Tarmac 88 "Button" GLTC/ST5/TT5
#284
A failed valve cover gasket caused a big ol’ mess at Laguna Seca. So, a fresh OEM Mazda piece was installed tonight. I discovered a broken coil pack mounting bracket, so I had to swap in my last known-good spare.
If it brakes again, I’ll be forced into a TSE CoP upgrade, clearly. Totally.
Also on the list was to cut and fish out the hood catch loop. Grams yo. Racecar weight weenie-ing continues.
Also: Don’t Suck covering my worthless oem speedometer. (4.3/6spd)
If it brakes again, I’ll be forced into a TSE CoP upgrade, clearly. Totally.
Also on the list was to cut and fish out the hood catch loop. Grams yo. Racecar weight weenie-ing continues.
Also: Don’t Suck covering my worthless oem speedometer. (4.3/6spd)
#285
Not sure if this question is suitable in this thread..? (or even confidential).
Is the splitter length in the various photoss of 949 cars one decided upon by performance or one decided on via rules?
i.e. we run quite a bit longer (approx double what I see here, if not slightly more) and wonder if this is just more drag for little benefit....
Is the splitter length in the various photoss of 949 cars one decided upon by performance or one decided on via rules?
i.e. we run quite a bit longer (approx double what I see here, if not slightly more) and wonder if this is just more drag for little benefit....
#286
Most rule sets limit us to 4”. In US club level racing, aero is seen as dark art and really exspensive. Rulesets either simply don’t allow aero mods, or severely limit the allowed aero mods.
We set the Supermiata S1 class aero rule to match the “norm”, as it’s a common figure and helps class to class crossover.
The book “Competition Car Aerodynamics” references nascar/StockCars and 5” as the point of max efficiency in that application.
In practice, if I was allowed 5”, I’d probably end up needing two splitters, as my car is fastest currently with the wing at zero or negative AoA. One for slower tracks and a smaller one for faster tracks. More splitter requires more wing to balance, and more drag. My horsepower level doesn’t approve of any more drag.
More power means drag is less of a concern, generally.
949/Supermiata cars built to more open rulesets have used splitters as deep as 10” and wider than the track width.
We set the Supermiata S1 class aero rule to match the “norm”, as it’s a common figure and helps class to class crossover.
The book “Competition Car Aerodynamics” references nascar/StockCars and 5” as the point of max efficiency in that application.
In practice, if I was allowed 5”, I’d probably end up needing two splitters, as my car is fastest currently with the wing at zero or negative AoA. One for slower tracks and a smaller one for faster tracks. More splitter requires more wing to balance, and more drag. My horsepower level doesn’t approve of any more drag.
More power means drag is less of a concern, generally.
949/Supermiata cars built to more open rulesets have used splitters as deep as 10” and wider than the track width.
#287
I read that book but didn't see the NAscar 5" info, will have to check again.
Thanks for the info.
Presumably 300 - 350 whp is what you have in mind for the running of more than 4-5" of splitter?
I tried a 3" at Pukekohe (high speed, 5-6th gear turn 1) and had a big, sudden front lose, so very quickly dropped that low downforce philosophy
May need to revisit.
Thanks for the info.
Presumably 300 - 350 whp is what you have in mind for the running of more than 4-5" of splitter?
I tried a 3" at Pukekohe (high speed, 5-6th gear turn 1) and had a big, sudden front lose, so very quickly dropped that low downforce philosophy
May need to revisit.
#288
As Dan clarified, S1 aero was designed with a clean sheet of paper. Compatibility with other classes, a useful adjustment range plus or minus, and also relative toughness when the driver chucks it off track now and then. The other constraint was also a desire to remove any "secret sauce" from the build recipe. While it's sexy to have some highly functional flat bottom and diffuser, very few DIY Builders know how to put one together cheaply. The rear wing is clicking a button on Singular Motorsports website. The basic front we do is highly documented so even a noob builder can cheaply put one together with basic tools.
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#289
Sonoma was a blast. Bucket list track. Years of Forza/Gran Turismo paying off in real life.
Car was hampered with an oiled clutch from a failed valve cover gasket that shut down my 2nd day at Laguna. My attempts at R&R, cleaning and scuffing between events were unsuccessful in recovering the torque capacity. I was forced to tip toe around at about 80% throttle or it would slip in 4th or 5th gear. So I set pressures in the RC1s once on Saturday and never touched the car again. I took the ST5-spec Hoosier R7s, but never bolted them on. Spent my time on track harassing the SPM S2 guys and had several dicing sessions with Jeff Ringer and Erin Kennelly. I'll try to get that video chopped up on its own, as bumpdrafting is always fun.
Several 1:55's on predictive that bled away on the uphill dragstrip from T6 to T7 because of the clutch slippage.
Late on Sunday the RF hub called it quits.
A 10 hour tow probably makes Sonoma a once-every-couple-years destination, but I can't wait to go back. All in all, super fun HPDE on a super fun track.
To do:
RF hub replacement
Cylinder head swap
new clutch disc
Dyno appt
Continue dropping weight
Car was hampered with an oiled clutch from a failed valve cover gasket that shut down my 2nd day at Laguna. My attempts at R&R, cleaning and scuffing between events were unsuccessful in recovering the torque capacity. I was forced to tip toe around at about 80% throttle or it would slip in 4th or 5th gear. So I set pressures in the RC1s once on Saturday and never touched the car again. I took the ST5-spec Hoosier R7s, but never bolted them on. Spent my time on track harassing the SPM S2 guys and had several dicing sessions with Jeff Ringer and Erin Kennelly. I'll try to get that video chopped up on its own, as bumpdrafting is always fun.
Several 1:55's on predictive that bled away on the uphill dragstrip from T6 to T7 because of the clutch slippage.
Late on Sunday the RF hub called it quits.
A 10 hour tow probably makes Sonoma a once-every-couple-years destination, but I can't wait to go back. All in all, super fun HPDE on a super fun track.
To do:
RF hub replacement
Cylinder head swap
new clutch disc
Dyno appt
Continue dropping weight
#292
Right, that's the part that I thought was impossible due to how tight the two are bolted together and because that oil is only driven by gravity and possibly air moving over it, so it's not like there is any pressure to really push it into the smallest of openings. I've taken transmission off only once and don't remember there any major openings except for the starter, but even that one appeared well protected.
#296
I am scratching NASA Buttonwillow off my calendar. I could have done a quick cylinder head r&r and shipped it to the dyno, but I would rather take my time and do a few extras 'while I'm in here'.
My psuedo-Supermiata-whammy, Keegan Engineering built BP4W head has arrived.
I was greedy and asked Mike to give me the "80/20". I needed 80% of the gains, and wanted to spend 20% of the money. What he, emilio and I came up with was as such:
Non-CNC-Supermiata/Keegan Engineering ported BP4W
-Valves de-shrouded, blended
-Bowl work and plunge cuts blended out to the valve guides on the intake side.
-Exhaust ports fully hand ported from bowl to manifold
-Casting flash and core shift ridges knocked down, but not totally smoothed out, remember 80/20)
Supertech +1mm valves
Supertech Light Double Valve Springs
Stock BP4W lifters
Skunk2 throttle body
Mazda BP5A intake cam
Mazda EUDM/JDM squaretop intake manifold(I'll be porting this to match the S2 TB diameter)
165whp is the goal.
That will allow me to ballast up to the 2400lb (or 2450lb break-point depending on proposed rule change for 2019) and open up 225/45/15 Hoosier R7(257mm section width)
Currently, parts and gaskets I forgot to plan ahead for are in the mail.
My valve cover and intake manifold are at the powder coater.
I am taking this opportunity to install an oil cooler and Supermiata Crossflow radiator, as well as correct my ducting situation and add a mesh grill to my airdam.
My psuedo-Supermiata-whammy, Keegan Engineering built BP4W head has arrived.
I was greedy and asked Mike to give me the "80/20". I needed 80% of the gains, and wanted to spend 20% of the money. What he, emilio and I came up with was as such:
Non-CNC-Supermiata/Keegan Engineering ported BP4W
-Valves de-shrouded, blended
-Bowl work and plunge cuts blended out to the valve guides on the intake side.
-Exhaust ports fully hand ported from bowl to manifold
-Casting flash and core shift ridges knocked down, but not totally smoothed out, remember 80/20)
Supertech +1mm valves
Supertech Light Double Valve Springs
Stock BP4W lifters
Skunk2 throttle body
Mazda BP5A intake cam
Mazda EUDM/JDM squaretop intake manifold(I'll be porting this to match the S2 TB diameter)
165whp is the goal.
That will allow me to ballast up to the 2400lb (or 2450lb break-point depending on proposed rule change for 2019) and open up 225/45/15 Hoosier R7(257mm section width)
Currently, parts and gaskets I forgot to plan ahead for are in the mail.
My valve cover and intake manifold are at the powder coater.
I am taking this opportunity to install an oil cooler and Supermiata Crossflow radiator, as well as correct my ducting situation and add a mesh grill to my airdam.
Last edited by doward; 10-24-2018 at 10:57 PM.
#298
Dang, 165+whp sounds nice. Assuming I venture to ST5 (highest possibility of current options) I'd like to do something like that + maybe Mazda 10:5:1 pistons and some bottom end bullet proofing. 170 peak on e85 with 6 speed and aero would be a lot of fun. Mo' power is also the only way I'd ever expect to hang at CoTA (or in general) with S2k, FT86, Bimmers, etc. Can't wait to see this setup action.
#299
Not much more power with bigger pistons and more compression. BP's are honey badgers WRT to compression. Don't need a lot regardless of what you are doing. Gains from bore are linearly related to bore increase, i.e, small.
Dan was smart to spend his modest budget on a good head build that will work for anything. With the demise of NASA PT, there is no reason to build a stock or "points" head anymore. He spent roughly 2.5x what an OEM head/(stock cam) rebuild would cost but it's future and over rev proofed.
If you are in the bottom end and have the budget, by all means, 85.5's and 11.0:1. Otherwise just focus on the head.
It would be cheaper to put big cams in it, make 185whp on a stock bottom end. Just gotta watch the revs on stock rods.
Dan was smart to spend his modest budget on a good head build that will work for anything. With the demise of NASA PT, there is no reason to build a stock or "points" head anymore. He spent roughly 2.5x what an OEM head/(stock cam) rebuild would cost but it's future and over rev proofed.
If you are in the bottom end and have the budget, by all means, 85.5's and 11.0:1. Otherwise just focus on the head.
It would be cheaper to put big cams in it, make 185whp on a stock bottom end. Just gotta watch the revs on stock rods.
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#300
I had planned to do a bottom end as well, Keegan has my core torn down and cleaned for whenever I'm ready. The $/whp ratio doesn't work for me, and the headroom/insurance cost of rods, fresh bearings, labor, etc just to end up using OE pistons is a non-starter for an N/A motor in an average-power rated class. So I cancelled that half of the project. That $3-4000 bottom end build goes back into my budget as a whole season's worth of entry fees, or a used rotrex...