Highest recorded top speed of 3/S? Has anyone ever broke 200mph...

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Originally Posted by mehrshadvr4

your car must have tons of drag to get only that much with 3 times the stock whp. the stock first gen vr4 does over 160 with the spoiler down.i'm building my car for highway roll racing mostly so I've some ideas to how make the car as aerodynamic as possible. the first is to use stock shape hood and front bumper with blocked unnecessary hols(i can make a bracket for the licence plate to block one of the side holes, no rear spoiler and front spliter and rear diffuser (no fuel tank for the best possible diffuser angle and shape, will have fuel cell in the trunk for that). covering even under the engine and not just the front half of the car. using small NASA ducts on the hood for removing heat and feeding cool air. race mirrors for look and better aero. there is hidden curve on our cars because of the big ass mirrors on the door. i noticed it on Nelson's car and got the idea from him. the car looks much better with out the mirrors on the doors and the curve from finder to the door makes the car looks more wide body than before.
http://i108.photobucket.com/albums/n...nelsonscar.jpg
http://i165.photobucket.com/albums/u...son/948073.jpg

if i can make it happen i'll cover the exhaust and ds under the car to have under the car as flat as possible. the rear engine cars are so easy to make the under flat. my friend's mr2 is also all flat till the rear where the engine is. i also noticed prius have something like a small mud flap in front of the tire to cut air around them. i saw the same thing on a new mazda 3 today too so this must have some effect on aerodynamic.

http://i108.photobucket.com/albums/n...had/mazda3.jpg

GTR has a really similar hood as our 2ng gen hood and we might be able to use the vents from gtr on our hood. got to do some measuring, unless someone here do it before i do it. little to no drag and still having ventilation. :D
http://d3gc35l9g9ughp.cloudfront.net...od-600x397.jpg

all that plus making the car lighter. :D

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The flaps in front of the wheels is to provide more grip. So that the wheel dont have to roll over a cushion of air. I think the air resistance would be the same as far as aerodynamics.

Also those are intakes not vents on the gtr. If you where to put an intake on the hood i would place just one of those in the left lower corner to provide fresh air straight to the intake. Then a vent or two on the top position of the hood(hot air raises). Like the two vents on the 575 hood.

that's my plan, but on gtr they don't go to the intake as far as i can see. it looks like people use revered nasa duct to exhaust hot air. i am thinking to put one facing forward and two facing back.
revered vents
http://stwot.motortrend.com/files/20...e-1024x640.jpg
http://www.japanesesportcars.com/gal...gtr-engine.jpg

J. Fast, as promised:

• 26" from the floor to the top of my front wheel well arc.
• 17" from the floor to the top of the intercooler opening.
• Under the front of my bumper is a reinforced airdam that a 3" floor jack will not slide under without forcing it. This goes side to side in an arc as the stock '99 does.

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Originally Posted by vr4tune

This and more importantly the fact you don't have any under plastics on the car. I also noticed your fmic is hanging down below the bumper.

Side windows are a HUGE FACTOR. Example: I've heard that a torga top Supra with the top off can't go much over a 100 with out the rear window poping out. Maybe hellbringer can verify this as he has a lot of supra knowledge.

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That's complete BS -- I've been quite a bit faster with the top off numerous times. It definitely does make a significant difference, though. The tracks are laid back enough here that I could probably get away with making a pass or 2 with the top off the green car just to see the difference.

On the topic, I think you'd need at least a legit 550WHP to hit a verified 200MPH on a pristine road. You'll need a setup that can effectively breath in the higher RPM's, which crosses most TD04 setups off the list. Eventually hitting 200MPH on a long enough road is one thing, but I'd more interested in seeing someone actually do it (or at least try it) at one of the Mile events. From what I've observed, it takes a legit 700WHP minimum for a Supra to hit 200MPH in the standing mile and ~900WHP to go 215MPH.

Hi JFast - Haven’t seen you for a while – glad you’re still on top of things.

To answer you question – I think 525 HP will take you to 200MPH, but as others have said, you’ll have to do something regarding your areo. Large open mouth grill areas do look quite cool but they are horrible when it comes to drag. I have no idea as to which year our cars had the least drag, but just by looking, it seems that my 1991 is a lot slipperier than your exposed intercoolers. Just my thought.

As you are very well aware, long pulls are significantly different than a flash dyno reading. Heat begins to build all over and perhaps your engine management system is pulling spark due to or in anticipation of detonation or other thermal engine damage.

As others have voiced, aero drag increase at about the square of speed but other parasitic drag occurs as well. Tire rolling resistance in addition to other rotational drags all add up. Also at higher speed, turbulence might begin to show it’s face and turbulence really kills speed. When it comes to airflow, turbulence is a total killer - it is way better to allow the air to flow around a car rather than through it

The underbody on my car is quite smooth as compared to some others. There are several air shields to flow the air where the Mitsu engineers wanted it to go. My car even has an air deflector in front of the radiator to help the air movement around the area in front of the a/c condenser. My recommendation is to keep all the underbody plastic stuff in place ‘cause it probably helps.

Contrary to another’s post, Bonneville salt has more drag than does dry concrete and the drag becomes more severe as the salt surface gets wetter. The SCTA allows record runs only in the early morning when the air is cooler and quieter too. A supercharged vehicle might very well run faster during the heat of the afternoon because of the higher density altitude but it’s prudent to ask someone who knows for sure. Like you indicate, thin air has less drag.

Here is a top speed site that I contribute to.

Landracing Forum Home - Index


The posters on this place are all experienced top speed racers and will be able to tell you what it takes to get to your 200 mph goal. Our aero might be comparable to a Camaro or Firebird and the numbers require to do whatever with those cars will be very well known by the participants on this site. Most have exceeded 200 dozens of times so the knowledge base is quite complete. You have to register and post in the correct areas but the response you will get is going to be amazing. Be advised it might not be too smart in reveling your high-speed stuff on the public highways because these guys are seasoned top speed racers – there is a place for speed and I-70 east of Denver is not it – LOL.


To demonstrate how important aero is, here is a video of the BudFab motorcycle streamliner. He uses a 50 CC (three cubic inch motor) and went 147 mph.

http://www.youtube.com/watch?v=mYINrhTNiyM



In closing, here are a couple of videos of some a-hole idiot running his Stealth at Bonneville. He just doesn’t have enough motor! I ought to know ‘cause I rebuilt the entire car and it’s me doing the steering! LOL.

http://www.youtube.com/watch?v=Bbwg8anqM30

http://www.youtube.com/watch?v=M0ozMzvrhfA

I would like to say my SL has been topped at 150mph, (corrected 142mph) at the time it was only a little over 200hp..

I can't imagine it would take more then 500+whp to brake the 200mph barrier in our cars.

I am in disbelief about DR's speed claims simply because there is no proof no videos or anything....any one doing such a high speed claim in a 3/s would think to record it....

I would really like to see someone document a 200mph speed test....

There is no way in hell you could get me to make a video of myself breaking the law and put it on the internet for all to see.

lol. but its done of course in mexico....

Me and hundreds of thousands of other people do it on a daily basis. have for years.

I have lots of friends who do too, I have yet to ever personally come across anyone who has ever got in trouble over it. maybe if your completely stupid and put your full information or something on it :P

its not worth it for police to spend the time and money watching internet videos to find such videos and then hunt you down and punish you for a crime that is AT MOST punishable with a fine, suspended license, and a few days in jail that would probably be served in hours allowing you to return home daily.

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Originally Posted by Blackmount

Me and hundreds of thousands of other people do it on a daily basis. have for years.

I have lots of friends who do too, I have yet to ever personally come across anyone who has ever got in trouble over it. maybe if your completely stupid and put your full information or something on it :P

its not worth it for police to spend the time and money watching internet videos to find such videos and then hunt you down and punish you for a crime that is AT MOST punishable with a fine, suspended license, and a few days in jail that would probably be served in hours allowing you to return home daily.

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Please take a second to mature. Just because you and your "hard ass" friends think its cool to post videos of yourselves endangering civillions on a "daily basis" does not mean everyone should. A respectable business like DR doesn't need to post up a video of themselves breaking the law. "A fine, suspended license, and a few days in jail" is pretty serious shit. I don't know Matt personally, but I doubt he would risk the aforementioned consequences to back up his top speed claims to the guy with the n/a who calls B.S.

Still call BS.

its not being a hard ass, its videography, and documentation.

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Originally Posted by Blackmount

I would like to say my SL has been topped at 150mph, (corrected 142mph) at the time it was only a little over 200hp..

I can't imagine it would take more then 500+whp to brake the 200mph barrier in our cars.

I am in disbelief about DR's speed claims simply because there is no proof no videos or anything....any one doing such a high speed claim in a 3/s would think to record it....

I would really like to see someone document a 200mph speed test....

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And I was just thinking about removing you from my ignore list...

If you guys want to continue having a community that's made up of bullshit and no one ever proves anything sure go for it

oh by the way I just ran a 7.8 in the 1/4 mile.

you guys r ridiculous sometimes.

Lets get serious, 216 mph in a 3/s doubtful. Our cars arn't built for that kind of speed, I feel it would need major modifcations to the body to ever do so and not blow to pieces or act like its going to fall apart and be completely unstable.

Like I said, I'll believe it when I see it... he doesn't have to show hes doing it on a public road, he can just show speedometer. Like my video, he could be on a private runway for all we know. if he doesn't want to show a video, their r plenty of otherways of recording speed.

I apologize I don't nut hug his every post, and think everything he says is pure gold.

Damn, I had a long winded post and it got ate.... laaaaaame!

Long story short, the frontal area calculations on the wiki are incorrect.

I calculated them today with real measurements on real cars and determined the following dx/dy 's

1G Stealth 22.417sf
My car 23.597sf
3G 3000gt 22.924sf

These are actual calculations and should be updated into wiki.

I have discrepancies in my previous posted data. I neglected to account for a number of additional drag coefficients. These should be added to the stock 0.39 Cd.

My wing 0.01
Missing under tray 0.01
Novara Bumper SMIC cutouts 0.01
OWindows removed 0.02
Wider tires 0.003

My actual Cd at time of testing was likely around 0.443. Not accounting for those was an oversight on my part.

Polygon, with your drop change your Cd to 0.375. For every 1" of drop our CD is reduced by -0.01

When you re enter all the data with the corrections it works out.

I appreciate the feedback on my setup everyone! I'll be bolting on the good s*** real soon and will have significantly different results!

you could still pass 180 with 720whp. first gen viper has shitty aerodynamic and it's something like .45dc and it could do 180 with only 450bhp. supra has good dc like .32 with wing. damn our car is like a parachute compare to other japanese sport cars.

Automobile drag coefficient - Wikipedia, the free encyclopedia

Here is a table regarding the aero for many cars. Examination of these makes me think our platform might be significantly better than Cd-0.44 but then again, looks can be mis-leading. Also check the CdA at the bottom of the article.

mehrshadvr4 is dead on regarding the early Vipers - they look good but in reality are quite dirty in the drag area.

I’m in agreement with the guys calling bullshit - show me your time slips or at least a GPS video. A speedo video alone is not enough for me - there is a video on youtube showing a speedo at some ridiculously high speed but by listening to the sound of the engine/car it seems to be on jack stands. Also agree with others regarding what it takes to get to 200 mph – some weird things begin to happen at speeds well below that threshold. It’s not easy folks – merely ask anyone who’s been successful in so doing.

Jfast - I like your dedication and enthusiasm as well as your organized approach for data acquisition and problem solving.

Just a thought but we might want to spend some time on Google looking at Cd definitions and The Bonneville Salt Flats too.

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Originally Posted by FeaRpb

If everything is ready, I plan on hitting the Texas Mile in March.

Going to past events there and seeing which cars are in the 190-200 bracket makes me feel that I can achieve my goal of 200mph in the mile.

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Hope u signed up because the event sign up list is filled up!

Yeah, I read that yesterday. It will more than likely the June event. If not, then Oct.

Post via Tapatalk

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Examination of these makes me think our platform might be significantly better than Cd-0.44 but then again, looks can be mis-leading.

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Aero in the macro is very easy and straightforward but in the micro it can be verrrry weird.

There's a reason why F1 teams spend so much money on CFD and then go back up the simulations in a physical tunnel.

Top speed is rarely a power vs drag issue. Sure, you must have enough power to overcome drag, but aero lift, handling balance, and suspension reaction play increasingly important roles, especially on real roads. There's a reason why the land speed guys play on salt flats.

DG

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Originally Posted by DG

Top speed is rarely a power vs drag issue. Sure, you must have enough power to overcome drag, but aero lift, handling balance, and suspension reaction play increasingly important roles, especially on real roads...

DG

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Indeed. What I've concluded is the answer to their significance is substantiated by effective modeling. My approach to this process involves individual component disassmebly, and combined modeling. Take it apart and measure each puzzle piece, put all the puzzle pieces back together, and test your puzzle.

I cannot express in words the countless hours I've spent (because of the inquisitiveness of my mind) taking the these damn cars apart. Every nut, bolt, panel, piece, everything... Some might think its ridiculious to disassemble every mechanical component on our cars by hand and measure, mark, model, research, and collaborate with professionals whom have a very specific expertise on chassi, aero, handling, engines, and suspension setup, but I don't. What I've learned above all, experts can only give you answers with real data. You must be able to answer their qualifying questions in order to get legitimate feedback. Part of the research and collaboration process involves taking it all apart, scrutinizing, evaluating function, engineering intent, as well as cause and effect. The more data you collect, the tighter your resolution gets.

It was actually you who pointed out to me on 3stech many years ago where and how to find my answers in the beginning... They were in a book. That book became a center focus point for all things built to go fast... And WIN.

For that I'd like to tip my hat to you sir. You pointed me in a direction. From there I found my own way.

I sometimes laugh quietly to myself about the most ridiculous things that I've likely collaborated and collected data on (which gave me results) that I choose not to share... and wonder why so many have it all wrong. They identify a problem and come up with solutions and opinions with no data or modeled puzzle pieces.

Btw, I about spit pop out of my nose when I read in 2001 someone went to 216 miles per hour. I don't think anyone had more than 500 horsepower back then. 216mph... b******* lol!

Glad I'm not the only one. :) Anxious to see what might come out of this thread. I have already learned quite a bit of information that may prove handy in the near future.

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Originally Posted by J. Fast

Indeed. What I've concluded is the answer to their significance is substantiated by effective modeling. My approach to this process involves individual component disassmebly, and combined modeling. Take it apart and measure each puzzle piece, put all the puzzle pieces back together, and test your puzzle.

I cannot express in words the countless hours I've spent (because of the inquisitiveness of my mind) taking the these damn cars apart. Every nut, bolt, panel, piece, everything... Some might think its ridiculious to disassemble every mechanical component on our cars by hand and measure, mark, model, research, and collaborate with professionals whom have a very specific expertise on chassi, aero, handling, engines, and suspension setup, but I don't. What I've learned above all, experts can only give you answers with real data. You must be able to answer their qualifying questions in order to get legitimate feedback. Part of the research and collaboration process involves taking it all apart, scrutinizing, evaluating function, engineering intent, as well as cause and effect. The more data you collect, the tighter your resolution gets.

It was actually you who pointed out to me on 3stech many years ago where and how to find my answers in the beginning... They were in a book. That book became a center focus point for all things built to go fast... And WIN.

For that I'd like to tip my hat to you sir. You pointed me in a direction. From there I found my own way.

I sometimes laugh quietly to myself about the most ridiculous things that I've likely collaborated and collected data on (which gave me results) that I choose not to share... and wonder why so many have it all wrong. They identify a problem and come up with solutions and opinions with no data or modeled puzzle pieces.

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^ that's all great but you failed to use commonsense in your initial calculations that a big ass wing hanging off the back, your open windows and gaping front end, may negatively affect drag/top speed:)

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Originally Posted by J. Fast

To the guys saying they broke 180mph, hell even 200mph. Today, I pointed my car east and dropped the hammer 3 times for 8 flat and straight miles. 186mph... that was all she had and my SAEwhp is 720whp. So... I'm asking what's going on with the 180+mph guys and inquiring about those who claimed breaking 200mph.

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Also, commonsense, to most people, not to use HIGHLY corrected whp for comparisons. ;)

Out of curiosity, are you intending to do some sort of top speed competition or is it just analysis fun?

Matt M also made those runs at higher elevation than most and in NM there are literally roads that dont turn for miles and miles. I have no reason not to believe Matt considering how easily my car stuck the speedo past 180 down here at sea level. Literally on a highway paralleling the ocean.

No intentions of ever doing something like that again either.

Jason

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Originally Posted by familyMAN

^ that's all great but you failed to use common sense in your initial calculations that a big ass wing hanging off the back, your open windows and gaping front end, may negatively affect drag/top speed:)



Also, commonsense, to most people, not to use HIGHLY corrected whp for comparisons. ;)

Out of curiosity, are you intending to do some sort of top speed competition or is it just analysis fun?

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Well, I knew the physics couldn't be defeated. It was easy to see the errors when I didn't get the results I anticipated. That's what data acquisition is for.

This was more less a test of current capability before I start bolting aero components on. I actually anticipate approaching 185 miles per hour on the straight away at the racetrack Erron linked to. Obviously its less than ideal t do it with my vehicle setup like this :p .

I was curious as to whether or not anyone has ever really discussed what it takes to crack 200mph. I'm not that far off. I'm willing to give it a go in North Carolina or the desert.

I'm sorry but everyone models SAE for the sake of comparison. Bring your happy little 700 wheel horsepower cars here and get 550 :p .

I don't really care about discussing possibilities. I care about the data that came from my testing. It's invaluable to me and I'm happy to share.

Many will benefit from this data later.

There was a lot of really good stuff dropped in here by Jake. Anyone have thoughts on that? specifically the 2008 and 2011 GTR? I believe I have a side by side photo comparison. (Man, it's freaky how close to comparison my car is to my buddy Steve's gtr)

I did see some mixed results online regarding the drag coefficients for cars. Does anyone disagree with the information I'm using from the actual wind tunnel? Ayone have additional data or opinions regarding the drag coefficients for different model years and styles of 3/S?

Why not? :)

For comparisons sake, on Top Gear Clarkson hit 200 mph (speedo indicated) in a stock Porsche 997 turbo, with 473 bhp, which is about 415-420 wheel horsepower on those cars. The factory claim is 193, and has been verified with track telemetry. It weighs about 100 to 200 lbs less than a 3S. With an exhaust and flash tune only, several guys have hit 200+ with about 540 bhp, so about 480ish whp.

I know you mentioned your wider tires (that probably stick out past fenders) but have you thought about your wheel design? If I recall correctly, you have concave grids...bet you are taking a drag hit with those as well vs a stock vr4 wheel.

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Originally Posted by mehrshadvr4

that's my plan, but on gtr they don't go to the intake as far as i can see. it looks like people use revered nasa duct to exhaust hot air. i am thinking to put one facing forward and two facing back.
revered vents
http://stwot.motortrend.com/files/20...e-1024x640.jpg
http://www.japanesesportcars.com/gal...gtr-engine.jpg

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Yeah that's a fail. Reverse NACA ducts are for show. NACA ducts are designed (back before many of us were born, mind you) to be a source of air induction with minimal drag. They do not work in reverse when you flip them around (to vent). No such thing. If you wanted to vent air out of the hood, you would want to get a JGTC hood, or get some low profile louvered vents and rivet them to your hood. (or weld them if you want it relatively seamless)


Welcome to the wonderful world of aerodynamics. I was hoping that I could wow some people when I get my car back in town and in my garage to fab up a front splitter, underbody tray, and a diffuser (basically make the car as slick as possible) but it looks like you guys are onto it already...My guestimations lead me to believe that 200mph can be had with 550HP and a very well designed aerodynamic package. It would just take a bit of sense and patience to get everything ironed out.

You want the front of the car as low as you can, and the rear can be less so if you have a flat underbody. That in itself would cause a pressure differential and you would get downforce out of it without creating any additional drag like you would from adding a wing. A front splitter will increase this effect if it is actually built correctly (IE: Angled down and matching the rake of the rest of the car, not that skillard splitter that just sticks straight out and looks goofy)

PS: Remove mirrors plz. The lincoln mark 8 ran 181 mph with under 300 horsepower back in '93 with MINOR aerodynamic mods.


oh yeah, and spend lots of time on Time Attack Forums. Lots of good information.
Also, check out mulsannecorner.com. Literal goldmine of race engineering.


EDIT: Oh yeah, at higher altitude you make less power because the air is thinner...but you also suffer less from drag because the air is thinner.

A full weight Stealth that would run 10.90's and trap 130 at 3000 ft. elevation, (without the NOS) and you guys are telling me it didn't have the power to hit two bills...? And calling BS on Matt?

What the hell reason would Matt have to bullshit anyone...?

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^

If you guys think one of the mainstays of the entire community of the last 15 years is a liar....

^^ Exactly what I was suggesting earlier.

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Originally Posted by J. Fast

Well, I knew the physics couldn't be defeated. It was easy to see the errors when I didn't get the results I anticipated. That's what data acquisition is for.

This was more less a test of current capability before I start bolting aero components on. I actually anticipate approaching 185 miles per hour on the straight away at the racetrack Erron linked to. Obviously its less than ideal t do it with my vehicle setup like this :p .

I was curious as to whether or not anyone has ever really discussed what it takes to crack 200mph. I'm not that far off. I'm willing to give it a go in North Carolina or the desert.

I'm sorry but everyone models SAE for the sake of comparison. Bring your happy little 700 wheel horsepower cars here and get 550 :p .

I don't really care about discussing possibilities. I care about the data that came from my testing. It's invaluable to me and I'm happy to share.

Many will benefit from this data later.

There was a lot of really good stuff dropped in here by Jake. Anyone have thoughts on that? specifically the 2008 and 2011 GTR? I believe I have a side by side photo comparison. (Man, it's freaky how close to comparison my car is to my buddy Steve's gtr)

I did see some mixed results online regarding the drag coefficients for cars. Does anyone disagree with the information I'm using from the actual wind tunnel? Ayone have additional data or opinions regarding the drag coefficients for different model years and styles of 3/S?

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the r35 gtr is actually very aerodynamic. it has a 0.27 dc. according to this site GTR has less front drag area than the NSX and NSX has a very narrow front and much smaller and lower car too. Automobile drag coefficient - Wikipedia, the free encyclopedia
if you look like some new cars the front bumper sides of the GTR is block but the center. the ducting to the brakes and oil cooler are all fed by the center opening. that's my goal to block any useless opening area on the front or have an exit. thinking to block the left side with licence plate and the right side to duct it outside of the car after passing through oil cooler.

this website is saying 3000gt's drag coefficient is .33 dc. not sure what year he's talking about, but would mitsubishi really make the car less aerodynamic as it get's newer face lift? the top speed never changed as far as i know so i'm guessing the drag was about the same.
Mitsubishi 3000GT VR4 Specifications

i have yet to see what 3000gt dc is from a valid source. people go from .32 on stealth and up to .39 on 99 vr4, but where did they get these info?

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Originally Posted by Julianvr4

Yeah that's a fail. Reverse NACA ducts are for show. NACA ducts are designed (back before many of us were born, mind you) to be a source of air induction with minimal drag. They do not work in reverse when you flip them around (to vent). No such thing. If you wanted to vent air out of the hood, you would want to get a JGTC hood, or get some low profile louvered vents and rivet them to your hood. (or weld them if you want it relatively seamless)


Welcome to the wonderful world of aerodynamics. I was hoping that I could wow some people when I get my car back in town and in my garage to fab up a front splitter, underbody tray, and a diffuser (basically make the car as slick as possible) but it looks like you guys are onto it already...My guestimations lead me to believe that 200mph can be had with 550HP and a very well designed aerodynamic package. It would just take a bit of sense and patience to get everything ironed out.

You want the front of the car as low as you can, and the rear can be less so if you have a flat underbody. That in itself would cause a pressure differential and you would get downforce out of it without creating any additional drag like you would from adding a wing. A front splitter will increase this effect if it is actually built correctly (IE: Angled down and matching the rake of the rest of the car, not that skillard splitter that just sticks straight out and looks goofy)

PS: Remove mirrors plz. The lincoln mark 8 ran 181 mph with under 300 horsepower back in '93 with MINOR aerodynamic mods.


oh yeah, and spend lots of time on Time Attack Forums. Lots of good information.
Also, check out mulsannecorner.com. Literal goldmine of race engineering.


EDIT: Oh yeah, at higher altitude you make less power because the air is thinner...but you also suffer less from drag because the air is thinner.

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i have searched and many people say they don't cause vacuum if revered but i have seen them revered on many race cars. the lexus there is also done by toyota.

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Originally Posted by RealMcCoy

A full weight Stealth that would run 10.90's and trap 130 at 3000 ft. elevation, (without the NOS) and you guys are telling me it didn't have the power to hit two bills...? And calling BS on Matt?

What the hell reason would Matt have to bullshit anyone...?

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A stock ZR1 runs a 10.7/10.8 with a trap speed of 130-135 all day long at 3000ft above sea level. Its top speed is 205mph on pavement, and 202mph on the salt flats at Bonneville. Its drag coefficient is lower than ours, the frontal area is equal. They produce 570whp +/-.

Now ask yourself this, how can a vehicle that produces similar power with near identical surface area and a higher drag coefficient go faster? Could you crack 200mph, maybe. Over 215, not just no, absolutely no. We need like 700 at the wheels to crack off 215+ with our Cd. That wasnt happening in 2001 man, sorry.

No one produced that kind of power until like 2004/2005. Look at the quicklist, 3si histogram, and dyno info Chris Hill manages. Matt didn't find his gold and develop capability till he came up with the T/3 kits. Those were one of the first kits on the market capable of producing 700whp and pushing trap speeds over 140mph. That's the kind of power you need to break 216mph with our cars. Clearly its apparent that didnt happen in 2001. Maybe it happened later, but not as quoted in having transpired in 2001.

This is 19ts all over again. Pencil pushing, over real world results.
http://i408.photobucket.com/albums/p...k/images-1.jpg

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i have searched and many people say they don't cause vacuum if revered but i have seen them revered on many race cars. the lexus there is also done by toyota.

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There's your answer. They work off of pressure differential. You want high pressure going to low pressure. It's the same way any airflow works. If you create a differential it will try and equalize itself.


Sent from my DROID BIONIC using Tapatalk 2

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Originally Posted by donniekak

This is 19ts all over again. Pencil pushing, over real world results.
http://i408.photobucket.com/albums/p...k/images-1.jpg

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In for stolen/swapped Dynosheet.......

Please don't derail this with speculation over someone did or did not do based on undocumented word of mouth. That isn't what this is about.

This is one topic I would have some useful input and insight about

Sent from my DROID BIONIC using Tapatalk 2

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If you create a differential it will try and equalize itself.

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True. But predicting where the lows and highs are, and how the flow gets from one to the other, turns out to be completely non-intuative and often works completely backwards from what is expected. More than one engineer has discovered his outflow vent working as an intake.

Not to mention the fun that comes from turbulant flow and vortex generators. Something that looks trivial - like maybe a windshield washer nozzle - might be in fact generating a vortex or upsetting flow farther down the car.

You can make general predictions with a reasonable degree of accuracy, but specific predictions about a specific part on a specific car require testing for validation.

Do I need to say that anyone attempting to drive 200 MPH on a public road is an idiot? Can we take that as a given?

DG

Of course it requires testing. In my case, a lot of trial and error at my school's runway since I do not have funds for wind tunnel testing or know of one close to me.

I might have been unclear about the reverse NACA duct. What I was getting at is that there are more effective ways to vent. The air pressure inside of the engine bay would need to be TREMENDOUS to overcome and power through the boundary layer of high pressure that's moving over the car's hood at higher speed (in order to get it to vent with a reversed induction device such as a NACA duct) If you put something directly in front of it with a sufficient profile to disrupt that boundary layer then I would see it working BETTER, but there are still more efficient ways to vent.

Sent from my DROID BIONIC using Tapatalk 2

There are some very interesting and informative comments on this thread. Let me toss out a few more thoughts for what they’re worth.

One of the ways we did areo work was to use coast down testing. We would take a car, get it to 120 mph, shift into neutral and then let the vehicle coast down to 20 mph. Record the decel curve with a data acquisition set up of some sort – we used a chart recorder in the old days but perhaps a more contemporary set-up would use GPS and a laptop program of some sort. As with any testing, repeatability and test criteria must be maintained or the data rapidly becomes unreliable – it turns to junk.

It’s a given that aero drag increases about the square of speed while tires are somewhat more linear but they too have a sloping curve of sorts. Other mechanical parasites might increase as speed increases but to what extent, it’s difficult to say with out some testing data. Obviously density altitude and wind have to be part of the aero equation.

The decel (minus accel really) curve will be most influenced by aero at the upper speeds while tires and other mechanical drag will have a proportionally greater effect at lower speed. After several runs, some thinking and a little math, you will probably be able to form a SWAG as to the effects of aero verses the other drag(s). You might not be precisely correct but you can still get a feel for what is going on.

After procuring some baseline curves, make an aero change then perform a few more tests to validate the results. Be advised that a single aero change might have an effect on the other constituents of drag. If the car is lowered a couple of inches in the front, it might reduce the front end lift at speed which means a greater load will be placed on the tires – hence tire resistance increases. As others have referenced earlier, one aero change might result in an upset or a benefit of aero somewhere else on the car.

You will probably be able to achieve a pretty good feel for aero at lower test speeds as well – my advice is do not even attempt 120 mph aero work on a public highway. Might be more prudent to use a top speed of say 75 mph and coast down to some other given speed. Even this is dangerous on public highways – my advice is to get on a track of some sort.

In other words, it is possible to use coast down testing instead of top speed testing to draw some conclusions about aero. Might take a little thinking but the confidence level is high that some posters on this thread can figure it out.

Good luck in your endeavor.

Jake -