Air Box, what's that all about?

[_Nathan_]

You've got me wondering about messing about with trumpet lengths on the dyno now just to see how it messes with the curve.

[alexk]

Originally Posted by _Nathan_

You've got me wondering about messing about with trumpet lengths on the dyno now just to see how it messes with the curve.

You will love it
Make sure you observe the acceleration time (i.e. from 2k rpm to 8k rpm) before and after.
I have seen once that the HP/torque was the same but there was a difference of 1 sec (bikes again).

Tomorrow I will get my paper from the CSL with the measurements of intake air temperature.

[The Gorilla]

Hi,

AlexK- No, I have not come across
aftermarket longer Intake Trumpets for
the S50 engines.

Its the curve and shape of the std ones that is
the clever bit, and how they cycle
the air velocity from the plenum.

Extending the std ones would be quite
simple so that a 'sliding' extension could
be moved up or down at the TB end, to monitor the
changes.

Not sure at what stage the air volume in
plenum would then need to be addressed.

I did at one stage look at going with a set
of Slides for the S54.

Scheel make them and they also make them for
the BMW S38 Engine [M5 L6] so port spacings
for the 6 pot is not a problem.

Bit misleading of Peter Meyer to say that its a
20 BHP + plus gain on the slides over TB's.

49.5mm V 48mm, like to see with 50mm TB's !!

www.scheel.ch

Slides are only really for use on Race engines
as the mid rev Band tends to create a mid
band gap, due to the design of a circle passing
over a circle.

Its not a progressive take up like a TB Butterfly.

Surprised that nobody Racing, fitted Slides to the
S54 though, more so with very high lift Cams.

Regards,

The Gorilla.

[alexk]

Hi Gorilla,

Interesting information as always
Scheel is relatively close to me, I might go to the meet them at some point.

So back to the subject of the intake.
Some information I gathered in autumn of 2010, when doing a drive to Stuttgart in Germany.

The atmospheric temperature was 10 degrees.
I don't remember what is the metric for the mass of air (possibly litres per second, but I can be wrong).
Sport is on and the flap was open in all cases.

Speed | Intake temperature (C) | Mass
--------------------------------------------
60km/h 23 C n/a
150km/h 14 C 27
260km/h 6 C 44

The massive difference of the intake temperature is clear, as well as the mass (150 and 260 were with same rpm as I recall with 4th and 6th gear).

I could repeat the tests soon (I am pending a trip to Munich and Salzburg ) and get more sophisticated measurements with my updated telemetry.
I will update you in 2-3 weeks time with new values.

[karbonkid]

Originally Posted by alexk

Hi Gorilla,

Interesting information as always
Scheel is relatively close to me, I might go to the meet them at some point.

So back to the subject of the intake.
Some information I gathered in autumn of 2010, when doing a drive to Stuttgart in Germany.

The atmospheric temperature was 10 degrees.
I don't remember what is the metric for the mass of air (possibly litres per second, but I can be wrong).
Sport is on and the flap was open in all cases.

Speed | Intake temperature (C) | Mass
--------------------------------------------
60km/h 23 C n/a
150km/h 14 C 27
260km/h 6 C 44

The massive difference of the intake temperature is clear, as well as the mass (150 and 260 were with same rpm as I recall with 4th and 6th gear).

I could repeat the tests soon (I am pending a trip to Munich and Salzburg ) and get more sophisticated measurements with my updated telemetry.
I will update you in 2-3 weeks time with new values.

Any update on this?

[alexk]

Originally Posted by karbonkid

Any update on this?

Sorry Alex, I forgot about it.
I will revisit it and let you know.

[sfh3l]

Alex,
Your figures are indeed interesting. My Cecil is long gone now but I still maintain a keen interest
What interests me here is the drop in air temp. Are we saying that the intake is designed not only to get the 'ram' effect, but also that once the air is in, there is some sort of pressure drop into the plenum as the car goes faster - thus lowering the charge temp? Now that really would be clever.

[Mike R]

True ram-air systems pressurise the plenum, which actually gives a supercharging effect. However, it is such a small amount (even the best systems only manage a few psi), that the only way to check this is by either interrogating the MAP sensor (if it has one) live on the road (no rolling road outside of F1 could replicate the ram air effect) or by fitting an accurate pressure sensor in the plenum that has peak memory recall (something like a digital SPA gauge). Just measuring the air flow and intake temperature won't reveal if there is any "ram air" actually taking place and unless there is some form of heat exchange process going on inside the plenum, you'll never achieve better than ambient either any way .

[alexk]

Do you by now know what the CSL has (MAF or MAP) ?

[Mike R]

Originally Posted by alexk

Do you by now know what the CSL has (MAF or MAP) ?

I was speaking in general about checking out the effects of ram air on any vehicle that claims to operate such a system . I know the CSL runs a MAP sensor, that was clearly listed in the info you provided early in the week . Some systems (like the Ford EECIV) on the 1994 onwards Escort Cosworth run a system that uses both a MAF and a MAP sensor and some systems just use throttle positional based mapping.