Shooting for ~300 whp, MSM diff?
 

I'm finally getting around to building my car, and I'm planning on an Efr6258 and 250-300 whp for a DD/Trackday car. Currently on a 99 5 speed, so I know that will grenade first and am looking for a 6 before I drop in induction, but after that I'm looking at the diff.

Is it worth hunting down a MSM diff at ~$1200+ dollars for used parts just for the stronger axle/CV? I don't see many broken axles (except from Miata drag racers :nuts:), although a lot of the racing guys do consider them consumables. Would the MSM axles be any less of a consumable? Especially since they're NLA, rebuild only parts? Or should I just stick an OS Giken in my stock housing and call it a day with my power goal? What about the V8R Getrag kit?

I thought the standard torsen was good for 300+. Subscribed for when someone who actually knows what they were talking about chimes in :party:

MSM diff/axles are stronger than the regular ones, and less likely to break. If you want it, buy it. If you don't launch the crap out of your car, or let it wheel hop, you'll probably never break anything on a regular 1.8 diff/axle. And if you do, they're cheaper to replace and easier to find parts for.

I run a MSM setup, but for what I do to the car (break axles, diffs, crack subframes, almost pull front wheels off the ground on launches), the stock diff/axles wouldn't last very long. I've already broken a MSM axle, though not a MSM diff.

Yeah for what you're describing I don't see any need for MSM diff and axles. Assuming you have a Torsen, it and the axles should be completely fine for the uses you are listing. Wheel hop will destroy miata Torsens in very short order, but otherwise they're extremely tough; the transmission and / or axles are much more likely to fail before the Torsen, and not at the power levels you are listing.

For track use on a six speed I'd keep it to a max of 250wtq.

My 6 speed limit is 290 for hard use.

I expect it to be a consumable but without any major failures, so far none.

A few cars and some with slicks, all ok.

I'm on a full poly bushing set, and will be getting some Xidas to replace the old blown Konis soon, and don't plan on launching the car. Will have to find a better final gear ratio for the six speed and induction, though.

How gingerly would one have to treat a five speed to keep it alive at ~250 wtq? I can haz mechanical empathy. I ask because I've driven the six speeds and the feel is meh. Will go there if I have to.

My favorite summary is this:

https://www.miataturbo.net/attachmen...t-untitled-png

At the power point where swapping in a T5 and the Getrag comes in, that 6L out of a wrecked Escalade starts looking mighty tempting...

IIRC when Lazarus swapped in the msm drivetrain the 5 speed only lasted into the 2nd session with 235 wtq. Mechanical empathy won't save it, running that much torque on track will disintegrate the 5 speed.

Has anyone seen a TII transmission install that doesn't just weld angle iron to the ~20 gauge sheet metal in the tranny tunnel for a mount? I've found like four or five install guides that all do the exact same thing and it doesn't seem like something that'd stand the test of time.

Ratios look usable with my 4.30 T2 (looks like if I'm not launching or hophophopping I'm fine), and they won't grenade. The lack of a transmission solution was why I was limiting myself to 300 and a 6258 versus 300+ and 6758, since literally the only different parts in my build list would be the turbo.

Looks like the other option would be a T5 with the front half of a miata transmission adapted to it, as seen on the wine and cheese forum. There's a place in Cali that sold a kit with a shifter adapter and PPF mount, but no price listed, website gone. Was still sponsoring cars a year ago, though.

There is a kit on eBay. And TSE is also working on a kit.

Well, I'd call that perfect timing. I'm going to get the chassis and engine management sorted before boost, so by the time I'm ready to break the five speed TSE will probably have their kit out.

Come back in 2025

Surely you jest, it's not Begi I'm waiting on. Although the most recent stuff I'm reading on this is back in January with you, TurboTim, and Sav brainstorming shifter extensions.

I honestly would not expect anything to be on the market within the next year. Probably 2-3 years before we actually see something that is order-able. Low amount of demand coupled with high costs means it will not get rushed.

I need to make better progress on this whole MZR swap thing. For like a grand more than a full engine build and a 6 speed you end up with a 400hp capable 2.5 liter with a t5 behind it and a dry sump.

For a grand more than a full engine build and a six speed (let's say $9k) you'd be one wrecked GTO away from a 1000hp capable 400hp stock 6L V8. ($7100 V8R kit, $1000 L92, $150 Getrag)

As to the kit, it looks like front-halfing a Miata 5 speed gets you all the good hard to fab bits, even the TOB surface. Shifter relocation isn't anything new in the T5 world, and you guys have found a ton of working examples, it's just dialing in the miata-specific fitment. and the PPF mounting.

We'll see who gets there first. If I need to run a six speed with the boost turned down for a while, so shall it be.

Built engine from TSE: 2600+shipping.
6 speed: 600+shipping.

3200+shipping and other odds and ends. <$4k still

You're a little off with 9k.

I went with the $7000 Supermiata Big Whammy build and figured $1000 for a six speed, since I didn't see one on the bay. Remembered them being like $500-600 a few years ago.

$7000 whammy build is a horrible comparison. You can build a 400hp setup for much much less. Thats a race engine.

2600 for a fully built complete engine? where do I click pay?

I love these stupid discussions about prices. One party always overbudgets, and the other always claims absurdly low and cheap prices, omitting all the nickle-n-dime stuff and counting labor as free and timeline as unlimited.

at least the overbudgetters are not setting themselves up for failure and more prepared

Well would you look at that. TSE built engine is now 3100.

Come on Vlad. You know a LS swap isn't even close to a turbo build in price.