XKR Super G... Going for Mach 1
08-26-2009, 12:09 PM
#861
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If you look up some drag racing info, you may find some helpful tips there. I know that the drag racers do as much as possible to change the front end and to reduce the width of the front tires, as that's where majority of the drag is created.
It was my understanding, however, that the high Cd from the front wheels was due to the width of the tires, not the fact that they were spinning as the article that Chebosto linked suggests. It does make sense, though.
I do know that XKR will have more than enough power to reach his desired speed and comfort level at those speeds so the Cd shouldn't matter as much as downforce to keep the car planted. Still, it wouldn't hurt to look into reducing the Cd a bit more inconspicuously.
Here's a website that could be of help:
http://www.recumbents.com/car_aerodynamics/
It was my understanding, however, that the high Cd from the front wheels was due to the width of the tires, not the fact that they were spinning as the article that Chebosto linked suggests. It does make sense, though.
I do know that XKR will have more than enough power to reach his desired speed and comfort level at those speeds so the Cd shouldn't matter as much as downforce to keep the car planted. Still, it wouldn't hurt to look into reducing the Cd a bit more inconspicuously.
Here's a website that could be of help:
http://www.recumbents.com/car_aerodynamics/
08-26-2009, 12:11 PM
#862
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the amount of power XKR is pushing really should negate the need for all this concern about wheel offsets. of course it'll be more stable and quieter but really the HP should do the trick. I am surprised the rear diffuser is even needed to be honest.
The bugatti isn't a very aero car and look what it did with 1k hp!
The bugatti isn't a very aero car and look what it did with 1k hp!
If you look up some drag racing info, you may find some helpful tips there. I know that the drag racers do as much as possible to change the front end and to reduce the width of the front tires, as that's where majority of the drag is created.
It was my understanding, however, that the high Cd from the front wheels was due to the width of the tires, not the fact that they were spinning as the article that Chebosto linked suggests. It does make sense, though.
I do know that XKR will have more than enough power to reach his desired speed and comfort level at those speeds so the Cd shouldn't matter as much as downforce to keep the car planted. Still, it wouldn't hurt to look into reducing the Cd a bit more inconspicuously.
Here's a website that could be of help:
http://www.recumbents.com/car_aerodynamics/
It was my understanding, however, that the high Cd from the front wheels was due to the width of the tires, not the fact that they were spinning as the article that Chebosto linked suggests. It does make sense, though.
I do know that XKR will have more than enough power to reach his desired speed and comfort level at those speeds so the Cd shouldn't matter as much as downforce to keep the car planted. Still, it wouldn't hurt to look into reducing the Cd a bit more inconspicuously.
Here's a website that could be of help:
http://www.recumbents.com/car_aerodynamics/
...I dont care....you guys say it...and i am going to keep asking him.....Its my azz thats going to be in this car..
.....With the entire suspension setup and wheels.....the car feels like I am driving at 100mph instead of 180+.....I will get videos the next outing
Thanks for the input guys.
Last edited by XKR; 08-26-2009 at 12:27 PM.
08-26-2009, 12:57 PM
#866
Based on the article provided by Cheston, the drag from the engine is indicated as being from “engine bits” hanging down. We will eliminate that altogether with the front portion of the underbody. Also, we will be eliminating the drag from the exhaust, some of the drag from the rear axle, and the drag under the car will be reduced.
there is no way to avoid this other than offering more venting for the engine bay. ie. cutting holes in the firewall toward the back of the engine and having air ducts on the side fenders for the air to escape..
Assume my car would have acheived 175 mph (it would have at least reached that for sure), and mike wants to hit 200 mph. 200^2 / 175^2 = 1.31. Let's say I had 550 whp at the time (I know it was less than that because I turned the boost down 3 psi and it was a hot day), Mike would need 720 whp to hit 200 mph assuming that the drag reduction we are getting with the underbody and the fact he won't be using a rear wing offsets the additional drag of his wheels sticking out a tad bit. I beleive that he will be running 800 whp at a minimum, so his HP should be adequate to get him there.
i know he will have more than enough power to reach his goals, its about getting there efficiently.
08-26-2009, 01:32 PM
#867
I assumed, perhaps mistakingly, that the drag from air entering the engine compartment through the radiator would be reflected in the 33.4% figure for the cooling package drag. If not, I would expect the 3.1% figure for the engines percentage of drag to be higher. The article is not clear on this point. In fact, other than the chart, the only time the article mentions the engine is when it references the bits hanging down.
Anyway, it is what it is. Mike can push out the rear fenders a bit, and that should help.
Last edited by ttg35fort; 08-26-2009 at 01:34 PM.
08-26-2009, 02:00 PM
#868
ugh. sorry. now i know what u meant. i had read somethign else after i posted the first link..
yea. that 3% is engine bits in the airstream.. but, still if u can aleviate air pressure inside the engine bay, that would be beneficial too...
air flowing over the top of the car comes in varying pressure zones, u can create airflow escape using the right venting..
yea. that 3% is engine bits in the airstream.. but, still if u can aleviate air pressure inside the engine bay, that would be beneficial too...
air flowing over the top of the car comes in varying pressure zones, u can create airflow escape using the right venting..
08-26-2009, 02:20 PM
#869
I haz da turbos
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I think with all this info i shall begin project "greasy weesel"
I too am going to be fabricating my own flat undertray. I'll be using a product called alucobond. Its incredibly light and incredibly strong.
Are you guys going to be enclosing the exhaust with the undertray? and if so, are you going to heat wrap it. I think i'm going to heat wrap mine up to the muffler just to prevent any excess heat from building up under the car.
I'm also going to be making some little plates that will attach to the front end of the wheel wells to cover up as much of the tire as possible.
I too am going to be fabricating my own flat undertray. I'll be using a product called alucobond. Its incredibly light and incredibly strong.
Are you guys going to be enclosing the exhaust with the undertray? and if so, are you going to heat wrap it. I think i'm going to heat wrap mine up to the muffler just to prevent any excess heat from building up under the car.
I'm also going to be making some little plates that will attach to the front end of the wheel wells to cover up as much of the tire as possible.
08-26-2009, 03:15 PM
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I agree....Thanks for the input...I think with all this info i shall begin project "greasy weesel"
I too am going to be fabricating my own flat undertray. I'll be using a product called alucobond. Its incredibly light and incredibly strong.
Are you guys going to be enclosing the exhaust with the undertray? and if so, are you going to heat wrap it. I think i'm going to heat wrap mine up to the muffler just to prevent any excess heat from building up under the car.
I'm also going to be making some little plates that will attach to the front end of the wheel wells to cover up as much of the tire as possible.
I too am going to be fabricating my own flat undertray. I'll be using a product called alucobond. Its incredibly light and incredibly strong.
Are you guys going to be enclosing the exhaust with the undertray? and if so, are you going to heat wrap it. I think i'm going to heat wrap mine up to the muffler just to prevent any excess heat from building up under the car.
I'm also going to be making some little plates that will attach to the front end of the wheel wells to cover up as much of the tire as possible.
As far as my plans are right now is to close up the rear only.....because the exhaust pipes in the center is already setup a groove ....so if the rear works as well as expected.....thats it for me..
Last edited by XKR; 08-26-2009 at 03:24 PM.
08-26-2009, 03:50 PM
#871
Terry
08-26-2009, 04:05 PM
#872
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Mike, have you put some thought into gearing yet? Or tire diameter?
If you are running a 3.3diff (which I think you are right now)....to hit 200 in 5th you'll be at 8500rpm (just over actually), or 6th is 6200rpm range on a stock dia tire.....only issue with that, is I know some trans have big issues with pulling an overdrive gear (6th) that hard that long. Maybe someone thats looked into the trans (briguy maybe or sirpierre) could shed some light on how good the squirters/pump is in our trans to cool/lubricate gears
Just thoughts
Tom
If you are running a 3.3diff (which I think you are right now)....to hit 200 in 5th you'll be at 8500rpm (just over actually), or 6th is 6200rpm range on a stock dia tire.....only issue with that, is I know some trans have big issues with pulling an overdrive gear (6th) that hard that long. Maybe someone thats looked into the trans (briguy maybe or sirpierre) could shed some light on how good the squirters/pump is in our trans to cool/lubricate gears
Just thoughts
Tom
08-26-2009, 05:00 PM
#873
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Mike, have you put some thought into gearing yet? Or tire diameter?
If you are running a 3.3diff (which I think you are right now)....to hit 200 in 5th you'll be at 8500rpm (just over actually), or 6th is 6200rpm range on a stock dia tire.....only issue with that, is I know some trans have big issues with pulling an overdrive gear (6th) that hard that long. Maybe someone thats looked into the trans (briguy maybe or sirpierre) could shed some light on how good the squirters/pump is in our trans to cool/lubricate gears
Just thoughts
Tom
If you are running a 3.3diff (which I think you are right now)....to hit 200 in 5th you'll be at 8500rpm (just over actually), or 6th is 6200rpm range on a stock dia tire.....only issue with that, is I know some trans have big issues with pulling an overdrive gear (6th) that hard that long. Maybe someone thats looked into the trans (briguy maybe or sirpierre) could shed some light on how good the squirters/pump is in our trans to cool/lubricate gears
Just thoughts
Tom
So far I am sticking with the 3.3.....that may change later after I test it with the new setup.... I am sticking with the 20's so I should have much better numbers from the stock
plus..Yokahama is sending me 3 sets plus a big azz sticker for my car
Dont forget now.....I will not be above 190 for long...2 reasons....1) My class will be in the 150 range
....not open class 190+...dont forget that...2) There are only a few areas that will allow you to hold those speeds. The reason I opt for this much power..is to get me from say for example ..130 to 190 in under 15 sec.....and the monster brakes to get me back to 90 or 70 for the corner and then back up as quick as possible.Say for example Tom you are running in my class and your cars real top speed is 170....all it would take for me to beat you is a few 180 or 190's to scrub tons of time off the clock. I think some people think that I will run at over 190 for 90 miles......not even my ####### could do that.
The trick is not to scrub off too much and get DQ'ed.I have received some PM's from people telling me that there is no way I can run a VQ 90 miles at 200mph...
...Not even a Ferrari or Lambo could do that..... But I told them I am not that crazyWinning my class at the SSC would be nice....but there is a sub group that puts big BIG $$$ on the line...
...so thats my REAL reason Tom...did you PM Sharif as yet???
Last edited by XKR; 08-27-2009 at 04:47 AM.
08-26-2009, 05:03 PM
#874
I think with all this info i shall begin project "greasy weesel"
I too am going to be fabricating my own flat undertray. I'll be using a product called alucobond. Its incredibly light and incredibly strong.
Are you guys going to be enclosing the exhaust with the undertray? and if so, are you going to heat wrap it. I think i'm going to heat wrap mine up to the muffler just to prevent any excess heat from building up under the car.
I'm also going to be making some little plates that will attach to the front end of the wheel wells to cover up as much of the tire as possible.
I too am going to be fabricating my own flat undertray. I'll be using a product called alucobond. Its incredibly light and incredibly strong.
Are you guys going to be enclosing the exhaust with the undertray? and if so, are you going to heat wrap it. I think i'm going to heat wrap mine up to the muffler just to prevent any excess heat from building up under the car.
I'm also going to be making some little plates that will attach to the front end of the wheel wells to cover up as much of the tire as possible.
In addition, we'll be using NACA ducts to provide air flow to the transmission and rear differential.
Last edited by ttg35fort; 08-27-2009 at 04:08 PM.
08-26-2009, 05:20 PM
#875
page 148 of Competition car aerodynamics , by Simon McBeath
but what can be done to alleviate the adverse effects of wheels? one of the most basic approaches would be to examine the size of wheel to use, since wheel drag is obviously proportional to wheel frontal area. usually this factor is tied down in the regulations, but if it isn't, and this part of the aerodynamics of the car is likely to be significant to performance, then it is probably worth considering, especially as the wheels can be such a big contributor to overall drag. After that is a case of trying to 'manage' the airflow around the wheels to lessen their adverse effects. Obviously, solutions depend fundamentally on whether the car is open-wheeled, or closed-wheeled, as well as technical regulation...
with closed-wheelers, the situation might appear to be simpler, but can in fact be more complex than with open-wheelers. Enveloping body work obviously shrouds the wheels from much of the air that they would otherwise encounter, and this is the basic reason we expect a lower drag coefficient from a closed wheeler, but air still enters the wheel wells from in front, underneath and out to the sides, and how it is dealt with can have significant effects.
Often, such efforts will involve ducts, cutaways, and louvres that help air escape from wheel wells. ... Cutaways often present on the vehicle sides behind the front wheels also assist air to escape no only from the wheel wells, but also from under the entire front of the car. As such these features often work in concert with front splitters and diffusers, providing an exit for air that has been exploited further forwards on the car...
with closed-wheelers, the situation might appear to be simpler, but can in fact be more complex than with open-wheelers. Enveloping body work obviously shrouds the wheels from much of the air that they would otherwise encounter, and this is the basic reason we expect a lower drag coefficient from a closed wheeler, but air still enters the wheel wells from in front, underneath and out to the sides, and how it is dealt with can have significant effects.
Often, such efforts will involve ducts, cutaways, and louvres that help air escape from wheel wells. ... Cutaways often present on the vehicle sides behind the front wheels also assist air to escape no only from the wheel wells, but also from under the entire front of the car. As such these features often work in concert with front splitters and diffusers, providing an exit for air that has been exploited further forwards on the car...
08-26-2009, 06:46 PM
#877
Registered User
sounds good mike....no no pm's yet lol
I've only gone up and down real quick to speeds (somewhere well north of 160as the speedo only reads to there.......but well it was well above that is all I know lol).....I didn't look at any of the gauges too much....was concerned with staying on the road lol.....and it is pretty sick how quick we can get up to above speedo speeds with some of these setups isn't it lol.
Um Sharif.....I'm waaaaaiiiiiitttttiiinnnggggg....
Tom
I've only gone up and down real quick to speeds (somewhere well north of 160as the speedo only reads to there.......but well it was well above that is all I know lol).....I didn't look at any of the gauges too much....was concerned with staying on the road lol.....and it is pretty sick how quick we can get up to above speedo speeds with some of these setups isn't it lol.
Um Sharif.....I'm waaaaaiiiiiitttttiiinnnggggg....
Tom
So far I am sticking with the 3.3.....that may change later after I test it with the new setup.... I am sticking with the 20's so I should have much better numbers from the stock plus..Yokahama is sending me 3 sets plus a big azz sticker for my car
Dont forget now.....I will not be above 190 for long...2 reasons....1) My class will be in the 150 range....not open class 190+...dont forget that...2) There are only a few areas that will allow you to hold those speeds. The reason I opt for this much power..is to get me from say for example ..130 to 190 in under 15 sec.....and the monster brakes to get me back to 90 or 70 for the corner and then back up as quick as possible.
Say for example Tom you are running in my class and your cars real top speed is 170....all it would take for me to beat you is a few 180 or 190's to scrub tons of time off the clock. I think some people think that I will run at over 190 for 90 miles......not even my ####### could do that. The trick is not to scrub off too much and get DQ'ed.
I have received some PM's from people telling me that there is no way I can run a VQ 90 miles at 200mph......Not even a Ferrari or Lamo could do that..... But I told them I am not that crazy
Winning my class at the SSC would be nice....but there is a sub group that puts big BIG $$$ on the line......so thats my REAL reason
Tom...did you PM Sharif as yet???
plus..Yokahama is sending me 3 sets plus a big azz sticker for my carDont forget now.....I will not be above 190 for long...2 reasons....1) My class will be in the 150 range
....not open class 190+...dont forget that...2) There are only a few areas that will allow you to hold those speeds. The reason I opt for this much power..is to get me from say for example ..130 to 190 in under 15 sec.....and the monster brakes to get me back to 90 or 70 for the corner and then back up as quick as possible.Say for example Tom you are running in my class and your cars real top speed is 170....all it would take for me to beat you is a few 180 or 190's to scrub tons of time off the clock. I think some people think that I will run at over 190 for 90 miles......not even my ####### could do that.
The trick is not to scrub off too much and get DQ'ed.I have received some PM's from people telling me that there is no way I can run a VQ 90 miles at 200mph...
...Not even a Ferrari or Lamo could do that..... But I told them I am not that crazyWinning my class at the SSC would be nice....but there is a sub group that puts big BIG $$$ on the line...
...so thats my REAL reason Tom...did you PM Sharif as yet???
08-26-2009, 07:14 PM
#878
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OK....I finally got a response from the guy who built my GT1 car.....I sent him a bunch of pictures including the ones below and asked if he saw a problem in his opinion with running this car at high speeds. I did not tell him what was in question...
He first asked if it was a stock body. He wanted to know if I did anything to the rear for it to extended further than the front...Once I told him it was stock...he then said that the more rubber you have to the ground the better... he said to get the wheel/tire as close to the top of the fender as possible without rubbing.
He did say that if you widen the rear to extent further than the front....you will have to do extra to counter the negative effects......I take it he is talking about changing the direction of the air.
THEN I told him why I am asking.....He said even if he though my offset was wrong....the only time that would make a difference is if you had a track only pro car that had a limited HP in its bracket, limited weight and so on...where any little wrong direction of air would affect your times......but running a street car with insane hp will not even matter.
I have a car in my garage that comes with 355 from the factory and the bottom of the wheels extend a little further then mine......If the car was not steady at 180 plus....this is something I would address....I am sure it will be OK.
He first asked if it was a stock body. He wanted to know if I did anything to the rear for it to extended further than the front...Once I told him it was stock...he then said that the more rubber you have to the ground the better... he said to get the wheel/tire as close to the top of the fender as possible without rubbing.
He did say that if you widen the rear to extent further than the front....you will have to do extra to counter the negative effects......I take it he is talking about changing the direction of the air.
THEN I told him why I am asking.....He said even if he though my offset was wrong....the only time that would make a difference is if you had a track only pro car that had a limited HP in its bracket, limited weight and so on...where any little wrong direction of air would affect your times......but running a street car with insane hp will not even matter.
I have a car in my garage that comes with 355 from the factory and the bottom of the wheels extend a little further then mine......If the car was not steady at 180 plus....this is something I would address....I am sure it will be OK.
Last edited by XKR; 08-26-2009 at 07:25 PM.
08-26-2009, 08:43 PM
#879
Hey so are you going to have a navigator with you? What are your plans for timing? Because you do have a "target speed" right? and are trying to finish at .000 I assume? I ran the BBORR this past April and by pure luck had an average speed of 124.952 in the 125 target speed class and ended up with a 3rd place trophy@ 1.3 seconds fast...which means there were two other competitors UNDER 1.3 seconds over 118 miles..CRAZEE! Believe it or not, I used a 10 dollar digital kitchen timer from walmart! LOL I set it up to count DOWN 28:32 for the first leg of 59 miles and deducted the 32 seconds fast that I was at the half way point..raced second leg and stopped the timer as I crossed the line. Couldn't freaking believe it read 0000 when I looked after I parked!.just curious what you're thinking. I assume you are planning on running the NORC next spring right? I have thought about doing the BBORR AND the norc next year..just not sure I can go to Nevada right after the BBORR. We'll see!
08-26-2009, 08:47 PM
#880
I searched, but unfortunately I could not find Amuse fenders for a G35. The TS vent is pretty small and pretty high up on the fenders. The Seibon fender's vent is a little larger, but still a little high up.
Someone needs to make those Amuse fenders for the G35, PPPLLLLEEEAAASSSEEEE.
Oh, and while their at it, make them 2" - 2.5" wider than stock, and make a rear fender kit that increases the width by the same amount. And please don't make us buy bumpers we won't use.
Someone needs to make those Amuse fenders for the G35, PPPLLLLEEEAAASSSEEEE.
Oh, and while their at it, make them 2" - 2.5" wider than stock, and make a rear fender kit that increases the width by the same amount. And please don't make us buy bumpers we won't use.
Last edited by ttg35fort; 08-26-2009 at 08:48 PM.