miata questions: budget boost build edition

NickD wrote:

icaneat50eggs wrote: Another question, on the 6 speed, if you swapped the rear end for one that's much higher, couldn't you space out the gearing? I've read about this somewhere but I can't find it now.

I've heard about this. You use the 3.63:1 ring & pinion. Basically 1-5 are a touch tighter than a 5/4.30 and then you have additional overdrive with 6th. Unfortunately the 3.63 Torsen is super rare, (MSM only, I believe) so there goes "budget"

It's worse than that, the 3.636:1 was never sold in a US Miata. IIRC, it may have been used on some ancient RWD 626s, but they're not exactly easy to find. It was sold in some Australian Miatas, or the R&P itself is available from Mazdaspeed (or at least, used to be, I've heard rumors they've discontinued it) for about $600.

I have a 6-speed + 3.636 in mine, and it's great.

codrus wrote:

NickD wrote:

icaneat50eggs wrote: Another question, on the 6 speed, if you swapped the rear end for one that's much higher, couldn't you space out the gearing? I've read about this somewhere but I can't find it now.

I've heard about this. You use the 3.63:1 ring & pinion. Basically 1-5 are a touch tighter than a 5/4.30 and then you have additional overdrive with 6th. Unfortunately the 3.63 Torsen is super rare, (MSM only, I believe) so there goes "budget"

It's worse than that, the 3.636:1 was never sold in a US Miata. IIRC, it may have been used on some ancient RWD 626s, but they're not exactly easy to find. It was sold in some Australian Miatas, or the R&P itself is available from Mazdaspeed (or at least, used to be, I've heard rumors they've discontinued it) for about $600. I have a 6-speed + 3.636 in mine, and it's great.

That's it, it was used in the Australian equivalent of the MSM, the Miata SE. Basically an MSM with less boost and no Mazdaspeed badging. But yeah, quite rare.

I've heard that the combo is pretty slick and looked into doing it on my 1.6L car but the rarity of the 3.63 killed that plan

In case you end up spending too much money on building the engine, you could go the inexpensive route for the turbo and associated equipment. The MX6/Probe IHIRHB6 turbo, intercooler, and injector was enough to get a 2.2 liter engine with a low compression ratio (7.9:1) into the 200-220hp range at 12-14psi. The turbo very similar if not identical to what they used on 323 Gt turbos and GTXs, so it would be small enough that the lag wouldn't be too bad.