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Thread: SRA - data/numbers to keep an eye on on track?

  1. #1
    Gluon
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    SRA - data/numbers to keep an eye on on track?

    I will be driving my new SRA for the first time this weekend. What data inputs are being tracked/displayed by the Dash2 (ie coolant temp, oil pressure, oil temp, etc), and what are the nominal/danger ranges for each?

    Are you guys running 18 psi front/20 psi rear as suggested by the factory?

  2. #2
    Ion
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    My SRA (chassis 34, built in Dec 2012, K20) only showed RPM and water temp when I got it...thats it. There was an oil pressure sensor wired into the Dash but no reading. I suspect the sensor was bad but not sure. I'm replacing all that with a AiM MXS dash that will show me: Speed, RPM, Gear, Water temp, Oil Pressure and Oil Temp plus all the data logging and smarty cam video.

    Running hot hasn't been a problem - at least water temp. Last year on summer days I was seeing around 210 F. The SRAs don't have thermostats and I've had problems getting the water hot enough on a cold day - seeing only about 165. I've been told that during the race series at VIR, on cold days, they'd block off the radiator with cardboard to limit airflow in an attempt to get the temps up.

    I ran 18psi square most of the time last year on well worn R7s.

    First time with SRA - have fun! For me, at first I thought it was a really tricky car to drive. Your inputs have to be so subtle and smooth because the car reacts instantly. So different than a tin top street car. It also alternates between crazy understeer with the light front end and scary oversteer if you are not careful with trail braking and throttle tip in. But after about 6 days on track I really got comfortable with it.

    Cheers!
    Last edited by argonaut; February 19, 2019 at 05:43 AM.

  3. #3
    Ion
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    I'm very surprised the SRA cars do not come with a thermostat, I've built drag race, road race and endurance race Honda engines, most have been very successfully raced for several seasons and won many races, I used original production Honda thermostats in every one. It's important for the engine to be at operating temperature for the oil to flow properly and for the metal parts to be at the correct clearance. Any other SRA owners out there with some input

  4. #4
    Gluon
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    Reporting back after my first weekend in the car (last weekend, not this weekend).

    Made the mistake of going out in 35 degree, overcast weather. I was so anxious to drive the car for the first time that I didn't care the tires (BFG R1S) were never going to get up to temp. Big mistake... slid off track into the grass even though i was crawling at <30mph, so decided to call it for the day.

    The next day it was 55 and sunny, which made a big difference. Still didn't get the tires fully up to temp, but was able to at least drive the car somewhat normally. @argonaut, your point about being smooth on inputs is 1000% accurate. My coolant temp never got above 175, so i may try the cardboard trick next time out if it's chilly again. I started the day with 15 psi front/rear.

    Things that struck me:
    1) inputs need to be very smooth to maintain balance
    2) the atom has the aerodynamics of a brick. Letting off the gas felt like pressing the brakes almost with the amount of wind resistance/car slowing on its own.
    3) non-hot tires make the car nearly undriveable
    4) open cockpit is AWESOME
    5) rear visibility is zero

    I'm still shaking down the car and getting things fitted to me (seat/pedal placement, etc), and having a rear view monitor/camera installed which will make me a lot more comfortable having better situational awareness on track.

    Absolutely love the car overall. Can't wait to get familiar with the car and be able to push it for real vs tip-toeing around the course as I am currently.

  5. #5
    Ion
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    Glad to hear you enjoyed your outing, even if the temps were less than idea.

    Funny story about the aerodynamics: as you observed, the aerodynamics are terrible. But when following another Atom, this makes the drafting possibilities very interesting. If you've ever watched any YouTube videos of the SRA races you'll notice they do a lot of drafting and for the most part, the guy in the back has the advantage on a long straight as he can slingshot past to take the lead quite easily. Watching it on video is one thing, but doing it on track is quite another. I've played lead/follow with another SRA a couple times now and its a lot of fun to come out of a corner onto a long straight on the tail of your buddy and just sit in their 'bubble'. Suddenly you use about 1/2 the throttle and there is a fraction of the wind noise and buffeting - literally at any point you can step on the gas and just zoom by him. It makes you realize how drafting works, like in Nascar racing.

    I've come to the conclusion that - of the mainstream tires* - the only one to get is Hoosier A7 or R7. I've tried a brand new set of R1S (heat cycled and broken in properly) a couple times and just hated them compared to the Hoosiers. A friend tried shaved RA1s on his and hated them. *Some guys have noted using true racing slicks, like formula Atlantic tires, is the best. But they have funky sizes, are hard to get and quite expensive.

    For rear visibility - I have a set of aftermarket motorcycle mirrors that are great. They stick out further than the stock ones, are much higher quality and give a superior rear view. I talked to an Atom owner with rear view camera on track and he liked it (but he had stock mirrors) but said that it really vibrated around a lot, so the rear view was kind of like - 'I know something is behind me and gaining, but I can't really tell what'. I've considered adding one but am happy with the mirrors for now.

  6. #6
    Gluon I want an atom's Avatar
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    I did karting for awhile- hope to get back at it again soon. A lot of them actually have a little movable air shield over the radiators to close up on colder days to help get engines up to operating temps. So I see no reason why the atoms wouldn't be any different, meaning the cardboard would seem like a viable idea. Now if they could just get mine registered I could start having fun.

  7. #7
    Gluon
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    @argonaut, I wanted to get the A7s but they don't come in the stock SRA sizes (205/50/15 front, 225/50/15 rear). What size A7s do you run?

    From reading other posts on here i've heard to stay away from the R7s due to never getting up to the proper operating temp window. If the A7s aren't available in the sizes i need, would you suggest just going R7 over BFG R1S, temp window be damned?

  8. #8
    Lepton cvjoint's Avatar
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    Another Atom on track is super! Let us know what you have difficulty with, the learning curve is steep but feels so good as you improve, there is nothing like this from other manufacturers.

    To answer the original post:
    *Coolant: can get up to 218* on a 103* ambient day without traffic. I've seen 225* drafting other cars but as you can imagine there is no limit and can boil over if you do it for too long. The front radiator is small and can get easily covered while drafting by today's giant track cars. This is on a stock K24Z7 SRA.
    *Tire PSI: I run between 16 psi and 18 psi to start and aim for 20 psi. This is on Formula Atlantic slicks. I run a bit more on Hoosier H2Os because I used them on the relatively super narrow stock wheels and don't like how they roll off the rim. With narrow wheels there is generally a tradeoff between good transient feel in S curves (with high psi) and good heat in the tires (with low psi). Generally the hotter the tire the faster you go with this car, so low psi is better for speed but ruins feel and feedback if the rim is too narrow.
    *Oil PSI: We cannot datalog so it's tough to say. My VTEC always works so that's my "idiot light" for low oil pressure. The K24Z7 Atoms do not have oil starvation issues. However, be sure to top off oil often, these engines gulp a bit and that's one way to fry your bearings.

    Other tips:
    *Use the softest possible compounds at all times: R25B/A7/H20 from Hoosier work really well. R25B is discontinued in most sizes, R35 is almost as good but needs more heat than the other three. Avons work as good or better but don't remember the compound designation. You want the autocross or hillclimb Avon compounds.
    *On cold days or if you are not an advanced driver it's better to run narrow tires as well.
    *Instead of cardboard use gaffer tape like the rest of the race cars. I apply them to the sides of the nose cone covering about 50% of the surface on 45*-55* days.
    *I tried to have a shop install an OEM thermostat but it's not easy. The thermostat would not open easily, probably because the cooling circuit is too large and there is unequal heat on the sides of the thermostat. That or we need to re-route the coolant lines. Not sure, haven't tried again after that. The length of the cooling pipes is much longer than in a Civic and I'm not convinced slowing the cooling water flow is any good so I'm staying with the no thermostat solution for the foreseeable future.
    *tighten the axle nuts often, you will need two sockets for front and one super large socket for rear.
    *I use cheap Spec Racer Ford mirrors because I brake as many as two per track days from rocks and they work better than OEM. I use 3M foil on them so that when the glass brakes it stays on the car instead of getting thrown at other cars as debris.
    *Get a HANS device to keep your head on your shoulders, literally.

  9. #9
    Ion
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    To be clear - I have not yet tried A7s, only R7s. On warm days I can easily get the R7s up to temp and they have worked really well - I like them much better than the BF Goodrich. I do want to try the A7 but you are correct about the sizing. I have a extra pair of 16x8 rims for the rear and extra pair of 15x7 for front, so I could try 15/225/45 on the front and 16/245/45 on the rear. The stock rear tires are about 1 inch larger diameter than the fronts. This setup would about about 1.6 inch difference.

    Hoosier A7 15 /205/50 22.8 5.5-7.5
    Hoosier A7 15/ 225/45 22.8 7-8.5
    Hoosier A7 15 /245/40 23 8-9.5
    Hoosier A7 15/ 275/35 23 9-11
    Hoosier A7 16 /205/45 23 7-8.5
    Hoosier A7 16/ 245/45 24.4 7.5-9
    Hoosier A7 16 /225/50 24.7 6-8
    Hoosier A7 16 /275/45 25.6 8.5-9

    I haven't bought tires yet for this season, so still have time to decide.

  10. #10
    Lepton cvjoint's Avatar
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    My thoughts on R7 is that it's impossible to get up to temp. I ran consistently for 20 minutes near the top of the advanced group at Sonoma Raceway which is hard on tires on a 90*+ day and could only pump 170* in the rear 225 section R7. R7s need about 200* for peak grip, and the low bound according to Hoosier is 180*. That's the closest I got. I ditched R7 and never looked back. The soft compounds give me 1.6G to 1.7G without aero depending on the track which is well over the 1.3G I got from R7. Between laptimes, lateral G, and pyrometer readings I'm convinced R7s are easy to improve upon.

    Two pairs of rims is the way to go on this car. I use the wet tire set on cold days or mix and match dry and wet compounds to run fast regardless of the ambient conditions.

    I prefer Atom's difficulty to build heat into tires over today's 3,500lbs+ sports cars anyday. We can fix all our grip problems by going with soft compounds which are the best compounds anyhow.

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