Under Piston Oil Spray Jets

[Woznaldo]

The C1J does NOT have under piston oil spray jets. The newer Renault (and most other manufacturers) engines do have these and they appear to help in several different ways. As the title suggests a Jet of pressurised oil is directed to the underside of each piston with the primary aim being cooling the piston the gets very hot during the combustion process.

The Oil Spray also assists with providing additional oil film to the cylinder bores.

The question though, is would it be worth it on the C1J?

Earlier Cosworth YB didn't have them, but they fitted them to all their rally engines, so there must be something in it? Burton Power (to name one supplier) sell a kit to retro fit to the YB Blocks that don't have them fitted.

Now there are several ways to achieve the effect. The most common is to drill into a block oil way and tap the oil off with metered tube. This is what Burton Power sell. Pic below:



Burton Power Kit



Another method is to put small holes into the Con Rod that direct oil from the Big End Bearings to then fire up towards the Pistons. I'd say this is the least common route.



The next method is the one that intrigues me. A hole is drilled from the Main Journal at an angle to then come out of the Block Casting in such a way to then spray directly to the underside of the Piston. Here's a video that shows what I mean.

https://www.youtube.com/watch?v=cqfijPy2Gn0

This final method is probably the way I'd go for the C1J if I was going to do it. What are peoples thoughts on the subject?

[James5]

BBPT done this to some C1j's a few years back as an optional extra on there top package's, I haven't actually seen one so would be interesting to see how they done it

[Woznaldo]

BBPT done this to some C1j's a few years back as an optional extra on there top package's, I haven't actually seen one so would be interesting to see how they done it

Good info James. I bet that Tony Hart has also done it to his Hillclimb engine.

If anyone has got one of these BBPT engines and has it stripped or pictures of when it was stripped, please post them up so we can take a look!

[Alastair]

BBPT was a good mod, they drilled into the block as in pic 1

[Alastair]

There are pics in their old catalogue, my catalogues went with the rally car I'm afraid in the folders...

To be honest if you are racing you'll rebuild your engine regularly anyway. Long term benefits on a fast road car... mmmmm... id put my money into total seal piston rings instead...!

[Woznaldo]

I didn't find any pics, but it's still listed in the Engine Dynamics top level engine spec:

http://www.engine-dynamics.com/Engin...uildLevel3.asp

[w35ty]

Good to have really, im sure when i stripped my mates evo engine he had similar to the first pic if i remember right

Surely not hard to do if bought the kit?

[Matty]

Lot of us A series boys fit them. Either use the zetec or bmw jets. With it on highere boost engine to keep the crowns cool.

[Matt_S]

Nissan fitted them to their turbo models, but not the NA models

The CA18DET had them but the CA18DE didn't.

The std pistons run quite a low skirt, so they had a cut out to clear the squirter.

http://www.z1motorsports.com/240sx/p...vd7&imageNum=2

[michael tierney]

the origional jets were put there to cool the piston because the combustion chamber was in the piston(head was flat).......they're no real benefit on a flat piston like the c1j....it would be alot of work for??

[turbo ted]

Renault F7p run flat top pistons and they have under spray jets as standard,and drilling 4 holes to fit the jets is hardly a big job

[Woznaldo]

Lot of us A series boys fit them. Either use the zetec or bmw jets. With it on highere boost engine to keep the crowns cool.

I'm worried about space. The A Series only has three main bearings, which means there's a bit more internal space. That said, have you got any pictures of how it's done on an A Series?

[Woznaldo]

Here's a short article on fitting Oil Spray Jets to an A Series Engine. Obviously the princible is still the same, but the obvious difference is that on the C1J the Liners protrude below the limit of the Block casting, therefore presenting a 'lip'. So the Jet would need to get over this hurdle. Not the greatest challenge, but not as straight forward as the A Series.

http://www.turbo-mini.com/44648/23109.html

[Matty]

These are BMW ones fitted. Also been done on a small bore engine too. it would be possible to make some tube nuts to extend them below the liner. So you basically have a tube with a male thread on one end and female on the other, with an oil feed hole through the centre.

[Woznaldo]

That's great info Matty, what BMW Engine are they from? BMW Mini?

[Matty]

I can't remember now, but I'll ask my mate as he works for bmw and just bought a set.

[youngscottie]

I thought about this years ago
My intention was to rig up something like I had in my by cossie
It looked like a length of brake pipe coming of the pump donning along the block with jets in
In the end I decided not to as I doubt the gt oil pump is up it the job

[Woznaldo]

The pump capability is a concern, but as mentioned in the turbo-mini article, as long as the jet orifice opening isn't too large, it should be fine.

The Engine-Dynamics top engine doesn't appear to have a better/upgraded oil pump, just refurbished?

[Matty]

The bmw ones are set to only up at 40psi or there abouts, then shut back off below that.

[butch]

I am a numpty when it comes to technical matters but I have it on mine, Engine Dynamics having done my rebuild at the start of last season. My understanding is that their approach is to achieve under piston spray as a result of some clever machining of the crank rather than this system of jets. If I'm wrong please forgive my ignorance but Andy junior at Engine Dynamics was tremendously helpful during my rebuild process, he's the man to talk to ( as well as Tony Hart!)

[Woznaldo]

The bmw ones are set to only up at 40psi or there abouts, then shut back off below that.

They must have a check valve or even a metered orifice to achieve that? It would be easy enough to test?

[Woznaldo]

I am a numpty when it comes to technical matters but I have it on mine, Engine Dynamics having done my rebuild at the start of last season. My understanding is that their approach is to achieve under piston spray as a result of some clever machining of the crank rather than this system of jets. If I'm wrong please forgive my ignorance but Andy junior at Engine Dynamics was tremendously helpful during my rebuild process, he's the man to talk to ( as well as Tony Hart!)

It's probably like the 3rd picture in my first post? If I was going down that route, I would drill the jets so that they're firing straight up at the Piston?...

I have email Engine Dynamics to ask them how they achieve their under piston spray, but have yet to get a reply?

[Matty]

Yep got check valves inside them. The Zetec ones do to from memory. They were about £40-£50 for a set of 4 a few years back now.

I would hazard a guess and say that the drillings are positioned to be pointing at the piston when it 90 degrees BTDC/ATDC. The thing that concerns me about drilling the rods, would be weakening them, and you would also be relieving some of the oil pressure on the top shell which could cause premature bearing failure.

[Woznaldo]

Yep got check valves inside them. The Zetec ones do to from memory. They were about £40-£50 for a set of 4 a few years back now.

I would hazard a guess and say that the drillings are positioned to be pointing at the piston when it 90 degrees BTDC/ATDC. The thing that concerns me about drilling the rods, would be weakening them, and you would also be relieving some of the oil pressure on the top shell which could cause premature bearing failure.

Matty, I think there could definitely be some integrity issues with drilling into the Rods and any gains from the extra cooling could be undermined by the loss of strength in the Rod?

I'm not sure if there would be a huge loss of film on the Big End Shells as the Big End Journal is spinning 360 inside. Bottom line is it's an unknown and to my mind not the preferred method. If Engine Dynamics could explain their method (assuming it's drilling the Rods) and back it up with data/history etc, I might be swayed a bit more?

[Matty]

My line of thinking is that the oil will be spraying out of the rods at pressure and that pressure has got to come from somewhere. If you use oil jets drilled into the mains feed, then the pressure 'lost' in the system is spread accross the lubrication system as a whole and not localised on the big end shells, which are the last ones that you want to starve of oil. Having a film of oil is different to having a pressurised film of oil.

I'll get that part number for the jets over the weekend.

[Woznaldo]

Part of the reason for starting this thread is because I currently have Block stripped down and I'll be sending it to a machine shop for cleaning. This place is a machine shop and will have the facility to do the job properly.

[Woznaldo]

These are the Zetec Oil Spray Jets:



I'd like to know at what pressure these close?

These are Honda offerings:

[Woznaldo]

Ok, so I took a few pics friends from below the block to look at potential positions for the Spray Jets. Now we need to tap into an existing oil supply source to make this work and I'm not sure if the Cam Bearing Journals line up with the spaces between the Main Journal walls. I guess this is why some tap into the Main and Big End Journals themselves as they're a know source?









If anyone does have a block with the ED/BBPT Oil Spray mods and has pictures or their Block is off the car, I'd love to see some pics.

[Matty]

I'm sure the zetec ones open at 40psi.