Oil pumping volume beyond engine needs?

Hope DynoDave still checking in, as may be only one who knows what I seek, excess oil flow to tap for piston oil jets. Question, about how much oil is bypassed recycled at the pressure relief - so bypass might be sent to oil jets, after some rpm and PSI reached? How much oil is being pumped and used @ 6000 to 7000 rpm?

Warm the motor up and put a very strong spring in the pressure relief valve and you will probably find that with the average pump and hot oil nothing is returned. You will know because the strong spring will not increase your hot oil pressure. Jim

hobot said:

How much oil is being pumped and used @ 6000 to 7000 rpm?

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"26 [Imperial] gallons an hour at 6,000 RPM" According to the late John Hudson.

(31.2 US Gals/118.19 ltrs.)

Alrighty L.A.B. my Commando mood swing has swung upward. Prior estimates I'd read of what is actually supplied through engine was 13 gal hr @ 6000, 10 to crank, 3 to head. For my brain that's rather under a quart-liter per min consumed. That implies anything over that is being bypassed cycled.

Your post on late Mr. Hudson's report of pump capacity of 30 US gal an hour @ 6000 rpm implies about 17 gal/hr excess oil bypassing. Cool. 17gal/60min = .28 gal/min or over a quart-liter per min excess. Divided in two that flow gives each jug .14 gal a min or over a pint a min each. Dang, just might be enough to matter on piston crown temps. Oil jets will allow that much more oil through crank case to carry a bit more heat off generally too.

Extrapolating above to 7000 rpm gives 35 gal/hr oil pumping. Assuming engine doesn't require much more oil @ 7000 than 6000, say 14 gal/hr instead of 13, implies 21 excess gallons available by red line. 21/60 = .35gal/min, split gives .175 gal per jug or 2/3rd a qt per min each piston hot spot, cool.

I could use some help to decide what threshold to set jets' valve to open, I'm guessing 50 PSI? Should I think about a different bypass spring setting?

Jim, I'm still in catch up mode to real Nortoneers, so I don't comprehend your remark except to expect a strong enough spring the oil pump can't open bypass valve so all oil goes through engine resistance and pressure shoots up. How would the extra strong spring educate me or assist Ms Peel from blowing in front of the wrapped out 1198 and others? Modern hot shots don't baby their engines so why should Peel, as she ain't really a vintage frail Norton no more.

hobot said:

Alrighty L.A.B. my Commando mood swing has swung upward. Prior estimates I'd read of what is actually supplied through engine was 13 gal hr @ 6000, 10 to crank, 3 to head. For my brain that's rather under a quart-liter per min consumed. That implies anything over that is being bypassed cycled.

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John Hudson does carry on to say (in his video) that "13 [Imp.] gallons pass through the big ends and 2 or 3 [Imp.] gallons goes to the valve gear, but I can't see that an excess of 10 Imp. gallons would be blown out of the OPRV especially when the engine oil was hot-so Jim is probably right.

Pump wear may also significantly reduce output?

John Hudson does carry on to say (in his video) that "13 [Imp.] gallons pass through the big ends and 3 [Imp.] gallons goes to the valve gear, but I can't see that an excess of 10 Imp. gallons would be blown out of the OPRV especially when the engine oil was hot-so Jim is probably right.

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Ugh, mood was bumped up to read the units are Imp gallon, yea, then dropped again to lean no one seems to know what happens to the difference of what engine can accept from the pump and what the efficient powerful hydraulic gear pump of incompressible oil must be pumping delivering somewhere to prevent oil PSI spikes that blow hoses off : ( [Its familiar life style now ok]

Jim remarks confuse me, guess he assumes I'm competent as you or him. sure.
I thought strong bypass spring gave higher oil PSI before relief through bypass path. Why would a super strong spring not just force pump to keep increasing oil pressure till it squirted out enough inside engine to stop the increase? 100 PSI is common on average cold starts I read but that also where most gauges stop so may spike above that till thin enough to squirt/fling inside out faster.

I'm on mission to embarrass the moderns, already know I can run circles around em and plant more power in 45+ degree turns, just not the sprints to ungodly speeds over the ton. Scratching at straws to have a chance, detonation is main booga boo when I turn up the fire. Help me get away with it please.

hobot said:

Jim remarks confuse me, guess he assumes I'm competent as you or him. sure.
I thought strong bypass spring gave higher oil PSI before relief through bypass path. Why would a super strong spring not just force pump to keep increasing oil pressure till it squirted out enough inside engine to stop the increase? 100 PSI is common on average cold starts I read but that also where most gauges stop so may spike above that till thin enough to squirt/fling inside out faster.

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When the oil is cold, just about any worn pump will make more than enough pressure to blow the OPRV, however once the oil is hot it's also much thinner so the oil escapes far quicker from between the bearing surfaces and the pressure from the rather low delivery rate (when compared to many modern pumps) oil pump will eventually drop to a point where it is often lower than the amount needed to blow the OPRV, so no matter how strong the OPRV spring, it won't help to increase oil pressure.

By way of a comparison, the Eaton type oil pump as fitted to a 70's BMW airhead twin can deliver 308 Imp gals. per hour at 6000 RPM (although the BMW pump does have to supply two plain main bearings and a cam bearing as well as the big ends and valve gear).

Appreciate the hand holding on this. Clears up Jim's remarks, implying not enough oil pump to begin with to keep up with what engine can squirt out inside, let alone to oil jets enough to matter a whitworth. Ugh. Only way my brain can reconcile the data is that Mr. Hudson report is with no load on pump out let while the 13 gal amounts is all the pump can push through engine @ 6000. So means I can't continue to day dream on an elegant oil jet supply plumbing and should foregetaboutit or plan on 2 electric pumps - if testing reveals more heat dumping needed to survive. Water injection to both cool and tame detonation, while adding power is what I'm really betting on to prevent blow up melt downs.

hobot said:

Hope DynoDave still checking in, as may be only one who knows what I seek, excess oil flow to tap for piston oil jets. Question, about how much oil is bypassed recycled at the pressure relief - so bypass might be sent to oil jets, after some rpm and PSI reached? How much oil is being pumped and used @ 6000 to 7000 rpm?

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Increasing the oil supply for piston oil jets - i.e. via the conrod bleed hole, means you will have to either speed up the delivery or increase the oil gallery size. That means either modifying the pump driving gear or increasing the aperatures in the bigends and in the con-rod. At present all the oilways are sized to a volume / flow rate. To get more to the con-rods means taking it away from somewhere else such as the rocker feed.

You could for example, revert to the Triumph / BSA method of low pressure return supply to the rockers and divert the pressure feed to the crank end. I guess if racing Commando motors have not altered the stock set up, there's little point in risking drilling holes in motor components for no real benefit?

Mick

hi hobot,i can see what you,re trying to do but bear in mind,significantly increasing feed pressure is very likely to turn the crank oil seal inside out with disastrous results

chris plant said:

hi hobot,i can see what you,re trying to do but bear in mind,significantly increasing feed pressure is very likely to turn the crank oil seal inside out with disastrous results

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I always looked for my bike to do that, decided it must just be a problem with some type of seals. Jim

ML, sorry we have a failure to communicate, Ms Peel will not have rod oil jets and they do nothing but take some rod shell oil wedge lubrication away. Racers block them off and they were a stop gap feature for siezures that turned out to be bad piston batch but rods remained the hole, like horses with a residual usless toe patch a foot off the ground. Research shows it takes over a liter/min to cool piston our size 100' F. Bad boy engines up to 3 gallon a min per jug, ugh.

ML your idea to tap head supply for jets and low pressure return flow for head supply has good merit to me to stew on a while. But on second thought its not really enough for effective piston jets, ugh.

Chris I've no intention to reduce oil press - instead I'd be lowering it by giving oil another path to escape. My worry is oil jets would steal too much at low rpm, so plan was oil jets only flow when oil pump hits a decent PSI threshold, then hope the pump can keep pressure up enough for anything but the head. tickle. I understand the crank spin fling out can pull on the oil supply fed it.

Chris, what "engine oil seals" are there to 'blow out" ??? Certainly not the main bearings as crank case volume can't get much over ambient d/t breather and with breather check valve the pressure is lower than outside. Surely not the oil pump nipple trapped and clamped on both sides. No way valve seal stressed by oil pump. About all I can imagine, or seen blow out are the rocker spindle cover seals. I can dream about pumping enough to blow oil out, but then I wake up.

Jim, you must be taking a mental day off or pre April Fooling us playing along there are seals the oil pressure can blow through. Maybe some weep past oil pump base gasket, but so what? I think I remember your saying you got case pressure so low it sucked the main seals inward, but no connection to oil pumping I can conceive.

Last resort would be electric pump from OIF tank to jets then another pump to return it to OIF. Trick there is finding a proper size/capacity off the shelf pump. Not on top of my priority list - yet.

Yet... I am foggy on oil paths into-out of OPRV, but might be educational to tap it to outside and watch what is spraying out beyond what engine takes.
Would this fairly easy to do? Would be handy to have a switch to trip in braking and apex zones in some chases I might get in.

The seal that can blow is the seal in the timing chest cover that feeds oil to the crank. I have heard that some seals available years ago had the tendency to invert the lip if the engine was revved when cold or if the oil pressure relief spring was shimmed too high.

But with the custom oil pump in my bike I see 60 psi hot on the road and 100 psi at idle cold. If you rev it cold it will hit 180 psi and I have never inverted the seal. It's just the standard seal from Andover. Jim

OOHHHhhh. that oil seal, darts, I must of blocked it out my mind as last one closely examined had 1/3 the surrounding boss blasted out by over rev crank flex, ugh. Good to know how good a good seal can hold.

Pray tell, what's a Comstock oil pump got that rest the world missing out on?

hobot said:

OOHHHhhh. that oil seal, darts, I must of blocked it out my mind as last one closely examined had 1/3 the surrounding boss blasted out by over rev crank flex, ugh. Good to know how good a good seal can hold.

Pray tell, what's a Comstock oil pump got that rest the world missing out on?

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Aluminum housing, tight clearances, a .062 wider pressure gear and .125 wider scavenge gear. I built that after I installed the feed line for the cam and found that even with a .015 jet in the line I couldn't build enough oil pressure to move the gauge off the peg when it was hot. Jim

Hi Hobot,
Just a side note, but.......
In John Hudsons notes he comments on the use of an oil pressure gauge on the Commando and passes it off as being useless and more of a worry than anything else. He regards an oil temp gauge as more value. His reasoning was that at high rpm the centrifical force generated by high rpm spinning crank forced oil out of the crank oil gallery through big ends & crank rod oil holes faster than the pump could supply the oil, hence comming down the 'Mountain' at the Isle of Man flat on the tank throttle wide open and against the stop at long distance high speed ( flat strap in top) high engine rpm, the oil pressure as shown on the oil pressure gauge would drop off causing concern to the rider who in turn may be inclined to back off. JH seemed to subscribe to the idea that no oil pressure gauge, no worry, no back off!!!

Point I'm making is about oil pump delivery rate. According to JH, the oil pump delivery rate at full engine rpm for that distance was at or over it's ability / limit.

How this applies to the real world?? I guess for most people the oil delivery rate is ok because how often would a regular Norton owner be in the situation where the throttle was held wide open and the bike was running full revs flat biscuit for that kind of considerable distance.

However, if one was building a super Peel and out challenging modern pocket rockets around the hills of the Ozarks.................

Bob
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