Talk me out of this...Please

Since the engine decided it was going to blow up in my miata I've been debating on what to do with it. Thinking about the car and what I like about it, what I dislike about it. How to correct those things. What motor to go with? Another 1.6, or 1.8, even FE3(boosted on all these options). LSx would be great, just out of my budget right now. Besides I'm wanting something that is good if not great on gas, reliable, and comfortable enough to get in and road trip with.

Biggest thing I've come to dislike about the car, 3300rpm+ on the interstate. I've taken road trips with this car and as long as I stay on the back roads with speeds under 60 the darn thing gets 30+mpg but as soon as you hit the interstate it drops to 20ish. That's with 205 width azenis on it. 225 toyo's were even worse. My old 3rd gen F-body got high 20's on the interstate, sucked around town, but that was likely my right foot(I was 18).

Since the motor popped, I've been looking at bimmers to replace it with as a daily. One of the things that stuck out in my mind is the numerically lower rear end gears it seems most of the more mundane 3 series cars run(not talking m cars), and just about everything I read on forums people claim to get 30mpg or better interstate driving out of em.

I'm wanting to build something that puts down at least 300 to the wheels. The breaking point on the miata 5 speeds seems to be around 250, and though I haven't found much on em the six speeds seem to be stronger, yet they still break, and you gain next to nothing with the extra gear.

So the big questions and thoughts are, adapting a 3 series rear to a miata, how much of a pain in the butt are we talking about? How much power can they handle? While I've looked at and researched rear end, diff, and ring options that readily bolt into the miata, they all come in as expensive. Complete torsen swaps can be had, but then looking at a lower # ring and pinion and lowest readily available is 3.63ish (the 3.36 is unubtanium)while you're doing that you might as well replace the diff, which costs even more money, blah blah blah. Numerically lower gears are common with lsd diffs in the bimmer world.

Next question is the BMW E36 6 speed, geared for the lower ring and pinion numbers and strong enough to be put behind the M3's, but how much power can they take? Having never seen one in person I have no clue on how big they are physically or what kind of shift linkage they use, or where the shifter is located. Theoretically I would need an adapter, a clutch disk splined to match the input shaft, and figure out the throwout bearing(was thinking ls T56 style honestly) But will it fit in the tunnel?

That leaves how to adapt the power plant frame? Custom driveshaft, and drive axles.

Engine wise, I'm leaning towards the FE3, the swap is becoming more and more documented, the bottom end is supposed to be good for 500 or so hp. Mild porting on the head, oil pan, custom intake mani, boost, and boom should have my power numbers. Now to figure out the rest.

Hopefully this is understandable, trying to put down what's been running through my head for the last month in one shot is rough.

E36 six-speeds are euro parts that are hard to source. I suspect they are the same as the E46 M3 ZF 6 sp trans can take more than the stock 262 ft-lbs the S54 is rated at. I don't know what the limit is but an S54 with a twin-screw blower won't break it.

When you are asking about driveline - forget HP. Torque is what breaks 'em.

The 6spd + 3.63 isn't bad on the highway... better than what you said you were getting before.

The 6spd is also very easy to attach to an FE3.

Spinout007 wrote: [...] as I stay on the back roads with speeds under 60 the darn thing gets 30+mpg but as soon as you hit the interstate it drops to 20ish. [...]

I usually get 29 mpg going 70-75 mph on the highway. 32mpg on back roads. I've got a stock 1991.

Monster Miata drops in the Ford 5.0 (ok, 4.9) so there is some experience and parts for that swap.

sounds like a trainload of work for a little gain

readjust your power goals only a little, and you can keep the stock transmission.

i don't know, but somebody somewhere has got to have a different ring and pinion for these 1.8 diffs. that'd be the only thing i'd mess with.

belteshazzar wrote: sounds like a trainload of work for a little gain readjust your power goals only a little, and you can keep the stock transmission. i don't know, but somebody somewhere has got to have a different ring and pinion for these 1.8 diffs. that'd be the only thing i'd mess with.

http://solomiata.com/RingandPinion.html

Spinout007 wrote: Biggest thing I've come to dislike about the car, 3300rpm+ on the interstate. I've taken road trips with this car and as long as I stay on the back roads with speeds under 60 the darn thing gets 30+mpg but as soon as you hit the interstate it drops to 20ish. That's with 205 width azenis on it. 225 toyo's were even worse. My old 3rd gen F-body got high 20's on the interstate, sucked around town, but that was likely my right foot(I was 18).

Yep. The Miata is a great sports car and race car but sucks as a DD, IMO. In part due to the rpm but also the lack of space is sometimes annoying if it is your only car.

On the flip side, you won't get much better than 25 mpg on the 5 speed e36s. I never got more than low 20s in mixed driving.

You can get a Miata engine pretty cheap - like $500 - from a JDM importer. Some locals have used this one: http://attarco.com/products-page/used-engines/mazda-b6-ze-used-engine/

I have thought about the Ford diff from a T-bird or Cobra. Pretty wide open on ring selection and lots of lsd options. I've got a pretty decent line on a motor/car from another grm member to get it back on the road, just thinking about the future and debating on the direction with it. I'm just worried about the miata 6 speed's ability to hold any torque/power the FE3 is pretty much a given on the motor I want to go with. The 1.6 is like I said to make it go down the road. As for space and luggage capacity with the miata, I have no trouble packing a weekends worth of paintball gear/supplies in it. Tent, chairs, gear. But that includes using the passenger seat.

Or do I just give up on it for now, and purchase an E36 or high mileage E46? As a good E30 will pretty much run as much as an E36

I think you would appreciate the extra space an e36 or e46 offers. Both can be pretty awesome DD/fun cars while offering ample storage space.

For Sale: turbo miata and I'll include more fun than you every thought possible with clothes on. Needs work.

V8 Miata: Not as much fun, not as much stress. More $$$

The real answer: t-bird diff in your miata - appropriate ratios available and you won't break it (even with a butt-load of boost.

The M3 will do 30mpg @ 3200rpm cruise if you keep your foot out of it. The V8 miata will do 27mpg (guess what?) if you keep your foot out of it. The turbo car could get over 30 mpg (w/ 4.10 gears if you could kkeep your foot out of it.) M3 not for sale at any price, come and get the others.

I'd second (?) the M3. I've mentioned it before, but I just got a '95 for $5500 with 150k. Lots of miles but anecdotally, they go a long time. And I just feel good when I'm driving it. It's old enough that you don't get the BMW douche look from other drivers. I'd guess that the M models were better taken care of than the lesser models were, and that in itself is probably worth the higher price.

If miata, I've heard you can get the CTS diff that Flyin' Miata uses for less than $800 off the shelf brand new from the GM dealer. Plenty of ratio options there.

Lots to keep thinking on....

Love the M3's - I think I regularly got better than 27 mpg on the highway (don't forget they use premium fuel in your calcs). Fantastic all-around cars. I have a vert right now, but recommend the hardtop. I've been fighting glitches with the power roof, and find that the hardtops feel a lot more solid.

All that said, if you were a local, I'd be knocking on your door to purchase a miata with a blown motor.

DavidinDurango: what V8?