I'd rather put a supercharger on a more basic 13B than mess with funky port valves, variable length intake runners, high redlines and high overlap ports. Mazda themselves did this on the Miller Cycle engine on the Millenia S . . look at my avatar to see what that engine uses upstream its intake ports . .

 

Personally I'd rather have your n/a 20B!

 

Go check out Yamaguchi's RX-8 book for a little info on that early side port engine. It had less intake timing than the Renesis which translates to a longer dwell period (zero overlap). The ports were much smaller. There were only 2 exhaust ports, 1 on either side, no middle. The intake runners were long and smaller, the compression was lower, and the redline was lower. It's funny how it still produced similar power to the Renesis.

 

I would say to go for a streetported 13B.The stock intake manifold can flow allot of air.
Well to be exact a series 4 turbo manifold flows around 600cfm (the one with the 3x45mm throttles)
With bolt-ons,and streetporting,a properly designed exhaust,and loads of tuning,you will make 200hp+

As for all the negative comments on the MSP engine,i think it is really inovative.It wasnt made for max hp,but for being emmisions legal,with good fuel consumption.It is afterall in a sport sedan,and not in a 2 door coupe.I mean come on,it might not make the claimed hp,but it has made amazing progress over the more conventional Rotary engines.The is alott of questions i have myself about it,but i certainly wont say its crap.

Karis

 

I think if Mazda wanted to go beyond 238 hp, they most certainly could. I forsee the RX-8's power increase as it gets older.

 

I heard that the RX8 had a recall from mazda becuase of the HP overstatement. They gave back anyone who wasnt happy with the performance of their rx8, their money back in full. Im looking for a reference to that right now...
So to the guy that said that the hp comes in later on during the engine break in, if this were tru, why would mazda issue a recall for hp

im not trying to start anything here btw

 

That was so last year. Mazda has since improved on their word by providing free PCM flashes. I've said my piece. Argue all you guys want.

 

Mazda originally overstated the Renesis produced 250HP, but has since then dropped it to 238HP. I think Mazda handled the situation well as anyone who still wanted to keep their RX8 get free oil changes throughout the cars warranty. If they weren't happy with the car any longer they were offered full refunds.

I don't know how Mazda could overstate the HP number, but I assume it probably was a miscalculation with the added emissions equipment.

 

Scoot! www.rx8club.com - all the info you could dream of on the horsepower debate & flashes & such.

-=Russ=-

 

hey remember, Judge Ito made 240rwhp with a "bone-stock" motor. Of course it really isn't "stock", but he has to say that, to protect himself against legal action from Mazda. Why Mazda could bring legal action against him for something he OWNS is beyond me...
And since he has already been busted by MNAO for racing his car, and had to pay out of pocket to fix things, why now would you claim "Mazda police" are watching? Who cares....they already got-cha!

I dunno, but I thought that might ignite a discussion over here?

FYI, I think ITO is extremely well versed in the world of triangles. I have great respect for him. I just think it's funny how he doesn't answer some pretty obvious and direct questions such as those above.

 

Interesting graph...
Since you do mention it's a Kouki NA engine, I wonder why the numbers are so low.
Stock rated @ 160bhp at the flywheel, if we knock off 15% for drivetrain loss, it should still produce about 135hp at the wheels.
You sure it's an 89?
A Zenki NA motor rated at 146bhp at the flywheel, knocking off 15% for drivetrain loss, should produce around 124hp at the wheels - more in line with the dyno run.

I find it interesting that you can actually see the 3 stage intake triggering in the dyno graph.

I think the RX-8 is just like the Honda VTEC motors - the engine has been developed enough to run very close to it's maximum potential.
Does anyone have dyno runs of a modded (i.e. intake, full exhaust) RX-8?
Doesn't the RX-8 run a MAP sensor based load ECU?


-Ted

 

Nope, I don't forsee any power increase in the rx-8 without forced induction. The 13B is at it's limits seems like since aftermarket tuners are having a hard time trying to come up with products that give it much more power increase. Read the RB webpage about this.

 

The question is not what the renesis has, but what the renesis engine could do.

 

^^^^^

 

239.7 rear wheel hp If you do a search maybe you could find a dyno sheet.. V-tect timing works great on 6 port engines.

 

Ted,

From the Rotary Performance website, it says it's a 91, although it might be a s4 engine in the 91. All the information is from the same page as the dyno sheet and explains what car they are comparing. Granted a modified S5 engine will net the same type rwhp as the renesis, it will be cheaper and easier to install than someone trying to be the first to install a renesis in the FC (like stated above).

Tim


from the rx7.com website:
RX-8 Power: how powerful is the Renesis really?

We have all heard the magic disappearing horsepower numbers from the marketing sources. The question we’d like to pose isn’t “where did the horsepower disappear to”? Rather, we’d like to ask, how much more power does the Renesis make compared to it’s predecessor?

Keeping in mind that Mazda did not increase the displacement of the Renesis, and they managed the amazing engineering feat of reducing emissions at idle to 10% of what the 13B-REW (the Renesis’ immediate predecessor) produces at idle, and 15% of what the 13B-REW produces at cruising speeds and loads.

The argument can be made that the Renesis produces higher peak power because of its ability to rev much higher than the old 13B. So to be fair, let’s compare the two powerplants at the point where the old 13B is producing it’s maximum hp. In this chart, that happens to be at 7000rpm. At this point, the old 13B is making 125hp while the Renesis is making 175hp. That is a 50hp difference which translates to 40% more power (40% of 125hp = 50hp). For the sake of full disclosure, the 2nd generation RX-7 tested here is a 1991 with a fresh motor (less than 1000 miles), and the RX-8 tested is a 2004 with about 800 miles.

 

Just to comment on the Renesis not being able to make more power. Blitz is working on a compressor for the Renesis. Just a little tid bit. Not to mention the turbo kit I saw in a mag from the Tokyo Auto Show for it.

Yeah like I said before, I was just curious about how it made more power.(As some have answered). Also like before, if I was to attempt an N/A build up. It'd be a 20B, but me behind that motor = hella tickets(So I think). The sound of it would just get me hyped up. Hell my stock 13B causes me to become happy when I start it up.

As far as taking parts from a Renesis. That seems like it'd be an interesting experience. The rotors would be first if I was to attempt it. Isn't there someone who has done this already? If so, how did that come out & what motor were they using(S4 or S5/Turbo or N/A)?

So far I am doing a full RB exhaust & HKS intake, HKS circle earth kit(Anybody tried this before?), Jacobs Ignition, Pulleys, Fuel system, Rebuilt & Stage:1 Street port by Rotary Resurrection(Look for me soon Mr. Landers w/ the motor from Orlando). Not sure what else will be needed aside from tuning to reach the goal power range. But hey, i'm in it for the long haul. Right now I need to get suspension inline. Something about 235/35/18s on the back seems to **** off my 7. That would be the focus for a good drift setup. Look for the thread that says "Say hello to my TEINs...among other things"

Thanks for the response though, you all are pretty informative. That would be why I prefer this forum over others. Aside from the heated debates.

 

RETed. You said the "all out horse power" was being choked off because of the conservative timing on the exhaust ports, if this is so can't you just port the exhaust south so that the exhaust opens sooner? and stays open longer. to me that seems like it would fix the major problem with the 13B-MSP.
Truly i dont know a damn thing about the MSP other than the fact it has a new exhaust design.

 

Really? 6 year bump?

 

Rise from your grave!

 

just for the record it spits out 40+ more than what was listed when hand built by the right person

 

WOW totally didnt read the date on this topic... well i would still like to know, lol. Sorry the page pulled up when i was looking for something else to i decided to comment. almost feel stupid now...

 

I got a 6 port Renesis long block (and really like building custom manifold intakes) sitting in my shop right now. Care to provide a link with any info?

 

5.5 actually.