I know most ppl here are gonna hate this Idea but I don't need 400whp... after owning an 8 for 3 years, the light weight of an rx7 would make it quite fun with a lot less headaches....imo

 

I have no idea if anyone has yet, but weight wise there isnt a huge difference between the 7 and 8.. ~240 lbs

RX-7 Coupe RX-8 Manual
Curb Weight - Automatic (lb.) 2857 No data
Curb Weight - Manual (lb.) 2789 3029


Edit: forum didnt hold formatting, Oh well.

 

oh I thought without the turbo's and some weight reduction...2500lbs isnt out of the ?....:/

 

What is the Renesis? I researched it on the internet just now and found the hybrid hydrogen rx8. I filled out an inquiry form on Mazda Japan's site asking about it because I have a 91 with a 13b na that just took a **** on me. I'm building it race spec this year, but I want to do it with alternative fuel. Mazda Canada called me back telling me that they forwarded me to their engineers who are still "supposed" to call me back. Plus I'm going to structurally modify the car and have no problem dropping the car under 150lbs and having weight storage capability to fit into power/weight ratio classifications. So far it looks like I'm still building this alone, and I have researched and am pondering back and forth between the 20b twin turbo and the 26b 4rotor but haven't started quite yet...

 

renesis= rx-8 engine N/A engine.

 

y do people think of such things?

 

A friend of mine has wanted to do the same thing for a while now. It would make for a fun car but most importantly it would make a 3rd gen reliable which is something it is not. I say go for it. Remember that you'll lose more weight by not having the turbos and everything associated with them. The weight difference is 8% between the two stock cars which is noticable. Throw a real light flywheel on there and I bet it would be a fun ride. Do it! Forget what others think. Most people here still think the 13B is a better engine too but that's an entirely different topic that would take pages to answer.

 

This is certainly true in stock like form, but with a resonably sized turbo, a PFC, inteligent tuner, and the removal of all the crap that controlls the stock turbo's and emisions, you could easily have 300 WHP or more for allot less money, and be allmost as reliable, with much more torque and power throughout the rev range than the renisis option. It would be much lighter than a stock turbo setup aswell.

How reliable is a stock fd trans going to be spinning to 9K rpm?

The renisis engine controll system is far from uncomplicated, I imagine it would be a wiring and install nitmare getting it to run in an FD.

 

Standalone ecu. It's easy. He doesn't want that much power. He wants a fun simple reliable car and a Renesis in a 3rd gen would do it very well.

 

There is no reason a 13B-REW can't last over 80k miles. Unless you are using it as a grocery getter, this is 8-10+ years of driving pleasure between rebuilds. Reliabilty my ***. Quite a few RX-8s have had blown motors too.

I love swaps that result in making a lot less power in the supposed name of reliabilty. Right. I'd love to see the cost of doing this swap. I bet it would easily pay for AT LEAST one engine rebuild, which kind of makes the whole thing pointless, doesn't it?

 

we are talking about completly stock cars here with no silicone vacuum hoses or other "reliability mods" I have seen at least 2 FD's that went past 150K miles.

90% of what makes the FD un reliable is the complexity of the system, and the stock computer. Hell a vacuum leak can lead to catostrofic engine falure. There is no reason a modified FD which makes even 100 more HP than stock can't go well over 100K miles (or even 150K), by eliminating many faulty stock parts.

There are FC T2's with over 200K miles completly stock, and many with well over 150.

Won't make near the power of a stock renisis, and even if you get close at the peak the midrange will suffer allot.

 

I agree with rotarygod.

And martha_91, please don't take this the wrong way, but why should Mazda's engineers spend time talking to you if you don't even know what a Renesis is? I just thought the Renesis was common knowledge at this point.

 

That's complete and utter bullshit! Go learn how to tune. If he's going to use the Renesis intake manifold, all you have to do is tune it. It would actually be easier to get MORE power than stock with a standalone. I already did it on a friend's RX-8. It's not much more but more is still more and good tuning is good tuning.

 

What ecu can run the many stepper motors required for the renesis?

I know, haltech can't do it, without converting to a standard throttle body and dithing many of the electronicly controlled intake features the stock setup uses to have a decent torque band, which btw fails when compared to a bone stock fd.

You retuned a friends RX8 is that with a true standalone, which one?

How was the midrange compared to stock?

If your going to call BS prove it.

I will admit that haltech is the only ecu I can or have attempted to tune

 

Interceptor-X is a Microtech unit (more or less) that has been adapted to the RX-8. The RX-8 ecu still controls some vehicle functions but all ignition and fuel is controlled by the Int-X. That makes it a true standalone from a functionality standpoint.

It is very easy to control the VDI, SSV, and aux ports on a Renesis without any fancy computers. The SSV, and VDI are still controlled by vacuum pressure through solenoids. You just need to have an rpm switch that tells these solenoids when to open. That's it. The Int-X allows you to change this to whatever point you want to. If a Renesis were installed in another car, it would still work the same. A vacuum signal is applied with a solenoid in the way. It gets triggered by a signal to open. It can be a programmable output from an ecu or even from something as simple as an MSD rpm switch.

The aux ports are a little different in that they are no longer done by vacuum. That's OK. It's still nothing more than a simple electrical signal that you send at the rpm you want it to open at. That's it.

You could even take a Renesis, install it in a 3rd gen, use a 3rd gen's Power-FC for ecu control and wire it up to a Renesis. You'd need to use a simple cable actuated throttlebody and use a couple of simple vacuum solenoids to vacuum ports. If the Power-FC doesn't have the outputs to control these, use an rpm switch. Easy. Even though the Renesis has 6 injectors, you'd just rewire them so that injectors 4-6 all fire together. That's the way the Int-X does it. When I made a Megasquirt work on an RX-8, I did the same thing. It works fine. At this point it is a map based system rather than a maf based system but people are already running them and I already had a map based system running on a Renesis when I wired up the Megasquirt. I didn't keep it there though. It was only an experiment to see if it could be done. It wasn't something that was ever intended to be used. It works!

None of this is rocket science. It's very easy common sense. You use a Renesis and it's intake manifold and make the valves work properly, which I've already stated how to do, all you have left is to tune it. That's it. That's not hard.

 

Thanks for the info rg. I'm thinking of buying a blown 3rd gen pretty soon. THen I need to find a cheap renesis with a 6spd tranny. or should I just use the 5spd from the 7? Also, if I were to use the interceptor x, I would need the rx8 wiring harness and ecu..... right? plus I'd need another oil cooler as well since most rx7's only came with one...unless I find a blown r1.

Ok...how much can I strip a base rx7 to? without the turbos, a/c, ect.

 

Cheap Renesis? Is that a reality yet?

Last time I looked, which granted was right around the time the RX-8 came out, they were obnoxiously expensive.

 

You can buy a Renesis engine rebuilt by Rick Engman for $2000 through Mazmart. There is a core charge though. That's cheaper than new and you know if Rick built it, it's going to be good. He changes some clearances inside from factory as he doesn't like them the way they come. You can easily sell a 3rd gen engine and turbos and get much of that money back.

The most difficult aspect of a Renesis conversion into a 3rd gen would be the motor mounts. It's easy to make a Renesis work in a 1st or 2nd gen with little effort and no fabrication but it's not that simple in a 3rd gen. That's where you'll need to get creative. As for the rest of the install, to make it easy, use a 3rd gen front cover, crank trigger, brackets for a/c, p/s, etc if you plan to keep them. It takes a little modification to make all the original stuff on the front of the engine work good but it's not hard to do and makes life easier when trying to finish up the rest of the install.

 

Let's see it!

:-) neil