Is there anything to stop you using a Series 2 block in a Series 1 RX8?
 

Hey everyone, I've been on here a while but never really posted - I'm from Dublin, Ireland & currently drive a Series 1 6-port 13B-MSP powered NC MX5 that we just got driveable this day last week! :D:

I've not accumulated enough posts to start a thread in the relevant section so if this question has been covered hopefully I'll be able to pull the "noob" card & won't get flamed..! :o:

I've read the following 2 threads:
https://www.rx8club.com/series-ii-te...n-done-222458/

https://www.rx8club.com/series-ii-te...s-i-ii-161665/

...but haven't been able to get the exact answer to what I'm looking for: I know there are a fair few differences between the two engines in terms of their ancillaries (intake manifold, ECU, etc) but other than the 3rd OMP line per housing, is there anything to stop one using a Series 2 block (not including ancillaries) in a Series 1 car? Does the different sump foul the S1 subframe or anything to that effect?

You can fit the block in the car, that's fine. What's not fine is running 2 OMPs and 4 injectors instead of the 1 OMP and 6 injectors that S1 wiring and electronics expect.

And if you change the ECU, all the other computers need to change, and if you change those, some of the parts they're attached to need to change and pretty soon you've bought yourself a new RX8 in parts :)

I really just mean I was hoping to use the bare block of a Series 2 (e.g. front cover, front/middle/rear plates & housings) in a Series 1 engine bay, so do the 2 OMPs of the Series 2 engine not share the same mounting points as the Series 1 OMP?

And when you say injectors I presume you mean fuel, so would that not depend on what inlet plenum/manifold you're intending on using? So would a Series 1 complete inlet fit to a Series 2 block?

The injectors on a RENESIS motor are in the rotor housings themselves. There are a lot of sensitive differences between the two motors that could tick off the electronics if they perceive something different is going on. Best to stick with the motor the car came with unless you want to keep on changing things over and over again until you basically have an S2 like Loki said.

Really no. I mean, there are 2 of them, lol.
And they can't be driven by the S1 ECU, they are full electronic, rather than mechanical.

Cool - thanks for the info folks!

As a slight variation, would it be possible to use the S1 rear plate, front plate & front cover on an S2 block?

You probably "could" but why bother, and you wont have the pump to run the s2 oilmetering inthe rotor housing ( 3 instead of 2 in the s1)
I assume you are using aftermarket ECU?

I want it for sustainability purposes such as:
1) Increased number of oil paths (e.g. e-shaft)
2) Higher oil pressure & more flow from the Series 2 oil pump/pressure regs
3) 3rd oil injector per rotor to give a more even oil film on the housings (I'm sure a solution can be "engineered" to pump oil through each of the 3rd injector pipes)

Nope - standard S1 ECU: hence I want to run as many S1 electrical/electronic interchangeable components with as many S2 physical components as possible.

Sounds like a big headache, just buy a s2 or mod the s1 oil system pressure and run premix

+1, you can achieve 2 out of the 3 with much less headache. You can also increase the oil injection rate with Mazdaedit or a Cobb AccessPort.

As per my first post, I've modified my MX5 to use the Series 1 Renesis so "just buying a Series 2 RX8" isn't the aim of the game here! :D:

I've increased the oil injection rate already - was looking to see what the best I could get from a rebuild was semi-regardless of effort.