How much boost - NA6 Turbo

[totti]

Hi guys

I have a NA6 with a JDM 1.6L longnose (standard internals), avo turbo kit with all the supporting mods. Microtech ECU (i know it's not ideal, but i can't afford to change ecu's)

The car is making 141rwkw on 9psi, but i am getting it retuned as i want a little bit more power and hopefully slightly better fuel economy.

My question is, how much boost would you guys recommend? I was thinking around 14psi (as 15psi seems to be the limit)

Car is mainly a weekend toy, with the occasional 5km trip to work.

Thanks for any info
Steve

[NitroDann]

There is no boost limit.

Boost does not break a stock B series engine. (or any cars engine internals for that matter)

All B6 and BP have the same weak point when boosted, stock rods bend in compression.

This is caused by cylinder pressures, cylinder pressures make torque. So you need to stay clear of a torque figure.

In a stock engine running a T25/28 this figure in HP is 250whp, which is 190wkw.

The other thing that increases cylinder pressure DRASTICALLY is detonation.

So basically, you need to stay below 250whp and DONT DETONATE IT AT ALL.

The detonation warning gets more and more severe the closer you get to the 250whp limit.

If you want to push past 220whp you better be using some form of knock detection be it a high end knock box or detonation headphones and an experienced pair of ears.

How much boost this takes is 110% irrelevant.

If you don't have inconel studs yet, with locking hardware, and if you are not running gasketless between the manifold and the turbo, you are going to have a bad time.

Dann

[totti]

Appreciate the response Dann.

My tuner has asked me what i would like to limit the boost to, so thats why i asked.

Should i simply just tell him to limit the car to 220whp instead, regardless of boost levels?

[NitroDann]

I would tell them that the rods will be fine until 220whp on a sensible tune and 240 if they have the equipment to GUARANTEE it doesnt knock.

But again I stress that at these HP levels you really need inconel and gasketless turbo to manifold connection to be reliable.

Dann

[sailaholic]

Wouldn't the torque produced from X power really be rpm related?

Ie (extreme examples) making 220hp at 1500 rpm and 220 hp at 7000 rpm would have very different torque levels?

Wouldn't it be better then to know what torque figure to keep below rather then power?

[NitroDann]

250ftlb at the wheels, but few dynos read torque correctly because they are never ever calibrated for your diff ratio and rolling diametre, a T28/log on stock cams makes pretty much the same torque at 250whp because of the power delivery of a t28 on stock cams and a log.

Dann

[16bit]

you probably need to take into account the condition of your entire driveline at this level of power.

make sure you have good engine mounts and the gearbox is in good condition.

you make break a 5 speed at 250whp and 250wtq if you drive it harshly.

[totti]

i would be extremely happy with 220-230whp! looks like ill have to have a decent chat with my tuner before she see's the dyno

[NitroDann]

This is the miataturbo wiki.

If you read everything here carefully you are guaranteed to save money and broken parts.

I guarantee it. 110%.

Dann

[totti]

So in theory, the inconel studs and gasketless turbo to manifold connection, are purely to prevent air/boost leak with the extra torque being pumped through the motor? Or do these prevent damage elsewhere?

[NitroDann]

Non inconel studs will stretch and loosen. Inconel is not heat affected like steel is. At 200whp, heat is your new enemy.

The gasket is simply another failure point that needs addressing, the issue with the gasket is that its made to compress, so it allows the vibration of the engine to weaken it as it compresses and the studs loosen.

Long story short if you dont want to deal with tightening all 9 turbo bolts every track day at 200whp+ you have to get the right hardware to bolt it together.

Trust me, you will be forever removing the turbo at the track and fitting new gaskets, or tightening the cheap studs you have, and on an AVO that is a HORRIBLE mission.

Dann

[totti]

Hahaha ok boss i will get the studs!! i better check them on the weekend

[NitroDann]

trackspeed engineering for the 10mm kit if your mechanic wants to drill and tap for 10mm, or flyin miata for the 8mm kit which will bolt right in.

The 8mm will be fine if you arent going to go further with them than this.

Dann

[totti]

do these inconel studs go from the head to manifold, or manifold to turbo? sorry for the stupid question lol

[NitroDann]

manifold to turbo.

Dann