+ Reply to Thread
Page 2 of 4 FirstFirst 1 2 3 4 LastLast
Results 21 to 40 of 76
Like Tree114Likes

Thread: Building an Exocet for ST2/3

  1. #21
    Senior Member fatbillybob's Avatar
    Join Date
    Sep 2008
    Location
    by the beach
    Posts
    1,974
    Liked
    1583 times

    Default

    Quote Originally Posted by Blackbird View Post
    I doubt it, Carl doesn't do el-cheapo V8 Ferraris, he's a Ferrari V12 kinda guy
    LOL! Here is a little V-12 cam timing work. I love doing this stuff!

    20141212_190407.jpg

  2. #22
    http://www.trackhq.com/Banners/yellowsitesponsor.gif Blackbird's Avatar
    Join Date
    Apr 2012
    Location
    Northridge
    Posts
    2,251
    Liked
    1956 times

    Default

    You should come visit me once I have the engine in the car... I'm assuming you saw the Morpheus thread update, right?

  3. #23
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    Hey Blackbird, thank you for the response, but respectfully, I don't think it is accurate. My understanding is that MEV (originators of the Exocet) incorporated shock towers that were too tall. When people converted their Miata over, and used the stock suspension pieces - the higher shock towers effectively lowered the car without the need for a coilover kit, etc. When Exomotive refined the design and started building the cars here in the US, they kept these same "high" shock tower mounts. Ironically, it wasn't until chassis 30-something when a customer of Emilio's (he's actually been over here to our shop to check out our build) "discovered" this problem.

    The problem was as you mention - the car was too low (a-arms not level) AND many (most?) coilovers would have interference problems with the inner part of the a-arms. I guess it was much better that the towers were too tall rather than too short - because the "fix" was a relatively simple one. For a LONG time now, Exomotive has relatively inexpensive spacers that restore the towers.... and therefore ride-height to oem specs.

    Hence my question to Emilio.... allegedly he knows all of this but continues to repeat that there are geometry issues - of which our research shows there are not.

  4. #24
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    Man up an accept that not everyone will think you are gods gift to driving, or race car engineering.
    Man, you are from a different planet. You got THAT out of my posts? Seriously? My post of a half-finished chassis going off to powdercoating?

    Let's get this back on track..... you, the reigning emperor of race car engineering, allege that the Exocet has suspension geometry issues. Please elaborate.

  5. #25
    http://www.trackhq.com/Banners/yellowsitesponsor.gif Blackbird's Avatar
    Join Date
    Apr 2012
    Location
    Northridge
    Posts
    2,251
    Liked
    1956 times

    Default

    Admittedly, I haven't been following much on Exocet developments so it may very well be that yesterday's problems are fixed.
    I did look at the car back when they arrived at the US and spotted the issue right away, but didn't feel like I want to rain on the parade by voicing it...
    Setting the shock towers too high up the chassis lowers the subframes assuming stock length shocks and screws up the geometry, switching to aftermarket coilovers makes it even worse because typically they have shortened body (meaning the car sits even lower).

    At any rate, if you know it's all fixed, more power to you.
    Build your car and make the point come across by winning some races

  6. #26
    http://www.trackhq.com/Banners/yellowsitesponsor.gif emilio700's Avatar
    Join Date
    Aug 2007
    Location
    SoCal
    Posts
    3,707
    Liked
    2504 times

    Default

    The sarcasm isn't really needed is it?

    I get why you are angry. No one likes to be told their brilliant idea might not be as brilliant as they thought. How you chose to deal with that is just that, your choice.

    You are erroneously assuming something about me. I'll only voice an opinion about things I have direct personal experience with. Those comments are worth exactly what you paid for them. I publish my mistakes too.

    I have not criticized, voiced no sarcasm, have not belittled your skill or resources. Have not made personal attacks. Trust me, you are going to remain an outsider on this forum if you keep up with the hate. But have it your way.

    When the Exocet is raised to a ride height where the control arms put the roll centers where they would be in an equal Miata, the frame is between 8-11" off the ground. Most of the Exocets I see pics of have their upper ball joints near the end of their range of motion.
    Perhaps you have heard of the few random upper ball joint failures in Exocets? This is the cause. No Exocet owner wants to run their cars that high because it doesn't look cool. So they lower them until the shocks are nearly bottomed and ball joints are straining.

    We saw early Exocets (pre shock spacer) with shocks completely topped out, not "figurative" but functionally topped out when at static ride height. Ball joints locked at max angle. Control arms at a 50° angle. Gruesome when one knows how sweet a Miata can handle when set up right.

    Exomotive also designed the chassis assuming all builders (UK market) would use the OEM 14x6 wheels from the NA8. The marketing concept was a super low budget garage build type of car for the UK market. Thus the frame was built really close to the rear tires. When the car came to the US market, the cost of the kits increased and a new demographic with a lot more project budget emerged.
    Everyone wanted much wider tires because.. America! The wider wheels fouled the frame. So it was either stick with a narrow wheel with the correct offset or radically lower the offset to get the extra width. That change in offset has a profound and deleterious effect on scrub radius, wheel rate, toe curves and motion ratio.
    A quick way to ruin the handling of a Miata is to switch from the sweet spot near OEM offset to zero offset wheels.

    We put a 15x8 +0 6UL into production just for the Exocet and have a 15x9 +12 6UL for it in the pipeline. We are also developing an extended length Xida coilover, again for the Exocet.

    But honestly, I think I'm wasting my time. You only want confirmation of what you already believe, not a contrasting point of view.


    If you feel I have overtly disrespected you at any point, I apologize.

    If, OTOH, you are simply angry that I respectfully questioned your rationale and that irks you, then welcome to TrackHQ!
    Olitho and Force McCocken like this.
    WWW.949RACING.COM
    SuperMiata

    Aside from their cost I never understood why people race them.
    But obviously I just dont get it. -fatbillybob

  7. #27
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    No, you are not wasting my time, but you ARE proving my point. From your description there are 2 "issues". First, a lot of people setting up the cars to run too low because they want to "look cool" – and this compromises roll radius and puts stress on ball joints, etc. This was even a bigger problem before Exocet came out with the spacers. But this is easily corrected, right? Simply go with a ride height that is more conducive to best handling attributes. (I do want to verify your 8-11” frame height assertion as it seems a little exaggerated but we’ll come back to that another day.)
    The second issue is the chassis design which (somewhat severely) restricts wheel choices. Nevertheless, a 15x7 or even a 15x8 wheel with a 25mm offset and a 205 tire will fit. Wider rims/tires can be used if you compromise offset to 0. We intend to experiment with these combinations. My gut tells me that at 1750-1800lbs and 175-180HP, the ideal tire will be a 205 or 225.
    That said, if we compare apples to apples – let’s say our current Spec Miata with 15 x7 and 205’s to a PROPERLY set-up Exocet with the same wheels/tires – the Exocet will have NO suspension geometry issues and, in fact, will be identical to the Spec Miata (geometry-wise). But the Exocet will weigh 600-700 lbs less than the SM. Even with an Aero disadvantage, I would think that the Exocet will be significantly faster on tracks like Buttonwillow. Well, we ARE going to find out!

    I’m trying to come back to your initial assertion…

    From experience, the Exocet is slower than a Miata with the same power, despite being much lighter. The suspension geometry and aero issues handicap it.
    Respectfully, I think there are a LOT of tracks where this just won’t be the case. 600-700lbs is a LOT of weight. A full body Miata will have higher straightaway speeds – I think we agree, but the weight difference is going to be in favor of the Exocet in braking, cornering speeds and acceleration through 60-70mph.

  8. #28
    Member
    Join Date
    Sep 2016
    Posts
    52
    Liked
    41 times

    Default frame

    What is the weight of the new ND rollerskate "power plant frame"?

  9. #29
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    What is the weight of the new ND rollerskate "power plant frame"?
    Not sure if anyone has yet ventured in to stripping a new ND down to the rollerskate......

  10. #30
    http://www.trackhq.com/Banners/yellowsitesponsor.gif Blackbird's Avatar
    Join Date
    Apr 2012
    Location
    Northridge
    Posts
    2,251
    Liked
    1956 times

    Default

    Ron Bauer has, but IDK if he weighed it.

  11. #31
    Senior Member
    Join Date
    Sep 2011
    Location
    Rolling Hills Estates
    Posts
    2,981
    Liked
    871 times

    Default

    Quote Originally Posted by CoolTech View Post
    Emilio - nice post... now you want to take the high road.

    I post the fruits of a lot of our labor and expense and you piss all over it - then you accuse me caustic criticism? . . .

    "Not trying to troll you, or rain on the parade. Just suggesting you might temper your expectations that may conflict with known data points. my .02"

    Wherein lies the urinary affront in Emillio's initial response?
    Last edited by Loose Caboose; 06-01-2017 at 03:17 PM.
    bellwilliam and Red_5 like this.

  12. #32
    http://www.trackhq.com/Banners/yellowsitesponsor.gif emilio700's Avatar
    Join Date
    Aug 2007
    Location
    SoCal
    Posts
    3,707
    Liked
    2504 times

    Default

    Quote Originally Posted by Loose Caboose View Post

    "Not trying to troll you, or rain on the parade. Just suggesting you might temper your expectations that may conflict with known data points. my .02"

    Wherein lies the urinary affront in Emillio's initial response?
    I think we're past that conflict. Let It Go.
    WWW.949RACING.COM
    SuperMiata

    Aside from their cost I never understood why people race them.
    But obviously I just dont get it. -fatbillybob

  13. #33
    Senior Member CharleyH's Avatar
    Join Date
    Jan 2014
    Location
    Orange County, CA
    Posts
    349
    Liked
    204 times

    Default

    Looks like a fun build. Enjoy! I'm looking forward to seeing it out on the track. Be sure to post progress pictures.

    Charley
    Olitho and BOWERSdaAZIAN like this.

  14. #34
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    Knowing that we were starting this build to enter it into ST3… and with our research showing that the race frame with fluids and driver was going to be ~1750 lbs, our target HP was going to be in the neighborhood of 175HP (10:1). (Maybe a little less after some rule “adjustments”.)

    So the question was, what did we want to do for power? I should add one more thought. In addition to ST3, we also want to use the car for endurance racing so wanted to have a lot of emphasis on simple and reliable. Although we have some forced induction experience, we decided that we just didn’t want to go down this path with a dedicated race car. In the past couple of years we built a few Miata engines with 11:1 piston, flat top manifolds, megasquirt, etc and these typically netted out in the 160-170HP range. However, we simply had no good data points as to their reliability and we knew we would stretch them even further if we needed to pull a continuous 170HP from them. We opted against a V8 – a lot of people going down that path with Exocets but our target was LIGHTWEIGHT and balance.

    After a lot of consideration (and pretty naïve about TOTAL cost to pursue this path), we decided to use a relatively stock Honda K24A2. These powerplants are pretty amazing and when swapped into a Miata using a custom header and aftermarket intake, they make about 220+ at the wheels. On top of that, the K24 is ~30lbs LIGHTER than the Miata 1.8. From a reliability perspective, the Honda has a good reputation and the thought that we will have to de-tune it for rules compliance seems like it will further improve already good reliability. One of the more attractive things about the Exocet when compared to similar cars (Ariel Atom?) is that the Exocet keeps the Miata’s excellent F/R weight balance. We’re hoping the K24might even help us to improve upon that.

    Anyway, here’s a few pics of the skateboard with the K24… and then the mods we’ve had to make to the hood.

    img_5114.jpg

    img_5118.jpg

    img_5238.jpg

  15. #35
    BMW Master bawareca's Avatar
    Join Date
    Jan 2011
    Location
    LA
    Posts
    1,747
    Liked
    673 times

    Default

    Quote Originally Posted by CoolTech View Post
    From a reliability perspective, the Honda has a good reputation
    Alonso will strongly disagree

  16. #36
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    Alonso will strongly disagree
    Boy Howdy!! I walked into that one!!

    OK, how about the K24 has a DECENT reputation?

    That said, we have concerns about oiling so we did fab brackets and will be using an Accusump from day 1.
    Olitho and bawareca like this.

  17. #37
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    From the pic, you can see that the oil pan straddles the steering rack and leaves the front of the pan very exposed. If you look back at Post 1, you will see we added a U-shaped bar to fit in front of the pan. Seen too many busted pans from inadvertent race track "excursions".
    BOWERSdaAZIAN likes this.

  18. #38
    Administrator ucfbrett's Avatar
    Join Date
    Jan 2009
    Location
    Ventura, Calif.
    Posts
    5,545
    Liked
    2305 times

    Default

    How does the oil that falls into the section of the pan in front of the rack return to the sump? Is there transfer tube we can't see?

  19. #39
    Senior Member
    Join Date
    Apr 2017
    Posts
    148
    Liked
    67 times

    Default

    How does the oil that falls into the section of the pan in front of the rack return to the sump? Is there transfer tube we can't see?
    No, I guess it just stays there. The pan itself is pretty complex - incorporating a couple of hinged flappy doors. The "full" oil level is about 1/8 above the TOP edge of that part of the pan. A couple of days after first seeing the pan, we ordered the Accusump. LOL
    ucfbrett likes this.

  20. #40
    Senior Member
    Join Date
    Jul 2008
    Location
    Los Angeles
    Posts
    327
    Liked
    222 times

    Default

    Neat project! Looking forward to seeing the build posted here.

    Can you still change out the steering rack without pulling the motor (w/ that pan)?

    What additional allowances did you have to make with the k24 for clearance and where? e.g. looks like the motor is a few inches forward compared to normal Miata position(?)

+ Reply to Thread
Page 2 of 4 FirstFirst 1 2 3 4 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts