OMP vs Pre-Mixing

[SteveO]

Im making plans for my rotary car chassis purchase (hopefully a RX3). Ive put alot of time, money, and blood into the engine I have built but am undecided on what to do about my oil.

Ive always pre-mixed my rotarys and kept the OMP also. The premixing is a back up in case of a faulty OMP, or it just decides to take a crap on me. I lose a few octane, but its not a big deal.

But, dumping MMO into your tank everytime you fill up gets old. Especially having to keep a bottle in your car.

So now, I have an option to rebuild and peice together a new OMP for whatever car I do get. I have some of the parts already, and it will be an easy job.

But Im still not sure if Ill be comfortable. All it takes is that pump going to shit and all the hard work I have done is out the door.

Suggestions? Opinions?

(Also, I have always used Marvel Mystery Oil. I cant stress enough how well this stuff works. When I did break into my GXL motor it was so clean it wasnt funny.)

[Riken]

Im making plans for my rotary car chassis purchase (hopefully a RX3). Ive put alot of time, money, and blood into the engine I have built but am undecided on what to do about my oil.

Ive always pre-mixed my rotarys and kept the OMP also. The premixing is a back up in case of a faulty OMP, or it just decides to take a crap on me. I lose a few octane, but its not a big deal.

But, dumping MMO into your tank everytime you fill up gets old. Especially having to keep a bottle in your car.

So now, I have an option to rebuild and peice together a new OMP for whatever car I do get. I have some of the parts already, and it will be an easy job.

But Im still not sure if Ill be comfortable. All it takes is that pump going to shit and all the hard work I have done is out the door.

Suggestions? Opinions?

(Also, I have always used Marvel Mystery Oil. I cant stress enough how well this stuff works. When I did break into my GXL motor it was so clean it wasnt funny.)


Do you have pic of the motor that you used MMO?
I have read pros and cons about MMO. I did buy it but im only adding about 1oz plus 3 of the 2cycle oil as part of my premixing.

Ive seen where you can actually take the MMO and have it get the oil from its own can. In that case you wont have to really premix, you can add anything to the can and not to the gas tank....

[SpooledupRacing]

I go to walmart and buy TCW3 2 cycle oil.. no need for MMO... I use .5oz per gallon with the omp on and 1oz per gallon without an OMP.

IMO hands down remove the omp and just use the 2 cycle.. the internals will be cleaner and in the long run may give u a healthier and longer living engine...

[wes.pro5]

i'm pulling mine when i rebuild the motor just for the fact that the weather here is really hard on an engine during the summer and i need a heavy synthetic to keep it in good shape. on the stock OMP, i can't safely run a heavy synthetic, so this is kind of the only solution. if there are extreme weather conditions where you are (i understand that there are in Alabama) i recommend going ahead and pulling it to run a premix.

[SteveO]

Riken, no I dont. It was my second rotary rebuild I had ever done and didnt even consider taking photos. The engine had 17XK miles on it, but it was very very clean. I was extremely suprised. (My first rebuild was a 12A and there was no comparison...the 12A was deplorable.)

Wes, yeah...we have crazy weather, but its not to bad on rotaries.

Thanks for the input. Im pretty sure Ill be premixing.

[9K Redline]

For now, a lot of things I say on this forum will be things I learned from my other 8 friends that have modded and unmodded cars. That said...

The 8er I know with the Pettit SC premixes all the time (before the SC) and when it popped, lubrication was the equivalent of being drunk and taking a leak on a wall and not hitting the toilet, hit or miss. However, I am still not really versed on how the OMP and injectors worked for the 7. I just don't understand why the RENESIS is having such problems when there were really none for the 7. Oh well...my .02.

[SpooledupRacing]

The 7's did have problems..

86-88 RX7 have a MECHANICAL omp.. it never failed

89-92 all FD and 8's have an ELECTRICAL omp.. which go bad and without warning..
Running 2 cycle in the gas along with the omp or removing the omp and running full 2 cycle is the best and safest policy..

[9K Redline]

The 7's did have problems..

86-88 RX7 have a MECHANICAL omp.. it never failed

89-92 all FD and 8's have an ELECTRICAL omp.. which go bad and without warning..
Running 2 cycle in the gas along with the omp or removing the omp and running full 2 cycle is the best and safest policy..

I was aware of the mech. vs. elect. but I thought the 3rd gens had a mech OMP as well. Other than "putting in the exact amount of oil needed" what are the benefits of electrical over mechanical? Everything I read says the mechanical OMPs were awesome, as you said.

[SpooledupRacing]

I may be wrong on the FD omp.. I was only told they were electrical.. I will look into it and verify

the only benefit is that the electric was tied into the ECU and when they "failed" the car would go into limp mode.. HOWEVER this does not always happen (normally only when unplugged)

It was just Mazda trying to "be more hi tech" It failed.. and no they did not learn.

the electrical did not put any more oil in the the mechanical did.

[SpooledupRacing]

ok I looked at a schematic and I do think it is electrical.. I also see that dealer list for an FD omp is 2000.00 CAN U BELIEVE THAT!!!

[SteveO]

The 7's did have problems..

86-88 RX7 have a MECHANICAL omp.. it never failed

89-92 all FD and 8's have an ELECTRICAL omp.. which go bad and without warning..
Running 2 cycle in the gas along with the omp or removing the omp and running full 2 cycle is the best and safest policy..

84-88 13Bs (with some 89s)
and all 12As had mech pumps.

They had lots of issues. Especially if you didnt use decent oil. The pumps would get clogged and gummed up. Some would even just wear overtime and have to be rebuilt or done away with.

[9K Redline]

2k for an OMP...wow...I'm scared to see how much mine is. Thanks for clarifying. I plan on buying a 3rd gen 7 in a year or so if all things go to plan. So I'm trying to get versed.

[SpooledupRacing]

I will be pulling the omp off of every rotary I own

[jungleagent]

2k for an OMP...wow...I'm scared to see how much mine is. Thanks for clarifying. I plan on buying a 3rd gen 7 in a year or so if all things go to plan. So I'm trying to get versed.

Why? Don't do it. Great cars but come on pal 16X is coming out in a few years. Mod the living sh*t out of your bad ass 8 and move forward. Not backwards.

[Riken]

Yeah so your trading the 8 for a 3rd gen?

[SpooledupRacing]

wait wait...

The FD is by far more superior then the 8 I have to admit.. not only was the styling better, the motor put out more power (more reliabe) etc..

The 8 is a very nice car but the FD is by far prolly the best 7 ever made and IMO unless u get a cosmo it stands on a pedistal of its own..

I still think the 7's are more pure to the game.. they are the "race" car where the 8 is a family sedan.. the new 16X will be in a family sedan too.. Its a shame.

[SteveO]

While the FD is nice, I cant consider it the best 7 made by far.

Cheap ass interior, massive reliability issues due to the twins, and some pretty crappy exterior parts. (you havent really lived until youve had a FD door handle fall off when you grab it)

The GXL was, IMO, the best 7 ever purchasable. Amazing reliability, great handling, was made beautifully with alot of time in the car.

While the FD put out alot of power, it sacrificed alot in return.

I dont own an 8, but have been looking into them awhile. (Especially with the low re-sale value...2004-5 for $11-14K now) But they seem like good cars. I have heard about rampant flooding, but thats with any rotary. As far as other reliability issues, I havent researched enough to know anything about that.

[SpooledupRacing]

did u not forget that the FC door handles break ALL THE TIME

my pass side is broke now it has been used maybe 10 times since I owned the car..

all the interior is cheap.. have you ever pulled anything off of the interior on a 7 it all breaks (radio surounds, triangle vents)

[SteveO]

did u not forget that the FC door handles break ALL THE TIME

my pass side is broke now it has been used maybe 10 times since I owned the car..

all the interior is cheap.. have you ever pulled anything off of the interior on a 7 it all breaks (radio surounds, triangle vents)

Thats the issue though. For what the FCs cost, I can deal with that. If Im paying $10k+ for a decent (non-modded, manual) FD my door handles better not break off in my hand! :zx11pissed:

[SpooledupRacing]

remember what the cost of the cars was new.. basiaclly the same..

my 86' base was 25K brand new..
the FD's were what 28K new

the only difference is the valve of the FD is higher because people like them.. but down to earth they all started with close to the same figure..

[9K Redline]

Allow me to clarify, I will never trade my 8 for any car. I love her too much. The plan is to mod the 8, but I want the 7 for it's legendary prowess and massive hp potential along with the extra sex appeal. ;)

Now, on topic with everyone here. The 89 NA 7 my uncle had was pretty well put together. I never noticed the cheapness of it, I always thought it was a kick ass car.

On the reliability aspect of the FD. When it came out, yes there were lots of issues, rubber hoses melted, flooding, housings crapped out at 75k due to the excessive heat issues, and the list goes on. However, with current technology we can solve those issues and make the FD more reliable (within reason) depending on how you build and take care of the car. You want a 600+hp beast then you'll get 50k out of the motor. However, if you keep the car close to stock form or go single and boost the same, you save the housing and heating issues, thus becoming more reliable. The only thing that makes me nervous is that an FD is still a money pit. So, I'll see how I feel in a year.

I love the styling of my 8 and will make it a cleanly modded sexy beast within due time.

[JoseRotary83]

I had no idea my FC had a Mech OMP. Now I love it more. To bad my cousin has the FD wish is electrical.