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Opinions on reducing sump depth
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rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Fri Jan 01, 2016 9:11 am    Post subject: Opinions on reducing sump depth Reply with quote

I've got here a sump on a 1980's injected engine. This model (Suzuki G16) engine is commonly used in kit cars and a common modification is to fit a more shallow sump from the smaller G13 engine.



I'm trying to keep centre of gravity low. The sump has a shallow end and a deep end. I only need to make the shallow end more shallow so I can bring my diff up. What are people's opinion on modifying the sump on that side so it only clears the crankshaft by 10mm?

It looks like the shallow side only serves to collect oil, which then flows to the deeper end where it can cool and be stored.

But there is what I assume is a baffle in the shallow end. Basically it has two levels in there.
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peter scott



Joined: 18 Dec 2007
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Location: Edinburgh

PostPosted: Fri Jan 01, 2016 10:15 am    Post subject: Reply with quote

I think that if you have made some allowance for crankshaft whip in calculating the clearance of big end bolt heads then there shouldn't be a problem other than perhaps a small increase in drag from the rods dipping into the oil.

Peter
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rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Fri Jan 01, 2016 11:21 am    Post subject: Reply with quote

I should add:

10mm is my ideal clearance. But can be increased.
This isn't some rare engine, it's still widely available, and it will do low mileage. So if the modification increases wear it's not the end of the world.

Whats the purpose of the second level that's in the sump? I think it's called a baffle.
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Farmer John



Joined: 18 Feb 2010
Posts: 170
Location: Manawatu NZ

PostPosted: Fri Jan 01, 2016 8:32 pm    Post subject: Suzuki sump Reply with quote

Hi. Of course you can, go for your life! The only limiting factor is that the oil needs to get back as quickly as possible to the deep part, which is deep to contain the oil for the oil pump. Best not interfere with the oil volume or level, the Suziki engineers have figured all that out.
Incidentally, one of the first things a V8 tuner will do is fit a full sheet-metal baffle which is curved to fit closely under the crank with slots to let the oil through, to reduce air drag on the crank. They run so closely that when fitted new sometimes the crank will hit the plate and make horrible noises causing the fettlers and fiddlers to insist that your bearings are shot. Just hammer the baffle where it touches.
Just by the way, the big risk in those circumstances is that a spark from the grinding will light up the oil mist in the crankcase and explode, blowing your oil filler cap and dipstick, and some seals as well.
Contact me if you would like further discussion.

John
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rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Fri Jan 01, 2016 8:41 pm    Post subject: Reply with quote

Thanks John.

So that shallow part of the sump just moves the oil along to the deeper part?

So you're saying I can really tighten things up. The baffle can be close as mechanically possible and then below the baffle a gradient to take the oil to the deeper part. That's great and that solves some big obstacles for me.

Thank you all!
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Phil - Nottingham



Joined: 01 Jan 2008
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Location: Nottingham

PostPosted: Fri Jan 01, 2016 10:05 pm    Post subject: Reply with quote

The deep part of the sump is there for 2 principle reasons. 1st is to act as a collection point for the the pump pickup and 2nd to provide a suitable reserve of oil. Some cooling effect is also provided.

A dry sump set up is also another option to allow minimum sump with a scavenge in the lowest part which ensures NO loss of pressure on braking cornering as oil sloshes around on cornering/braking.

A separate reserve tank for the oil is also required and perhaps an oil cooler
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Last edited by Phil - Nottingham on Sat Jan 02, 2016 9:34 am; edited 1 time in total
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ka



Joined: 03 Dec 2007
Posts: 600
Location: Orkney.

PostPosted: Sat Jan 02, 2016 9:08 am    Post subject: Reply with quote

A shallow sump is no problem, BUt, do not allow the crank throw to enter the oil level, so do not alter the oil level.
There are two ways to give less drag to the crank, a fitted baffle is one, but the best way is a polished crank, it will spin through the air/oil mist/splashed oil more easily.
To maintain oil capacity you can widen the sump; this will have problems that can be overcome, but the best way is to use an oil cooler with a thermostatic by-pass. The reduction in oil quantity is not an issue with oil quality as modern oils are far superior to older mineral oils, but, the reduced volume will heat up quicker, and will not loose its' heat as quickly as there is less of it.
If you really want to go for it, use as suggested a dry sump, solves most of the problems, but comes with an additional weight penalty.
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rcx822



Joined: 31 Dec 2010
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PostPosted: Sat Jan 02, 2016 10:51 am    Post subject: Reply with quote

Hi Ka.

It's only the shallow end that I want to modify, so the oil level and capacity should stay the same as the oil sits in the deeper end.

That deeper side is behind the diff so unless it's bigger than the diff it's not causing any problem.
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Peter_L



Joined: 10 Apr 2008
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Location: New Brunswick. Canada.

PostPosted: Sat Jan 02, 2016 3:06 pm    Post subject: Reply with quote

Care that you don't create an isolated pool of oil at the far end of the shallow section.
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rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Sat Jan 02, 2016 3:10 pm    Post subject: Reply with quote

peterwpg wrote:
Care that you don't create an isolated pool of oil at the far end of the shallow section.


I will take care. But tell me what would happen if there was a pool?

I'm going to design the sump on CAD and have it fabricated. My fabricator is very accurate thankfully. I used to make this kind of stuff myself but I now find it better to use a decent but affordable fabricator.
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Peter_L



Joined: 10 Apr 2008
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Location: New Brunswick. Canada.

PostPosted: Sat Jan 02, 2016 3:21 pm    Post subject: Reply with quote

rcx822 wrote:
peterwpg wrote:
Care that you don't create an isolated pool of oil at the far end of the shallow section.


I will take care. But tell me what would happen if there was a pool?

I'm going to design the sump on CAD and have it fabricated. My fabricator is very accurate thankfully. I used to make this kind of stuff myself but I now find it better to use a decent but affordable fabricator.


For myself, I wouldn't want to create a pool of oil that was out of the circulation cycle. Could it perhaps get very hot, to the point of evaporation, or as it fills to overflowing, (eventually), there is above norm, hot oil being returned to the deep part. It is an area that would never drain and sludge accumulates.

Not very scientific but the idea just doesn't rest easy with me.
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rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Sat Jan 02, 2016 3:30 pm    Post subject: Reply with quote

peterwpg wrote:

For myself, I wouldn't want to create a pool of oil that was out of the circulation cycle. Could it perhaps get very hot, to the point of evaporation, or as it fills to overflowing, (eventually), there is above norm, hot oil being returned to the deep part. It is an area that would never drain and sludge accumulates.


I understand. Careful design and fabrication will take care of it.
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