Limited Duration Extra Turbo Boost

[Andy Whittaker - Chester UK]

Yep,

This is a Lotus favourite. On the Lotus Esprit you rev the engine above
5000rpm while the car is stationary. You then get about 27 seconds of
overboost. How it works is quite complicated, it appears to knobble the duty
cycle calculation. However, there is a MAP table where the target boost is
looked up per band of RPM, I guess that would be a better place to modify.

P.S. The normal "controlled" boost on my Esprit GT3 is 0.97bar with an
uncontrolled boost of around 0.5bar.

Andy.
------------------------------------------
Andy Whittaker
Chester, England.
Email: mail at andywhittaker.com
Web: http://www.andywhittaker.com/
ECU Stuff: http://www.andywhittaker.com/ecu/


----- Original Message -----
From: "Malcolm Robb, LC 0112G" <Webmaster at lotus-carlton.fsnet.co.uk>
To: <gmecm at diy-efi.org>
Sent: Thursday, July 13, 2000 6:29 PM
Subject: Limited Duration Extra Turbo Boost


> I have received a little extra information about the turbo boost behaviour
> in my car (Lotus Carlton, or LC for short, 1228831 P4 ECU) from a usually
> relyable source. He claims that the LC emissions were not clean enough to
> pass the normal requirements of the Swiss authorities back in 1990. But at
> that time, there was an exemption for so called 'super cars' which ment
> that things like Ferrari's, Porche's, Lamborghinis etc, didn't have to
pass
> such strict requirements. To qualify as a 'super car', the manufacturer
had
> to proove that the car could beat certain 0-60MPH and 0-100MPH times.
>
> (P4 EFI content coming up chaps !)
>
> To meet these acceleration times, Lotus are supposed to have added a 15
(or
> 25) second duration extra boost capability, possibly implemented through
> the waste gate solenoid duty cycle. Does anybody know anything about this
> type of code in the Turbo P4 ECU ? Is it possible to extend this time
> indefinatly (head gasket and temperatures permitting ) ? The normal wast
> egate opening pressure is 1.55BAR (8 PSI boost) and the engine has a 2 Bar
> MAP sensor, so it could/should be possible to get to (say) 1.9 bar (13+
psi
> boost) by varying the solenoid duty cycle, and still keep the MAP sensor
> within range.
>
> I've read TurboP4.pdf a couple of times, and can't see anything in there
> about it.
>
> I know it's a long shot, the '8831 being so rare, but I thought someone
> might know something,.
>
> Cheers,
> Malcolm Robb, LC 0112G
>
>
> --------------------------------------------------------------------------
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