Pro's and cons for the RX7 and RX8
 

Hello everyone, im new to the rotary engine and RX-7 and RX-8's as well. Im a college student looking for a great reliable and fast car so i was thinking a rx7 or 8. The problem is i dont know anything about the rotary engine but what i do know is rotays are know for blowing their seals which can lead to a pricey repair. I picked up an issue of Turbo Magazine when i saw they had a 3rotor powered yellow RX7, which caught my eye because i knew rotarys have a peak power of something in the 250's. Well this dudes rotary pushed out something like 415.3 on the dyno run and thats what got me interested with rotarys. Ive seen the 3rotor 20b rx7 (efini?) race in the JGTC 500 class. I live in florida so i guess Pettit Racing would be the best dealer.

My main question is will it be worth it buying a RX7 and getting that 20b engine installed, or would be be better to get an rx8. Also can you upgrade the rx8 from 2 rotors to 3rotors? because ive never seen it done.

Whats the differences between the RENISIS wankel rotary and the 13b FD3S rotary and how come there's not many aftermarket parts for the rx8.

Has anyone ever acheived over 600BHP from a rx7 or rotary powered car?

These questions probably have come up a million times especially from newbies like me but please answer my questions if anyone can.

Thanks HR

http://www.autoweek.com/article.cms?articleId=102042
If money is no object, that car was for sale at one time. Also, installing a 3 rotor in a RX7 is quite an expensive operation. You'll see in the article that the 3 rotor engine they installed is @1200 HP.
Not uncommon, but an ample supply of money is key.

I'll anwser the questions about the 8.
You can't add a third rotor to the Renesis yet, because the ECU coding hasn't been cracked just yet. You could rig up a total stand alone Engine managment......but then the intake manifold plumbing would have to be made up for the 3 rotor. You could drop a 20b in there thought and save some time. AcostaRacing did this.

One of the big diffrences between the Renesis and 13B REW is how it's controlled by the ECU. The Renesis is macro-managend to help w/ emmisions and whatnot. This is limiting the availble upgrades in power right now.

Some of the 8 owners are running the Greddy E-manage and after they have tuned it that stock ECU will change its AFR based on the inputs from the O@ sensors. Great huh? It "learns" your driving style....

if I had the money it would be a 7 w/ a 20b....

What was that a 3 rotor...Well here you go. Hope you gots lots of money!
http://www.racingbeat.com/FRmazda1.htm

Scroll down to complete race engines.

the ecu isnt the main reason why there isnt a 3 rotor renesis, its because the mid center 20B renesis side plate doesnt even exist. It doesnt matter what ecu you have, you cant control and engine that doesnt exist

Ok I'll give you that. Of course a 20b Renesis plate dosen't exist, and it maybe never will. I could have one made, but for the time material invested, it wouldn't be worth it for me.

The stock ECU on the 8 ,to keep all of the stock options, hasn't yet given up too many secrets.
Unfortunally for the "instant gratification" crowd we just have to wait when it does get cracked...

a
 

hope it helps...
search is a good thing here, too...

rx-8 is a great car- it's fast, reliable, fun, different, and looks amazing. In terms of upgrades, the 8 is limited because it is a new car with a new engine. The Renesis rotary is vastly different than the retired 13B. The Renesis is improved is many ways, such as with a new complex ECU and new side exhaust ports also improve emissions and reliabitly. And, because the RX-8 is NA, it doesn't have the complex twin sequential turbos that plauged the RX-7 for reliabiltly. Tje new Renesis is truely a different aminal and it can run as long as a good piston engine, getting well over 100,000 miles before needing a rebuild. The Renesis also has reduced rotor weight, triple fuel injectors, triple intake ports per housing, and the twin side exhaust ports.
On the other hand, the 7 is a true enthusiast machine thanks to it's ridiculous lightweight, low-mounted twin turbo rotary, and a short-throw 5-speed. Reliabily is an issue, even from the factory as these cars are plauged with boost problems, crappy plastics, '93's usually have pealing paint, the stock rims can crack, the stock stereo malfunctions, suspension klunks, and much more. But if you treat the 7 right, with a good rotary-specializing mechanic, don't beat on her too much, then she will reward you. I remember someone else saying this and it encompasses the RX-7 totaly; "The 3rd gen Mazda RX-7 is the diva of sports cars." Believe it.
As far as a 20B conversion goes, get ready to spend AT LEAST 20K, and if you get a 20B conversion for that cheap then let us know. A 20B conversion is VERY extensive, including a new steering rack (which I hate because the 7 has perfect steering from the factory), cusotm motor mounts, a different hood, radiator, and much much more. It isn't some simple bolt-on thing. Not to mention a 20B engine itself is very expensive as well, running you few pretty pennies. Then, if you want those astronomical horsepower figures you were talking about, get ready for another 20K in modifications. I forget how much a stock 20B makes, is it 350bhp? I can't remember, but nontheless it will be very very pricey. And you won't get 600bhp out of a 2-rotor if you are running 93 octane pump gas (non race gas) and still want your car to be streetable. But, 600+ ponies is possible with a 20B (read post above). Beware, it will cost lots of $$$$$$$$$$$$$$$$
My suggestion- you're in college. Get the RX-8. Initial expense will be greater but she will be cheaper to maintain and cause less headaches. Just browse the 3rd gen forums here and see how many people are posting with constant problems with their FD.
I got my 7 when I was in my ladder part of college and I paid the price. I had to bum rides from friends and random strangers when my 7 was down and out, and when she did run it wasn't always great. I even blew my motor on the highway while going about 80mph, nearly causing a 20 car pile-up. Oh, insurance is more expensive on the 7 as well.
Damn, all this talk about how much the 7 sucks is almost making me want to get ride of my fd for the 3rd time. Well, almost ;)

Think this through and make an intelligent discision based on your needs. Considering that you don't know much about the rotaries by your own admission, then I would go for the 8 like I said. But it is for sure which ever car you choose, you will be happy.

Dave

RX-7 (1993-1995) is faster but the RX-8 is more reliable! so pick from those 2

RX-8 with a 20B 3-rotor, making 900HP.

http://www.mazdausa.com/MusaWeb/disp...ningPersonal18

It can be done.

I wonder how much money went into that.

You can make a 12a push over 600 hp. Not easy but it can be done...

i'm not totally convinced of the reliability of the 8 so far.

every motor i've taken apart so far has had abnormal bearing wear (9000 rpm @ 50 psi oil pressure?), and the side seals are just hammered. i've found sade-corner seal gaps of up to .021" and that was with just 30k miles!