3S-GTE Engine Trivia

From: uunet!sitka.triumf.ca!solu@uunet.uu.net (Richard Soluk)
Subject: interesting features of the MkII turbo engine
To: uunet!validgh.com!mr2-interest@uunet.uu.net
Date: Wed, 26 Apr 1995 17:09:56 -0700 (PDT)


  This is trivia for owners of MkII turboes (sp?) who might be
interested in some of the features in their engine.  After about
65000 km I had the engine of my '91 dismantled.  To be honest there
were a couple of minor factory defects.  One of which, a small flake
of metal impacted onto one of the cam bearings, was interfering with
oil flow and might eventually have led to camshaft failure (after a
lot more mileage).  But over all I was very impressed with the 3SGT
engine.

  - there appears to be a small oil-to-water oil cooler at the base of
    the oil filter
  - there is a butterfly valve on the intake manifold which restricts
    air to a single valve per cylinder at low RPM thus improving low
    end torque
  - there are oil jets to cool the pistons
  - the camshafts act directly on the valves, there are no rocker arms
    to fail or add to the moving mass of the engine
  - it has slotted main bearings for better oil flow and I'm told
    a very heavy duty forged crankshaft
  - the cylinders are about as large as possible for this block with
    only 7mm of cast iron between them (the normally aspirated version
    has a 1mm larger bore)
  - the castings on the intake/exhaust manifolds and head are much
    smoother then most Japanese or US cars, Extrudehone Corp. told me
    there would be only minimal benefit from extrusion honing them
  - I had someone spend a lot of time (or rather a lot of my $'s)
    doing work on the head and he only achieved about a 5% increase in
    flow, he tells me the head flows almost as much volume as a 350cid
    small block V8
  - on a lot of cars the exhaust manifold will crack (aftermarket
    performance manifolds are especially prone to this), however the
    MR2 seems to use a very hard high nickel content steel, the shop I had
    polishing it wore through several grinding stones, they had never
    seen one this tough before
  - JG Engine Dynamics has told me that to run very high boost the
    connecting rods should be shock peened to remove internal stresses
    but don't need to be replaced (of course they also said the cast
    Al pistons can melt, but hey, nothings perfect)
  - I've also been told the transmission will handle high horsepower
    but the clutch can't.  Currently TRD is the only source for new
    clutches but Centerforce will be introducing a dual-friction
    clutch later this summer.
  - as you probably know from your HKS catalogs, this is the only car
    you can get a fuel cut defenser for without getting a PFC F-con,
    in fact looking at their full set of upgrades (beyond what they
    put in their catalog) they run this car up to 318hp without
    changing the fuel computer (other then adding a VPC)!

Toyota really did an excellent job designing this engine.  Its a shame they
didn't bother telling anyone or they might have been able to sell more
of these cars (Mazda and Honda make a point of mentioning engineering
features).

   ...Richard
   solu@sitka.triumf.ca