Weight Vs Aerodynamics
Discussion
Remember, aerodynamic drag increases at the square of speed, so aerodynamics can play a much bigger part in your performance than weight can. We gained a lot more et and mph by swapping to a pro stock hoodscoop and rear wing than we did by shedding 80lbs.
Edited by anonymous-user on Friday 9th November 19:08
I remember Fast Freddy telling about his move to TMFC (something like that) :
"The pickup was not going faster, even if we would add 500 hp,
at 350 Km/h it is just like running into a wall,
and the rear wheels keep on smoking"
So my guess is, too, that weight counts for the first half of the track,
aerodynamics count on the second half.
"The pickup was not going faster, even if we would add 500 hp,
at 350 Km/h it is just like running into a wall,
and the rear wheels keep on smoking"
So my guess is, too, that weight counts for the first half of the track,
aerodynamics count on the second half.
Benni said:
I remember Fast Freddy telling about his move to TMFC (something like that) :
"The pickup was not going faster, even if we would add 500 hp,
at 350 Km/h it is just like running into a wall,
and the rear wheels keep on smoking"
So my guess is, too, that weight counts for the first half of the track,
aerodynamics count on the second half.
I remember hearing that too. While I can understand how as a racer he wanted to go faster and stay competitive in Pro Mod I would far rather have his pickup than his funny car on the track. We'll just have to hope he can be pursuaded to do demo runs with the pickup. "The pickup was not going faster, even if we would add 500 hp,
at 350 Km/h it is just like running into a wall,
and the rear wheels keep on smoking"
So my guess is, too, that weight counts for the first half of the track,
aerodynamics count on the second half.
Or maybe do a little bit of tinkering and enter it in Street Eliminator - after all it started on the street :-)
Here is one i always argue with my mate about aerodynamics, He says it doesnt matter too much, I say it does. A couple of year ago i had my windscreen fall in on my knee while i was racing and hit my skid lid and landed on my lap, So i left it on the floor for the rest of the day and the next too. Thinking i would get maybe upto .4sec quicker i tryed my best and couldnt get any quicker with no windscreen with the roof off. This was half hour later so all the conditions were the same 
If you dont know how flat my windscreen is or how unaerodynamic my race vehicle is you can see it on my profile. 
If you dont know how flat my windscreen is or how unaerodynamic my race vehicle is you can see it on my profile. v8 jago said:
Here is one i always argue with my mate about aerodynamics, He says it doesnt matter too much, I say it does. A couple of year ago i had my windscreen fall in on my knee while i was racing and hit my skid lid and landed on my lap, So i left it on the floor for the rest of the day and the next too. Thinking i would get maybe upto .4sec quicker i tryed my best and couldnt get any quicker with no windscreen with the roof off. This was half hour later so all the conditions were the same If you dont know how flat my windscreen is or how unaerodynamic my race vehicle is you can see it on my profile.
Cool picture! If you dont know how flat my windscreen is or how unaerodynamic my race vehicle is you can see it on my profile. What's behind you? I mean, can the air blast straight through the cabin and out the back, or does it hit something behind you?
Thanks for all replies, we got car weighed at National Finals and it was alot heavier than we would of like so car is on a diet for next year, as for aerodynamic side of things, this is where I think the car needs improving, yes its an altered and its never going to be the best for this but every little bit helps.
Lee, what difference on ET and mph did weight loss compared to aerodynamics was there?
Lee, what difference on ET and mph did weight loss compared to aerodynamics was there?
BennettRacing said:
Lee, what difference on ET and mph did weight loss compared to aerodynamics was there?
The weight loss alone gave us around 3/100ths and made very little difference to the terminal speed...the advantage was all pretty much between 60ft and 330ft. Switching from our 10" tall brick of a cowl induction to a pro stock scoop and ditching the stock Z/28 "ducktail" added 3mph to our terminal speed instantly. Our best speed with the cowl induction and Z/28 spoiler was 176mph, with the pro stock scoop and wing, rear undertray and inner fender panels we've ran 184mph. And the difference in the tuneup is very marginal, in fact the terminal speeds at the 1/8th are within 1mph. ET-wise we went from a best of 7.71 to a 7.65 with virtually the same tune-up again. If it's easy to remove then ditching weight is a very simple way to add performance, but I think aerodynamics is often very under-estimated. We've hit a similar wall to what Freddy was describing aero-wise. There are stock bodied Camaros faster than ours but not many, and they all do it with a lot more horsepower. Camaros are notoriously poor in the wind tunnel, especially with the stock rain gutters like ours and no amount of extra power seems to push her through the air any faster that 183-184mph now. We've researched aerodynamics quite a lot in our quest for performance over the past few seasons and and as an example, it takes an extra 60-75 horsepower to push our car through the air above 150mph than an Olds Cutlass Supreme. At 180mph that difference must be even greater, possibly double. Makes you think eh?
I think personally that you'd gain a marked imrpovement in back half numbers by improving the CD of your altered, look at the terminal speeds that Chaos has ran. It's true that a weight loss will get the car out of the hole quicker but without being able to cut through the air at the sharp end I still think there'll be room for improvement.
Rat_Fink_67 said:
I think personally that you'd gain a marked improvement in back half numbers by improving the CD of your altered, look at the terminal speeds that Chaos has ran. It's true that a weight loss will get the car out of the hole quicker but without being able to cut through the air at the sharp end I still think there'll be room for improvement.
But whatever you do, don't sacrifice aesthetics - remember that hideous photoshop job of Freddy's truck with a snowplough front end? And your car can't be any worse than ours for aerodynamics - the firewall is recessed, the screen flat and I doubt the doorhandles and mirrors help...Rat_Fink_67 said:
BennettRacing said:
Lee, what difference on ET and mph did weight loss compared to aerodynamics was there?
The weight loss alone gave us around 3/100ths and made very little difference to the terminal speed...the advantage was all pretty much between 60ft and 330ft. Switching from our 10" tall brick of a cowl induction to a pro stock scoop and ditching the stock Z/28 "ducktail" added 3mph to our terminal speed instantly. Our best speed with the cowl induction and Z/28 spoiler was 176mph, with the pro stock scoop and wing, rear undertray and inner fender panels we've ran 184mph. And the difference in the tuneup is very marginal, in fact the terminal speeds at the 1/8th are within 1mph. ET-wise we went from a best of 7.71 to a 7.65 with virtually the same tune-up again. If it's easy to remove then ditching weight is a very simple way to add performance, but I think aerodynamics is often very under-estimated. We've hit a similar wall to what Freddy was describing aero-wise. There are stock bodied Camaros faster than ours but not many, and they all do it with a lot more horsepower. Camaros are notoriously poor in the wind tunnel, especially with the stock rain gutters like ours and no amount of extra power seems to push her through the air any faster that 183-184mph now. We've researched aerodynamics quite a lot in our quest for performance over the past few seasons and and as an example, it takes an extra 60-75 horsepower to push our car through the air above 150mph than an Olds Cutlass Supreme. At 180mph that difference must be even greater, possibly double. Makes you think eh?
I think personally that you'd gain a marked imrpovement in back half numbers by improving the CD of your altered, look at the terminal speeds that Chaos has ran. It's true that a weight loss will get the car out of the hole quicker but without being able to cut through the air at the sharp end I still think there'll be room for improvement.
At the National finals we had a new fuel tank on board that lost us 45lbs weight (we put 29lbs back in weight bar to start with) yet the 330ft was still quicker than the 6's we ran.
Think the weight were getting out the car is going to give us better 60/330ft times, and some bits were doing are sure to help the car top end, although we are the only methanol car in the NFAA to run 200+ with a standard roots blower so car must have ok aerodynamics....but it all helps.
Weight was my biggest worry though when we got it weighed was HEAVY, so lots to come off.
One thing I would love to do is get the car in a wind tunnel just to see what works and what doesn't...
We're quite lucky in some repects because a lot of wind tunnel data exists for our car, whereas with your altered I'm not sure if anyone's ever tested one. As mentioned previously, don't sacrifice aesthetics too much though; as strange as it sounds, on a Camaro one of the easiest ways to lower drag is to place a completely flat panel in front of the grille, right down to the floor. There's no way in hell we'd ever do that though because it'd look awful. With the sparse bodywork of an altered though I'm sure there is quite lot than can be done to improve matters, I imagine the drag of the rear tyres and engine must be immense.
Luke;
one thing you could consider is a different rear wing, from what I remember of the current one (correct me if I'm wrong) but its got quite a thick leading edge which is one of the biggest factors in drag of an aerofoil section, also the profile of the aerofil, the larger the curve in the profile the more downforce it will create at a lower angle of attack, however this creates a lot more drag - its a balancing act
another thing, maybe different wing struts? If you've got tubular struts consider tear drop section struts like fuellers etc use as a cylinder/tube is one of the least aerodynamic shapes
not sure how much difference a full belly pan would make on an altered but combined with something wrapping around the front of the chassis is something I've pondered quite a bit in terms of tidying up air flow without ruining the look of the car
one thing you could consider is a different rear wing, from what I remember of the current one (correct me if I'm wrong) but its got quite a thick leading edge which is one of the biggest factors in drag of an aerofoil section, also the profile of the aerofil, the larger the curve in the profile the more downforce it will create at a lower angle of attack, however this creates a lot more drag - its a balancing act
another thing, maybe different wing struts? If you've got tubular struts consider tear drop section struts like fuellers etc use as a cylinder/tube is one of the least aerodynamic shapes
not sure how much difference a full belly pan would make on an altered but combined with something wrapping around the front of the chassis is something I've pondered quite a bit in terms of tidying up air flow without ruining the look of the car
Edited by MotorPsycho on Monday 12th November 13:55
Thats the thing I think I need to remember, its an altered and at the end of the day its not gonna be the best for aerodynamics, would not change rear wing car is very stable top end and never moves about even when it ran 200.
Next year I am looking to run mid 6's at 215ish so need to take things like aerodynamics bit more seriously, everything I can do to help the car is gonna improve our ET's and MPH.
Next year I am looking to run mid 6's at 215ish so need to take things like aerodynamics bit more seriously, everything I can do to help the car is gonna improve our ET's and MPH.
Luke - Out of interest - How heavy is your car? Chaos tips the scales at 2225 with driver after a run. We are looking at trimming a little off that wihout upsetting the front to rear weight ratio too much. Aero wise we're not going to get any better. On that 218mph run it was so stable I drove the last 200ft with my hand up in the roof on the chute levers.I'm looking at ways of improving the first half performance thru things such as gearing etc as that little motor needs all the help it can get to the car moving - Remember it's only 420ci.The rear wing section is definitely worth looking at.
WrightRacing said:
Luke - Out of interest - How heavy is your car? Chaos tips the scales at 2225 with driver after a run. We are looking at trimming a little off that wihout upsetting the front to rear weight ratio too much. Aero wise we're not going to get any better. On that 218mph run it was so stable I drove the last 200ft with my hand up in the roof on the chute levers.I'm looking at ways of improving the first half performance thru things such as gearing etc as that little motor needs all the help it can get to the car moving - Remember it's only 420ci.The rear wing section is definitely worth looking at.
We got it weighed at National Finals was 2109lbs with my old man. Corner weights were spot on so was happy with that.Stability is not our problem either like you say soon as my old man is in 3rd he drives one handed and other hand is on chute lever.
Think next year when funds permit we will get new aero tube wing struts and a few others bits a pieces to help it through the air.
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