kellybrf

iTrader: (2)

why cant we modify the rx7 turbo for the rx8? i dont know much about the rx7, but i believe its a 13b as well, right? if not, stop reading and point out my stupidity, but if so then woudlnt logistics be the only obstacle in mounting it on the rx8?

Aoshi Shinomori

Sure it's a 13B but the renesis is a totally new engine. The rx7 3rd gen motor was called 13BREW methinks, as well as having peripheral ports. The RX8 is a multi side port and is set up differently than the previous engine. I think the only things they have in common are the displacement and the fact that they are rotaries.

SimplexEffect

i too have no idea why someone hasnt done this yet...

im not very knowledgable on the 13b engines and stuff so i cant be very smart in the rx engine history

mysql101

Long story short - it doesn't take all that much effort to drop a turbo into an RX-8. It's a lot easier than the RX-7 because the engine bay is a lot larger.

The problem is cracking the ECU (computer that controls the car). This is what has slowed down every turbo kit from being released. If not for that, we'd have turbo kits almost the same time the car was released.

brillo

the ECU in our car is really complex, in fact all newer cars are getting this way as automakers strive for greater emissions control and economy, which calls for insanely detailed computer control. its going to be interesting to watch, because simple computer hack jobs aren't going to do it anymore.

I bet what will happen is when Mazda releases its own FI RX8, people will reverse engineer the ECU and let Mazda do the work.

kellybrf

iTrader: (2)

so what about the cz? i know its just a piggyback, but its done a decent job of gaining hp when tuned. is it just a rudimentary band-aid that cant be incorporated into a turbo?

mysql101

cz just tricks your ecu to thinking less air is flowing, so the car responds by lowering the fuel it's injecting. This leans out the AFR and gives you more power.

brillo

I think its possible it could work in an FI application for a low boost situation, but if your really looking for both reliability and scalability, then you'll need something more advanced.

I think CZ is looking at a turbo application himself with his unit.

mysql101

several companies are using emanage (which is what cz is) to manage their turbo kits.

the ecu on the rx-8 controls a lot of functions, and the code is encrypted. It will be interesting to see when a replacement ecu is made available.

shelleys_man_06

There is also another FI option: run a stand-alone. Unfortunately, you're going to have to compromise important functions the factory PCM has. However, you have near-complete control of your inputs and outputs of your engine, which is really what you're looking for in a heavy FI situation.

More than likely, most people will never be in a situation in which the ideal boost very high, say on the order of 1.75 bar.

I'm still waiting for a company who manufactures turbo kits to utilize the Ric Shaw computer. I've only seen TSI and E-manage units. Also, try to check out what RB is doing. I haven't been in the tech forums in a while so I don't know how far Mederer and the boys are along.

shelleys_man_06

I wouldn't call a piggyback controller a band-aid solution. I tend to think of piggyback controllers as equalizers; you can control the inputs and outputs of the system by tuning various parameters. You're working with a closed-loop system, which means your output is directly affected by the input. Adding some control to can reduce errors in the uncompensated system.

A question to engineers:

What kind of controllers do PCMs incorporate? Are they lead, lag, P, PI, and/or PID? Someone once told me such controllers are embedded within the circuitry. I'm not sure.

Aoshi Shinomori

I thought the Ric Shaw unit is the TSI unit no? Maybe I'm mixing something up. You'll probably just mathematize me into a trance and make me wrong somehow anyway :p

kellybrf

iTrader: (2)

i meant in the fact that it is not an ecu, just an add-on that does the job well untill replacment ecus are out.

shelleys_man_06

Like what kind of replacement ECU? Stand-alone?