justjim

I tried out my, new to me, 2007 RX-8 at a Chin Motorsports HPDE event this past weekend at Sebring. I've been a regular there previously in my Acura RSX-S. I really liked my Acura but the Mazda gives me a woodie at the track.

I spent the first 2 sessions feeling out the car on street tires then switched to Hankooks in the afternoon. Love the way the car handles compared to the Acura. Balance, and RWD, woohoo. I put Cobalt track pads on for the event and the brakes were awesome, not a bit of fade. My best time in the Acura was a 2:48. My best time the first day in the Mazda was a 2:44. I think I can drop that another couple of seconds when I learn to take better advantage of the superior brakes and my new seat comes in.

One question for the forum. The only issue I had, which I think I resolved, was a the engine cutting out at high speeds on the straights. This wasn't happening in the corners, but happened around 100mph about 3/4 the way down the straights. I noticed, and I think this is the clue, that it happened when the gas gage was reading about 1/4 tank. I initially thought, "can't be starving I've got a quarter tank". But after this happend about 5 times over the weekend I went to get gas and I put 14.5 gallons in a tank that said 1/4 full when I left the track to go get gas. My theory is that the gas gage sucks and I was nearly empty. I bought an extra jerry can of gas and it never happend again. Any other ideas or thoughts. The car always ran great except for these incidents where it felt like someone had reached over and turned the key off.

Matt RX8

congrats on the purchase. The phenomenom with the fuel cutting out is quite common. For me, it usually happens on the straight after I've come out of a sweeping corner (usually a right hander). I try to make sure that I start each session with at least a 1/2 tank of gas and since I've had no other issues.

justjim

Well that's what I seemed to have learned too. What's up with our squirrelly gas tank then? Is there something unique about our RX8 gas tank that requires a half tank to do its business? I could go below an eighth in the Acura and then it would only be a problem in corners.

SouthFL

Keep it over a 1/4. I have experienced similar fuel issues at Sebring in the 8.

olddragger

iTrader: (3)

has dual tanks that relies on a siphon action from the opposite tank from the fuel pump in order to balance the amount of fuel in the both tanks. when it gets low gas goes to the centrifigal force side and the pump cant keep up. No baffling etc can help. You have to see the inside of the tank to understand.
Speedsource can fix it for a price--but since I am not trying to squeeze that much out of her i keep it well over 1/4 tank at all times on the track.
Most of the time i keep it at 1/2 just to be sure. The engine dying while you are under full throttle exiting a corner is not good when someone is on your tail!
OD

RK

iTrader: (1)

Does it matter whether its a left or right sweeper before the straight or does it start to cut out on any of them? I was running at close to 1/8 of a tank and was still hitting 125 at the end of both days without any hiccups but I know Sebring has three +100 straights and much bigger sweepers.

Might be heading down there in January so that's good info to know.

justjim

Well all three of the long straights at Sebring come after right turns and I had the problem at one time or another on all three straights. It always happened toward the end of the straight when I was hitting 100+mph, so I'm not sure if its related to the prior turns which were quite a bit before the incidents.

SouthFL

My coolant and oil lights come on as well at Sebring (thanks to Turns 1 and 17). They're always topped off when I check them at the end of the session and usually, the lights turn off while driving the northern part of the course.
I've also gotten a CEL or two as well since running with a catback. CEL clears at the end of the session.

I bet you found your turn-in points much sooner than expected with the RX8, eh? T10, T13 and T15 have rather early turn in points where the RX8 simply doesn't run out of room at track out, despite what your gut would tell you.

justjim

Well that explains alot, when I was changing the brake pads I thought I noticed that the gas tank was kind of split but wasn't exactly sure. I wondered if that might be responsible and you have cleared it up for me, thanks. I'll just keep it above 1/2 tank in the future. I'll be bringing more gas cans.

You're right its uncomfortable when I see a open cockpit full race car coming into my rear view just as my RX8 decides to take a nap.

olddragger

iTrader: (3)

Glad to help a little. Fuel pumps are a one piece assembly (regulator/small sump area, filter etc) and relatively inexpensive and easy to swap out. If you regularly track your car you will end up replacing it every yr or 2.
OD

kjullion

I'm hoping to attend my first HPDE event at Homestead in Dec...these tips will be excellent reference points in the event that I encounter the same.

justjim, bummed that I missed out on seeing an 8 on the track at Sebring last weekend. I was there on the Saturday, getting a passenger ride...that was HPDE2....in a BMW 335i (monster amounts of torque and surprisingly good in the corners) which made for a pretty awesome day, only 1 Mazda do I recall and that was a Speed6.

justjim

Sorry I missed ya. I was there in a dark blue RX8. I ran in the advanced group 2 and ran every session. Maybe I was too fast to be seen Who were you riding with, maybe I've met them?

takahashi

It may be fuel starvation but you don't have a speed limiter in a JDM car don't you? ??? ^_^"

Coz 100mph is awfully close to the speed limiter of 180kmh.

Just kidding... most US cars won't have it.

Also if it is only hesitating at high rev of 3rd or 4th gear. It is also time to look at the spark plugs.

swoope

iTrader: (5)

it is a combo of things in the usa.. from what i have learned...

left hand turn fuel cut.. premix not done smart... coils.. plugs not likely...

to the op.. really, if you get below .25 tank with out an issue you are doing well.. i can cause a missfire in a straight line with less than a .25 tank..

denny, going to have a silly mod for nov 8..

beers

Senna

I've experienced it too when on the track with about a quarter tank. Now I just make sure it's at half or more and it's never happened since. Unfortunately a good hot lap on light fuel load doesn't fly in this car. Nevertheless, I'm having a blast running with the big dogs. Did get passed by a GTR and 430 this weekend at Buttonwillow though. Kinda made me chuckle.

takahashi

Interesting swoope, we have lots of coil issues down under. Personally I am ok.

Senna, perfect example of you can buy good machine but not good drivers.

Matt RX8

Did you ever check the CELs? Was it the misfire at plug #2? Which cat back are you running?

I have a misfire CEL that only happens on the track. Recently replaced plugs, coil and plug wires and still happens. For next season, I'm going back to the stock exhaust and see if that helps. I'm running the Greddy SP-2 right now. My car also shoots flames with the SP-2 but only on the track. Never did that with the stock exhaust.

SouthFL

^

Sorry, didn't scan the CEL.
I've run CEL free with my custom exhaust for a year (single exit through a Magnaflow round- picture HKS Hi Power) at track days.
Now, got the CEL with a Turbo XS catback.
Stock midpipe on both setups. I've been told that the custom exhaust produced much flame.

Kafka

Mazdaspeed exhaust gives me flame on the track, and a little bit less than 1/4 fuel will start having fuel strav for me...

bugster

so which one is fastest on a straight line?
RSX-S or RX-8

i was considering them both before buying the 8

costello

I've realized now that the gas gauge isn't that accurate during track events after about 1/2 tank. It will show 1/4 or 1/3 tank and when I leave Sebring to go get gas, it drops like a rock and the light comes on. When I fill up it was ~14 gallons. The gas station is only about 2 miles from the track too. Now I just go fill up when it's at 1/2 tank.

justjim

I was hitting about 112 mph on the back straight with the RSX-S. I was hitting about 116mph on the back straight with the Mazda RX8. My impression on the street and on the track is that the Mazda is a little bit faster in a straight line but not a lot than the Acura. Some of it is the hp increase, 231 vs 200, some of it is that the rotary revs faster I think do to less rotating mass, and some of it is that I'm coming off the turns faster because the Mazda definitely out handles the Acura. My Acura had OEM springs, Koni shocks and Eibach sway bars and an out of spec alignment. My Mazda is bone stock except for the alignment. If your still looking for a RSX-S I have one for sale

justjim

That was exactly my experience.

kjullion

justjim,
I was with the guy in the 335i white, with the blue "16" but we only hung out on the Saturday. Another guy we know there was running the with Radical...which is pretty sweet! I think he did the Saturday and Sunday at the last event.

I'm going to revisit the link with the pics and try to find you now that I know which group you were in. So what kind of laptimes are you getting at Sebring if you are in Advanced Group 2?

Cheers!!!

justjim

I don't think I'm in any of the posted pictures, they don't show every car just a sample of the photographer's pics. I need to go to the photographer's website and buy a few pics of my car.

I know a guy named Eric that used to run a Jeep SRT8 and now has a BMW, was that him by any chance? I was turning 2:45 and 2:46s consistently by Sunday. I had one 2:44 (and change). I think I can get another second or two with more time in the car. Also the car is bone stock except for tires and brake pads. With time I may get some Konis and a set of sway bars. I've ordered a Corbeaux FX1 seat but the mounting sliding brackets are taking forever. Hopefully a better seat with keep me tucked in one place so I can concentrate on lowering my future lap times. I'm still trying to decide whether to do Sebring again in Dec. The economy is making me nervous.