|
This article was first published in 2006.
|
In the world of large-cube Japanese turbo engines,
the Nissan RB-series and Toyota JZ-series are the most common choice to modify.
But there’s another engine that lurks just outside the spotlight – the Toyota
7M-GTE. At 3-litres, the 7M-GTE matches the displacement of any other Japanese
turbo engine and boasts a DOHC, multi-valve head for similarly efficient
breathing characteristics. Really, there’s no reason why the 7M-GTE can’t kick
out some huge power numbers – and Sam Rigoli of TRP (Tony Rigoli Performance) is
here to show us how!
Believe it or not, Sam’s highly modified 7M is
mounted in the snout of a Nissan R32 Skyline GTS. Why? Well, when you’ve seen a
thousand RB engines and you want something a bit different, why the heck not?
So when a customer’s 7M-GTE came up for sale, Sam jumped on the opportunity and got
stuck into slotting it in place of the R32 RB engine. The conversion was pretty
difficult, requiring new mounts and cross member, a modified sump and some
stuffing around with coolant passages, linkages and wiring.
In its current configuration, the 7M-GTE is set up
to run big boost together with nitrous assistance all the way through the rev
range. So it’s no surprise the engine has been built to high-performance specs.
At the bottom the engine runs the standard crank with Crower rods and Aries
forged pistons providing a static compression ratio around 8:1. The 7M has a
reputation for popping head gaskets but Sam has no such worries thanks to an ARP
stud kit, copper head gasket and O-ringed head and block.
Despite the level of performance being extracted,
the standard Toyota DOHC head remains untouched – it can’t be too bad, eh? The
only changes are firmer valve springs, which are better suited to the frequent
high rpm operation. Sam couldn’t find aftermarket springs to suit the 7M but a
set of aftermarket 4A-GE springs do the same job. The standard camshafts are
retained but, as seen in this photo, there are adjustable cam sprockets.
Interestingly, these are left at the standard timing – Sam says he hasn’t seen
much of a gain by altering cam timing.
And now to the real power pushers – the
turbocharger and nitrous system.
Sam had his brother, Domenic, whip up a custom
tubular exhaust manifold which allowed fitment of a Garrett turbo and external
wastegate. The turbocharger is a Garrett GT42R teamed with an Innovative 52mm
external ‘gate. Both breathe into a 3 ½ inch mandrel exhaust with a
straight-through muffler.
In its current configuration, the engine is run to
a maximum of 29 psi boost and charge-air cooling is left to an off-the-shelf
A’PEXi core designed to suit the R32. Three inch plumbing runs to and from the
‘cooler and you won’t find a blow-off valve. The inlet to the turbocharger is
usually protected by a K&N pod filter but Sam has recently run the car
without out it - he says it doesn’t make much difference.
The standard 7M intake manifold has been replaced
with a custom manifold that’s different to say the least. What you’re looking at
is a pair of fuel surge tanks welded together with a Ford throttle body hung off
one end. Now that’s creative!
For that little bit of extra oomph, Sam can rely
on a ZEX wet manifold nitrous system. When the boot-mounted nitrous bottle is
opened and a micro-switch on the throttle detects 100 percent WOT, a 100hp shot
of gas is injected into the plumbing following the intercooler. Initially, the
nitrous was solely intended to bring the turbocharger on boost but that idea was
soon abandoned – it’s now run all the way through the rev range at WOT.
Coordinating fuel and ignition timing is a
MicroTech programmable ECU. The fuel system kicks off with an in-boot fuel cell
and a pair of Bosch Motorsport fuel pumps. Larger-than-standard lines take fuel
to six Mazda 13B Turbo injectors and pressure is maintained by a Malpassi. The
ignition is an impressive arrangement with six Bosch coils fired by MicroTech
igniters.
Sam’s R32 is built as a quarter mile machine and
an auto transmission was required for the task. A Ford C4 auto trans has been
fully tricked with billet internals, a trans brake and an external fluid cooler.
The torque converter provides a 4000 rpm stall speed to get the 7M turbo engine
really boosting off the line. A custom heavy-duty tailshaft extends rearward to
a Nissan S15 200SX/Silvia mechanical diff. Fitment of the S15 diff required
modification to the end-plates on the existing inner CV joints.
With an all-up weight of 3150lb (1432kg) including
driver, Sam’s Skyline has had minimal effort invested in weight reduction. Some
of the dashboard has been removed, but this is more than offset by the fitment
of a complete GT-R interior and six-point roll cage. The suspension could also
be improved over the current set-up - the recently installed Tein suspension is
more about handling than straight-line performance.
So what numbers are we talking from this heavily
tuned 7M-GTE?
Well, on the TRP Dyno Dynamics chassis dyno Sam
has seen a massive 570hp (425kW) at the back wheels. This equates to somewhere
around 850hp (634kW) at the flywheel – perhaps closer to 900hp (671kW),
depending on the amount of slip through the transmission and tyre-to-dyno
interface. This output was achieved with 29 psi boost, a 100hp nitrous shot and
Martini race fuel. Peak power arrives at around 6500 rpm and peak torque isn’t
far below – full boost doesn’t arrive until around 5000 rpm... The rev limit is
set at around 7500 rpm.
Mounted in the nose of the Skyline, the Toyota
turbo engine easily runs down the quarter mile in the 9 second bracket. The best
time to date is a 9.58 at 140 mph – though, note that a higher terminal speed
has been achieved on another run. Of course, these times are achieved on slick
tyres – 26 x 10 Mickey Ts.
Despite having what is probably the most powerful
7M-GTE in Australia, Sam reckons there’s plenty of room left for more grunt. A
spare cylinder head is currently being ported and fitted with all the good bits
(including cams) and it’s likely the intake plenum could be refined. Oh, and a
different turbo is worth a try. Reliability is unlikely to be a problem as Sam
has already found the engine’s limit – it seems pistons crack in half when boost
pressure is pushed to 38 psi...
So there you have it – the unloved 7M-GTE engine
making least 850hp (634kW) at the flywheel using an untouched cylinder head.
There’s something for RB and JZ engine fans to think about...
Update!
Sam’s
mega power 7M-GTE engine has now been sold for fitment into a customer’s Datsun
ute! If all goes to plan, Sam will start fresh with another 7M and take it ‘all
the way’ – stay tuned...
Did you enjoy this article?
Please consider supporting AutoSpeed with a small contribution. More Info...
|
More of our most popular articles.
|
|
|
Email a friend
Print article
|