MichaelBrown

Hello! I currently own a 2006 Mazda MX-5 (The New Body Style)

The new MX-5 shares alot of components and dimensions as the RX-8. Sway bars can be swapped from the cars for starters. Also we can swap our engines.

Now, The RX-8 weighs around 3,000 Pounds. While the MX-5 weights about 2,450.

So my question... MX-5 + Renesis Engine = how much weight?

And because of this weight loss, obviously Power/Weight Ratio goes up. But another thing i wanted to ask, How much MPG will it increase because of the motor moving ATLEAST 500 pounds less?

KRNrx8Driver

umm...dude rotary engines will get you less MPG -.-;; i dont think 500 lbs could compare to like the 22+ in city gas mileage of the miata engine but whatever good luck. =)

GULAMAN

an interesting question in academic terms; but realistically....if you somehow went to the lengths to convert an MX-5 to Renesis power (don't know if anyone has), who cares what the new MPG would be????

it'll be a little bit better than in RX8 guise, but not by much, imo. surely not as good mpg as the factory MX5 engine though. but it would be a fun car for sure, and that's what everyone would be concerned with.

flomulgator

Maybe maybe not. Remember he is dropping some weight from the engine swap (although I'm not sure about 500#) and it is a much lighter car to begin with so he would achieve far superior fuel economy to us.

That being said, remember you are adding 50 ponies to the stable, so I don't think an improvement in fuel economy should be a goal here. Being a hero for swapping a renesis into an mx-5 should be
Good luck with the electronics.

swoope

iTrader: (5)

i would ask this ? in the mazsport section..

beers

otakurx

It would be a wicked fun car. There might be a slight increase in MPG but performance increases would be quite nice, since you will be loosing some weight and gaining a lot of HP. The first gen RX-7s weigh in around 2200lbs and they didn't show a great increase in fuel economy when the renesis was dropped into one of them. Just my .02

rotary crazy

Paul from mazmart is doing this swap, maybe you should ask him?

StealthTL

iTrader: (1)

You wouldn't be the first to do the swap, or even the thousandth, so why not ask someone who has done it?

One of many......

....and why stop at two rotors?.....these guys put in three!

S

rotary crazy

yes many have done it, but no one that i know of has done it to a new mx-5 the 2005 model

j_tso

the latest MX-5 is a bit heavier than the first one, so power to weight ratio would be less compared to a first gen swap.

Mazmart

iTrader: (12)

This is true. I believe I'm the first in the US to do this swap into the new chassis.

Paul.

rotarygod

With a different rear end ratio such as a 4.10 and less weight, a Renesis could get over 20 mpg city. That wouldn't be hard at all. The RX-7's don't appear to get any better or worse mileage than a Renesis but you need to remember that the RX-8 weighs more and the engine is always spinning faster when driving. The Renesis is a more efficient engine than the 13B in terms of economy but you don't see this since it's been offset by gearing and added weight. If a swap to a Renesis is also to see a fuel increase over a Miata engine, forget it. That won't happen. You might be able to match it, maybe, but don't expect an increase.

Mazmart

iTrader: (12)

Michael,

When you're serious let me know. I can help make this a reality. S2000s beware.

Paul.

DMRH

Dude.

Back in late 04, there where whispers from Mazda people that the MX-5 was to get 13B-MSP power by 06/07.

It appears that is not going to eventuate. Suspected reasons may be the sales of the RX-8 over the long term are not as good as Mazda want aswell as on going warranty issues plus legal claims for the (sue everyone for anything) American market .

Word was, the NC MX-5 was engineered to fit a 13B-MSP so you should not find it too difficult to install one.

Go for it & go hard in it..........

REgards

rotarygod

It's not designed to fit a rotary. The rear of the engine will hit the firewall. Paul at Mazmart is working his way through this. A couple of the big dog Mazda guys even addressed this issue in conversation at Sevenstock. At least they've tried it though!

rotary crazy

DMRH, long time dude

my cosmo is doing great really enjoing it, I just purchase another one , some guy got it to get the engine out and then change its mind after the car was apart! I just could not let it fall into the wron hands

sorry for the hijack back on topic

now that I have some time with the rx-8 my opinion is that a car like the mx-5 would rock with a renesis, even and fc or fd with some weight reduction will make a very good and fun daily driver, I belive a 2700lbs car with a renesis can mach or out perforn a 350z and similar cars

MichaelBrown

Actually guys, this one has been done. i believe that there is an MX-5 in Germany that had alittle front-damage when it was in a crash. the dude thought "what the heck, lets save a couple thousand and throw a Renesis in it!"

It's possible. and really the Gas Milage is not that big of a deal to me. the Power/Weight Ratio is. and ofcourse 9,000 RPM is always nice.

I just wanted to know the opinion of the RX8 Community.

DMRH

G'day "Rotary crazy". Glad to read you are still enjoying 20B-REW power mate. Nothing like 380nm on tap at 1800rpm hey!!!

Fitting a 13B-MSP into an NC series MX-5 (once past any engineering issues) would be cheaper if you are down under. Engine for engine wise (not including everything else for a conversion) a 13B-MSP sells for around AU$2k where the MZR2lt is hard to find below AU$3k.

Could be the same in other countries....

SayNoToPistons

iTrader: (8)

Mind as well swap a LS1 in there. Someone even swapped a LS6 in a miata.

MichaelBrown

Madness! Simply Madness!!!

V8's are fun. and a Miata with a V8 is even funner. but it isn't my taste, i'd rather have a rotary.

The way i see it...

A light weight car, should have a light weight engine, with a nice amount of horsepower.

Miata + Rotary = Light Weight Fun

flomulgator

turbines are ligthweight and put out more power than an LS-anything. A Cal-Tech prof put an old 1000hp Sikorsky in his VW bug last year.

Asides from the dificulties of finding jet fuel at the local chevron (it might burn diesel if your lucky), I say stick with the renesis.

Also keep in mind that if you have to do standalone engine managment to get it to integrate with the MX-5 you will get more power out of your renesis than we do, cause our AFR is neutered. Seach Interceptor-X + NA to see what kinda power the REN should be making.

And don't forget to slap a Type-R sticker on there!

gh0st

rotaries are not light weight engines.

they are quite heavy for their size and displacement.

Red Devil

My opinion is, it's your car so if you want it - go for it. And please come back to show us the final result and let us know how it went. I'd love to see the results.

SayNoToPistons

iTrader: (8)

It would be a better choice to swap a LS1 in it if he's willing to use the money.

Velocity

i would love to see evidence for this claim. Im not saying it's not true, just curious.