Hello fellow racers. My name is Sam Harris. I've been racing for 11 yrs in everything from BMWs to Miatas to Porsches to Hondas. I noticed that RX-8s swept PTD at Nationals this year but no one is running an RX-8 in TTD. I've instructed people with RX-8s and driven a few on the street but never owned one. They seem to handle like a mid-engined car... easy to rotate (which I love).

Anyway, I've been thinking about fielding an RX-8 in NASA TTD this season. I've tried searching these forums, but the search feature doesn't allow searching for multiple terms. It just seems to be equipped to "or" not "and" all parameters. This makes it exceedingly difficult to find threads like, "Year to avoid" or "Common problems with tracking." Every car has its quirks... Porsches blow power steering pumps if you don't insulate the return line. Every car has its secrets... Miatas are faster with narrower tires because the decreased rolling resistance more than makes up for loss in lateral traction. There are a thousand little tidbits that you only know if you've logged the laps.

I was hoping that you guys could point me in the direction of some memorable threads where these kinds of lessons can be learned the easy way. I haven't yet bought my RX-8, so everything from what years to avoid, what things to look for, how to shave the most weight, how to avoid burning seals, how much tire you can cram in the wheel wells (and if it makes the car any faster on a track), what shocks, spring rates, and sway bars do you prefer, how much toe and why (I did read the "post your camber settings" thread). Thank you in advance!

Genuinely,
Sam Harris

 

First welcome to the forum! second thing, I humbly am replying to your post because I am not an authority. All I know is what I've heard from club members who are seriously into racing on the track. I don't mind telling you who they are, because I have high respect for them, however - I will need to ask them first (courtesy).

The first thing I've heard from both of them:

Chassis:
Serious gains through stiffened suspension, large diameter sway bars, 4 point tower bar, and other tweaks to the chassis to make it more rigid. Also, the RX8 is blessed with large wheel wells, and you can probably fit up to 295 tires in front and back. The wheels and stiffened suspension make a whole dimension of change with this car. With light weight alloy wheels, you can have the best of both worlds. IMHO (This is humble opinion): The RX8 has greater aptitude for cornering gains, less aptitude over Horse Power gains. If you want a noticeably faster accelerating car, you're left with getting a good turbo/super. (I say this for other members on this thread)

Brakes:
Some how the RX8 takes to braking very well. With performance brakes (brembo brakes), you will probably notice shocking stopping power.

Draw backs:
This is second hand, and I don't want to steal anyone's thunder (because this is their remarks and not mine). The fuel pump and fuel lines have a quirk that is only noticeable when you are doing over 1g in the corners, it can be catastrophic if you are not prepared. What is it? This:

The rotary engine can use so much fuel, that during a 1g+ long left turn the fuel pump will run out of fuel because the fuel is being pulled away from the fuel lines (under the rear drivers seat) where it connects to the gas tank. This is more noticeable if you have a high powered performance fuel pump. From what I've heard, the way to fix this, is to have a second fuel pump (one you can switch off [motor burnout]) on the opposite side (right side) of the fuel tank, mounted under the rear passenger seat. (Basically you have a fuel pump under each rear seat). This made a difference for my good friend.

I encourage you to ask around about the items above, just to make sure I'm not full of it. I am only commenting from the experience of two other people, who independently have track experience.

I hope this helps out friend!
I've seen some pretty awesome RX8s on the track... there is so much hidden potential in these cars!!

Enjoy!

 

Gyro Bot, couple of things...

---with too big tires, you lose top end and acceleration. I've found 255mm a good compromise.

---just get some good pads and the brakes are fine even under racing conditions.

---the fuel cutout only occurs when you are 1/4 tank and below, regardless of lateral G force

sam_h if you are frustrated with the stupid forum search....just pull up Google and use a command in the search like this:

rx8club.com: Common problems with tracking

or

rx8club.com: Year to avoid

 

I wish

 

sam,

i would send a pm to trackaddict..

he runs tt in nasa in the ga area..

beers

 

I've missed where else you get cut out. I got fuel cutout at nelson's ledges this weekend under 1/4 a tank coming out of the big sweeping rh carousel. Put my pedal down for the straight and nothing happened. But I've never heard of people having cutout on 'gentle' turns or straights. I thought I've seen most of those discussions but I know you've experienced most of the issues people have on the track.

For OP there aren't any real things to stay away from. Our chassis hasn't changed and there hasn't been any noticeable changes to the car until '09 and most of that is just bringing the stock version up to what good aftermarket parts get the 04's-08s. Avoid anything with a sunroof, but you probably would anyway, and base models w/o options tend to be the easiest routes. Your biggest concern with a used model is going to be the engine. Until the most recent flash in Nov '07 the engine management simply wasn't managing the engine wear well enough. People who maintained their cars were for the most part OK but most owners were probably putting entirely too much strain on the engine. If you can find a base 04, 05 that has had its engine replaced in the past year that might be your best bet. Make sure you get a compression check before buying anything that hasn't had an engine replacement if you plan on racing it.

The brakes on this car are fantastic. Put on a good set of track pads and you're good to go. Beyond that I'll defer to the guys on race teams but really the car was designed to be tracked from the bottom up. Too bad they ever built it with an autotragic.

 

+1

Fuel cutoff happens because we have a saddle tank that straddles the driveshaft so hard lefthand sweepers will slosh fuel to the right side and if it's long enough the fuel pump will starve. It's a combination of lateral load+time-fuel tank level=cough/misfire.

 

Gyro bot,

Thanks for all the ideas. In the TTD class I won't be able to make quite that many mods. Swaybars (2pts), Coilovers (5pts), and 255 V710s or Hoosiers (11pts) would only leave me 1 pt to spend (and a chassis brace with more than one connection point costs 2pts). Would it be worth running 245s (-1pt) to spend on a chassis brace? A rear lower chassis brace on a Cayman or Boxster adds about .4 sec a lap belive it or not, so you never know. Brake pads and good fluid are free, as are any wheels. Are the stock wheels light enough? I can pull anything out of the car I want so long as I cross the finish line above 3045lbs (with driver). There are no points for fuel pump alone if using OEM fuel and timing maps, sensor inputs and ignition timing.

Thank you and thank you!

Swoope, I instructed quite a few RX-8 guys at Road Atlanta back in 2004-2005. One of my students was there for his first track day and we went to Sonic for lunch. I hear through the grapevine that he's quite the time trial racer these days.




EDIT: I can't find any mention of fuel cells costing points in the 2008 TT rule book. Would that solve the fuel starvation problem?

 

Where and how has this occurred over 1/4 tank for you? I'm pulling 1.45Gs regularly on track and haven't found it a problem. Perhaps you have fuel pump failing?

 

Are you talking about sustained 1.45gs such as a long sweeper or high G's in quick chicanes? I've found it has a lot to do with time at high lateral loads. The longer the hard corner the more time there is for the pump to go without fuel and you see starvation. If it's just quick back and forth it doesn't seem to be a problem.

For example I saw fuel starvation on Pacific Raceway's turn #2 but not 3b. I believe mainly due to the sustained Gs on Turn 2 vs. 3b.

http://www.pacificraceways.com/road/roadcourse.cfm?

 

It's any sweepers - not just left or right. If either tank is low because the fuel has sloshed onto the other side you'll get the cutout.

They're relatively light (~23lbs) but for competitive racing they should be replaced.

There's a good thread on building two 8s for the Koni challenge series here:

https://www.rx8club.com/rx-8-racing-25/new-endurance-racer-build-137330/

 

There was a TV show linked on Youtube (I think) that had Speedsource letting someone in Japan drive in the Koni challenge. The drive started to get the fuel starvation issue and the Speedsource engineer told him that it's a common problem and the Koni drivers have learned that it is extremely important that they drive very smooth in any series of turns if they want to avoid the starvation so it doesn't sound like it's just the big swooping turns. It sounds like as the fuel level goes down it can occur on any turn if the driver isn't being extra-smooth.

I'll try to dig up the link.

 

Good info. I think we're in violent agreement on this.

There is a fuel starvation issue that needs to be addressed by either creating a new fuel cell (may be a requirement anyway) or setting up a new fuel pump.

 

Speedsource sells a new fuel tank (for track use only) that is suppose to take care of the problem. I don't know what mod they make to correct this. It is pricey.

 

Ah. Here we go.

http://videos.streetfire.net/video/B...-22_194195.htm

The race starts at 16:00 and he starts having fuel issues around 22:00. The Speedsource rep is talking around 24:30 about the fuel starvation issue. Just says they try to be very smooth in that car.

 

I'd say that on average I'm experiencing 1G or a bit more on sweepers I'm familar with. I try to ratchet up my speed to use the available grip I have (with a bit to spare for personal safety esp at higher speed) and that's typically where I'm at in those situations. Use the track map links below and follow along for some examples.


Mt Tremblant ...starting w/turns 1-2-3-4, going from ~100mph in a downhill right-hander at 1 that climbs perhaps 75ft to 2 at the top of the hill where you must be accelerating to avoid a nasty spinout over the top which drops off very quickly (fun!!) on the way down to 50-60mph at 4; then 5-7 a high speed run in the ~90-100 mph thru 6 decreasing to ~80 before starting into in 7. Turn 7 is one of the most dangerous places on the circuit as it's off-camber and you have to accelerate thru it pretty much full throttle or risk spinning.

http://www.lecircuit.com/circuitDocu...Eng1%20(2).pdf

http://www.lecircuit.com/circuitDocu...MT%20areal.jpg

Calabogie ... esp. 'The Ridge' continuing to 'The Spoon' and 'Left' Quoting, "The Spoon is a long concave turn to the right along which cars will carry maximum speed while constantly turning and dropping down to the apex.." This one is really fun as you are like in a long downward right hander but in a sluice where acceleration feels oh so right!

But also check the descriptions of other curves out there are plenty of high speed extended turns.

http://www.calabogiemotorsports.com/...23/41/lang,en/

It's very puzzling why you guys experience that and I (perhaps others?) don't under other than ~1/4 full tanks. I don't know why these conditions wouldn't give this starve-out, but I do know it only occurs with my car near or at 1/4 tank. Strange to say the least. Perhaps I'm just so smooth I'd still suggest checking you fuel filter (OD had problems with sludge on his), or your pump pressure.

 

For what its worth I have a post going on regarding my first HPDE in my Mazda (not my first HPDE) and I mentioned that when I got below 1/4 tank my RX8 was cutting out about 3/4 the way down the long straights at Sebring.
https://www.rx8club.com/rx-8-racing-25/sebring-my-new-rx-8-a-158088/
It never happened in the sweepers just on the straights. At the time it seemed like fuel cutout to me but I was puzzled because I had a quarter tank on the gage. It never happened again after I got suspicious and kept the tank above half full.

 

It was doing it in long sustained left sweepers...like 5 sec over 1G. It did it with a brand new fuel pump NA...and with an upgraded higher flow pump with the turbo.

Did a bunch of mods...and haven't tested it yet...but it should be good now...2 pumps with the return going back into the cup to keep it full

 

HEHE, you figured out the secret that soo many of us race teams have been playing with for a little bit now. Believe me, it'll work well!

 

It had better...or else I'm getting out the torch

 

Just to pass along, we still get a bit of fuel starvation once we fall below 3 gallons. Figured out there is no way around it...always up for new ideas on the matter though.

 

Dry sump fuel tank? collapsible bladder?

 

Good ideas, but we are limited by Grand-Am rules...dry sump=not stock, collapsible bladder=not stock...

 

Are there any RX8 race shops closer than 6 hours to me (DC metro)?

ROAR: Troutman, NC (379mi)
BERG: Rochester, NY (383mi)
SpeedSource: Sunrise, FL (1019mi)

Thanks,
Sam

 

Sam, I don't know of any other shops near you. Especially one with a Grand-Am ST program...that would help you out the most.