WHAT'S BEHIND THE "GO" PEDAL


The heart and soul of any car is its engine


MAZDA'S ROTARY ENGINE
My initial peek at a rotary engine was in my '88 convertible. Did I have questions? You betcha! So when I looked under the hood of my current car I was able to deduce the following: two rotors, six combustion chambers, 4 spark plugs, 3 ignition coils, and two turbos operating sequentially. Oh boy this is going to be harder than I thought! And how much vacuum line is used on this car anyway? However, I really like the idea of powerful things in small packages. Like 255 hp from 1.3 liters! Compare this to the fox bodied V8 powered Ford Mustang 5.0 which only made only 225hp from 5.0 liters. I make this comparison because this was the "competition" at the time. Current iterations of the RX-7 sold in Japan are rated at 280 Hp. Not bad for a motor that's about the size of a CRT computer monitor.

1.3 Liters
of
rotating madness!
 
To give you an idea of how technically complex this engine is GO HEREto view the vacuum hose and system operation diagrams. 
MY ENGINE MODS
I will interject here that ALL work has been done by myself. And as proof I submit THIS!

Street port (intake and exhaust) w/portmatched manifolds. (Port work and Install notes)
Engine rebuild w/upgraded internals to include Atkins solid corner seals, competition oil control rings, and Atkins oil therma pellet. Polished rotor housings and front cover. Ceramic painted irons.
Ported oil pump housing w/ oil modifications to Eccentric shaft. (Port work and Install notes)
Ported and polished throttle body and Double Throttle Control removed. (Port work and Install notes)
Custom baffled Pineapple (GZ) deep well aluminum oil pan with Moroso oil pan stud kit.
Zeeshan SS tubular oil filler neck
MazdaSpeed rotor shaped oil filler cap
Tweak-It Racing airpump idler pulley
Custom made low profile urethane motor mounts with steel mounting brackets (Fabrication notes here)
Ceramic Coated LIM
Dedicated 2 stroke oil feed system w/custom mounted 1.5 qrt oil reservoir (Install notes here)
Braided SS oil injector lines
Dual Denso "Supra" fuel pumps w/in-tank fuel baffle box cover. (Information on basic Denso high flow fuel pump install Here)
All braided SS fuel lines w/AN fittings tank to engine (Install notes here)
Aeromotive A1000-6 FPR on custom mount w/pressure guage
System1 11" Billet 30micron Fuel Filter on custom mount
Garrett GT35R Single Turbo with SS tubular manifold from A-Spec Tuning. Ceramic coated pipes. (Installation notes)
SS Turbo coolant and oil lines w/AN fittings. Safety wired upgraded mounting hardware (Details Here)
TiAl 46mm Wastegate
TiAl 50mm Blow off valve
Vacuum lines "weeded" but airpump and emissions components retained.
Wiring Harnesss "weeded" and all unused solenoids and connectors removed. (Install notes here)
Dedicated 12V fuel pump 8g wiring
Crooked Willow Racing large "race" Intercooler w/custom fabricated aluminum hard piping. (Installation notes)
A'PEXi Power FC with FC Commander.
GReddy Profec B Spec II boost controller.

GM 3 Bar MAP sensor (Install notes here - bottom of page)

TechEdge Wideband O2 (Lambda) Sensor and Display. (Installation notes.)
1300cc Secondary fuel injectors. (Installation notes.)
850cc primary fuel injectors in a custom machined primary rail (Installation notes)
Crooked Willow Racing Dual Oil Coolers (Install info here)
HKS Twin Power ignition amplifier
Relocated OE Ignition coils on custom fender bracket
Magnecor 8.5mm custom cut silicon ignition wires
NGK 10 heat range spark plugs
Shane Racing Main Underdrive Pulley. Horror stories with installation (Click here to see what can happen if it's not done properly. Be warned it ain't pretty) of the Unorthodox underdrive pulley convinced me that to avoid any possible headaches the simpler bolt-on pulley would be the way to go. There is, however, the very nice 4 piece set sold by Unorthodox for $399.00.
Aluminum underdrive water pump alternator pulley
Unorthodox billet aluminum power steering pump pulley (details here)

Pettit billet aluminum power steering pump idler pulley
Exedy Hyper Carbon - Carbon D series 7 - Twin Plate Clutch and Chrome-moly Flywheel. (Installation notes)
Polished transmission Bell Housing
Race built Tranmsission with RZ short ratio fifth gear (Installation notes)
SuperNow transmission cooling plate and deep oil pan modification (With NEO RHD75W90 gear oil) (Installation notes)
MazdaSpeed Power Plant Frame
Banzai Racing transmission brace with Hyper-Flex bushing (Installation notes)
Race built Differential with 4:30 Ring and Pinion gears (With NEO RHD75W90 gear oil) (Installation notes)
GReddy large capacity differential cover
PowerFlex differential bushings
Braided SS clutch line. (Installation notes)

Optima Battery - relocated to the passenger side rear storage bin
ATR 3" SS Midpipe with high-flow catalytic converter
PFS 3" SS Cat Back Exhaust
GReddy elbow (polished)
Relocated Air Intake Temperature Sensor (Installation notes)
Silicone Intercooler hose connectors w/upgraded Breeze T-Bar clamps
Mazda Competition Race Radiator with custom made air ducting
REMedyHigh Flow Water Pump
OBX Red Silicone radiator hoses (details here) **REMOVED**
MazdaSpeed Coolant/Air Separation Tank (custom mounted and polished)
Custom mounted Moroso 1.5qrt billet Oil Catch Can with -8AN Braided SS lines (Fabrication notes here).
Custom fabricated oil pan baffle plate. **REMOVED**
Custom Made "sprung polished alloy engine brace
Complete vacuum line replacement w/Red Silicon Hose (Glued and Wire tied) Click Here for more info & pics.
Lowered AC condenser
NEO Oil full synthetic oil in transmission and Differential (RHD 75W90)
Redline Water Wetter in coolant w/distilled water 60/40mix
Polished Manifold and Intake Piping.
Custom fabricated polished alloy wiring and sensor brackets (to replace OE steel brackets).
Chrome engine lift bracket, alternator bracket, idler pulley, CAS bracket
Oil cooler fender liner vents and relocated washer fluid reservior


In early days my car used to be like a rolling advertisement for PF Supercars (then actually called Peter Farrell Supercars) but the times have changed. The shortcomings of the PFS system became apparent the more time I spent on the track pushing the power limits of the car. This in the addition to the fact that PFS is turned his attention to the Lexus line of automobiles for a while made my decision to move away from the PFS products perhaps a wise choice. At the time (c.1996) I was looking formy first performance upgrades I decided that PFS made the best overall package for the level of performance I was seeking. Granted it wasn't the largest intercooler but its fit and finish was head and shoulders above the rest. It was a very nice package. Then came the M2 and CWR setups which were the next generation of performance packages that equaled if not exceeded the quality of the PFS components and offered a step up in the level of performance. Of particular note, of not only the PFS package, but the SR Motorsports and M2 packages as well, is that these "types" of cold air intake takes air from the nose of the car and not the engine bay. Most of the competitors open filter intake systems are simply open filters drawing warm/hot underhood air. Cooler intake air means better power and increased reliability. Fast forward to 2009 and the setup-du-jour is the "V-mount" configurations. Essentaill this splits air coming into the nose of the car between a very large intercooler and the radiator which is flipped and tilted in the opposite direction. Pretty cool but requires extensive rework, exposes the radiator to road debris and makes it very difficlut to keep a working AC system. In light of all this I'm still happy with my CWR setup and even though the intake draws air from with the engine bay the impact is minimal due to the more open engine bay and more efficient single turbo.


The Original Setup - 306RWHP @12psi


THE FIRST STEP: A'PEXi POWER FC

In the beginning I chose the PFS PMS due to its user programmability and because it covered all the adjustable parameters - fuel, boost, and timing in one package. The programmability proved it's worth as dyno tuning yielded an additional 10RWHP. The others, that are drop in replacement chips, although cheaper in the short term, require upgrading anytime a modification is made to the powertrain. Not something I would wish to do as my modification path has been gradual, requiring frequent adjustment to the computer. However as with all good things there are downsides. From what I understand the EFI PMS is a variant of an ECU developed in it's early days for the Ford Mustang 5.0. EFI and PFS adapted this piggyback ECU for use in the RX-7. I have tried both the purple box and the Pink generation box and found them to work as advertised (see dyno results below) with one exception, a problem with the Pink box *in my car* at 6k rpm. So I decided to switch to the standalone ECU replacement, vs the EFI piggyback, and try the Power FC. I have no regrets over the switch.



Me with Peter Farrell @ Summit Point in the early days - 1998

EARLY DYNO RESULTS:

So what did my original setup with the PFS IC and intake, PFS PMS ECU, and running the stock twin turbos on an unported motor get me you ask? Only one way to find out....some REAL dyno tuning time! The car did pretty well apart from the glitches with the PMS which were never resolved >:-( Dyno testing was done using a DynoJet 1 chassis dynomometer with tuning using a wide band lambda sensor. Ambient temperature was about 45-50 degrees F and humidity in the 50% range by my own estimate. My car was tuned fairly conservatively in the interest of longevity on the track. There was room to run it leaner and which would have yielded more power but a single tank of bad gas would mean disaster so I decided to keep it safe.
Results below are using the EFI PMS "Pink 9" Piggyback ECU. Power FC dyno tuning with the new CWR IC and CAI to come . [*bracketed results taken using a G-Tech on previous occasions: first set of results without DP, Crane or pulley and second set with DP and pulley, the Crane Hi6 removed]
276 RWHP *CORRECTED* (325 HP at the flywheel), with the PMS computer controlling boost at 10psi primary/11psi secondary (essentially stock levels). This is about 70Hp over stock if you consider 15% drivetrain loss. [265 RWHP/312FWHP, 279 RWHP/328 FWHP]
305.6 RWHP *CORRECTED* (360 HP at the flywheel) with boost set at 12psi primary/13psi secondary. Flywheel Hp is again considering 15% drivetrain loss. [280 RWHP/330 FWHP, 296 RWHP/349 FWHP]

Halleluya! At last the 300 HP threshold has been surpassed! I think that the car is capable of even more as the 305.6 RWHP number was attained after 9 back to back pulls and the whole car was pretty well heat soaked. Also at speed the ram air effect in the PFS intake should be good for another 10 or so RWHP.
Notably, the numbers I generated earlier(bracketed above) with the G-Tech Pro G-Tech Pro were pretty accurate and definitely good enough to give you an idea of where you stand.
However, even though these numbers are good I believe I am getting very close to the limits of what is attainable with the stock fuel system and with stock turbos and an unported motor. Injector duty cycles are hovering around 85%. About the limits of reliable power. I'm too chicken to run at 14psi for the above reason. But I estimate at 14 Psi this engine should be good for over 320RWHP on a stock motor and turbos if more fuel is added. Hmmmm let me add some items to my list of things to do :-)
FWIW, these numbers are fairly consistent with the PFS claims of 300Hp, 330HP, and 360Hp at the flywheel at 10psi, 12psi, and 14 psi respectively.

I should also like to mention that I have no internal engine modifications, like porting or such, and am running on the stock turbos operating sequentially as originally designed, and with all factory smog equipment in place and functional.


CURRENT DYNO RESULTS:

A lot of time and experience has occured since those early dyno days! Things have been added like a single turbo setup, a completely revamped fuel system, and a worked over engine. This makes for a completely different animal. My have the times have changed. So with this in mind "Princess" as the car is now called was taken to PFSupercars for some dyno time. In the Summer of 2008 on a 90degreeF day using a DynoJet Research Dynamometer Princess in all her glory at 15psi laid down about
422RWHP AND 333FT-LB OF TORQUE

(corrected) to the rear wheels with an AFR at about 11.5:1. Not too shabby. Consider 15% drivetrain losses and this puts Princess in the 485 flywheel hp range. Consider the company of 485hp cars - Ferrari, Porsche, Corvette.... It makes me smile. And at only 3000lbs (wet), this is puts my car at about 6.2lbs per hp. There are VERY few cars that can boast this fact. VERY FEW! Do some research and you will see what I mean. But I digress. PFS also ran Princess at 12 psi and yielded 376rwhp and 293 ft-lbs of torque and at 9.5 psi yielded 326hp and 258 ft-lbs of torque. And consider that the modificatiosn i have installed there is the capability to run even more boost, and quite safely. I wonder what 17psi will deliver? Maybe someday. But let's reflect; in original stock trim the FD puts out 255hp at the flywheel at 10 psi of boost. Here, at the same 10 psi of boost (actually a little less), with the same engine but with significant external ancilliary modifications and a few internal modifications, the car made almost 375hp at the flywheel (considering 15% drivetrain losses). That's 120hp more than stock and at the same boost levels! This, in and of itself, is a testament to what the little rotary-that-could is capable of. For details on how I got here take look beginning with this page.


Removal of the Crane "Fireball" Hi6 Ignition Amplifier w/coil
Since testing I have removed the Crane Ignition amplifier and coil in an effort to eliminate the 6000rpm hesitation I have been experiencing at the track and recently on the dyno. In the interest of simplicity and with words of wisdom from those more experienced than I who say the stock ignition system is perfectly adequate I decided to pull the Crane ignition mods. Additionally, at the same time I replaced the OE coil wiring harness (Go here for a picture) that not only is prone to degradation of the insulation due to engine heat, leading to high resistance and subsequent signal failure to the coil, but that it also eliminated the splice where the Crane ignition box was wired into the OE harness. I have run the car at the track and found that without the box there was no (subjective) degradation of power. 


TRIPLE-R MAIN PAGE
GENERAL OVERVIEW | THE HEART OF THE BEAST | STOPPING AND TURNING | THE COMFORT ZONE

7-UP CLUB MAIN
OUR "LOCAL7" COMMUNITY | THE WORLD OF THE RX-7

This page last updated November 30, 2013
rotorphiles have visited this page since October 18, 2001

If you would like to contact me and converse about my experiences with my 7: please feel free to send an e-mail to crispyrx7@yahoo.com

Disclaimer: All images contained on this page are the sole property of C. Regan or were collected from the public domain, unless otherwise indicated. If any image contained on this page is considered private property. Please contact Christopher Regan.Webcounter supplied courtesy of 
Information below this line has not been contributed by the owner of this site