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Learning how to build Lotus Seven replicas...together!
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PostPosted: Tue Feb 10, 2009 2:06 am 
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Decided to start yet another thread to see who's building for ST and where you're located.
Instead of coming up with a new formula here a nationally competitive class that the locost fits into and everyone can build to the same adjusted final power to weight ratio while having fun figuring out their own weapon.

I'm building for ST2, ST1 is too expensive and SU is totally out of reach.

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PostPosted: Tue Feb 10, 2009 8:04 am 
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The NASA ST rules are here: http://www.nasaproracing.com/rules/Super-Touring.pdf
The overall club rules are here: http://www.nasaproracing.com/rules/ccr.pdf

Worth noting is that the ST rules already have the following provisions:
Quote:
Brunton Stalker (If aero mods, wing, or splitter, then -0.75 modification factor)
Brunton Stalker (If no aero mods, wing, or splitter, +0.75 modification factor)
Caterham & Lotus 7 (if aero mods, wing, or splitter, then -0.75 modification factor)
Caterham & Lotus 7 (if no aero mods, wing, or splitter, then +0.75 modification factor)

Having a traditional locost classed based on the cars above should be fairly simple. It should also be possible to have a middie classed for ST based on power to weight with appropriate modification factors.

The heart of the class spec is:
Quote:
Super Touring 1 (ST1) = “adjusted” wt/hp ratio equal to, or greater than, 5.50:1
Super Touring 2 (ST2) = “adjusted” wt/hp ratio equal to, or greater than, 8.70:1

The modification factors are:
Quote:
The “modification factor” listed after each item below is added or subtracted from the actual
measured wt/hp ratio to determine the “adjusted” wt./hp ratio that determines vehicle legality in
each ST class.

Body Type: 4-door Sedan or 5-door Wagon = +0.4
Transmission: Dog-ring/Straight-cut gears (non-synchromesh) = -0.2
Sequential/Tiptronic-like/paddle shift/semi-automatic = -0.2
Drivetrain: AWD = -0.5, FWD = +1.0

Tires: Non-DOT approved tires = -0.75 (VRL & GAC Hoosiers see App. A)
Size 275 to 250 (or 10.5” to 9.6” for non-DOT approved) = +0.4
Size 245 or smaller (or less than 9.6” for non-DOT approved) = +0.8

Competition Weight: Modification factors for weight (with driver) are listed in the ST rules.

Based on the ST rules package a bike engine build weighing in at 1100 lbs with driver could be at or very near the ST2 cap with 138 whp. A car with more power or less weight would probably need ballast to stay within the ST2 spec. It's worth noting that up to 250 lbs of ballast is permitted.

So that's the direction I plan to take my build when it finally gets rolling. I plan to build my car as a replica of a late 60's closed prototype (think along the lines of a GT40 or 906/908) using bike based power.

I think it would be pretty easy to work entirely within the ST rules and still develop a locost sub-class. From this point if we can get enough competitors to build cars to a sub-spec we agree on then moving to a nationally recognized class should be a fairly small step. Even if our effort to develop an effective sub-spec fails, we would all still have cars that could be actively raced in NASA's ST classes.

Thoughts?

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PostPosted: Tue Feb 10, 2009 9:25 am 
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While at one point I wanted to see if I could make them change the modification factor for aero-7's or rewrite the openness of their aero rules, and I still think a full on aero-7 might be able to dominate with the unlimited aero mods available, unfortunately my build will initially end up in SU and I'll have to beg/plead/cry-like-a-little-girl to try to get it into ST. If I were building to be classified as an aero-7, I probably would have gone with a Ford Duratec 2.0/2.3 moderately tuned to ~167whp and aim/balast for 1501 lbs.

I also believe that NASA is currently developing a class/rule structure for tube frame cars, which I'm assuming is where a lot of the "ST approved" tube frame cars will ultimately end up. This may (or may not) end up being a very good class structure for those of us building cars that do not fit the description of a Lotus 7 replica.

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PostPosted: Tue Feb 10, 2009 8:21 pm 
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A bit more digging over at the NASA forums shows that they pretty much treat any seven clone by the Lotus, Caterham , Brunton rule listed above. That's good news for people wanting to run a traditional locost; the class and specific modification factor are already worked out.

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PostPosted: Tue Feb 10, 2009 9:07 pm 
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ST? Jesus lol

All we are planning is Time Trials and hillclimbs :D

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PostPosted: Wed Feb 11, 2009 12:03 am 
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217 Racing wrote:
ST? Jesus lol
All we are planning is Time Trials and hillclimbs :D

I don't know that I'll ever see wheel to wheel with my car or not (hell the only thing I'll certainly be competing in at this point is autox) but ST1/2 discussion is pretty much the same thing as TTS/U discussion in my book...So welcome aboard.

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PostPosted: Wed Feb 11, 2009 12:19 am 
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I find the NASA stuff slightly mystifying. And also some impression they just drive around and wave at each other, perhaps the occasional "Cheerio!". :whip: I just don't know.

So if you run a Seven, you either gain .75 or lose that amount depending on any aero mods? You can't be neutral, right? Also the weight chart doesn't go down to were a Seven would be, but they just extend for that or do you get a free ride for the extra couple hundred pounds you can get under the chart?

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PostPosted: Wed Feb 11, 2009 1:20 am 
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Remember that like all proper race cars, that weight is with driver too. Either way, if someone would give them a good reason to extend the weight factor chart (ie decimate the competition) I'm sure they would. The best part of open rule classes like this is being the reason that rules get created or changed. ;)

I actually think it's a surprisingly simple and elegant solution to running a wide variety of cars head to head. A 7-esque car can not be considered aerodynamically equivalent to a normal car, because it's really not. Other than that it's just like picking a class to build a car to the limit of in SCCA. Much like a Miata is either built to be a Spec Miata racer or a E-Production car, but there really is no in between. Either you appear as a Lotus 7 with no aero mods and are driving a lightweight brick with no significant ability to produce downforce, and get a power adjustment factor to help compensate...Or you vaguely resemble a Lotus 7 with substantially lower drag and/or the ability to produce prodigious amounts of downforce compared to any other car allowed in the class, but take a power factor hit to compensate the other way. Much like there is no point in running an E-Production Miata with a Spec Miata motor, there is no point to just doing "mild" aero mods to a 7-esque car if you want to build it to be competitive in this class structure.

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Last edited by Driven5 on Wed Feb 11, 2009 9:39 am, edited 1 time in total.

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PostPosted: Wed Feb 11, 2009 9:16 am 
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Thanks, Driven5. I'm guessing wouldn't be a good idea to show up with a wing like a World of Outlaws dirt track car though. Must resist....

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PostPosted: Wed Feb 11, 2009 9:27 am 
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If NASA had the same type of rule structure for lower speed autox type of events, I think that would be awesome to see!...If for no other reason than a good ol' case of "because I can". :twisted:

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PostPosted: Wed Feb 11, 2009 2:12 pm 
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Driven5 wrote:
there is no point to just doing "mild" aero mods to a 7-esque car if you want to build it to be competitive in this class structure.

Exactly.
Either you do what you can within the no-aero limit (some tiny stuff can be done, see here), or go all out with a full aero package a-la Donkervoort 'ring special.

Erioshi, your build plan is pretty much what I'm building, I think it'll make for a good competitive car.
I'm not sure how you're going to get to 1100 lbs with the driver in full race trim though (cage, fuel cell, fire sys etc..).

Moti

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PostPosted: Wed Feb 11, 2009 3:31 pm 
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I thought all tube chassis cars had to be in STU or higher?

Scratch that, thats only a rule in NASA Time Trial (what I'm building for). TTA-H are the "regular" classes, then theres TTU, TTS, and TTR. We get placed out of TTA-H because were not a "production car".
TTS uses the >= 8.7 lb/hp
TTU is >= 5.5 lb/hp

TTR is totally unlimited - no lower weight limit, no lb/hp limit.

I'm "designing" for TT rules


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PostPosted: Wed Feb 11, 2009 4:18 pm 
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The all or nothing aero approach has me wondering. I read the other thread and see they will allow a modest airdam and funny top front fenders. The funny top would probably help the rear fenders too.

So is it an aero mod if your rear fenders are bolted to the upright, like the fronts? Once in awhile you see that on a seven, I think even on the very early Lotus' (like the six?).

How about extending the belly pan up under the engine to the front of the car (worry about cooling later)?

Would a 1" rubber skirt along the bottom sides of the engine area be right out?

:BDH: That's a problem with being an engineer, your always trying to get around things...

Maybe STU is doable, once you get the big dirt track wing. It would be so worth it just to see people faces. The Seven roll cages just look like their begging for a little bit of fairing, with a thousand ponds of downforce...

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PostPosted: Thu Feb 12, 2009 11:53 pm 
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horizenjob wrote:
The all or nothing aero approach has me wondering. I read the other thread and see they will allow a modest airdam and funny top front fenders. The funny top would probably help the rear fenders too.

So is it an aero mod if your rear fenders are bolted to the upright, like the fronts? Once in awhile you see that on a seven, I think even on the very early Lotus' (like the six?).

How about extending the belly pan up under the engine to the front of the car (worry about cooling later)?

Would a 1" rubber skirt along the bottom sides of the engine area be right out?

:BDH: That's a problem with being an engineer, your always trying to get around things...

Maybe STU is doable, once you get the big dirt track wing. It would be so worth it just to see people faces. The Seven roll cages just look like their begging for a little bit of fairing, with a thousand ponds of downforce...

Yes but you better be bringing the power since as you well know downforce=drag. :) As for the rear cycle style fenders I know "butterart" used them, but I'm not sure how they were mounted.

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PostPosted: Fri Feb 13, 2009 12:48 am 
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To race in SU, you'll need to bring the horses regardless of downforce.
Good chance you'll find yourself racing against some 700 HP stock cars and such...

Moti

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