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#41
Steve Scheifler

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Dave D. While no approach is perfect, by FAR the least imperfect basis for parity adjustments is a combination of calculator and competition between those at the very pointy end of the top events. That’s always assuming there aren’t any cheaters making one generation look stronger than it really is, thereby penalizing those playing by the rules. It’s not from any lack of concern for the rest of the field, it should be best for them as well. It’s just that any inclusion of results and feedback from a less consistent mix or car prep and driver can only muddy the picture. There’s just no avoiding it. The strength and depth at the front is actually one of the things that best serves the rest of the field when it comes to consistent POTENTIAL from all cars, and potential is what matters, not what people are doing with it in any given region.

Unfortunately the 1.6 is difficult because few top drivers run them, and all NA cars have a more difficult to quantify or compensate for issue with suspension geometry, but that’s another debate.
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#42
Cnj

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I'm thinking the price difference will be greater. I think a 35-40k Spec Miata is likely a 55-60k  Mx5 or will be VERY soon.  

 

Spec Mx5 will need the same competition level as Sm and some marquee players to switch. Mazda is combating that by throwing big contingency at it hoping it will entice some of the front runners in Sm and other classes to join in.  Personally I think the class is 5 years early and will eventually hurt SM, so while I am building one, I am not a huge supporter and don't really like the idea at this time.  I think it is early and may eventually hurt the best thing in racing.  What you said about the parity and different cars etc. If ANY significant changes are made in parity in SM, I fear people may do EXACTLY what you did, just build the spec Mx5.  There are minor differences in the years, some differences, but will be far far less than Sm.  

 

What people will find out quickly and not like much is these cars are more fragile than Sm and a minor front end collision will cost 4 to 5 x what it does in Sm. The bumpers, headlights, tail lights , hoods, fenders are very expensive. Throw in a $1200 radiator it will add up fast. 

Jim,

 

No doubt the Spec MX might drift up in price.  However I’m pretty confident that my statement about 30% more than a good SM is correct based on today’s prices.  Later this year or next?  Well that might be a different story.

 

And I don’t doubt that it’s more expensive to operate and to fix damage than my 99 has been.  On the other hand, I was considering buying a Spec Boxster and those operating and repair costs scared me straight back to Mazda land - and make the MX5 look cheap. Everything is relative.

 

Race cars and racing are the dumbest thing anyone can do with their money (or their kids inheritance).  I try to not justify my addiction, I just try to keep it under modest control. Or hide it :)

 

I surely hope that rules changes don’t rock the SM boat.  It’s a fantastic class and needs to stay so for a long time.  
 

CNJ


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#43
Tom Sager

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Let me preface this by saying I have a VVT, a 99 and I have access to an NA1.8 . I ran all three cars last year, doing back to back testing, specifically looking at what the weapon of choice would be for VIR. In the end I chose the VVT because it allows me faster recovery from my mistakes. But it wasn't the fastest car!! - OH yes and it also burst into flames!!!!!

 

With regard to the NA 1.8 vs 99 vs VVT I have personal experience from the same-day at both Daytona, Road Atlanta and VIR.

 

Last year, at Road Atlanta SARRC, I felt my '99 was a little off compared to the rest of the field on test day (was running 1:45's) so Mike Rossini loaned me his NA 1.8. It was the first time I had ever sat in his car, or in ANY NA1.8

Did one out lap, 2nd lap was under my '99 times, qualified on pole, and won the Sunday Race.

 

In August I took Rossini's NA1.8 to Daytona, and raced some of the fastest Daytona guys and won both races. Carter, Pardus, Gonzales, Collum, Davison and more and took the wins - honestly my car had the upper hand and it just ran on so much better at the top end without the limitations of the restrictor. 

 

Yes, I feel that the NA1.8, just like the '99, lacks the VVT grunt off the corner, but the NA1.8 has more than the '99 at the top and so much more than the VVT at the top.

 

From what I have personally seen on Rossini dyno runs (yes I know not all runs were done on the same day, but I have been privvy to data from hundreds of dyno runs over the years, so I have a pretty decent handle on the typical numbers shown on Rossini's dyno - so here are the typical great-to-unicorn numbers

 

NA1.8    130HP - 120TQ  (250 combined)

NB 99    129HP - 120TQ (149 combined)

NB VVT 126HP - 124TQ  (250 combined)

 

Once again, these are not numbers run on same day, and your numbers might vary depending on so many other factors, but I feel very comfortable with this characterization. Hope this helps for others trying to make the decision

Great post and certainly very credible coming from you.  Those tracks Daytona and Road Atlanta for sure offer long runs at higher RPM with the wheel straight.  Good fit for an NA1.8.  When your VVT burned up that was your chance to make the switch :).  

 

When I tested mine in both rules configurations at Blackhawk, I so desperately wanted the car to be faster with the extra power and extra weight.  It simply wasn't and I made a thorough honest effort.  In this part of the country (Northern Conference) the tracks (5 of them) are characteristically very different than Daytona and Road Atlanta, even Road America has more time on throttle under 6K RPM than above.  As mentioned the suspension IMO is the larger deficit (although not a large deficit).  Looking around the country it appears there are more "torque tracks" where the steering wheel is often not straight than "peak HP tracks". 


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#44
Tom Sager

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I generally agree with you and MPR that Spec MX5 will grow significantly, but not be a real threat to SM car counts for 2-3 years (ie steal significant crossover drivers).  Given the opening up of historic race groups to SM, it’s likely that there will be a lot of SM’s on track for a long time.  Just not necessarily in SCCA or NASA.
 

This time line accelerates if some of the top drivers begin to campaign Spec MX5 as they are only (currently) about 15% more expensive than a top flight SM build, but of course probably 50% more expensive than a budget SM build.  We will know more by next year about car count.  For sure this build cost is going to be more than most in SM are willing to pay - and playing in the Challenge series is not cheap either.  So some of the driver market will come from other classes.  
 

2 weeks ago I ordered a Spec MX5.  Lots appealing to me, not least that it’s so tightly specified that there will be (?) no bitching about different years - which we have been doing on this site for as long as I remember.  And my guess is that it will be fun to drive.  Fun is fungible and I don’t want to wait 2-3 years.  I’ll still play periodically in SM.

 

Regarding the NA6 and NA8, I (along with others) argued for them to get the better NB front suspension years ago and that was (foolishly in my opinion) shot down by a very vocal group of NA owners.  I found myself subsequently getting quickly bored about parity debates from the same crowd who always somehow wanted to castrate my 99 in power or weight rather than make simple and genuine parity improvements to their cars. While I have sparred from time to time with Bench, his tenacity on changing the NA cooling was good for the class and a simple move.  They should have, and still could adopt the improved suspension.  But I doubt SMAC will bring that one to the table again.  Once bitten.....

 

CNJ

Good luck in Spec MX-5.  the SM community will be watching how it goes.  I too felt a rule change to allow the NA cars to optionally install the NB front suspension was a no brainer and that for me would end this debate once and for all. 


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#45
Alberto

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Good luck in Spec MX-5.  the SM community will be watching how it goes.  I too felt a rule change to allow the NA cars to optionally install the NB front suspension was a no brainer and that for me would end this debate once and for all. 

 

Myself and others were against it at the time.  I, for one, was dumb and didn't understand the ramifications.  There was a bigger difference on parts costs for subframes and such back then too.


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#46
Jonathan Davis

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In terms of fast NA1.8's that I have seen in the SE and NE recently - and these are just my observations and opinions

 

1. Evan Karls previous car NA1.8- VERY Fast,

2. Conrad Kzaczyks current NA 1.8 - VERY fast and faster than most on long straights - Competitive at front of current HST races

3. Marc Cefalo's NA1.8 - very competitive - Competitive at front of current HST races

4. Mike Rossini's NA1.8 - VERY fast, especially on longer straights - Competitive at front of current HST races

 

have not seen a fast NA1.6 being campaigned by a front runner in some time 

 

As a point of reference, my 1.6 was equal to Cefalo's NA1.8 at the Mid-Ohio vintage race last year. Granted Mid-Ohio isn't a horsepower track and SVRA isn't the same as a Super Tour, but I don't think either of us were taking it easy either.

 

I tried to figure out a way to make a Spec MX-5 build work for me, but even doing everything except a cage myself, it looks like a bare minimum of $25k just to get it on track. Probably more like $30k in the end. As much as I would like to take a shot at the Challenge series, I'm not prepared to sell my SMs to fund a build for an unknown class at this point, so I'm taking a wait and see attitude this year...


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#47
38bfast

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To change the bump steer on a NA you can just space up the rack. Would be much cheaper and easier than replacing a subframe. two aluminum blocks with 2 holes each and 4 longer bolts. Just saying. 


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#48
Tom Sager

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To change the bump steer on a NA you can just space up the rack. Would be much cheaper and easier than replacing a subframe. two aluminum blocks with 2 holes each and 4 longer bolts. Just saying. 

I believe previous committees have taken this up and said no.  NASA made this a rule.  Does seem like a simple modification and an equally simple rule to have changed. 


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#49
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I believe previous committees have taken this up and said no.  NASA made this a rule.  Does seem like a simple modification and an equally simple rule to have change

I have never seen a letter on it. But it would have to be backed up with a swing the bump steer of a NB vs a swing with the NA and spec all the parts needed. Send in a letter. 


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#50
Ron Alan

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I believe previous committees have taken this up and said no.  NASA made this a rule.  Does seem like a simple modification and an equally simple rule to have changed. 

Funny how things come around when it comes to slight differences between the rules(SCCA/NASA)...the bump steer spacers seems to be a lone hold out. SCCA adopted the ELBJ while NASA adopted the rear upright rule in recent changes.

My guess is the reason for this thread(slotted rear upper control arm hole)will be adopted by NASA!

 

Tires obviously is its own agenda...


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#51
Steve Scheifler

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Bump steer is only one difference in NA/NB geometry and probably not the most important one.
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#52
Cnj

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Bump steer is only one difference in NA/NB geometry and probably not the most important one.

Interesting.  So what’s the most important difference in NA/NB geometry?  Not challenging.  Just curious.  

 

CNJ


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#53
Steve Scheifler

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Note that I said probably. But a change to the vertical location of any control arm results in a change to the instant center which in turn alters the roll center and roll axis. And a change in the roll center, among other things, impacts the effective leverage on the springs which is to say their effective rate, how much the car leans and how it rotates.

I haven’t looked for all the relevant measurements or attempted to take them myself because it’s a PIA and there is no point in it, we have what we have, but when the control arms are angled the wrong way at rest (inboard lower than outboard) you are starting with a roll center well below ground on a car not designed for that. For the NB several of the control arm mounting points were moved for improved geometry, so given that the arms themselves are dimensionally the same, the NB has different geometry at a given ride height, and as noted above that impacts pretty much all aspects of handling.
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#54
Martinracing98

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when the control arms are angled the wrong way at rest (inboard lower than outboard) you are starting with a roll center well below ground on a car not designed for that

 

When the outside of the control arms are closer together than inside the roll center is below ground. When outside of the control arms are further apart it is above ground. At least that is what I understand from Fred Puhn's book on car handling. Also a more steeply angled upper control(low inside) or shorter upper arms results in more camber gain during automobile lean. 

 

I do not know what the differences are, but a small change can make a big difference at the limit



#55
Tom Sager

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Steve thanks for the good explanation above.

 

So the bottom line is the NA1.8 at 2400 pounds is the worst handling car of them all.  The 1.6 is hampered by the same poorer geometry but the 125 pounds lighter weight provides some compensation for that in the corners.    That's not an argument for the NA1.8 to be 125 pounds lighter as it doesn't have the power deficit of the 1.6.,  It's kind of a no brainer that the NA1.8 with very similar per lap power compared to a '99 should compete just a smidge lighter than a '99.


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#56
Steve Scheifler

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When the outside of the control arms are closer together than inside the roll center is below ground. When outside of the control arms are further apart it is above ground.


That may prove generally true in practice with typical suspensions but I don’t think it’s absolute, particularly when lowering a car to the point that the inner pivot points are well below the outer. In that case the instantaneous centers are already below ground so the roll center must be as well. At least I can’t visualize a scenario where it isn’t. Once you have a scale drawing it is easy to get with a ruler and pencil in seconds..
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#57
Danny Steyn

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Great post and certainly very credible coming from you.  Those tracks Daytona and Road Atlanta for sure offer long runs at higher RPM with the wheel straight.  Good fit for an NA1.8.  When your VVT burned up that was your chance to make the switch :).  

 

When I tested mine in both rules configurations at Blackhawk, I so desperately wanted the car to be faster with the extra power and extra weight.  It simply wasn't and I made a thorough honest effort.  In this part of the country (Northern Conference) the tracks (5 of them) are characteristically very different than Daytona and Road Atlanta, even Road America has more time on throttle under 6K RPM than above.  As mentioned the suspension IMO is the larger deficit (although not a large deficit).  Looking around the country it appears there are more "torque tracks" where the steering wheel is often not straight than "peak HP tracks". 

 

If you come at it from the perspective of running fast times on your own, then yes, there are more where TQ is needed. However, most of the time we are not racing alone, we are racing in a pack getting drafted and pushed. In those situations the equation moves from being about the TQ out the corner, to the HP you have on hand in the passing opportunities, and then the equation really evens out. Which is why several will build '99's and possibly even NA1.8's for Road America, where we have 3, Count them, Three LONG 5th gear straights, (longer than VIR).

 

What do you have available coming into T5, coming down to Canada Corner and what do you have coming to the finish line???


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#58
Steve Scheifler

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One could argue that in pack racing a little torque is always important. Besides mistake recovery you eluded to earlier, if the guy ahead checks you up a bit on entry, or you need to take a less optimal line while attacking or defending, then it’s torque that makes or breaks the successful pass. Our cars have so little acceleration on long straights that if you can hang on or get close coming out of the corner then the draft will keep you there even if you are short a few HP. A few HP makes almost no difference in terminal velocity but a few ft lbs counts out of every corner. However, I don’t disagree that a few HP helps complete a pass on long straights, since you are in the draft it’s worth a lot more than at the same speed on your own and can be just enough to get the necessary run. All to often though I see people fail to leave enough gap out of the prior corner to build that momentum. But that’s another topic. My point is that a little extra midrange torque is useful many times every lap.
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#59
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One could argue that in pack racing a little torque is always important. Besides mistake recovery you eluded to earlier, if the guy ahead checks you up a bit on entry, or you need to take a less optimal line while attacking or defending, then it’s torque that makes or breaks the successful pass. Our cars have so little acceleration on long straights that if you can hang on or get close coming out of the corner then the draft will keep you there even if you are short a few HP. A few HP makes almost no difference in terminal velocity but a few ft lbs counts out of every corner. However, I don’t disagree that a few HP helps complete a pass on long straights, since you are in the draft it’s worth a lot more than at the same speed on your own and can be just enough to get the necessary run. All to often though I see people fail to leave enough gap out of the prior corner to build that momentum. But that’s another topic. My point is that a little extra midrange torque is useful many times every lap.

 

Yes Steve, TQ is always helpful, ALWAYS, but the more restricted VVT motor flattens out with terminal velocity before the 99 and WAY before the NA1.8. You can really see this on the rovals, where a strong NA1.8 can actually drive around two VVT's working together. 


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#60
Steve Scheifler

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Yes Steve, TQ is always helpful, ALWAYS, but the more restricted VVT motor flattens out with terminal velocity before the 99 and WAY before the NA1.8. You can really see this on the rovals, where a strong NA1.8 can actually drive around two VVT's working together.


I’d have to see the video, data and dyno curves to have any hope of explaining that convincingly, but if you are saying that’s true in 5th gear then there is definitely more involved than, what HP advantage?
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