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

[mb3000]

^^ Exactly what I was suggesting earlier.

[mehrshadvr4]

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 .

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 .

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?

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?

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.

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.

[J. Fast]

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...?

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.

[donniekak]

This is 19ts all over again. Pencil pushing, over real world results.

[Julianvr4]

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.

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.


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[whitedragon]

This is 19ts all over again. Pencil pushing, over real world results.

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

[Julianvr4]

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

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[DG]

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

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

[Julianvr4]

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.

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[jake stealth]

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 -