You can get bad gas anywhere, though...

11:1 on an n/a Miata is just fine on 91 octane.

 

Alright we'll just agree to disagree then. I'd rather have the ability to raise timing because the car is running like a peach and hasn't produced a single knock event in ages rather than drive around constantly trying to listen to the motor and hoping that the knock sensor picks up the noise and pulls timing in time should that happen. (or run little girl timing because i r scurrd)

 

I'd just prefer to not build an n/a Miata in the first place.

 

I love it when you talk dirty to me.

We are not talking a big motor here, and 11:1 is not a lot of compression. I was implying that someone who knew what they were doing would tune appropriately if the situation was risky, say a very hot track or a long distance trip where fuel could be questionable.

Cake walk.....

 

 

OP what is your power goal? I would say for NA doing what TSE does (10:1 + VVT + squaretop, maybe shave the head for more compression) is the way to go. If you need more than 150whp, then get a small turbo. Is there a reason you want to stay NA? A 180whp turbo car will be a lot more reliable than a 180whp NA car.

NA, powerful, reliable on CA 91. Pick 2.

 

Says the guy running carburetors on a miata.



I kidd. Seriously though a lot of this depends on where you live. Are you at sea level with dense humid air? N/A can be very enjoyable. At 7,200 feet in the desert/mountains where I live? Boost is a must have. ****, 4psi of boost gets me 105kpa total. I literally don't make make any more power than a stock miata at sea level until boost pressures are over 4psi.

 

Why don't you run E85? There are a metric fuckton E85 stations in Chicago.

 

The big problem with ITTB is that they really don't like air filters. Something about laminar air flow. A bunch of power gets lost when you start getting in the way of the horns. That being said, I would go to a custom single hole manifold or a square top.
I love my ITTB setup and have no tuning issues like so many, but if I had to run an air cleaner I would run something different.

 

Optimally you'd have a sealed plenum around the velocity stacks and would be feeding it cold air and have a filter before the plenum.

 

Filters are for pussies.


Roll boss status.

 

and when it rains, you get water injection.

win win

 

I have a separate timing map for rainy weather. It's super awesome.

 

thanks for the amusing thread. the reason i wont turbo is because i love the sound of the itbs i have already built a more stock motor with them, now i want something a little more serious. I want to have power and to be able to use it. im not like some people who dont know their own limits and think more is better even at 400 horsepower. these people tend to wreck their ****. ive seen my car get quick just by having the right coils and plugs. ive seen what modifying the cas sensor can do for drivablity. I want to refine what is there not throw a turbo at it and call it a day.

where most people use a five pound sledge i find myself using a finish hammer. If you know what i mean.
I hope offend anyone.

 

now to get to the point. have been told by a realiable source that 10.5 is the most you can do on 91 fuel i will be using a knock sensor and map but i need some input on the known limitations of similar setups to mine to have a decent starting point.
thanks

 

do you do exclusively canyon carving or track in this thing? cause then your statements would somewhat make sense (though on big tracks you'd still get left in the dust by the turbo boys)

as to your most recent post:

what exactly are you asking about? which limitations? power? what..

having only glanced at your vague description, I'd guess 140-170

 

^This

Ive heard about drag bikes picking up several mph trap just from adding an airbox, and they were not running filters to begin with.
The only reason we see so many open throat IRTBs is because people think it looks cool.

 

What's the reasoning that there's only a half point leeway between stock compression and blowing your motor on 91 octane? That doesn't make sense for quite a few reasons.

 

lolol her we go again

I have personally made a 99nb with 01 shortblock knock on a very hot day on pump gas with a lot of load (going up some mountains). Stock everything else. And that's 10:1 only. It is very much possible

 

Ive seen 14.0:1 CR on 93 octane... so yeah...

Whoever thinks 10.5:1 is the maximum static CR on 91 octane is probably a domestic guy who is used to garbage wedge combustion chamber heads and low duration cam profiles.