Larry's N/A streetport Renesis/13B Hybrid build

09-29-2023, 04:52 PM

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laurier.lg

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Larry's N/A streetport Renesis/13B Hybrid build

Hello fellow rotor heads !

New-member disclaimer:

Spoiler

So onto the goal of this post: I would like to use this post to share my my experience so far with my hybrid Renesis/13B setup, after running the car successfully for 2500 kms. I will post updates here as I drive the car more and more, and some videos will come.

I'll start by describing the setup that I have, and I'll then explain my experience with it.

Engine setup:

Housings & Plates:

Irons/Plates: The engine has RX-8 irons, street ported using the Mazdatrix template.
Housings: GSL-SE rotor housings, part# 10-100C-N304. These were bought brand new. If you want to run a similar setup, these housings should still be available through your Mazda dealer, otherwise they are available through Mazdatrix (at the time of writing this.)

Rotors & Internal seals :

Rotors: The engine was built using Renesis Rotors
Corner seals, Side Seals, Oil control rings, etc.: OEM internal seals & springs, except the Apex seals.
Apex seals: I have run Renesis RA Super Seals. See below for a full explanation on why I did not run wire cut RX-8 rotors with RX-7 Apex seals.

The big question: why I did NOT wire-cut the rotors and run RX-7 seals, you may ask ?

I had initially bought this engine already built. The builder made what is, in my opinion, a slightly questionable choice. They did not wire cut the rotors for RX-7 Apex seals. This has been haunting me in my sleep for the entire downtime of the car (basically ever since I got the engine back in and was working on the rest of the car -- cooling system, radiator, transmission, electronics, ignition, etc.) However: After careful research and after asking multiple people whether they think the Renesis-style Apex seals would work with a peripheral exhaust setup, I realized that there is a fundamental issue with running RX-7 seals in a Renesis: what corner seals to choose ? In a lot of instances, the RX-7 corner seals (made of rubber) get clipped by the side intake ports. I would only assume that the exhaust ports would make this worse. Some people that I've discussed with simply said to use solid corner seals and send it, but I'm not trying to get lower compression than on the engine I've just blown, so I won't use those

The ideal solution would be a special, RX-8-Style corner seal, but that would be wire-cut to fit RX-7 Apex seals. IR Performance, a rotary shop in New Jersey, seem to sell this style of corner seal: a metal, two-piece corner seal, but that is somehow deep enough to fit RX-7 apex seals. Here is the link to the product page: https://shopirp.com/products/irp-2-p...b-corner-seals -- however, at the time of posting this, they do not seem to have any in stock.

Also: an important thing to consider, is that the engine was initially built by someone who wanted to run a turbo setup, however, they ended up selling me the engine, and I did not (and still do not) plan to run any kind of forced induction in my RX-8. My goal is to run an OEM+ setup, keeping most of the stock RX-8 spirit, but adding the exhaust note and uniqueness of a hybrid build with GSL-SE housings.

Another point to take not of: every single person who has told me not to use Renesis Apex seals with peripheral exhaust ports, has never tried running such a setup. No one has ever been able to prove me that they had tried, and failed.

So: in the end, to keep things simple, despite most people recommending not to use shorter Renesis Apex seals with a peripheral exhaust setup, I decided that I would run the setup as-is, with the Renesis RA Super Seals. This was decided because I needed a car to get to college until my daily is out of the shop for its major repairs. For that reason I decided that I would run the car like it was built for now, and that I would wait and see how viable the setup is with the RX-8 Apex seals. I'm basically a guinea pig for future Renesis/13B hybrid engine builders.

Onto the rest of the build:

OMP situation & oil injectors: OMP-delete, running full premix, at around 500ML per fillup (around 100:1 ratio). The injectors are blocked using bolts; teflon tape has been used to help for air-tightness.

Knock sensor provision: On all 89+ engines, the knock sensor provision is located on the rotor housing. On pre-89 engines, it is located on the center plate. As such, I had to resort to a custom solution -- because the engine is running post-89 plates (without the knock sensor provision), and pre-89 housings (without the knock sensor provision). Fortunately, on our center plate, we have an old provision, that seems to be left from pre-89 casting, that we can use to mount our knock sensor, and not have the ECU/PCM be tripping *****

This provision is located near the oil filler neck, however a hole does need to be carefully drilled and tapped in order to mount the sensor.

The knock sensor provision in the centre plate, after drilling and tapping.

The primary injectors have been changed from reds to yellows (now, all injectors are 400CC. ECU has been adjusted to reflect the higher output of the primary injectors.

And the pièce de résistance, the exhaust manifold:
For my exhaust manifold, I'm running a log-style custom manifold, 5 short runners going into the same 2.5 inch exhaust pipe. Not looking to make extreme amounts of power with it, just looking to see how viable the setup is. Also, I like my cars quiet, so I'm pleased with this setup as it is. I have 2 O2 sensor bungs, because I need one for my AEM wideband sensor & gauge, and one for the ECU to get its readings.

In the following pictures, the O2 sensor provisions were not on the proper side. The morning after taking these, I had to send my manifold back to move these, because the one that's at 2 O'clock was hitting the transmission tunnel.

Here is how the manifold looks from the side

It looks like a badass piece of craftsmanship.

the 5 runners are made from a mix of 90- and 45-degree bends, from schedule 10 stainless steel piping that I bought at a plumbing supplier.

Rest of the setup:

I'm running a Mazdaspeed Cold Air Intake (that currently has a kink in the piping near the filter, lol), an Agency Power dual-resonated midpipe, as well as a Fujitsubo Legalis R catback exhaust system.

I'm running D585 ignition coils (OEM, directly from ACDelco). ECU has been adjusted for the longer Dwell timing of these.

The injectors have been upgraded to run all yellow injectors, in order to accommodate the original builder's intended turbo setup, and I left them as-is. The ECU has been adjusted for this by our rotary tuner from around the Montréal, QC area, Derwin Performance.

Some pictures of the install for your viewing pleasure.

The engine in question, with a little pipe for the oil return line from the turbo (deleted this, I just put a cap on there.

Just before putting it in.

Finally dropped in, back in early June 2023.

My thoughts so far:

As of now, I've driven about 2600 kms with the car in its current form. I haven't had any major issue, and as such, I could say that for such a project, my experience could be described as near flawless.

In terms of low-end torque, it has been improved by a pretty good margin. I'm not sure whether this is due to the exhaust setup, the streetported intake, the injector setup, a combination of these factors, or even just because of the fact that my old engine was really beat-up and was getting very tired.

The overall engine power, throughout the entire rev range, has also been bumped up coming from my old engine. I'm only having a small issue with the tune at the moment -- under certain conditions, the car reports "system too lean" DTCs, but I'm practically always around 14.7, according to my AEM gauge. A friend of mine who's a master tech (and has been a master tech in other dealers in the past) has diagnosed a faulty upstream O2 sensor, which I've ordered and received. I'll change it tomorrow and report how well the car runs after that. Our hypothesis is that my O2 sensor had fouled when I had my engine failure, which seemed to be a blown oil control ring. I burned just under a gallon of oil that day, so it might indeed have fouled the sensor. I'm also suffering from a *very occasional* misfire when I bring the RPMs above 6.5-7k. The higher I bring it in the RPMs, the worse it misfires. I think the issue might be related to the mixture which currently seems runs a bit right when we go up in the RPM range, according to my AEM gauge.

The best part is: the exhaust setup has reduced the amount of exhaust drone in the car when on the highway. I'm not sure if it's the exhaust manifold, or the fact that it might be better installed with less leaks and such, but regardless, that's what I've observed. I have to say, my girlfriend kind of likes the car more than before because of this so I think it is, in and of itself, a big plus over the stock setup

What's next ?

Up next, I'm continuing to put miles on the engine. Once my daily will be back from the body repair shop, I'll be putting the RX-8 on the dyno, and getting it properly tuned. Really looking forward to posting more updates, as well as videos of the engine running and such !

Cheers

Larry

Last edited by laurier.lg; 09-29-2023 at 10:04 PM. Reason: Add attachments & edit wording

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