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Old 01-03-2009, 01:49 PM   #1
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Default NA or NB which is better to turbo?

So I am new here and have 2 cars as potential donors. I was going to build a SM out of one and possibly build a streetable fun car out of the other.

What can I expect to get in the way of HP out of each and is one easier than the other to mod for a strong turbo?

I thought about installing a turbo Rotary but I think I would end with a headache from all the modding and expense so i am going 1.6 or 1.8 turbo.

Thanks in advance for the responses.

Ole
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Old 01-03-2009, 01:52 PM   #2
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Lots of opinions and options out there. An old 1.6 car will be cheap and reliable boosted. But after owning about a half dozen NAs and now with an NB, I'll be the first to say that the NB is a superior car in every way with exception to the NA having a little more interior room.
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Old 01-03-2009, 02:05 PM   #3
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I have no complaints with my 1.6L. And I'm still running the stock rearend. It is all about your goals. Both cars have the same rods. There isn't a hole heck of alot of weight difference. The 1.8L has some extra displacement and a larger rearend.
and 1 inch larger rotors.
Turbo the nicer car for street. If you only have a $1000 budget, i would go 1.6L. You can use a greddy kit.
If money isn't a object, I would do the 1.8L.

If it where me, I would turbo both. A used greddy on the 1.6L. Baidaids and low boost to be a dead reliable to work car.

And make the 1.8L the beast.

Either is capable of 250hp. The 1.8L is easier to get more hp out of.

One guy on here has a 300hp 1.8L. But he has custom tailored dp and etc.

I like the 1.6L for the availability of cheap parts. The 1.8L turbo stuff is a little higher. But when it all comes down. The 1.8l car is a better platform, if you are going to run stock brakes and everything.
With that said, I have no issues with my brakes.


Both are good. And if you already own both, I would probably do the 1.8L car. But if you are buying a car, and they both are very nice, and there is a turbo kit price between the differance. You have to consider that too.

Last edited by Toddcod; 01-03-2009 at 02:15 PM.
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Old 01-03-2009, 02:34 PM   #4
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Strong turbo? Do you mean for 50%, 100%, 150%, or 200% more than stock HP?

BTW those HP #'s in the above posts are rear wheel HP. These guys usually only talk WHP whereas most other places are talking flywheel HP (engine HP). Add 20% if you are trying to picture engine HP.
300WHP = 360HP ; 250WHP = 300HP. And yes, that's quite a bit in this chassis.
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Old 01-03-2009, 02:34 PM   #5
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Two schools of thought here.

All else being equal, I'd say you should make the NA into the race car, and the NB into the street car. For SM, a 1.6 NA will be cheaper and easier to work with. No restrictor plate, parts are cheap and easy to come by, etc. And for the street, the NB is a better car. The chassis is a bit stiffer, so it's smoother and quieter. It's already got the larger diff gears so the diff will better survive boost.

The only thing that would muddy this decision, for me, would be if you live in an area where emissions testing is performed by OBD-II plugin for '96+ cars. It's not impossible to turbo an NB and keep it passable, but you do have to be a bit more careful. No full standalone ECUs, for instance. And in general, they do have more parts on them specifically designed to help you fail a smog check.
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Old 01-03-2009, 02:45 PM   #6
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I am leaning toward adding the turbo to the NA car because the NB is a better car for SM. I expect that soon there will be a seperate class for the 1.6 cars in SCCA and I already have 2 of them. The NA donor has the factory L/S diff that will eventually be replaced with a Torsen (I'll wait till it goes out). The NB car already has the Torsen that will work for SM.

If I take the 1.6 and bore it to 40 over should I go with 8.5:1 compression? I have read that will make a bit more reliable. I have access to 1.8 injectors as I have a ton of parts for both cars (been racing for 4 years now and accumulated a few cars as parts cars). I have also read about the Rotary injectors working better than the 1.8 injectors, any thoughts on this?
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Old 01-03-2009, 03:11 PM   #7
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Food for thought:

NA is OBD-1 so easier to pass emissions if you are in a pain in the *** state or don't have access to a "friend."

NB 1.8 has a better flowing head and depending upon the year, possibly slightly higher compression which in combo with the 200cc of extra displacement lead to earlier spool and ultimately more HP with the same turbo/boost level compared to the NA.
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Old 01-03-2009, 03:19 PM   #8
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I live in No. VA. if that helps. I can register the car WV where my garage is. No.VA. is a pain in the rear as far as emissions.

I have updated my sig and other info....well I thought I did
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Old 01-03-2009, 03:28 PM   #9
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OBD-I has its advantages that I had not thought of. Can I get 250 HP out of a 1.6?
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Old 01-03-2009, 04:25 PM   #10
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Quote:
Originally Posted by wwracing View Post
If I take the 1.6 and bore it to 40 over should I go with 8.5:1 compression? I have read that will make a bit more reliable.
If you hae to bore it anyway (damaged bores) then you might as well go for the lower CR. It's not a big enough difference to justify doing it for its own sake, in my book. I'd wager than >95% of us running turbos on our Miatas are doing so on stock pistons.

Quote:
I have access to 1.8 injectors as I have a ton of parts for both cars (been racing for 4 years now and accumulated a few cars as parts cars). I have also read about the Rotary injectors working better than the 1.8 injectors, any thoughts on this?
The 1.8 injectors, depending on which year they came from, could be 245 or 265cc. The stock 1.6 injecors were 230cc. So as you can see, this is a trivial increase.

RX-7 injectors can be found in 460cc and 550cc versions. Both are excellent for the 250HP range. Obviously, you will not be able to run an injector this size on the stock ECU, but there are plenty of us doing it on Megasquirt, as well as the old EMU.


Quote:
Can I get 250 HP out of a 1.6?
You can get 600HP out of it if you're not concerned about longevity.

Seriously though, the 1.6 will support 250 HP without too much trouble. It'll take a tad more boost to get the job done than with the NB (owing to the head design) but with a properly-sized turbo it's achievable.
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Old 01-03-2009, 04:36 PM   #11
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just buy whatever you can get the best deal on. it basically just comes down to which one you think looks better.
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