Thanks for the input and keep it coming. 4.444 diff gets dropped off next week for the lsd install. 4.777 is in the car for now.

I figure 67 mph for S1/S2 combo is around 7200 rpm in 3rd on the 275/35-17. This assumes that I wasn’t able to accelerate more with the lower gear and might be closer to 70 mph (7400) even with the shift and the situation allows for the extra speed. Guess I’m hard-headed and just want to see the the things I’m doing to skew the car towards max accel will pay off.

One is I have this set of 17x9 wheels that only weigh 13.5# each. I hate to give up an 1” of wheel on a 275 Hoosier, but 4 or 5# each less is hard to ignore. Being I’ll probably be a single driver I’d even consider dropping to the 245/40 tire (shorter, adds more gearing, 3rd gear sooner) to get it up to temp faster except it’s only 2# lighter than the 275. Not really convinced all that extra wheel and tire is necessary if the total weight is low enough and the suspension managed properly along with some aero assistance. Still thinking on that one.

Also have the 5.5” mini-clutch setup. Kind of holding my breath on the maintenance of it though. It’s another wait and see scenario. The bolted flywheel and clutch combo is only 8 or 9 lbs total. Launches should be interesting. Drop & go has always been my style so not expecting much of issue there really, just that that I don’t have a feel yet for what the disc wear rate will be.

and more stuff like that ....

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Feel better, Mark! Speedy recovery... hope to see you out in 2018 after you kick this thing's ***!

 

Just my experience, but I haven't had any problem getting 275s up to temp without a co-driver. I'm going with a 295 on a 10" next year. Hopefully it doesn't start rubbing everywhere.

...but of course, your mileage may vary a lot, depending on the weather.

 

I haven't had any problem getting 315s up to temp. We did a ZMax event in November and it couldn't have been warmer than 40 degrees when we ran. I did have a co-driver and my car is a pig but tire heat was not a problem.

Again not RX-8 specific but the 315s did make my car wider... but they also made it faster. I haven't yet found a situation where more rubber isn't better.

Hey so what National events are folks doing this year? I'm planning on Dixie CT, Charlotte MT, NJ, Toledo and Oscoda for ProSolos and am hoping to do Spring Nats.

 

Yeah yeah yeah SM talk again. It sure is easy to fit 315's when you can cut anything you want

We are doing Florida (in an ESP car), Jersey (RX8), and Toledo (RX8) for Pros. Probably the NY tour too. For anyone doing Pros, we are now part of an index class with ESP, DSP, FSP, and STP as an FYI.

 

Everyone should come to the Finger Lakes Tour! Not sure how it'll shake out, since it'll be our region's first national event in a long time, but it'll be fun I'm sure.

Me and my codriver are thinking of doing the NJ Pro and the Toledo Pro for sure, and the Finger Lakes and maybe the Toledo Tour. Then heading for Nats for the first time. Gonna be a busy year.

 

Still unsure, haven't even bothered with the schedule really because you can't go if the cars not ready yet. I haven't done much work on my car given the current circumstances. It will compete this year for sure though. I may skip Pro Solo, or at least not go all out like previous years. I really don't care for the mass registration sign-up deal they use now, though in the past I had laid it all out usually so when you can do that it's ok I suppose.

Thinking I might be under 2800# driver and fuel. My personal weight is only up right now because that's what they want for treatment, but after this is done the belly I used to have won't be around any more. Had dropped 30# prior to this, no biggie to do again. I see wheel/tire size based on that goal, narrower is good imo, but again I've eaten lots of my own poo over the years too. It's all about live and learn ...


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That comment was about DSP, not SM. if I understood Mark correctly he is considering going narrower on tire to keep the car narrower. In my experience, I've never been hurt by going wider. I resisted for years for the same reason and I regret not going as wide as I could sooner.

 

I just remember Bryan Heitkotter winning on 275 Hoosiers in the heavier 330i. Of course I'm not Bryan, but I did stay at a Holiday Inn the night before the event ...

Just the same, my plan right now is to try and initially run my super lightweight 17x9 wheels (13.7# each) with the 275s and see if I can get that to work.

John, what was your 330i weight with fuel & driver?

 

Having driven both the 275's and 295's on my RX8, I'm not sure the 295s are appreciably faster. Or, it comes down to course dependency. The acceleration is noticeably slower, likely due to both how much taller they are and because they are heavier. Sweeper grip is higher, transitionally they are mushier. Personally, I prefer the way the 275's drive, feel-wise. Maybe this next season we will do a back to back test with fresh 275s and 295s.

 

Bryan won in an E36 325i, and I'm pretty sure Dressler had the car on 295/17s that year. He was definitely on 17x10.5" wheels. The 295 needs at least a 10.5" wheel, ideally an 11" to not feel mushy. Doug and Peter tried the 315/18 on a 10" wheel and hated it, but they love it on an 11. I think I could probably fit an 11.5" wheel under the BMW if I could find one to try, but I'm kind of ready to move on...

Mark, my car was 2950 on the scales at Nats in 2017. Which is weird, because the year before it was 2910 with the same fuel and with a heavier exhaust, and I didn't change anything else materially on the car. On my scales at home it's 2920 with the current setup, so somewhere in that range is where truth lies. I'm 155lbs, so with driver call it 3065-3105lbs with driver.

I think Dressler's E36 is in the low 2700lb range (car only).

 

OK, yeah I know 9" isn't ideal and I have numerous 10" - 10.5" wheel sets, just going to try it and see for myself. Which again, I anticipate being under 2800# w/driver & fuel, which is weighing in (hehe) on some of my decisions ...

 

Posted in the technical side with no responses yet,

Hey Guys,

I've done some searching and couldn't find an answer. My rx8 died today after driving for about 15 minutes, car had been on a trickle charger for a few hours after not driving it for a week(small 11lb battery). So I know it's not a battery issue. I was accelerating in 2nd and around 6k it just shut off and died. Coasted to a stop and when I tried to start it I hear nothing. The lights come on and gauges work fine, but there is no starter noise when trying to start the car. no clicking, just silence.

Plugs/wires were replaced a few months ago, on BHR coil pack. Engine replaced 30k miles ago. I'm not sure it it's a fuse, fuel pump, or if the clutch position switch went out and it's not reading that the clutch is in when i'm trying to start it...

Any ideas?

 

 

I'd normally agree, but will make an exception for a DSP brother and friend.

First thing do would be to check fuses & relays. The starter/alternator system has it's own direct circuit/wiring to the battery. You can email me (or text and I'll send you my number) if you need further help.

ps: Facepalmbook is evil. Get out while you still can ...

ps2: Oh yeah, the starter interlock switch on the clutch pedal is another thing to check. Edit: probably not, It only stops the starter from engaging, but has no influence on whether the engine runs or not.






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Check to see if the trigger wire is still attached to your starter solenoid. I've had that happen before at the track.

 

He just emailed me today that it's the engine fuse that's blowing; which kills power to the PCM and will shut the car down just as described, when the clutch pedal is being pushed in.

The only thing that can cause this is the starter interlock switch on the clutch pedal, which I told him. So likely it'll be resolved soon.

EDIT: TopGear8 told me later that it was tripping the fuse even without pushing the clutch pedal in. I suggested that they still test the starter interlock switch to eliminate it before pursuing any other number of other possible things it could be. Sounds like there's short somewhere though.

I think he may have the BHR ignition too, but am not sure if he still does or not. This happened to a few people: https://www.rx8club.com/series-ii-te...lowing-265891/

even though this is a troubleshooting topic, you might not see it otherwise and if you had this problem at an event, which would likely leave DNF, then you might appreciate knowing what the possible solutions are for it ...




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Why would the starter interlock switch cause the Engine fuse to blow? The switch isn't in the Engine fuse circuit...

 

well I didn't look at the diagrams. It was the only thing that could have had an electrical short impact while operating the clutch pedal, so I just drew that conclusion. That has been reported before as also it failing in the open mode and then not allowing the car to start.

although later he said it was blowing without operating the clutch, so I suppose that falls in line with what you said. which would also be more in line to why it blows if there's a shorting wire in the ignition system as the ignition relay turns on

I suppose that's why I'm a mechanical engineer rather than electrical







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Yeah, the Engine fuse circuit touches a lot of stuff. It should be pretty easy to ohm out and find the short by disconnecting various circuits systematically.

 

Found this on my BHR Ignition, wire has been pinched on the engine bracket and worn through down to the copper wire. My guess is this is the issue.

 

Well your neither the first nor likely the last to have that problem

anyone who has a BHR ignition or anything similar need to make sure that none of the wires for it are rubbing up against the engine lift hook the bolts to the LH side (USA driver side) of the water pump and is right at the front backside of the coils. A number of other people have had this same issue with a wire from the coil system rubbing through against the engine lift hook. Which will cause a short that blows the engine fuse, that in turn shuts off power to the PCM and shuts the engine down.



BHR ignition kit wire rubbed through against the engine lift hook/eye and shorted out



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In addition to the above, my latest weight saving scheme is to use update/backdate to also go from the 6-port High Power 12.7” front rotor disc diameter to the smaller 4-port Automatic 11.9” front brakes (both have same thickness) using the same RacingBrake 4-pot calipers. The smaller diameter rotor disc results in a shorter lever arm for the clamping force of the pads; less braking force for a given pedal pressure. I’m attempting to balance this within the range of the Mazda-programmed EBD system (essentially electronic front/rear brake bias via the ABS module) by using less piston area on the 4-pot aluminum rear calipers which are 1” diameter.

By my estimates the net result of both changes is going to be a total 16 lbs. weight cut, most of that due to changing the heavy rear calipers with cast iron mounting brackets for the smaller aluminum mounting brackets & calipers.

slowly chiseling away at it, bit by bit ...

 

While we are still running stock brakes, I have considered testing the automatic brakes on the front. Since we have so much front camber our braking bias is a bit strong toward the front, so I'd be curious to see if that balanced it out. However, I have driven STS miatas that have a stronger rear brake bias and I HATE it.

I believe that brake proportioning valves are also legal in SP.

 

Because of EBD you'll have to disable ABS to use a proportioning valve, which is also an allowed SP modification. You either need to do that or figure out how to reduce braking power in the rear to balance it; which you can't go to a smaller disc so all you can really do is reduce piston area. Not so easy ...

I personally feel like I have way more braking power than needed; it's too easy to over-brake. So I'm hoping it will improve modulation.

Like I posted earlier, the weight loss in the front going to the smaller diameter rotor isn't that much. You still end up with the same swept width, just less of it on the smaller diameter and with a shorter lever arm to act upon. Most of the weight loss from modifying the brakes is in the caliper, caliper mount, and aluminum center hat. If you already have those modifications then you're only going to lose another 1.5 - 2 lbs with that rotor disc change staying within the limitations of the SP allowances.

Otherwise I'd maybe make a cautious warning that it's easy to blame the brakes when in fact other choices are what has caused a bias toward the one end of the car; like excessive spring rate, excessive shock valving, rear diff lockup settings, a combination of those, and so on ...





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