Moderator
Some hi-po race engines are as wide as 0.0035". Very narrow clearances (in the 0.0020" or less range) can be used if the parts have small tolerances (run out and taper on the crank journals, etc.) and the assembly is meticulous. I think this primarily in engines intended to run a very long time between rebuilds. Hi-po race engines may have small component tolerances, but wider clearances are selected to avoid metal to metal contact when parts deflect under extreme load.
Besides the "bigger is better": concept and that "high-volume" sounds cool, I think the wide clearances on race engines is where the myth of the HV oil pump started. You NEED a HV pump to maintain a good oil film with wide bearing clearances. But that doesn't mean you need it for an engine assembled "normally" and it takes more power to drive it. Of course, if you read on this site you ought to know already about HV pumps and stock pans. For those who have not seen that already, I recommend a search but will give the Cliff's Notes version.
DO NOT USE A HV PUMP AND A STOCK OIL PAN ON AN LT1.
Rich
Besides the "bigger is better": concept and that "high-volume" sounds cool, I think the wide clearances on race engines is where the myth of the HV oil pump started. You NEED a HV pump to maintain a good oil film with wide bearing clearances. But that doesn't mean you need it for an engine assembled "normally" and it takes more power to drive it. Of course, if you read on this site you ought to know already about HV pumps and stock pans. For those who have not seen that already, I recommend a search but will give the Cliff's Notes version.
DO NOT USE A HV PUMP AND A STOCK OIL PAN ON AN LT1.
Rich
Registered User
when i rebuild my engine, it will be a 355 and my clearance will be .002" or very close to it.
i dont plan on hitting anywhere near 7k though..i'm thinking around 6200 for street/track use will be fine for me.
i dont plan on hitting anywhere near 7k though..i'm thinking around 6200 for street/track use will be fine for me.
Moderator
Quote:
i dont plan on hitting anywhere near 7k though..i'm thinking around 6200 for street/track use will be fine for me.
Be careful if you decide to make it that close. You need to check each journal and bore for roundness, taper, concentricity, bore size, etc. Why do you want is so tight? Planning on driving it 200,000 miles Originally Posted by Severous01
when i rebuild my engine, it will be a 355 and my clearance will be .002" or very close to it. i dont plan on hitting anywhere near 7k though..i'm thinking around 6200 for street/track use will be fine for me.
Seriously, there is VERY LITTLE margin for error with what you are planning. If you do go that tight, use a thin oil like a 5W-20 or a 0W-20 if it's going to see cold weather.I am not a pro, but I have built a few motors over the years and I was taught by a pro. I look for 0.0025-0.0030" and call it good.
Rich
Registered User
Quote:
Seriously, there is VERY LITTLE margin for error with what you are planning. If you do go that tight, use a thin oil like a 5W-20 or a 0W-20 if it's going to see cold weather.
I am not a pro, but I have built a few motors over the years and I was taught by a pro. I look for 0.0025-0.0030" and call it good.
Rich
Originally Posted by rskrause
Be careful if you decide to make it that close. You need to check each journal and bore for roundness, taper, concentricity, bore, etc. Why do you want is so tight? Planning on driving it 200,000 miles Seriously, there is VERY LITTLE margin for error with what you are planning. If you do go that tight, use a thin oil like a 5W-20 or a 0W-20 if it's going to see cold weather.I am not a pro, but I have built a few motors over the years and I was taught by a pro. I look for 0.0025-0.0030" and call it good.
Rich
Listen to Rich.
Registered User
Rods AND mains?