13b N/a ?....

[oldone]

Old school bro............yipeeeeeeeeeeeee.....:cheers :InLove

[yoeddynz]

So someone\'s done the maths to work out an equivalent to what the OMP puts out as far as premixing...?
I just wouldnt want to get it wrong.. although I could always just add more to be safe...
I do like the idea of being covered in case the OMP failed- and the idea of not having it and its little lines spoiling the veiw of such a nice lump..

As far as the manifold goes..its a bit different to mine- only having one cast in point for the OMP lines or vacuum. Plus the bolts look wonky but that might just be me?
But its cheap eh..

[Dominic]

So someone\'s done the maths to work out an equivalent to what the OMP puts out as far as premixing...?
I just wouldnt want to get it wrong.. although I could always just add more to be safe...
I do like the idea of being covered in case the OMP failed- and the idea of not having it and its little lines spoiling the veiw of such a nice lump..

As far as the manifold goes..its a bit different to mine- only having one cast in point for the OMP lines or vacuum. Plus the bolts look wonky but that might just be me?
But its cheap eh..

If you had the time, some steel/ali tubing and a welder, reckon you could make a much better inlet manifold than any of the cast jobs. Just gotta make sure you get the tube diameters right, and the correct flow proportions into the intake ports (centre plate inlets have smaller cross sectional area). If you fabricated the manifold yourself you could go for much bigger bends to give smoother flow into the block. Wouldn\'t be easy and you\'d ideally need a flow bench to test it but as I said, if you\'ve got the time.... :King

[yoeddynz]

I dont have a workshop dammit- and I\'m a fitter turner by trade so the skills are there (just mouldy) but alas...currently I\'m a cycle mechanic dealing to Oxfords cheap students bikes and no decent facilitys.
But i\'m going to build a workshop soon I hope then......
alex

[boyrotor]

So someone\'s done the maths to work out an equivalent to what the OMP puts out as far as premixing...?
I just wouldnt want to get it wrong.. although I could always just add more to be safe...
I do like the idea of being covered in case the OMP failed- and the idea of not having it and its little lines spoiling the veiw of such a nice lump..

Royal purle have done the maths for you - from their faqs;

A stock FD twin turbo 13B with the MOP oil injection system can typically use about one quart per 1500 miles under hard street driving. If this vehicle is getting 15 mpg, the gasoline to oil ratio is 400:1. If the oil consumption on this vehicle reduces to 1 quart per 2500 miles and fuel efficiency increases to 20 mpg, the gasoline to oil ratio increases to 600:1. The stock metering oil pump is a great system as it varies with throttle position (load on the engine). Pre-mixing has to be calculated for the ‘worst case’ that will be seen by the engine for that fuel load. Under racing conditions, that’s wide open throttle at racing rpms. This means that at idle, the ratio may be slightly fat (rich).

100:1 is actually a lot of oil, ok for a race car but i would say too much for a street car IMO.

Also as RP say above premix has the downside of forcing you to have a constant amount of oil in the mix, whereas the factory set up varys it.

[mullins]

Pre-mixing has to be calculated for the ‘worst case’ that will be seen by the engine for that fuel load. Under racing conditions, that’s wide open throttle at racing rpms. This means that at idle, the ratio may be slightly fat (rich).

In my opinion this statement flys in the face of common sense! With premix if you are drawing in more fuel you will also get more oil. The ratio will remain constant. At idle you will use less fuel and therefore less premix.

The stock metering oil pump is a great system as it varies with throttle position (load on the engine).

I think it\'s a crap system. If you use premix you will meet the increased demands of flooring your foot instantly whereas the OMP has to physically catch-up with the sudden extra demand. A case in point if you thrash your car and then stop at the lights you will sometimes see smoke (particualy on the mechanical OMPs) as the OMP lines are still carrying extra oil which is no longer required.

[oldone]

In my opinion this statement flys in the face of common sense! With premix if you are drawing in more fuel you will also get more oil. The ratio will remain constant. At idle you will use less fuel and therefore less premix.



I think it\'s a crap system. If you use premix you will meet the increased demands of flooring your foot instantly whereas the OMP has to physically catch-up with the sudden extra demand. A case in point if you thrash your car and then stop at the lights you will sometimes see smoke (particualy on the mechanical OMPs) as the OMP lines are still carrying extra oil which is no longer required.

Cant agree more ol chap...:cheers :cool

[boyrotor]

In my opinion this statement flys in the face of common sense! With premix if you are drawing in more fuel you will also get more oil. The ratio will remain constant. At idle you will use less fuel and therefore less premix.

Yeah the ratio will stay the same with premix, whereas the omp will vary it, thats what they are trying to say.

[yoeddynz]

So who of you out there in Rotary world \'premix\' and who uses the OMP? Just to get an idea....

[mullins]

I premixed 100:1 on my last 12A. It seemed to be a good balance.

[oldone]

Premix 100:1....have done so for 12 years:burnout :guinness

[yoeddynz]

With premix do they smell more \'smokey\' ?
And whats the easiest way to premix...oldone- you will have worked this one out after 12 years!!!
alex

[mullins]

If you use a marine 2 stroke oil thats designed to burn clean you shouldn\'t get much smell (rotaries tend to smell of burnt oil anyway). You can then run a good synethic oil in the sump.

Easiest way I found was to get hold of a syringe thingie with a measure on the side. My old man filled up for me one time and got a bit confused with the measure. He ended up putting in 200ml to 20 litres of petrol! I was surprised at how little a difference it made smoke-wise. I don\'t think it has to be an "exact" science. Era might have some better ideas. :chat

[Dominic]

Capacity of tank is what 50 litres ish, give or take. Just buy the 1 litre bottles of oil and chuck in half when you fill up. Oil will mix nicely in the tank after a few corners but if you want a really good mix I guess you could half fill tank, add half litre of oil, then top up. Just make sure you\'ve got a few spare bottles of nice oil in the car in case the petrol station has run out...

Mullins - Isn\'t 200ml of oil to 20 litres of petrol the correct mixture, i.e. 100:1?

[mullins]

Yeah sorry I meant 400ml. I used to put the oil in first and then the petrol to help stirr it up.