Engine Building Services at DBTuned.
08-14-2010, 04:15 PM
#32
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I haven't measured internal engine components during use.
The question was asked as you stated that your clearances allow for cooler temps.
Obviously, for you to make this statement, you must have taken some "before" and" after" temperature readings of the bearings.
But it appears that you didn't do this, as all you did was measure oil temps.
What were the oil temps with the different clearances?
BTW, our arts are measured by the various machine shops that we use and plastigage is used during final assembly.
I've seen starrett, fowler, and mitutoyo dial bore gages, OD mics, ID mics used.
The question was asked as you stated that your clearances allow for cooler temps.
Obviously, for you to make this statement, you must have taken some "before" and" after" temperature readings of the bearings.
But it appears that you didn't do this, as all you did was measure oil temps.
What were the oil temps with the different clearances?
BTW, our arts are measured by the various machine shops that we use and plastigage is used during final assembly.
I've seen starrett, fowler, and mitutoyo dial bore gages, OD mics, ID mics used.
08-14-2010, 04:22 PM
#33
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Another concern about greater clearances is oil whirl/oil whip.
This occurs when a resonance frequency is reached and sustained in "extreme conditions".
The lubricating oil gets whipped up and looks like that picture you posted on you baffled oil can thread.
This occurs when a resonance frequency is reached and sustained in "extreme conditions".
The lubricating oil gets whipped up and looks like that picture you posted on you baffled oil can thread.
08-14-2010, 04:51 PM
#34
I haven't measured internal engine components during use.
The question was asked as you stated that your clearances allow for cooler temps.
Obviously, for you to make this statement, you must have taken some "before" and" after" temperature readings of the bearings.
But it appears that you didn't do this, as all you did was measure oil temps.
What were the oil temps with the different clearances?
BTW, our arts are measured by the various machine shops that we use and plastigage is used during final assembly.
I've seen starrett, fowler, and mitutoyo dial bore gages, OD mics, ID mics used.
The question was asked as you stated that your clearances allow for cooler temps.
Obviously, for you to make this statement, you must have taken some "before" and" after" temperature readings of the bearings.
But it appears that you didn't do this, as all you did was measure oil temps.
What were the oil temps with the different clearances?
BTW, our arts are measured by the various machine shops that we use and plastigage is used during final assembly.
I've seen starrett, fowler, and mitutoyo dial bore gages, OD mics, ID mics used.
I have seen up to 20* variance in oil temperature as well as more consistent oil pressures under heavy use with our spec and recommended oil.
We only use one machine shop for consistency and they do all the measurements. We then use plastigage in house as well as a bore gauge to verify all measurements at the time of assembly.
-- Ed
08-14-2010, 04:53 PM
#35
-- Ed
08-14-2010, 05:12 PM
#38
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I have no idea what the upper limit is for "stock spec" built engines, but several engine builders and race teams pushing high 600 crank horsepower seem to have have no issues with stock spec clearances.
08-16-2010, 08:35 AM
#41
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Looser tolerance = hotter or cooler oil?
Was your data gathered on the same car/mods with two different engines on the same day?
What was the methodology of this research?
We use a German brand true synthetic motor oil in 5-40 and recommend a 10-40 or 20-50 at the track.
But, most customers just use the 5-40 all the time with no failures to date.
08-16-2010, 10:05 AM
#42
Can you clarify this for us?
Looser tolerance = hotter or cooler oil?
Was your data gathered on the same car/mods with two different engines on the same day?
What was the methodology of this research?
We use a German brand true synthetic motor oil in 5-40 and recommend a 10-40 or 20-50 at the track.
But, most customers just use the 5-40 all the time with no failures to date.
Looser tolerance = hotter or cooler oil?
Was your data gathered on the same car/mods with two different engines on the same day?
What was the methodology of this research?
We use a German brand true synthetic motor oil in 5-40 and recommend a 10-40 or 20-50 at the track.
But, most customers just use the 5-40 all the time with no failures to date.
Data was gathered on a couple cars with nearly identical setups under identical conditions. The cars with a slightly looser spec saw more consistent oil and coolant temperatures as well as more consistent oil pressures under heavy track use. This is by no means a perfect test, but gave us some good data in a relatively practical approach.
Why do you recommend a 10-40 rather than a 5-40 at the track?
What's the most power you've achieved on any of your built engines that see track time? How much track time have these seen? What's the most amount of track time any of your built engines have seen?
-- Ed
08-16-2010, 12:20 PM
#43
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Data was gathered on a couple cars with nearly identical setups under identical conditions. The cars with a slightly looser spec saw more consistent oil and coolant temperatures as well as more consistent oil pressures under heavy track use. This is by no means a perfect test...,
Can you quantify "consistent"?
Did you see a decrease in oil temps on motors running your spec'ed clearance?
Because it works.
I don't know...some customers go 1 track event every month, some hit the tracks every weekend.
08-16-2010, 08:43 PM
#44
This being said, I've also seen motors from other builders with overly loose clearances that had a hard time maintaining oil pressure under extreme heat even with a 50 weight oil. I would imagine such a spec would be more appropriate for a very high hp drag race motor that will not see sustained heat as much. The point is that there is an appropriate spec for every application. It all depends on what the customer is going to do with the engine.
Because it works.
. Could you explain why you believe a 10-40 oil would work better on the track than a 5-40? -- Ed
08-16-2010, 09:59 PM
#45
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Huh? That seems to defy the basics of thermodynamics.
[
...The tighter clearance motors seemed to have oil temps rise (up to 20*) and pressures drop through a 20 minute session.
This being said, I've also seen motors from other builders with overly loose clearances that had a hard time maintaining oil pressure under extreme heat even with a 50 weight oil. I would imagine such a spec would be more appropriate for a very high hp drag race motor that will not see sustained heat as much. The point is that there is an appropriate spec for every application. It all depends on what the customer is going to do with the engine.
That doesn't sound very scientific either. Could you explain why you believe a 10-40 oil would work better on the track than a 5-40?
-- Ed
This being said, I've also seen motors from other builders with overly loose clearances that had a hard time maintaining oil pressure under extreme heat even with a 50 weight oil. I would imagine such a spec would be more appropriate for a very high hp drag race motor that will not see sustained heat as much. The point is that there is an appropriate spec for every application. It all depends on what the customer is going to do with the engine.
That doesn't sound very scientific either
. Could you explain why you believe a 10-40 oil would work better on the track than a 5-40? -- Ed
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