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littlefeck

FrankenBastard RX8 Turbo Build Thread

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On 4/15/2019 at 6:08 AM, John Ortiz Luis said:

Any updates?

Hi John, not a huge amount to be honest. I got to finish up the porting and just have to clean the irons for painting. The rotating assembly is still over with Garagereg in the UK. Apparently the essentric shaft I sent him for balancing was bent! The car it came out of previously had the clutch escape through the bell housing so that's what most likely caused it. 

I've also change my mind on the stock FD corner seals and will now be using Atkins solid corners.

Also I'm trying to lock down the wiring for the new ECU. Getting it to work with the RX8 CAN bus is quite difficult!

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Thank you for documenting everything and just doing this hybrid engine. I’m Trying to do a NA build but thinking about closing the plate exhaust ports. So I can just use the peripheral exhaust manifold. My goal is smog legal California with just better exhaust flow and reliability by eliminating renesis exhaust ports. Renesis rotor housings chrome finish seems pretty weak with wear. New GSl SE housings are cheaper too. New smogs only looks at system readiness status so as long as no check engine light it will pass smog and just make the exhaust manifold appear stock to pass the visual inspection which I know they don’t really check anymore anyway.

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I picked up a standard 6 port engine of unkown condition and it appears to have compression.  My plan is to stick this in the car to wrap up all the wiring and test various ECU functions without fear of blowing an expensive engine.

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I went to drill out the front iron to install the turbo oil feed. As i was drilling i realised it was only a brass plug pressed in which easily fell out. Unfortunately i had planned to tap a 12mm thread. Now i have to order a larger tap!

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As I'm using FC housings there is holes in the housing that allow coolant into the intake manifold.  Since this is not required,  i had to install some 20mm freeze plugs. I added a small amount of dirko sealant and pressed them in.

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I need an adapter for an electric water pump that also has an alternator mount. Billet boss have one but its very expensive. 

I know of someone with access to a mill but wanted to test my idea first. I have a 3d printer to hand so printed up a quick mock up.

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This is bad, but in all seriousness I created an account simply to reply to this thread and get updates. I've owned both an RX-8 and an FC RX-7, and wondered why with all the new tech that most people were afraid of the hybrid Renesis/REW. I have yet to see a completed one, let alone a build thread, and yours seems the closest to a serious attempt. I've heard that a few people did it successfully, namely Mazdatrix and rumors of one in Puerto Rico, but never saw write-ups, build thread, or dyno sheets. What makes this such a difficult build and why are people so afraid of it? Seems to me it combines one of the best intake designs with the freer flowing exhaust needed for FI.

And, having worked in the 3D Printing field for a while, that mockup mount is super clean. Nice job!

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Hi @Jacob Kilian, thank you for your reply. I too have always wondered why this is an engine combination that is rarely done. My best guess is that it either gives poorer than expected dyno results or is extremely unreliable! Time will tell.

As previously said, one of our members here ( @Bradyy works for Shaddow rotary in Ireland) has completed a normally aspirated hybrid engine. He too cut the rotors for deeper FD seals but had issues at first where he would spin rotor bearings. Since then he had the rotating assembly balanced and hasnt had an issue since. He went for a half bridge on the intake and blocked all side exhaust ports at the manifold. He had to do a small modification to the right hand side engine mount as the upper bolt interfered with the exhaust manifold stud. 

His car is still running the stock electrical system including ecu that we just remapped with mazdaedit. With the new exhaust ports we found his car to run very lean in the higher revs but it was easy enough to remedy.

We only road tuned his car so unfortunately dont have dyno figures (unless he dyno'd it since then) but the car is noticeably quicker.

 

The biggest challenge we face is the cars are right hand drive and the steering column makes routing the exhaust extremely difficult. 

 

I hope to push forward with this build as much as possible but with a full time job, a newborn added to the family and lack of proper garage, its going to take a while. I have most of the bits I need to complete so I just need time!

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On 6/11/2019 at 12:16 AM, littlefeck said:

Hi @Jacob Kilian, thank you for your reply. I too have always wondered why this is an engine combination that is rarely done. My best guess is that it either gives poorer than expected dyno results or is extremely unreliable! Time will tell.

As previously said, one of our members here ( @Bradyy works for Shaddow rotary in Ireland) has completed a normally aspirated hybrid engine. He too cut the rotors for deeper FD seals but had issues at first where he would spin rotor bearings. Since then he had the rotating assembly balanced and hasnt had an issue since. He went for a half bridge on the intake and blocked all side exhaust ports at the manifold. He had to do a small modification to the right hand side engine mount as the upper bolt interfered with the exhaust manifold stud. 

His car is still running the stock electrical system including ecu that we just remapped with mazdaedit. With the new exhaust ports we found his car to run very lean in the higher revs but it was easy enough to remedy.

We only road tuned his car so unfortunately dont have dyno figures (unless he dyno'd it since then) but the car is noticeably quicker.

 

The biggest challenge we face is the cars are right hand drive and the steering column makes routing the exhaust extremely difficult. 

 

I hope to push forward with this build as much as possible but with a full time job, a newborn added to the family and lack of proper garage, its going to take a while. I have most of the bits I need to complete so I just need time!

Exactly! I would think that realistically it can't be any worse than the previous 13B engines, but with higher compression. I've heard rumors that the hybrid engines only got about 280 whp on the dyno, which accounted for the lack of "builds" simply due to the lower than expected power gains. "Why build a hybrid when you can slap a turbo on?"-sort of mindset. Which, admittedly is a relatively known constant for power adders.

But, seems to me, that other than exhaust manifold and motor mount fabrication, it seems to me that the hybrid engine offers a lot better geometry at a similar rebuild cost. Why rebuild without the REW housings when it provides a better geometry for future forced induction? Even if significant power gains (and 60-80 whp isn't insignificant) aren't had, the simple fact that the better design comes into play with forced induction makes sense to me. I'm about a year or two out from my build, but I will be following this very closely for replication/inspiration. 

I did try and find some info on @Braddy car, but wasn't able to find much. Any links you might be able to share?

I've heard good things about MazdaEdit, and was looking into Versatune not too long ago. Any advice on why you chose MazdaEdit over some of the other tuning choices available now? I'm impressed that the stock ECU handled such a drastic change! Do you think it will handle having both the side and PP exhausts instead of just blocking off the sides?

Glad to have LHD cars over here, which should make my conversion a little easier.

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Sorry for all the questions, but what made you choose the REW rotor housings (that have to be machined) over the 84-85 gsle housings with the gasket in the right place already? I’m starting the parts gathering phase soon, and I’ve had the opportunity to buy the 84-85 ones new, but want to see if there’s some reason I shouldn’t. 

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