How not to tune your turbo miata

[Woo]

As for the multiplication factor and gearing.

Theoretically, the results should be the same regardless of what gear is used because the increased torque in the lower gears is cancelled by the decreased speeds. In the real world, there are always differences between the gears, and the differences can be explained by a number of factors.Because of nasty things like friction and inertia, different gears always have different amounts of drag, and the greater the reduction or increase in the gearbox, the greater the drag.

A low gear may fly the engine through the rpm range so quickly that it never has a chance to build up any helpful intake and exhaust resonance that those header engineers spend so much time trying to achieve. Fifth gear may be spinning your drivetrain so quickly that significant increases in gearbox drag are created. Third and fourth gears are usually favorites for finding your actual horsepower, and testing all of the gears is a useful method for discovering problems in your drivetrain.

I'm sorry my friend but you have been seriously misled by whomever this quote is by.

Torque = Force * distance (Physics 101)

The distance term describes the distance from the centre of the axle to the outer edge. In a 1:1 ratio system (4th in a 5 spd, 5th in a 6 spd) this distance is the wheel/tyre radius.

Now if you select a lower gear you are effectively applying the same force on a larger radius (how large depends on the gear selected).

Personally, I had AVO dyno my car the week before a Melbourne dyno day and, in 4th gear it pulled 175 kW.

Two days later at the Club day it pulled 139 kW ..... you guessed it, in 5th gear.

Incidently the decrease coincides almost exactly with the 1.258:1 ratio between 4th and 5th.

Two weeks later I had cam gears dialled in by Simon at Nizpro and the pre-adjust pull clocked 141kW, again in 5th.

I would be very suspicious of the author of the quote and any other claims they make imho.

Wòó

[blackster]

I am not going to continue to argue against frivilous tangent off topic points, that ford X did this and my NA done that and that dyno runs should be done in 5th as opposed to 4th.

I am well aware that general tunning principles apply to all boosted applications. The fact of the matter is, this topic pertains to an SE and if you know the car/research as well as you say you do then, why has there been a failure to acknowledge key points:

A. Turbine compressor upgrade with all other mods noted should equate upto 250rwhp on a richer tune with premium pump gas.

B. Leaning that agressively on in the presence of optimal timming does not equate to a huge power increase as featured, but more prone to detonation.

c. That the lean hesitation spike will not show up on any dyno, but if you hook up a wideband 02 or OBDII with real time scanning, you will see very lean AFR at that transition. If you tune say 13.1 at that point with a conventional interceptor that adds pulse width, then this will be overiden by the stock ECU and therefore you will be more lean then noted.

I am done with this topic my aim was to inform others what to look for if considering this path, but more importantly not be fooled by hp numbers that is nor great or safe.

[Sean]

I am not going to continue to argue against frivilous tangent off topic points, that ford X did this and my NA done that and that dyno runs should be done in 5th as opposed to 4th.

You say you are not going to argue anymore then blast out some more points to supposedly support your arguement.

Sorry I was not arguing but debating (big difference) that to suggest a tune is poor based purely on a dyno chart is a pretty tough statement to make, particularly when you dont know the full details, just becuase it was posted on the internet doesn't make it accurate or true.

I am well aware that general tunning principles apply to all boosted applications. The fact of the matter is, this topic pertains to an SE and if you know the car/research as well as you say you do then, why has there been a failure to acknowledge key points:

That's the point exactly - If you are well aware of the principles applying to all (well actually not true but lets assume it's all), why do you continue to take the "This is an SE" line?

How many cars, turbo and non turbo have you tuned, assisted to tune or even sat down and watched in detail while being tuned? Have you personally tested and tuned with the same engine setup on different fuels? I don't want to blow my own trumpet, but I spent a lot of time and effort pulling numbers out of datalogs and testing different things on my car before settling on what i liked best, I don't proclaim to be a guru, but have worked with some of the worlds best and learnt a little from them.

The mention of the article with Simon from Nizpro tunin falcons is extrmely relevant. He used controlled conditions and the most accurate of Dyno's (engine dyno) to demonstrate that you can use a whole bunch of variables indifferent ways to make similar (not exact but similar) power safely.

I would think a tuner (or well researched n00b) would be more interested in seeing why the car was tuned the way it was rather than just coming out and bagging it. If you want to bag a tune, find the guys blowing customer engines repeatedly and start analysing what's going wrong with them - Maybe it's not even a tune issue.

A. Turbine compressor upgrade with all other mods noted should equate upto 250rwhp on a richer tune with premium pump gas.

And your point is? The power is not great, but that could be blamed on any number of factors.

You mention premium pump gas, which excited me a little, does that mean you understand why you can make more power with it? The fuel itself (sorry I dont call it gas cause I'm not a yank) doesn't make any more power, of course we are talking readily available pump petrols, with slightly higher than regular octane, not highly oxygenated race fuels, cause that's even more complex. The higher octane fuel wont make more power by itself, rather it has the effect of increasing the engines resistance to detonation. The result being you can run a little leaner and or more agressive on the boost and timing, resulting in more power.

B. Leaning that agressively on in the presence of optimal timming does not equate to a huge power increase as featured, but more prone to detonation.

Not necessarily more prone to detonation, and "optimal timing" is a variable figure dependant on boost/vac levels and fuel quality, as well as amount of fuel. I dont think anyone was saying that being overly lean was a great thing, nor does the dyno graph suggest it made a huge power increase.

c. That the lean hesitation spike will not show up on any dyno, but if you hook up a wideband 02 or OBDII with real time scanning, you will see very lean AFR at that transition. If you tune say 13.1 at that point with a conventional interceptor that adds pulse width, then this will be overiden by the stock ECU and therefore you will be more lean then noted.

Many dyno's these days have real time logging and playback of a myriad of engine readings for various temps, flows and wideband measured o2. I still dont really see how the dyno misses that?

Anyway, nothing much has come from this topic for anyone involved, so after giving my final opinion I will gracefully bow out of the debate from this point. I dont think anyone will achaive much from the three of us debating it over more and more pages

It's been interesting, but what would I know - I'm just a kid with a keyboard... I dont even own an MX5.

[The Pupat]

As for the multiplication factor and gearing.

Theoretically, the results should be the same regardless of what gear is used because the increased torque in the lower gears is cancelled by the decreased speeds. In the real world, there are always differences between the gears, and the differences can be explained by a number of factors.Because of nasty things like friction and inertia, different gears always have different amounts of drag, and the greater the reduction or increase in the gearbox, the greater the drag.

A low gear may fly the engine through the rpm range so quickly that it never has a chance to build up any helpful intake and exhaust resonance that those header engineers spend so much time trying to achieve. Fifth gear may be spinning your drivetrain so quickly that significant increases in gearbox drag are created. Third and fourth gears are usually favorites for finding your actual horsepower, and testing all of the gears is a useful method for discovering problems in your drivetrain.

I'm sorry my friend but you have been seriously misled by whomever this quote is by.

Torque = Force * distance (Physics 101)

The distance term describes the distance from the centre of the axle to the outer edge. In a 1:1 ratio system (4th in a 5 spd, 5th in a 6 spd) this distance is the wheel/tyre radius.

Now if you select a lower gear you are effectively applying the same force on a larger radius (how large depends on the gear selected).

Personally, I had AVO dyno my car the week before a Melbourne dyno day and, in 4th gear it pulled 175 kW.

Two days later at the Club day it pulled 139 kW ..... you guessed it, in 5th gear.

Incidently the decrease coincides almost exactly with the 1.258:1 ratio between 4th and 5th.

Two weeks later I had cam gears dialled in by Simon at Nizpro and the pre-adjust pull clocked 141kW, again in 5th.

I would be very suspicious of the author of the quote and any other claims they make imho.

Wòó

A: he was correct, you are wrong. The only line worth looking at on a chassis dyno is the power line as it's the only one remotely accurate, the torque line is good to get an idea of how the motor is making torque but useless on gauging actual quantities produced.

B: Sounds like avo need to spend a bit of time learning to use a dyno. This is part of the reason why with a turbo car you have build boost in the system before hitting it. Chasis Dynos aren't as accurate as engine dyno and use a few "tricks" to accurately measure power. If you don't use the correct and with the tricks it won't give you an accurate result.

[Woo]

Thanks Pupat, I'll let my Physics Professors know that what they spent years trying to get through my thick head was crap.

Generally I would call for a reference to unsupported claims, but I already see that the Google button is beyond the reach of some people.

Try Wiki

Wòó

[The Pupat]

Thanks Pupat, I'll let my Physics Professors know that what they spent years trying to get through my thick head was crap.

Generally I would call for a reference to unsupported claims, but I already see that the Google button is beyond the reach of some people.

Try Wiki

Wòó

If I got it wrong my old university better come and take back their degree.

Yes I know all about torque multiplication. But the simple factor is a motor produces a set amount of power full stop. Power is a measure of energy x time or in car terms torque x speed. Rule 1 in Physic is energy can't be created nor destroyed so extrapolating that out, Power can neither be created nor destroyed. So an engine makes a set amount of power always for a given set of parameters. This power is then transmitted (with some loss to other systems but never destoryed) to the tyres. So given this fact you can work out that power is constant therefore if you increase torque you must also proportionately decrease speed and of course the opposite is also true. Therefore theoretically what gear you dyno a car in doesn't matter since the calculation is based on both force transmitted to the roller as well as roller speed. Now the only thing in the system that can change is how much you lose to it through gear contact and tyres etc which can effect how much power you see as each individual gearset will have a different loss.... but it will be in the magnitude of <5% by a long margin.

The real reason as stated is that most dyno have a speed limit that is not supposed to be exceeded as well as a torque rating I'd imagine. So you run it at as high a speed as possible without exceeding the speed limit (I thought dynodynamics was around the 200km/hr).

Still sure you interpreted what the physics professors stated is correct.

[Woo]

In principle I would agree with what you're saying Pupat. Your physics is correct but your mechanical knowledge sucks.

Your claim is based on a false premise when applied to dynamometers.

Dynos measure torque and RPM not Power and RPM.

From this torque measurement Power is calculated (considering gearing).

(Source: Wiki http://en.wikipedia.org/wiki/Dynamometer)

My PhD was worthwhile after all

Oh, and btw, the two Dynodynamics I regularly use are rated at 300 kph.

[Boags]

OMFG!!! TEH FORUMS R PHUXORRED!!!!111

Very interesting reading guys, I'm learning lots.

Boags

[Sean]

OMFG!!! TEH FORUMS R PHUXORRED!!!!111

Very interesting reading guys, I'm learning lots.

Boags

Mate, can you organise us a group buy?

Chill Pills by the box methinks...

[The Pupat]

In principle I would agree with what you're saying Pupat. Your physics is correct but your mechanical knowledge sucks.

Your claim is based on a false premise when applied to dynamometers.

Dynos measure torque and RPM not Power and RPM.

From this torque measurement Power is calculated (considering gearing).

(Source: Wiki http://en.wikipedia.org/wiki/Dynamometer)

My PhD was worthwhile after all

Oh, and btw, the two Dynodynamics I regularly use are rated at 300 kph.

Okay then what's wrong with my mechanical knowledge? Ohhh you do also know that 1:1 gear on a car is 1:1 on the gearbox only there is still a 4odd : 1 reduction in diff.

[AJ]

geez, i'm starting to gag on all teh popcorn i've eaten