RXASSASIN7

I dont know if this has been discussed before but my bother and i were having a conversation about how he took his porsche on one of our local highways and hit 185mph, the discussion turned over to my car were my brother said he was pretty sure that my top speed would be around 160-165mph based on gearing NOT horsepower. anyone know what a '93 rx7's gearing will let you go up to in speed (considering you have the hosrepower to bring it to that speed)?

RotorJoe

What he said was just about the top speed of a stock 7 will run, horse power limited.

I am not sure but I think the gearing will take you to about just over 200, that is just what I have heard.

I have had mine up in the 175 range. Backed out cuz I saw flashes of the Racing Beat car flying.

RXASSASIN7

i would imagine around 200 also but he said he didnt think so i forgot why he said though.

jeremyb

.... I was on highway 5 and hit 170, car was HELLA quiet lol (im stock). But I remember saying "omg that must suck" when I saw that clip of the 7 flipping and sliding upside down for a mile or two lol. So I let off the gas and 85 I went

Mahjik

iTrader: (1)

https://www.rx7club.com/showthread.p...ring+top+speed

maxcooper

As has been posted on here many times, the top of 5th gear with stock-sized tires is just about (a little over) 200 MPH at the 8,000 RPM redline. Also, this can be calculated with simple math -- it doesn't require someone to go out and do it to find out. You can get some concrete, first-hand evidence of the speed by driving in 5th gear at 4,000 RPM. Your speed at 8,000 RPM would be twice what it is at 4,000 RPM.

-Max

jsplit

So what you're saying is that the rpm increase is completely linear from 4,000 up?

turbojeff

iTrader: (30)

Actually for our purposes it is completely linear from 0rpm up.

If you didn't want to go 4000rpm in 5th you could get a little more "crazy" with the math. Say you went 2000rpm in 5th, you'd multiply the indicated speed by 4 and multiply the rpms by 4 and you get the miles per hour and the corresponding rpms.

Jeff

jeremyb

200 mph...

RXASSASIN7

okay okay so are we all agreeing that the top speed for gearing (even if you had a million hp to push it there ) it would definitly would top out at 200mph with stock gearing????????

RX7WEEE

iTrader: (16)

Yes.....

RXASSASIN7

i dont know that number just sounds tooo "rounded off" if you know what i mean. i need specifics. and resoning/ proof behind the number... it sounds like everyone is justr giving me a guess/ maybe an educated i dont know!

r0gu3

But if you take it to 9k ... :evil:

poss

iTrader: (5)

Or according to cartest, something closer to 500rwhp

SRA-FD3S

i've read 215

RXASSASIN7

did you read that number in a book or on a calculator?

cause your ride doesnt have a speedometer to read that kinda nuimber

scotty305

iTrader: (2)

according to http://www.mysportscar.com/tools/topspeed.htm , the gearing-limited top speed for my car with my tires is 199.26 MPH.

Tire Width (mm): 245

Aspect Ratio: 45

Wheel Diameter (inches): 16

Rev Limit (RPMs): 8000

Overdrive Gear Ratio: 0.719

Final Drive Ratio: 4.1


Tire Circumference (inches): [calculated 77.5]

Theoretical Top Speed (MPH): [calculated 199.26332862037057]

-s-

RXASSASIN7

you are THE man . thank you!

RXASSASIN7

heres what i got ! wow its just hard to believe my trans will let me string out that much?!!?!? dont you think?

Tire Width (mm): 295
Aspect Ratio: 45
Wheel Diameter (inches): 18
Rev Limit (RPMs): 8100
Overdrive Gear Ratio: 0.719
Final Drive Ratio: 4.1

Tire Circumference (inches): 89.38689342519684
Theoretical Top Speed (MPH): 232.58526509629306 mph

poss

iTrader: (5)

call me crazy, but I don't think you can fit 295/45/18s on your car.

maxcooper

The speeds at 2000 or 4000 RPM thing should be all the proof you need. That's why I mentioned it -- it is concrete, you-can-go-experience-it proof.

Any car enthusiast should be able calculate vehicle speed in gears, so here's a chance to learn if you haven't done it before:

Go look at the revs per mile on the spec sheet for a 225/50-16 tire (the stock FD size). Here's one:
http://www.tirerack.com/tires/Spec.j...omCompare1=yes

This one says 807 revs per mile. 5th gear on the FD is 0.719 and the final drive is 4.10. Redline is 8000 RPM. So...

Wheel RPM = 8000 / 0.719 / 4.10 = 2714 RPM

Vehicle speed = 2714 / 807 = 3.363 miles per minute = 3.363 * 60 MPH = 201.8 MPH

The tires would actually get bigger as the speed goes up, so this is a conservative estimate.

Note that some tire models give less revs per mile (because different tire models have different actual sizes, even for the same nominal size, and because of sidewall stiffness, etc.). I did this first with the S-03 and it had 837 revs per mile, which gives a top speed of 194.5 MPH with this calculation. But I didn't want anyone to freak out when the number came up below 200, so I chose another. I think some variation of the Yoko A022 that I chose actually was one of the stock tire models that came on the car.

-Max

RXASSASIN7

oh thats where i messed up thanks!!! i forgot to change that one

RXASSASIN7

okay my top speed would be : 204mph

thats more realistic!

Sweet

RXASSASIN7

okay my top speed would be 204mph

thats more realistic!
sweet!

jimlab

I think you meant optimistic.

Calculate your theoretical top speed in 4th gear and then go try to achieve it. I guarantee that you come up about 4-5 mph short unless you exceed the redline you used for your calculations, and the difference will be more substantial in 5th gear. Speedometer error, tachometer error, tires not being perfectly round when mounted on the car, and tire slip all contribute to ensuring that you'll never meet your "paper numbers", even if you do have the power required.

On that we agree. P295/45-19s would be approximately 29.4" tall when mounted, and the stock P225/50-16s are over 4.5" shorter at about 24.8" tall.