Roof or no roof...weight v Aero.
#1
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I have been trying to buy a damaged race roof cheap from a supplier but he is out of town...was hoping to have it fitted and ready to race on Saturday....
Between the race weight roof and the new f/glass race weight boot lid I was hoping to drop a decent amount of weight and have a crack and my PB lap time.
Turns out neither the roof or boot will be ready and I suddenly thought had the brain wave... save even more weight and just take the whole bloody roof off.
Now I can't decide whether the Aero loss will be offset by the weight loss....
Anyone care to elaborate....?
track is approx 2.8km long with only one main straight that will have a top speed around `90 - 200 KPH.
Between the race weight roof and the new f/glass race weight boot lid I was hoping to drop a decent amount of weight and have a crack and my PB lap time.
Turns out neither the roof or boot will be ready and I suddenly thought had the brain wave... save even more weight and just take the whole bloody roof off.
Now I can't decide whether the Aero loss will be offset by the weight loss....
Anyone care to elaborate....?
track is approx 2.8km long with only one main straight that will have a top speed around `90 - 200 KPH.
#12
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Edit - Looking at it he obviously used either carbon fiber or glass that he had laying around. Not coroplast. Similar idea.
(sorry for potato quality, only shot I could find)
![](https://www.miataturbo.net/attachments/race-prep-75/161974-roof-no-roof-weight-v-aero-ayoqxh8.jpg?dateline=1455135907)
Last edited by dasting; 02-10-2016 at 03:36 PM.
#13
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This is where virtual dyno is really cool. Make a 4th gear pull with the top and without the top, don't correct for the weight difference, and it'll give you an answer which is faster for any given speed.
I logged a couple pulls a long time ago in a NA8 with headlights up vs down and the areo difference showed up pretty big above 40mph.
I feel like you could pretty near pinpoint the speed where your areo advantage overtook the weight advantage and it'd give you a clearcut answer to your question.
I logged a couple pulls a long time ago in a NA8 with headlights up vs down and the areo difference showed up pretty big above 40mph.
I feel like you could pretty near pinpoint the speed where your areo advantage overtook the weight advantage and it'd give you a clearcut answer to your question.
![](https://www.miataturbo.net/attachments/race-prep-75/161975-roof-no-roof-weight-v-aero-stock_zps5bb442be.jpg?dateline=1455138370)
#15
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
This is where virtual dyno is really cool. Make a 4th gear pull with the top and without the top, don't correct for the weight difference, and it'll give you an answer which is faster for any given speed.
I logged a couple pulls a long time ago in a NA8 with headlights up vs down and the areo difference showed up pretty big above 40mph.
I feel like you could pretty near pinpoint the speed where your areo advantage overtook the weight advantage and it'd give you a clearcut answer to your question.
![](https://www.miataturbo.net/attachments/race-prep-75/161975-roof-no-roof-weight-v-aero-stock_zps5bb442be.jpg?dateline=1455138370)
I logged a couple pulls a long time ago in a NA8 with headlights up vs down and the areo difference showed up pretty big above 40mph.
I feel like you could pretty near pinpoint the speed where your areo advantage overtook the weight advantage and it'd give you a clearcut answer to your question.
![](https://www.miataturbo.net/attachments/race-prep-75/161975-roof-no-roof-weight-v-aero-stock_zps5bb442be.jpg?dateline=1455138370)
#19
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How much does the "race roof" weigh? They are available here in the states at about 11lbs before you add the poly window.
Two guys who race in the same Classic Japanese class I do have done it already and say the weight saving is significant. they told me the figures at the time but i forget now...I just know its the next stage of car delveopment
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