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New crankshaft?
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Old 02-27-09, 06:16 AM   #1
chchart
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Default New crankshaft?

First off I am a noob and have little mechanical experience. Some explanations in this thread may not be the right technical terms but I will try to explain my situation as best I can.

I have a 2005 S203 (JDM) bought used last year. The previous owner had the following mods installed:
Cosworth Longblock with all Cosworth internals except for the stock STI crankshaft
Cosworth High Volume Oil Pump
APS S/R 57 Turbo
APS FMIC
APS 70mm intake
APS Headers
APS Fuel rails with Deatschwerks 850cc injectors
Process West Oil Cooler
Ecutek tuned for Gasohol (E20) 95 octane

I was having some oil pressure problems (I have another thread about this) and could not find the source of the problem. So I decided to take out the engine and take a look inside. The engine is only 1 year old (8,000 miles) but with about 10 track days.
When we opened up the engine we saw alot of "burnt oil residue" around the engine block. The pistons and rods were fine. There was also alot of "grayish color" residue on the valves and spark plug head. The valves themselves were fine except for this residue that was subsequently cleaned off.
The mechanic suspected the following:
1) There was insufficient oil to the engine which may have caused the oil to be burnt and residue. This may be due to running the car hard with not enough oil in the engine. Oops.
2) The residue on the valves and spark plug may be due to the Ethanol content in the Gasohol.
This may be the cause of the low oil pressure as the oil is losing its viscosity when coming in contact with the residue. I have no idea if this is possible or not? Any experts care to chime in whether this could be the cause of my oil pressure problems?

Onto the subject of the post. When we inspected the crankshaft, there was a small ring on the shaft most likely caused by abrasion. To my untrained eye, it looked like a small scratch going all the way round the shaft. This is only on 1 area of the shaft. The rest of the crank was fine.
The mechanic said that the crankshaft should be replaced. Is this correct? If so, is there any benefit to go for a billet crank in terms of engine longevity and performance? I don't mind paying for a billet crank but am worried if the same problem (low oil pressure) will cause damage to the new crank again.
Any help is appreciated.
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Old 02-27-09, 03:58 PM   #2
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Default Re: New crankshaft?

At your power level a brand new stock crank would be more than enough.

And yes you should replace it if your mechanic thinks so as they arent that expensive
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Old 03-05-09, 04:15 PM   #3
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Default Re: New crankshaft?

Billet Crank ftw! You'll be able to rev higher not to mention the reliability factor. If you go stock I would recommend you cryo treat it
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Old 03-05-09, 04:32 PM   #4
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Default Re: New crankshaft?

I doubt you will ever reach the power levels that will be too much for a stock crank.
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