Renesis questions

[Rotary Related]

Does anyone know if there is a company making a throttle body for the renesis that has a place for a throttle cable and regular TPS?

Also in your opinion who has the best porting templates for Renesis engines?


I ask because I recieved a Renesis for free (Needs rebuilding, no compression on front rotor, but still runs.....kinda lol!) that will be living in my FB chasis with the help of a standalone and hopefully a normal throttle body.

I've never ported a Renesis but I imagine it is pretty much the same as any other rotary engine.

[RETed]

I doubt it'd going to give you more power unless you use the stock ECU or standalone EMS and control that...what...3-stage intake system?

For the complication, you're better off going with an older 13B...


-Ted

[Rotary Related]

Originally Posted by RETed

I doubt it'd going to give you more power unless you use the stock ECU or standalone EMS and control that...what...3-stage intake system?

For the complication, you're better off going with an older 13B...


-Ted

I understand your concern. From what I can tell it's just a two stage VDI system like a S5 NA engine, with 6PI just like a S5 NA engine. Has six injectors instead of four. Other than that nothing to crazy.

My FB currently has been setup to recieve S5 engines. If the Renesis is ruined I will ciontinue with the S5 setup. Renesis would be run in a bit of a stripped down version. Turning on the VDI and 6PI is easy I'm not worried about the wiring either, also easy, well to me. I gotta crack the engine open and see what the deal is. It maybe scrap. Then it will be for sale as parts lol!

Ever see a throttle cable controlled throttle body though? That's the biggy. I don't want to use the stock Renesis ECU since I would have to use all the emission related devices as well. That's just a lot of extra stuff for nothing. I don't have to pass smog or anything where I live in TX.

[NoDOHC]

It is a cool idea... I think it would be simpler to use the stock ECU and harness and then use the stock throttle sensor and throttle body.

Other options would require custom fabrication.

You should research the Renesis intake system, there are two VDI valves and the 6-PI.

If it were me, I think I would leave the ports alone and clean up rough edges. I never saw any conclusive proof that porting a renesis helped the power significantly over what a stock-port with a better fuel tune can do.

[Rotary Related]

Two VDI valves? I guess your refering to the SSV (Secondary shutter valve) as being a VDI valve. The one that controls the lower outer intake tracts. It also appears to be the thing that goes "clack" when you turn off the ignition. Well it makes the same noise as that when you mess with it by hand so I'm just assuming that's what it is.

[Pete_89T2]

Originally Posted by NoDOHC

It is a cool idea... I think it would be simpler to use the stock ECU and harness and then use the stock throttle sensor and throttle body.

Does the RX8 Renesis use a cable-linked throttle, or is it a drive-by-wire throttle, as many newer cars are these days? I don't know the answer to that question, but if it's the latter, won't he also need to transplant at least parts of the gas pedal assembly & associated wiring from the donor RX8 to get this to work?

[Rotary Related]

Originally Posted by Pete_89T2

Does the RX8 Renesis use a cable-linked throttle, or is it a drive-by-wire throttle, as many newer cars are these days? I don't know the answer to that question, but if it's the latter, won't he also need to transplant at least parts of the gas pedal assembly & associated wiring from the donor RX8 to get this to work?

You are correct in assuming it's drive by wire. You would need the pedal or modify the factort pedal to use the sensor or something along those lines.

The following is not directed towards pete_89T2:

Using the factory ECU is not the best choice as you would need various components from the RX-8 to make it work correctly. I haven't checked but the RX8 probably has a fuel tank pressure sensor or at least a evap pressure sensor or possibly both. So you'd need an rx8 charcoal canister and to modify your fuel tank for a pressure sender. You'd have to use a catalytic converter and two oxygen sensors to satisfy the ECU as well. Next you'd need the rx8 airpump and have to use the rx8 secondary air injection stuff. Using a standalone would get rid of all this and much more. You might even be able to use only four injectors instead of six. Using different sized injectors of couse. The factory ECU im assuming talks to the ABS computer and all that to calculate the traction control. So there's a bunch more rx8 stuff you would need to satisfy that. You can see where this is going. Let's just say it would be ten times easier to use a standalone and leave it at that.

It's not your car, it's not your engine don't worry about it. Just answer the original posted questions or don't it's pretty simple. Does anyone make a throttle body with a cable like a older car for the Renesis engine? I'm guessing the answer is no.

Does anyone make porting templates for the Renesis? Someone I'm sure does. I doubt the Renesis is so perfect from the factory that porting one would do nothing. Maybe it is I don't know that's why I asked. maybe NoDOHC is right in that respect.

The Renesis has a VDI valve (vacuum controlled like a S5 NA engine), APV (6PI valve direct electronic control instead of the older style vacuum controlled diaphrams), and a SSV (Secondary shutter valve which is also vacuum controlled like the VDI valve) for the record. The VDI adds the "supercharging" effect like in the S5 engine so it's just like the S5 engine, nevermind how it looks it provides the same outcome. So it's the same. The APV or 6PI does the same thing as the S5 NA engine so there again it's the same. It just opens the aux. ports nothing different there. True it operate differently but it does the same thing. The SSV has the ability to close the outermost lower port completely. This is not found on the S5 NA engine. So there's one difference. Who's to say it just couldn't stay open all the time? or closed all the time? or how hard is it to open and close? some wiring and a couple key strokes on a programable ECU software? wow that's hard how will anyone ever figure that out? It's two whole wires! I'll surely be defeated by two wires after all the work it would take to put that engine in the vehicle.

Anyways let's continue on topic and ignore the remarks of people who are not interested in finding the solution. I think I'm going to open the throttle body to investigate whether it can be modified to recieve a throttle cable which would make the swap much easier. If I do decide to do so I will post pictures of the inside of the throttle body for people to use as future reference, so they won't have to open one themselves.

[djmtsu]

The problem with using the Renesis in its 'factory' configuration is all the electric solenoids, intake staging, and the before mentioned drive-by-wire throttle body. I have seen a Renesis in a first gen, but it was an entire conversion, interior, dash, nearly everything.

This is the hardest/easiest way to do it.

Here is a couple pics for your pleasure.





I can't find the interior pics anymore, but it basically had the RX-8 cluster and center stack in it. Since the RX-8 is CAN-BUS, it needs all that.

One other issue with the FB swap was that the steering fault light was always on (since the car had a manual set-up, and the DSC doesn't work since the car had no wheel sensors or the yaw sensor.

[Rotary Related]

Originally Posted by djmtsu

The problem with using the Renesis in its 'factory' configuration is all the electric solenoids, intake staging, and the before mentioned drive-by-wire throttle body. I have seen a Renesis in a first gen, but it was an entire conversion, interior, dash, nearly everything.

This is the hardest/easiest way to do it.

Here is a couple pics for your pleasure.





I can't find the interior pics anymore, but it basically had the RX-8 cluster and center stack in it. Since the RX-8 is CAN-BUS, it needs all that.

One other issue with the FB swap was that the steering fault light was always on (since the car had a manual set-up, and the DSC doesn't work since the car had no wheel sensors or the yaw sensor.

Thank you for the post. Good stuff. These issues are why I'm not going to use the factory ECU. I'lll just use a standalone with the bare minimum sensors and devices to make my life much simpler.

[Dannobre]

The only comercially available porting templates are from Racing Beat...they are conservative ports...but there isn't a ton of room for much more there

There are 3 intake valves...the SSV and VDI are easy to actuate.....they have electrical solenoids for triggers and use vacuum actuators to open and close

The APV is a bit more difficult..but I believe a lot of newer ECU's like Haltech etc can actuate them. They use a reversing +5V signal to open and close the motorized valve

[Rotary Related]

Thanks for the info on the templates. If I go that way I will check them out.

Now the throttle body.......something has to be done there for sure. Anybody ever opened one before?

[NoDOHC]

I admire your ambition and the research that you are putting into this. I am very confident that it is possible to control the Renesis with a standalone. Drive by wire throttles are not that bad to modify (you can typically take the drive chain or gears off and install a cable connector). A have not done it personally, but I have several friends who have.

Just throwing a thought out there - I know that you can buy flash kits for GM and Ford ECUs that will remove all the OBDII stuff (2 oxygen sensors, purge valves, instrument cluster communications, air bag communications, Stability control, traction control, etc. If such a product was available for the RX8, that would be much simpler.

Please don't discard the idea, because such a product may be out there.

For future reference, on the S5 engine the VDI and 6PI is activated by pressure from the air pump.

Good luck with the project.

[Rotary Related]

Originally Posted by NoDOHC

I admire your ambition and the research that you are putting into this. I am very confident that it is possible to control the Renesis with a standalone. Drive by wire throttles are not that bad to modify (you can typically take the drive chain or gears off and install a cable connector). A have not done it personally, but I have several friends who have.

Just throwing a thought out there - I know that you can buy flash kits for GM and Ford ECUs that will remove all the OBDII stuff (2 oxygen sensors, purge valves, instrument cluster communications, air bag communications, Stability control, traction control, etc. If such a product was available for the RX8, that would be much simpler.

Please don't discard the idea, because such a product may be out there.

For future reference, on the S5 engine the VDI and 6PI is activated by pressure from the air pump.

Good luck with the project.

I had considered the whole flash thing. I'm personally gonna pass on that, but that could work fine I'm sure. I've got three local buddies with RX-8s as well and that had been mentioned as one possibility. This is a great possibility for someone who doesn't want to mess with tuning a ECU or doesn't have the ability.

I know the S5 is with pressure vs. vacuum but it makes no difference in the difficulty, vacuum actually makes it even easier really. I have a S5 NA FC. I think I'm going to got crack this throttle body open and see what's possible. After reviewing the wiring diagram for the TB I think the best thing to do is actual it by cable. It's simple and has worked for 100 years or so. Not that I'm against drive by wire as it can achieve some things cable throttle bodies can't do, but those are all things I don't need for a FB project car. Like traction control.

I'll try to keep the info in this thread so it can be looked up in the future. I don't know if it will ever help anyone, but at least you will get to see the inside of a RX8 throttle body if nothing else lol!

[NoDOHC]

One more thing: I doubt that the RX8 has a BAC valve or an Idle air control servo. It likely uses the throttle plate to regulate idle. You will probably have to use an RX7 BAC valve unless you want to run without Idle air control (I control the idle with ignition timing and it works very well).

[Rotary Related]

Here's the inside of a RX-8 throttle body for future reference









And the inside of the black cover: