Does anyone know how to get a mechanical OMP on a FD? Is it possible? I pulled mine off a long time ago and went with premix. Now I'd like to do the rotary aviation kit where the omp feeds from a tank thats filled with 2 cycle. The only problem is I no longer have the OMP harness in my car so I'd have to use a mechanical omp.

Any ideas???

Thanks

 

i may be wrong, but i think gordon monsen did something like this way back when. i want to say he used a t2 pump from like an 87-88. at least you have something to search on now

 

If you're interested, I can send you the MOP and associated stuff from a S4 NA.

Why not just do a "premix injector" system? Have a tank of 2 cycle oil in the back, feeding into the gas tank somehow, with either a crank or calibrated pump. Inject oil into gas tank, add gas. No mess, no measuring.

You'd have all the advantages of gas tank premix (whipped into the combustion chamber with the fuel instead of sort of dripped in) without the mess. Also, this arrangement would let you crank up the premix for track days or cruises or such - you really can't adjust the stock injection system easily, but if you know you'll be ripping up winding roads on the next tank of gas, you can inject more premix easily.

-=Russ=-

 

Damn that sounds like a great idea. You got any pics or links to this kind of set-up?

 

Nope. Just the idea. Planning to work on it next semester (once I'm done with school and have lots of spare time). I have a lot of RX-7 related projects I need to get rolling.

-=Russ=-

 

Yeah I think he did, also Poweraxel might know something about this I think. From what I've been told it's do-able but an "ear" or "tab" needs to be welded onto the housing? Don't really know but it has been done by a couple people.

 

I dont see how this would work. Maybe I dont understand what your saying. What I'm picturing is some type of injector system that instead of injecting it into the engine, its going to inject it in to the fuel tank? Is that correct?

If so that wouldnt work. The reason is you might be cruising along barely using any fuel with very low omp needs. You stomp the gas petal and go full boost and WOT. With your system the way I understand it is its now going to dump more oil into the fuel tank. The problem is that non of that oil is going to make it too the engine in the 5 second that I hit the gas petal. In addition now that I let off the gas petal and I'm cruising my tank is full of oil and I'm drinking down the wrong ratio of fuel and oil.

HOWEVER, what you could do would be something along the lines of a nitrous wet kit. But all that is too much BS to go thru and work the bugs out of

I think I'd rather just keep pre mixing or do the mechanical omp conversion that uses a 2 cycle tank but injects it into the engine based on rpm and load.

Thanks for taking the time though, its always good to hear people working on new ideas. If I just didnt understand what you were trying to say just repost it.

Stephen

 

No, I was just thinking of a system similar to what we all do now with premixing, just with less mess.

When you fill up, instead of dumping a bottle of premix in to the tank and then filling with gas, you push a button or turn a crank, dumping premix into the tank from a gallon container or such. Then, you fill up with gas, and your tank is at the proper 100:1 ratio (or whatever you happen to decide). While you're running, the system doesn't do anything except cart around some 2 cycle oil.

-=Russ=-

 

Ahhhh now I get it! That sounds alot simpler! Great idea!

Edit: If you haven't thought about this yet, you could use a solenoid (like for water injection) to close off the path from the supply tank to the fuel tank. That way the pressure inside the gas tank won't force the oil and gas back into your supply tank.

 

Or... a check valve?

Now, does anyone know where I can find small pumps and fluid measuring equipment fairly cheap?

-=Russ=-

 

Check valve would be cheaper. Does anyone make a decent sized one?

Also here's another idea. If the car is turbo charged you could run a vacuum line to the supply tank from the manifold. In this line you would have a one way check valve so that when you boost, that vacuum line will pressurize the supply tank. The check valve will make sure that the tank stays pressurized. With the tank pressurized all you would need to do is just push a button to activate the solenoid to let a measured amount of oil in the tank. This will elliminate any pumps. What do you think?

 

*blinks* And pressurizing the supply (which would most likely be in the rear of the car) with manifold pressure is somehow less complex than a small pump that could be powered off the tail lights? Plus, what about us NA guys? :-P

-=Russ=-

 

Well since I'm turbo charged I was pretty much thinking along those lines. If you use the tail lights, wouldn't the lights have to be on so that the pump would have a power source? Either way would work great. Just trying to give you additional ideas.

 

Yea, you'd have to leave the parking lights on while you were fueling to power the pump. That's the easiest way I can think of to get power back there. Beats running 12v from somewhere up front. Alternately, a hand pump (with a crank or such) would work too.

-=Russ=-

 

KISS!

why rely on some system when you can just dump some oil into your tank when you fill up?

 

You guys realize that pre mixing isnt hard right? lol

It only takes a few seconds to pour a small bottle into into funnel.

The only reason I want to do this isnt because of the pre mix "hassle". The reason I want to run a mechanical pump with tank of syn 2 cyc is so it will squirt right into the engine. I really dont see this as a problem though since I pre mixed for 10-11K miles and when I tore the engine down it looked awesome inside. I think the premix is working great but for some reason I just always wonder if its mixing good in the tank. I know it probably does since I put in the oil, then the fuel. That way it splashes around and mixes better.

Anyway, premixing isnt hard guys. Just get a funnel and bag to keep it in.

 

Sure it's easly to just pour in some oil but personally I hate pulling out the funnel all the time(especially when it freezing). Then you have to clean the funnel so that you leave less of an oil smell in your car. Like Syonyk I like to be creative with stuff. I don't currently premix much with my stock Fd but, when the 20b goes in, i'll have to do it more consistantly. With a pre-injection system all you would have to do is push a button. Even though it's really not necessary, to me it has some Pimp factor.

I personally really like Syonyk's idea and I'm seriously considering fabricating this set-up for myself when I install my fuel reservior.

 

Doesn't the fuel return line constantly return fuel to the tank when it bypasses the regulator? If so your premixed fuel will always be mixed.

 

i can see one big flaw (i was thinking of something like this a while ago)

how would you measure how much oil to dump in?

it'd be easy to measure it for a full tank, but what if you dont wasnt to fill it up all the way? or if you decide to fill it up when its still 1/3 full?

would be nice to be able to input how much fuel you put in and have an electric pump like thing that could spit out the ammount of oil that's good for a certain ratio (which caould also be adjusted for trackdays etc.)

it seemed like a hell of a lot of work.
and i personaly like the looks and questions that you get when you pull out the bottle of 2stroke and pur it in ur gas tank

 

Well, you either have a metering pump (1oz per push of the button, something like that) or, more likely, put a flow counter in the output. Reset the flow counter, hold button until specified number of oz have been transfered, stop.

-=Russ=-

 

As i understand it, a front cover from an S4 will fit with some modification. (There's something that has to be ground down for a good fit.) Then, you can use the S4 mechanical OMP. This was suggested to me by the Hitman (from Australia), but I haven't tried it myself.

Alternatively, some rotary aircraft folks have an external OMP with it's own tank. I don't have the url handy, but some searching can probably turn it up. If not, get back to me, and I'll dig for it.

 

I know that's possible to do and would work but it sure sounds much more complicated than need be. Besides, any premix system is always going to insist you premix at the worst case scenario ratio. Sticking with an actual OMP (even a mechanical one) is a much better solution IMO. For a race car I think premixing would be fine, but on the street the car is in constantly changing conditions and performance situations. Premixing works, but an OMP system works better.

 

You still only get the needed amount even with premix. Your fuel injector duty cycles change and the amount of premix (since its mixed with fuel) changes with the duty cycles just like the fuel does so it is a constantly changing amount thats injested based on load.

The only way I'd rather run the OMP system versus premix is if it was using a seperate tank that ran off of 2 cycle synthetic. And honestly I dont really see that as being much better now that I've seen with my own eyes that premixing works.

Stephen

 

You're making the assumption that the stock OMP systems inject oil at the same ratio as the fuel under all engine conditions. This isn't true.

Premixing all the oil in the fuel will certainly deliver more oil when more fuel is delivered but the ratio of oil to fuel will be constant at all times. The stock OMP system allows the ratio of oil vs fuel to vary and so will use less oil than strictly premixing.

 

I wonder if the stock omp ratio is based on stock internal pressure levels which increase as you make more power making the stock ratio inadequate?