Winter Work on Lisa

Posted: December 6, 2010 in Racing

Now with Lisa living in a proper garage with skilled mechanics she can get some much needed work completed over the winter.  But before a little background from last summer’s racing and exploits.

Engine Failure

Earlier this year I suffered from my first ever engine failure (well…in a race car).  In Race two at Autobahn in July 2010 I was fighting for 3rd place with Michael Palmer and on lap 8 in Turn 6 the stock oil pressure light went on and I checked the oil pressure gauge and it read less than 1 bar (~ 20 psi) during acceleration (i.e bad as it should be above 60 psi).  I quickly got off the gas and idled the rest of the way around the track into the pit area where I shut it off.  Car was not leaking any oil or didn’t have the tell-tale bad knocking sound but there was something knocking.  I put the car back on the trailer after the race was over only to find out my oil pickup tube broke and starved the engine of oil.  It chewed up two rod bearings and unfortunately also scored the journals on the crank.  With tolerances and high rpms these engines make – it required a complete engine rebuild as rod bearing shavings cycled their way through the engine and the crank was useless (not even for turning the journals and running oversized bearings which are no longer made).

Search for a New Engine and Unexpected Benefit

This led me to the need for another engine.  I searched for several days for used engines on Craigslist, forums and salvage yards that were with/in a days drive.  I lucked across a local ’87 924S for sale that was Maaco’d a magenta / pink color (turning off a great majority of people looking for a drivers car and limiting its sale to Avon representatives and those looking for parts cars).  I came and took a look at it and the engine ran great and the price was right.  I wound up getting the car the same price as I would have to have paid for a used engine – so I couldn’t go wrong with that.  Drove it home that night and even took my son to soccer practice one day for the hell of it.  Well I found out later that I was lucky I didn’t break the timing belt as it had lots of stress / age cracks on it.  A snapped belt would lead to the failure of the timing of the pistons in the engine block and the valves in the cylinder head (944 engine is an interference engine meaning that the valves actually will open far enough to go down into the cylinder’s themselves when the piston would be down in its stroke – if that timing fails then there’s a good chance the piston will hit a valve meaning – new engine.

I invited my friend Karl over to check out the engine (run compression test) and look it over.  He also rebuilt the 924S engine and we also installed a new set of fuel lines in the engine bay.  Karl runs his own blog and here’s a link to that article.  Part 1 – engine teardown showing wear on timing beltPart 2 – Reseal continued.

Well it turns out the compression was good and even better the car had the rare factory option LSD transmission (7Q) and even better it also had the short 5th gear (meaning better acceleration in top gear as some tracks we race at we have to use 5th gear – but less mpg in a street car).  All told the transmission itself is worth much more than what I paid for the car.  Totally happy as this was something I needed to eventually do as adding an LSD transmission helps not only with acceleration but also with braking is it helps stop lock up in the rear wheels (our cars do not have anti-lock braking systems [ABS]).  For more information on how differentials in a transmission work (whether open or LSD – check out this link from HowStuffWorks).

List of Winter Work to Be Done to Lisa

  • Replace the entire dashboard with new mechanical gauges (more reliable than the stock VDO Porsche gauges)
  • Remove 30lbs of unnecessary wiring and relays under the dash and in the engine wiring harness
  • Install a blower motor and ducting to run air in from the outside to the driver and windshield (prevents fog on humid / wet days).
  • Swap out early open differential transmission with limited slip differential (LSD) transmission (replace the 2nd gear synchro as it was damaged).  BENMS tested the LSD and it is in great shape (sometimes the stock LSDs have too much miles or are so badly worn that they need to be rebuilt which costs the same as getting an LSD transmission.
  • Fix tie rod play and replace boot.
  • Replace all stock bushings with Delrin (Delrin is a harder compound and takes out flex in the rubber bushings giving you more feel at the expense of allowing more vibration).
  • Remove muffler and weld in pipe to free up a little more HP
  • Replace throttle cable and throttle pedal
  • Replace and reroute fuel vapor lines as they leak fuel vapor into interior (not the best smell to have in the back of your mind when driving a hot race car)
  • Replace my current i/o port seat back brace (bolt on) with welded in unit that will not pivot upon rear end crash.  Story behind this that a bolt on back seat brace can pivot and allow the seat to move backwards which is bad in a crash.  Earlier this year this problem happened when a 944S2 E class PCA car crashed in turn 9 at HPT (went backwards into the wall) and the driver had a pivot point seat back back which failed to hold the seat securely.
  • Replace tow hooks with ones that will not stick out from the bumpers, thus protecting everyones’ shins from painful knocks and damage other cars’ rear bumpers when doing bump drafting.
  • Swap in Hawk blue rear brake pads in order to give me a better brake balance.  I was running Hawk DTC 70’s in the front and DTC 60’s in the rear and I found with my open transmission I was too easily locking up the rear brakes in trail braking forcing me to brake more before the turn bleeding off speed.
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