crouzer

What kind of horsepower and torque might we see in Stage 1, 2, 3, and 4 aftermarket performance modifcations for the RX-8 Renesis?

I would assume:

Stage 1 and 2 using a stock naturally aspirated Renesis.
Stage 3 and 4 using a forced air induction converted Renesis.

If you have insight or experience maybe you could provide a guestimate for us? Thanks!

Efini 8

what do u mean stage 1, 2, 3, 4... I do not get what you are asking

j9fd3s

well your cat back is gonna maybe add like 3-4hp (stock is pretty big), intake is gonna loose 3-4 hp the stock intake is huge. headers wont really work on the renny because of the motor mount and the center exhaust ports are shared so you cant get a scavenging effect. taking the cat out will help but not as much as the earlier rotaries because thiers less over lap. porting should make a huge difference, but are you going to rip apart a car under warranty?

mike

crouzer

All stages usually include an actual chip upgrade, an ECU swap, or reprogrammed ECU. All of these are commonly refered to as a "chip" upgrade these days.

Stage 1: "chip" upgrade with modest performance gains in naturally aspirated engines but can have great gains in turbos by increasing the boost in a stock car.

Stage 2: intake and exhaust modifications.

Stage 3: intake, exhaust, and upgraded turbos.

Stage 4: intake, exhaust, turbos, intercoolers, etc, etc. Usually a monster of an engine setup with lots of power.

crouzer

Yeah definitely not, it would just be something to look forward to in the distant future.

evel333

I've always thought using the term "stage" is just an arbitrary designation by tuners to denote their different levels of modification and have nothing to do with what's actually included.

wakeech

...it is.

crouzer

Yup. Most have mods and stages like I have listed above to cover the range of price and modifications available depending on the model.

Farsyde

i think we've been speculating performance gains in like 7 other threads. For the love of god no more honda math!!! bump...

Efini 8

wouldnt the ECU most likely be reprogrammed or replaced after one implements a forced induction system or anything that affects the air or fuel into the engine?

crouzer

I knew I should have put this in each entry. But I thought this at the very beginning would be enough.

daedelgt

As a benchmark, the RX7 gains about 15 HP by replacing the pulleys with lighter ones, and about 25 HP by replacing the precat with a downpipe.

I have also heard that a stock car with an extremely well tuned ECU can deliver an increase of 30 HP.

:D

The Beav

one thing is that when "we" would get an ecu reprogramed our primary concern would be performance, where-as mazda's was fuel economy, emissions, and performance, i know the wrx gets alot of power out a ecu, because it's engine backs off the boost at rpm near the redline, maybe the eight leans down the fuel mixture i did notice in the torque curve that it's hp goes down for just a little bit immediately before the redline

B-Nez

I was thinking about porting options the other day...I think once my warranty runs out I'm gonna go nuts. So, maybe someone can give me a clue here. Given the pros and cons of the different porting types used in rotaries, would there be any benefit (and would it even work) to the following scenario:

1. Primary Ports: stock
2. Secondary Ports: street port
3. Auxiliary Ports: bridge port
Obviously the stationary gears would need to be hardened (and a couple other things I forget) and the redline bumped up.

I figure keeping primaries stock would alleviate the idle, streetability, longevity, and low-end torque issues you get with normal bridgeports. At that mid rpm-range the street ports open up real nice, and for the WOT runs a nice bridgeport up to 10 or 11K would be gravy.

Of course, this is all speculatory, as I have no engineering background or any kind of experience with porting, and the fact that porting also retunes the timimg (so they may not work together like that). Also, I know that the 13B 6PI was not very port-able due to the 6PI sleeves. Does the Renesis use sleeves, too? I haven't really seen anything on that.

Edit: Okay, just flipped through the hardcover...looks like the auxiliary ports ARE actuated by a cylindrical valve similar to the 13B. This valve is inside the side housings, and is flush with the backside of the port openings. The secondary ports are actuated in the manifold housing. Lemme scour and see if anyone has come up with a solution to porting the auxiliaries. By the way, referenceed page 114, photo 3; and page 75, drawing 1.

B-Nez

Okay, scratch all that junk. I just read up on porting (like I should have done in the first place) from this site that wakeech posted in another thread. I also examined our stock ports on page 60 of the hardcover. I can see how there's no place for overlap of primary intake with the exhausts. And yeah, all of their examples are on 4-port housings. I'm starting to put it all together in my head...I'll post my comments later.

wakeech

...*cough*... i think you mean tertiary ports.

B-Nez

Oh no you don't mister! Won't be seeing your picture in the 2nd edition of the hardcover book - credited for REnaming the 3rd intake port! :p

wakeech

...the hell're you talkin' about man??? "auxillary" the dumbest name for it... i mean, if they called it the "power" port, then whatever... *sigh* i don't wanna get into it again, but sheesh, at least my name makes sense. :p

B-Nez

It may not make sense, but it's heritage, man. The third port has always been called 'auxiliary', and Mazda is still calling it that - at least they are in the hardcover book. I guess we'll see when we get our Factory Service Manuals :D

vipeRX7

as long as we're speculating ...
FD engine mods reached up to about 650 bhp while maintaining *decent* reliability. Granted, that was with 3 rotors, but consider this:
Base 13B: 160 bhp
Renesis: 247 bhp
Tuned 3-rotor turbocharged (20B) version of the 13B: 650 bhp
Assuming proportional power increase for a Renesis: Tuned 3-rotor Renesis: 1003 bhp!!!!!!!
Come on Peter Farell ...

--EDIT--

Note--I should have said "Tuned 3-rotor Turbocharged Renesis"
Sorry if that was not clear (I really, really, doubt anyone could get 1003 bhp from the renesis in n/a form)

rotarygod

The Renesis intake runners have been tuned for the exact port timing they have now. Any porting done to the engine will require a new intake manifold design for the runners that correspond the the enlarged ports. I know how to calculate intake runner length (even on a rotary!) so if anyone needs proof shoot me a pm for an explanation in numbers. Even the air filter housing is designed around the Helmholtz effect! Mazda did everything right on this engine! I suspect any gains that are to be had are not going to be all that spectacular. Don't expect gains like the 3rd gens had. You can't compare a turbo to an n/a when you talk about gains. Even the exhaust is going to be hard pressed to get serious gains out of. I would suspect a few hp at least though. The Renesis, unlike every previous rotary engine, had no port overlap. It has 64 degrees of dwell. A properly designed header system plays a big role during overlap due to scavenging. Scavenging not only helps clear the chamber out but also helps pull in air by creating a low pressure zone during port overlap. This low pressure zone helps pull in air. The Renesis can't benefit from this with no overlap. The siamesed center runner also messes up tuning. It may prove beneficial to seperate these runners as others have speculated since we can't get a true tuned length exhaust when 2 mix at the engine and 2 mix somewhere else with the center tube. Only time and experimantation will tell though. I truly hope the gains are there. It would be nice to get 300 hp out of that engine!

P00Man

does what you just said translate into "without FI, hp gains of any sort will be minimal at best on the RENESIS"?
________
LovelyWendie99

rotarygod

FI? Fuel Injection? I think that based on everything that Mazda designed into the new engine, they have pretty well utilized its performance potential. This doesn't mean that we can't get more from it. What it does mean is that horsepower gains are not going to be anywhere near as great percentage wise as they would be on the 13B type of engine. We aren't going to see any 30 hp increases from an exhaust nor are we going to see anything impressive from an air filter. Don't expect horsepower gains on this car to come cheaply or easily.

Farsyde

FI = Forced Induction aka super/turbo

rotarygod

Ah duh! Should have guessed that :D That's basically it. I do hope that I am wrong though. Mazda did a wonderful job designing this engine optimally with very few short cuts so gains short of a turbo, supercharger, or nitrous are going to be few. Again, I hope I'm wrong!