speed limiter

GPXXX · Post by **GPXXX** » Tue Feb 03, 2004 5:51 am

Where's Jerry Springer when you need him...LOL

seriously I have given this thread a lot of thought all night (yes, i do have to work at 4am in the morning believe it or not..!!) and because there is quite a bit of technical aspects to be gained from this discussion, i feel that it is not necessary to escalate things any further because technically speaking in general this is no doubt a very useful thread for future references.

I did not want to get involved into the middle of this debate but seeing how Steve got a little 'concerned' with the issue at hand, I figured the situation must be in worse shape than I first thought so like it or not, here's my 2c (hopefully my last on this matter):

What surprised me most is to see how far each of you were willing to go to prove your point(s), particularly in some cases maybe just a little further than necessary... In reference to the subject matter, I cannot say who is right or who is wrong because technically I am not qualified to make that call but I'm pretty certain that the argument got out of hand over petty little issues...

In light of some of the 'colorful' responses we've been seeing, this sort of debate is expected especially being on an Internet-based forum because there will always be mixed opinions and ideas so please bear in mind that written language is entirely different to body language because how you express yourself in writing (even with the best of intentions) can be interpreted in many ways and unfortunately sometimes the wrong way as well...

What i'm really trying to say is try to appreciate & respect each other's differences... a little bit more of tolerance would also help but calling each other names or constantly refuting/rebutting comments on a personal level especially on a public domain is not how this club works... the forum is here for a reason, and that is to learn and enjoy, not provoke and argue so please let's make the best out of it, are we cool??

OK it's past 5am now, I didn't even have my regular fix of Red Bull to last me for the night and i think i may be clinically brain dead right now (judging by my gibberish after spending more than an hour constantly proof-reading & retyping this post let alone the fact that I am running out of words on my vocabulary) so I'm just gonna shut up now and get back to sleep until my shift ends at 7am...

So why not we just call it a day, move along, grab a nice little' cuppa and enjoy more of my 'quality spam' instead, shall we?

(oooh look, i can see the morning sunrise...!!

)

"Take care of yourselves, and each other..."

Theremin · Post by **Theremin** » Tue Feb 03, 2004 10:39 am

Ruchi - I think your estimate of CD (0.33) is conservative, but your estimate of frontal area (24 ft2) probably a bit high. See here for some comparisons:
http://www.teknett.com/pwp/drmayf/dragcd~1.htm

Overall though I think you're on the money.

ruchi · Post by **ruchi** » Tue Feb 03, 2004 11:02 am

GPXXX · Post by **GPXXX** » Tue Feb 03, 2004 12:51 pm

dannyboyau wrote: but if anyone knows where to get a 300 km a hour speedo for the FTO i will test it

maybe I could entice you to purchase one of these??;)

Defi Concept VSD

Comes with tacho and speedometer as standard, and I'm pretty sure it can read up to 9500rpm and 400km/h respectively... (with additional modules that you can plug in when desired)

Specs can be found here ----> http://www.defi-shop.com/product/concep ... _spec.html

For a brief demo, click Play on the following link ---> http://www.defi-shop.com/product/concep ... oncept.swf

dannyboyau · Post by **dannyboyau** » Tue Feb 03, 2004 11:06 pm

http://www.theautochannel.com/content/v ... p9621.html

link to to the 1996 eclipse c/d 0.29

dannyboyau · Post by **dannyboyau** » Tue Feb 03, 2004 11:11 pm

the cd for the electric FTO is taken from a mitsubishi document

http://www.mitsubishi-fuso.com/ECO-E/re ... 0e_2-2.pdf

dannyboyau · Post by **dannyboyau** » Tue Feb 03, 2004 11:16 pm

ruchi wrote:WOW! a CD of .22 is EXTREMELY low, I know of no other car that even comes close to that, even the likes of the McLarens and Ferrari's are high 20's or low 30's.

http://www.amo-automotive.com/amo/articles/20020923_GM

seems you dont know everything then

notice the similarity in the front on view to any cars we know

dannyboyau · Post by **dannyboyau** » Tue Feb 03, 2004 11:21 pm

here is a four door sedan with a c/d of 0.27 with areo kit 0.26

http://www.caranddriver.com/article.asp ... le_id=1892

Post by **smorison** » Tue Feb 03, 2004 11:24 pm

danny
you've made your point, now lets move on.

dannyboyau · Post by **dannyboyau** » Tue Feb 03, 2004 11:39 pm

yea but steve i got a lot more examples i can post

i resent the implications made by ruchi that i am lying

Post by **smorison** » Wed Feb 04, 2004 12:31 am

i understand that you both feel injured by this whole exchange but there is no point in continuing it. if you would like to could i recommend you do it via private messages or email.

i personally was unaware (until now) of a production car (not a performance car like a lambo) below .29, and i spend quite a lot of time looking at cars and trying to steal ideas to put into mine.

feel free to continue (both of you) but please leave the personal remarks or attacks or attitudes out of it cause i'm really interested in the conversation so far.

incidentally i think you'll find the FTO has a fairly low drag reading, i draw this from a report where they tested the spoiler and it created no downforce (or virtually nothing). i believe its purpose is actually to funnel the air out off the rear of the car reducing drag rather than creating downforce (the downside is that the car is then restricted at cornering as it has to rely on mechanical grip) i will try and find the article cause i may be misquoting here. by reducing the drag created you may be able to reach a higher speed than what is test earlier in this thread with mathmatics.

Drag is not just a factor of what you are pushing but what you are pulling, infact DRAG is directly related to what is being pulled along by a moving object. believe me i study drag and ways to reduce it to get fractions of knots extra speed out of the sailing boat i race. you guys are looking at km/h and ten's of km/h where i focus on trying to extract speed in tens & hundreds of metres /hour (well its an easy measurement to use as an example), if i could extract half a knot advantage i would win every race.

If you can make an object detach itself cleanly from whatever it is passing through you will reduce its drag. common ways of doing this are slanted boots (i.e. the FTO's boot), smooth lines that follow airflow, reducing areas where the air/water pool up behind an object. reducing the vortex created from an objects trailing ends (example the wing tips on a 747-400 reduced the drag by 11% and increased power - actually lift - reducing fuel consumption and increasing flying time saving ten's millions of dollars per year for airlines).

The only way to accurately measure the drag and CD of an object is with a wind tunnel.

anyway i've had my say, i hope i've given you guys some more to think about and i hope we can all play nice in this wonderful sandpit

dannyboyau · Post by **dannyboyau** » Wed Feb 04, 2004 12:31 am

Rolling Resistance - vehicle weight x 0.013
So a manual FTO, with driver and fuel would be 2750lbs x 0.013 = 35.75lbs

Air Resistance (CD) - fA x Cd x 0.00256 x speed squared
fA is the frontal area of the car, approx 20' squared on a FTO
CD we estimate to be 0.28
speed - whatever speed you wish to calculate at

Based on 290kmh (180mph), the maths would be:
20 x 0.28 x 0.00256 x 180 x 180 = 464.4864 lbs

Power (HP) - Total drag x mph / 375

total drag (rolling resistance + air resistance) = 500.2364lbs

500.2364 x 180 / 375 = 240.11hp at the flywheel

now i am assuming that these calculations would normally be for a rear wheel drive car and a front wheel drive car has less losses in the drive train. So thus more power would be getting to the wheels then in a rear wheel drive car

lets try the electric FTO

damn dont have the wieght for it so we will give it the same as a normal FTO though i have no doubt5 they would have lightened it where possible but a bank of batteries does wiegh quite a bit

Rolling Resistance - vehicle weight x 0.013
So a manual FTO, with driver and fuel would be 2750lbs x 0.013 = 35.75lbs

Air Resistance (CD) - fA x Cd x 0.00256 x speed squared
fA is the frontal area of the car, approx 20' squared on a FTO
CD we estimate to be 0.22
speed - whatever speed you wish to calculate at

Based on 290kmh (180mph), the maths would be:
20 x 0.22 x 0.00256 x 180 x 180 = 400.7036 lbs

Power (HP) - Total drag x mph / 375

total drag (rolling resistance + air resistance) = 500.2364lbs

400.7036 x 180 / 375 = 192.33772 Hp at the flywheel

well maybe the front spoilers are not just for looks, well i think i can say that we will all learn a little from this post if we read it all.

so it is deffinatly worth reducing your coefficent of drag which can be done by lowering your car adding the apropriate front spoiler and reducing wieght of car, side skirts that come closer to the road, and shape of the rear end, which coincedently ( hope i spelt that right dont want people picking on my spelling ) the FTO has a very good rear end for recucing drag.

Post by **smorison** » Wed Feb 04, 2004 12:37 am

dannyboyau wrote:so it is deffinatly worth reducing your coefficent of drag which can be done by lowering your car adding the apropriate front spoiler and reducing wieght of car, side skirts that come closer to the road, and shape of the rear end, which coincedently ( hope i spelt that right dont want people picking on my spelling ) the FTO has a very good rear end for recucing drag.

i'm just happy i said it first

(or at least i think i did)

dannyboyau · Post by **dannyboyau** » Wed Feb 04, 2004 12:43 am

ruchi wrote:Thanks Theremin, that info was very useful.

Re-working the figures, based on a CD of .36 and a frontal area of 20ft squared (based on the figures from the other sports cars in the link Theremin provided), the horsepower required to reach the theoretical top speed of just under 295kmh, would be 302HP.

Keep in mind, these figures still don't include driver or fuel, which would probably add around 250lbs to the calculations, meaning you would need even more HP.

i know i shouldnt do this

but i noticed in this thread that so ruchi could keep his Hp figure at 300 he pushed the drag up to 0.36

i would love to know what the drag of the FTO is but i expect it would be a lot lower than that

also my car is a nakaya tune model ltd edition only 300 made with a couple of extra mods to it.
I believe in japan it would be like the HSV holdens are here, i dont have Hp figures for it but it would be above that of a normal GPX

dannyboyau · Post by **dannyboyau** » Wed Feb 04, 2004 12:44 am

smorison wrote:
dannyboyau wrote:so it is deffinatly worth reducing your coefficent of drag which can be done by lowering your car adding the apropriate front spoiler and reducing wieght of car, side skirts that come closer to the road, and shape of the rear end, which coincedently ( hope i spelt that right dont want people picking on my spelling ) the FTO has a very good rear end for recucing drag.
i'm just happy i said it first

(or at least i think i did)

well you got it up first i was actually in the process of typing and hadnt seen your post yet

so we call it a tie

Post by **smorison** » Wed Feb 04, 2004 1:21 am

dannyboyau wrote: well you got it up first i was actually in the process of typing and hadnt seen your post yet

so we call it a tie

you don't like to loose do you

GPXXX · Post by **GPXXX** » Wed Feb 04, 2004 1:21 am

dannyboyau wrote:so it is deffinatly worth reducing your coefficent of drag which can be done by lowering your car adding the apropriate front spoiler and reducing wieght of car, side skirts that come closer to the road, and shape of the rear end, which coincedently ( hope i spelt that right dont want people picking on my spelling ) the FTO has a very good rear end for recucing drag.

now i can feel proud that my front spoiler / splitters are not just for rice factor

dannyboyau · Post by **dannyboyau** » Wed Feb 04, 2004 1:31 am

smorison wrote:
dannyboyau wrote: well you got it up first i was actually in the process of typing and hadnt seen your post yet

so we call it a tie

you don't like to loose do you

i thought that was made obvious by what i have done to my car