5250 High Performance Blog

Subaru Engine Failures | a 'built' motor makes more power, but why?

[fa icon="calendar'] Jun 22, 2017 10:00:00 AM / by Mike Wiener posted in Subaru Engine Failures

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Subaru Engine Failures | choose performance upgrades wisely

Having a "built" motor means you have replaced some or all of the factory components with upgraded aftermarket ones.

The term "built" is very loose term and varies from only a few improved components to a well built one with major upgrades, choose wisely.

A common thing to do is what is called a piston slap. A new or used stock shortblock has it's pistons removed and replaced with upgraded ones. This is a very economical way to upgrade a motor, but it doesn't always yield the best results.

In the case of a used shortblock, installing new pistons without properly preparing / honing the cylinder walls will cause ring seating problems and engine failure. This is probably the cheapest way to get a "built" motor and you will get what you pay for.

This is where taking shortcuts will lead you to failure | A proper built motor will have the entire rotating assembly upgraded. This includes crankshaft, rods, and bearings in addition to the pistons. There are hundreds of ways to piece these parts together, but all of them should start with a new or newly machined engine block. The cylinder walls must be perfectly round and have the proper cross-hatching for the rings to seat properly.

If the rings don't wear in properly, there will be excessive blow-by and a loss in compression. Improperly seated rings will lead to low power, oil consumption, and failure of the motor.

When building your shortblock, the pistons are the single most critical decision. There are many to choose from and some may not be correct for your application.

Factory pistons are hyperutectic. This means they are very strong, but very brittle. Similar to a pane of high quality glass, they can take enormous stress loads, but a sudden shock load can cause them to shatter. Detonation, or knock, is the primary killer of pistons. It only takes one fairly mild detonation event to shatter a stock piston.

Aftermarket pistons are of the forged design and are made of a softer material than hyperutectic ones and can handle a sudden knock event without breaking. These are not bullet proof though... a very strong detonation or a series of them can still destroy forged pistons.

When pushing an engine towards higher power, knock will happen. Forged pistons are what allows a tuner to push to the limit, then back off a little bit when that limit is found. Without the ability to take these light knock events, max power cannot be found.

Even on a perfect tune, knock happens. Bad gas or very high operating temperatures can casue a detonation. It's extremely difficult to prevent all knock, so make sure your pistons are up to the challenge, choose your build wisely.

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E85 | more Turbo Power after you bolted on all those mods

[fa icon="calendar'] Jun 13, 2017 9:30:00 AM / by Mike Wiener posted in Building Horsepower, Turbo Upgrades, E85

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Building Turbo Power in Colorado | Now that you have bolted on as many go-fast parts as you can find online, what’s next?

You read many forums, and the real issue is that you are still cautious because this is your daily driver.

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Dyno Shop | Ready for the Track | not so fast speedracer

[fa icon="calendar'] Jun 8, 2017 9:15:00 AM / by Mike Wiener posted in Building Horsepower

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So you think after spending big chunks of money on power / suspension upgrades, you now have a race car.

You've modded the engine and now it's putting out 150hp more than stock. You've upgraded the suspension with coilovers and chassis stiffening braces and sway bars. You've fit the widest wheels and tires for the most grip. Your new brakes are HUGE!

  • The race track is a great place to push limits, feel G forces, and have enormous fun that isn’t realistic on the street. There is no comparison.
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Rotary Engines | Cooling Systems oil and water

[fa icon="calendar'] May 22, 2017 8:00:00 AM / by Doug Sherwood posted in Mazda Rotary Rebuilds

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REbuilding rotary engines that have been damaged due to neglect in cooling seems to be a pattern for high horsepower turbocharged builds. This is caused by builds that use parts that should be put on piston engined cars, not rotaries.

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We are hiring in Colorado | We Need Technicians & Tuners

[fa icon="calendar'] May 14, 2017 11:10:28 AM / by Doug Sherwood posted in hiring

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Colorado Performance Shop | We are hiring Technicians and Tuners, NO Saturdays !!


We are looking for a technician that wants to learn and grow in the high performance automotive field to become part of our team.

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High Performance Maintenance | Understanding Spark Plugs

[fa icon="calendar'] May 5, 2017 7:00:00 AM / by Mike Wiener posted in spark plugs

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Spark Plugs | Why they need attention with your high performance car

Every car on the road that runs on gasoline has spark plugs. Some cars even have 2 plugs per cylinder. Bust just like different cars have different motors, different motors have different spark plugs. On most cars, checking or changing your plugs is a simply DIY task. On a few cars, getting to the spark plugs requires a bit a disassembly or difficult access.

Most inline and V type engines have the plugs right on the top of the motor making access a snap.

H type and transversely mounted motors may have plugs mounted low and on the side of the motor or on the backside tight against the firewall. These plugs may be difficult to access or require the removal of the intake manifold. These types of motors are better left to the professional.

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High Performance cars will Pass Emissions ...

[fa icon="calendar'] Apr 26, 2017 7:00:00 AM / by Mike Wiener posted in Fabrication Services, Emissions

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Emissions continues to be a problem for modified cars.

Most newer cars only need a scan of the cars computer system to pass emissions. But that's not always as easy as it sounds.

We recently had a customer that had bought a Hennessey Challenger SRT600 from out of state and was really surprised to find out it would not pass emissions here in Colorado. Here is what happened:

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Signs your Rotary Engine is Junk | Rotary Engine Rebuilds

[fa icon="calendar'] Apr 13, 2017 6:30:00 AM / by Doug Sherwood posted in Mazda Rotary Rebuilds

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The Mazda rotary engine is one that is loved by a few and dissed by many. Why is that?

With a power to weight ratio that of many supercar engines, the rotary makes great power for the size that it is. With that comes responsibility.

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Rebuilding the Rotary Engine | the rotating combustion chamber

[fa icon="calendar'] Apr 10, 2017 7:55:40 AM / by Doug Sherwood posted in Mazda Rotary Rebuilds

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The Rotary engine is the only high performance engine that has one, the rotating combustion chamber.

This means that rebuilding them is much more than using conventional thinking.

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Firewall Welds | Subaru firewall repairs vs the dealership repairs

[fa icon="calendar'] Apr 8, 2017 11:30:00 AM / by Mike Wiener posted in Subaru Firewall Clutch Pedal Repair

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Failing clutch pedals on 2008 and newer Subarus seems to be a continuing issue. We are getting at least one a week to repair at the moment.

As these cars age, I am seeing an increasing number with the same problem. Seven spot welds from the factory assembly process do not hold over time and break free causing high wear on the components that depend on the factory structural integrity.

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