CHEF_EG_1

Ok... as many of you should know, I am making a 4-rotor First Gen RX7, to go n/a, and carbed, to break the land speed record for a rotary.


However... other than the obvious aerodynamics and hp concerns, comes something that was a hindsight of mine until I began planning out exactly what parts to start buying....



What distributor am I gonna use? Keep in mind, this is for a 23A, essentially two 12A's sammiched together. How will I hook up the second one, if at all?



How will I get enough fuel delivered at 200+mph? I've heard horror stories from Bonneville teams, Nascar teams, F1 teams, etc., about how fuel starvation at such high top end speeds is such a crisis.

I was planning on running two 255lph fuel pumps, to give the engine enough juice. Also keep in mind, that while I will be bumped into a different class, I will more than likely be spraying nitrous.... LOTS of it. a 200 shot on each carb (there's 2 carbs) to spray at the same time. The fuel has to match it.




So, fuel and ignition stuff is the worry of the week this weekend, so feel free to post away!

rotary emotions

Well, that's a bit of a problem you've got there...
I have no idea about rules or anything, but wouldn't it have been easier to go EMS? With twin carb you'll need to get very proper synchronisation... Well, that's the smallest problem, the ignition is more complicated.
You could look into an old RX2 front cover, as this uses twin-dizzy's. Maybe they can be replaced by two 12A ones. One for each half of the engine. I don't really know, it's just an idea. Maybe it's also possible to convert a 12A distributor for four rotor use, much like Racing Beat does for 20B aplications. Again: not sure, just an idea.
Since the engine is basicly a double 12A, the 1st and 3rd rotor, and the 2nd and 4th will probable do the same thing at the same moment, right?
Couldn't one distributor trigger two DF units?
Still, I believe programmable EMS (ignition only, does that still excist?) would be easiest...
Not sure if I helped you a lot, but well, at least I tried

RotorMotorDriver

iTrader: (1)

Distributor? Whats that? Direct fire .

~T.J.

JEC-31

I think that rotary emotions might be on to something. If your firing order really is two sync'ed 12as then using a single 12a dizzy to trigger some sort of massive dual sparkage is a path to investigate...
What will your firing order be?
What RPMs are you looking at?

On the carb issue, what kind of carbs? A row of Webbers like the old Bonneville flatheads? That would scream! Or dual Holley double-pumpers like some monstrous Pro-Street beast? You're going to need a gallons-per-second fuel supply alright.

Manntis

for the money I still suggest a 3-rotor (parts already developed) along with suspension tweaks to effectively put that power on the pavement, even in corners, and a budget left over to make sure all the niggling little stuff (switches, door and hatch rubber, interior trim, etc) is worthy of the car.

I'm still wondering why you'd spend tens of thousands on a custom engine, yet not spend $500 on a rust free shell...

rotary emotions

I wonder why carbs??? Look at 3rotor.com, he has a four rotor turbo under construction...

JEC-31

I get the impression that Chef seeks to drive the path less traveled. A nitro-huffing carb'd 4-rotor stuffed into a rust-repaired FB means pretty much bazing his own path.

I would start with a clean shell, too, and spend no more than $100 plus gas to go get it. But the one cool thing about a rusty shell is that you don't feel bad about modifying the heck out of it, like tube-framing, roof chopping, channeling, all the things that one might have to do in search of high-speed areodynamic stabilty.
This assumes you also don't feel bad about 10,000 hours of body work.

CHEF_EG_1

The free shell has now become the parts car for my 79 widebody.... the "shell" has a full interior in great condition, and other misc. odds and ends that I will need to swap over to the widebody to a)make it road worthy, and b)make it ~complete. The free shell, after seeing it, is nothing more than a parts car at this point.


I have seen some pristine shells (even one with the 2" chop that I want!), and for fairly cheap. I wasn't prepared to BUY a shell, per se, but after seeing the free one, I really have no choice.


And as far as the 20B concerns... yeah, it's a tried and true engine, but with the right hookups, and the right buildup, it [the four rotor] is gonna be indestructible, in theory.

Manntis

in theory, bumblebees can't fly

JEC-31

Chef, what will you call this motor: a 12AA or a 24A?

i_piss_on_hondas

http://www.grannysspeedshop.com they built a 4 rotor... I talked to the guy who built it on the phone he is a really good guy... ther are a few companys makeing 4 rotor e-shafts now... I think it would be a good idea to use a twin distributer front cover... as far as carbs go get a large tpi setup... you will make more power with a fuel injection setup... or you can run twin throttle bodys...with some free flowing 4 bbl intakes... and run a aftermarket fuel computer...

Project84

What class you going to be in at Bonneville? I know its a ways away, but I have list of all the records for all the classes and I just wanted to see what you will be trying to break.

What size fuel lines are you going to be using? carbs don't use nearly as much pressure as with EFI. You will have to make sure you have a good volume of fuel supplied by the pump. Next, the plumbing has to be able to carry that fuel to the carb. Then the carb has to be able to deliver it without flooding. And where do you plan to tap the fuel system for your nitrous injection?

CHEF_EG_1

JEC, it will be called a 23A. a 12A is 1.15L. 1.15x2 = 2.3L, hence, 23A.

i_piss_on_hondas, granny's has been called a couple times, but with no conclusive answers yet. they want more questions when it's actually underway, rather than on paper. and WHO is making 4 rotor e-shafts, and how much? links? phone #'s?


will answer more questions in the morning.... very seepy.

rotary emotions

I'd like to know who's making 4-rotor e-shafts too. And the price...

i_piss_on_hondas

WEll if I tell yeah your going to have to call it the " I **** ON HONDAS" I comp it out of nz I know there makeing them... I think there is also one out of nz... I dont have the links any more to either of those too... Hurley MIGHT I am not shure if they do or not... I cant get there web site to work but there ARE companys out there that are makeing there own 4 rotor e-shafts...

i_piss_on_hondas

**** I ment also a comp out of austrailia

CHEF_EG_1

I may have an available option for the igniton and distributor stuff....




MSD High Output Distributorless Ignition System

Manntis

won't you need a digital dis-8, for 2 plugs per rotor x 4 rotors?

CHEF_EG_1

....and the fuel delivery....



Aeromotive A2000 Drag Racing Fuel Pump 350gph

CHEF_EG_1

wouldn't 2 digital dis-4's work the same?

Junia

I have an old "RX-7 Magazine" from Japan that has an article on the 4 rotor motor and I know that it discussed the firing order and problems encountered like the e-shaft snapping and stuff. I'll bring it into work and scan and translated but that won't be until tommorow.

Maguire

iTrader: (1)

To me, it seems like you would have too. Since the trailing doesnt fire opposite the leading. I don't think the dis 8 would work. But, what do i know?

RacerX7fb

A buddy of mine already has made a 4 rotor built from 12A parts. He's on his way to Kentucky to pick up an FD shell to put it into. The engine has a custom machined eccentric shaft and will be turbocharged: http://www.autotechmotorsports.com/projects-4rotor.htm

Manntis

how would you synchronize the 2 dis 4 digital boxes?They'd both have to receive the same engine speed signal yet respond at different times.

Maguire

iTrader: (1)

Hmmm.... is there a way to send the signal from the first box to the second box, but delay it? Just a shot in the dark. There has to be a way. How would to propose to use the single box over the 2?