IOM Le Mans back from Daytona

[rich46]

Hello All,

 

As any of you who are following the IOM Le Mans Moto Guzzi project we have begun the post race look see.  Our focus was on the oiling problems.  I might add that it was by no means terminal but was enough to get the tech boys hands reaching for the meatball flag.

 

So for the most part we found that our outflow lines from the engine may have been larger then the vent from the catch tank and there for causing a slight over-pressure in the catch tank itself.  Here in  lies the reason for this post.

 

Can one of you Guzzi brains explain what the rear hose fitting that comes from the pan does ?  We plumbed the oiling system by copying the plumbing on a 2003 V11.  Now we are wondering if that hose is in fact a drain back line and/or  that there might be a one-way valve in that system that we are missing and should be included on the race bike.  Our oil pressure is fine 80 psi sitting 60 psi on track.

 

We don't mind being wrong once but sure need to get this taken care of prior to Willow Springs in a month.

 

Please,  any advice or information would be a great help.

 

Cheers

Rich

 

Any help would

 

 

[Lucky Phil]

Hello All,

 

As any of you who are following the IOM Le Mans Moto Guzzi project we have begun the post race look see.  Our focus was on the oiling problems.  I might add that it was by no means terminal but was enough to get the tech boys hands reaching for the meatball flag.

 

So for the most part we found that our outflow lines from the engine may have been larger then the vent from the catch tank and there for causing a slight over-pressure in the catch tank itself.  Here in  lies the reason for this post.

 

Can one of you Guzzi brains explain what the rear hose fitting that comes from the pan does ?  We plumbed the oiling system by copying the plumbing on a 2003 V11.  Now we are wondering if that hose is in fact a drain back line and/or  that there might be a one-way valve in that system that we are missing and should be included on the race bike.  Our oil pressure is fine 80 psi sitting 60 psi on track.

 

We don't mind being wrong once but sure need to get this taken care of prior to Willow Springs in a month.

 

Please,  any advice or information would be a great help.

 

Cheers

Rich

 

Any help would

Its  a drain back hose from the frame spine. The crankcase breathes into the spine and from there into the airbox. Any oil that accumulates in the spine can drain back into the cases. No check valve involved. All V11 versions are the same. From the photos of your bike I'm not sure if the catch tank is large enough (if thats it between the carb inlet trumpets) although a Guzzi doesnt have a crankcase breather read valve assembly like a Ducati which helps create a depression in the cases during running. Might be worth considering. If the catch tank has a lot of oil in it then you will probably need a drain back tube. On My TT2 Ducati ( 1980's ópen bell mouth 600 Vtwin) the catch tank vent from the cases also allowed drain back of oil into the cases due to its location on the tank. On big twin you can never have a too large a catch tank. I would also dump the breather filter thing and run a pipe to the rear of the bike uphill with a simple rubber flapper valve on the end.

 

Ciao

[Pressureangle]

Um, my '97 Sport i has two hoses going from the spine to the pan...?

Some engines just don't like being revved up and staying there. In the days of the Daytona H-D 883s, we took the oil pumps from older iron sportsters (-30% volume) and had quart-sized catch cans. Pumping on a common-pin V-twin is enormous. 

Link to pics? Is it carbureted? I was thinking a reed valve and catch can with return in the distributor hole would be nice-if you don't have a distributor. Something at the top of the timing chest would be good too, if it was baffled to keep slinging chain oil away. 

[swooshdave]

Rear hose in the pan is an oil return line. If you are only running a catch tank and not a separator/return you will have big problems. At the Isle of Man this will be terminal. A big Guzzi pushes a lot of oil. You may be able to get away with it in sprint races but anything more than that requires something a little more thought out.

 

You need to fabricate an oil catch tank at least the same volume as engine capacity(1100cc). Inlet should be no smaller than outlet from engine. Outlet of separator should be no smaller than inlet of separator. Oil tank should have an internal dam to catch the oil and have a line returning separated oil to the sump via the fitting at the rear of the sump. Run a line to atmosphere from a high point in the tank.

 

I have raced a Guzzi for 4 hrs straight with this set up so this is informed advice.

No reed valve in your setup to help depressurize the crankcase?

 

 

Sent from my iPhone using Tapatalk

[swooshdave]

 

 

No reed valve in your setup to help depressurize the crankcase?

Sent from my iPhone using Tapatalk

No reed valve. The high volume of the breather takes care of crankcase pressure

 

 

That just helps the pressure out but you don't have anything keeping it from sucking back in.

[swooshdave]

 

 

My understanding is the 'open' system I have does fluctuate but the average pressure will be atmospheric. Any additional pressure caused by blow by will be handled by the breather volume and large inlet size.

 

I'm not an expert. I did a lot of research when I built my bike so all I can say with certainty is that it works. There's barely any oil in the atmosphere pipe, the engine doesn't burn oil and there are no oil leaks even after sustained high rev running (Spa 4hr endurance race).

 

Here's a great article: http://www.voc.uk.com/net/docs/3.5f/3.5-252-15.pdf

 

 

As brillant as Phil Irving was he didn't have access to some of the modern instrumentation we do now. If so I'm sure he would have loved to play around with neutral crankcase pressure.

 

For a racing engine you might be able to squeak out a smidge more power if you put a reed valve close to the crankcase. But if it's working to your satisfaction you probably shouldn't change a thing. The Guzzi configuration is less susceptible to over-pressurization than something like a single or a parallel twin. Those are just giant pumps.

[Pressureangle]

The subject of crankcase pressure has the same voodoo about it as balancing v-twins, quench clearances, and oxygenated fuels. 

Every engine design is different, so each requires a particular vent layout, with the goal in mind-and that goal is a moving target in some engines. 
The Guzzi big block has, by comparison, a huge crankcase volume so pumping losses are far less than something like a H-D Sportster with it's huge flywheels and dry sump, or a modern motocross 4-stroke. For nearly all riding styles, the factory venting is perfectly adequate. 
The theory behind a reed valve is that the overall crankcase pressure is reduced; it is, and with proper design reduced by a lot. Reducing crankcase pressure to a point is good; it reduces piston effort to some degree, but most importantly and sort of in the shadows is the density of the air moving in and out. Denser air carries more oil vapor, mixes more with vaporized and slung oil, and creates a tighter vortex around the crankshaft (I had a friend in Roush's durability lab, who said a v-6 buick at 8000rpm could carry 8 quarts of oil in the crank vortex, starving the pump) 
and has a higher velocity moving through the holes in the breather. Adding the reed valve raises the point pressure a tiny bit, but eliminates entirely the return air; creating a partial vacuum in the case. Lesser pressure in the case facilitates oil return from the top end instead of pumping air upwards through return holes, etc. Splashed oil has less resistance to get where it's going and return to the sump. The crank carries less oil. 
It was found, though, that if pressure falls too much- and that can happen if you work at it- there is less than desired air pressure to push the oil out of the sump and up into the pump. 
A reed valve can never exhaust more air than the minimum crankcase volume when both pistons are down, so it can never overevacuate like a pump or exhaust pitot. It's dead simple, cheap, easy to mount (inline in the hose if necessary) The only real problem is that if you don't baffle it well enough, any oil that gets past it stays past it, and running a non-pressurized return to the sump leaves an open hole and kills the concept.
I designed a crank scraper for my '85 LMIV and started with Ishihara-Johnson but sort of lost track of it when my wife passed. I'll stir that pot up again if it would fit your engine.

[swooshdave]

 

You can see the effect of the reed valve on my Norton. On this model there is a vent off the back of the crankcase, then a very short hose, reed valve and then a long hose back to the oil tank. I drilled a small hole next to the reed to allow any oil that gets stuck up past the reed valve to drain back into the crankcase when it wasn't running. The hole is too small to affect the functioning of the reed valve. If you watch carefully you can see the pulses as the oil is pushed up past the reed. Then as the pressure drops the oil doesn't move as much.

 

The Guzzi is definitely different but Ducatis and BMWs have run reeds so there must be some gains on V or opposed twin.

[Pressureangle]

 

 

You can see the effect of the reed valve on my Norton. On this model there is a vent off the back of the crankcase, then a very short hose, reed valve and then a long hose back to the oil tank. I drilled a small hole next to the reed to allow any oil that gets stuck up past the reed valve to drain back into the crankcase when it wasn't running. The hole is too small to affect the functioning of the reed valve. If you watch carefully you can see the pulses as the oil is pushed up past the reed. Then as the pressure drops the oil doesn't move as much.

 

The Guzzi is definitely different but Ducatis and BMWs have run reeds so there must be some gains on V or opposed twin.

Excellent vid and explanation. The Norton doesn't lend itself well to crankcase venting because it's a close-case dry sump. Is yours a Colorado Norton Works reed, or something you made yourself? (I have a '71 Fastback in the works, apart and researching) The Guzzi has a lot of places to put a vent up high where oil can separate before it reaches the vent- even the stock place isn't bad, but the limitations are obvious. A hosed reed like yours in the distributor hole or I think at the top of the timing chest would be great.

[GuzziMoto]

I did once try a valve in the breather of my Daytona (same basic system) and it caused issues with the return line. I put the one way valve on the line from the crank case to the spine. That dropped the pressure in the cases which caused air to be pulled down the return line, aerating the oil in the cases like a fish tank bubbler. Then I tried moving the one way valve to the atmospheric vent for the spine. That resulted in oil being sucked up from the sump in the return line.

I did try it without a return line, and it worked. But I thought the return line was more important than the negative pressure. So I re-installed the return line.

At that point I gave up on the one way valve and creating a negative pressure in the cases. Perhaps it is do-able, but I got tired of trying. I decided it was more trouble than it was worth.

[swooshdave]

 

 

 

You can see the effect of the reed valve on my Norton. On this model there is a vent off the back of the crankcase, then a very short hose, reed valve and then a long hose back to the oil tank. I drilled a small hole next to the reed to allow any oil that gets stuck up past the reed valve to drain back into the crankcase when it wasn't running. The hole is too small to affect the functioning of the reed valve. If you watch carefully you can see the pulses as the oil is pushed up past the reed. Then as the pressure drops the oil doesn't move as much.

 

The Guzzi is definitely different but Ducatis and BMWs have run reeds so there must be some gains on V or opposed twin.

Excellent vid and explanation. The Norton doesn't lend itself well to crankcase venting because it's a close-case dry sump. Is yours a Colorado Norton Works reed, or something you made yourself? (I have a '71 Fastback in the works, apart and researching) The Guzzi has a lot of places to put a vent up high where oil can separate before it reaches the vent- even the stock place isn't bad, but the limitations are obvious. A hosed reed like yours in the distributor hole or I think at the top of the timing chest would be great.

 

 

Unfortunately a ton of pictures on how to do this on a Norton are locked up on Photobucket (may they rest in hell).

 

I haven't dug into the Guzzi breathing yet but it's been well beat to death on the Norton. For the 71 if you don't have the frame crosstube interference you should use the Comstock sump breather. My brother has it on a 73 850 and it works great.

 

On my 72 for one year only there is a stock breather off the back of the crankcase which makes an ideal location for a reed valve. I'm using the "XS650 Reed Valve" which never came off a XS650, rather is sold by XS650 Mike.

[Chuck]

 

 

Unfortunately a ton of pictures on how to do this on a Norton are locked up on Photobucket (may they rest in hell).

You can get an add on for Chrome and Firefox browsers called, "Photobucket fix" or some such. Download, install, and see those blocked images.

Photobucket can kiss my patootie.

 

[swooshdave]

I did once try a valve in the breather of my Daytona (same basic system) and it caused issues with the return line. I put the one way valve on the line from the crank case to the spine. That dropped the pressure in the cases which caused air to be pulled down the return line, aerating the oil in the cases like a fish tank bubbler. Then I tried moving the one way valve to the atmospheric vent for the spine. That resulted in oil being sucked up from the sump in the return line.

I did try it without a return line, and it worked. But I thought the return line was more important than the negative pressure. So I re-installed the return line.

At that point I gave up on the one way valve and creating a negative pressure in the cases. Perhaps it is do-able, but I got tired of trying. I decided it was more trouble than it was worth.

You actually don’t want negative pressure because of that. Ideally you shoot for neutral pressure.

 

 

Sent from my iPhone using Tapatalk

[swooshdave]

 

 

 

Unfortunately a ton of pictures on how to do this on a Norton are locked up on Photobucket (may they rest in hell).

You can get an add on for Chrome and Firefox browsers called, "Photobucket fix" or some such. Download, install, and see those blocked images.

Photobucket can kiss my patootie.

 

 

http://www.v11lemans.com/forums/index.php?showtopic=20351&p=231393

 

My Photobucket Rescue

[GuzziMoto]

 

I did once try a valve in the breather of my Daytona (same basic system) and it caused issues with the return line. I put the one way valve on the line from the crank case to the spine. That dropped the pressure in the cases which caused air to be pulled down the return line, aerating the oil in the cases like a fish tank bubbler. Then I tried moving the one way valve to the atmospheric vent for the spine. That resulted in oil being sucked up from the sump in the return line.

I did try it without a return line, and it worked. But I thought the return line was more important than the negative pressure. So I re-installed the return line.

At that point I gave up on the one way valve and creating a negative pressure in the cases. Perhaps it is do-able, but I got tired of trying. I decided it was more trouble than it was worth.

You actually don’t want negative pressure because of that. Ideally you shoot for neutral pressure.

 

 

Sent from my iPhone using Tapatalk

 

Actually, there are reasons you want negative pressure in the crank cases. Not a lot, but negative pressure none the less. There is actual horsepower to be had there. But that is not very feasible with a V11, and I am not sure it is worth the effort. On a big V8 it can be a fairly significant amount of horsepower. But on a V11 I doubt you would be able to feel the difference.

Running slightly negative pressure in the crankcases improves ring sealing and reduces pumping losses.