Most exciting car thing in awhile

[94touring]

Well, aside from getting my mini back on the road after a fluke wheel bearing failure.  Or Dave getting my bottom end built on my fast road 1275.  Rx7 turbo upgrade!  I'm swapping out the non divided 81 housing for a 1.0 divided housing.  I previously dynoed 405rwhp, but the smallish exhaust housing chokes power on top end.  Then I started digging into benefits to twin scroll turbos (I have a twin scroll manifold to reap the benefits) and I can expect a pretty significant gain through the whole power band.  Sounds like any lag associated with the larger a/r will be offset due to the twin scroll as well.  I use to run a 62-1 way back in the day with a 1.0 p trim and it would light them up in 3rd gear.  I now run a pt6266.  Figure I might as well go open dump wastegate like I use to run on the race rx7 and squeeze another 20hp out of it too.  All this to say, I got into a street altercation with a c63 amg Mercedes  (the 500hp turbo v8 kind) ane we tied.  The next time I see this guy he's going down hard. 

[MiniDave]

Man, and I thought it ran pretty damn hard already!   71.gif

[94touring]

Previous owner has the exhaust choked up pretty bad.  Turbo housings aren't expensive luckily, and the open dump wastegate is just me welding up where it's plumbed into the exhaust.  Most guys tie it back in for noise, but wot all the way to redlne is loud as hell to begin with.  I'll be loud and sound like a super bike all at once now.  Regular cruising won't be affected.  I anticipate a 50hp gain at peak and significant improvements from 4000rpms all the way to 8k. 

[Dmulder]

Is this an rx7 or a mini. Old rx7 or modern version

[94touring]

A 94 rx7. 

[Jims5543]

Two words:

Nitrous oxide

I had a 50 shot on my RX7 (a wet setup, the kind that sprays extra gas with the N20) and I am here to tell you it makes a Turbo Rotary into the Incredible Hulk.

While being Jetted for only 50 more HP, my ass dyno and racing against friends results leaned more towards 100 more HP.  When I would be neck and neck with a fast car without the N2O when we ran again with it on, I would be 2-3 bus lengths ahead. It was insane!!

Why? Because it is COLD and rotaries love cold, turbo rotaries love cold even more.  Bonus, make a trick setup where you have a second 1-2 gallon gas tank dedicated for the N20, keep 100+ Octane in it.  I did not do this, I used the existing fuel system and it worked great but I have heard great things about this setup.

If you do not want to go that crazy consider a Alcohol / Ethanol injection setup, that helps with detonation which means you can turn the boost up more and make more safe power.

Man, you are really making me miss my old FC.  I wonder if the guy that bought it either blew it up or killed himself.

For you guys that do not know, my 1987 RX7 had the same engine as Dan swapped in except it had a $10K rebuild done, all the best of everything added to it. It was built for huge boost like 24 PSI but I only ran 1 bar in it but would push to 18 PSI when I wanted which = 480 RWHP in a 2600 lb car.

I once raced a Porsche Carrera GT in low boost from 60 MPH up to 175 MPH and the Porsche was slower than my car. At track days I would push Ferrari F360 Stradale's around road courses and freak them out. This car was a monster, and I regret selling it, until I hear others complain about problems.  ;D

[94touring]

I'll never do nos but water injection yes.  In fact I've installed it before and the results are really good.  Doesn't effect power but definitely a reliability mod in case I decided to tear up the Arkansas roads one weekend.

[Jims5543]

I had the N2O setup on my FC back when I was into drag racing. Once I caught the Autocross and track day bug I yanked it off, the bottle was not allowed in the car for those events and the moment a tech inspector saw the actuators under the hood he would freak out and run to the back of the car to make sure the bottle was not there.

Plus I noticed a bit of an attitude from some tech inspectors. I did not need that BS so I pulled the kit off and sold it to a guy with a Caddy CTS-V.

[Jims5543]

Remember too, the H2O/Alcohol setup is a power adder, it makes the charge very dense and cold it also keeps things clean, you can run a few more lbs of boost using it and that alone is worth some decent power.

I never used one, I read a lot on it and it was not something I wanted on my street car that gets track driven. I was happy running lower boost and slightly lower timing and less HP. I just wanted simplicity.

You have the OMP on that thing still or are you premixing?

[94touring]

The kit I installed was purely for water.  We even dynoed it, but since we didn't change anything else the results with it on vs off were identical, except temps were way lower with the water.  After reading up on methanol am seeing you are suppose to run a 50/50 mix and it's the equivalent of running 116 octane.  Now I'm thinking about doing that and bumping the boost up a couple psi.  Kits are reasonably priced at around $400 for the higher end setups.

Omp is there, but I premix.  The previous owner did as well. 

[94touring]

Jim, I've been searching high and low for dyno graphs on anything comparable to what I'll have.  Best I could find was a pt6265, which is the old technology later replaced by the 6266 that's said to be much more efficient.  I also assume the blades are 65mm vs 66mm.  Anyways he made 470rwhp at 19psi on water/meth on 91 pump.  Not certain about the wastegate plumbing either.  Then there's the 550rwhp+ at 25-30psi crowd which isn't going to be me.  I'll go 3 rotor to get those numbers more reliable.

[Jims5543]

Yup 450-475 RWHP is all you are gonna squeeze out of a 13B-REW safely and reliably. Once you start going over 20 PSI the engine needs to be built up, most importantly doweled.

I think the H2o injection is a very solid idea and great insurance.

Excited to see what you come up with.

[roadhouse]

Go fast parts are always fun and exciting!

[MtyMous]

Dude, there's a guy with a MEAN sounding black RX7 here in the Dayton OH area. He is always ripping it along the backroads by my house. Love the sound of it. I can only imagine how much fun they are to blast around in.

[94touring]

Funny to think my 1275 is the same displacement!

[MtyMous]

Well F1 cars run 1600cc's. Your mini is basically almost an F1 car. My pickup has 5654cc's...sooo... basically I drive a spaceship to work every day.

[Jims5543]

Funny to think my 1275 is the same displacement!

I LOVED pointing out to Harley guys my RX7 had a 80 cubic inch engine in it make 550 HP. I melted their minds.... almost as much as the Ferrari driver on a road course seeing me eat up his mirrors.

[94touring]

My research on water/meth injection continues.  Rx7club has a whole section dedicated to it, who knew!  So sounds like 20psi on straight water is safe and as crazy as it sounds 30psi on water/meth at a 50% ratio.  Now I'm considering 18, maybe even 20psi on water/meth.  The other consideration is where to inject it.  Pre or post turbo.  I found a graph of a guy running 24psi that has a same day comparison.  The power curves are slightly different between the two.  Minidave which one looks better to you, since you're the power curve connoisseur!  Red is pre turbo and blue is post.

Link cause I can't save to my phone for whatever reason:  http://farm8.staticflickr.com/7008/6850333663_8c1e98f17e_b.jpg

[MiniDave]

Well, at first glance pre-turbo makes more power - probably because the action of the turbine blades mixes the liquid well with the air charge.....however - you are running water thru your turbo. OTOH, you'd only use this on hard runs, not constantly, so I don't think that would be a problem.

Also, you can see the power comes on sooner with the post turbo spray, so I guess it depends on where/how you're going to use it. Will it be an on demand style, keyed to boost or mechanically to the throttle or what?

[94touring]

I'd have it kick in at 10psi likely, and only that early so it's at full spray by time I'm over 15psi.  Day to day driving I'm rarely over 10psi.  I just couldn't decide if the midrange gain outweighed the lengthy top end gain. 

[MiniDave]

Well, as you know I'm all about that torque, because you don't drive your car wide open all the time. rather you're mostly in the mid range in day to day driving.

Depends on what you want of course......

[94touring]

This is one of the kits I'm looking at.

http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=161756170712&category=42604&pm=1&ds=0&t=1472321265569

[MiniDave]

I know several guys who use these on MINIs, usually with water/meth.....

[94touring]

In the midst of reading today and pondering what my timing should be over my current 15psi discovered that the fuel maps on my ecu peg out at 19.7psi.  I do have a 3 bar map to exceed that, but have to change the ecu maps to get fuel.  Looking like my datalog kit I bought for tuning does allow some kind of editing to achieve this but haven't found a good tutorial yet.

[Jims5543]

I never ventured over 18 psi so I cannot help. Typically ypu pull a little timing out as the boost goes up to prevent detonation. Using ethenol water injection gives you some liberties there though so I would do some research on club. Look for Pluto on there that is Steve Kan from Texas and he knows his stuff. Avoid BDC at all costs he built Tony Farkas' car that I bought and it was a habbled mess, makes skips work look like and F1 team.