I was kinda hoping you would show the actual car and engine instalation and the takeoff on the exhaust manifold.
Method of installing the takeoff for the pressure reading on the exhaust can skew the readings.

Looking just at the numbers they are really good.

And this is when I cranked the boost up:

Engine RPM 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500

Exh Pres, PSI 3.1 22.4 23.6 24.7 26.0 27.1 28.1 30.2 31.8 32.6 31.4

Boost, PSI 3.0 29.6 29.5 29.4 29.3 29.2 29.2 29.1 29.1 29.0 29.1

Cmprssr Pres Ratio 1.21 3.09 3.09 3.09 3.09 3.09 3.09 3.09 3.09 3.09 3.09

Peak power is at 7500 rpm (round numbers)

And previous, smaller turbo:

Engine RPM 3500 4000 4500 5000 5500 6000 6500 7000 7500

Exh Pres, PSI 10.8 17.0 18.0 18.9 20.6 22.1 23.3 24.5 25.3

Boost, PSI 18.1 24.4 24.4 24.3 24.2 24.1 24.1 24.1 24.0

Cmprssr Pres Ratio 2.24 2.68 2.68 2.68 2.68 2.68 2.68 2.68 2.68

Boost was better a 3500 RPM but max power was a 6500, because the compressor was going 'off map' and becoming very inefficient (and maybe because exhaust back pressure was rising too?). With the bigger turbo I lost 500RPM at the bottom end but gained 1000 RPM at the top end - plus I can run 2 bar boost which the other turbo couldn't manage.

Looks and sounds great, shame you won't show the car off.

You say an 8v too, I thought you were a 16v man

16 valve is the new engine. Progress halted due to the general economic climate!

If it wasn't such a faff getting pictures on here I would put a couple up. You will find some here - though not engine specific:

http://www.flickr.com/photos/34761498@N04/page2/

If you look in the bottom left corner of picture I~000004 you will see a chalk mark on the manifold just before the turbo flange. That is where the pressure sensor now fits. The EGT sensor is fitted 180 degrees opposite this.

^That I can relate to, mines the all time slowest project!

Well I'm impressed, that's a cool car with some nice parts on it.

That's a very cool car.

Thanks

Martin just to confirm,

Your exhaust manifold has some distance between the colector and the turbo and the EMAP point was taken off just before the turbine inlet flange, yes ?

What turbo was fitted during the test readings taken above and were you using a normal 3bar MAP for datalogging it ? Did you need to restrict or dampen the signal line to get such stable readings ?

Ta.

The "small" turbo was a T35 and the "large" turbo is a T38 - both from Turbo Technics.

The manifold is a 4-2-1 and the '1' part is quite a bit longer than just a typical collector length. The manifold/turbine seem to do a fairly good job of dampening out pressure spikes on their own. The sensor take-off is on this pipe about 25mm before the turbo flange.

The sensor was datalogged at 100Hz. On a 4 cylinder engine at 3000 rpm there are exactly 100 exhaust pulses per second and at At 8500 rpm there are 283 per second.

The pressure signal to the sensor is 'damped' by having a small orifice followed by a relatively large volume in the pipework between the manifold and the logging shows a stable output - much the same way as a MAP sensor on a plenum gives a very stable output when logged at the same rate.

Looks like a nice manifold, I always wondered how a 421 might work on a single scroll motor.

Thanks anyway you confirmed an idea I had.