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Lightest RX-7 Race car weight ?(exclue Tube frame)

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Lightest RX-7 Race car weight ?(exclue Tube frame)

Old 02-19-06, 03:20 AM
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Lightest RX-7 Race car weight ?(exclue Tube frame)

As some peopel may know it. I have SCCA ITE FC3S. Basicly the ITE rule is very loose , so do the weight regulation... But one thing really bother me . My FC seen to be always on heavey side. My FC weight 2240 with out driver and with 10 gal of gas. I done all the typical SCCA race car will do, under regulation no LEXAN windshielf did not cut off any sheet metal yet. From what I understand, Tri point's FP or BP FC3S weight 1900 LB. and my Friend Steve's BP FC3s also weight under 2000LB. mabe in solo2 they dont need to use very thick roll cage.. just wonder what is lightest possible you see on the UNI body FC... or any RX-7

However inorder to my car a bit faster in Time attack and race, I am plan to cut some of sheet metal in my car... so I am thinking where should I start first. the big U shape bar behind the seat seen to be a good place to start... however my roll bar's main hoop is also weld on top of that dam . My door is not complete cut, I cut of bar and some skin. wonder how much weight I can save from there..
I already have 91 alu hood and lexan hatch... it save some weight there. but my car also had a lot of weight back due to my AERO mod... ( front bumper spoiler. wide fender. side skirt, GT wing) and my big wheel. I tend to run 18x9.5 wheel on my FC....

I plan to loose weight? to like 2180. wonder is this possible....

Thanks for reply

J
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Old 02-19-06, 07:31 AM
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I am not familiar with the FC, only the FB. However, when you compare your car to the BP / FP solo cars, you have to realize they are totally prepped race cars. They likely have no lights, have fiberglass bumpers, were taken to bare shells before building, etc. They have only the components they absolutely need. I have not seen the current TriPoint car but have seen some of their older cars - they are built like pure race cars.

I assume that since your car is ITE that it still sports a lot of the stock based components. Things like wiring harnesses and dashboards and pedal assemblies add up.

Assuming the ITE rules you follow are similar to the general IT rules, you might be able to save weight with a creative interpretation of the "retain the stock dashboard" rule. I have seen a couple make it through protest that I didn't think would.
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Old 02-19-06, 08:00 AM
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The Solo 2 cars are very light, because they don't have the heavy cage, heavy brakes, and heavy cooling system requirements of road racing. They only have to run for 1 minute at a time.

It gets more and more expensive to remove weight off my race car. The first bit was easy and cheap, now it is extremely expensive ($50/pound) to pull each additional pound off. Thin sheet metal does not weigh much. A lot of my SA-22 1st gen chassis is made from 1mm thick steel sheet, which only weighs 1.04 pounds per square foot. Use a micrometer to measure the thickness of what you are thinking of cutting out, and get an estimate of how many pounds it will save. A Zizz wheel (cutoff wheel) is good for cutting in tight places you can't get a Sawzall blade in.

It will be much harder to cut that extra weight out now that the cage is in place. Removing weight anywhere is good, but you will see even more performance if you can remove weight high up in the chassis (like glass and roof and dash board) or weight that is forward of the front wheels or aft of the back wheels.
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Old 02-19-06, 09:12 AM
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12.5 lbs for each door bar, do the drivers side ONLY if you have a good cage. You could get an fiberglass hood that will weigh about 15 lbs, save that aluminum one for a street car. I would really think twice before cutting anything out of the car that is part of the unibody unless you have done an extensive cage in the car. More than just a 6 or 8 point cage.
The metal frame for the hatch weighs 17 pounds and most of it is up on top by the hinges. If that's your car in your avatar I can't tell if you still have all of the headlight junk still, there is a few pounds there.
The stock alternator wieghs 11lbs, find a smaller one or go to a total loss system.
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Old 02-19-06, 09:56 PM
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"The Solo 2 cars are very light, because they don't have the heavy cage, heavy brakes, and heavy cooling system requirements of road racing. They only have to run for 1 minute at a time."

Good point - forgot about that one! I remember a well prepped BSP Camaro or Firebird that shaved a ton of weight by using suspension and cooling components from a 4 cylinder F-Body car.
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Old 02-20-06, 01:42 AM
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Thanks for the info. For now, I might want to cut the door more complete... and mabe in spring-summer. I will change to compost Fender.... and by running smaller wheel will save a lot of unsprung weight !!! MY Exhaust system is kind da heavey too. RB header, Y pipe. and 3 inch steel pipe and LAVA rock muffler. I wonder they are market for more improve LAVA Rock muffler. because From my home country , It is not too $$$ to make custom muffer. told them the spec you want and they can make it. I am thinking mabe I should make one more oval shape and wider . so it can fit under floor .

Had any one cut their roof off. replace with ALU ? or compost part?
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Old 02-20-06, 03:06 AM
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You could, but I don't see how you would reattach the roof. Also, the roof is the most pivotal structure in a unibody chassis, being that that is where all the flex is sent through.
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Old 02-20-06, 03:44 AM
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Why bother putting a roof back on at all? It's ITE, very loose rules, make it a convertible! That'll save a lot of weight up top, where it hurts handling most. You could then re-do the roll cage to minimize the weight up top (like an EP miata, with the rollbar at full height only right over your head), and to regain some of the strength lost from the roof removal.

You could put the muffler under the passenger floor and have it exit the side to save weight.

Composites are your freind, so is aluminum, replace all the steel you can with them.

I've seen miata hoods with the headlight doors moulded in. That enables 100% of the headlight assemblies to be removed. A CF or fiberglass honeycomb hood in this style probably would save much weight.

You can replace the passenger door with a fiberglass or aluminum skin that's permanently fixed to the chassis to save more weight.

Just some thoughts.
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Old 02-20-06, 11:36 AM
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I would not cut the crossmember out from behind the seats.
You can cut a lot out of the door though. I've cut the interior handle off since this picture was taken. And a little more can be cut around the perimeter.
Good luck
Attached Thumbnails Lightest  RX-7 Race car weight ?(exclue Tube frame)-gutted_door_sm.jpg  
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Old 02-20-06, 12:28 PM
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-all aluminum coilovers from silkroad or zeal to shed some weight
-superlight fiberglass hood skin, dont even bother with one that has hinges, run 4 hoodpins and be done with it, probably save you 20 pounds.
-gut the doors completely, leaving only the lock mechanism.
-gut the interior as much as possible, drill holes in any pieces that remain.
-autocrossers typically run 15x10 or 16x10/12 superlight aluminum wheels, you can too, there are 275 wide Rcomps from many mfg'ers in 16" and you can find 16x10 aluminum wheels from RealRacing that might weigh something like 8 pounds less than each of your current wheels, thats almost 40 pounds for wheels alone.
-crossdrilled rotors and remove the parking brake mechanicals.
-super lightweight exhaust piping, the thinnest stuff you can find and most racecars have a dump or turndown halfway back, they probably run half the pipe length that you run.
-fuel cell, didya put one in yet, I forget? it also allows you to remove the fuel filler neck, right?
-aluminum or fiberglass roof panel if you want to get all trick.
-lexan side windows if you need anything at all... remove the crank mechanicals.

a 2000 pound FC must be amazingly nimble.
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Old 03-07-06, 04:07 PM
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I dont understand why any racecar would have the headlights still in. take the full assemblies out, cut them from the pop-up cover skins, and remount those with some aluminum brackets. In a Unit body car I wouldnt cut out anything integral to the frame, or anything inside the car for that matter, but fore and aft the strut towers is pretty much game.

just as your friend to take a look at his car and compare what he did that you didnt.
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Old 03-08-06, 05:31 PM
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ITE AKA: Improve Touring "EVRYTHING"
I dont recall a weight standered in this cause it a class where everything runs.I used to run it with Haltech and spoiler, 13B monsta port.
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Old 03-09-06, 09:03 AM
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Originally Posted by designfreak
I dont understand why any racecar would have the headlights still in.
They're required in many of the classes (IT except for ITE, Touring, Showroom Stock, etc.) Also they really help if you are planning on running an Enduro or other night driving ;-)

-b
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Old 03-16-06, 12:12 PM
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any ideas or progress?!??!?!?

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Old 03-17-06, 07:48 AM
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My FC EP car just weighed in at 1923lbs dry, without me in it. So with oil, coolant and a few other odds and ends I expect it to come in under 1975lbs.
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Old 03-17-06, 10:25 AM
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thats amazingly light!
any pics or a modlist?

wow... sub-2000 pound FC... I just pissed my pants!
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Old 03-17-06, 10:35 AM
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I started a thread with the car called 'An EProd car is born' with a bunch of pics and other info. I put a link here for you if I knew how, just scroll down the Racing section, you'll find it.
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Old 03-17-06, 11:28 AM
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That's about where mine was maybe a bit heavier but I had more cage then yours. BTW mine is still for sale...
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