Boost,boost,boost...........

[xr6tblueprint]

I suppose we would all be stupid if we drove "normally " anywhere, after all that's why you buy a turbo- to get there quicker!

[Buf-Phoon]

I make 300rwkw on 12psi.

Good ol unichip

<{POST_SNAPBACK}>

Really, dont know what other mods you have but ....... tick tick tick

<{POST_SNAPBACK}>

About the same as you.

<{POST_SNAPBACK}>

ummm fair enough , you are an auto right.Only 12 PSI for 300 at the treads .

My T with same mods only made 280 rwkw and it was pretty much at the limit at that boost level. I assume that FIST did your work so all should be safe

Should have read closer I guess Don't want to start any

[gogo]

It should also be mentioned that power will not necessarily be proportional to boost.

There are also other limitations - most of which have been touched on already such as fuel, timing, and physical capacity of the turbo. Other factors will also impact maximum power such as loses through both inlet and exhaust, inlet temperature and rpm at which peak power is made to name a few.

I know for many this is teaching you to suck eggs, but for those that might not understand...

Fundamentally power is made by burning fuel to increase the pressure in the cylinder. This pressure acts on the piston to push it down during the power/combustion stroke. This is the basis of how the engine works.

In order for the fuel to combust properly, you also need to have sufficient oxygen (air) to burn the fuel. Hence you cannot just stick in more fuel (rich mixture).

As you all no doubt know, a turbo increases the pressure of the air being feed to the engine to increase it's density = more air = you can combust more fuel so should acheive higher pressures in the cylinders = more work done by the engine = more power

However it the mass (which is proportional to density) of oxygen that you can push into the cylinder that is truely important. The density of the charge is proportional to two things - the pressure and the temperature.

The turbo does two things - it increases the pressure but as it does so it also increases its temperature.

Enter the intercooler, the job of which is to cool to the air before it enters the cylinder. Car with a cooler inlet charge should be capable of producing more power than the same car with a higher inlet charge temperature. Hence more power on cool nights, or more sustained power for the car with the more effictive cooler.

Ignition timing and valve time - particularly on BF's and the typhoons which have the full variable valve timing also play a significant part. This is where the custom tune comes in.

In general, valve timing can be 'tweaked' to provide the optimum flow of air and fuel charge into the cylinder, and spent gas out of the cylinder - this can improve the effency of 'pumping' the gases and also maximise the mass and minimise temperature of the fresh charge, whilst reducing the amount of unspend fuel being discharged to exhaust. Optimum timing of valve operation should improve engine efficiency through lower losses, resulting in an increase in net power, fuel efficiency and it is also very important for controlling emissions.

Ignition time is critical for both power and also safe engine operation. Within reason a car will generally produce more power the earlier in the compression stroke the charge is ignited. I say within reason. Whilst ignition in advance of the end of the compression stroke increases the pressure on the piston as it comes up(which we don't want), the additional net pressure on our power stroke more than compensates for this. This because in a spark ignition engine we want the fuel to burn progressively. This starts with the spark at the spark plug and propogates through the cylinder. Because the flame front start at a point and spreads, in the first part of the burning process little fuel is burnt (small flame area), but as the flame spreads, the front gets bigger and bigger increasing the rate at which fuel is consumed and pressure increases. Modern cars charge the amount of timing to try and acheive optimum efficincy at different engine speeds because the burning process takes about the same amount of time regardless of how far the piston is moving.

The issue with advancing timing too far is that this increases both the temperature and pressure of the unburnt charge ahead of the flame, and if this gets too high the charge will 'explode' resulting in knock which can damage the engine.

Once the fuel has done it's job and combusted, pushing down the piston, the engine gets rid of it in preparation of the next cycle, and the spent mix and remaining unburnt fuel are exhausted and pass through the turbo. The less back pressure on the turbo (from a free flowing exhaust) the easier it is to exhaust the gases from the engine whist providing the input energy to the turbo, so the lower the losses = a little more power.

Similarly on the inlet side, the freer the flow of air, the less energy is needed to be consumed by the turbo to acheive a given pressure at inlet (which helps with power) as distinct from boost at the turbo. This also means that for the same boost levels at the turbo the car should acheive a higher inlet pressure, which all other things being equal should provide the capacity to combust more fuel and produce more power.

Finally, the turbo itself is limited in just how much air it can compress (hence beasts like bcl's have larger turbos). This with the other restriction will determine the maximum air flow the car can physically support. The more restrictive, the lower the capability to support high inlet pressures at low temperature at high rpm. It is this mix with the 'right' timings that will yeild high power figures...

If anyone is still reading - well done.

I think that is enough of an essay for one night!

Cheers

Ben.

[gogo]

from memory,

331rwkw @ 14psi - (peak boost 15.5psi at 3200rpm) on 98 octane fuel

309rwkw @ 14psi - on 95 octane - I understand has about 4 degree's taken out

cheers,

Ben.

[silverman]

As far as fuel goes my car with 192rwkw ran 10.3ltrs/100kms then with edit,custom tune etc and 297rwkw ran 9.2ltrs/100kms- highway kms that is !!

Now with the extra oomph you are only using part throttle around town which is more economical.Put the boot in however and its a different story.

So if I took the mods a step further and put a nizpro stage 2 to get 330rwkw(currently has nizpro stage 1 running 297rwkw @13psi)I wonder how much more boost will it run and if you would notice 30rwkw extra with 3psi more.

[Adam]

I wouldn't bother Silverman.

Don't get me wrong the Nizpro Stage II kit is top gear but with stock internals they will only tune it to 320rwkw's. That's a lot of dough for just 20-30rwkw's more.

I'd stick with what you have currently.

[gogo]

As far as fuel goes my car with 192rwkw ran 10.3ltrs/100kms then with edit,custom tune etc and 297rwkw ran 9.2ltrs/100kms- highway kms that is !!

Now with the extra oomph you are only using part throttle around town which is more economical.Put the boot in however and its a different story.

So if I took the mods a step further and put a nizpro stage 2 to get 330rwkw(currently has nizpro stage 1 running 297rwkw @13psi)I wonder  how much more boost will it run and if you would notice 30rwkw extra with 3psi more.

<{POST_SNAPBACK}>

Nizpro would be able to tell you more...

I am running about 14psi for my 330, but probably at higher rpm.

My mid range torque with the Nizpro stage 2 is identical to what I had previously when running similar power levels to you (this was to preserve engine internals). The key differences are more top end, and much better drivability and response.

See if Simon can organise a drive for you - I am happy to take you for a spin.

cheers,

Ben.

[gogo]

I wouldn't bother Silverman.

Don't get me wrong the Nizpro Stage II kit is top gear but with stock internals they will only tune it to 320rwkw's. That's a lot of dough for just 20-30rwkw's more.

I'd stick with what you have currently.

<{POST_SNAPBACK}>

Agree Adam, lots of dollars for not much more power, but in my case it transformed the car from a drivability sense. Having said that I have not been in a stage 1 nizpro car, so not sure what their tunes are like at the 300rwkw level.

Cheers,

Ben.

[silverman]

Yeah that's probably right Adam. Bang for buck isnt brilliant,though it is tempting.Wonder what else I could do to get to 330rwkw. Um....

[Adam]

Put rods and pistons in the girl and then unleash the Stage II kit.