Loose tolerance engine

Yuk

Messages
883
Location
Edmonton, AB Canada
It is often said on the site that loose tolerance engines may benefit from a W50 oil and tight tolerance engines will do better with a W30. How do i know if my engine has tight or loose tolerances? The engine in question (a 1999 VW/Audi 1.8T) has used for most of its, 133,000 km, life Castrol Syntec 5W50 and has never needed make up oil. Not even a drop. Currently, the engine is 1000 miles in on an Auto-Rx rinse with Penzoil 5W30 and still has used no oil. Does this mean I have a tight engine?
 
Messages
23,591
I wanted to know the same thing in regard to my 2.8 Audi motor. A few people have claimed the 2.8 was on the loose side and a candidate for thicker (5W-40, 15W-50) oil. I even posted the bearing clearances on this forum, but nobody told me if those numbers hinted at a "loose or tight engine." [ August 23, 2003, 06:42 PM: Message edited by: moribundman ]
 
Messages
43,676
Location
'Stralia
A general "rule of thumb" that I've read many times for journal bearing clearances in engines was 1 thou per inch of diameter. Holds very close for many engines, built over many decades. I checked the design bearing clearnaces for the turbines at work a few years ago (one designed in the late 50s, one designed in the late 70s. The 10" bearings have 10 thou. The 12" bearings have 12 thou. No prizes for guessing what the 14 incher bearings have.
 
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23,591
Here are the clearances for the VW/Audi 1.8T and the 2.8 (12v and 30v): Main Bearing Clearance: 1.8T ---> 0.0008 to 0.0023" (0.02 to 0.06 mm) 2.8 ---> 0.0007 to 0.0018" (0.018 to 0.045 mm) Connecting Rod Bearing Oil Clearance: 1.8T ---> 0.0004 to 0.0024" (0.01 to 0.06 mm) Piston Ring Side Clearance: 2.8 ---> 0.0006 to 0.00244" (0.015 to 0.062 mm) Connecting Rod Side Clearance (all engines): 0.0020 to 0.0122" (0.05 to 0.31 mm) Piston Ring End Gap: 1.8T top compression ring ---> 0.0079 to 0.0157" (0.20 to 0.4 mm) second compression ring ---> 0.0079 to 0.0157" (0.20 to 0.4 mm) oil control ring ---> 0.0098 to 0.0197" (0.25 to 0.50 mm) 2.8 top compression ring ---> 0.014 to 0.020" (0.35 to 0.50 mm) second compression ring ---> 0.020 to 0.028" (0.50 to 0.70 mm) oil control ring ---> 0.0098 to 0.0197" (0.25 to 0.50 mm) Piston Ring Side Clearance: 1.8T top compression ring ---> 0.0023 to 0.0035" (0.06 to 0.09 mm) second compression ring ---> 0.0023 to 0.0035" (0.06 to 0.09 mm) oil control ring ---> 0.0012 to 0.0024" (0.03 to 0.06 mm) 2.8 top compression ring ---> 0.001 to 0.003" (0.02 to 0.08 mm) second compression ring ---> 0.001 to 0.003" (0.02 to 0.08 mm) oil control ring ---> 0.001 to 0.003" (0.02 to 0.08 mm) How do those clearances compare to those of other motors? [ August 24, 2003, 05:15 AM: Message edited by: moribundman ]
 

Leo

Messages
911
Location
Australia
In my Nissan SR20DET (1995), serivce manual states Main Bearing Clearance: 0.0002" - 0.0009" (0.004 to 0.022 mm) Connecting Rod Bearing Clearance: 0.0008 to 0.0018" (0.02 to 0.045 mm) Piston Ring Side Clearance: 1.8T top compression ring ---> 0.0018 to 0.0031" (0.045 to 0.08 mm) second compression ring ---> 0.0012 to 0.0026" (0.03 to 0.065 mm) Connecting Rod Side Clearance: 0.0079 to 0.0138" (0.2 to 0.35 mm) There are lots more clearances I could post, but I cant be bothered typing them all out! As you can see, the Nissan SR20DET is a tighter motor all round compared to the Audi which suprises me, and the workshop manual recommends 10W-30 regardless of outside temps. However 10W-40 is the go in my engine, as its modified... (65% more power than std).
 

Yuk

Thread starter
Messages
883
Location
Edmonton, AB Canada
So it looks like Moribundman and I have loose engines compared to Leo's Nissan. Is there an industry average for these figures? Is there any correlation between these figures and oil consumption?
 
Messages
23,591
I get the feeling I posted all the data for nothing. There were people who ASKED me to post those clearances a couple months ago, and I did post them now for the second time. So far we got the blanket statement that all engines have had about the same clearances for the past decades, and we have data on one other make. Well, I can't tell if either one of those engines has loose or tight clearances. I can only see one is tighter than the other... [Roll Eyes] PS: Yuk, what are the clearances in your turbo? I suspect those are kind of important... [ August 24, 2003, 03:24 PM: Message edited by: moribundman ]
 

Yuk

Thread starter
Messages
883
Location
Edmonton, AB Canada
I don't have the figures for the turbo. I'll do some research and find out. I guess the clearance argument is moot then?!? If you don't know constitutes a tight engine then all the debate about heavy vs light weight oil, at least in relation to clearances, has been for not.
 
Messages
2,556
Location
Columbus Ohio
1996-1998 GM "vortec" 5.7 (most people here refer to Gen 1 SBC's as loose clearance engines) Main bearing clearance #1 .0007 to .0021 #2,3,4 .0009 to .0024 #5 .0010 to .0027 connecting rod bearing clearance .0013 to .0035 Piston ring to bore clearance .0007 to .0020 Piston ring side clearance Compression rings (both) .012 to .032 Oil control ring .0020 to .0070 piston ring end gap Top compression ring .010 to .020 2nd compression ring .018 to .026 oil control ring .010 to .030 [ August 24, 2003, 03:51 PM: Message edited by: sbc350gearhead ]
 
Messages
451
Location
Bribie Island, Oz
These are the clearances for my Ford 5.0L Windsor V8 (1995) in metric, from workshop manual. Main Bearing Clearance: 0.01 to 0.05 mm Connecting Rod Bearing Clearance: 0.02 to 0.06 mm Piston Ring Side Clearance: top compression ring 0.051 to 0.102mm second compression ring 0.051 to 0.102 mm Connecting Rod Side Clearance: 0.254 to 0.508
 

Patman

Staff member
Messages
22,012
Location
Guelph, Ontario
quote:
Originally posted by sbc350gearhead: 1996-1998 GM "vortec" 5.7 (most people here refer to Gen 1 SBC's as loose clearance engines) Main bearing clearance #1 .0007 to .0021 #2,3,4 .0009 to .0024 #5 .0010 to .0027 connecting rod bearing clearance .0013 to .0035 Piston ring to bore clearance .0007 to .0020 Piston ring side clearance Compression rings (both) .012 to .032 Oil control ring .0020 to .0070 piston ring end gap Top compression ring .010 to .020 2nd compression ring .018 to .026 oil control ring .010 to .030
Can I safely assume that my 95 LT1 350 engine uses these same clearances?
 
Messages
2,556
Location
Columbus Ohio
quote:
Originally posted by Patman: Can I safely assume that my 95 LT1 350 engine uses these same clearances? [/QB]
I can't say. The LT-1 is a gen 2 engine and is designed to spin to higher rpm and has more power than the vortecs. LT-1 275-305 HP 325-335 ft lbs tq Redline [I dont know] vortec 250-255 HP 330-335 ft lbs tq 5000rpm [ August 24, 2003, 09:29 PM: Message edited by: sbc350gearhead ]
 
Messages
23,591
sprintman, I don't know if others are posting clearances or tolerances. I posted the clearances of my engine, and I skipped the tolerances. [Roll Eyes] [Razz]
 

Leo

Messages
911
Location
Australia
I posted clearances, if anyone wants more info, I will gladly post more. So far, the SR20DET is the tighest engine of these all!!! And I know in europe, 50wts are quite popular in this engine like the M1 15W-50!! Just wondering, is an engine with tighter clearances generally a better built one? This engine is Japanese.. [ August 24, 2003, 11:52 PM: Message edited by: Leo ]
 
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