ExcelR8

If i was to take a stock, TT, 3rd Gen rx7 and get it converted to a 3 rotor.

What do yall estimate the top speed to be ??
I know the conversion makes it basicly a V12.

But i want to know around what would be the top speed of the car after that conversion alone.

Thanks.

BLUE TII

iTrader: (9)

Same as a built 13B as you are limited by gearing once you have some HP.
But, I imagine if you can afford to put a 20B in a 3rd gen you can afford to swap gear ratios...

ExcelR8

Aight.
What gear ration should I use ?

bkapold@aol.com

4:77's or 5:12's

ExcelR8

Ok. They are giving me a hard time in my other post.

I probably wont actually make it that fast and stuff but i'd like to know what price range i'm looking at.

Evil Aviator

They are giving you a hard time because:

1) You can't have it both ways. Build the car for the drag strip or the Nevada Open. Choose one and go with it.
2) The price on something like that is way out of the range of most people on this forum. You are looking at $15K for the FD, $35K for a professional 20B-REW conversion, and another $30-50K to make it fast. Yes, if you bought a car that already had a basic 20B conversion you could save a lot of money, but it's still going to be expensive.
3) Even if you can afford the car, it doesn't mean that you have the skill to drive it. It's going to take a lot of driving schools and racing events until anybody lets you enter an event where you can drive the car to its potential.

I don't mean to give you a hard time about it, but rather to explain why everyone else is.

BTW, for 240mph you are looking at something like a 0.5 6th gear with a 4.00 rear end, +/- depending on your rear tire size and power band.

PaulC

I think the 4.00 rear end would still be way too low to reach 240, but i dont have a gear ratio calc either just a feeling. then again there are only a handful of people who can truly push a car that fast safely. And having been on one professional racing team as a test driver. 99.9999999% of the people on this forum would scare me at half that speed. Im sure there are a couple of very good drivers out there so im not including everyone else. I wouldnt want to drive a car at 240 unless it was on te salt flats then maybe .......

Remember CART drivers bailed out of racing here in Ft Worth cause they felt 230mph was too fast to be safe.

ExcelR8

Aight,
What does the board think I should do ??
How fast do u think i should make it and what would it run in the quarter. U can do both because i've seen it.

Evil Aviator

OK, you are what, an E2? I think you should look around for a nice somewhat-stock FC which will pass inspection and is reliable enough to get you to work in the morning so that you don't get in trouble and lose your job. Use the money you save to take college courses and let the taxpayers pick up the other 75% of the tuition. Once you get your degree, then you can get a high-paying job which will allow you to afford an additional vehicle to play with. If you want to stay enlisted, then also stay single, and you will be able to afford something nice once you make E6. In the meantime, learn how to drive the FC at the local drag strip as opposed to the street where you will just get in trouble, and put all your spare cash into your IRA.

That isn't possible. The internet is at your disposal, so feel free to post a link to any top-performing drag car which also is a points leader on the road track, and then you can prove me wrong.

Evil Aviator

We don't need no stinkin' charts.

Speed in mph = (Rear Tire Circumferene in inches * Engine RPM)/(1056 * Transmission Gear Ratio * Rear End Gear Ratio)

Given:
Rear Tires = 225/50R16 = 78.095 in circumference (more or less)
Engine RPM = 6500rpm
Highest Transmisison Gear = 0.50
Rear End = 4.00

Speed = (78.095 * 6500 ) / (1056 * 0.50 * 4.00)
Speed = (507617.5) / (2112)
Speed = 240.35mph

PS: No argument about the safety issue, though.

ExcelR8

My girl is the one buying the car for me.
She carries 500,000 in her purse and had 4 million in the bank last time i checked.

Her parents were rich and they died.
Leaving her with cash.
Plus she models and sings on the side.
She just paid cash for a house that was 275,000 dollars.

We got the money to do it. And i'm going in as an E4 because i've taken advanced training because i'm going to be on a nuclear sub building the guidance system on nuclear missiles.

I go in as an E1 just like everyone else.
But my first check will be the same amount E4's make and when i finish boot camp i'll get promoted to E4 to begin my sub training.

But i've decided i dont have to do that. 200 is plenty fast. I'd rather work on appearance anyway.

j9fd3s

iTrader: (3)

my friends fd with a ported motor, downpipe, midpipe, n1 dual, and a power fc, will hit 8000 rpm in 5th, its like 180+. thats as fast as the car will go unless you change the gearing.

mike

Attila the Fun

iTrader: (1)

And I know just where you can save it: www.cris.com/~Asam/20B.html

With current gearing (4.10 rear end), the theoretical top end is 200 mph. Realistically, drag would limit that to around 175 mph, I believe. However, with some porting and a big single turbo, 200+ would be feasible. Peter Farrell estimated the upgrade at $15,000.

Attila the Fun

iTrader: (1)

Show her my website at
www.cris.com/~Asam/20B.html Even if you don't want the car, she might.

As I said in the other post, my car with a $15,000 upgrade should get you the 200 mph. Now that I think about it, budget $17,000. You'll need some new, high-speed tires.

bermuda20b

Gotta respond to this!

As I am one of the very few on this board that has driven at speeds over 200, let me share a few things on what it takes.

Tires - There are a whole raft of issues regarding tires...what are your plans?
Axles - I assume you will be getting hardened axles for the strain they will be under. Do you have a contact for the restraint system that will be needed to avoid losing a tire?
Diff - How are you going vent it?
Driveshaft - What type?
Tranny - what are you going to do?
Motor - easiest thing as it takes less that 500 RWHP to run over 200.
Aerodynamics - what are you going to do to the car...no the stock body won't work...how are you going to get rid of the excess air that goes into the engine bay? What kind of a diffuser are you going to use?
What kind of spoiler?
What kind of splitter?

You are going to need a budget of at least 100k. People don't realize the $$$ required to go from even 190 to 195 hp.

Paul C, my understanding is that the problems with Cart in texas were the result of G forces that were blurring their vision.

Just remember the following

-Speed
-Reliability
-Cost

You only get to pick 2 of the above 3.

We ran 197 in practice this past Saturday...did a gear change to the car for Sunday. Got 4 miles in and snapped the input shaft...sucks to be me!

If you are serious about building a top end car, PM me.

earl

PaulC

Ever here the saying a fool adn thier money??????

And 200mph in your hands ........ no offence stay off the roads my tax dollars are paying for. You obviously have not thought this through.


Navy Nuke program demands you to be the most **** retentive attention to detail person out there. And listening to you........... I'll let everyone else fill in that blank. And I speak as a former NCO that was let out on medical disability.

Jeff20B

iTrader: (13)

Evil, I sorta worked out how fast my Cosmo should go with enough power. I don't know what 1056 is for, so I left it in there.

(tire circumference x 6500RPM)
78.5 x 6500 = 510250
(1056?? x 'D' gear on an automatic x stock diff gearing)
1056 x 1.00 x 3.636 = 3839.616

132.89 MPH

I've read that CD Cosmos were pretty decent on the highway because the suspension was tuned for it, or something. I would have imagined it could do up to 120MPH, but 132 is kinda cool (and will probably be kinda scary).

Evil Aviator

It's a unit conversion factor:

1 hour = 60 minutes
So, 1 rpm = 60 revolutions per hour

12 inches = 1 foot
5280 feet = 1 mile
So, 1 mile = (12 inches * 5280 feet) = 63360 inches

So, to convert from inches (tire circumference) and rpms to miles/hour, we get:
(60 revs per hour / 63360 inches = 1 / 1056

Evil Aviator

Do you mean the stock 20B auto transmission? I think that 4th gear was 0.694. Anyway, based on the large number of broken axles on my friend's NA 13B RX-3, I would give the stock CD Cosmo drivetrain about 3 seconds with a 20B, LOL.

Also, the stock 20B redline is 7000rpm, so you could go a little faster if you think the engine can take it.

Jeff20B

iTrader: (13)

In that case, at 7k RPM, it could get up to 143.11MPH!

The stock CD parts, according to Cal at: http://www.geocities.com/mazdarx5/ can handle 400HP from a turbocharged 13B, so they should be able to handle a 20B, for a while anyway. Its top gear is 1.00 and the diff and axles haven't broken on Cal yet, as far as I know. His website is under construction.

Evil Aviator

You may want to verify the strength of the Cosmo drivetrain on the Single-Turbo forum or maybe at one of the Anzac forums. I really don't think that it can take all that torque.

Hehehe, 143mph is good.

BTW, I just used 6500rpm as an example in my post because the rated peak hp of a stock 20B is at 6500rpm, and that hp is going to be needed to fight off all that drag at 240mph. Of course, it depends on how you build your engine, your mileage may vary, batteries not included, etc. This is why I like to post formulas instead of just my opinion (which you get 99% of the time).

Jeff20B

iTrader: (13)

Yeah, I'll definitely ask around and do my homework before undertaking this project. I'll be starting out NA so I'm not too worried. I'll upgrade the drivetrain components as they need it/break lol. I want the torque and sound of a 20B. I could get torque from a properly setup 13B, but the sound wouldn't be there. This project is at least 50% for the sound of a 20B, because I am obsessed

Anyway, I appreciate your input to this forum, specifically because of stuff like this. You're not doing a Banzai, and neither am I, so sharing info is all we can do. Especially when it's about our experiences performing all the custom work required to make our cars into something that Mazda should have done originally.

bermuda20b

excelr8/Joe Harrison, or whatever your name is.

Why do you post that your girlfriend has 500 k in her purse and that she is buying you a car yet you ask me if I will finance the car.......

j9fd3s

iTrader: (3)

maybe they broke up?

mike

cmartinp28

well, about this top speed thing......... i dont know of anyone(other than professional drivers) who would need to go 240 unless the salt flats is in your back yard and you have enough money to do it