AHHHHHHHHHH!!!!!

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[HATEnFATE]

ahhhhhhhh!!!!!!!

Look what i came accross today......it's heartbreaking.
luckily it's not mine but it does belong to a friend of mine. This is what what happens if you don't watch your boost levels though.

I'd like to point out however that this isn't how a Toyota piston rod would look. This is an SR20 rod and you can see that by the insignia on the center of the piece. A Toyota rod would fail in the middle. This rod is heavy and built to take boost. a spike, however, will kill anything. This one had a cap bolt break.

When your boosting your cars remember that it's not hard to get this to happen. If you buy a kit, make sure your boost creep and boost spike protection are the best they can be.

[THansenite]

Whew!  When I first saw the pic, I was scared that came out of the newly boosted tC you were building.  Glad to hear that car is still alive.

[nebster]

pretty

[need4speed]

i thought the same thing as tony...phew!  figured jason wanted to see how high he could get the boost levels..haha  well im relieved

[AcidBurn]

So for those of us who are car idiots. This is a piston rod I assume, and the bottom part has been shattered? How did that happen(I realize you said boost spike, but I dont know what that means).

[HATEnFATE]

I was thinking of just typin in the phrase "AHHHHHHHHHHHHHHHHHHHHHHHHH" and then posting later about what it really was.

[nebster]

edit (roy):

We'll have none of that here.....

edit (ben)

aww why not its all in fun

[HATEnFATE]

So for those of us who are car idiots. This is a piston rod I assume, and the bottom part has been shattered? How did that happen(I realize you said boost spike, but I dont know what that means).

Boost spike or boost creep is exactly what they sounds like. boost spike is a unwanted spike in the boost level that exceeds what your boost is set at. In cars where the engine isn't built to be boosted this can mean disaster. tC's are great examples(honda's are built the same way). These engines were built to be efficiant. Light parts and higher compression make them efficiant but not as strong. the Rods are thin and can only support a max of about 10 psi, even that is pushing it a little for reliablility. If your running a turbo setup at 8 psi and for some reason you get a boost spike and get around 13 psi, you've likely done damage to the rod by bending it or possibly damaged a bearing by adding too much stress.

In a car thats turbocharged from the factory, extra strength is built into the rods to be able to reliably handle the stresses of boost over a long period of time. These cars are more able to handle boost spikes because of the stout nature of the internal parts.

tC's are able to handle 10, MAYBE 11psi before you start cause irreversable damage. My sentra's SR20 on the other hand was designed as a turbo engine and was turned NA in the states. The rods are built to accept the added stress. My engine can support up to 25 psi before damage start to occur. Eclipses and Supra's are the same way. They are designed to take the stress of boost and can handle larger amounts of it before damage occurs.



What happened in this case was not a boost problem but a weak metals(metal fatigue) problem. The rod cap bolt was over-stressed(possibly over-tightened or under-tightened or a manufacturing flaw) and it snapped. What is appears is that the bolt snapped off, the rod cap bent allowing the piece to separate from the crank. When the crank came back around, it hit the rod and snapped the end off the one side. The portion of the rod lowest in the picture is actually separated from the rod itself, they're just lined up so you can see the bends.

What boost would do is this.



or this

[Doanrs]

I can't belive that a forged rod would bend that much. That's wild. How bad is the crank and block?

[grizzly_choppers]

Nice walkthrough Jason.

For Steve (but not Steve) the only thing he didn't describe is "boost".  That is simply a term used to describe air and fuel being forcably introduced to the engine's cylinders.  That is generally done with either a turbocharger or supercharger but can also be done at extremely low levels (technically) with any kind of electric fan or pump.  That is how they can claim on ebay to be selling superchargers for $50 or whatever, they're just fans.

Just thought I'd add that to be complete.

-Lando

[HATEnFATE]

Thanks Alex, you are right, I didn't descrive what boost was.

Turbochargers are a type of forced induction system. They compress the air flowing into the engine. The advantage of compressing the air is that it lets the engine squeeze more air into a cylinder, and more air means that more fuel can be added. Therefore, you get more power from each explosion in each cylinder. A turbocharged engine produces more power overall than the same engine without the charging. This can significantly improve the power-to-weight ratio for the engine.

In order to achieve this boost, the turbocharger uses the exhaust flow from the engine to spin a turbine, which in turn spins an air pump. The turbine in the turbocharger spins at speeds of up to 150,000 rotations per minute (rpm) -- that's about 30 times faster than most car engines can go. And since it is hooked up to the exhaust, the temperatures in the turbine are also very high.

Turbochargers allow an engine to burn more fuel and air by packing more into the existing cylinders. The typical boost provided by a turbocharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50 percent more air into the engine. Therefore, you would expect to get 50 percent more power. It's not perfectly efficient, so you might get a 30- to 40-percent improvement instead.

One cause of the inefficiency comes from the fact that the power to spin the turbine is not free. Having a turbine in the exhaust flow increases the restriction in the exhaust. This means that on the exhaust stroke, the engine has to push against a higher back-pressure. This subtracts a little bit of power from the cylinders that are firing at the same time.

[bottlefedturbo]

mmmmm.... those pistons look delicious.... just dip em in chocolate and serve..... yumm low compression!

[THansenite]

Nice walkthrough Jason.

For Steve (but not Steve) the only thing he didn't describe is "boost".  That is simply a term used to describe air and fuel being forcably introduced to the engine's cylinders.  That is generally done with either a turbocharger or supercharger but can also be done at extremely low levels (technically) with any kind of electric fan or pump.  That is how they can claim on ebay to be selling superchargers for $50 or whatever, they're just fans.

Just thought I'd add that to be complete.

-Lando

Actually, those blowers on eBay have been shown to actually reduce airflow.  Air is already sucked into the engine at a pretty high rate (around 250 cubic feet per minute if I remember correctly).  If you have a fan that only moves 100cf/m, you are actually restricting the airflow because air is entering the intake faster than the fan is forcing air.  

It is important to note that you would not get 350 cf/m in that case, you would still only be able to get 250 cf/m.  However, the fan actually creates turbulance and reduces the amount of pipe air can flow through.  That is the reason that it actually lowers performance.  

You have to remember that turbos are spinning at several TENS of THOUSANDS of revolutions per minute forcing more air than any electric fan could (at least on a car's electrical system).

[HATEnFATE]

The average spool of a turbo is between 100,000 and 150,000 rpm, usually on the higher side.

[THansenite]

That is true, they can spool up to 150,000 rpms, but that is usually at full throttle with high-end ball bearing turbos and extremely free-flowing exhaust.