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Premix with blocked OMP, OMP with external reservoir or OEM OMP for trackcar?
Hi,
I'm planning on using my FD primarily as a trackcar, only some drives to and from the racetrack at cruising speeds and some weekend journeys.
The engine is out at the moment for a rebuild and I had plans to modify the OMP for an external oil reservoir for 2 stroke oil and use fully synthetic for the engine and turbos. I thought that would be the best solution lubrication wise and in terms of carbon buildup.
But now I'm reading more and more that modern synthetics are absolutely fine when burning them in the engine and that some even produce less carbon buildup than the "highly praised" mineral oils or dino oils.
So I'm totally confused now what to do. I want the absolute best solution for my engine, it doesn't matter if its complicated to handle (e.g. frequently filling the external reservoir) or to build.
Maybe here is someone who has inspected different engines from inside that ran different methods and can say which is best?
- Premixing, OMP untouched (What would be the best ratio?)
- Premixing OMP blocked off (What would be the best ratio?)
- OMP modified for external 2 stroke reservoir
- none of the above, just doing it as Mazda intended
IMO "the best" is premixing + external OMP. That said, it may only be marginally better than premixing alone with the stock OMP or even any OMP for that matter.
First, the OMP only drips oil at the nozzle. This doesn't fully spread across the rotor face.
Second, the benefits of an external OMP vs stock are minor IMO. Yes you are not burning cruddy engine oil but is that a big deal, probably not (and more so if you change your oil frequently which you should be doing anyway on a track car). The other touted benefit is you can run synthetic with an external OMP because synthetic doesn't burn. That's pretty much rubbish.
Third, running an external OMP is both complicated and expensive (you need an RA OMP adaptor (if they even make them any more), a Mikuni OMP, and an external tank). And don't forget to keep the tank filled.
All that said, I run an external OMP because it's "the best"
But yeah, since I will change my oil very frequently (With my last track car I changed it yearly or after 2000-3000 miles and I think I will shorten that with the FD) going stock OMP plus premixing should work just fine.
Just running pre-mix, when injector duty goes to zero, so does your hard seal lubrication. Something that will happen frequently and from relatively high rpm on the track. If you have a PFC and a datalogger it is possible to compensate for that. Not certain about the other standalones.
The OMP is rpm and load dependent.
I'm premixing only right now and it's really no big deal, but my concern is the same as your Guy's, no lubrication on decel in gear. I'm planning to add the omp back in the near future.
Our '94 is running TC-W3 premix at 8 oz/tank fill (about 14 gals). This is during initial break-in of a new engine. Does this sound about right? OEM OMP with new lines, street use only. Roughly 100 miles on the engine at the moment.
Type of oil good? Amount about right? Or should I use more oil?
^IMO that's fine. Although for clarification/avoid possible confuston, the fuel capacity of an FD is about 20 gal. IIRC. But ABOUT .5 oz. @ gal with a working OMP is the accepted rate.
Carbon buildup on a race engine? It's not nearly as big of a concern as all the other things like cooling and knock. I wouldn't sweat the details.
^^ I'm going to give a similar answer. It's a new engine. Your OMP is working. If it weren't working, the stock ECU is smart enough to go into limp mode (NO OTHER ECU is as smart as stock for running the OMP). Premix if it gives you peace of mind, but it is totally unnecessary. Your first engine lasted 24ish years and over 100k miles. Don't sweat the details.
i would tell your wife to drive it like a normal car at this point, or maybe be easy until 500 miles if it gives peace of mind. Giving her premix ratio formulas or you filling the fuel for her so it's done "correctly" is a needless hassle.
the stock oil change interval is 5000 miles for light duty use, and you'd be surprised how little oil an engine needs to run... that's why the idiot light only comes on when you are way down. The point is, you're not getting much benefit by doing extra things.
Premix if it gives you peace of mind, but it is totally unnecessary.
Yep, necessary for my peace of mind (I admit to being somewhat OC). Also Yoshiya recommended 2-stroke oil at about this concentration, even over the life of the engine. Although he personally uses engine oil (Castrol GTX 10W-30).
Our fill-ups are almost always close to 14 gallons. Car has never run until dry (20 gallons fuel capacity). I change oil at 3K miles, just from habit.
I've tracked the same FD engine for 8 years now. Using stock OMP and supplement about 0.5 oz/gal Idemitsu premix when at the race track.
You're going to want to change your oil much more frequently than your past track cars and that will help ensure you're injecting good oil via the OMP. I change my oil every other track event. The car sees only about 10-20% street use.
Cam at Pettit Racing has always recommended adding premix to the gas tank even with stock engines with working OMPs. He said it really extends the life of the engine.
For ease of use on a street and track car I suggest my setup: modify the OMP to use an external tank filled with either Idemitsu premix or other racing 2 cycle oil, and fill the tank with premix at a minimum of .5 oz per gallon. This way you can still drive the car on the street without gas tank premix if needed.
Cam at Pettit Racing has always recommended adding premix to the gas tank even with stock engines with working OMPs. He said it really extends the life of the engine.
Yoshiya, the mechanic who installed our '94's new engine, said the same thing.
...It's a new engine. Your OMP is working. If it weren't working, the stock ECU is smart enough to go into limp mode (NO OTHER ECU is as smart as stock for running the OMP). Premix if it gives you peace of mind, but it is totally unnecessary. Your first engine lasted 24ish years and over 100k miles. Don't sweat the details.
i would tell your wife to drive it like a normal car at this point, or maybe be easy until 500 miles if it gives peace of mind. Giving her premix ratio formulas or you filling the fuel for her so it's done "correctly" is a needless hassle.
the stock oil change interval is 5000 miles for light duty use, and you'd be surprised how little oil an engine needs to run... that's why the idiot light only comes on when you are way down. The point is, you're not getting much benefit by doing extra things.
IMO MAZDA was between a rock and a couple of hard places when it came to hard seal lubrication, emissions and your average turn-the-key-and-go owner in the 90's. It's not beyond the realm of possibility that the engineers advocated for lubrication... either by pre-mix or via the OMP. But compromises had to be made among those conflicting considerations. Happily we're not turn-the-key-and-go owners anymore. We're enthusiast owners. I've been a practitioner and advocate of pre-mix with OMP since about 2008 after a rebuild with new housings (also added WI about the same time). And I'm not baking a cake at the pumps. I know about how much gas it's going to take to fill-up and guesstimate how much 2 cycle to add. Takes maybe an extra minute. Do as you want, but honestly I can't think of a downside, but see a whole bunch of upsides to pre-mix with the OMP. It wouldn't hurt to re-consider on your part...IMO.
I've tracked the same FD engine for 8 years now. Using stock OMP and supplement about 0.5 oz/gal Idemitsu premix when at the race track.
You're going to want to change your oil much more frequently than your past track cars and that will help ensure you're injecting good oil via the OMP. I change my oil every other track event. The car sees only about 10-20% street use.
How long are your track sessions? Mine will only be 1- max. 2 hours of driving, so changing the oil after every event seems a bit like overkill to me. Plus, in the past I've been doing 7 to 10 events a year, so this would be pretty pricey, assuming that I should change the oil filter every time too.
I thought it would be enough to change the oil every 2-3 events so after 4-6 hours of track driving.
How long are your track sessions? Mine will only be 1- max. 2 hours of driving, so changing the oil after every event seems a bit like overkill to me. Plus, in the past I've been doing 7 to 10 events a year, so this would be pretty pricey, assuming that I should change the oil filter every time too.
I thought it would be enough to change the oil every 2-3 events so after 4-6 hours of track driving.
Sorry for the confusion. My statement of "every other event" probably didn't translate well. That means I go 2 events on one oil change. I also go 2 oil changes on one filter since they're relatively short. So 2 track weekends on one oil change (end up adding from cat can loss during) and 4 weekends on a filter. Pretty cheap compared to other consumable costs. With heavy track use you'll find the oil gets so much fuel dilution you shouldn't go further on intervals anyway.
I run between 20-30 min sessions depending on the group I run with and between 8-15 sessions in an event.
Sorry for the confusion. My statement of "every other event" probably didn't translate well. That means I go 2 events on one oil change. I also go 2 oil changes on one filter since they're relatively short. So 2 track weekends on one oil change (end up adding from cat can loss during) and 4 weekends on a filter. Pretty cheap compared to other consumable costs. With heavy track use you'll find the oil gets so much fuel dilution you shouldn't go further on intervals anyway.
I run between 20-30 min sessions depending on the group I run with and between 8-15 sessions in an event.
No, thats just me, I'm still learning and didn't pay enough attention.
Wow, thats a lot of track time. How many events do you do over a year? Just curious.
07-25-17, 06:39 AM
