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Need4Boost
02-11-2004, 05:41 PM
Well I was lurking the web and stumbled across some info on this performance shop out in Japan that is all about nissan cars. Well reading through the article, I came across something that has been bugging me since I read it. the article stated that at the Nissan assembly plant where they build the sr20det & rb motors, the rooms that they are assembled in is exactly at 68 degrees fahrenheit. Well this shop has a room dedicated for storage and assembly for the sr20det and their rb motors. Their room is also set at 68 degrees fahrenheit and they state that they are fairly religious about it.

The article stated that nissan builds motors at this temperature because of the parts slightly expanding contracting if exposed to different temperatures also the tempratures affect the tolerences of the metals. Sure a single part wouldn't make much of a difference but the article stated that when its all the parts it could mean bad stuff.

My question is, does this apply to rebuilding a motor? Enjuku, Secret Services, Heavy throttle, do you guys build motors at a steady temperature or does this not apply to rebuilding a motor. Or anyone else that knows feel free to share.


-Safa

asad
02-11-2004, 05:59 PM
It absolutely applies to rebuilding motors. The thermal contraction and expansion still exists regardless of whether the motor is new or used.

I HIGHLY doubt that any of the guys you mention (nor >99% of the shops in the country) have a temperature-controlled room for rebuilds. Cast iron has a CTE (coefficient of thermal expansion) of 5.7 parts per million per degree F near room temperature; steel is a little higher, stainless steel is higher still, and aluminum is even higher.

I'd say that rebuilds done without the strict temperature regulation work just fine, although 68-degree climate control is, of course, better. At the very least, the shop that does your rebuild should ensure that the temperature stays constant during all of the measuring and machining steps so they don't measure your pistons on a warm day and measure the bore on a cold one and you end up with too much piston-to-wall clearance (for example).

Asad

ICESoft
02-11-2004, 09:52 PM
Where my dad used to work they made aluminum pistons for GM, they used to get calls all the time in the winter when they would do a dock audit and measure the pistons coming in. Then promptly call the foundry and b*tch about the pistons being the wrong size. Problem was the pistons were ice cold from sitting on the dock all night and the measurements they were comparing them to were at room temperature.

Regards,
Benjamin Jennings, MCP
'95 240SX Champagne Gold

wanabe_dorito_esx
02-11-2004, 10:36 PM
Cast iron has a CTE (coefficient of thermal expansion) of 5.7 parts per million per degree F near room temperature; steel is a little higher, stainless steel is higher still, and aluminum is even higher.

Asad



That's why kuah told me to put the alum subframe bushings in the freezer the night before in press them in. Makes sense

NOSTALGIC_HERO
02-12-2004, 12:10 AM
you guys also forget.... if you want to build a motor at 68degrees. your tools must also be calibrated for measurement at that temperature

Need4Boost
02-12-2004, 01:18 PM
so what would you guys say is the best time of the year to get the motor rebuilt? Spring?...not too cold and not too hot


-Safa

Thx247
02-12-2004, 07:17 PM
so what would you guys say is the best time of the year to get the motor rebuilt? Spring?...not too cold and not too hot


-Safa



When its not racing season. =)

NOSTALGIC_HERO
02-12-2004, 08:04 PM
WTF_mate, time doesnt matter. when is time dependent on temp? you build it indoors in a controlled temperature room. you kraiphaid