Which 20w60 oil for hot pressure? - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 52 (permalink) Old 06-08-2019, 05:51 AM Thread Starter
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Main Motorcycle: Trident T160 Bobber.
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Which 20w60 oil for hot pressure?

Looking to get a little more oil pressure from my T160 when really hot so want to go from 20w50 to 20w60 so which oil have you found that keeps hot viscosity/pressure best when hot? not interested in oil debates and whether it has high ZDDP content etc just which retains best oil pressure when hot.

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post #2 of 52 (permalink) Old 06-08-2019, 06:10 AM
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Hi,

What oil pressure are you seeing now when hot?

However, given a triple's oil pump and British ambient temperatures, if your bike really has low oil pressure (lower than 10 psi/1000 rpm), you know what's wrong, how to fix it and that a higher-viscosity oil isn't the latter.

Regards,

Stuart
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post #3 of 52 (permalink) Old 06-08-2019, 06:26 AM Thread Starter
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Well the odd thing is that on cold start i get the usual 100+psi and at normal hot temps i see anything from 20psi at 1,000rpm and around 40psi at cruise 2,500-3,000rpm so dont think the mains are that bad (replaced shells about 400 miles ago) but did around 40 mls in hot temps the other day and the pressure went a little too low yes less than 10psi at low idle...using Westway 20w50 semi synthetic and wondering if its not all that at keeping hot viscosity.

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post #4 of 52 (permalink) Old 06-08-2019, 07:51 AM
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Quote:
Originally Posted by StuartMac View Post
Hi,

What oil pressure are you seeing now when hot?

However, given a triple's oil pump and British ambient temperatures, if your bike really has low oil pressure (lower than 10 psi/1000 rpm), you know what's wrong, how to fix it and that a higher-viscosity oil isn't the latter.

Regards,
The often quoted 10 psi per 1000 rpm was originally , at least in the USA, a figure for modifed OHV V8 racing engines. I don't believe it's necessarily meant for street engines. Many engines would not be adequately protected by 30 psi at 3000 rpm when working hard like a loaded truck pulling a grade...it will shorten the life of the bearings..
I'm no expert about Tridents, but John Healy has mentioned, I assume from his actual expereince, that a Trident with less than 75 psi at speed,whatever that speed is, is a thrown connecting rod waiting to happen...

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post #5 of 52 (permalink) Old 06-08-2019, 07:54 AM
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2,500 rpm sounds a bit low for a cruise.
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post #6 of 52 (permalink) Old 06-08-2019, 08:54 AM Thread Starter
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Originally Posted by Truckedup View Post
The often quoted 10 psi per 1000 rpm was originally , at least in the USA, a figure for modifed OHV V8 racing engines. I don't believe it's necessarily meant for street engines. Many engines would not be adequately protected by 30 psi at 3000 rpm when working hard like a loaded truck pulling a grade...it will shorten the life of the bearings..
I'm no expert about Tridents, but John Healy has mentioned, I assume from his actual expereince, that a Trident with less than 75 psi at speed,whatever that speed is, is a thrown connecting rod waiting to happen...
Yeah see those comments about needing 75psi but sorry not convinced as i have been using this engine normally and dont think i have ever seen 75psi when fully hot...maybe at full RPM and high load it could be a problem but having tuned high horsepower car motors that run around 60psi as an absolute maximum with no problems i really cant see why a magic minimum number is needed as the T160 motor is a lot less stressed, to me its more the amount of oil available and the necessity of maintaining a oil cushion regardless of pressure that's paramount....sure pressure helps but its the oil itself that provides the protection.

However i digress and while i knew i would get some whys and wherefores which is not unappreciated but i would like to get some feedback on the oil question.

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Last edited by Tricky-Dicky; 06-08-2019 at 09:18 AM.
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post #7 of 52 (permalink) Old 06-08-2019, 09:41 AM
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Required oil pressure for safe operation varies a lot depending on engine design...Back in the 70's when NASCAR racing still used production based engines. Chevy V8 was reliable at 550 HP at 7500 RPM on 55 psi oil pressure. A Ford V8 required over 90 psi to be reliable in the same situation. The two engines have similar bearing and journal sizes but differences in the oil galleys...
.Many sport bikes spinning over 12,000 rpm on 65 psi oil pressure...So the 10 psi per 1000 rpm doesn't always apply..
Ask Speed Rattle on this site about the connecting rod poking through the case of his T150....
I'm not saying a Trident can't survive on less than 75 PSI at high rpm but it can be marginal perhaps...???

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post #8 of 52 (permalink) Old 06-08-2019, 10:02 AM Thread Starter
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Trouble is various story's and myths arise out of certain circumstances leading to failures and then becoming gospel ...especially in the world of vintage bikes, when i think of some of the old bikes i have had and abused in the past i wonder just how they ever held up....but they did.

When i think back to a Thunderbird/Bonneville hybrid i once had that i used to shim the PRV in order to get the pitiful oil pressure up a bit i wonder how they survived.

I start to think about a 2JZ GTE turbocharged motor with completely std internals with 60K on it running over 700bhp at 6,500 RPM with an oil pressure of just 60psi on a std multigrade oil, most of the time i tend to make comparisons and think twice.

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post #9 of 52 (permalink) Old 06-08-2019, 10:39 AM
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I have the same problem TD and decided for LiquyMoly 10W60 synthoil GT1 ( full synthetic made for BMW M cars ).
Gives me reliable 20psi on hot day in city traffic idle, like going slowly from one crowded crossing to the next.
This is very common situation for me during coming back from spirited rides in the country.
My pressure was always 85 psi max, on cold oil during cold day perhaps it can reach 90.
My cruising pressure varies from 40 to 60 depending on speed and day temperature, but is little higher than 10 psi per 1000 revs.
With this oil is 5 psi higher, so 45 - 65 on fully hot oil.
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post #10 of 52 (permalink) Old 06-08-2019, 10:54 AM
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IMHO going to a higher viscosity oil won't solve the problem.
Here's the difference between a triple and a twin. On a triple you have plain bearings holding the crank in the center case. These are the first fed by oil then the rod bearings. If they are worn as shown by low oil pressure the rod bearings are going to be starved. Where as on a twin the feed is directly to the rod bearings. So even if they are worn they are still receiving full volume.
Factory says at least 75 psi at cruising. Just got back from a ride on my t150, 80 degrees F, running oil pressure 80-90 psi at 4000 rpm. Idle 35-40 at 1200. Doesn't hurt to set the idle a bit high. 800 miles on newly rebuilt bottom end. Big D in Dallas did the crank and supplied the bearings.
Did you have the crank turned when you did the mains?

Htown16, Houston, Texas
1978 T140E Bonneville, 1974 Trident, 1972 Commando, 1971 Commando
1974 Commando, 1970 BSA Thunderbolt, 2004 XL 1200R Sportster
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If its not alright, its not the end.

Last edited by htown16; 06-08-2019 at 11:10 AM.
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