bang for the buck engine build for turbo miata

I'm thinking about building up a turbo engine for my 95 miata. I have no problems with the current engine, it only has 70k miles.

Ultimate goal is to be dead nuts reliable track/autocross toy with about 240-250 hp. (I've done a ton of reading on what it takes to get a turbo miata to do that)

I'll use a megasquirt, since i'm familiar with those. I mainly have two questions

1. if you build a mix and match frankenstein engine, with reasonably priced upgrades, is there a big enough advantage rather than just slapping a well worked out turbo package on the stock 95 engine?

2. what would such a build consist of?

Wait for keith to come in but I do believe the miata rods get a bit noodly at 250hp, if your looking for dead nuts reliable you would need hbeam rods. Theres plenty cheap ones on ebay if that's your thing just have a shop check the big and small end sizes first. And a coolant reroute.

would I need the H rods, or would the $400 cheaper A rods be ok?

Ebay/K1 rods, and an FM2 kit.

What year head should I aim for?

250 whp, or 250 hp? I had no issue with my rods, making 235 whp. Put almost 75k on the motor turboed. And didn't put the turbo on until almost 100k.

Now the stock piston rings.... Those eventually went, from running 15 psi.

icaneat50eggs wrote: would I need the H rods, or would the $400 cheaper A rods be ok?

Depends on how good the rods are. Personally, I'd just use a healthy stock Miata engine and spend my time making sure the tune was good. That'll be a lot more effective. In other words, just put a good turbo setup on what you have. And "good" may mean "pre-engineered", as there's a lot that gets glossed over in forum discussions.

1999-00 head will flow best for the least effort. If you want to learn to control VVT (and put in the dyno time to make it work best), go 2001-05. Least expensive would be 1994-97.

I kind of want to do similar, however my car is a 1.6 to begin with and I want to keep power below the threshold that miata trans start breaking which I think is around 230ish. I'd love 230 wheel with a good torque curve for autocross.

I have been thinking that my 1.6 wont be the way to go which has had me looking at stuff like the ECOTEC swap but I did notice the FM2 kits seem to have come down in price? (to 4k something thought they were over 5k before)

I think the price has stayed the same but the new website makes different things optional upgrades

FWIW at the track last month the 200-250 hp Miatas were great.....for about 10 minutes and then they would get too hot and have to pit. I went and looked and they appeared to have all the right stuff (heavy duty radiators and proper ducting/vents/etc) but generating more than double the hp from stock created cooling issues. I'm sure it can be dealt with if done correctly (ask Keith) but it is an issue to be aware of.

In reply to KyAllroad:

I bet none had a cooling reroute...look into it, mazda engineers made a mistake when making a fwd engine rwd. Coolant enters one side of the head, doubles back and comes out the same side as opposed to going in one side and out the other. Makes even stock miatas overheat when driven hard.

The price of the FM II hasn't changed in years. So yes, it is getting less expensive in real dollars. The new site does allow you to play with options that weren't listed before, though, such as bringing your own turbocharger.

A big radiator isn't a guarantee of a good radiator. Coolant reroutes can help, but they're not going to prevent cooling problems caused by an inefficient radiator or bad airflow. Ducting on the front end isn't all that much help if you haven't done anything to get the air out.

Best thing you can do to help a track Miata stay cool is to ditch the AC.

KyAllroad wrote: FWIW at the track last month the 200-250 hp Miatas were great.....for about 10 minutes and then they would get too hot and have to pit. I went and looked and they appeared to have all the right stuff (heavy duty radiators and proper ducting/vents/etc) but generating more than double the hp from stock created cooling issues. I'm sure it can be dealt with if done correctly (ask Keith) but it is an issue to be aware of.

I had a 220 rwhp turbo Miata that saw a lot of track time, and it is possible to get enough cooling. In a word - oil cooling. The mouth opening is small, so I went with a Racing Beat Type 2 nose (for the two little extra openings on either side of the mouth) and used twin oil coolers plumbed in parallel. Also, shifting at 6800 instead of 7200 rpm helped a lot. The oil temp gauge seemed to function as a cumulative revs meter. Worth the effort to pass a Viper!