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DeadSkunk
DeadSkunk HalfDork
5/28/11 3:11 p.m.

In the Readers' Rides there are about 8 bazillion Miatas. How low has anyone managed to get the weight on a street driven one? I know I've seen lightened ones dedicated to autocross (the blue one with the aluminum door skins comes to mind), but I'm wondering if it's possible to build one under a ton and still be drivable on the street. I'm thinking ditching heater/AC, carpeting ,soft top,side window,door cards etc. and adding bed liner on the floor,aftermarket seats.....like that.

mike
mike Reader
5/28/11 3:42 p.m.

Someday I will do this to my '94, if the engine keeps going (150K miles so far). I'll have to leave the heater in, though, for winter driving.

MrJoshua
MrJoshua SuperDork
5/28/11 4:37 p.m.

My '08 and '10 challenge car was 1880lbs weighed by the GRM crew at the challenge.
-1991 1.6 with turbo, front mount intercooler, and megasquirt -Poly motor mounts and no "motor mount cups"
-Running 13x8 diamonds with 225/45 hoosiers
-Motorcycle shocks in rear
-Illuminas with motorcycle springs in front
-stock driver and passenger seat w/seatback foam insert removed on driver seat
-Using Keith Tanner 1/2 dash with one of the radio supports removed
-Harbor Freight Driving Lights in flash to pass holes
-removed top, windows and regulators, carpet, ac, quarter windows, headlight buckets, front bumper plastic support, all interior

I left the interior door metal and didn't have a roll bar.

Edit-still has the "sharks teeth" or baby teeth or whatever people call them

DeadSkunk
DeadSkunk HalfDork
5/28/11 5:50 p.m.

Mr Joshua,
Did you need to change to motorcycle shocks and springs because it was so light, or was that what you could find to meet budget? How would that car have worked on the street? I'm just thinking that a stripped Miata would offer a bit of the experience of driving a locost without having to do all the fabricating. Do it the Colin Chapman way by adding lightness,although the turbo probably made it pretty entertaining !!

modernbeat
modernbeat Dork
5/28/11 6:22 p.m.

My STS2 legal '91 was as light as 1978 lbs. I still had the motor mount cups and a few other items that could have shaved some more, but the rules were grey on some of the things back then.

MrJoshua
MrJoshua SuperDork
5/28/11 6:42 p.m.
DeadSkunk wrote: Mr Joshua, Did you need to change to motorcycle shocks and springs because it was so light, or was that what you could find to meet budget? How would that car have worked on the street? I'm just thinking that a stripped Miata would offer a bit of the experience of driving a locost without having to do all the fabricating. Do it the Colin Chapman way by adding lightness,although the turbo probably made it pretty entertaining !!

The shocks were a cheap way to get a high spring rate. It would be stiff on the street, very lightweight though. Edited my original post to include poly motor mounts without the "motor mount cups" modernbeat mentioned.

MrJoshua
MrJoshua SuperDork
5/28/11 6:45 p.m.

It would be fun to see what someone could get one to with all the things I have done plus removing the windshield, interior door skins, converting to a tubular front subframe and running a NA rotary with a two barrel throttle body. I would probably want a basic low front hoop cage at that point though.

racerfink
racerfink HalfDork
5/28/11 7:42 p.m.

My '90 Spec Miata weighs 2275 with driver, and I'm 180lbs. I have a 35lb weight in the floorboard to meet that minimum. The rules are pretty restrictive in SM, so I have no doubt you could easily get under 2k with one.

dyintorace
dyintorace SuperDork
5/28/11 7:47 p.m.
MrJoshua wrote: It would be fun to see what someone could get one to with all the things I have done plus removing the windshield, interior door skins, converting to a tubular front subframe and running a NA rotary with a two barrel throttle body. I would probably want a basic low front hoop cage at that point though.

Someone should do all that with the car you have, except for the rotary swap and just get the existing turbo'd motor running correctly. I imagine they'd do quite well at the Challenge!

MrJoshua
MrJoshua SuperDork
5/28/11 8:00 p.m.
dyintorace wrote:
MrJoshua wrote: It would be fun to see what someone could get one to with all the things I have done plus removing the windshield, interior door skins, converting to a tubular front subframe and running a NA rotary with a two barrel throttle body. I would probably want a basic low front hoop cage at that point though.

Someone should do all that with the car you have, except for the rotary swap and just get the existing turbo'd motor running correctly. I imagine they'd do quite well at the Challenge!

Wheres the fun in fully finishing a car?

DeadSkunk
DeadSkunk HalfDork
5/28/11 8:27 p.m.

Do you think a 1700 lb. car would be possible if you were to remove the windshield,no passenger seat (maybe an aluminum tonneau), tubular front sub-frame, and no turbo, but stick with the piston engine? Other stuff would have to include the lightest tire/wheel combo,light seat,even remove extra wiring from the harness,a light exhaust system. Did your Challenge car have air bags and sensors removed, for example? I'm sure I've seen carbonfiber doors and trunk someplace, but that would add significant cost. I'd like to do as much as possible on a minimal budget and just remove all the weight I could.

Keith
Keith SuperDork
5/29/11 12:22 a.m.

A popular question - and the problem is defining "streetable". The Targa Miata, for example, is weathertight and has wipers, which makes it more streetable than some others I've driven. But it's fully stripped inside, which makes it less so. It's right around 2100 with a full cage, by the way. It could be lighter if it wasn't armored underneath, but then it would be wrong for it's job

Take any weight claims with a grain of salt. They're prone to exaggeration just like horsepower numbers. I always quote numbers with the car full of all fluids, because that and fully drained are the only two repeatable conditions.

Kendall_Jones
Kendall_Jones Reader
5/29/11 1:24 a.m.

the scca f prod (john b @ whrri) cars are 2075 with driver. totally not agreeable (unless your hard core) - fiberglass body, no windscreen, most run ballast though. :)

Kendall

MrJoshua
MrJoshua SuperDork
5/29/11 6:44 a.m.
Keith wrote: A popular question - and the problem is defining "streetable". The Targa Miata, for example, is weathertight and has wipers, which makes it more streetable than some others I've driven. But it's fully stripped inside, which makes it less so. It's right around 2100 with a full cage, by the way. It could be lighter if it wasn't armored underneath, but then it would be wrong for it's job Take any weight claims with a grain of salt. They're prone to exaggeration just like horsepower numbers. I always quote numbers with the car full of all fluids, because that and fully drained are the only two repeatable conditions.

My weight was done by the GRM crew at the challenge. I drove it onto the scales, after driving it to the concours portion of the challenge, after competing in the autocross. I don't think you were specifically calling me out, but I wanted everyone reading to be confident I obtained my numbers through a reliable method. My numbers are published in this years challenge issue. The car placed 22nd.

DeadSkunk
DeadSkunk HalfDork
5/29/11 6:55 a.m.

Kendall, yes it would be hardcore,as you say, but it shouldn't be any worse than a locost. If John's car weighs in at 2075 with him in it, then the car must be around 1875, and that's with a cage. No idea if he has to run any ballast. With cars now available for $2K ,and less, it's getting to the point that I would consider buying one just to strip it out and see. It could be a "nice day" back road carver, or a track rat.Then, if it were too hardcore to enjoy I'd be finding a way to weld on a roof and create the Miata GT I keep dreaming of !

Keith
Keith SuperDork
5/29/11 10:06 a.m.

I wasn't calling anyone out on weight number, it's just something I've seen over the years. There seems to be a high fudge factor in weight estimates in general - parts going on tend to be carefully weighed, parts coming off are estimated. And the fuel load is always monkeyed with.

I'm not going to make any estimates on the minimum weight, as I've been surprised (in both directions) too many times in the past. I do think that 2000 lbs is a good target for a streetable and weathertight car that's a achievable without a big expense but a fair bit of effort. Going less than that involves a fair number of compromises.

DeadSkunk
DeadSkunk HalfDork
5/29/11 10:13 a.m.

One of the folks from Aim Tuning (??) was at Waterford Hills a few years ago with a stripped Miata. Weight was stated as "less than a ton", and it was turboed. The fellow drove it from Indianapolis to Waterford without any top or carpeting.Reputedly developed 300 HP. It must have been fun !

Tom Heath
Tom Heath Web Manager
5/29/11 1:03 p.m.

According to the scales at Solo Nationals, my car weighs 2370 with a half tank of gas. That's with A/C, full interior, stereo, speakers, etc.

I've done almost nothing in terms of weight reduction other than remove the spare tire and jack.

dyintorace
dyintorace SuperDork
5/29/11 5:45 p.m.
MrJoshua wrote:
dyintorace wrote:
MrJoshua wrote: It would be fun to see what someone could get one to with all the things I have done plus removing the windshield, interior door skins, converting to a tubular front subframe and running a NA rotary with a two barrel throttle body. I would probably want a basic low front hoop cage at that point though.

Someone should do all that with the car you have, except for the rotary swap and just get the existing turbo'd motor running correctly. I imagine they'd do quite well at the Challenge!

Wheres the fun in fully finishing a car?

Sadly, we may never know.

modernbeat
modernbeat Dork
5/29/11 5:59 p.m.

My car was weighed at home on my Longacre scales and weighed again a few times at National level Solo events. There was no weight taken off for fuel load. It was weighed with a very small amount of fuel in it.

MrJoshua
MrJoshua SuperDork
5/29/11 6:23 p.m.

In reply to dyintorace:

I was going to be insulted, and then I remembered it was true. (and that you are picking on yourself as much as me )

mad_machine
mad_machine SuperDork
5/29/11 6:29 p.m.

I don;t see where people say a lightweight Miata would be hard to live with. It was only a couple of decades ago what sports cars crested the ton.. and wasn't one of the MR2s under 2000 pounds?

alfadriver
alfadriver SuperDork
5/29/11 7:25 p.m.

Keith Got any old Miata mags? a LONG time ago, there was an article about how to make a light weight one. Not sure how accurate it was, though. May have to see if I can find the copy that I think I kept.

I've thought about it, too. And still think a Miata should be able to win, even with 4 cyl. Just don't have the gumption to do it.

MrJoshua
MrJoshua SuperDork
5/29/11 7:43 p.m.

In reply to alfadriver:

A Miata with 275/35/15 hoosiers, somewhere around a 700/500 spring rate with shocks to handle it, limited slip, thoroughly gutted, drag slicks, a good graphics package, and at least a 100 shot with maybe another 100 to use only on the top end of the track, should be an easy winner. Its about as simple of a winning challenge package as exists.

fastmiata
fastmiata HalfDork
5/29/11 7:51 p.m.

Start with a '89 early build car and you can get quite low. I dont remember the number anymore but my first SpecMiata was a May '89 car and needed quite a bit of ballast to make weight. The second SM started life as '92 Package B and we could never get it near the same weight. Both were under the class minimum but the lighter weight allowed for creative ballast.

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