NEW EFR?
#81
Could be, but that would surprise me since it's a radial tire. It's a substantial reduction, over an inch of circumference loss IIRC. I don't actually have a good theory for why the GPS speeds are lower than the calculated speeds, but I do have a bunch of repeatable data that shows it to be true
#85
I wonder if it's a result of intentional unilateral tolerancing. Ever notice how every car's speedo tends to be a little too optimistic? I have to think it's driven by liability concerns of the manufacturer which make them tolerance the speedo to over report speed rather than under report speed. Perhaps the gear ratios and therefore top speed of a gear at a given RPM is also slightly unilaterally toleranced to avoid exceeding the limit of the design envelope. Just an armchair conspiracy theory.
#86
I wonder if it's a result of intentional unilateral tolerancing. Ever notice how every car's speedo tends to be a little too optimistic? I have to think it's driven by liability concerns of the manufacturer which make them tolerance the speedo to over report speed rather than under report speed. Perhaps the gear ratios and therefore top speed of a gear at a given RPM is also slightly unilaterally toleranced to avoid exceeding the limit of the design envelope. Just an armchair conspiracy theory.
You can't really tolerance a gear -- count the teeth and that's the ratio.
I don't know how accurate GPS measured speed is, though.
--Ian
(edit): One other thought, if you're getting a few percent of tire slip, then that would account for some of it.
#87
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My data is from a 10hz antenna fed into a Racepak, then extrapolated to 20hz. More than accurate and repeatable enough to clearly show a discrepancy between "what is" and "what should be"
#88
This wont happen for another year or so...I am not in a huge hurry.
We are going to bolt the suspension/safety stuff together and he is going to spend the spring and summer doing HPDE, autoX and, spending the rest of his money on instruction.
The plan is to allow him time to establish solid control of the car before adding power. If that takes two years so be it.
I would also like him to get some wheel to wheel experience before the turbo, but that is still being discussed.
Once the turbo goes on the plan is to run it at lower boost until he connects with the power and feels good control over it. (one of the reasons I was talking about a dual port boost solenoid).
I suppose a smaller spring could be supplemented.
For those that asked?
I have a 580hp Sunbeam Tiger, and used to have a 740hp Cobra...Not to mention a host of scary fast longer wheelbase cars.
To me the 350hp Miata I drove was edgy and a sporty ride, but was completely predictable....A long way from the Tiger.
My son of course is not in the same boat....and there was no way he was going to drive that car.
See my above comments to Savington, but the plan is to work him into the power as slow as it required.
Eo2k,
If it was me I would have to know how much power I could make.
There has to be some curiosity there?
Thanks for all the comments as always!
Jamie
#95
For a while now, this forum has been reformatting urls so they do not link properly
https://forum.miata.net/vb/showthread.php?t=630740
https://forum.miata.net/vb/showthread.php?t=630740
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