external oil feed for no"s 1 and 2

[rlubikey]

Tony Lindsey-Dean wrote about this in the TSSC comic sometime back in the noughties. I've searched for the article but have been unable to find it. I seem to recall he said there was some obstruction in the gallery which starved the front of the crank and advocated an oil feed as you've described, Lloyd. Of course, I know lots of people have opinions about TLD! Now, if only I could find his article ...

Richard

[Dread Pirate Roberts]

If it is an oil capacity issue maybe the plastic bung part of the dipstick has moved up the stick hence it goes further into the engine so less oil is required to reach the mark? I have no idea what the correct length should be btw.

[Alec]

Hello Richard,

I have my engine apart at the present moment, after about 40,000 (hard) miles and at least half of those miles I had the universally condemned external rocker feed line fitted (Removed only because it gave a slightly smoky idle). The mains are virtually as new and do not need replacing but the big ends are just showing the odd trace of copper so will be replaced. This to me is does not show any inherent design deficiencies in the oil system. The engine by the way is a 2.5 P.I. slightly warmed up.

I see lots of various ideas and some go as far as drilling out the oilways in the block. However the flow is determined by the restriction at the bearing journals and the rocker assembly and the setting of the pressure relief valve. Because there is less restriction in parts of the circuit is unlikely to make any real difference to overall flow. It may be that some of these modifiers are running racing engines and have built them with extra clearances for freer running where extra flow will be needed because of the greater bearing clearances but this does not mean it's beneficial to road engines?

just my thoughts and experience.

Alec

[rlubikey]

Here we go. The cumulative index for "The Courier" failed me, but Google (the web's "Lidless Eye") has delivered. The article was mentioned over on the CT forum's "Le Taxi" thread, and post 54 about half way down has the scanned pages, courtesy of Leon Guyot.

TLD cites Kas Kastner and claims low oil pressure to the front mains over (wait for it) 5000-rpm. Not territory I personally visit very often! Anyway, I knew I'd seen it somewhere. Read it yourselves and come to your own conclusions.

Richard

[Alec]

Hello Richard,

at one point in the article Tony states that as revs increase so does the oil flow. Well that is true as far as the oil pump flow is concerned but that flow does not increase in the galleries, as the higher the engine rpm, the higher the flow through the pressure relief valve. If that were not so the oil pressure would increase with engine speed rather than being a constant.

Oil flow is proportional to oil pressure so I believe his argument is a fallacy?

Alec

[rlubikey]

Alec, yes the pressure regulator should ensure a constant "head" of pressure. However, I think the flow will increase somewhat with rpm. I'm guessing that bearings use more oil at higher revs, partly because friction *in the bearing* will heat the oil going through, and partly because the oil will be warmer anyway if the engine is working hard at high rpm.

I don't totally agree with TLD/Kastner on how much turbulence the shaft cover causes, because I don't believe Triumph wouldn't have measured this themselves during engine development. Compared to the turbulence caused as the oil takes the side-tee to each bearing, I would have thought that a "chicane" type deviation would be minimal. And as you say, both these should be small compared to the bearing back-pressure (assuming they're not totally shot). But Kastner backs his argument with measurements and, assuming he did it properly, that counts for a lot! So what's the flaw in his method?

When the subject was raised, and remembering the article, I was interested to hear what others thought of it. Other "trick mods" have taken a while to be discredited - your rocker feed for example.

Keep up the healthy scepticism!

Richard

[Alec]

Hello Richard,

I didn't bring viscosity into it as it is largely irrelevant to the discussion, yes it is a factor however.

There are a couple of things about Kastner's pressure measurement of the front journal that may need the explanation of a fluids engineer but to run at high revs and, presumably, load with inadequate oil flow would result in a very short bearing life. I don't remember him saying that it was a real problem in practice but he was worried about the oil temperature, although because he put the pressure gauge on number one journal it must have been a consideration?

The other, from an academic point of view, is that for a meaningful experiment the pressure should also be measured at each main bearing journal directly which would require pressure sensing ports drilled directly to each journal. This would be a true scientific test.
What is in the back of my mind is that the big end journals' centrifugal force is 'pumping' the oil through and out of the journals and so would this drop the pressure at the mains journal? As long as there is sufficient flow, rather than pressure would the oil film be maintained?

Alec

PS, part of my scepticism comes for a long time in engineering maintenance and coming across many 'modifications' that were put in place, but so often the reason for the modification was to overcome a fault in the system rather than a deficiency in the original design or installation, i.e. poor maintenance.

[Lloydpiestate]

hi all,

many many thanks for all your replies, very useful.

the oil level is always checked, because of the mountain issue, and i find the need to top up with just a dash about every four months, not bad considering i use the ole girl every day !

perhaps i was jumping the gun assuming an external oil feed was needed, BUT every engine ive ever
stripped, number one shells are always in worse nick than number six ( no 1 worse, no2 a bit better etc etc ), but was that always due to the usual bad maintenance that engines recieve by previous owners, or oil starvation, due to the need for an extra feed, or both ?? i guess we have to make our own conclusions to this topic.

i will check i have a 2000 sump on the engine and will also put my dipstick up alongside a 2.5 one, as for taking the sump off to measure the pick up length, that will have to wait until i have more time.

one thing i didnt consider, that was mentioned, was checking the level before the cooler had time to drain back, as i always check levels when cold, so doing will give a false reading, what a muppet !!!!

i do have a magnetic plug fitted, and as the engine has only done 20k ish, im hoping there shouldnt be to much gunk in the sump, but again, something i hadnt thought about, and another great valid point, and one that i bet most of us dont consider.

thanks again all, im due an oil and filter change soon ( i do them around 4-5 k to be safe ), will let you all know the outcome, but for now i will just top up to about 5mm above the full mark

[Mike Stevens]

Other "trick mods" have taken a while to be discredited - your rocker feed for example.

Has it actually been discredited - I mean with proper scientific reasons? I've had them on previous cars with no detrimental effects. Oil pressure was fine (not affected) and oil flow to the rockers was improved.

I know there's been lots of negative comments on here about external rocker feeds, but I've not seen any real reason except people's thoughts (which are of course valid). One final point. I don't think Chris would sell them if he though they didn't have a net positive effect!

BTW. I don't have one on either the current 2000 or PI!

Cheers,
Mike.

[Alec]

Hello Mike,

" Oil pressure was fine "

That's what I found when I ran mine. Perhaps those that experienced problems had less than ideal oil systems so just tipped it over the edge? I don't see why a little extra flow to the rockers should starve the main oil gallery? Any sound engine must run with the oil pressure relief valve lifted so there is always oil by passing the system back to the sump, i.e. there is extra capacity above that used to lubricate the engine. This is obviously not true at low revs but the load is low also.

Alec