I've been lurking around here for a while. I have a 1990 miata I'm planning to do the 1.8 swap in it. I want to boost my car as well. will the 1.8 effect what type of engine management I can run on it? Or would it be better/cheaper to just boost the 1.6? (160,000 miles) The 1.8 I can get has (87,000 miles) and I already have the FM swap kit. Would the extra 200cc's make much difference in a turbo'd car?

 

It really depends on what your ultimate goal is. How much power do you want?
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1.8L - Faster spool more torque
1.6L - Already in the car

The difference is not much maybe a few hundred RPM spool difference. The torque i dont know exactly how much. If i already had the motor and FM swap kit i would swap in the 1.8. If i didnt have the 1.8L or any swap kit i would turbo the 1.6.

On the other hand what is the health of these motors

Compression test #?
Leakdown test?
Oil Leaks?



+1 on the above. What is your goal for the car. AutoX Track Drag

As well as what is your power goal? 150whp, 175, 200, 240? All of these are attainable on both motors as long as its in healthy condition.

 

Personally i'd just keep the 1.6 but i'm biased. Plus it seems like you already had you heart set on going to 1.8 with the FM swap kit. As long as have good compression in the 1.6 and no leaks, it willbe fine.

There are people making lots of power of both motors. With the mods I have, I can most definately out-spool alot of the 1.8's. It really all comes down to what you want to do. Engine management options are the same. Most people use standalones(i.e. MegaSquirt, AEM, Adaptronic, etc.) You just need to get the model designed to work with your car/motor.

 

Well as far as horsepower. I think a decent goal would be 200 hp. I use the car for some autocross , sno-cross, and on the street. It would be fun to drag it, but that can be really hard on your car. But racing typically is. The reason I seem set on the swap is that I picked up the FM swap kit at a deal I couldn't pass up. I have a 1.8 I can get for $350 from a known miata guy around here. My biggest thing is I don't want to turbo this motor at 160,000 miles then have it go out. And have to switch the motor later. But then again I only put maybe 8000 miles on it a year. I could sell the swap kit and have more money for the turbo. I'm indecisive I guess that's what it boils down too.

 

If all you're looking for is 200 whp I wouldn't bother swapping in the 1.8. Then again not many people stay at 200 whp.
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Yeah I've read that from just about everyone on here. HP is an addiction.

 

When I first turboed my car back in 1999 I swapped in a fresher 1.6L auto motor. Looking back I think not going to a 1.8l was a big mistake.

The 1.8 makes much more torque so it is more fun to drive. It also wont be working so hard to make the same power levels as a 1.6l . And for some reason if you track your car the 1.8l seems to cool better in my experience it seems a bit more reliable when flogged. Especially if you keep power level in the low 200’s Although I got good reliability out of my 1.6 and never blew it up I had real difficulty getting it to run hard for 20 to 30 minute track sessions without overheating if the turbo didn’t fall off first even with all the common cooling tricks. Whereas the 1.8 in the same chassis would do it without overheating.

Problem I think I have now I’s upgrading the 1.6l to 2l and power going from 200 to 350 creates more problems. Making the loud pedal cause intense pressure on your backside is addictive though.

Bob

 

Do you already have any 1.6 turbo hardware?
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1.6 turbo parts are far more plentiful and is easyier to come by used and cheaper.and you can always build up a 1.6 motor down the road.

 

If you don't have 1.6 turbo hardware, switch to a 1.8 now. There is absolutely no downside beyond the cost, and the extra 240+cc of displacement is well worth it. Look at what people pay for FM Stroker kits - that only adds ~160cc.

 

Cheap 1.6 used parts are easy to come by because so many people make the mistake of turboing an existing 1.6l rather than paying a few hundred more for a 1.8l swap while there spending all the money on the turbo bits.

You end up buying 2 turbo kits that way and loosing a lot more money than the initial investment cost to up the displacement in the first place.

Bob

 

There's no point doing a 1.8L if you're not building it and sourcing the right parts, so it's not a few hundred dollars more. you want the 99 head, and 94 block regardless of it being built in the least. then add in the swap kit and it's closer to an extra grand...

 

This ^^
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I agree.

Oh, and pay attention to the 94 block. I just made this oversight and sent my 96+ block to the engine builder not realizing it didn't have the water and oil ports on the side. Now I have to run my oil feed line all the way around to the intake side of the block. And I have a 94 block in the garage taunting me on a daily basis.

 

If in the short term you’re happy with low 200's hp. a salvage 1.8 will be reliable. And you have an upgrade path of going to a built motor later to get closer to 300 if you want more which you will.

I don’t care how much you spend building a 1.6 motor you still can’t get out of the mid to low 200's and still be reliable. And by reliable I men able to flog it at track days on a regular basis and still drive it on the street.

Bob

 

Any pics of this, or more explanation? Any workaround while it's still at the engine builder? I have my 97 block being prepped as we speak.

I think your point here is that with the extra power of the 1.8, you are going to be closer to having stock rod bendage and holed pistons, since they are effectively the same stock parts? Good point. But I was probably getting ~225whp on the right day when I twisted up the mbc on the B6, how close was I to failure?

On the 99 head, I did the 1.8 swap so that I could do the head swap later. The turbo exhaust manifold is the same between the NA 1.8 head and the NB head. The same can't be said for the B6. I ended up getting a '00 head anyway, but that's another story...

 

so you mean that a junkyard turboed 1.8 can be flogged on track days every weekend and be DD'd at say 220whp?

I am set on blowing up my 1.6, running alot of boost with water injection, and megasquirt... but i figured id just swap another 1.6 with the long nose crank in after this one blows up! however, i fully intend to abuse this car everyday as much as possible.
and if the 1.8 is better suited to that! i dont know if i can say no

 

The two motors are equally stout. Having said that, don't expect to flog a 220whp car at the track every weekend and have it hold up on a long term basis - track cars see more abuse in a single session than street cars do in a month or more.

There's an unfortunate belief that turboed Miatas are cheap, and they make great track toys. You can turbo a Miata for cheap, but if you expect to actually go to the track and drive (vs. go to the track and wrench) you're going to spend a lot more money than you expected to.

 

I love my 1.6 ...i think it revs quicker everything it lightweight & balanced . its making 289rwhp @ 17psi, but i could list what it doesnt have quicker than what it does... if i had to do it all again id still go 1.8 ,because the old saying is true...theres no replacement for displacement. if you start with a motor naturally making more horsepower it already has a head start when going supernatural.its not all ways higher ultimate power , but added displacement= quicker spool= a more aggressive powerband= female passengers cumming quickly upon swift acceleration! ++