40 replies to this topic

[NRoshier]

I have found it interesting reading through some old articles on race car design that dry sump systems were considered so problematic (with drain back and initial startup) even up to the late 80's and yet we now seem to have an increasing number of road cars using dry sump systems. What is the difference in layout of the modern road car dry sump system such that it seems to have become so civilised?

[mariner]

I am not sure the use of dry sumps on raod cars is that new since I beleive the Porsche 911 has used a dry sump system since 1964 and one thing the 911 has always been noted for is being a practical everyday car.

Also most bikes have been dry sump.

In both cases the tank is kept fairly high up so there is a safe head of oil to prime the pump.

[McGuire]

Yep, all Harleys are dry sump. Otherwise the flywheels would be beating oil 24/7. Unless I am really senile the SOHC Honda 750 was dry sump for the first year or two as well. Triumph, etc. Most motorcycles. (The plastic side cover on a UJM was a fake oil tank, I suppose.)

The factors mitigating against dry sump for road cars are cost, complexity, and packaging. I'm sure the recent ascendance of dry sumps is due to the prevalence of really wide tires and high cornering rates. With a wet sump there is only so much you can do to prevent oil from standing up in one side of the pan and starving the pickup.

[marchof73]

My old Norton Model 50 was dry sumped,but occasionally would drain it,s oil tank into the sump,usually overnight.
Upon startup it would then pour oil out of the breather pipe and produce enough smoke to hide a battalion of soldiers.
Never could never find a solution to the problem!

In cars dry sump systems generally take a long time to warm up the oil.

Ian

[Bill Sherwood]

Originally posted by mariner
Also most bikes have been dry sump.

Well more like hardly any in fact.
Only Harley (and hence Buell) use it these days that I know of.

[Canuck]

Originally posted by Bill Sherwood



Well more like hardly any in fact.
Only Harley (and hence Buell) use it these days that I know of.

And Indian (both the recently defunct "Gilroy" versions and the going-to-produce-any-day-now-we-promise King's Mountain versions). That said, I'm not aware of any other current production dry sump bikes.

[Ollies930]

Maserati started using a dry sump in the 1970 Ghibli 4.9ss. But most japanese motorcycles use a shared oil supply for engines and transmission(no dry sump).

[McGuire]

Originally posted by marchof73
My old Norton Model 50 was dry sumped,but occasionally would drain it,s oil tank into the sump,usually overnight.
Upon startup it would then pour oil out of the breather pipe and produce enough smoke to hide a battalion of soldiers.
Never could never find a solution to the problem!

Yep, in Norton-land they call that "wet sumping." (However, your Triumph people like to reserve that term for when the scavenge pump fails. Norton and Triumph people like to argue about this.) If you take everything apart, lap the oil pump and get everything right etc, you can eliminate the drainback, at least for awhile. I have one Norton twin that does it and another that does not.

But there is no perfect way to fix it once and for all except to install a manual shut valve, and you can see the problem with that. Long ago I knew an old bike mechanic, Native American, who made a device for his customers that was a combination shut valve and ignition cutout. Beautiful little thing. Brass of course.

Between marvelous features like this, the Harley total-loss primary case, etc, you can see how the Japanese were able to walk in and take over the industry overnight. Their ads showed people riding motorcycles wearing white slacks.

[McGuire]

Originally posted by Bill Sherwood



Well more like hardly any in fact.
Only Harley (and hence Buell) use it these days that I know of.

More than a few actually. A common practice in four-stroke thumpers (Enduro, Supermoto) is dry sump with oil-in-frame. Yamaha, Honda, KTM etc.

[J. Edlund]

Some military and marine diesels also use dry sump lubrication.

[NRoshier]

I think I may have a better understand of some of the production systems now. The LS7 is not dry sumped in a traditional motorsport sense. It does have a scavenge and pressure system, but not with a belt drive (the problematic part?) instead it seems an adaptation of the original pump. See http://www.superchev...mbly/index.html
Looking at all of the after market kits, I wondered why there is no use of multi-rib belts instead of tooth belts. Local supercharger companies have all moved to multi-rib, so drive is not really a problem.

[Bill Sherwood]

Originally posted by McGuire


More than a few actually. A common practice in four-stroke thumpers (Enduro, Supermoto) is dry sump with oil-in-frame. Yamaha, Honda, KTM etc.

Ta, I didn't know that.

[McGuire]

Originally posted by NRoshier
I think I may have a better understand of some of the production systems now. The LS7 is not dry sumped in a traditional motorsport sense. It does have a scavenge and pressure system, but not with a belt drive (the problematic part?) instead it seems an adaptation of the original pump. See http://www.superchev...mbly/index.html

For the obvious reasons you probably won't find a serious production vehicle with a belt-driven oil pump. However, no reason the pump must be driven by a belt to be a proper dry sump system. If it scavenges oil from the crankcase and stores it somewhere other than the sump, it qualifies as a dry sump in my book. That is the object after all, to obtain a dry sump -- so the oil supply is not subject to windage and g loading.

[J. Edlund]

Originally posted by NRoshier
I think I may have a better understand of some of the production systems now. The LS7 is not dry sumped in a traditional motorsport sense. It does have a scavenge and pressure system, but not with a belt drive (the problematic part?) instead it seems an adaptation of the original pump. See http://www.superchev...mbly/index.html
Looking at all of the after market kits, I wondered why there is no use of multi-rib belts instead of tooth belts. Local supercharger companies have all moved to multi-rib, so drive is not really a problem.

Belt driven systems are generally only used with production based racing engines. With engines purely designed for racing the dry sump pump tends to be gear or in some cases chain driven. Thier scavenge sections also tend to have a greater capacity so that a below atmospheric pressure can be reached in the crankcase.

As for the belt, you really don't want the belt that powers the oil pump to slip.

[Bill Sherwood]

Originally posted by J. Edlund
As for the belt, you really don't want the belt that powers the oil pump to slip.

Most are toothed belts, such as on one of my racing cars ->




For one of the engines I'm building, I was looking at running a gear-drive off the front of the crank pulley but decided not to out-smart myself and just stick to a conventional belt & pulley instead.

[NRoshier]

for my project car I was interested in keeping the original pump for pressure purposes and then add another external pump for scavenge, in effect making a dry sump system...hence my interest.

[robroy]

Sounds like an Accusump could be the answer:
http://www.accusump.com/

A couple more questions:
Are windage trays still useful on atmospheric dry sump systems?

I've fitted an external belt driven oil pump but I'm still losing oil pressure under hard continuous cornering. Is this most likely to be down to my oil tank design/positioning?

[NRoshier]

I am familiar with the accusump systems, but there is a secondary gain with the dry sump and sump modification that I am keen to follow up in the longer term...it would allow my 200kg engine to go 50mm lower in the car and I could get some better structure under the engine too...in the longer term.

[Scotracer]

Originally posted by McGuire


More than a few actually. A common practice in four-stroke thumpers (Enduro, Supermoto) is dry sump with oil-in-frame. Yamaha, Honda, KTM etc.

Yep. My Suzuki DR thumper is a dry-sump with the oil in the frame. Good design.

[jeremy durward]

Originally posted by NRoshier
for my project car I was interested in keeping the original pump for pressure purposes and then add another external pump for scavenge, in effect making a dry sump system...hence my interest.

a mate of mine did this in a corolla hillclimb car with a 4AGTE . it worked really well, he used a holden 202 oil pump for the scavenge pump, then back from the tank to the orig pickup.

[NRoshier]

yes, pretty much what I was thinking of. Allows good supply of oil not as subject to the usual windage issues...not that I will be needing to worry about it just yet!
So would go full circuit: scavenge pump - tank - oil cooler - pressure pump - filter - engine - scavenge pump

[jeremy durward]

are you planning on using an aftermaket type pump or modifying something to fit?

[NRoshier]

I had looked at the high volume Empi VW pumps etc...but the moroso external pump is also available. I'm open to options but have plenty of time to look around.

[mariner]

If you want a good treatise on dry sump design may I recommend the "Chevrolet power book". There is a whole chapter on dry sump design.This book is written in very non-fancy english but I suspect it has the distillation of a LOT of experience in it.

Mine is a second edition from 1994 with no ISBN but I presume it has been upadted and I would think it is available from Summit or similar who can ship w/wide.

[McGuire]

Originally posted by mariner
If you want a good treatise on dry sump design may I recommend the "Chevrolet power book". There is a whole chapter on dry sump design.This book is written in very non-fancy english but I suspect it has the distillation of a LOT of experience in it.

You don't say.

[NRoshier]

your work McGuire?
I'll have a look online for it.

[Fat Boy]

Originally posted by mariner
...This book is written in very non-fancy english...

Well, if it walks like a duck....

[mariner]

I was actully indulging in English understatement here!

The Chevy Power Books have been my bible in working out how to build a strong big block, they are packed with data and knowledge.

Also the early editions had a section at the back on handling and aerodynamics complete with dynamic pressure calculations. I would love to know who wrote that bit.

[crono33]

the rotax 912 that powers my little airplane uses a dry sump system. there is no scavenging pump.
the oil accumulates in the bottom of the crankcase and is pumped back into the tank by the pressure generating in the crankcase.

[Greg Locock]

That's an interesting idea. We can't do it on production cars because of HC emissions, and it is too much of a drag on fast revving F1 engines.

But I do like oil pumps that have no moving parts.

[GBarclay]

NRoshier

l have use Gary at Armstrong Race Engineering in California for dry sump stuff for years. He developed and worked with us on the Buick Indycar motors, and lately I have used him for LS6 Vette motor dry sump stuff for rock crawlers

I believe he is the go to guy for Pratt and Miller's Vette's too.

Dont know about other bikes but the Hayabusa in my sports racer was originally wet sump, that has since been converted. Transmission and motor share lubricants.

HTH

[cheapracer]

Well I've spent a lot of years in bike shops and Brit bikes onwards, not many of them are dry sumped.

Big thumpers (400cc up singles) need to be because of engine height problems, not lube problems - also why Harley run dry sump. What looked like the sidecover of a Honda 7504 was in fact the oil tank under the seat and they were dry sumped but I don't know why

But the majority of daily, touring and sportsbike bikes are combined engine/box wet sumped because bike's lean into corners negating the g force slosh pickup problem. Some car racers who run bike motors have to either dry sump or run an Accusump http://www.accusump.com/ type standby oil system pressuriser. One of my mates came off the bridge into the right hander twice at Oran Park in a sports racer (big G's there) and popped 2 Kawasaki Z10 motors before installing an Accusump and has never had a problem since.

[cheapracer]

Originally posted by NRoshier
I am familiar with the accusump systems, but there is a secondary gain with the dry sump and sump modification that I am keen to follow up in the longer term...it would allow my 200kg engine to go 50mm lower in the car and I could get some better structure under the engine too...in the longer term.

Sorry Roroy, didn't see your accusump post.

NR, some racers like to keep the sump as far away from the crank as practicle too to keep windage under control, dry sumped or not - something to consider.

I like the American practice of oversucking the sump even using exhaust evacs as well to keep windage well under control gaining HP by keeping the crank "oil rope" as small as possible. - matching the crankcase's low pressure to the cranks low pressure areas behind the rotating webs. Again I refer to Grumpy or Smokey for this type of stuff and why they get massive HP from 2 valves and pushrods.

[NRoshier]

GBarclay thanks for the information.
Cheapracer the sump will remain as it is, but even if modified it would result in the removal of the most of the 'well' section in the new casting. I'm sure the exhaust evacs would not be compliant with emissions, which I have to comply to as part of the ADR requirements.
I have had some information regarding the problematic situation with dry sumped road cars - when the oil is cold it is thick (no surprise) and when starting the engine the dry-sump pump pressure section is trying to push this thickened oil all around the engine which provides a significant load on the belt. The scavenge sections will also encounter a head of oil on startup, but they do not have to force it around a complicated circuit and pressurise the circuit, but they do have an initial 'high' (relative to normal warm operation) load period.
What I proposed with the scavenge pump will be less of an issue.

[cheapracer]

Originally posted by Bill Sherwood


Most are toothed belts, such as on one of my racing cars ->




For one of the engines I'm building, I was looking at running a gear-drive off the front of the crank pulley but decided not to out-smart myself and just stick to a conventional belt & pulley instead.

Can't run say a 420 chain and alloy sprockets Bill?

[NRoshier]

multi-V belt?

[cheapracer]

Originally posted by NRoshier
multi-V belt?

Seriously I wouldn't consider anything other than a positive drive system, 'O' ring chain is low power loss, doesn't need lubing, alloy sprockets made to order are common enough (not that a 420 steel sprocket weighs much) and very narrow if space is a consideration.

[NRoshier]

true enough on the space and power loss. I am keen to explore a multi-v belt for my purposes as I already have a spare pulley on the crank that was used for the power steering pump.

[Ray Bell]

Another car that had a dry sump was the Honda series of the late sixties... the Coupe 7 and Coupe 9...

1300cc (and 1500cc?) air cooled front wheel drive SOHC, probably used it for additional oil cooling.

[bobqzzi]

Originally posted by NRoshier
true enough on the space and power loss. I am keen to explore a multi-v belt for my purposes as I already have a spare pulley on the crank that was used for the power steering pump.

Given that most drysump pumps turn at 1/2 engine speed, I think you'll find it hard to size v-belt pulleys correctly

[NRoshier]

There is one spare on the crank and I can make one to suit the needs...much easier to make than a toothed belt.