Porsche turbo boost reference timing retard

[Holden202T]

jayme might have some input on that subject, he's delcod a air cooled motorbike motor.

[vlad01]

Porsche are bit on the extreme side of aircooled engines. I do believe they run something like 10-11:1 CR on NA and around 9 something for turbo.

fans output is around 3200 cfm just to cool the heads and cylinders. I know they normally run them richer than water cooled engine to help keep head temps in check as they do fluctuate temps wildly compared to water cooled as water has very big heat capacity, stores and releases vast amounts of heat and that helps keeps temps stable. Tuned them wrong and you can cook the heads and pistons with no signs. So you must monitor them while tuning. EGT would be helpful too.

They also have dry sump system with massive oil storage. something like 12L iirc and run 2 big 1/2" lines to the front for the oil cooler. Thats because they are pretty high revving engines designed to be flogged continuously thus it heats the oil a lot.

these are what typical heads and jugs look like.

[Jayme]

haha my motorbike engine never made it off the shed floor.... I was using a water temp sensor jammed in between the head fins to read the head temp... had it up to 130 deg on the shed floor before I realised I should turn the fan on

[vlad01]

I think we might have to use a different sensor than the stock? does the code support more than 150 coz we could see temps higher than that in normal operation.

[kojab]

We used the sump oil temperature as a substitute for coolant temp on this 911.

http://www.tunersgroup.com/supercharged_911.html

Originally the 911 had mechanical injection, now uses VR manual ECM.

It was real challenge to tune this combination over several race seasons.

Ray Fowler the owner was a very nice man to work with. His son Richard is a great driver too.

[vlad01]

oh yeah oil temps would be more like a water cooled setup temps. a lot more stable that AC heads. which range from 120 to about 175 for healthy rage.

oil would be somewhere around 60-90 c.

only prob is oil and head temps are very separate and dont reflect each other. head is load related, oil is rpm related. Perhaps the crank case at the cylinder base would be better?

[Jayme]

Yeah youd def need a different sensor. The vn coolant sensor peggs at 135ish and sets a coolant temp volts high dtc lol. Youd have to use a sensor that reads high enough and maybe fudge the readings and tables to keep the ecu thinking in 30-100 range

[vlad01]

yeah give it some no linearity at the top end.

[Gareth]

PM'd VL400


Fitting an Eboost to the porka tomorrow, that will help with tuneability seems to have been a great car that was built a long time ago, it is becoming obvious how far tuning technology has come. The current boost control is just a tap...literally... So if you want more, turn it up, only trouble is you don't know what you're going to get until you've got it. 'Woops, too much, bang', too easy

[Holden202T]

tap as in to regulate boost/vacuum to the gate ?