Lotus Elan

Problem with Crankcase Ventillation

PostPost by: prezoom » Tue May 08, 2018 3:43 pm

I have an engine with a Weber intake welded to a Stromberg head. Have no Idea where it came from, or who made the modification. Looks nothing like I have ever seen before.
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PostPost by: 2cams70 » Tue May 08, 2018 11:44 pm

You don't really need a catch tank either by the way if you are using the kent separator because the separator prevents most if not all of the oil from being vented together with the blowby fumes.
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PostPost by: Chancer » Wed May 09, 2018 9:04 am

Put a catch tank on the end and you will see that is far from the case, I had a brass cock on the bottom of mine on my X/flow westfield to recover the very clean oil such was its quantity, it definitely gets exponentially worse with tuning and higher revs, perhaps a standard unmodified engine would be minimal.
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PostPost by: Certified Lotus » Wed May 09, 2018 9:49 am

oldelanman wrote:The Kent breather you removed is probably baffled inside to catch the oil thrown up from the jackshaft fuel pump lobe, does the Burton elbow have a baffle inside ? Burton also sell a blanking plate with a deflector attached to prevent similar problems occurring with the standard breather system if the fuel pump is removed to fit an electric pump.
http://www.burtonpower.com/fuel-pump-bl ... fp281.html
The attachment FP281_Blanking_Plate.jpg is no longer available


My engine builder made one of these blanking plates with a deflector (I have an electric fuel pump) as the TC engine in my S1 has a metal vent tube that runs from the engine along side the transmission to the street. Nothing but a rubber elbow from the engine to the tube and two attachment points. No baffled box. He said without the deflector I would have oil pouring out the vent tube all the time. After three years of driving I can tell you there is very little oil coming out of that tube.

My track Exige S had an elaborate baffled vent system that went to a catch can. Without the baffles the catch can would fill with oil after every track session.
59d75082-0047-401c-b0c9-9e32cd98f9b6.jpeg and

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Last edited by Certified Lotus on Wed May 09, 2018 7:37 pm, edited 1 time in total.
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PostPost by: 2cams70 » Wed May 09, 2018 12:51 pm

I must admit I find the whole idea of catch tanks a bit strange. Bit of a boy racer add on in my opinion. If you have a properly designed separator and ventilation system you shouldn't need one, any oil separated out is returned to the crankcase.
No road car ex-factory ever has a catch tank no matter how exotic or high performance!
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PostPost by: nmauduit » Wed May 09, 2018 1:27 pm

2cams70 wrote:I must admit I find the whole idea of catch tanks a bit strange. Bit of a boy racer add on in my opinion. If you have a properly designed separator and ventilation system you shouldn't need one, any oil separated out is returned to the crankcase.
No road car ex-factory ever has a catch tank no matter how exotic or high performance!


it is not that obvious to me to get a "properly designed separator and ventilation system", esp. considering the possibility of an engine failure that increases blow back or otherwise blows with the effect of pushing more vapours out (head gasket leak etc) - and since these days any oil on the tarmac results in fees to pay for the cleaning, I will install a catch tank to be on the safe side. It also would help to track what's going on inside by checking regularly what is added to the tank.

I still will give a try at making up a separator hoping to minimize the amount ending up in the tank, and I'm planning to do that with an aluminium tube filled with steel wool and hopefully long and cool enough to condensate most of the vapors going up. The separator tube will be installed going up so that the condensates should be able to make it back to the crank during throttle off moments, and will have a brass mesh at the bottom to keep eventual small parts of the steel wool to fall in the crank (I may add a magnet to be on the safe side...).

not done yet, but reasonably high on the todo list to be tried this year :)
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PostPost by: 2cams70 » Wed May 09, 2018 1:42 pm

Admittedly all modern road cars have closed crankcase ventilation systems. It would be interesting to know what system F1 engines use.
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PostPost by: promotor » Wed May 09, 2018 6:49 pm

2cams70 wrote:Admittedly all modern road cars have closed crankcase ventilation systems. It would be interesting to know what system F1 engines use.


They vent to atmosphere as of 2018.
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PostPost by: vstibbard » Fri May 11, 2018 8:56 am

Hi

The Burtons type 90deg breather gets oil thrown at it by the shaft that drives the distributor and oil pump, this then flows down the pipe, which is why the Ford type breather box has inlet and outlet offset and a plate running horizontally through it to stop oil travelling up.

You need a deflector to stop the oil being thrown up if you wish to use the Burton breather outlet. Ordinarily they are used with fuel pump blanking plate that has on a plate that deflects the oil.

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PostPost by: The Veg » Sat May 12, 2018 12:07 pm

2cams70 wrote:If you have a properly designed separator and ventilation system you shouldn't need one, any oil separated out is returned to the crankcase.


'If' and 'properly' being the key words here.
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