Couple of quick questions about buying a pre-turbo'd Miata
 

My buddy (a longtime friend) has recently bought a 1991 Miata with a GReddy turbo kit and can no longer keep it (needs a truck and to keep his DD so one car - the miata - has to go). I'm planning on buying it because of how insane of a deal it is (4k for a car with a cage and a hardtop, new tires/wheels, and inspection and is turbocharged - can't beat it)

The Greddy kit runs 5.5psi and has the Vortech FMU on it and a front mount intercooler (some ebay one I think) but the kit is otherwise stock with an aftermarket fuel pump, Walbro I believe.

I'd like to know what the 1.6L can handle whp-wise, I plan on upping the boost after I buy it. I know it'll need injectors and something for engine management (thinking e-manage ultimate) but what can the stock motor handle?

Thanks in advance.

250 is usually what u can expect the greddy turbo to handle.

ok thats fine, however what will the MOTOR handle?
ie if I want to upgrade the turbo/manifold/etc - what whp mark should I consider buying a spare motor to build?

search perhaps? there are at least 25,000 threads discussing this.

anyways... it can support around 300whp is what everyone says. it all depends on how good your tuner is. get it tuned properly and it will live for 100k+ @ 300whp.

I'll be nice this once.

To be reasonable, keeping power down in the 250whp neighborhood is good advice for longevity. Above that, it's not just the motor that is troublesome, but the stock cooling system, brakes, suspension, and all the other parts of an OEM car when you add 2.5x stock horsepower.

But yes, a healthy BP motor should be able to make 300whp with all the supporting mods for a reasonable amount of time. It's not gonna get you to 100k miles, but it's not hard to make the power.

Your Greddy kit is probably putting down in the 145whp neighborhood. The no-brainer choice for Miata ECU's is Megasquirt. You can be fully up and running with EBC/MafDelete/LC1/Standalone for $1k with 12x12 fuel and spark and all the support you'll ever need to troubleshoot on this forum. Throw in some used RX7 460's and be good for 250whp for fuel.

Your Greddy system now is hampered by an IC. A decent IC will let you run about 2psi more boost. Then it'll be hampered by timing. A Bipes timing retard device will get you up to around 8psi. Then a set of Supra 305's will let you run in the 12psi neighborhood for 200whp at around 100psi of fuel pressure. Add an 02clamp for good measure and you are Bandaid Complete.

Or you can just get a Megasquirt and ditch the Greddy FMU which will never have the fidelity to let you run over 200whp in a manner you'll enjoy.

To start, you need a compression/leakdown test to assess the health of the motor. Don't bother doing anything else until you get those numbers. No sense throwing money after a motor with bad rings or a crap valvetrain.