DCrosby

You could be my dad and I wouldn't let you hold that wheel @ that speed !!!

$150FC

edited my post, heh. Camera is what i meant, not wheel.

|aFk| LiMiTz

damn racing beat said that they were shooting for clost to 300 mph but had bad conditions on the salt flats wow

http://racingbeat.com/FRphotos.htm

Fred Sickert

There is a calculator here
http://www.rx7turboturbo.com/robrobinette/top_speed.ht

Here's an equation for hp needed to overcome drag:

Aero Horsepower = 0.000007 X Frontal Area(sq ft) X CD X Speed3 (Speed to the 3rd power)

If you could improve the cd and/or reduce frontal area by 10% and had ~470 flywheel horsepower you should make it.

JONSKI

Thatoneguy's avatar is a pic of him going about 180. I don't suppose anyone can post a link to the larger image, can they?

RxSeven1

iTrader: (2)

that one pic is on a dyno

RxSeven1

iTrader: (2)

bigger

Black Magic

iTrader: (2)

at 300 RWHP at 7500 RPM in fourth i was at 165 MPH. Still some more till redline, so maybe 170 in fourth,, then maybe 5th could bring 200. I wouldnt know how close to 200 i could get, my engine say F-U after 165mph
o, and stock 4.10 rear 245/45/16 tires.

Benjamin

There's a video of me, err...someone... doing a 170mph flybye on here somewhere, but I'm not sure where. Someone PM me to host the video. It's available on the RX7 revolution DVD from the 2003 event. We played it the next day in a Hooters party room with 100 rotorheads, and was witnessed by a 7 car caravan (in addition to the video). The car was still pulling, and was at about 330rwhp.

-BN

|aFk| LiMiTz

I think I have seen that vid as well, was it the silver FD that was doing about 170...and another fd next to it doing about 120 and got passed really quickly

jimlab

165 mph in 4th gear with the stock 4.10 rear, huh? Better check again... 4th runs out at about 140 mph.

911GT2

This is directed mainly at Jimlab, but others can feel free to reply to.

I understand that wind resistance will eventually overcome the available horsepower, and the car won't be able to accelerate any further. Thats cool, I think everyone gets that.

But that doesn't change the fact that the engine is spinning at 8000 rpm, which in turn spins all the tranny internals at X rpm, and spins the wheels at X rpm. Theres no conceivable way that air resistance can change that.

I know that at very close to 80 mph, my engine is at 3050rpm. A quick calculation (using MY own stock wheels/tires, and tire pressures etc) yields a speed of 209 mph at 8000 rpm. Theres no way I can see that air resistance could change that. This assumes of course that the engine has the power to push it that far.

Cliffs Notes: Assuming the engine has enough power, air resistance can't affect the speed of the car at a given rpm in a given gear.

t-von

iTrader: (8)

Come on guys! The rear tires could have easily been put on jack stands and maxed out in 5th to get those numbers or a dyno. I've done it before.

Benjamin

That would be the one Here it is. Um...it's not me...

It's way better to listen to with sound. And there are a few other entertaining video's in there as well, from the same trip. In the 'autocross' video, it doesn't seem like it, but we were going 60+ mph, with meiogirl's BF filming.....

-BN


http://www.stlrx7club.com/rx7revolution/videos.htm

jimlab

Actually, there are several factors conspiring against you attaining a theoretical top speed besides air resistance...

1. The inherent inaccuracy of analog gauges
2. Tires are not perfectly round
3. Tire slippage

If you don't believe me, calculate your theoretical top speed at redline in 3rd gear and then go try to achieve it on the road. Obviously you should have enough power to reach redline in 3rd, but where did those last few mph go??

fastcarfreak

i was going to say the same thing!




that still doesnt explain how theoretical top speed at a certain rpm in a specific gear with specific gear ratio is changed by wind.

Vegas84RX7

here...is the video...

Zero R

iTrader: (1)

The "theoretical" top speed hasn't changed it's "theoretical"
Real world top speed will be affected by real world things such as drag, and honestly if it was a "theory" with any type of real science behind it it would have put some type of drag in the calculations just to be as close to accurate as possible. I think it should be more apptly called mechanical top speed.

jimlab

It is more commonly referred to as "gear-limited top speed".

With no air resistance and no frictional losses from the road surface, a car could probably achieve (assuming the actual circumference of the inflated and installed tires were used in the calculations) its gear-limited top speed.

In the real world, however, pushing air out of the way consumes horsepower. The faster you go, the more power is required, and even though you can overcome the air resistance by adding more horsepower, you can't eliminate frictional losses or tire slip, and therefore a vehicle's actual top speed will always be less than its gear-limited top speed. Always.

RotorMotor

iTrader: (5)

or even better, have you ever dissasembled a gauge set before? if you rotate the speedo needle clockwise past 12 o-clock it will fall to where you see it now.... then put it back in and just rev your engine in neutral.... looks like your doing 190 heheheh