By 1965, The Morgan Company was aware that
the power output of its four cylinder engine
was too small for the demands of many
customers. The Company's waiting list
had shrunk to two years.
The problem was to find just the
right power plant. Triumph's
solution had been to fit a great
straight-six into the TR-5 but this
engine was too high to fit into a
Morgan. Lotus's twin-cam was too
fragile and the Ford V-6 was too heavy.
In 1966, as a by-product of an unsuccessful
take-over feeler from Rover, Peter Morgan was offered
a
crack at a new Rover purchase from Buick, a lightweight
aluminium V8 called the 215 or the Jetfire
which (in 1961-62) had been standard in the Buick Skylark
and Oldsmobile F-85 (though each had different heads, intakes and exhaust
arrangements).
Maurice Owen, a race engineer, was engaged to experiment with the engine's possibilities for Morgan and worked with drawings until he found an old Buick engine to fiddle with. The engine was literally jammed into a Plus 4 and was rolling in early 1967. After some Leyland/Rover problems, the Plus 8 went into production in 1968 with 20 cars delivered. As a reference point for power, an unmodified 4/4 of that time created about 75bhp. The first Plus 8's (1968 to 1972) put out an unmodified 160.5bhp or 170hp on the American standard, a significant boost of power.
N.B. BHP is a measurement of the actual usable power (not calculated power) measured at the output shaft (usually the crankshaft) rather than at the drive shaft or the wheels. Thus none of the auxiliaries (gearbox, generator, alternator, differential, water pump, etc.) are attached. It is called the brake horsepower because the shaft power is usually measured by an absorption dynamometer or "brake." This is not the brake on the vehicle's wheels but a testing device applied to the shaft. This instrument is applied to stop or absorb the rotation of the output shaft and returns a value. This standard is considered a far more reliable indication of effective horsepower than the US HP.
In January of 1974, the compression was reduced in stages to meet the first early European emissions requirements and the power dropped to 143 bhp. At the end of 1976, the successor engine to first the Rover V8 was introduced called the SD1 (Specialist Division 1) and power increased again (12bhp) and reliability increased mightily.
In 1982 Stromberg carburettors replaced the SU's as Rover again struggled to meet European emissions standards (calling for automatic chokes controlled by water temperature) while still maintaining the power. The Strombergs did the trick and horsepower held at 155bhp.
In 1984, Morgan offered a few new fuel-injected version
of the high performance "Vitesse" SD1 engine as an option. The Vitesse
engine, fitted with a new gearbox, was designed by Rover to be a
competition n motor. Power jumped dramatically on the first delivered
Morgan Vitesse EFI model produced without any compromise to the car saving
a cut away of the bonnet hinge to accommodate the plenum chamber of the
engine. This Plus 8, smaller and significantly
lighter than today's version, with the tubular
manifolds and twin exhaust of the day (and
Morgan's new and first rack and pinion
steering a standard), left the factory
unmodified with an amazing 205bhp
and an estimated 248lbft. of torque
at 4000 rpm.. It was capable of 0 to
60mph in 5.15 seconds. A limited
number of these optional Vitesse
EFIs were produced in the period
from September 1984 to early 1985
before the weight when up, the
exhaust system became a single pipe
and engines were altered.
All Plus 8's were fuel- injected after January, 1987.
The power of the Plus 8's began to drop again in 1985 (190.4 bhp) and the torque tumbled to 198 lbft. with the introduction of more emission safeguards embodied in the addition of catalytic converters, the return to a single from dual exhaust. Structural changes gradually increased the weight from 1884lbs to 2068lbs. Power fell slowly but continually to 162bhp until the production in June of 1990 of a re-bored version of the V8 increasing capacity from 3538cc to 3946cc. The horsepower climbed back up to near 1985 standards and the torque was even better at lower revolutions such that Autocar (May 1991) observed that the 1991 Plus 8 (0-60 in 6.1 sec.) showed its rump to a Porsche Turbo at any speed up to 80mph.
Presently, the Morgan website still lists its 3.9 litre
engine as producing 185bhp though this figure is dated and 190.3 bhp is
a more accurate figure. (The U.S 4.0 Plus 8 produces about 186.7bhp.) The
site also shows the 4.6 litre version but does not indicate performance
specifications or details but the Morgan dealers list the 4.6's power at
194.4bhp with 260ft/lb of torque. This too is probably inaccurate and an
appeal to Land Rover directly gives more plausible figures of 218bhp and
300 ft/lb.s of torque.
N.B. I have written a supplement
to this article including a power-to-weight analysis
in response to questions on this article.
N.B. Please note this article does not apply to
Plus 8's made for the U.S. market during the
period from 1976 to 1996. Please refer to an analysis
entitled Made
in the U.S.A (1971 to 1996).
J.E. Engineering, an advance British group specializing in the Rover V8 performance engine has recently produced a 4.5 litre based on the same engine block that reputably produces the better part of 300 horsepower and Rpi sells a 5.2 litre model that can be camshaft adjusted to produce greater torque or horsepower according to your needs. The dyno claims that the engine produces 334 bhp at 5500 rpm.
N.B. As a side note here, there has been much said about the frightening mysteries of fuel injection. It is bunk. Fuel injection systems were clouded with rumours by the manufacturers wishing you to service at their dealers. The Plus 8 standard ECU (Electronic Control Unit) has an inbuilt adjustment factor of 25%.
The Rover Vitesse / Buick Jetfire are amazing lumps. With
mild attention, they easily produce the magic one-for-one solution or one
horsepower per pound
weight. For this reason, they are a popular engine
swap choice among hot rodders and kitcar
builders. They collect myths and fancy
like few others. I will try to distinguish
some from fact from fiction.
INSTALLING A NEW EXHAUST
SYSTEM
There is no argument that an
improved exhaust system is good
for the car. The engine will breathe
better and engine temperatures will
drop. As the factory system installed is
very restrictive, a free flowing change is
a fine adjunct to other major alterations to the engine.
A stainless or treated system is also prettier
and maintenance free.
However, exhaust is exhaust. It is not a prime ingredient
to combustion and happens after rather than before that fact. Aside from
mild adjustments to back pressure, the horsepower claims of exhaust
system sellers are simply ridiculous. You will be lucky
to obtain an extra 2-3% power from any exhaust system only but it will
allow you to effect other changes that will produce much more power than
that. A twin big bore system (2 diameter) is a start and will go well with
flow-thru silencers (1976 style). The sound is simply incredible.
N.B. Remove your resonators. They are too far away from the heat to properly clean themselves so they rust quickly, block the airflow, reduce power and sound lousy. Please beware of the local emission requirements if you choose to throw away your catalytic converters and CHANGE THE RESISTOR (check out the Plus 8 page on "Cats").
Considering the price of a good full exhaust system from manifolds to tailpipe, assume you will pay about $800.00 per horsepower with the aesthetics unconsidered.
There is one codicil to this section that is the difference between a single and dual exhaust system. For those of you unfortunate to have a Morgan with a single exhaust system. Cars tested before and after a switch from a small bore single system with manifolds to a dual large bore system with tubular heddars have shown remarkable power increases far beyond the minor percentages indicated above.
This is the best bargain for your horsepower dollar. The standard paper filters or worse foam filters restrict airflow and thusly the engine. They dirty up over time causing further prejudice to your power.
K&N produce high-capacity, low restriction washable filters that fit without any modification . Part No E-2350 for later Morgan has dimensions of 5 5/16"od x 3 1/2"id x 6 1/2" h. and Part E-2330 for earlier Plus 8s and is 5 3/8"od x 3 1/2" id x 2 9/16" h . Buy the full kit with cleaner and oil spray) The cost is about $65.00Can and they can be ordered through Canadian Tire or any auto supply specialist. You can find K&N's contact particulars on the GoMoG General Parts Directory. You can assume a 4-6% power increase for three minutes of work. That works out to approximately $6.00 a horsepower.
Another goodie but you have to be careful.
Dyno tests have shown a 7-11bhp boost
is possible by advancing the engine
timing up to four degrees more
BTDC. The care comes in for three
reasons.
A) You might have trouble with
this timing with consistently hot
weather ie.95F+;
B) You have to use premium gas or
better still octane boosted premium gas;
C) Your emissions will increase which may cause a problem
in annual testing jurisdictions.
The best way to try this trick is to increase the timing one point at a time and test drive the machine up a hill after each adjustment. When the car starts to "ping" reduce one point and there you are.
Costs per horsepower are 0...only time and optionally
the ongoing factor of premium gas and/or
octane boosters.
Your ECU can be reprogrammed with a performance chip or, supposedly better still, replaced with a nonprogrammable chip that can be adjusted specifically to your engine with the proper program, fuel system mapping and a laptop. Good luck with the latter.
A smart specialist chip can, however, can deal with the mid-range power slump of the hotwire versions and improve gas mileage. Power gains here are from 10-20 horsepower and costs of the performance chip are approximately $700.00 or $35-70 per horsepower.
Fit a supercharger kit. Most systems today have knock sensors which make it a reputably simple bolt-on. (Some modifications to the bonnet may be necessary.) Power gains can be up to 55bhp but only if the car is re-chipped (without re-chipping one can expect 12-18 bhp). The cost is approximately $5,500.00 or $100-$450 per horsepower.
N.B. There are increasing rumours of an unequal fuel distribution produced by the Eaton supercharger in conjunction with the standard configuration GEMS Rover V8. I would suggest you inquire specifically on this issue and scan this message thread.
There are a dozens of other improvements to performance
that are possible with this marvellous engine. At some point, however,
one starts getting a little too far
from the original to honestly call the car a Morgan.
Each of us must make a choice of how
far we wish to go and why.
One can assume the maximum hp
one can coax from injected 3528cc
or a 3946cc while still being able
to smoothly drive it to the
pharmacy is in the neighbourhood
of 265 hp. A carburetted version
can go as high 235 hp without
sacrifice of a smooth idle.
There are three facts to consider. Firstly,
full performance engines run well at mid
and high revolutions and poorly at low. That type of
power will not help you unless you are a racer only.
Secondly, most power adjustments are concurrent
applications not cumulative. In other words, many power
increasing modifications presume others will also be done so that you can
assume a power gain from each but only in concert. Lastly, each improvement
puts a strain on the whole system and a previously unnoticed weak area
can "pop" up to give you headaches.
A quick overview of other changes;
1. UPGRADE THE DISTRIBUTOR,
COIL, IGNITION AMPLIFIER AND LEADS
Options here include a Mallory Dual Point with or without
Vacuum Advance or a Mallory Unilite with
Vacuum Advance (must be purchased with a resistor as
it runs on 7-8 volts and a noise reducer so
you can play a radio) OR you can try a MDS coil with
a standard Buick 215 distributor will do as nicely, OR clean out your Rover
unit.. and upgrade only the coil.
DISTRIBUTOR ISSUE
The configuration of the Morgan front end and the
placement of the distributor make for water access into the distributor.
Inevitably, this leads to rust within the distributor, a poorer spark,
poorer combustion and trouble during damp conditions. All this leads people
to believe that the Lucas distributor is the culprit. The solution is quite
simple. Clean your distributor thoroughly and regularly. Be careful, as
more than one RR owner has found the rotor arm stuck fast to the distributor
shaft when trying to replace it during routine maintenance. Pulling up
too hard on the rotor can break the plastic C-clip that holds the upper
and lower parts of the distributor drive shaft together. If it is stuck,
try hammering DOWN with a screwdriver or chisel and break it into pieces
to get it off the shaft.
IGNITION LEADS
The ignition leads need replacing at regular intervals;
failure to do so results in noticeable misfiring. To avoid this, invest
in a good set. Magnecor "Blues" will serve the purpose well..
IGNITION AMPLIFIER
On all distributors from 1976 to 1982 and from 1986 on,
the ignition amplifier module (on the outside of the distributor) can give
trouble. This item converts the magnetic impulses from the distributor
into a larger signal to fire the primary circuit in the ignition coil.
Often, the heat build-up under the hood will eventually cause this amplifier
module to fail intermittently, stalling the engine. The faulty
unit can become so sensitive to temperature
that even a minute or two of cooler air
provided by opening the hood can get
it working again. Land Rover has
since superseded this part with a
more robust amplifier module.
The 1982 to 1986 distributors
(35DM8) have the amplifier well-
protected be mounting it remotely
under the cover of the coil bracket
attached to the inner wing.
2. INSTALL AN ADJUSTABLE
RISING RATE FUEL REGULATOR
This cute little item increases your fuel pressure
when you are accelerating and is adjustable as well and
effectively results in "reprogramming" you fuel delivery.
Unfortunately, it will only work with engines having the Bosch "flapper"
airflow meter with the analogue ECU.
3. INSTALL A WEBER CARBURETTOR
Try the 4 barrelled 500 CFM. This carb will fit into
a Morgan using a Edelbrock Offenhauser
"low rider" intake manifold. The Weber is easy to set
up and easy to maintain, rejet and rebalance unlike
the commonly used 4 barrelled Holly 390 CFM. The Holly
venturi size is too small for a heavy breathing engine resulting in additional
vacuum, which in turn confuses the vac secondary. Its design also forces
you to spend too much time assembling and disassembling the thing to get
it right. All to no end or a sacrifice in power in comparison to the better
designed Weber.
4. INSTALL PERFORMANCE INLET MANIFOLD,
see the Offenhauser from Edelbrock above. The manifold
can also have the ports widened and polished for better airflow.
5. INSTALL A PERFORMANCE CAMSHAFT
There are many made for this engine and each have advantages
and disadvantages depending what you
expect from your motor. Check out the lines of Oselli,
Kent, Piper, Crane, J.E. Motors and Crower.
(The writer prefers the Crower Hydraulic Power Compu-Pro
Performance Level 2 or the Piper 270-272). Calculate 0-25 bhp depending
on which of the "reasonable" camshafts you choose.
It is wise to be very careful with the choice you make here. It is not simply of decision of how much power you want but "where" you want it. A cam developing large amounts of power at high rev's are good for those of us who specialize in Autobahn racing in a straight line with hands clutching the wheel and a crazed grin frozen on one's face for hours. On small country roads this same camshaft will perform poorly.
6. UPGRADE THE TIMING CHAIN
Install a duplex venier timing chain. (This is an eventual
must anyway as the standard Rover chain stretches very badly over time.)
7. STROKE THE ENGINE
This can be done with seasoned 3.5 or the 3.9 all the
way up 5.2 litres. (Rimmers
advertises a 6.0l engine!) However, if you
are going this far.. why not a new engine
block at a much cheaper price? New
4.6 blocks with their structural
improvements and better oilways
can be had for 2400 USD making
stroking a less than ideal solution.
The parts of the engines remain
interchangeable.
There are other possibilities but we are
now closer to NASA than Malvern Link.
For those of you with a fascination for power
or a yen for the "fastest" Morgan, I strongly
suggest that you adopt a "buyer beware" attitude.
A good automobile is a well harmonized compromise of
many parts. Also, never believe the claims of your "expert".
No one knows the true performance of an engine without a proper dyno testing.
If you have not done this, your claims to horsepower are most likely
wishful thinking.
Come to think of it though, there is nothing wrong with wishful thinking. Costs are nothing, installation time is negligible and horsepower gains are unlimited.
Should you wish further details, please email me .