So, it's getting about time for my DD to get a few upgrades now that I've got her mechanically sound and brought back from a 5 year sleep.

First off, I'm starting on a bone stock S4, except for MOP being disconnected and running 2 stroke, a corksport rad panel, and removed sub-zero.

I'm looking to do an RB RoadRace exhaust, 9.7 rotors, a large street port, and probably a pfc. I don't know what to really do about intake.

My questions are what kind of whp numbers am I looking at and what kinda mileage would I get? I know the large sp drops off a bit but would I be able to tune out fuel enough to maybe get what I'm getting right now?

 

Maybe 145 whp and 17 mpg's.

 

about 150 and maybe 20mpg with a decent tune and free flowing exhaust, maybe 170 if you run the S5 intake versus the S4 with the 9.7 rotors.

 

https://www.rx7club.com/time-slips-dyno-128/s4na-dyno-157rwhp-970927/

My average fuel economy is currently 21.26, best is currently 24.23, worst is 18.91MPG. It's gotten a bit worse lately since I've had to do a lot more city/warmup driving. Previous to my latest fill up I never went below 19.

Also, why're you removing the OMP if you're DDing it?

If you're street porting and tuning you should be able to hit 180HP.. I managed 157RWHP with stock [intake] ports and no tune [the little bit of tuning the dyno guy did was only safety tuning.. The first two runs when he let off early it was tracking to hit 160HP.. >_<]

If you're only looking for 160HP~ you could just leave the intake ports stock.

 

safety? sometimes i think people overreact to the reliability of the rotary engine and tuning. you really have to be trying to blow up a naturally aspirated rotary engine, otherwise it had issues to begin with. i had an S5 with a phantom injector issue, while playing with timing i had it advanced about 25 degrees or so.. while tuning i had it leaned out to 13.6AFR.. the only thing that finally killed it was a tension bolt that backed out and it overheated, the seals were also chattering from the extended 9k RPMs on the track even while overheating.

 

@Derekcat, I'm not sure my MOP is actually working. I've put about 2.2k on it since I've gotten it running again and my level hasn't dropped even a mm. So, I'm just playing it safe. Also, the Mobil 1 is still the same golden color as the day I put it in.

@Karack & jerd, I'm not going to be able to safely lean it out enough to get the 22ish I'm getting right now? If not that's cool, just seeing what is possible after reading how stupidly rich a stock N/A runs.

@Karack, are there any drive-ability issues with an s5 intake? I don't remember reading anything like that in all the tuts I've seen, but I could've missed it. Also, what's the diff in mpg if you have any experience? Does it make a diff between the RB streetable and their true duals in power and mileage as well?

 

can't really say for sure, but if you're going to use the S5 rotors then you should use the S5 intake even if you have to wire open the VDI. the VDI is about the only thing you won't be able to control with the S4 ECU but won't be a huge difference unless you wired it closed. you could get an RPM activated switch and wire up the VDI with that.

mileage should be similar to what you have now. opening up the airflow path both into and out of the engine actually almost always results in more mileage, if tuned properly.

 

Well, I'm looking into a PFC, would that control the VDI or is it vac operated? I don't know much about the S5 intake differences.

 

it's vacuum operated, i don't believe you can control it with the powerFC unless you rigged it up with the one of the solenoids off the twins system and set the twins staging point higher. which i suppose that WOULD work actually, but i have never attempted it.

 

So, basically I could just do the electric 6pi conversion from RotaryResurrection.com for the vdi instead? Assuming it runs off the same amount of pressure or would that not work?

 

i don't believe it is pressure but vacuum, much simpler to work with. the twins have correction factors with the datalogit and FCedit software so a solenoid could be ran off one of those circuits without need for an auxiliary controller.

 

......After twins I was lost. First off, twins? Actually I think that's all that lost me, just not knowing what you are referring to.

 

the PFC is actually made solely for the FD and it's twin turbo system. so there is some unused wiring when adapted to an FC.

 

Oh, any better/other recommendations for what I'm planning? Also, after some thinking, could I just tee into a vac line and run an rpm switch and solenoid for the vdi?

 

Damn, missed the edit time frame. After rereading about the S5 intake mod, I really don't trust myself to take on such an ambitious project.

About the S5 rotors, would I have to send them off with my e-shaft and have them balanced or would I be able to just install them and go? With the correct counterweights of course.

Also, Karack, I just noticed your sig and will be pm'ing you about porting here in a bit.

 

Yea.. I didn't really think the safety tuning was necessary, but I figured it couldn't hurt..
My Hi-Lo change over is at 70% via the pressure sensor tap [instead of TPS] and my Lo is set to -7% until around 4K [This is on my SAFC2]

For 5th/6th and VDI it's ideal to use a couple solenoids and RPM switches.
I'm pretty sure it's also pressure activated [hence the need to retain the airpump for S5 NA cars]

OMP.. Always a bit odd - I never really notice a drop either until I'm near my oil change time..

Yep, S5 rotors can be used with your S4 eshaft [all 13Bs use the same one]. Just get the S5 front counter weight and flywheel.

 

well if it's pressure operated the only difference is tapping into the pressurized ports to the 5/6th port actuation system for the S5. i suppose it would be simpler to just use the S4 manifold first and if the power is still lacking then try experimenting with the S5 intake system.

i wouldn't bother balancing the rotating assembly, that is only necessary if you plan on running the engine past the standard redline of 9k. just use the correct front and rear balancers for the rotors being used.

 

Okay, now I just need to figure out an EMS that will work for what I need/want to do. I want to be able to have plenty of flexibility for future upgrades and not have to buy a new one.