Anyone blow a stock engine running 8 psi(<300HP)

[bfrank1972]

Holy zombie thread

Sent from my SM-G965U using Tapatalk

[DarkPira7e]

Originally Posted by bfrank1972

Holy zombie thread

Sent from my SM-G965U using Tapatalk

At least the reply was from someone who had been asked a question, and not someone asking an additional stupid question of someone who hadn't been on since 2014

[Irace86.2.0]

Originally Posted by Goingnowherefast

People should comment whether they track the car or not. I have no doubts in my mind that you can keep a low power FI setup (sub 300 whp) alive for maybe the life of the car *if* the car is only a street car. That same setup might only last a few track days with a fast driver.

Assuming oil or fuel starvation has been addressed and that cooling has been addressed, are you suggesting track conditions will cause someone to fatigue out the rods or that someone will downshift aggressively enough to increase forces or that stickier tires on a track will increase the load too much to snap rods?

I haven’t tracked my car, but I routinely take the car to redline. I’m on E85 at a bar of boost on a Harrop SC, Ace150 and Michelin Pilot Sport 4Ss. No issues so far.

I always wonder if the issues that lead to motor failures are more about other issues than power in those track situations like not using E85, not properly lubricating or cooling the car or some type of starvation issue. It would be nice to know for sure when a failure happens.

[x808drifter]

Originally Posted by Irace86.2.0

Assuming oil or fuel starvation has been addressed and that cooling has been addressed, are you suggesting track conditions will cause someone to fatigue out the rods or that someone will downshift aggressively enough to increase forces or that stickier tires on a track will increase the load too much to snap rods?

I haven’t tracked my car, but I routinely take the car to redline. I’m on E85 at a bar of boost on a Harrop SC, Ace150 and Michelin Pilot Sport 4Ss. No issues so far.

I always wonder if the issues that lead to motor failures are more about other issues than power in those track situations like not using E85, not properly lubricating or cooling the car or some type of starvation issue. It would be nice to know for sure when a failure happens.

I your car is tuned properly fuel does not play a role. Unless you get bad gas.

[Irace86.2.0]

Originally Posted by x808drifter

I your car is tuned properly fuel does not play a role. Unless you get bad gas.

Knock resistance, keeping the combustion chamber/oil/engine cooler, less boost needed for the same power output, less variability in power depending on the ambient air temps means more consistency.

Were you making a point that I missed?

[bfrank1972]

It's too complex IMHO. We humans like to simplify things but in this case don't think it's simple, too many variables and combination of those variables can lead to a failure.



Forget all these commonly addressed factors like heat management, knock resistance, driving habits, etc. Consider basic variance in motor construction - high volume 'cheap' motors typically have a fair amount of variance that is acceptable within the intended design envelope. You can get away with it if your motor has to manage a peak of 160 whp and 130 wtq - "get away with it" meaning they can produce a motor at specific planned cost without having a ton of stock failures/warranty claims.



Now, double the torque and hp output - you're way outside that design envelope. Any weaknesses/flaws in your particular motor will quickly be made apparent - given most manufacturing is relatively consistent and most motors will manage fine, but any variance/weakness will very quickly become apparent.


Once that happens we all try to point fingers at the obvious things, but we all have to keep in mind that pushing a motor way past its original parameters is a game of russian roulette to some extent.

[Goingnowherefast]

Originally Posted by Irace86.2.0

Assuming oil or fuel starvation has been addressed and that cooling has been addressed, are you suggesting track conditions will cause someone to fatigue out the rods or that someone will downshift aggressively enough to increase forces or that stickier tires on a track will increase the load too much to snap rods?

In my eyes, here are a few reasons that track work is so mechanically stressing on vehicles compared to street use:

1. Higher oil temperatures from sustained high rpm's could lead to early bearing failures and pre-mature component wear as the oil becomes less viscous with temperature increase.

2. Heat soak from high load, high rpm use increases the IAT's. More so, when you are in traffic on track you are not able to get clean air. Higher IAT's/charge temperatures mean increased chances of knock, detonation or LSPI.

3. Depending on track layout, you may be forced to run the car in conditions that you wouldn't normally find on the street. Example: There's sections of tracks that are up steep hills (Laguna Seca for example), which see's long WOT's up hill. This is a scenario where you will be loading the engine (almost lugging) far greater than on the street. Another example is there's a local track that has you between 6800-7400 rpm on and off WOT for like 15 seconds. On the street, it would be very odd to hold 6,800+ rpm for that long.

Originally Posted by Irace86.2.0

I haven’t tracked my car, but I routinely take the car to redline.

Have you been on track before? It's hard to fathom how hard track work is on a vehicle if you haven't experienced it. Doing a 10 second pull on the street is one thing, but a car can see 15-20 minutes+ of sustained WOT at high engine speeds during a single session. There's a reason why some motorsport dampers can go 100K street miles without a rebuild, yet recommend a rebuild after 20-30 track hours. It's just simply magnitudes harder on components.

[x808drifter]

Originally Posted by Irace86.2.0

Knock resistance, keeping the combustion chamber/oil/engine cooler, less boost needed for the same power output, less variability in power depending on the ambient air temps means more consistency.

Were you making a point that I missed?

You specifically mention not using E85 as a reason that may cause a blown engine.

What I am getting at is that what fuel you run should be what fuel you are tuned for and has absolutely no bearing on blowing an engine.
Having E85 is nice but not always available.

Knock resistance - Tune for less timing based on what fuel you run.

Less boost needed for the same power output - Shouldn't be tuned for more boost/power than you can safely get with your fuel anyway.

The way your argument is worded comes to the logical conclusion that everyone should run full on race gas.

[Irace86.2.0]

Haven’t. Just the canyons n street. Never made time for the track.

[NIKOLA]

Yeah, I blew a rod bearing with my Spintex SC pushing 8-10 psi (75mm pulley) and e85 was used exclusively. It took 3-1/2 years to reach failure. So I don't think the tune was at fault at all. Car has been sitting in the garage since September. I will be getting it in the shop in January though. New Manley forged rods going in with new King XPG main and rod bearings and a new stock crank shaft. I don't intend to generate more than 300 -320 hp at the wheels. However, I will ask since I can't find the information online. How much HP can the stock pistons handle before they disintegrate??? 120 hp per piston, 150 hp per piston ?? More?? Less?? If anyone knows please post the information for me. I'd like to get a set of forged JE Pistons at 12.5:1 stock compression, but not if the stock pistons can actually handle at least 400 BHP or more. I'm not looking to make crazy power for my daily driver.

[jflogerzi]

As other have said don't boost unless your prepared to drop another or built engine in. Hell people have spun a rod/bearing in NA cars on the track.

[botbs]

Originally Posted by Matt@Cosworth

one thing to mention that hasn't been so far is exhaust back pressure

the stock system is quite restrictive and going up to a minimum of 2.5" if not 2.75 to 3" really pays dividends and will help with the motor life as less back pressure means its more resistant to knock and less knock events = a happier motor

If only 2 choices, which one would have less knock events?
1) Catless header + OP + high flow cat front pipe but with stock exhaust?
2) 2.5" Cat-back only

Trying to minimize the noise but want to have less back pressure to have less knock events.

Thanks!

[tomm.brz]

of course the catless is going to be better for knocks and power
the bigger catback will help by a very small %, and will be more noticeable with forced induction

[DarkPira7e]

Originally Posted by botbs

If only 2 choices, which one would have less knock events?
1) Catless header + OP + high flow cat front pipe but with stock exhaust?
2) 2.5" Cat-back only

Trying to minimize the noise but want to have less back pressure to have less knock events.

Thanks!

Catless header would remove a large restriction. I had my car catless but using stock catback. Ran 330whp with a turbo for a while but my j02 recall ghosts kept from from going more than a few months- timing chain guide let go.
I certainly had no more or less knock events due to stock exhaust on the turbo. If you use an external wastegate and dump to atmosphere, you have a lot less backpressure but also when you're in boost past wastegate spring pressure, it's quite loud.