Hey all

Thought it best to introduce myself seeing as i'm new n'all and see what you all think of my plans.

As the title would suggest, planning to build a Haynes Roadster using an RX8 as a donor.
So far it's all only in the planning stages, move house at the end of the month and at very long last i will have a garage. Would be a shame to to put it to good use!

The intention is to use the engine and gearbox, diff, hubs, breaks, column and just about anything else i can salvage.
As for the ECU, that can go in the bin as it's far to complex and will use a Megasquirt. Was thinking about scraping the intake and using ITBs but after further thought decided will be easier and more fun to use some of the stock intake and bolt on a supercharger. All things going to plan should be pushing 350bhp+

I'm quite lucky being a CNC machinist, i have the facilities to make custom parts with ease. And soon to be working next door to the companies composites facility there is a good chance carbon fibre will feature heavily (or is that lightly )

So come on, feel free to cast opinions etc. I figure there going to be a bit of hate on the wankel...

Jonny

Sounds excellent, I do love a good wankel!!
I used to have a rotten old RX7 TurboII that I ran in the PPC £999 challenge. Great car, especially the engine, just rotten as a pear
Kinda wished I'd kept it as a donor

Does the Megasquirt work ok with the wankel then? Do they still have twin spark plugs per rotor as the turbos used to, with delayed firing?

I did consider an RX7 as a donor for a twin turbo fun, but they rare as rocking horse s**t and would be a shame to dismantle one unnecessarily.

They indeed do still have twin plugs with a delay. But after talks with Megasqurt, thanks to one of the creators owning an RX7 this is something they can accommodate
The oil metering pump is going to be hassle as it's controlled by the ECU depending on engine load and the Megasquirt can't doing anything with it.
Pre-mix is an easy solution, but ideally i'd like to run both.

There's at least 1 car Stateside that has an RX-8 engine and box using IIRC the standard ECU and clocks. There is also a guy on MX5Nutz who has a Renesis in his mark 1 MX5. And a third on here has one in a Westie.

I looked at putting a Renesis in my build along with mark 1 MX5 running gear. The challenges I saw were...

• bigger bellhousing, with possible fun and games getting the starter motor to fit
  
• the exhaust manifold wants to be in the same place as the steering column
  
• you'll be more or less on your own designing the wishbones to suit the RX-8 uprights
  
• it might need a very quiet exhaust - rotaries tend to be louder than piston engines
  
• trying to retain the OMP could be very expensive to do - I think Adaptronic in Australia do an ECU that can handle it. That's the ECU the guy on Nutz used
  
• if you get an engine with issues (which is what I was looking at doing), the seals and gaskets etc would probably need to come from the States and I would be sitting down if you need to find out how much complete rebuild kits and rotor housings cost
  
• it's not THAT much lighter than a mark 1 MX5 engine and box
  
• consumables are not cheap; coil packs can fail, OEM replacements are about 250 quid, spark plugs can be over 100 quid.
  

Thanks, this that could come in quite handy to know!

I believe there is also a guy in the states who has one in a Roadster with the auto box (yeah i dunno why you'd do that either) which is quite a bit bigger than the manual. Had to do a few modifications but it fit.

I'm planning to use the 192 engine, the intake is much simpler without the SSV. Getting that to work isn't worth the head ache!
It's also a 5 speed which saves a bit of weight. In a car so light really don't think the close ratios of the 6 speed are worth bothering with.
As for the starter and manifold, yeah i'll have some 'fun' squeezing them in no doubt.

You can pick up an RX8 with under 50k for less than 2 grand, least then i know there is a good chance it's all in reasonable condition. Once it's up and running i'm going to rebuild the engine anyway, full kit from the states is about 1k without housings. They are silly money!

The OMP is going to be a pain. There are some groups that have worked on putting the engines into planes and developed a unit just for controlling the OMP but finding anything out about them is proving tricky.
It cant be that hard, can it?
In a very basic form all you'd need is something that can take a reading from the throttle position sensor and drive a stepper motor accordingly.....

quote:

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Originally posted by JonnyH
Thanks, this that could come in quite handy to know!

I believe there is also a guy in the states who has one in a Roadster with the auto box (yeah i dunno why you'd do that either) which is quite a bit bigger than the manual. Had to do a few modifications but it fit.

I'm planning to use the 192 engine, the intake is much simpler without the SSV. Getting that to work isn't worth the head ache!
It's also a 5 speed which saves a bit of weight. In a car so light really don't think the close ratios of the 6 speed are worth bothering with.
As for the starter and manifold, yeah i'll have some 'fun' squeezing them in no doubt.

You can pick up an RX8 with under 50k for less than 2 grand, least then i know there is a good chance it's all in reasonable condition. Once it's up and running i'm going to rebuild the engine anyway, full kit from the states is about 1k without housings. They are silly money!

The OMP is going to be a pain. There are some groups that have worked on putting the engines into planes and developed a unit just for controlling the OMP but finding anything out about them is proving tricky.
It cant be that hard, can it?
In a very basic form all you'd need is something that can take a reading from the throttle position sensor and drive a stepper motor accordingly.....

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Pre mix is a pretty good substitute for the OMP if you use a good quality oil.
But in an ideal world i'd like to use both, with the extra power from the supercharger want to give it the best i can.
Another possibility could be modifying the mechanical OMP from an RX7, but I've no idea if that's actually possible or practical.

I really cant be dealing with the stock ECU, from what I've seen on other standalone conversions getting it out out of limp when you unplug all the bits you don't want is a lot of hassle!

I started mine a bit ago but life just go in the way a bit, good luck with the build

http://www.haynes.co.uk/forums/showthread.php?t=8521

quote:

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Originally posted by Dualist
I started mine a bit ago but life just go in the way a bit, good luck with the build

http://www.haynes.co.uk/forums/showthread.php?t=8521

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Whereabouts in Kent are you?

If you need any help with the chassis etc your welcome to look at mine.

I've also got a friend who's nutty about RX8s and is currently trying to turbo it

quote:

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Originally posted by Ben_Copeland
Whereabouts in Kent are you?

If you need any help with the chassis etc your welcome to look at mine.

I've also got a friend who's nutty about RX8s and is currently trying to turbo it

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Where abouts are you moving to in Hampshire? You may be close to me.

quote:

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Originally posted by serieslandy
Where abouts are you moving to in Hampshire? You may be close to me.

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Not that far from me about 20mins.
If the weather was a bit nicer I would drive up to you once you've moved.

[Edited on 16/10/14 by serieslandy]

You'll have to forgive me in advance if I call on you for help from time to time

That's ok. Been there, done that. Although I did go the safe route with a sierra donor and the stock pinto.
When Saturn sports cars were about, Andy started to use an rx8 as a donor then changed direction with the mx5 instead.

Have you registered on The Haynes forum? It's been quiet lately but there is a wealth of knowledge specifically for the roadster.

I was tempted to go with an MX5 or maybe a bike engine. But both have been done a fair bit now and I'm a big fan of things that are more on the unusual side.
I thrive on a challenge, it's the engineer in me

I haven't looked at any other forums yet, I'm going to need to no doubt. Must get in the RX8 ones and problem them about the OMP.

Ok, so i might have just done something silly...

Threw a friend of a friend a mindt condition 13B REW engine came up for sale at a bargain price and I've committed to buying it!
So, my estimated 350bhp just jumped to a potential 500bhp


The thirst for power continues!

13B REW it`s not good idea
high power turbo rotary generate huge heat
in 7 style you don`t have enough space for coolers