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Learning how to build Lotus Seven replicas...together!
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PostPosted: April 7, 2024, 9:04 pm 
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I spent some time this weekend turning some laps at a HPDE with my 986 S .
This got me thinking about building a Locost for track days.

I do not know what racing class their are for a car like this ?
So power is up in the air.

So I'm asking for ideas for a car like this.
Would like to keep the cost down. I know I'm dreaming about this.
What doner ? If their is one.
Front suspension ? Would you use something other than the Book ?
Rear Suspension ?
Motor/trans ?
Tire/Wheel's ?

My other build's are not a substitute for something like this.

Thanks.

:cheers:

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PostPosted: April 7, 2024, 9:12 pm 
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In my limited experience, HPDEs rarely have classifications, and if they do, it's for driver experience, not the type of car. For track use, a BEC (Bike-Engined Car) can be a lot of fun, great in the turns, but not so much on straightaways. There, expect to be trounced by just about everything due to the terrible aerodynamics of Locosts. You can still run, but a V8 may be necessary for pushing all the air out of the way. That said, no one "wins" at HPDEs, it's just for fun and doesn't require 600 hp. There's no trophy, as it's just to see how your car stacks up against others.

As far as keeping costs down, that's another reason to stay clear of big engines. The most popular setup is using Miata parts, engine, tranny, rear end, and wheel hubs. If you choose going your own way, then the sky is the limit both on design and expense. If you're considering something mid-engine, might I suggest my design book, in my signature :)

PS: I just noticed that you've been here a long time, and am surprised that you're asking. You did say trackday events, and not real SCCA-type racing, so yeah, it's pretty simple.

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PostPosted: April 7, 2024, 9:41 pm 
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KB58, thanks for the impute.

The racing will be NASA, Pro Auto Sport, maybe SCCA but their hard to work with.

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PostPosted: April 7, 2024, 9:42 pm 
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And yes I have your books. :mrgreen:

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PostPosted: April 8, 2024, 8:04 am 
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A quick read of the NASA rule book, it looks like you would be in the Super Touring class.

Non-Production” vehicles (ST1, ST2, and ST3 only), include all other ST series eligible vehicles including “kit” cars, purpose-built track/race cars, tube-frame and partial tube-frame conversion vehicles, and “Production” vehicles that have modifications not in compliance with section 6.2, and will be assessed the “Non-Production Vehicle” Modification Factor listed in 6.5.2 unless the vehicle model is listed in Section 6.5.3 of these rules and has been approved to compete under “Production” vehicle status. A competitor with a vehicle originally qualified as a “Production” model may use the Modification Factor assessment for “Non-Production Vehicle” to avoid all “Production vehicle only” limitations/restrictions in section 6.2.

Looks like a BHP/Weight formula

Super Touring 1 = Adjusted Wt/HP ratio equal to, or greater than, 6.00:1
Super Touring 2 = Adjusted Wt/HP ratio equal to, or greater than, 8.00:1
Super Touring 3 = Adjusted Wt/HP ratio equal to, or greater than, 10.00:1
Super Touring 4 = Adjusted Wt/HP ratio equal to, or greater than, 12.00:1
Super Touring 5 = Adjusted Wt/HP ratio equal to, or greater than, 14.50:1
Super Touring 6 = Adjusted Wt/HP ratio equal to, or greater than, 19.00:1

More at

https://members.drivenasa.com/rules


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PostPosted: April 8, 2024, 12:42 pm 
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Thanks ,FastG

:cheers:

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PostPosted: April 9, 2024, 9:27 am 
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I would go to some races and see what is actually being raced in each class. I think you will be in ST1,2,3. Adjusted Wt is car plus driver. You could build a 7 to meet any of those specs. But you would have to plan against the other cars in the class. Aerodynamics play a big part. You could build 7 for the fastest class but would give up a country mile on a long straight. Light, low power and nimble might be the answer. It's an interesting problem. I am interested to see your solution.

Graham


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PostPosted: April 9, 2024, 11:52 am 
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Good idea, Graham.

Next race is pretty far away, about 3.5 hours.
Then they take a brake for the hot time here.
So it will be something for the future.

:cheers:

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PostPosted: April 11, 2024, 7:45 pm 
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So much has to do with the tracks. Back in the day Team Birkinsport won NASA's Super Unlimited endurance class in the Western region against things like a twin-turbo Viper. At a big track like Willow Springs the HP cars would pull away, but at Sears Point and Laguna, the sprightly 250HP 7 would take it. One other thing that worked against the big cars were consumables. In a longer race, they'd be going through multiple sets of tires, whereas the 7 would go the full race without stopping with a big gas tank and tires that lasted the entire way through.


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PostPosted: April 12, 2024, 9:23 pm 
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Ford Kent 1600 Cross-Flow, of course.
Much lighter than an MGB engine, more power, more RPM, parts are inexpensive.
And they were actually original to some Sevens.

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PostPosted: April 15, 2024, 9:05 am 
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I found this ad in the back of Grassroots Motorsport for https://fastcraft.biz/ they are actively racing 7 type cars in NASA Super Touring classes. I am sure they would know the best class to position a 7 in.

Graham


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PostPosted: April 20, 2024, 5:17 pm 
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If you are looking for cheap track fun with some competition but lower risk than wheel to wheel, try Time Trials. It is basically like F1 qualifying as a sport. You get measured results and a chance at a trophy. SCCA has a very simple ruleset and cost of entry is relatively cheap. https://timetrials.scca.com/

Like others have said, stay small with reliable motor. Also think about expendables like tires and brakes. I choose to run 13" wheels so I can buy used formula car slicks with high performance capabilities. I can pick up a set of 4 tires for under $400 with 90% tread left! The tire when new are $400 each!!! They will get me through 3 weekends at least.

There are several Locost Sevens out there. Mine included.


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PostPosted: April 21, 2024, 4:48 pm 
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locofinn wrote:
If you are looking for cheap track fun with some competition but lower risk than wheel to wheel, try Time Trials. It is basically like F1 qualifying as a sport. You get measured results and a chance at a trophy. SCCA has a very simple ruleset and cost of entry is relatively cheap. https://timetrials.scca.com/

Like others have said, stay small with reliable motor. Also think about expendables like tires and brakes. I choose to run 13" wheels so I can buy used formula car slicks with high performance capabilities. I can pick up a set of 4 tires for under $400 with 90% tread left! The tire when new are $400 each!!! They will get me through 3 weekends at least.

There are several Locost Sevens out there. Mine included.


What are you running for tire size and wheels ?

:cheers:

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PostPosted: April 22, 2024, 7:09 am 
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Front: 13"x9" wheels with 13"x8.5" Goodyear radial slicks 21.5" dia.
Rear: 13"x11" wheels with 13"x11" Goodyear radial slicks 22.5" dia.

I run Real Racing Wheels from
https://www.rsracing.com/rrw13.aspx

These tires are are run on Formula cars like Formula Atlantic and P1 (prototype class) cars in in SCCA. They use them for qualifying then sell them cheap with more than 75% tread left. I get my tires from John Berget Racing Tires in WI. Last set I got last year were under $100 each tire shipped UPS to me in Indiana
https://www.jbracingtires.net/

Tires are the biggest expense if you run a lot of track events.

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Building a whole car from scratch is a 1,000 little tasks, done 1 task at a time, while thinking 10 tasks ahead, then redoing it anyway.
South Bend Region SCCA D-Modifed Class Autocross & Track-Day/TT. Chevrolet 1.4 L Turbo Ecotec Power


Link to my build log:
http://www.locostusa.com/forums/viewtopic.php?f=35&t=3356


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PostPosted: April 23, 2024, 1:28 am 
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locofinn wrote:
Front: 13"x9" wheels with 13"x8.5" Goodyear radial slicks 21.5" dia.
Rear: 13"x11" wheels with 13"x11" Goodyear radial slicks 22.5" dia.

I run Real Racing Wheels from
https://www.rsracing.com/rrw13.aspx

These tires are are run on Formula cars like Formula Atlantic and P1 (prototype class) cars in in SCCA. They use them for qualifying then sell them cheap with more than 75% tread left. I get my tires from John Berget Racing Tires in WI. Last set I got last year were under $100 each tire shipped UPS to me in Indiana
https://www.jbracingtires.net/

Tires are the biggest expense if you run a lot of track events.


Thanks.

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