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SCCA Street Modified RX-8

Old 03-20-2019, 11:48 AM
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This is awesome very inspirational. wish I had the talent and funds to do something like this. Good luck with finalizing your build Iíll be on the look out
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Old 03-21-2019, 03:20 PM
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John, would a mount like the old Eibach R2 mount be SM legal?



RX8 Eibach R2 Rear Mount
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Old 03-22-2019, 02:17 PM
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Looks legal to me.



Originally Posted by MilesJ View Post
John, would a mount like the old Eibach R2 mount be SM legal?



RX8 Eibach R2 Rear Mount
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Old 03-25-2019, 12:10 PM
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Originally Posted by SportRotary View Post
I have an upper spring perch design for a 2.5" spring that is just like the one from trackjunkie's build thread (plate that welds onto the tophat). I reverse engineered the shape of the tophat and 3D printed iterations with different 2.5" hole locations until the shock was centered for the full range of travel. PM me if you want the DXF file or more details. I had mine CNC plasma cut from 1/8" steel and it was pretty cheap.
Just following up, I had SportRotary's plates made by his buddy, he delivered them to me a day after I ordered (!) and I installed them this weekend. Simple install, cut the spring perch "tube" flush with the outer perimeter, clean it all up with a wire wheel, then weld.

I added a short piece of exhaust tubing to center the spring, welded it on, and everything seems fine. I gained a little height adjustability, and have a more robust spring perch than before. I'll get some pictures at some point but right now I'm thrashing to get the car ready for dyno tuning this weekend, installing a higher flow fuel pump in the S2 housing and doing some other minor things.

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Old 03-27-2019, 05:50 AM
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I put a proper fuel pump in it last night. And mounted the wing. The upper element supports still need to go on but that's the last piece.

A Deatschwerks 9-307-1009 DW300 fuel pump fits perfectly in the stock RX-8 Series 2 fuel pump housing. And flows enough fuel to feed the car with E85 for more than the power I expect to make, even if I run silly boost levels. Stranoparts to the rescue when I forgot until a couple days ago that I needed a new fuel pump.



I spent a couple hours on Sunday measuring up the trunk lid to mount the wing uprights. Then drilled it today. It still needs to be set up, and I haven't attached the upper element supports, but I did all the major work mounting it up. Thanks to Rick at Ciro racing for a great deal on the wing.



I bought a set of LS2 coils off eBay a couple weeks ago. I'm a little worried about the stock ignition system, as the Miata guys report having a lot of misfires with the stock coils. I picked up a set of Brisk silver plugs that should help, versus the wide-gap iridiums that were in this motor, but I won't have time to do the LS setup before going to see Pete on Saturday morning. I may bring the coils down there and if we see crazy breakup at high RPM I can always go to Autozone and get a cheap set of plug wires for a Tahoe and wire up the coils real quick.

The only other thing I did was spend a couple hours Sunday doing a nut and bolt on the car. Driveshaft, axles, suspension, subframes, diff mounts, trans mounts, etc. I don't want anything coming apart on the dyno.
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Old 03-28-2019, 03:40 AM
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John, talking about the Brisk spark plugs, there is only one part number on their site but ou plugs are of different length for leading and trailing.
What are the numbers you bought and what is your experience with theses in a Renesis engine on a race track ?
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Old 03-28-2019, 06:51 AM
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I have no experience with these coils in a Renesis, since my car doesn't have a Renesis.
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Old 04-01-2019, 07:09 AM
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Peter (PFTuning) and I had a good dyno session on Saturday. Surprisingly few issues. One oil leak due to my own dumbassery. I built a custom dipstick tube using a hacked-up tube from a Ford Ranger. I forgot to bolt the bracket down to the engine block so the dipstick tube vibrated out of the block a bit and sprayed oil on the turbo due to windage. Hence the smoke in the video below, which was our first pull.

https://youtu.be/qLjZ7kc9Mwo I've got too stiff of a wastegate spring in it. I didn't think about it when I installed the Turbosmart actuator several months ago, and it comes out of the box with a 14psi spring. Too stiff to be able to ramp boost up gradually with RPM and throttle position, and to do traction control as well. So that's got to come out. the other problem we had was ignition breakup above 6,500 RPM. I'd like to turn this motor to 7,200 occasionally (higher once I build a really stout engine for it) but the ignition breakup was too bad so we got out of it. The plug gap was right on, but the stock MZR coils are not great. I'm picking up a set of 370Z coils or something else that is known to be strong.

Bottom line, it made 402hp at 6,500 and was climbing. We only had about 15psi of boost in it. Torque peak was 390 before we trimmed it down with some retard on the intake cam. Final numbers are it makes more than 330ft-lbs from 3,500 RPM up to 6,500, with a peak of 370ft-lbs at the wheels on a dynojet. My old BMW made 240-245hp on this dyno and around 236-240ft-lbs torque on this dyno.

Gearing is set up to do 74MPH at 7,200 RPM, but the powerband is so flat (the torque curve is like a tabletop) I think it will be very driveable once I get the boost ramping up smoothly.

First local event in two weeks... pretty excited.
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Old 04-01-2019, 11:57 PM
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Looks like a shedload of nice work.

The 2.3 here uses 35 gtr cop to get rid of the unwieldy coil pack at the back of those engines. Was thinking of the cosworth stuff, but it's undoubtedly just an oem coil rebranded - and up-priced! Bit wary of the LS gear with all the fake GM stuff on ebay and the 370 coils will probably be as good. Wasn't too much different price wise, nissan genuine new v LS new either.....at least over here.

Going by the output, what's the turbo, 6758 or 7163? Have an ex Indy hairdryer on the car here, couple hundred bucks - and I couldn't refuse - more work making an intake snout and the unique v-band turbine inlet on the downside.

Having broken engine mounts in the past from torque reaction, I might look for a bit of a strengthening web on those tube mounts though, if there's any room.
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Old 04-02-2019, 05:48 AM
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Originally Posted by billyboy View Post
Looks like a shedload of nice work.

The 2.3 here uses 35 gtr cop to get rid of the unwieldy coil pack at the back of those engines. Was thinking of the cosworth stuff, but it's undoubtedly just an oem coil rebranded - and up-priced! Bit wary of the LS gear with all the fake GM stuff on ebay and the 370 coils will probably be as good. Wasn't too much different price wise, nissan genuine new v LS new either.....at least over here.

Going by the output, what's the turbo, 6758 or 7163? Have an ex Indy hairdryer on the car here, couple hundred bucks - and I couldn't refuse - more work making an intake snout and the unique v-band turbine inlet on the downside.

Having broken engine mounts in the past from torque reaction, I might look for a bit of a strengthening web on those tube mounts though, if there's any room.
Thanks, it's been a long journey.

A friend dropped off a couple of sets of coils, some R35 GTR and some 370Z, and it looks like I can make something work.

Turbo is a 7163 single scroll, V-band turbine inlet and outlet. Nice and compact.

The engine mount brackets are going to get redone at some point. I made them this way originally so I could use factory MX-5 engine mounts. Next winter my plan is to yank out this engine (Assuming it survives the season) and build something with stronger internals so it can tolerate more revs. At which point I'll rework the tubular subframe to allow a more conventional engine mount. The challenge is on the left front corner there is almost no room due to oil cooler plumbing, the oil filter, the steering shaft, etc so it's going to have to be built around all that stuff.
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Old 04-14-2019, 07:12 PM
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It runs, it's fast, and it's really fun. There is a ton more work to go still in terms of sorting both in power delivery and handling. This is new territory for me, coming from the BMW, so I'm well behind where the top RX-8 is in DSP but I'm looking forward to getting my car handling that well.

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Old 04-15-2019, 02:13 AM
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Oh man, I have that exact turbo sitting unused at my house. Would have loved to have unloaded it.

It’s awesome you have your car out there already. Looking so forward to you developing it fully.
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Old 04-15-2019, 11:40 AM
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Thanks Mark, I anticipate it being a very long road. I only have one practice / test and tune event before the first Pro, where I will quickly learn just how much more development I have to do. If I had just gone FI with the BMW I think I'd be in better shape because I understand that chassis better. I'm kind of starting from scratch here and there isn't much public information on the RX-8 as far as what spring rates and ride heights are a good starting point. So I've done the usual spreadsheet work and picked some stuff, but feel like it's going to take a long time to get to a decent setup. Then again the RX-8 chassis is so good compared to the BMW it's probably harder to screw it up.
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Old 05-01-2019, 04:17 AM
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Wow, that first autox vid really got me pumped up and excited. What a beast that will be once you get it dialed in.
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Old 05-01-2019, 06:09 AM
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Thanks Mark. It's a lot of fun and I'm looking forward to getting it dialed in.

I cancelled out of the NJ Pro this weekend. I've got a bunch of little problems I couldn't get resolved in time. Kills me, because I really enjoy the NJ Pro, even though my old car broke pretty much every year I took it there I'm signed up for Spring Nats which is less than a month away... that should be enough time to get everything resolved and get another local shake-down event completed.

The big thing is cooling. I finally picked up a radiator capable of cooling the thing, and then discovered that my electric fan only worked on its "medium" speed setting. I don't think there is any way it's surviving multiple runs at a pro unless the fan can extract all the heat. The new rad has about three times the water capacity of the stock miata junk, and I'm working up ducting between the intercooler and the rad, so I think I'll be OK.

I like the RX-8 so much better with this engine than with the Renesis. IMO it's how the car should have come from the factory.
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