Oil Starvation: No Room Left for Doubt

[twhitaker]

Nogbad,

Your analogy is right on target. However all the Guzzis prior to the V11 have essentially the same sump and the older models seldom if ever exhibit this problem. In my mind the only difference between the old and the V11 is the hole in the top of the strainer. When the oil sloshes to the back this hole is uncovered allowing the pickup tube to slurp in a slug of air.

[Garsdad]

Nogbad,

Your analogy is right on target. However all the Guzzis prior to the V11 have essentially the same sump and the older models seldom if ever exhibit this problem. In my mind the only difference between the old and the V11 is the hole in the top of the strainer. When the oil sloshes to the back this hole is uncovered allowing the pickup tube to slurp in a slug of air.

94518[/snapback]

 

 

I'm guessing that unless a deeper sump also included a longer pickup tube, you would just have a bigger pool of worthless oil at the back of the sump. Do any of the extended sump pans available include a longer pickup, or do they simply increase capacity?

[pete roper]

Just guessing but the earlier, filterless, motors also had a downward poking pick-up but rarely, if ever, suffer from oil starvation BUT, being sensible, none of them accelerate faster than a slug on mandrax so the rearward surge is going to be scarcely more than tidal . We comprehensively trashed a race motor that I'd built using a filterless case which I'd chosen because of the reduced resistance prior to the pump. It cavitated and exposed the pick up on the front straight at Eastern Creek, that cost us two motors that

 

The *early* filtered motors and up to the current Calis the pick up is slightly more rearward and also the pick-up pipe itself is cast into the sump. It picks up from the very bottom of the sump. With the V11 with it's downward poking pick-up there has to be a decent clearance between the bottom of the pipe and the sump itself otherwise it would be too restrictive. Remember, there is no such thing as 'Suck'. The pump doesn't 'Suck' oil out of the sump, all it does is create a low presure area and crankcase pressure working on the surface of the oil pushes it into the pump. Since the pressure inside the case is unlikely to be much above, (At a guess, with good ring seal etc.) 16-18PSI you don't want any major restrictions between the pick-up and the pump. From memory the pick up pipe has little castelated type *legs* on the end of the tube but whether these actually come close to the floor of the sump I haven't a clue

 

Whatever the reason, be it exposure or cavitation, there obviously *is* a problem. Yes you could go all out and build a really ellaborate *real* windage tray with scrapers, screens and the whole banana. It would be hideously expensive and the gains you'd make would, IMHO at least, not be worth the time or expense. What is really needed is something that will prevent the oil migrating away from the pick-up under hard acceleration, the forward position of the pick up means that exposure under heavy braking is less likely as Greg has observed. Any sort of baffle plate should, for a road bike at least, be fairly robust. The reason I used 2mm stainless plate for my earlier ones is because thinner alloy versions are crack prone. There is little point in having wonderful, uninterupted oil pick-up if your end up feeding great chunks of alloy plate around the engine internals! I don't doubt that you could go thinner than 2mm in steel, I just tend to be ridiculously over-cautious with something like this. Te weight penalty isn't that great and lets face it, we are talking Guzzi big-block here, not Racing RGV

 

Pete

[Guest Nogbad]

I'm guessing that unless a deeper sump also included a longer pickup tube, you would just have a bigger pool of worthless oil at the back of the sump.  Do any of the extended sump pans available include a longer pickup, or do they simply increase capacity?

94525[/snapback]

 

I am fairly sure the deep V has an extended pickup arrangement low down, otherwise there wouldn't be much point.

[Skeeve]

Remember, there is no such thing as 'Suck'. The pump doesn't 'Suck' oil out of the sump, all it does is create a low presure area and crankcase pressure working on the surface of the oil pushes it into the pump. Since the pressure inside the case is unlikely to be much above, (At a guess, with good ring seal etc.) 16-18PSI you don't want any major restrictions between the pick-up and the pump.

 

Funny, Carlo Guzzi's engine designs seemed to favor dry-sumps (which are obviously better for an engine in anything expected to wheelie! ); too bad it's a non-trivial matter to "fix" this oversight in Carcano's engine!

 

Whatever the reason, be it exposure or cavitation, there obviously *is* a problem. Yes you could go all out and build a really ellaborate *real* windage tray ... hideously expensive and the gains you'd make would ... not be worth the time or expense. What is really needed is something that will prevent the oil migrating away from the pick-up under hard acceleration ... Any sort of baffle plate should, for a road bike at least, be fairly robust. The reason I used 2mm stainless plate for my earlier ones is because thinner alloy versions are crack prone. There is little point in having wonderful, uninterupted oil pick-up if your end up feeding great chunks of alloy plate around the engine internals! I don't doubt that you could go thinner than 2mm in steel, I just tend to be ridiculously over-cautious with something like this.

 

(emphasis added) It's pretty clear from what everyone has submitted on this topic which has been tossed about on this board over the past 2? 1.5? years that I've been around that a crank scraper isn't needed, and in fact, you could probably get away with a plate that merely isolates the back 1/2 of the sump a la a box w/ the lid shifted halfway off. As Nogbad pointed out, the deep V sump is an excellent/better alternative, since you end up w/ an external oil filter as well, but I don't have a spare five Benjamins laying about unspoken for; a $50 windage plate would be much more acceptable to me. As for the 2mm stainless: I'd think 18ga mild steel would be a workable substitution: we are discussing mounting it in an oil-misted environment, so rusting is right out, and it isn't going to crack for the simple reason that it practically *won't* work harden, being very nearly pure iron [we're talking 1015 steel here folks, the stuff you can heat red hot, plunge into freezing brine, & it still won't crack or much resist being rolled up like a sheet of paper... ] W/ no "scraper" fingers jutting out waiting to get bent & contact rapidly rotating parts, it would just barely qualify as a "windage" tray: maybe we'd be better off calling it a "sloppage sheet?"

 

I need a garage w/ a stronger set of rafters, so I can strap the V11 to the ceiling and drop the pan to work on this idea comfortably...

[pete roper]

I am fairly sure the deep V has an extended pickup arrangement low down, otherwise there wouldn't be much point.

94532[/snapback]

 

The deep 'V' sumps, unless I'm very much mistaken, replace not only the sump plate but also the spacer that the oil cooler thermostat, pick-up and all the other extraneous 'Broad Sump' munt hangs off. It is in effect very similar to the earlier Tonti sumps in that the pick-up is cast into the bottom of the sump and the OPR valve is in one of the cast-in feeds after the front mounted filter. It is heavilly finned and this is supposed to negate the need for an oil cooler but it doesn't have any form of baffle plate betwixt crank and sump, although because of it's design and the fact there is nothing poking *up* high enough from the bottom or hanging down from above to neccesitate holes in the plate building a 'Slopage Plate' (Great description Skeeve ) for the 'V' sump would be a piece of piss.

 

Pete

[Paul Minnaert]

The deep 'V' sumps, unless I'm very much mistakenPete

94554[/snapback]

 

 

No you are not mistaken, this is the inside of my V sump. So what would be needed to make a dry sump?

 

[Guest Nogbad]

I think a dry sump conversion could be done, but you would need an electric scavenge pump.

 

In dry sump motors the oil pump is a double unit. One set of rotors has a low volume and high pressure and feeds fresh oil from a tank to the engine main oil gallery the other set has a higher volume (to ensure the sump is always "dry") with low pressure and simply picks up the used oil and returns it to the tank.

 

As the oil pump in the Guzzi engine is a single unit, an electric pump would be needed to return the used oil to the tank, and you have to find somewhere to put the tank. The Buell uses the swingarm!

 

It would be a lot of trouble to go to and I can't see any real gain. You add weight, the oil tank has to go somewhere (where?) and if the scavenge failed you would have to stop.

[pete roper]

So what would be needed to make a dry sump?

 

94585[/snapback]

 

How insane do you want?

 

You could get a Convert cam and grind the lobes off and either get a convert timing chest and weld on some bosses for the front sub frames to bolt to so it would fit onto the front of your Daytona motor and use the 'Verter pump as a scavenge pump from the dry sump.

 

Drat! Thinking about it it wouldn't work because of all the belts and crap that hangs orr the front of the Hi-Cam timing cover, bugger!

 

Actually I don't know whether the 'Verter pump would have sufficient capacity but it's a great, loony idea! It would also allow you to drop the motor by a couple of inches to lower the C of G but that might make for problems with the driveshaft etc.

 

Do you really want to go here? No I haven't been smoking anything funny

 

Pete

[Guest ratchethack]

How insane do you want?

Only slightly, please.

 

Howzabout going "semi-dry sump" with a simple baffle plate, or is that too easy, cheap, effective, and practical?!

 

Wot a concept, eh?

 

If somebody doesn't get started on a quantity run pretty soon, I'm gonna hafta whittle my own out of 2 mm stainless by hand, and both of my Pals who want 'em are gonna hafta bide their time.

 

No, I don't think this is reasonable behavior, but then it wouldn't be the first unreasonable Guzzi task I took on, either. . . . .

[Paul Minnaert]

How insane do you want?

94598[/snapback]

 

 

Well I always want to know what options there are, and time has proven that I sometimes take other roads.

[Guest Nogbad]

If somebody doesn't get started on a quantity run pretty soon, I'm gonna hafta whittle my own out of 2 mm stainless by hand, and both of my Pals who want 'em are gonna hafta bide their time. 

 

94599[/snapback]

 

All you need to do is draw the thing neatly and take it to a place that has a laser profiler and they will be able to cut it perfectly for you.

 

If you send me your sketch I could even convert it into a CAD file that can be read by these machines.

[Pierre]

I remain convinced a vortex in the oil is snaking its way through the hole in the top of the screen cover alongside the oil pickup tube.

 

I'm sure you guys are familiar with the AccuSump from the car racing world. Unfortunately, the smallest (and simplest) version needs to be mounted vertically and so limits mounting choices on a motorcycle. How about one of you guys using the idea to create a Moto Guzzi specific version? It's a stone simple and absolutely bullet proof answer to short-term (g-induced) oil starvation.

 

just in case anyone here isn't familiar with the product or concept - here's the web site. Click through to the products. Navigate to the "how it works" sections:

http://www.accusump.com/acc_products/acc_units.html

[Ballacraine]

All you need to do is draw the thing neatly and take it to a place that has a laser profiler and they will be able to cut it perfectly for you.

 

If you send me your sketch I could even convert it into a CAD file that can be read by these machines.

94624[/snapback]

 

Might be worth doing a straw poll amongst the Brits on here and see if it is worth commisioning a short batch run?

 

Nige.

[Guest Nogbad]

Might be worth doing a straw poll amongst the Brits on here and see if it is worth commisioning a short batch run?

 

Nige. 

94641[/snapback]

 

Personally, if I was worried about this I would do the V sump conversion. As it is, the V11 is my pottering and touring bike. If I feel berserk, I have the DRY SUMP XB12R to play on.