GTR Forum banner

101 - 113 of 113 Posts

·
Registered
Joined
·
1,166 Posts
If you pass a given mass flow of gas down a pipe at pressure, it comes out the end of the pipe at a lower pressure than it went in at. This is due to boundary layer friction effect and turbulence in the flow.

For the same mass flow and pressure, increasing pipe diameter decreases the pressure loss. Reducing the acuteness of bends and improving the bend radius to pipe diameter relationship all help pressure drop.

This is why you use larger pipes with higher mass flows and pressures. This is why a lower loss air filter makes more power. This is why larger throttle bodies are used, its why the Nismo high pressure pipework is soooooo nice, its why the GTR shop baffled twin-turbo pipe should make more power etc etc etc

The compressor is pulling air through the air filters, MAFS, low pressure pipe work etc etc. This results in an intake depression infront of compressor (Negative pressure). The compressor then does work on the gas to increase its pressure (and temp). This high pressure gas is then transported down the high pressure pipework, through the I/C where it is cooled (some additional pressure loss due to the cooling effect), through the throttle plate and into the manifold, then through throttle bodies, past valves into combustion chamber.

So, in your example where you are running the turbo at 1.6bar boost:

Pressure in intake manifold: 1.6bar
Pressure at hot side of I/C: ~ 1.8bar
Pressure at compressor outlet: ~1.9bar
Intake depression at compressor inlet: ~ -0.3bar

Therfore inorder to run 1.6bar at the intake manifold, you are actually running the compressor / turbine assembly at 2.2bar. Not good.

Don`t forget; higher compressor work requires more energy to be supplied from the turbine. More energy from turbine is higher pre-turbine pressure which results in lower volumetric effeciency across the head, more trapped residual, more intake charge heating and a lower knock threshold.
 

·
Registered
Joined
·
1,350 Posts
Hi Adam.
Maybe your std rubber intake hoses are deforming a bit at the top end and disturbing the airflow at the inlet ?
Just a thought.
cokey
 

·
Registered
Joined
·
4,821 Posts
Discussion Starter #104
yup....

I think there are several factors.... the turbos are sucking through soggy teabags (old dirty filters) - then pushing the air through an old crapy IC via some rubber IC pipes. (I know that the psgr side rubber IC pipe has its outer cover removed too)
 

·
Registered
Joined
·
2,750 Posts
defintely get some jubilee clips round that pipe...and the other side.

Youve got me thinking that i really should change all my intake pipework to metal now...
 

·
Registered
Joined
·
4,429 Posts
Take the air filter off completely next time you dyno it,
I had trouble with mine a long time ago, took the filters off and got like 40 hp .....went round to soichi's and got 2 new apexi ones.
Definately was holding it back
 

·
Registered
Joined
·
2,750 Posts
Take the air filter off completely next time you dyno it,
I had trouble with mine a long time ago, took the filters off and got like 40 hp .....went round to soichi's and got 2 new apexi ones.
Definately was holding it back
think i said to try that earlier on, its definitely worth a go....given that you can on a d-jetro...
 

·
Registered
Joined
·
4,821 Posts
Discussion Starter #113
:S there wasnt anything wrong with the fueling.

We are now running a 2l surge tank, with dual Bosch pumps (Tomei pickup pump) to a twin entry rail (-6 braided lines) and 800cc Injectors.

Also have a HEL fuel sampling kit in line now too.
 
101 - 113 of 113 Posts
Top