maintain long term reliability for many years to come, and protect the drivetrain and tranny to avoid such replacement costs. I have now invested a substancial amount in this car which I absolutely love, now I’m trying to see what is the logical and financially sound approach for the long term, as buying a new car this fun to drive would cost a lot more...

I have been recommended to invest in a built engine with forged internals to avoid bad surprises and long term reliability. Any recommendations for or againts such investment from your experience? Would this be a sound*»investment*» in attemping to keep the car for 6-8 more years ? Will it truly bring more reliability, or will the fact of having to take apart and rebuild the block actually cause other things to fail ? I understand forged internals would allow me to add substantial more power, but I would not want to put myself in a situation where I’d need to upgrade tires, tranny, axles, fuel pump, etc, etc to keep the car reliable.

Based on all I’ve read, my current setup is already just below the typically mentionned 300whp «safe*reliabilty point*» for stock internals. I am aware there is nothing garanteed and lots of factors involved, but The input from those with lots of experience would be much appreciated to help me enjoying my BRZ for years to come safely and reliably.

Thanks in advance,

I wanna say forged internals are for someone wanting more than the safe level of boost.

"Reliability" works but I've heard it'd be like 10k for a built engine and 10k doesn't sound like reliability.

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Save the money on the side and get a new OEM block when/if the current one grenades. Cheaper and less of a headache.

Not to hijack. How much better is the new block? Are there "safe" boost levels out there for it (higher than 7-9)?

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Theres plenty of second hand engines going around from people doing swap which are pretty cheap so it where me id by one of those and part out the bits I dont need on it

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2017+ blocks are supposed to be a bit stronger but not sure how much in practical terms. For road racing I would run a conservative tune anyway; for an occasional street pull can run a bit more hp/tq.

This is what I am thinking to get
Short block low compression
https://crawfordperformance.com/coll...12172301402185

and installation kit
https://crawfordperformance.com/coll...z-fr-s-gt86-86

plus high-boost pulley, injectors, fuel pump, cooling upgrades, tune, labor.

Looking like a little less than $10K over the JRSC I already have.

I wouldn't do any of this without the built short block.

Just do what I did and go balls to the wall

Built engines aren't inherently more reliable. I think reliability comes from responsible driving habits and preventative measures taken ( as you have with the oil cooler). I'd make sure you're doing anything you can to reduce knock correction ( better have catch cans!) and be extremely cognizant of your oil level. If it's survived this long, surely you're doing something right; I will agree with the sentiment that you should buy another block to be ready if something happens to this one, it's the cheapest path, it's a proven path, and it's a familiar path.

If you want more power, go with a built block, but understand that they have their own needs and aren't any safer from a reliability standpoint; building a brick wall that's thicker to withstand impact is great, but if the foundation is poor it'll come down regardless. Running a built engine low on oil, or thinking it'll withstand knock detonation much better would be silly ideals. Look at all the built WRXs and STIs that end up with multiple rebuilds. They aren't treating the principle cause of their failure and are just throwing big money at parts because nobody helps them understand the real reason for failure.

IMO, you are probably more likely to have an issue with spun bearings than anything else. I'd take steps to ensure that oiling is as little an issue as possible.

Edit: @DarkPira7e is right. A catch can would be a worthy investment.

Take the time to read through this thread if you haven't already.

so how much power are you getting with 10k of built and say an edelbrock?

Detune it a bit, or build in a lot of failsafes. Do every supporting mod as appropriate.

I have 38 track days on my turboed stock engine, with maps going up to 450 crank hp on Ethanol.

Generally speaking, which kind of failsafes are you using on your maps?

So far, in terms of failsafe, I’ve put a remote starter to warm the car up before I drive it, and stay in low boost map until the oil is at least 190F. I also have a 91octane map I could use, while fueling with 94. I’ll definitely look into a catch can or oil separator - it’s not something that was really on my radar to date. Besides that I run Gulf 5w40 and make oil changes every 5000km or sooner, and started getting my oil tested.

Is there anything else I missed I should be looking into ?

Cheers

Why are people quoting crank hp? Are they estimating crank horsepower because they believe they know what the drivetrain loss was on the day of their dyno test, and they know the accuracy of the dyno? Why quote peak horsepower too? Wouldn’t it be more important to know how the hp and torque look over all the rpms? What about supporting mods like e85, oil coolers, boost by gear, etc, or driving style like is the person doing smooth transitions on a track or are they doing hard transitions like static or rolling drags where the loads are significantly harder on the drivetrain?

Some conditions might be inherently harder on the drivetrain and require more focus on the internals. Some might strain the oil system and cause starvation issues, so they might strain the bearings or other components. Some might tax the fuel system. Some might tax the cooling systems based on climate conditions, FI setup and driving conditions, so the focus may need to be with e85 and cooling the motor with a larger radiator and/or oil cooler.

I think any suggestions should be taken with a grain of salt or be explicitly detailed.

I think, by looking at OP's location, that its because the dyno is a maha. Those dynos are able to get crank HP by calculating how much loss there is in the drivetrain. They are very precise if calibrated well.

Extensive amounts of datalogging and tuning.

What do you have for some common things say...

- heat soak (FMIC)
- run time (engine heat soak)
- fuel starvation (both DI and PI)
- overboost (failed bc or wg)
- bad fuel (low octane)

Things to think about.

Because that's what the OP started the conversation with, so that's how we keep the conversation consistent.

So it can estimate drivetrain losses for a car better? Why not just talk about whp/wtq, even if that is just an estimate too, subject to conditions and calculations. Dynos are for tuning.

I'd rather hear something like this, even though this setup (my setup) doesn’t really answer or inform the OP:

Been boosted for 5k miles (67k on car) exclusively on 91 with stock internals with a peak boost of 13 psi (85mm pulley) on a roots Harrop SC that was tuned by DT, that sees aggressive daily driving, while doing spirited canyon driving and occasional hard hoonigan pulls around town. Car has an OEM oil cooler and catch cans running full synthetic at 5w30. Garaged at home and work with Northern California weather (typically dry/warm).

Yes indeed, my dynos were done on a Maha dyno, and provided graphs for both Crank and wheel HPs. Basically, the torque curve climbs straight until peak torque of 260 pd-ft at 4000rpm, and then is flat until redline on high boost 94, on 91, it peaks just cuts at 213 pd-ft at 3500 rpm and then flat to redline (same curve but stops earlier) See charts attached- is it indeed more detailed than just a peak values. The car was tuned on that dyno. Besides that the kit was installed at about 65k km and now has 27k km on it, mostly city and highway, and 4hrs of on circuit HPDE. Oil cooler came 2 months ago as a result of temps seen during the hpde. 5w40 synth oil used and 94 octane gas used 98% of time. Car is maintained regularly by the same performance shop that manufactured, tuned and installed the turbo kit (intercooled). Weather is eastern Canada, so 15-30degC in summer and -10 to -30 degC in Winter...!

As mentionned earlier, I’m not an agressive driver, but will enjoy doing some strong acceleration from time to time, and plan to do 3-6 hrs (2-3 days) of HPDE per year. I now have an ODB2 reader with the ODB fusion app to monitor the car, but only have been monitoring oil temp so far.

@falcon_wizard if you dont mind me asking, is that a Lachute Performance kit?

Yes, it is their Stage 1 kit, similar to what is now offered as their LP Turbo OEM offering when buying a brand new BRZ.

From my research 300 is safe enough with a good safe tune and quality fuel, as long as your temps are kept in check.

Thats for the motor

Then it's the gearbox, 250nm rated, either have a few spare boxes or have yours built.

I was going to boost mine, I wanted a good lift in power, there's not alot of difference cost wise between 300-400hp, engine and bolt on wise anyway.

A built gear box and rear end brings substantial costs, upwards of 20k

So for the price of a new car you can make a boosted one "somewhat" reliable

Or, just grab a spare engine and box and replace when needed.

Me, I dropped my show bags, mine is staying NA

Are you saying the stock gearbox is rated for 250 Newton-Meters or 185 tq? The stock clutch could probably handle that for a long time. A Stage 1 Exedy will handle 185 wtq for a long time, guaranteed. The actual gearset in the manual should be able to take around 400 ft-lbs tq (540Nm) before there is real risk. That seems to be the consensus.

I have a rather large pile of quickly growing transmissions that would say otherwise. Any power level that requires a clutch upgrade to hold is putting the transmission at serious risk.

From manufacturer

I'm not surprised with 38 track days at 450hp. Let me guess, beginner group? Ya, probably not.

I misspoke. I was thinking 400hp, not torque, was the common consensus, but that would mean like 300ish tq. I'm sure someone can break the stock transmission just like they break the stock engine when NA.

Saying any power level that requires a clutch upgrade... What do you consider requires? The stock clutch might handle who knows how much torque for a few dyno pulls. Can you clarify? Do you mean for the life of the car or for at least a few years? The stock clutch is not rated very high. I have the Exedy Stage 1 which is essentially just a pressure plate upgrade and is rated to hold like 205 tq, but the consensus is it holds much higher. I'm at 13 psi, and the clutch is holding fine, and so it the gearbox. You are saying I didn't need to upgrade the clutch, or are you saying that since I did, I am putting the transmission at serious risk?

Does it matter that I likely don't see the low end torque that your turbo'ed 86 does, let alone the same absolute level of torque?

So 35+ tq is all the transmission will be able to handle? :laughabove:

That's why mine is staying NA.

My old RB 25/30 Skyline went thru gearboxes like oil changes, it was always easier to buy a used box for a couple of hundred than outlay 25-20k for a built box

The 750nm of torque would eat the case hardening right of the gears, sticky tyres and big torque = broken stuff

For me, to have a reliable (ish) car, it cannot go too far past the OEM limit, this is why I'm staying NA

If I was to boost it, I would need to upgrade the driveline to give me some more confidence

I'm not saying you cannot give it some boost, some superchargers won't push the limits, and a well chosen turbo may not as well, but, why spend that much money for 30nm and ??hp, not good bang for buck IMO

If I had more disposal income I would build a sweet 350-400hp car, with a gearbox and rear end built to take the additional power, mad skids would be had...

But, the kids have got to eat and stuff, and the girl does like to shop

Building cars was so much simpler when I was single and didn't have kids

Speakin of trannys has anyone done an up rated box yet? (From what I understand its essentially the same 6speed that was in S15 silvias, not known for their strength)

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The stock clutch will easily hold basic FI, as well as basic FI and a mild Ethanol tune. While each clutch is different with the individual user and condition, OEM will generally hold 250wtq (300 crank) comfortably. Some will hold as high as 280wtq. Clutches are either going to hold or not hold; there is no in between.

Telling me you're at 13 psi tells me nothing; I need output figures, not a measurement of pressure. My 360whp/450 crank hp, is at only 10.5 psi.

I've broken transmissions at as low as 230whp/200wtq (Superlap battle 2017 estimated hp), but this was at the end of a track session in pretty extreme weather. That one literally gave out on my cooldown lap, when I wasn't even really putting any stress on it.

So going back to the topic of the cost/benefits of having an engine rebuilt with forged pistons, rods, etc, for reliability purposes rather than pursuing increased power output; based on the posts above, based on actual experience, have the motor been a weaker link than the transmission, or vice versa in that power range ? (Say 260/270 wtq/whp range on 94 oct) my understanding was that the rods were the weakest link, but maybe the tranny is not far behind ? For reference, when I replaced my stock clutch, it was almost 6 yrs old with 90k km on it (25k with the turbo on), and still had about 33% left on it. So arguably I could have kept it for a while still, but started to feel a bit of loss of torque transfer to the wheels during acceleration and so went ahead with an upgraded one.

Going through the logic a bit, if forged blocks allow for increasing the power and torque, it would seem to indicate that such block would be able hold better still than a stock block at lower power levels - assuming quality parts & worksmanship on the build, are there reasons why this would not be the case ? Or is it simply that people would rather edge their bets and change the block when and if it failed, rather than proactively have it reinforced before it goes ? My understanding is that the cost of profesionally building/installing my block would be about the same, propably a bit less than the total cost& labor of replacing mine after it failed with a used stock block. In this equation, I include labor by a qualifie shop, as I do not DIY. So I am trying to assess the cost/benefit of doing this proactively - cash flow aside, if there is a high degree of certainty that I would have to have the block replaced or rebuilt sooner or later (based on me wanting to keep the car 6-8 more years), then I would also weigh in the benefit of choosing a convenient time to build the block, vice having my year round Daily Driver stranded anywhere/anytime and being forced to do something then, require towing, etc.

Thoughts ?

The math to me looks like ~$5500 for a built engine (after good engine core is returned) plus install labor. I'm not sure what the labor is for swapping an engine but it doesn't look hard on this car so maybe $8000 all in for a built motor installed and tuned. If you roll the dice and lose, your core is no good, so it would be ~$10k plus rental car because it would take some time before your new engine is ready. So, if you lose the gamble, it would essentially cost an extra ~$2500 plus rental car. If you win the gamble, you save ~$8000.

I would just lower the boost a touch and forget about the risk that is introduced by trying to run it near the stock limit for 6-8 years.

No in between? Then how to stock clutches go bad? Because they start getting worn down or the surfaces get glazed. A clutch will start slipping at high loads then slip everywhere. I’m sure your experiences are more immediate and extreme because of your use, but to say it will hold or not is not accurate. Some people burn through a clutch in a few pulls. Some burn through them in a few thousand miles. Some in 20k. Some in 200k. That is why I asked for clarification because saying once someone REQUIRES a new clutch then the tranny is at high risk is not really very specific at all.

I did a remote tune with DT. I didn’t dyno tune, and I don’t need to waste money on seeing a dyno number. I said above I’m on 91 with a Harrop kit with an 85mm pulley. You should know the approximate numbers. You have more hp with less boost because you have better AITs and I’m sure less resistance: my roots is hotter than your turbo; my 91 is hotter than your E85; my cats give more resistance so higher boost pressures than your catless setup (I’m assuming you’re catless here).

Im sure running super sticky tires and tracking the shit out of a car can do that to the transmission. Which part of the transmission broke?

Perhaps you misunderstand. Let me further clarify.

As you said, a clutch is either holding the power, or not holding the power. It either is, or it isn't. The state can be stated as 1 for holding, and 0 for not holding. There is no "sort of holding", or 0.5 state; it is binary. If at any point the clutch is slipping when unintended, it is not holding the power.

If a good condition clutch that can hold power as intended from the factory, cannot hold your FI power, you are putting your transmission at risk. Subaru is very good about engineering cascaded failure points into their cars. The clutch is intentionally designed to fail before something else does.

An air-water heat exchanger has lower IATs than an air-air intercooler for burst output. My output figures are on a stock front pipe and stock exhaust.
The main cat is deleted by the turbo kit. I have enough exhaust restriction that my car's net exhaust volume is quieter than stock.

Likewise, I run tires all across the spectrum, but I cannot load the transmission more than what the engine's output is. The example of my low output transmission failure was on Michelin Pilot Super Sport, which is not a sticky tire at all.

Forged doesn't make it wear out slower. Forged stops things from cracking/breaking/stretching/snapping/etc. It can also give you some knock resistance. If you want reliability, get a good conservative tune.

Clutches fail from brute force and from excessive heat. They don’t see the heat brakes do because clutches work statically as you know, but there is heat and slip that occurs. The weaker the pressure plate and/or the softer the material, the more slip can occur. A person can go through a clutch that can hold the power much the same way as weak-material brake pads may only survive a few track days. I’ve read many threads with comments that the OEM clutch failed quickly after FI, but I haven’t seen many threads on broken transmissions, except from people tracking their heavily modified and high powered cars. I’ve seen far more engine failures discussed over transmission failures. While you are knowledgeable, I feel your experiences don’t mirror what the average person will do with their car on the track and/or with FI in general.

It is disengenuous to say the transmission broke during a low output situation. Unless you had torn it apart to see, it is just as likely the damage/fracture/stress/deformation occurred beforehand, but finally failed later. That would be like throwing a straw on a camels back and declaring that straw broke the camels back, but not the other weight that was already there.

While torque will stay the same, stickier tires and lower gears will cause more resistance. Consistently dropping gears while flooring it or doing launches from a dig will put considerably more stress on the transmission too. If every transmission was rated for the worst case scenarios while expecting OEM longevity then everyone here should be considering a built engine, clutch and transmission upgrades, even if they are stock.

The reality seems to be that the engine will fail before the transmission. Considering the transmission was rated at 185 tq, and the OP has 260 tq, it seems to be holding. If it blows then a used transmission is cheaper than a new clutch, but the same can’t be said about the engine. If the OP wants to add reliability, a built engine isn’t a bad idea and cheaper done before the engine blows.

Let me clarify more since you use the word static.

Friction is either static (clutch held) or kinetic (clutch did not hold). There is no in-between state between static and kinetic.

The transmission failed on the first outing with the turbocharger at the low output level. It was never ran with FI prior to that, and was never ran with stickier tires than a 200TW, non-71R/Rival-S/A052/Sur4G.

Right. The clutch sees both types of friction. The coefficient of static or kinetic friction will change with heat, as the material properties change. Heat can shorten the clutches life dramatically besides torque. I’m still of the mind that a clutch upgrade could be needed, yet doesn’t mean the transmission is now a ticking time bomb. It could be there to manage heat or to minimize heat by getting a better bite so there isn’t as much slip or kinetic friction. The OEM clutch could hold the peak torque, but not be able to manage the heat enough to manage that torque for very long before it is eventually not holding the peak torque at all. Clutch destruction can be immediate or gradual.

Regardless of all that, you’re basically saying the OP is already surpassing the trannies abilities, so any goals for extra power will inherently be even less reliable. You’re also saying 450hp with the right supporting mods is reliable because your engine didn’t break with that power after intense track days (and he is a beginner), so he doesn’t need to do a built engine.

That quote is what I meant when I said the transmission probably didn’t break then, even if it finally gave out on the cool down lap. Maybe you didn’t mean it to sound like the transmission is such glass that it will break in such a scenario, but that is how it sounded.

If a driver is putting a significant amount of heat into the clutch, they need to revisit their technique; clutches are not designed for that. The clutch should have minimal amounts of kinetic friction time; static friction will not introduce heat to the system.

Yes, I maintain that anyone who upgrades past what the stock clutch can handle is now putting their transmission at significant risk. Subaru engineers stepped failure points into their vehicles.