Toyota
7M-GE Engine Details by 7MGTE
Just
some trivial info on the Supra engines for those interested.
7M-GE
The Toyota 7M-GE introduced in the early months of 1986 is a 3.0
litre (2954 cc) 24-valve (4 valves per cylinder) DOHC/fuel injected
engine. The valves are spaced at a performance-oriented 50°
angle. Cylinder bore is 83 mm (3.27 in) and stroke is 91 mm (3.58
in).
The
7M-GE was produced from 1986 through 1992. Output was 190-204 hp
(142-152 kW) at 6000 rpm and 185-196 ft·lbf (250-265 Nm)
at 4800 rpm.
Notwithstanding
the technical sophistication and powerful output of the engine,
it was plagued with the problem of regularly blowing head gaskets.
This was because the head gasket was originally meant to be made
out of asbestos; at the last second they changed the material--but
not the 56 ft·lbf torque spec. The turbo version 7M-GTE suffered
from the same problem. Permanent fixes typically involved a metal
after-market headgasket, higher torque settings (usually 70-80 ft·lbf)
and upgrading to head studs (through the ubiquitous ARP and their
hardware) rather than bolts.
Specifications:
Displacement:
2954 cc (180.2 cu in)
Bore: 83.00 mm (3.27 in)
Stroke: 91.00 mm (3.58 in)
Compression Ratio: 9.1:1
Weight: 119.5 kg (440 lb)
Applications:
1986.5–1992
(1987–1993 in Japan) Toyota Supra MkIII (MA70)
1988–1993 Toyota Soarer
1989–1992 Toyota Cressida Mark II (MX83)
Toyota Chaser
Toyota Crown
7M-GTE
The turbocharged 7M-GTE was Toyota's top performance engine from
1987 through 1992. Output was 232 hp (173 kW) at 5600 rpm and 240
ft·lbf (325 Nm) at 4000 rpm for most 5 lbf/in²/0.35
bar versions.
A
special 7M-GTEu version, with a modified CT26 high-flow turbocharger
and large volume intercooler, pushed output to 267 hp (199.1 kW)
at 5600 rpm and 264 ft·lbf (357 Nm) at 4400 rpm. This was
used only in the racing homologation Toyota Supra Turbo A road and
race cars. The Turbo A models also measured air based on manifold
pressure rather than using an air flow meter, had a larger intercooler,
larger throttle body, optimized CT-26 turbo, and various other differences.
In fact, for the short time it was produced, it was the fastest
Japanese car ever made.
Specifications:
Displacement:
2954 cc (180.2 cu in)
Bore: 83.00 mm (3.27 in)
Stroke: 91.00 mm (3.58 in)
Compression Ratio: 8.4:1
Weight: 119.5 kg (440 lb)
Applications:
1986.5–1992
Toyota Supra MkIII (MA71)
1988–1993 Toyota Soarer
The 7 Series M engine was the last of the M blocks. The evolution
from a 2000cc SOHC in-line 6 cylinder to a 3000cc DOHC 24 valve
saw this engine family powering Toyota’s top of the line cars
for over 30 years. Before retiring this series block Toyota saw
it fit to crown the block with an impressive 24 valve head.
Following
Toyota’s pattern of evolutionary engine development, the 7MG
was a trouble free design- except for the cylinder head gasket problem.
In both turbo and non-turbo varieties, the gaskets tend to start
failing as early as 80,000. It does not matter wether the cars were
either driven extremely hard or easy. Maximum mileage is from normally
used engines, some of which survived to 150,000!
The
bottom line is that these engines can survive all the horsepower
you set it up for as long as you are aware of the maintenance requirement
it needs (head gasket). Keep a fresh gasket on hand and it is capable
of producing a lot of power.
The
later model engines came with the Lexus style oil-filled mounts.
The slight horsepower increase in the latter models came from computer
tuning and exhaust differences. Internally they are identical.
In
competition the 7MGT was handicapped by the heavy Supra body. Although
it won numerous races- there was no major titles for this engine.
Thanks to Japanese tuners (HKS, Greddy, Blitz) the street Toyota
denizens ruled over the competitive models from other manufacturers.
In it’s class and generation the 7MG was the engine. This
same power potential led us to power older Supras, RWD Celicas,
some pick-ups, even a cigarette boat- with these engines.
Modifying
the 7MG / 7MGTE:
BLOCK:
The block is trouble-free, but will not tolerate low oil conditions.
It is a very robust bottom end that will survive mega horsepower
engine build-ups. Since it is a long crankshaft, crack testing is
mandatory between rebuilds. The con-rod small end should also be
rebushed because they are subject to a lot of stress. Maximum bore
should be limited to 85.5mm.
For
normally aspirated engines compression can be raised to a maximum
12.5 compression, after which the dome design starts interfering
with the combustion air-flow. For turbo set-up the compression can
be set as low as 8.0:1. The original pistons did not benefit from
later Toyota practice of piston coating, so for any major projects
forged pistons are the only ticket.
Although
the engine is able to rev high and the bottom end will survive high
RPMs, heavy continuous boost conditions past 16psi will eventually
warp the heads. Judicious use of boosts up to 30psi is not uncommon
and survivable.
The
block decks should be resurfaced to the best finish available. Invariably
the head gasket will have gouged the surface. Make sure that the
aluminum timing cover is on the block when the deck is surfaced,
or else the head gasket will not seal properly. We send the blocks
and head to a special grinding outfit- that machines aircraft components,
and they are able to surface to a mirror finish. Upgrade all the
engine assembly bolts. Replace all the hoses. Keep a spare head
gasket.
CYLINDER
HEAD: The 24 valve head is trouble free, but should be checked for
warpage. There is a common propensity for the aluminum head to deteriorate
around the water passages. Use the best anti-freeze you can get-
more heads become unusable because of material erosion and decomposition-
rather than cracking or warpage. The intake and exhaust ports can
be cleaned up, but port and polishing is not mandatory- there are
other pieces you can spend on that will return more horsepower for
the budget.
Camshafts
and adjustable gears are available to maximize the full potential
of these 24 valve heads. Do not use cams over 280 degrees since
the lower cylinder pressure will cause erratic inputs to the ECU.
On the turbo models, the use of NA cams is an easy upgrade, if you
can find them. In the cam journals to the head, there is a soft
leadlike coating that is normally scoured. We have successfully
polished of all coating into the bare journal and reused the cams
with no problems.
The
valve seals on some engines harden abnormally soon, sometimes even
before the head gasket bows out. Replace the valve seals when you
do a head gasket replacement. Again surfacing (like the block) to
the best finish is mandatory. Use an aftermarket metal headgasket
for maximum mileage in between teardowns.
FUEL
SYSTEM: The stock fuel system for the NA and turbo models is adequate.
For heavy turbo modifications please read the next section. The
VPC designed for the 7MGT can also be used on the NA, an exclusive
Toysport modification. This eliminates the air-flow meter and does
wonders for throttle response and boost transition. For additional
capacity there are 550cc injectors that will drop-in; use a JZA80
(Twin Turbo) fuel pump that is a direct replacement.
TURBO
UPGRADE: The factory turbo is able to run boosts up to 14 psi (1
bar). Trying to boost above this is plain useless. In order of importance-
the exhaust, intercooler, boost controller, ignition, fuel computer,
turbo, vein pressure converter, injectors are the steps in upgrading.
For anything over 14 psi a new block with forged pistons is necessary.
Adjusting compression ratio for a non-turbo being upgraded to turbo,
by the head gasket is not recommended.
The
availability of metal head gaskets in various thickness and composition
is more to compensate for the milling of the head and block, and
slight adjustments in compression. There are 3 types of aftermarket
metal headgaskets available- Stopper, Bead, and Grommet. The Stopper
is a multi-layer set-up that will survive better than a factory
gasket. The Bead has also multi-layer and is a more flexible and
has a raised bead to help seal around the pistons. The Grommet has
an additional seal ring, (like the factory units) and will take
the most abuse.
The
most usable turbo upgrade is based on the CT26 stock turbo. We were
the first company to do this and maintain proprietary specifications.
Some companies also do upgrades, but we are certain our set-up is
the best. A twin turbo set-up is available, that makes the engine
dramatically responsive and powerful- this is based on HKS TwinTurbo
set-up on the old 5MG. There are numerous other single turbo set-ups,
but they are not streetable.
IGNITION
SYSTEM: The simplest most effective ignition upgrade for either
NA or Turbo, are the HKS Twin Power (there are two different units).
Do not even think of something else. The MSD or NGK wires also work
very well as upgrades to factory wires.
Some
Recommended Set-ups:
For
stock configuration: The 7MGE/TE are common engines that reputable
import shops, should be able to service. Machining engine components
should be only trusted to known machine shops, since tolerance limits
are crucial and very specific. There are several good overhauling
gasket sets aside from factory- which are equal to the factory issue,
but as a minimum use only factory original headgasket. Replacing
the exhaust (on both models) produce instant power, the factory
units "crimp" right under the axles- which the aftermarket
units are able to maintain the full diameter.
Hope
this helps... |