btw its not like i held it at 12 psi for a long period of time. i let off as it was hitting 12. so maybe 5seconds of 12psi no knocking, no odd nosies. sounded like normal.

How many times does a motor spin per second at whatever rpm you were at? Now multiply by 2 as thats how many combustion cycles happen per revolution on a 4 banger.
Thats how many lean combustion cycles you ran in those 5 seconds. Heat doesnt have to knock to melt shit.

You might want to start by reading the stickies.

I would support a rule that banned members who use arbitrary boost figures as the "limit" for anything inside the motor.

Boost is an arbitrary measurement of intake restriction. I guarantee that 12psi from a GT47-88R will grenade the shit out of a BP so fast your head will spin, but a GT1248 making 12psi would be barely noticeable.

Boost is literally the most retarded way to measure the strength of a motor. It's only slightly better than horsepower ratings. Engines are rated for torque, and more specifically combustion pressure. If you had some crazy turbo setup that made 500wtq at 2500rpm, but only made 190whp, and did it all at 10psi, would the "motor holdz 15psi bro" crew say that a stock BP would hold up to that abuse?


The motor won't hold up to 15psi, or 20psi, or 2psi, or 7289375843q2098q7209834psi. It will hold up to approximately 230-250wtq, depending on your tune and usage. Or you'll melt the everliving shit out of the pistons running 90whp on the track, if you don't have a wideband and you're running 14:1 at WOT.

Like others say, crank it up to 20 psi, there is no limit!

Like stated, buy a compression and vacuum tester. Check your sparkplugs...

What is the gap in the ones u have?

Buy NGK7 or NGK8, those platinum +4 r junk.

What r the settings in ignition timing?

It is good to at least do the compression test to have a default number to work from, the same goes for vacuum. Install a oil pressure gauge, what r the readings at idle?

"slightly better fuel pump"???

You are lucky that engine is still running... dont raise boost.

Yeah, that was a good wideband, make sure the sensor is included when buying on EBAY. Have the grounds as much as possible to the engine block, do not install the sensor close like a O2 sensor, give it like I said, like 2-3 feet from the turbo (exhaust side).

Can you post exhaust size, 2.0/ 2.5/3.0?

Intercooler? piping size?

The motor won't hold up to 15psi, or 20psi, or 2psi, or 7289375843q2098q7209834psi. It will hold up to approximately 230-250wtq, depending on your tune and usage.
posted by Savington...

Of course!

But basing it on where he is at, and where he wants to go, he must take care of several details before continuing to increase boost.

See this is what bothers me. I've accepted it because its said however still doesn't exactly makes full sense to me. If you have steady 12 psi then when the pistons open up they will fill up with 12 psi, no more no matter how much that turbo flows as even if that turbo flows 50 gallons a second it cannot get above the 12 psi road block. What makes sense to me is each piston can only be filled 100% with 12psi. For more the pressure would have to be more than 12psi. If the gt1248 fills the piston up to 100% of the 12psi and the gt47 does that also how would it blow the motor up (assuming the wastegate or boost creep is no issue)

In order:
-Increase size of turbo
-Increase size of turbine housing
-Decrease backpressure
-Lower backpressure means that the pressure differential across the exhaust valve is higher during the exhaust stroke, which means...
-once the intake valves open, the chamber pressure is lower, and therefore the pressure differential across the intake valves is higher, which means...
-the larger turbo will more efficiently move air through the system at the same boost level

More air = more power

More power = more broken shit.


The ultimate example of this is with a supercharger. Superchargers produce boost keyed off the crank, so let's say there's a Honda with a Rotex that makes 12psi at redline and about 275whp. The owner decides to put a camshaft in that typically makes another 30whp. He installs the camshaft, boost levels DROP to 7psi, and the car makes 350whp. Did the flow go down? No, it went up dramatically - the camshaft reduced the pressure in the intake manifold drastically, but the power went up anyway.

Less boost, more power, more broken shit.


Boost is only good for comparing the SAME turbo at Xpsi vs Ypsi. It has a convenient correlation to flow, as long as everything else stays the god damn same. Once you change the turbo all bets are off.

Yes I have fucktard. Never on my own cars though cause I'm not a fucking moron like you. Then later the owners of said cars came back to me because either they were tired of the piss poor power they were making or because they broke shit and/or needed to diagnose a bunch of issues. Eventually everyone goes with a proper setup. The dumb ass ones just take longer to realize the truth. Hell, you're still in denial.

HOW MUCH BOOST YOU RUNNING BRO? OH SHIT 12? WELL THE LIMIT IS 13 SO YOU SHOULD BE GOOD


DERP

Fuck are you serious? I'm at 14?!!!!!!!!1!1?1?1!?!??1!! Shit shit shit shit....


Brb...gotta turn down the boosts to 12....

Lots of misinformation in this thread, and I'm sorry mazpr, but your MegaSquirt thread doesn't help your credibility. Your enthusiasm is very welcome, however please realize we've all been corrected by a more knowledgeable person before. It's how we learn, don't take it personally, no matter how harshly they point it out.

The bending rods is a little off topic, 12 psi is well within 250 - or even 200rwtq - and is plenty safe as long as he has a good tune, which was his original question.

2.5 on the exhaust, and 2.5 on the intercooler piping. its a little leaky at the moment. my best friends dad is also my mechanic and has the stuff to do compression test, he has the time to do it tomorrow. quick other question dosnt the MS have a wideband built into it.

Kind of... You need the actual wide band sensor. From there you could wire it up to the MS and see your A/F ratio on the laptop in tunerstudio. But no one keeps the laptop up and displayed 100% of the time, so it's best just to get a gauge. An AEM one can with sensor can be found for $120.

Thanks for the detailed explanation Savington. So basically it all comes down to filling that cylinder up to 100% of whatever boost your running.

Smaller turbo would fill it up to only 80 so 80% of 12 is more like 9.6psi actually making it to the piston while a bigger would go to 90 and so forth...

That's not a good way to think about it. You don't fill a glass of water with 14.7psi of water - you fill it with 8 ounces of water, and the pressure inside is 14.7psi. If you have flowbench numbers from the cams at various lifts, and you know the duration of the cam, and there's 12psi of pressure on the backside and you assume some pressure in the cylinder, you can sit down and figure out how much air will flow through them at a given RPM.

You don't fill containers with pressure - you fill them with volume, and they exert pressure.

No, not even kind of. That's like saying the Megasquirt kind of has a cam angle sensor on board, since it can read the signals that are given to it from a cam angle sensor.

The MS will DISPLAY the readings that you feed it from a wideband CONTROLLER. The controller gets its readings from the sensor. The controller is the big black lump in the LC-1 kit, or it's built into the gauge in the AEM UEGO kits.

I don't care if your fuel regulation is a pair of vise grips on the return line and you manually squeeze them every time you go into boost - if you don't have a wideband, you are playing Russian roulette every time you put your foot down.

I was thinking more along the lines of the AEM inline controller, but figured they would be cheaper than just going with a guage. So yea, kind of, you can display your A/F in TS with a MS, but it won't do it alone.

Sometimes, you have to infer what is being asked. Somehow I doubt that he actually thinks that the MS has a wideband sensor inside, unless he also thinks you mount the MS in the exhaust. Which at that point, I give up.

You guys rock :bowrofl:

Thats definitely sig worthy.

I loled.

let me rephrase i ment as an add in, or displaying from the o2 that is already on the car. i was thinking about buying the unassembled kits there allittle bit cheaper what all is needed besides the kit.

https://www.miataturbo.net/attachmen...ine=1315246817
Cyl 1
https://www.miataturbo.net/attachmen...ine=1315246817
Cyl 4
They look good to me.

Are you really posting pictures of your spark plugs to convince us that your tune is good and you don't need a wideband?