HOW TO: Swap Series 2 Renesis into a Series 1 RX-8
 

I just successfully swapped a factory new Series 2 Renesis motor into my 2005 Series 1 RX-8 race car. It was actually pretty easy to do. I'm not sure if anyone has done it before so I'm writing this thread as a "how to" guide.


First, WHY put a series 2 motor into your series 1? I'm not convinced there is any big advantage to this swap. The series 2 motor is supposed to have a bit better oiling system. Internally they are the same. The reason I did this was because I didn't want to spend the time to rebuild my motor (I'll rebuild it later and keep it as a spare) and I don't trust the "remanufactured" motors from the dealer. A brand new series 2 motor can still be purchased from Mazda Competition (or maybe even a dealer???) but the price is pretty high ($6200 from Mazda Comp last I checked). Or if you happen upon a good used series 2 motor from a wrecked series 2 car you are all set!


IMPORTANT: The only thing that you really can't swap over is the series 2 oil metering pumps. The series 1 ecu can't run them and I can't imagine how hard it would be to swap the full series 2 electronics. SO if you're doing this swap you'll need to eliminate the OMP and use pre mix only. Most racers agree on one ounce premix per gallon and MANY racers have good luck using only premix. Premixing would be a pain on a street driven car so you probably don't want to do this swap if your RX8 is not primarily a race car.

We shall see how long it lasts on premix only. I am curious.

Ok, if you have your hands on a complete used series 2 motor then you're all set. However, if you have a new series 2 "short block" motor from Mazda (Part# N3Y4-02-200A) you'll also need to purchase the following additional parts to complete the swap into a series 1:
Oil crossover tube (N3R1-14-210)
Oil crossover tube gaskets (N3R1-14-214 & N3R1-14-342)
Oil cooler lines (N3R1-14-710A & N3R1-14-720A)
Ignition Coil Mounting Bracket (N3R1-18-105)
Optional items:
Oil Dipstick and Tube (N3R1-10-440 & N3R1-10-450B)
Factory nuts & bolts (9994-00-801 X 2, 9979-40-825 X 2, 9994-00-801 X 6)


This will all cost you a few hundred more dollars

There are only a few minor modifications you need to do to make the Series 2 motor work in the Series 1 car:
1) The rear plate of the Series 2 motor does not have a mounting point for the oil pressure sensor that mounts on the Series 1 rear plate. Fortunately the oil crossover pipe which bolts into place where the stock series 1 oil filter pedestal would be has a plugged tapped fitting of the correct size. Simply remove the allen plug from the series 2 crossover pipe and install the series 1 oil pressure sensor there. Easy.
2) Since you'll no longer be using the Oil Metering Pump you'll need to plug the nipple that feeds the series 2 oil meters. This nipple is located near/under the ignition coils. I decided to crimp it shut and then weld it.
3) You'll need to plug the six oil injection holes in the housings. I just used some short M10X1.25 thread bolts with copper crush washers.
4) You'll need to use the Series 2 ignition coil mount bracket as the series 1 does not clear the extra series 2 oil meter junk on the front cover.
5) Install the two series 2 specific oil cooler lines, these will then attach right to your series 1 cooler lines.
6) You need to retain your series 1 oil metering pump and keep it plugged into the series 1 wiring harness. The ECU has to see that the oil metering pump is there or else you'll go into limp mode. Since the series 2 motor does not have the oil filter on the rear of the motor I decided to use this space to bolt the series 1 OMP to the motor. But you can of course mount the OMP anywhere you like that the wiring will reach.


And that's really it! Pics attached.

Some more pictures of swapped parts

From here all the series 1 parts will just bolt right up no problem. You might notice that the series 2 motor has the crank angle sensor in a different place. This is not a problem because the series 2 trigger wheel is adjusted to compensate for this. Simply install your series 1 crank angle sensor onto the series 2 motor and it'll work fine.

You can probably swap over the series 1 dipstick and tube but I just decided to go with the series 2 dipstick and tube (not expensive and easier to access). There are a few mounting points for the series 2 dipstick that the series 1 motor seems to lack so I just secured it with zip ties... kinda ghetto but works.


One a side note - if you have access to a lift it's much easier to drop the motor/trans out the bottom of the car than hoist it out through the hood. Having done it five times now (or more?) I drop the powertrain onto a roller cart in about 2 hours.

The car runs just great as expected with a new motor. I've put a few street miles on the car so far with no problems. I'll update later in the year when I dyno it and put some racing on it. I hope this thread is helpful!

nice! love the effort put into this. intrigued on how it will hold up

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It SHOULD hold up fine. I personally know several racers who have done tons of events and even 25 hour endurance racing with premix only and have found IMPROVED wear and reliability.

But yes, we'll see! ... I race in three different series so if it lasts more than a year it'll be doing better than normal for me! :)

Several racers running Renesis engines?

Yes, all Renesis motors. Robert Davis Racing (Director of Marketing for Mazda USA) runs an RX8 in enduro events including the 25 Hour of Thunderhill. They eliminated the OMP simply to not have to worry about oil levels during an endurance event. They are also claiming improved engine wear.

Mother's Racing runs several RX8s in sprint events and at least one of their cars is pre mix only with no bad results after many years.

Also, I believe that ALL the Star Mazda race cars (open wheel Renesis powered race cars) use pre mix only.

I am aware that particularly early on some racers did seem to have side seal failure issues in longer three hour races and thought that keeping the OMP helped reliability. It's possible - I'm not an engineer so what do I know - but long races are tough on any Renesis regardless due to sustained high exhaust temps.

In all honesty since I do pretty much just sprint races along with some long distance rally races where carrying extra two stroke oil is a pain I would probably retain the OMP if I could. But I'm fairly confident that pre mix will work just as well.

I guess we'll see like you said! I'll have several races in the next couple months to test it out...

Ah so you did some research then, I was just curious because in the other thread you were not so sure. That is good to hear.

The .pdf I have on the Star Mazda cars talks about a lot of specific things but no mention of premixing the gas and I cannot find a decent picture of a Star Mazda Renesis anywhere.

we have 35 hrs of racing on a series 1 engine but we dont use factory apex seals or water seals and have raised the oil pressure to 95 psi with webber jets in the e-shaft and we premix with pettit premix only its hands down best and works great

What are you talking about? Star Mazda has no OMP. Their spec fuel is delivered already pre-mixed.

Couldn't agree more with Magnus about dropping the motor/subframe out the bottom for swaps.

If we take a step back and realize that the real purpose of the OMP is just to control the temperature across the apex seals due to the rotational friction against the housing, then one could almost conclude that the OMP was just a pacifier to the consumer market so that they didn't have to premix. I'd be surprised to hear any legitimate racing team would be using an OMP (or factory seals for that matter).

Nope, but I have had my hands in a few wankel engine prototypes that were built by the last company I worked at for as well as the patents and documentation that supported the testing and findings from their development. Some neat stuff came out of that, one of which was IR imagery of the temperature hazards across single and multi piece apex seals with various forms of oil injections. Albiet the differences there were sustained rotational speeds far lower than a driven wankel engine (except for throttle up).

Im intrigued on where this is going though

All I could fine.

Why does every thread that mentions removal of the OMP turn into a bunch of crazy posts about pre mixing fuel etc? LOL! Anyway, if you don't want to premix then just keep your series 1 motor! Easy enough. I hope the swap info was at least helpful.

It's because of compelling and logical conclusions reached earlier in the Renesis's life span that haven't been refuted by anything substantial. Every instance of "but this person is doing it" has other caviates or unknowns that are critical to why they are able to, but are never ever explained.

I don't think a single one of us is against finding the reasons for why, and learning how to apply them, but none of us are willing to take a conflicting argument at face value "just because", and none of us have the resources to make a $5,000+ gamble to figure it out ourselves.

I'm not convinced it can't be done. I'm just convinced that there are other elements and factors that are simply not being mentioned or discussed by the people that have been successful. Elements and factors that are critical to why it didn't work before, and why it works now. I'm open to being wrong, but "because I said so" isn't a good way to get me to agree with you :) (whomever is the one arguing in favor of it)

Until that information is known, just making a blanket "it can be removed safely" would be extremely hazardous and irresponsible by anyone that new owners look up to for information.

we use both the omp and premix from the research i did the omp helps keep the side seals alive.i figure just leave it cant hurt any

Good work for posting that info . I hope you will come back later with some detailed info on engine longevity .

That would depend on who built it and when, which since 2004 when the series began using the Renesis engine there have been a number of different builders. They usually go at least one full season without a rebuild, but one notable builder told me he had some engines with several seasons still pulling high compression numbers.

The whole OMP vs premix debate is rather hilarious, but typical ...

I know some folks have made them work (speedsource?) but we only got a couple weekends out of a S2 motor running in an S1 car. Side seals gave up and the motor went soft after i think 5 races. Premix at 1oz per gal, no omp. I think the multiple (6 total) oil injection ports on the series 2 are pretty critical improvements in the renisis that offer better oiling than premixing.

I have run older 13B engines on premix (no omp) for years of racing and not lost any compression at all. It goes back to the side seal issues of the renisis...

Yeah, it's messages like this that keep me wary of simply calling it "ok to delete the OMP". There are 1 or more critical differences that enable some teams to get away with it and other not. Until those differences are spelled out, I won't ever advocate deleting the OMP.