Date:         Thu, 31 Aug 2000 21:29:25 -0500
Reply-To:     John Rodgers <inua@HIWAAY.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Rodgers <inua@HIWAAY.NET>
Subject:      Re: engine temps sightly OT, was Fiberglass Taped Exhaust
Comments: To: Alistair Bell <albell@UVIC.CA>
Content-Type: text/plain; charset=us-ascii

Interesting commentary about the temp sensor providing data so the ECU can
direct a backoff on turbo boost pressure when it gets to hot.

Distantly related only by the science of it, is the fact that jet aircraft
engines operate similarly , in that pilots have to keep an eye on two  things to
protect the engines and get best performance. EPR - Exhaust Pressure Ratio. TIT
- Turbine Inlet  Temperature. On a cold day like in Alaska in winter, pilots
really have to keep an eye out because the cold air being injested can result in
an EPR that reflects an overpower/over torque condition and can destroy the
engine. On the other hand, really hot TIT on takeoff on a hot day at high
altitude- produces a poor EPR which means low relative power. Then it requires a
take off run of miles to ever get off the ground. It may also require the load
in the aircraft be limited as well. All of that has to be calculated for every
flight made to ensure that the load and the power available and the lift that
can be generated can get the airplane safely into flight.

Just my two cents.

John Rodgers
Birmingham, AL

Alistair Bell wrote:

> This talk about exhuast and by extension engine compartment temps reminds me
> of an article i just read in Road and Track (comparing Boxster S, Z3, Honda
> 2000, Audi TT).
>
> It seems that the TT has a temp sensor connected to the ECU that measures
> engine temp and allows the ECU to back off turbo boost pressure wehn the
> temp gets too high.
>
> Maybe useful info for those inclined to install the 1.8 turbo in a van -
> single or biturbo ;)
>
> Alistair