JakeKaminskisRacing

Well if you're looking for a race car then reliability isn't an issue with the Renesis. They only have issues with reliability on the street for daily use because the engine doesn't get hot enough for complete combustion and carbon builds up. On the track this doesn't happen, the engine gets hot enough that it burns off all the carbon.

Rebuild a low comp engine and you're good to go. They don't make a ton of power, but they don't need to. RX8s have been dominating SCCA STL and the 25hr of Thunderhill in the past years! Keep the momentum going and it's fast! And the stock brakes are quite sufficient just needs pads and lines with good fluid in them and good to go!

I'd say avoid the K swap unless you're dry sumping it. The longitunial mounted ones aren't a fan of G forces and spin the bearings. My buddy is on his 4th engine in his miata race car.

trackjunkie

thanks for your input on the renesis engine for track use and the k series. what about the sr20 swap. has these been a proven swap for the rx8 chassis?

JakeKaminskisRacing

I have seen a few SR20DET swapped RX8s on the web, although I haven't driven one in an RX8. I have driven an SR20DET swapped NA Miata. I think it'd prove to be a good engine for our chassis, even in stock form.

I had considered putting one in my second RX8, but I may have a good deal on another RENESIS. If that deal falls through, then I may pull the trigger on another engine.

TeamRX8

iTrader: (25)

If true, it seems odd that there wasn’t a single RX8 listed in the STL results at the SCCA National Runoffs Championship last month for a 56 car field

Adax

iTrader: (2)

One was dominant for the first 2 -3 years of the class (Ray huffmaster). It was apparent that the car was an over-dog and it was saddled with weight increases (2870) and restrictor plate (45 mm) until it was no longer competitive so none have been entered since.

I've successfully lobbied to get weight and plate out of the car and plan to make a run in the next couple of years after some development. Currently we need to get the FWD weight reduction removed since it is apparent from this year's results that FWD has no problem competing in this class (top 4 were engine swapped civics I believe). If you are an SCCA member, I'd appreciate you letting the CRB know that the time of giving FWD cars a weight reduction has passed. STL is becoming a FWD class which was not the intention.

https://www.crbscca.com/

Mr. Pockets

Sadly, this is not the case. Track use does not cure what ails the Renesis. Not even close. Because of the location of the exhaust ports, among other factors, the engine gets super hot, and those repeated heat cycles cause the side seals and springs to get heat treated. They cause a loss of compression and you're done.

Track use also results in more time at high engine speeds, which causes chattering on the housings.

Ask Eric Meyer, who says he 'stopped counting at sixty new engines' within a few seasons of racing three cars professionally. It's seriously the worst engine ever. Super fun and I love it, but objectively terrible.

TeamRX8

iTrader: (25)

No offense to Eric, but there are plenty of racer experiences/results that differ from his own

TeamRX8

iTrader: (25)

Well the response below is quite counter to the previous assertion. So thanks for clearing up that it’s not currently competitive in STL and whether it ever will be again is in question.

JakeKaminskisRacing

I fully agree with you on that. Seems the CRX with a B20 is the current ticket in STL, Sam Meyers loaned his car out for the Runoffs and they took the podium in Indy.

The hp/weight balancing act needs some work for the class. Maybe one of these years I'll attempt SCCA STL, however I'd rather stick with NASA Honda Challenge for now. I have a new car to put to the test. Just want to make plans for my other RX8 down the road.

Mr. Pockets

That's fair. But if anybody has repeatable methods for getting longevity out of these things, and can back that up with more than anecdotes, I would love to hear about them.

I just don't agree with Jake's claim that the Renesis's reputation for failure isn't an issue on the track.

TeamRX8

iTrader: (25)

Well the Mazda Pro guys were getting multiple seasons using the same builder that he was at one time, he then went on to build his own or have them built locally. He also swore using premix was Renesis death despite all the other racers who don’t have any problem.

I don’t necessarilly agree with that comment either, but some people have more/less issues than others.

R(ace)X-8

Wow, talk about being out of the loop on your own thread.

Well, let's see. Couple updates, couple comments:

RX-8 as a Track Car

I haven't had a reliable car. I'm on engine #3 w/in a 12-month period. Overwhelmingly, I'd say the bulk of this is due to the previous owner's ridiculous build/maintenance practices (engine #1 came with the car, and it was pretty much junk). So I don't feel "OMG" is entirely in order for the platform. Yet.

My engine builder has done work for folks who've had multi-year success running the engine w/o trouble - and then my engine from him (engine #2) dropped compression after 2 events. He rebuilt it, we found another "WTF Kevin?" on the car, mapped out an extended break-in, and so far so good.

I agree with Mr. Pockets that the engine is finicky (Ok, full-disclosure, I have a love/hate relationship with this engine). I use premix, watch oil level religiously, have oversized oil coolers, etc., etc. On track it puts out a ton of heat, and that plays havoc with OEM seals, etc. An occasional blast of RPM on the street may help with carbon build up, but extended track-duty puts you in a whole different world of heat management. Given the architecture of the engine, the water jackets only circulate on the outside of the engine - so water temps are never a problem. The oil-system IS the cooling system for the engine internals (that's why you have oil-jets squirting the inside of the rotors). Nothing really has a decent way to get at and thus cool those side-seals, so you do what you can by keeping the oil temps under control.

With the exception of cleaning up the p.o.'s stupid stuff, the rest of the car has been great. I mean, off-the-charts fantastic. It's a hell of a fun car to drive. And it's serving rather well at meeting one of the goals I had for it: teach me how to drive a momentum car. I'm loving that part of it.

Class Competition

Well, currently I'm not making as much power as I thought. I think my builder's dyno is optimistic. Ahem.

Subsequent chassis dyno runs have me planning to drop down a class, since the car's a better fit for that power-to-weight category. So this thread will end, and I'll start up another one for the TT5/ST5 Build. I'm assuming that TTC will convert to TT5 in 2018, but it'll be the same build even if it doesn't.

Build Updates

Dealing with gremlins and such took up most of the season. The last month I've been OBSESSIVELY working on Halloween costumes for my son and I.

So the car still looks like this (sitting on 285 Pirelli scrubs):


Chillin' in the Autobahn Country Club paddock



In the off-season, the plan is this:

• New doors go on
• Dents/dings smoothed
• Hood vents fabricated (yeah baby!)
• Front undertray extended (never happened this year as originally planned)
• Vinyl wrapped w/new color scheme (wish me luck Nick, this is another one of my "never tried this, don't really know what I'm doing" bits)
• Muffler orientation moved to a center-exit

Other than that, standard maintenance items, incl:

• New front wheel hubs
• All fluids changed (oil, water, brakes, trans, diff)
• Alignment

Any additional suggestions on stuff I should address during the off-season, please feel free to pass it along.

See ya'll in the new thread once the sparks start flying on the TT5/ST5 build!

Best,
-j

TeamRX8

iTrader: (25)

That’s ok, we can talk poop in your thread without needing your participation

trackjunkie

what rear diff cooler setup do you have?

R(ace)X-8

Actually none. The p.o. had thought to put one in when the car was built, so he had the diff plumbed for one. However, there's just a loop of braided hose in place right now.

I have a couple of Setrab coolers that I thought I might use...or a couple of heat exchangers from Pettit that came with the car (from their oil-cooler kit). I just need to get the pump in place, wire it, and then figure out what the inlet and exit should look like (I'm not a fan of just sticking heat exchangers in a trunk and letting the air stay stagnant and heat up, that's just lazy engineering).

Of course, I need to get to other things and decide how much more effort I'm willing to put into this thing.

trackjunkie

yeah i saw the picture had fitting in the diff, so i thought it might have rear diff cooler. I just wanted to get an idea of cooler size and pump to use if i was to do one. or just get a larger diff cover. i didn't really see much options out there for after market diff cover. i see that Greddy makes a diff cover for RX7 FD, would that fit RX8 since i saw some post of people swapping rx8 diff cover to rx7 for larger cooling fins.

https://www.rx7club.com/3rd-generati...-cover-997318/

R(ace)X-8

Don't really know about cover interchangeability across the RX7 and RX8 platforms. Looks like they do.

I don’t have data on the diff temps. So I don’t really have any accurate way to tell what size cooler one should use (if "should" means something like "optimal efficiency") – and anyone who does say they can tell without data is selling you something or speaking loosely about anecdotal evidence they’ve collected. Heat exchangers are not rocket science, but there is a pretty clear science behind them as well as a well-worn engineering path to follow with the proper data.

So without data, here’s how I think of it – if you fear your current cover is not up to snuff, just go with a cooler set up. Sure, larger fins are better, but if the objective is to really provide an insurance policy to deal with large amounts of heat, just go with the cooler.

If you look at most kits that are developed by race teams, they’re not using a massive heat exchanger. Most are round about an 8” x 8” area. The install is more important than the exact size of the exchanger. These things don’t work by magic, they work by airflow. So you need a way to get the air in and a way out. One of my pet-peeves is to see exchangers just stuck somewhere with no thought to how air will pass over the fins. If you want to get moderately “fancy” you duct the thing with at least some thought given to the pressure differential ahead of and behind the exchanger. Fans are just a way to "cheat" when there's no ambient flow to tap into. Again, none of this is rocket science, but there is a science behind it.

The pump often used in this application is pretty common, something like a Tilton fluid pump. Tilton doesn’t manufacture these, they just put their label on them. So you’re probably able to source one for less and/or under different labels (Mocal, Genesis, etc.).

Best,
-j

Adax

iTrader: (2)

I don't have a lot of data yet but my dif fluid temps were up to 260 in about 3 laps. Turing the cooler on pulled it down to the 240 range within a lap. I should have more data next season.

Here's my install

https://www.rx8club.com/rx-8-racing-...1/#post4839914

(post 15 if the link doesn't work)

TeamRX8

iTrader: (25)

Ridium in NZ makes one, US importer is Rotary Performance in TX




[url ]http://www.facebook.com/ridium7/[/url]


Also Revolution in JP, can be bought through JapanParts.com, that adds about 3/4 qt capacity, you will need to add the cooler line port(s), but fairly easy due to the bottom sump extension

.


.

trackjunkie

i can find links to the ridium one.

https://www.rhdjapan.com/revolution-...over-se3p.html

cant you use the fill and drain ports for oil cooler line?

TeamRX8

iTrader: (25)

Their hatebook link is posted above. You have to copy and paste it into a browser because it won’t hot link properly here

I think you could if you use tee fittings to allow draining and adding fluid without taking the lines loose. You could at keast do that on the drain/outlet. Not sure you want to bring it back high like that and possibly cause foaming.

hufflepuff

The rx8 is looking decent under the new TT5 rules. Probably easier to be competitive there?

blackmount

Pretty awesome build thread.

The condition in which you received that car makes the racecar I bought last year look like it just rolled out of Stuttgart which is really sad since mine is just a home brew non competitive track car some older gentleman built on a tight budget.

I look forward to seeing more progress with this car - Do you ever Visit Road America or Black Hawkfarms for basic Open Track days?

R(ace)X-8

Thanks man!

Yeah, I used to go to Black Hawk at least once a year and get up to RA 3-4 times a year. Lately it's down some. I haven't been to Black Hawk since 2014 (did my comp school there...in the rain...with the CMC guys...yeesh!). I should be up to RA a couple times in 2018 with MVP Track Time. Their October event there is usually my traditional season-ender; great way to send off the track season.

Love to see you up there! Let me know before you go.

Best,
-john

R(ace)X-8

Yes, I agree – the RX-8 is a much better fit for the new ST5 class. I was going to open a new thread for this car’s (now) ST5 build. I had a couple of things to wrap up for the ST4 build (mostly cosmetic stuff), but I knew I was going to be under-powered. So that was about all I needed to switch directions once the rules came out.

Unfortunately, due to the rather harsh penalties imposed on aero, I’m going to have to lose the front splitter. You take a huge points hit for it – and that’s on top of the built-in points hit you take for a non-OEM rear wing and the ridiculously harsh hit taken for an upper A-arm style suspension. Added up, I’m “overpowered” and/or “underweight” with the resulting adjusted weight-to-power. So something has to go, and I can’t undo the upper A-arm architecture…

The plan is to keep the rear wing, add a bit of ballast (mostly w/a passenger seat, something I’ve wanted anyway for track days), and take advantage of the front air dam allowance. The current splitter frame can stay, since they allow a flat tray forward of the wheel centerline. The only thing that will come off is the front blade (the support struts can be strapped to the bumper and tucked under the fascia). For track days I can easily put the blade back on and run it, so not as much fabrication lost as it seems. The new front air dam will bolt in the same place as the splitter blade, but it’ll extend up to the leading edge of the fascia – much like the typical Miata practice seen when they use the same rules allowance.

I’m hoping the RX-8 will be competitive. Some of the sample adjusted calcs in the new rule set surprised me. I expected to face the Miatas, E36 M3s, and stock-ish S2000s, but looks like I could also face early Porsche Boxters. The real flexibility of the class was on display with their example of a built-up 2009 Hyundai Elantra w/motor swap, aftermarket brakes, etc. Should be an interesting class if folks come out to play. =)