Looking for recommendations. Is 87 ethanol free suggested? Also. The OMP has been removed from the vehicle I am going to be looking at. Any recommendation for a good pre-mix? I see pettit racing sells an additive. Thoughts?

Thanks,
-M

 

Up here at Denver's altitude, I run "low-test" fuel in my NA...I think it's 85 octane.
If the engine ain't pinging, use the lowest octane you can.

Not sure about premix but am curious what engine management your intended car is running to allow for OMP deletion.

 

That will be a very good question for the owner when I go to take a look. The price is a bit high, however it's very well kept and tasteful modification only. So i am curious to see it. Which is had a LSD.

https://ocala.craigslist.org/cto/d/m...330699658.html

 

Yeah, that would be the first question I'd ask because standalones ain't cheap but he makes no mention of it in the ad.
I suppose you can remove the OMP from the engine but leave it connected and the stock ECU would be fooled...but what's the point?

 

the OMP lasts almost indefinitely once removed from the engine, but you can't put a faulty OMP on and then have it still functioning off the engine. better in that case to install an Rtek chip to bypass the OMP limp mode.

the S5 OMP is an abortion and they are just going to continue to fail, ever priced a new one?

http://www.mazdatrix.com/getprice.as...m=14-600B-N350

that part doesn't feel like a nearly $2k investment to me. i'd premix for the life of the car and still feel like i was saving money, as well as treating the car better.

 

that is a clean car, you can see the OMP bolted next to the airbox, so its stock ecu.

if that was mine i'd just put it back to stock, i'm too old to premix unless its a race car, and even then...

on a stock ECU, 87 is totally fine.

 

What is your sample size that lead to this conclusion?
My experience is exactly opposite but only based on two engines, the first of which had a documented 300k under it's belt and was almost spotless when disassembled.
No idea about the second engine but she runs fine as well.

 

check the forum, you will see thread after thread of S5 omp failures, im not sure who you think they are uncommon. i've seen probably 20 failed OMPs out of roughly 50 series 5 cars so it's not really a rarity. it is however almost directly related to ambient heat conditions, so if you live in an area that rarely gets hot, you may have less failures.

sure, you can pretend the problems don't exist and skate through life being hopeful, or realize the potential issues and be prepared.

once your OMP has failed, it can possibly take the ECU out with it and once it has failed you also then have to find a good working one. which is a much more daunting task than it sounds with less than honest sellers and those who are selling untested used parts, or parts that have failed while sitting on the shelf for 15 years. luckily the harness and ECU failures are much less common than just the OMP itself going out.

 

Great information, thank you guys very much. When I see the vehicle I'll take a look and ask exactly what he's done. Also would like to know which Oil he has been premixing. Hopefully nothing that leaves a massive carbon buildup.

-M

 

I appreciate your points but "check the forum" is a terrible attempt at proof.
The majority of FC owners I've run across in a decade of ownership are at best, infrequent visitors to this site. I doubt most are even registered.
So I'm thinking this forum consists of a fairly distilled group to begin with and how many people are going to initiate a thread like "Hey! Just wanted to let everybody know my OMP is working great...".
In other words, the only time we talk about a part is when it fails and by that standard, every single component of the car could be considered an "abortion".

To the OP...
I didn't spot the relocated OMP but that does indicate that the unit still functions or you'll be in permanent limp mode. I would check to see exactly how the deletion was performed- there are air lines and injector nozzles to be dealt with as well as the mount on the front cover. If at all possible, I'd look into restoring the OMP system complete...I hated premixing the Sonnet and definitely am too old for that **** today.
If premixing doesn't bother you and carries the faint whiff of "racy" then go for it....it's certainly the only time you'll feel raecar like in a stock-ish NA FC.

 

yeah well i've personally seen plenty of them fail, but i guess that's not proof enough either. far too often for them to be considered a reliable piece of equipment, though the FD and RX8 OMPs are much more reliable and fail much less often.

and when the S5 OMP fails it has the potential to take out the ECU too, but i think i already mentioned that.

 

Again, I did not mean to disparage your experience and apologize.
I have a hard time with my input because I have a lot of experience with my particular car, not with many.

 

Clokker you make me hopeful I'm not on borrowed time. My OMP has 300k+ mile on it. I figure when it goes/ if it goes before I get a standalone I'll get one then as a PFC or Adaptronic is cheaper than an OMP.

As for premix sometime I will in addition to the OMP when I feel like it. I just use Super Tech or Evenrude I get at Wal-mart. One nice thing about the OMP is if I run out of premix or don't feel like it at that fill up I don't bother.

 

i used the fuel injected two stroke at wally world. 2 oz per gallon.

 

Would e85 be acceptable on stock s5 N/A and stock ecu?

 

no, not even close. if you tried you probably wouldn't even get 100 feet from the fuel pump before the car becomes undrivable.

 

Good to know!! I have 87 Ethanol FREE fuel readily available nearby. I'll stick to that when AND IF I get this car.


Thanks for the quick reply.
-M

 

youre way overthinking this, ethanol free is more or less a waste of money. ethanol free fuel is good for small engines that sit for extended periods of time. E10-15 is perfectly fine for almost any automobile, including these. and higher octane offers no benefit to the non turbo rotaries either, so again waste of money.

 

On the octane note, it's almost as big of a deal as oil choice in rotaries. You'll have people arguing to no end about which to go with and what's better than the other.

I personally run 91 non-oxy (no ethanol) in my carb'ed 84 FB with a 13b, and 93 octane with ethanol (normal fuel) in the RX-8. Haven't had issues running either of the vehicles with those specific octanes.

On this car you would be fine running fuel with ethanol in it so long as it gets ran during the winter every couple of weeks and doesn't gum anything up in the fueling system.

 

no, the ECU won't have any way to know its E85, however...

if you ONLY ran it on E85, you could simply put in larger fuel injectors, and pump and it would probably work. it needs about 30% more fuel, so i think stock T2 stuff still isn't quite enough.

 

The factory specification calls for a minimum of 87 octane using the (R+M)/2 method, and a maximum of 10% ethanol. If the engine is out of tune and/or in bad shape then you may need to use a higher octane to prevent knocking, otherwise higher octane fuel is just a waste of money. Lower octane fuel can be used in high altitude regions if the engine and tuning are good. Alcohol has a low energy content, which means it will yield less power per pound, and therefore the less alcohol the better the performance of the engine. I recommend using Top Tier gas to ensure that lower octane grades of fuel have the clean-burning characteristics that the big oil companies would like you to think is only available in their most expensive high-octane fuel: Home | Top Tier Gas

For premix, it is generally better to use oil that is sold for this purpose (see Pettit, Racing Beat, Mazdatrix, Atkins, or other rotary engine dealers). Oil made for two-stroke engine premix will also work, although it may not burn as cleanly as the oil sold by rotary engine shops.

+1

That car looks like it had a good owner. The listed modifications are good-quality desirable items, and the car also has an aftermarket exhaust and strut tower bar. It also has nice all-weather touring tires that you could use for autocross events. I have a similar AGX/Ziex setup on my convertible RX-7.

 

Thank you for the reply, it's also very well priced at about 5000 less than a Mint 10th anniversary addition I'm looking at in Miami right now, I'm in a huge tossup between owning a turbo or an NA with significantly less problems potentially

 

It's priced a bit high, but that is to be expected for an asking price. Actually, if it has an upgraded AC system, all-aluminum aftermarket radiator, new driveshaft, aftermarket power window relays, new pulsation damper, new fuel pump, and/or other commonly-replaced parts, then $5K may be a decent price. Be sure to read Aaron's buyer's guide: How To Buy An '86-'92 Non-Turbo RX-7

The 10th Anniversary model has no collector value at this time, so don't get suckered by somebody who is trolling for morons. A truly mint FC RX-7 would be undriveable due to 'dry rot'.

There is not a significant difference in 'problems' between the NA and turbo FC models. The FD models are the high-maintenance queens. I recommend that you just buy a nice FC RX-7 (with a good body) regardless of which model, trim, or options it did or didn't have when new. Don't put any money into it unless necessary, and after about a year of driving it and reading this forum you will be able to better assess what you want to do in the long run. It's a car that you can easily sell whenever you like, not a marriage until death do you part.