Main bearings .003 - anyone?
09-30-2015, 05:21 AM
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Re: Main bearings .003 - anyone?
0.003" is too loose. Your rods won't be getting enough oil.
Oil flows from the pump, through the filter, to the main cap girdle, to the main bearings, through the crank, to the rods. If you have too much clearance at the mains they will bleed off too much oil before the rods.
If this was a drag only car with thick oil that never really gets to temp than 0.003" MAY BE fine but I don't have any experience with drag racing engines; just thoughts.
Oil flows from the pump, through the filter, to the main cap girdle, to the main bearings, through the crank, to the rods. If you have too much clearance at the mains they will bleed off too much oil before the rods.
If this was a drag only car with thick oil that never really gets to temp than 0.003" MAY BE fine but I don't have any experience with drag racing engines; just thoughts.
10-01-2015, 05:11 PM
#4
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Re: Main bearings .003 - anyone?
General rule of thumb is .001" of clearance for every 1 inch of journal diameter. Don't know D series engine specs but that's even too much for B series.
10-02-2015, 06:36 AM
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Re: Main bearings .003 - anyone?
10-02-2015, 05:31 PM
#7
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Re: Main bearings .003 - anyone?
Yeah it's a general rule of thumb and seems to hold true to most engines (no aluminum rod 12k rpm crazy ****).
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10-02-2015, 09:16 PM
#8
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Re: Main bearings .003 - anyone?
.003" is too loose for an old Chevy small block, let alone a new-tech engine like a '90+ Honda engine. Oil clearances are based on many factors, and main journal size is way down on the list. Oil passage length, diameter and oil pump volume coupled with crankshaft harmonics and block deflection command the most attention.
A common example illustrating the vast difference between the ".001" per inch of crank main journal diameter" would be the '98-01 Prelude H22A4 engine. The oil clearance on main journal #5 spec is a mere .0006" (yes six tenths of one thousandth) with a crankshaft main journal diameter of 55mm (2.17").
Higher oil viscosity and lower oil temperature during operation would allow one to stray from the factory suggested specs... trending on the larger (looser) side, but this path runs out of road if the engine is brought up to normal operating temperature. Generally speaking, the newer the engine is, the tighter the oil clearances are inside of it... and the easy answer as to why would be the use of thinner viscosity, higher quality base stock/and additive package oils to meet ever-higher emissions standards.
A common example illustrating the vast difference between the ".001" per inch of crank main journal diameter" would be the '98-01 Prelude H22A4 engine. The oil clearance on main journal #5 spec is a mere .0006" (yes six tenths of one thousandth) with a crankshaft main journal diameter of 55mm (2.17").
Higher oil viscosity and lower oil temperature during operation would allow one to stray from the factory suggested specs... trending on the larger (looser) side, but this path runs out of road if the engine is brought up to normal operating temperature. Generally speaking, the newer the engine is, the tighter the oil clearances are inside of it... and the easy answer as to why would be the use of thinner viscosity, higher quality base stock/and additive package oils to meet ever-higher emissions standards.
10-03-2015, 12:12 PM
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Re: Main bearings .003 - anyone?
.003" is too loose for an old Chevy small block, let alone a new-tech engine like a '90+ Honda engine. Oil clearances are based on many factors, and main journal size is way down on the list. Oil passage length, diameter and oil pump volume coupled with crankshaft harmonics and block deflection command the most attention.
A common example illustrating the vast difference between the ".001" per inch of crank main journal diameter" would be the '98-01 Prelude H22A4 engine. The oil clearance on main journal #5 spec is a mere .0006" (yes six tenths of one thousandth) with a crankshaft main journal diameter of 55mm (2.17").
Higher oil viscosity and lower oil temperature during operation would allow one to stray from the factory suggested specs... trending on the larger (looser) side, but this path runs out of road if the engine is brought up to normal operating temperature. Generally speaking, the newer the engine is, the tighter the oil clearances are inside of it... and the easy answer as to why would be the use of thinner viscosity, higher quality base stock/and additive package oils to meet ever-higher emissions standards.
A common example illustrating the vast difference between the ".001" per inch of crank main journal diameter" would be the '98-01 Prelude H22A4 engine. The oil clearance on main journal #5 spec is a mere .0006" (yes six tenths of one thousandth) with a crankshaft main journal diameter of 55mm (2.17").
Higher oil viscosity and lower oil temperature during operation would allow one to stray from the factory suggested specs... trending on the larger (looser) side, but this path runs out of road if the engine is brought up to normal operating temperature. Generally speaking, the newer the engine is, the tighter the oil clearances are inside of it... and the easy answer as to why would be the use of thinner viscosity, higher quality base stock/and additive package oils to meet ever-higher emissions standards.
That .001" per inch of journal diameter comes from Mahle/Clevite. You can find it in the technical section of their bearing catalogs or even online. It is a general rule of thumb as I have run less clearance and I have run more, it just depends on the engine application. Quoting stock clearances for a performance application is just silly.
10-05-2015, 05:35 AM
#11
Re: Main bearings .003 - anyone?
I doubt the B will match up with all the various D's.
10-05-2015, 07:18 AM
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Re: Main bearings .003 - anyone?
I should have been more clear, D16Y series and the D16Z6 have the same diameter bearings as a B-series. These are not the same bearings though....the B-series appeared to be wider and the tangs are in the wrong spot.
10-06-2015, 08:56 AM
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10-06-2015, 08:38 PM
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Re: Main bearings .003 - anyone?
10-07-2015, 07:28 PM
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10-08-2015, 04:17 AM
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Re: Main bearings .003 - anyone?
Does anyone even make high volume pumps for Hondas?
The main downside to increasing bearing clearance is that it will lower oil pressure, but that only means more oil is flowing over the bearing surface, which is a good thing. Manufacturers like Melling make oil pumps that pump a higher volume of oil, which will bring the oil pressure back up with those loose clearances. This is different than just shimming or installing a stiffer bypass spring, which really might only increase peak oil pressure. For example, for the GM LS engines, Melling makes a STD volume 10295 pump, a higher volume 10296 pump, and an even higher volume 10355 pump.
Some of our OHV V8 engines operate at less than 15psig at a hot idle. That's enough to keep the lifters pumped up and it doesn't even trip the low oil pressure light. Once it sees higher loads and higher RPM, oil pressure gets around 50-60psig, which so far has been enough to support over 980whp on pump gas and nitrous.
FWIW, one option I liked to use in order to get the bearing clearance I want and to avoid low oil pressures in order to make customers happy is to use coated bearings. The engine I just built for myself has bearings in it that got me about .0025-.0030" on the mains (2.5588" journals). With the coating (thanks PolyDyn!), the clearance is now .0015-.0021". The tighter clearance from the coating keeps the oil pressure up even with standard volume oil pumps. If the situation arises that the engine needs more clearance (high load/RPM or bad tune), the coating gets wiped away without hurting anything and has minimal affect on oil pressure since the coating is removed where it needs to be, and not around the entire bearing.
The main downside to increasing bearing clearance is that it will lower oil pressure, but that only means more oil is flowing over the bearing surface, which is a good thing. Manufacturers like Melling make oil pumps that pump a higher volume of oil, which will bring the oil pressure back up with those loose clearances. This is different than just shimming or installing a stiffer bypass spring, which really might only increase peak oil pressure. For example, for the GM LS engines, Melling makes a STD volume 10295 pump, a higher volume 10296 pump, and an even higher volume 10355 pump.
Some of our OHV V8 engines operate at less than 15psig at a hot idle. That's enough to keep the lifters pumped up and it doesn't even trip the low oil pressure light. Once it sees higher loads and higher RPM, oil pressure gets around 50-60psig, which so far has been enough to support over 980whp on pump gas and nitrous.
FWIW, one option I liked to use in order to get the bearing clearance I want and to avoid low oil pressures in order to make customers happy is to use coated bearings. The engine I just built for myself has bearings in it that got me about .0025-.0030" on the mains (2.5588" journals). With the coating (thanks PolyDyn!), the clearance is now .0015-.0021". The tighter clearance from the coating keeps the oil pressure up even with standard volume oil pumps. If the situation arises that the engine needs more clearance (high load/RPM or bad tune), the coating gets wiped away without hurting anything and has minimal affect on oil pressure since the coating is removed where it needs to be, and not around the entire bearing.
10-08-2015, 04:23 AM
#17
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10-08-2015, 04:30 AM
#18
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Re: Main bearings .003 - anyone?
Does anyone even make high volume pumps for Hondas?
The main downside to increasing bearing clearance is that it will lower oil pressure, but that only means more oil is flowing over the bearing surface, which is a good thing. Manufacturers like Melling make oil pumps that pump a higher volume of oil, which will bring the oil pressure back up with those loose clearances. This is different than just shimming or installing a stiffer bypass spring, which really might only increase peak oil pressure. For example, for the GM LS engines, Melling makes a STD volume 10295 pump, a higher volume 10296 pump, and an even higher volume 10355 pump.
Some of our OHV V8 engines operate at less than 15psig at a hot idle. That's enough to keep the lifters pumped up and it doesn't even trip the low oil pressure light. Once it sees higher loads and higher RPM, oil pressure gets around 50-60psig, which so far has been enough to support over 980whp on pump gas and nitrous.
FWIW, one option I liked to use in order to get the bearing clearance I want and to avoid low oil pressures in order to make customers happy is to use coated bearings. The engine I just built for myself has bearings in it that got me about .0025-.0030" on the mains (2.5588" journals). With the coating (thanks PolyDyn!), the clearance is now .0015-.0021". The tighter clearance from the coating keeps the oil pressure up even with standard volume oil pumps. If the situation arises that the engine needs more clearance (high load/RPM or bad tune), the coating gets wiped away without hurting anything and has minimal affect on oil pressure since the coating is removed where it needs to be, and not around the entire bearing.
The main downside to increasing bearing clearance is that it will lower oil pressure, but that only means more oil is flowing over the bearing surface, which is a good thing. Manufacturers like Melling make oil pumps that pump a higher volume of oil, which will bring the oil pressure back up with those loose clearances. This is different than just shimming or installing a stiffer bypass spring, which really might only increase peak oil pressure. For example, for the GM LS engines, Melling makes a STD volume 10295 pump, a higher volume 10296 pump, and an even higher volume 10355 pump.
Some of our OHV V8 engines operate at less than 15psig at a hot idle. That's enough to keep the lifters pumped up and it doesn't even trip the low oil pressure light. Once it sees higher loads and higher RPM, oil pressure gets around 50-60psig, which so far has been enough to support over 980whp on pump gas and nitrous.
FWIW, one option I liked to use in order to get the bearing clearance I want and to avoid low oil pressures in order to make customers happy is to use coated bearings. The engine I just built for myself has bearings in it that got me about .0025-.0030" on the mains (2.5588" journals). With the coating (thanks PolyDyn!), the clearance is now .0015-.0021". The tighter clearance from the coating keeps the oil pressure up even with standard volume oil pumps. If the situation arises that the engine needs more clearance (high load/RPM or bad tune), the coating gets wiped away without hurting anything and has minimal affect on oil pressure since the coating is removed where it needs to be, and not around the entire bearing.
Years ago I was comparing a non vtec oil pump and a vtec oil pump. The non vtec IIRC had a thicker gear by a couple mm, which I would assume create more volume. Can't remember the gear tooth count on both.
I had some Calico coated bearings for my build but they turned out to be too tight by almost .001" Got some ACL race bearings that give me an extra .001. Sucks cause I kinda wanted to give the bearing coatings a try..
10-08-2015, 05:50 AM
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Re: Main bearings .003 - anyone?
That thicker gear should indicate a higher volume of flow. That's basically what the mellings do, thicker georotor set and/or higher lobe count.
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