stick

Im trying to dtermine what kind of compression I should be going for with my setup.
I have a 99 head with oversized valves, deshroud, and port and polish
I have a stout bottom end and Im just trying to figure out the piston to go with.
the car needs to be able to run on 91 octane and is being built to be powerful and reliable. I want to be able to drive cross country in it without having to hunt down special and expensive fuel.
any recommendations???
what kinds of compression can a miata with a similar build and fuel requirement take.
im also open to other resonable suggestions
thanks,
stick
and yes I realize this is a turbo forum but this is also a legit place for information not just opinions

Braineack

iTrader: (62)

why do you want to spend so much money to be so slow?

nitrodann

Brave...


Very brave.

Props given for bravery.

Dann

nitrodann

F'n ninja'd.

Dam you brain

Dann

Leafy

iTrader: (1)

Running 91 you're not very serious, I'd just run stock cast pistons. If you were running 93 I'd say VVT pistons.

thenuge26

iTrader: (2)

Brain you just aren't baller enough to spend 10 grand for 170whp. Instead you spent a quarter of that for 230 whp.

That's why you're not madjdmtyteyo.

NiklasFalk

iTrader: (1)

11.8:1 here with ST pistons (rounded edges) on 98 RON (about your 93) with 36 degrees ignition. So I assume you can go quite a bit higher than 10:1 on 93.

To OP:
Is 93 that rare?

What kind of piston options are seen as doable (OTS, scrapyard, Custom)?

Sean

iTrader: (12)

I am not 100% with the miata motor but I had a 1.6L single cam honda motor running 11.5:1 on 93 pump with total timing at 31 deg drove the car to and from work every day no problems no knock. I would have to agree that after doing it it is a waste of time boost is the way to go unless you really just like NA. Also I was using stock honda pistons just from a different engine to get that compression, combined with a decked block.

miata2fast

iTrader: (2)

Do not go with anything less than 11:1 if you are building a motor. You need all the compression you can get in an N/A configuration. You will have to accept the fact that you will have to run premium fuel. On long trips, an occasional lesser fuel will be ok if you keep your foot out of it, and have it tuned properly.

Most people that hate on a well built N/A car has never driven one.

Sean

iTrader: (12)

I don't hate on NA cars I loved my single cammer jammer with high compression motor it kept up with most swapped hondas and was very very responsive. What I do know is I put a boat load of time into making it work and it worked great when the car got wrecked my new car had a stock b18 I boosted for way less than I built my motor for and was much faster. I had to run premium in both cars both have their own problems if I did it again I would build a 11:1-11.5:1 engine with boost that would be awesome.

Leafy

iTrader: (1)

I've driven a well build 99 engine miata, and after only having driven my tired 94 for a while it was holy **** fast. Then I put the vvt engine built for boost in my car still N/A and thought that was surprisingly quick too. Then I put the boost on low and realized even that wasnt all that fast.

concealer404

iTrader: (3)

This might be the only good thread on CR, but here you go.

My 172whp N/A Engine. Stock bottom end. No Porting. - ClubRoadster.net

That's pretty much a "how to do this for dummies."



Also, it takes someone with a non-functioning frontal lobe to consider an n/a build.

18psi

iTrader: (76)

The only cool part of a well built n/a car is the ability to flog the daylights out of it on the track and still be able to drive home 10 times outa 10.

Anywhere besides the track or tight technical mountain roads, its BOOOOORRRRIIIING!!


Back on topic though:
I'd say 10.5:1 or so would be the limit on 91 if you want to absolutely be dead nuts reliable and not worry even when you come upon that one bad batch of fuel in your travels. (a bad batch of CA 91 may as well be ****)

concealer404

iTrader: (3)

I would agree.

That said, ITBs can be a gigantic pain in the ******* ***, so i would consider them to lessen that ability.

I'd rather duplicate Quinn's build, but with a sheet metal manifold tuned for the powerband/RPMs that the motor turns for simplicity's sake.

There's videos of that car out there. It sounds epic, and seems pretty quick. He says it's at least as fast as his S2000.

Leafy

iTrader: (1)

If executed proper and fully tuned they should be set it and forget it baring any sort of fatigue breakage or bolts loosening. Of course if the car is a daily driver its going to take you a year to fully tune it.

concealer404

iTrader: (3)

Well exactly.

Then figure re-sync them once or twice a year. Then hopefully your ecu will handle weather/elevation changes well, because ITBs hate that ****.

Blah blah blah.

In the end, it's still cheaper and easier to go with a sheet metal manifold, and unlikely you will lose any power.

You just won't be able to tell anyone about your mad tyte y0 ITBs.



Sincerely,

An ITB'd car owner.

miata2fast

iTrader: (2)

I think much of the sync issues stem from crappy linkage components. Once you learn how to tune it properly, it can be done very quickly, it is the learning curve that sucks so much.

For a conservative power goal, I will take a healthy N/A over an entry level to moderate turbo set up any day.

As far as the OP's inquiry, I would say that anything less than 11:1 is for people that do not have a clue about cars. Nothing wrong with managing a little risk to gain more power. If you have some know how and are vigilant, 11:1 is a cake walk.

18psi

iTrader: (76)

What an ignorant statement.

Have you ever tuned high compression cars for track duty on AZ, CA, NV or CO using a bad batch of pump gas?

No? Then kindly put a cork in it.

Leafy

iTrader: (1)

Well its not his problem that you live in a stupid state and are too stubborn to move.

18psi

iTrader: (76)

lol

the reason I'm making a stink about it is because of this.
91 is not 91 is not 91 everywhere