SCCA Autocross setup thread

Discussion in 'Fiesta ST Autocross' started by AlanBDahl, Oct 21, 2013.

  1. Cligedy

    Cligedy Active Member

    Give me til this weekend and I will know if the 225/50-16 will fit. Fingers crossed, it will be a tight fit, especially in the back.
     
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  3. spangenb

    spangenb Active Member

    From another thread we have good data that the 225/45-16 Direzza Z2 fits well
     
    Smokin likes this.
  4. wash

    wash Active Member

    I would like to know if the 225-50r16 BFG Rival fits. It might be better than the Direzza z2 but if it won't fit, the Direzza seems like a good option too.
     
  5. limbo

    limbo Active Member

    I think that'll be course dependent. The z2s were the clear favorite at nationals on a concrete surface. I've heard the rivals may be better on other surfaces ie sealed asphalt.
     
  6. Slowclimb

    Slowclimb Active Member

    I know one guy here running the Rival on a mazda 2 in SMF switched back to the dunlop - stating that the rival did not like to rotate on the small front wheel drive.

    Would love to see some pictures of a ST with the dunlop 225, 50, 15
     
  7. RodMoe

    RodMoe Well-Known Member

    If only they made that size ;) :grumpy:
     
  8. Slowclimb

    Slowclimb Active Member

    Ooops meant 16
     
  9. RodMoe

    RodMoe Well-Known Member

    Ahhh thats fine i had to go back and look see if i missed something new :) oh well i was hoping :)
     
  10. Slowclimb

    Slowclimb Active Member

    Sorry to get your hopes up
     
    RodMoe likes this.
  11. limbo

    limbo Active Member

    Why 225/50/16? Z2's come in 225/45/16 , I've posted a pic of mine on here a couple times (also see profile pic).
     
  12. Slowclimb

    Slowclimb Active Member

    Guess I could go either way, but was thinking that the 50 aspect ratio would offset the smaller wheels impact to gearing. maybe that is not valid?
     
  13. limbo

    limbo Active Member

    The 225/45 is actually closer to the stock diameter than 225/50.
     
  14. Slowclimb

    Slowclimb Active Member

    Still the taller ratio could improve top speed in 2nd....waiting to see how people's set up shake out anyway. So have time to make a less hypothetical decision.
     
  15. Cligedy

    Cligedy Active Member

    225/50R16 rivals show 60.4mph at the top of 2nd. Stock is 58mph
     
  16. AlanBDahl

    AlanBDahl Active Member

    Remember you have 17 more horsepower in 3rd vs 2nd. This has made me wonder if shorter tires might be better on fast courses.
     
  17. Cligedy

    Cligedy Active Member

    17hp at peak, which is 6000rpm; to get to that engine speed in third would have you at 83mph (on stock tires). I know that every region and course are different, but not many runs will have you above 65mph. Changing at 55mph would have you at 4000rpm in third, which is still in the meat of the powerband, but if you drop down to 45, thats ~3400rpm, and falling out of the sweet spot.

    This is not the slickest shifting car I've ever driven, so a bunch of shifts on course don't seem like the answer, but maybe the shorter gearing would keep you in the power better. Have you decided what tires you are running yet? Are you planning on running multiple sets?
     
  18. Slowclimb

    Slowclimb Active Member

    Right....there is no way I will be using 3rd very much. There is only one course that I have run that I have been tempted to shift up in, and after some tries it turned out that bouncing the limiter was the quickest way to get around. The time to shift up and shift back down negated any extra mph you got. This is one reason some Miata owners take the 6 speed out in put in a 5 speed, to get the higher top end in 2nd.
     
    Last edited: Jan 16, 2014
  19. AlanBDahl

    AlanBDahl Active Member

    Perhaps I should instead have indicated that you have more boost in 3rd instead. It would be interesting to compare 50-60 times in 2nd using the D2s vs 3rd using the Toyos. Sure you will loose time to shifting but on faster courses (I've driven half of one of our local sites in 3rd before in the Solstice) it might pan out. In addition on some Pro Solo courses I've barely hit 50 and once again the short tires could be the ticket.

    BTW I am not advocating for running short tires all the time but a dual-prong approach with two sets of wheels and tires could be an interesting one if you're running near the top.
     
  20. Slowclimb

    Slowclimb Active Member

    Point taken...I am sure there are courses where there could be benefit and it may be interesting to do a comparison. Unfortunately I don't have the funds in my autocross budget for that right now. Most have been allocated to rebuilding my 64 beetle.
     
  21. Couldahadav8

    Couldahadav8 Active Member

    Peak horsepower is less important, I think, than the stronger torque numbers throughout the meat of third gear. The dyno torque numbers out there are more impressive than the already impressive horsepower numbers. The idea of going small is enticing. Reduced rotating mass and lower center of gravity would be nice side effects as well.
     

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