Race Engine Forum UK

Guy

I have been following your article on the forum on converting the 131TC sump and am applying the same principles to the sump on my FIRE engine.

The reasons for the conversion are two fold:

The first is that I plan to do some track days this year and want to make sure that the small fortune I have just spent re-boring, balancing and re-building my engine is not wasted by oil surge/starvation in the standard – designed for transverse application – un-baffled sump.

The second is that as the engine is mounted in the rear of the car, the deepest part of the sump is the furthest back (see pic) and well away from the axle which makes it very venerable to speed humps and ramps.

So in short I am trying to gain some control over the oil flow in the sump and in the process hope to gain some extra ground clearance .

I have cut up an old sump (have yet to set everything up at the correct angle) and am mocking-up the size and shape and depth of the wings and windage tray in cardboard before I cut any metal (4mm base 1.5 for the rest) but I have a I have a couple of questions that if answered will help me to progress the project. The existing alloy oil pick-up extends into the center of the sump, if I shorten it, it will result in the head of the pick-up being positioned in the far corner of the sump rather than central, is this OK or, do you think it would be better to fabricate a new one in steel (find a steel gauzed head from another car) with a swan necked pipe that brings the head closer to the center again. I have tried to do a quick sketch over a photo to illustrate.

In the pictures of your 131TC sump the windage tray has sides that extend down almost to the base, what sort of gap should be left between the bottom of the sides and the base of the sump? Do you weld these to the base at any point or just to the top plate of the tray? I have only seen these without sides before.

Should the sump be fitted with a breather (if so where is the best place and should it go into the catch tank or have its own breather filter), there was an article in Retro Cars a few years ago on tuning the FIRE engine that suggested that it helps to reduce pressure and limit the amount of oil being blown past the rings in a high revving engine, I don't know the specialist that gave the advice so thought I would solicit your opinion.

I know you have recently done a FIRE sump for Huw for his 750mc racer, are there any peculiarities you came across when working on this one?

Any help would be much appreciated

I hope you are keeping well

Nigel

Photos sent by email.

GC

Guy

Thanks so much for sending over the pics of the fire sump it is much appreciated.

Its taken ages to get this far but the sump is almost ready for final welding, just need to sand blast then cut out the piece that runs across the center and replace with the new bit then add 3mm base plate. It is the second attempt, the first got as far as finished components, fettled for a perfect fit but a change of plans with the engine meant that we have gone from a 1108 block to a 1242 16 valve one which is 10mm wider where the sump mounts so the first version was junked.

We had planned to use the pistons from the latest 1368 version of the FIRE engine in the 1108 block to give a 72 bore x 72mm stroke but when the pistons arrived it became evident that we would have take too much off the block and head to get the right CR so we had to switch to the longer stroke 1242.

I have one question, in the pictures you sent over there is no top baffle a the front of the sump, do you think it is worth putting one here as well? In one of the pics I can see a vertical piece that had been added, does this act as a baffle?

Thanks again for your help, I will post up some images for the finished item once its completed

Nigel

Well done, a very nicely presented article!

If you mean should you put a top baffle where marked yellow, yes, otherwise the oil will fly everywhere under braking, but make sure it's slotted to let the oil drain down. In the same vein - don't make top baffle at the cambelt end too close fitting, maybe you need a few mm relief around the sides. Take a look at the attached. The slots should catch oil in direction of crank rotation, as I'm sure you know.

Take great care to get all the grit out after blasting, tap the sump several times with a small dead-blow mallet to release the grit that gets trapped in the welded joint regions.

G

Guy

I think I'm almost there with the sump, it just needs the top baffle welding in, I did however wake up in a hot sweat at 4.00am this morning thinking hat I had put the slots in the wrong way round, can you confirm that the pressed part of the slot should be before the flat creating a wide open hole for the oil to be flung into as the crank rotates in a clockwise direction.

I'm sure I have done it right, see below, I am getting it welded this afternoon and will post some more build pics when its painted

No worries there, what you've done is correct; it doesn't matter whether which side of the windage tray you press the slots provided the entry section is facing the right way, which it is.


As my diagram shows the direction of rotation of the crank is clockwise viewed from the crank nose (front pulley end) and thus the oil will be flung towards the slot entry sections and under the windage tray.

GC

Thanks Guy,

Good to know I'm on the right track

Nigel

Its finished! thanks for the help Guy,

I hope I have done your directions justice.

Nigel
Shortened oil pick-up
top baffle
Home made tool for making the cheese grater type holes
Finished sump on engine

Guy,
As often happens with these kind of projects, an engine rebuild turned into a full bare metal restoration of the whole car with custom made hubs, wheels, brakes, Cooling system etc The net result of this is that some four years later I've just started the engine that the winged sump was fitted to for the first time.

Unfortunately I have low oil pressure - about 8 psi at tick-over when up to temperature. All bearings in the engine are new so I thought the best place to start was changing the oil pump. I've put a new one on but it's only made a marginal difference. When I started making the sump it was for the 1108 version of the engine but we ended up changing to a 1242 block. I used the shortened pickup pipe from the 1108 on the 1242 pump.

Looking at the two pickup pipes together now the 1108 one is a narrower bore by around 3 mm ( the 1242 one is 17mm at the top but does reduce a little on two sides), do you think that the narrower bore would make a difference to the oil pressure? I would think that, if it did make a difference it wold be at high revs rather than at tick-over but I would love to see what you think.

The factory manual for the Seicento gives oil pressures of more than 0.7 bar at idle, 4 bar + or - 0.4 at 4,000rpm. Take Guy's advice, rather than mine, but few guages are super accurate. If the figure at 4,000 rpm is within limits, I'd be inclined to discount the figure at idle.

I ran a 1108 turbo Cinq which gave similar readings (which are scary to those bought up on certain English engines) and put out 115 bhp. Although it died a horrible death that was due to fuelling induced detonation, not to low oil pressures.

please reload your photos using the site hosting service not

http://www.retro500.com

and I shall, in return, guide you..

G

Pictures now uploaded onto the hosting service with the exception of the two in the first post which seem to have gone on the missing list, will have a look at my back-up disks.

Nice job on the pics, thanks, they are important!

Re:

"Unfortunately I have low oil pressure - about 8 psi at tick-over when up to temperature. All bearings in the engine are new so I thought the best place to start was changing the oil pump. I've put a new one on but it's only made a marginal difference. When I started making the sump it was for the 1108 version of the engine but we ended up changing to a 1242 block. I used the shortened pickup pipe from the 1108 on the 1242 pump.

Looking at the two pickup pipes together now the 1108 one is a narrower bore by around 3 mm ( the 1242 one is 17mm at the top but does reduce a little on two sides), do you think that the narrower bore would make a difference to the oil pressure? I would think that, if it did make a difference it wold be at high revs rather than at tick-over but I would love to see what you think..


It's not an airlock in the oil presssure gauge is it? (if capillary type).. I get that on my rig sometimes. Oil pressure drops as the oil heats up what is the oil temp hot? You don't want it going over 85 degC or the pressure will really drop due to the high bleed-down rate.

Ignore idle for now, what is the oil pressure at 3000-4000 revs (off load will do, but I need to know the oil temp at which the pressure was measured, readings with cold oil mean very little btw..) you need about 10psi per 1000rpm up to a max of say 55-60psi at 5000 and over - though some engines have more.

If you have oil cooler and external oil lines etc they DO rob oil pressure. It might be an idea to examine the relief valve setting on the oil pump and maybe shim it up.

The reduction in pickup would be significant if the reduction is 3mm on a 17mm diameter on the pickup that would be something I would be bound to correct, it would be a reduction of area some 30% if my math is right..if the pump gears are bigger it could cause cavitation. I stress 'could'. Open it up with a burr is my advice.

New bearings - ok. Was the crank reground? Did it turn freely by hand when the caps were torqued up? if you cannot pin the loss of pressure on anything else drain the oil (hot) and inspect it for bearing debris.

I have dwelt extensively on oil pressure in my 2010 book - if you do not have it you might care to get it.

Hope that helps for now,

G

Not looking great, 22-23 psi at 4130rpm

Bled gauge so this should be reading OK

Bearings were new but I'm not sure if the crank was reground, the guy who built the engine for me has moved out of the country and I don't have any contact info!
Will drain the oil out over the weekend and report back. I'm going to modify the pick up pipe, is it worth having a look the big ends while the sump is off?

Will phone about your book on Friday

I'd certainly check the bearings.

Now's not the time, but would love to see photos of the car.