Murdered_Rx8

Hey guys, I hope everyone's having a great day! I'm kinda new to the rx8 club but I love seeing the wholesomeness and helpfulness from you guys. So yall should know I'm not an rx8 noob (my mom had a Semi-Auto 08' when I was in high school) so I know about maintenance and all that good stuff, the rx8 is one of my dream sports cars so naturally, I just snagged myself one (2004), it runs pretty great, it IS my daily driver ( yes, I know &#128556 but currently it's all I have.. the guy I bought it from done a swap from the Semi-Auto 4 speed to the fully manual 6-Speed. Unfortunately he didn't change the instrument cluster and little odd and end things. So my question to you guys (bc the Auto redlines at 7500, but the manual redlines at 9k) can I ignore the automatics 7500 RPM beep and reach the full potential of 9k RPMs like the Trans will reach? Or is there a good chance that if I run past the 7500 rpms that I break something?? I've been a mechanic most of my life and I'd feel comfortable saying I'm pretty mechanically inclined but 1. Rotary and 2. They're expensive when broken😂 Any help would be greatly appreciated guys!!

Killawatts

Semi-Auto? There's no such thing as a semi auto. Are you referring to the paddle shifters? It's just an automatic either way.

The whole premise of the lower red line was because the automatic transmission could not handle 9k.

But there's more to the swap than just throwing in a new transmission. Also, if it was a 2004 auto it came with the 4 port. Did he put in the 6 port with the 6 speed trans? Do you have one or two oil coolers? I would take some extensive pics of under the hood and post them here.

It's hard to say here whether it's safe or not, because I don't know if this swap was done correctly or not. Here's an example of it being done correctly, and what all goes into it.

Murdered_Rx8

I know it has a new motor/transmission. Not sure if it's 6 port or 4 port tho. I'm unsure on the oil coolers, I will take a closer look when I get off work. New clutch/brake pedal assemblies. Unsure on the drives haft as well. I know he had it done in a shop, he didn't do it himself. I'm pretty sure it still has the original wiring harness also. Most everything seems to work just fine, even cruise control and all that. When I get home I'll take some pics and figure out how to post them here. Thanks in advance

MincVinyl

Not sure about the Auto rx8's but on my 3 manuals it seems to be the same story. The beep is from the instrument cluster reading a certain rpm (lets go with your beep at 7500) So when your tach reads 7500 it beeps, but the engine/ECU is likely only at 6500-7000rpm. This error is either likely from mazda to make the car feel like it climbs in rpm faster and to make people shift earlier for safety. Either that or I just have a few **** instrument clusters that are off. On the current car I am tuning I know that my 9krpm(ECU reading) my Instrument cluster reads to around 10k-10.5k. Now the 9krpm limit is set by the ECU, which I would hope your car has the proper ECU.

Whether or not components will break on a nearly 20 year old Frankenstein car hitting 9krpm, ehh who knows. It's an easy way to find the weakest link I suppose.

Murdered_Rx8

That is true. I decided to be brave and just run it to cutoff. Fuel cutoff around 7700 rpm on the cluster. Which I've personally never heard of a MT cutoff that low and surely he changed the ECU having changed from AT to MT.

MincVinyl

I'd suggest having a second means of measuring rpm and not going off the cluster. OBD or mazdaedit/versatune

Killawatts

7700 is exactly where it's supposed to cut off....for an automatic, there's nothing weird about those readings, the stock cluster has always read high in comparison to the true RPMs. But the truth is, if it's a 4 port, it's not going to be making much power above that RPM regardless. That's what those extra two ports are for; air flow at higher RPMs. So again I ask; is there a 4 port in there or is it a 6 port? Here's an image taken from this very forum that shows you how you can tell. Or just compare the intake manifold, the 4 port looks different; as pictured.




The likely conclusion is you have a 4 port engine mated to the manual 6 speed transmission, and that's about the only thing that's been changed. When you go into reverse, do your white back up lights come on? I don't think it's even possible to put a 6 port in there without changing a whole lot more, because the PCM is different. And then you'd have to change keys. As I previously linked, to do it correctly, is an involved task.

I would disagree with you as far as saying he definitely changed the PCM, if he did, it wouldn't be cutting fuel exactly where an automatic transmission is supposed to. I'd be willing to bet that he just put a 6 speed trans in the auto car. The fact he paid a shop to do this reinforces that belief, because paying a general shop to swap out harnesses in the engine bay and the dash and all that, would be extremely cost prohibitive.

Killawatts

It's cutting fuel exactly where it's supposed to for having an automatic ECU. The RPMs are giving no indication of being erroneous.

MincVinyl

Yes I reread the original post and I had misunderstood what he originally said. I thought he meant that the original owner had not only been swapping just the trans, but the rest of the car.