my 200mph rx7 build

[turbotoaster]

Ooo a T04, thats quite a cheap turbo for the power its rated to my old style T88 is rated to 850bhp for piston engines, probably only good for 650 on rotaries lol

What power are you looking for?

I guess this would help with what diff ratio you need:

http://www.kabamus.com/garage/gears.html

What extra mods have you done to the engine, box and drivetrain? Did you get the engine doweled?

to hit my target i need a minimum of 630bhp, the more i have above that the better.

the engine isnt doweled as ive seen a few that have cracked there plates from it, the box is stock, im not doing any 0-60s or drag racing in, theres a fd in usa thats running 700bhp on stock box and he drag races his, runs 9s at 145mph on low boost!

[shaunwil]

Out of interest won\'t bigger gains also would be to streamline the car even more and get drag down to an absolute minimum. How much material is needed to sheet over the floor of the car .

Is the 630bhp based on a drag coefficient of the profile of a standard car ?

Shaun

[shaunwil]

Other questions is where are you planning on trying to hit 200mph ? Are all the standard suspension components designed to cope with 200mph ? Will the car undress itself at that kind of speed. What safety kit are you going to use when making the attempt ?

Its definitely an interesting project.

Shaun

[Nik da Greek]

Other questions is where are you planning on trying to hit 200mph ? Are all the standard suspension components designed to cope with 200mph ? Will the car undress itself at that kind of speed. What safety kit are you going to use when making the attempt ?

Shaun

Very good points. What are you gonna do to stop this happening?

http://www.youtube.com/watch?v=CNYIjG3se3I

And what are you gonna do when it does?

[m1tch]

Other questions is where are you planning on trying to hit 200mph ? Are all the standard suspension components designed to cope with 200mph ? Will the car undress itself at that kind of speed. What safety kit are you going to use when making the attempt ?

Its definitely an interesting project.

Shaun

I think getting the power and the parts together will be the easier bit, its a bit like when James May took the Veyron to its top speed, yes it could do it, but it was a bit of a faff to actually do it.

[Jit]

Few points id raise

1- safety - i assume you are going to put a roll cage in? An FD feels floaty at 145mph! I dont want to imagine how it feels anywhere remotely close to 200.

2- gearing - I cant see how a standard auto diff is going to be enough. By my calcs, an auto is geared to 170ish if it had the power. Its not even a simple case of changing the 5th cog either. I imagine you would have to run some sort of hilux or ford rear end?

3- power. I would say you arent going to do it with 650 either. 650 is just enough theoretically to overcome aerodynamic drag. Rolling resistance will be pretty high come 200mph. If it were me, id be running some sort of tall rear wing to keep the back end down and thats going to increase aerodynamic drag greatly due to its shape and i imagine an increase in drag induced by the negative lift around it

Finally youve set yourself a target of doing this on a 2 mile straight. If youre lucky you might be doing 140 at the half way mark. That leaves you 1 mile to go from 140 to 200 and stop

Oh yeah thats my final point - you might want to install some proper brakes!

[m1tch]

Few points id raise

1- safety - i assume you are going to put a roll cage in? An FD feels floaty at 145mph! I dont want to imagine how it feels anywhere remotely close to 200.

2- gearing - I cant see how a standard auto diff is going to be enough. By my calcs, an auto is geared to 170ish if it had the power. Its not even a simple case of changing the 5th cog either. I imagine you would have to run some sort of hilux or ford rear end?

3- power. I would say you arent going to do it with 650 either. 650 is just enough theoretically to overcome aerodynamic drag. Rolling resistance will be pretty high come 200mph. If it were me, id be running some sort of tall rear wing to keep the back end down and thats going to increase aerodynamic drag greatly due to its shape and i imagine an increase in drag induced by the negative lift around it

Finally youve set yourself a target of doing this on a 2 mile straight. If youre lucky you might be doing 140 at the half way mark. That leaves you 1 mile to go from 140 to 200 and stop

Oh yeah thats my final point - you might want to install some proper brakes!

And a main and reserve chute

[shaunwil]

I thought the auto diff was good for 237 ? I\'m sure kev had a cosmo friend in NZ doing some mental mph !

This thread is raising some very interesting questions !

Plus the speedo is terrible past a ton, its just is far too optimistic.

Shaun

[Jit]

sorry my bad, i hadnt changed the rev limit! a stock FD box with a 3.9 auto final drive should theoretically be geared to 187 ish on an 8000rpm redline. I imagine thats what ant from sterte garage ws running when he did his 180 something mph run.
It is possible to get to 200mph on stock box and auto diff IF the engine will rev to a touch over 9000.

[shaunwil]

Just looking on mazdatrix and the FD box has the longest 5th / 6th gear too so there wouldn\'t be any easy box swaps.

Shaun

[Jit]

lol! i was just doing the same checking if an RX8 box might do it but alas its geared shorter than the fd.
So gearing wise, itll either need a much taller diff which will hurt acceleration and increase the likelihood of running out of runway or a different box. Just looked up supra 6 speed and I dont think thatll do it either!

[turbotoaster]

the car will be going to bruntingthorpe, the power is based on coefficient of worse cars than the rx7 to be honest, that and a little bit of input from a 650bhp porsche that did 211mph in the same distance ive got(2miles)

there are no plans for aero work, though i may remove the rear spoiler as it adds no downforce and only drag, ill also remove the windscreen wipers and mirrors, thats it

people are forgetting about changes in tire sizes aswell, your saying it cant be done, funny how a 670bhp 4x4 escort cosworth did it, and a 650bhp 4x4 corolla aswell, ive already dont a gps 156mph and felt fine, i know 200mph is different but im doing in a straight line on a ride runway, cant get anymore safer.

i spoke to the guys at racing beat, he lost control because he spun the rear tyres at 220mph, salt is different than tarmac

[lee mills]

so there are a lot of guys on here with around that sort of bhp why doesnt somebody slap a auto diff in and see what happens? Everybodies questions will be answered one way or another:Laugh Apart from whether it can be done for £10000

[turbotoaster]

why dont you go for it, you have a big power car, wanna beat me to the prize?

[lee mills]

Ive no intentions of going for it.
Just thought it was raising a lot of questions and by your own admission it  will take you a while to be able to afford to finish your project so maybe some of the questions raised about gearing could be answered for you.