  
 |
Answers to some of the most
frequently asked questions
- How much does a JMR engine
cost?
- Which engine size is
best?
- Can I buy a JMR engine ‘off the
shelf’?
- How do I go about ordering a JMR engine?
- How long will I have to wait for my new
JMR engine?
- I want to build my own engine but
haven’t got access to the necessary equipment to carry out the full
‘blueprinting’ process. Can you help?
- How much will it cost to have my existing
engine tuned on the JMR dyno?
- I’ve already got a
‘performance’ engine. How much will it cost for JMR to rebuild it
properly?
- What kind of performance can I expect from
my new JMR engine?
- When fitting a larger capacity engine,
will I need to strengthen my gearbox?
- How much does a Berg 5 Speed
transmission cost?
- Why does this site keep telling me to
purchase the JMR Performance Guide?
1....How much does a JMR engine cost?
There are
many factors to consider: are you supplying any of the parts? Do you want a
complete engine (supplied with tinware, alternator/dynamo, coil etc or do you
just want a long block (no ancillaries fitted)? Maybe you already have carbs,
009, exhaust system etc.
To give you some idea on cost, here’s a
brief rundown on one of the most popular engines I build: a Type 1 1776cc
engine, producing 102bhp at the flywheel (as featured in the the top left hand
box on the performance summaries page), assuming you have all parts supplied by
JMR.
| Parts: |
- New dual relief crankcase
- Genuine VW 8mm cylinder head studs
- Universal case fitting kit
- Crankcase nut & bolt kit
- Main bearing dowel pins
- Main bearings, rod bearings and two sets of cam
bearings (double thrust)
- 69mm stock crank
- Engine gasket kit and flywheel oil seal
- Crank gears, spacers, woodruff keys and distributor
drive shaft, inc shims and spring
- JMR rebuilt and balanced stock rods (+/- 1 gram)
- Genuine VW 200mm flywheel
- Berg 36mm chromoly flywheel gland nut
- Dual Dellorto 40 DRLA twin choke carbs
- Inlet manifolds, carb linkage and air filters
- Fuel hose
- Sachs 200mm clutch pressure plate, centre plate and
clutch release bearing
- Crankshaft pulley
- Crank pulley tinware
- Engle 110 cam with aluminium bolt on cam gear
- Scat lightweight cam followers
- Mahle 90.5mm piston and cylinder set
- New 1600cc twin port cylinder heads
- Berg unleaded valves
- Scat single heavy duty valve springs
- Hardened colletts
- Chromoly valve spring retainers
- Valve spring shims
- Berg 3/8” chromoly pushrods
- Berg HD bolt together rocker shafts
- Stock VW 1.1:1 rocker arms
- Swivel feet valve adjusters
- Rocker pedestal shims
- Valve covers
- Bosch 009 distributor
- Berg 26mm oil pump
- Berg pump cover, with take off
- Oil filter mount
- Fram HP1 oil filter
- All necessary oil fittings and hose
- Bugpack 4 into 1 header
- Bugpack single quiet pack silencer
- J-pipes
- Silicon ignition leads
- Bosch W8AC spark plugs
- Stock fuel pump, pump pedestal and fuel pump pushrod
- Oil pressure switch
- Engine oil
- Dipstick
|
| Machine
work: |
- Bore case for 90.5mm cylinders
- Spot face case savers
- Drill and tap for full flow oiling
- Drill and tap main oilways
- Lighten flywheel
- 8-dowel crank and flywheel
- Dynamically balance crank, flywheel and pressure
plate
- Hone cylinders
- Set piston ring gaps
- Machine pistons for correct deck heights
- Balance pistons +/- 1 gram
- Bore heads for 90.5mm cylinders
- Semi hemi cut combustion chambers
- Competition three angle valve job
- Blend valve seats into ports
- Match port inlet manifolds to cylinder heads
- Machine pushrods to correct length
|
| Engine Assembly:
|
| Trial assemblies are carried out to determine: true
top dead centre, piston deck heights, dial in cam, cam to follower clearance,
set rocker arm geometry, cam end float, rod side clearance, valve spring
installed height, installed length of head studs, oil pump drive gear
engagement, compression ratio, crankshaft endfloat etc. |
Following final
assembly:
the engine is transferred to the dyno and hooked
up to oil pressure, oil temperature, cylinder head temperature, exhaust gas
temperature, fuel pressure and air fuel ratio senders. With the rocker gear,
pushrods and spark plugs removed, the engine is spun over until oil pressure
registers on the gauge. With those parts refitted, carbs primed and ignition
timing set statically, I fire the engine and bring it up to 2,500rpm and keep
it there for 20 minutes. This period of running is critical for proper cam
break in. After the engine’s first 20 minutes, I leak test all four
cylinders to check the piston rings are sealing and there are no leaks past the
valves. Ignition is set stroboscopically and carbs synchronised. Testing under
load then commences. This procedure ensures the correct combination of
carburettor venturii, main, air and idle jets are selected for that particular
engine, providing the optimum balance between power, reliability and fuel
economy. Finally, I leak test the engine again, just to check everything’s
as it should be. Each engine is supplied with a computerised performance
summary, depicting torque and horsepower throughout the rpm range. Once the
engine has completed these tests, it’s ready to go! |
So, total cost for
all this? At time of posting the above engine would cost in the region of
£4200.00 (inclusive of VAT and free mainland UK delivery).
A more in depth look at the
procedures involved in the build up of one of these engines is featured in the
JMR Performance Guide |
2.... Which engine size is best?
For a street engine, in otherwords a daily driver, limit cylinder size to
90.5mm. This gives 1776cc with the stock 69mm crank. Next size up, 92mm
(1835cc) has a thinner cylinder wall and won’t give as good long term
service as the 90.5s. If you have a case and heads that have previously run
with 92s, you can switch to the thicker 90.5s as the outside diameter of the
two different bore cylinders are the same. 94mm cylinders (1914cc with the
stock crank), need case and heads opening up further still. The 94mm cylinder
has a thicker wall than the 92s but has less depth of cooling fin, therefore
can’t dissipate heat as effectively as the smaller sizes.
| ENGINE CAPACITY CHART (cc) |
STROKE/
BORE
(MM) |
69 |
74 |
78 |
82 |
84 |
86 |
88 |
| 85.5 |
1584 |
1699 |
1791 |
1883 |
1929 |
1982 |
2121 |
| 90.5 |
1776 |
1904 |
2007 |
2110 |
2161 |
2213 |
2264 |
| 92 |
1835 |
1968 |
2074 |
2180 |
2234 |
2287 |
2340 |
| 94 |
1914 |
2054 |
2165 |
2276 |
2332 |
2387 |
2442 |
If you plan on building a fine weather, bring it out for
the shows in summer, low mileage street car, then the 94s are worth
considering.
87mm cylinders (1641cc) are a popular conversion because
they fit the case and heads without machining. To achieve this, they obviously
have a thinner cylinder wall. If you’re on a tight budget, consider them
as an option but because of the reduced wall thickness they won’t give the
kind of service a set of stock 85.5s (1584cc) or the bigger 90.5s (1776cc)
will. I definitely do not recommend they be used in a bus engine: the extra
weight of the vehicle makes the engine work harder than if fitted to a Type 1
and creates more heat.
Excessive heat will distort the cylinder and a
round piston doesn’t take too kindly to being forced up and down a non
round hole. Result: blowby past the rings, loss of compression, pressurisation
of the crankcase, burning oil, dilution of the petrol with oil etc etc. Not a
good thing to have going on in your engine.
The worst piston and
cylinder sets of all are the 88mm ‘slip in kits’. These are so thin
they can barely contain the pressure of combustion at the cylinder head end and
it’s not uncommon to see the cylinders split after only a few hundred
miles. I don't use them - ever!
The 1300 to 1600 conversion kits are
also bad news, for the same reasons. Anybody who tries to sell you a set of
these is just out for your money. Take your custom elsewhere.
Stroker motors:
If you can
afford it, use a stroker crank. A correctly built long stroke VW engine is an
absolute pleasure to drive on the street. The additional torque is instantly
noticeable. Naturally it costs more to go this route: parts are more expensive
and additional work is required to various engine components to accommodate the
longer throw of the crank. There are many factors to consider before choosing
which way to go and finance will be the ultimate decider but for a good all
round performer on the street, 2007cc or 2110cc (78mm or 82m stroke, 90.5
pistons and cylinders) is a good choice. For low mileage street cars, 82mm
stroke with 94mm pistons (2276cc) is a good route to go.
Call for more
info.
3.... Can I buy a JMR engine ‘off the
shelf’?
No. All engines are built to order.
4.... How do I go about ordering a JMR
engine?
If you’re thinking about buying a JMR
engine for your VW, I’ll need to discuss your requirements e.g.
- what vehicle will the engine be fitted to?
- how will the vehicle be driven e.g. daily driver, street
racer, race only etc.?
- are you looking to maximise low end torque (ideal for Type
2s)?
- do you want absolute maximum horsepower?
- maybe you want a good spread of torque throughout the
engine’s operating range?
- and probably most importantly: “what budget are you
working to?”.
Obviously, that last question is an important one,
because it determines the overall specification of the engine. There’s no
point trying to build a 2007cc engine on a 1776cc budget. You may not
necessarily feel you know all the answers to the above points but part of my
job is to determine the best combination of parts and overall specification for
the type of use you will be putting your new engine to. Based on the
information you have given me, I am in a position to use my experience to
tailor an engine specification to suit your requirements and budget. Consisting
of six pages of A4, it lists every single engine component, with prices for
each part. All necessary machine work procedures are individually itemised and
priced, and there are separate totals for engine assembly and dyno testing.
This way, you can see where every single penny is going. Having read through
the spec sheet, you may have some questions; want to make certain
upgrades/downgrades. I’ll make sure any proposals you have won’t
upset the combination or detract from engine reliability in anyway and finally,
as long as I’m happy the specification will deliver as expected and
you’re happy with the price, the order can be placed.
To
place your order, I require a deposit of 50% of the total engine
price.
5....How long will I have to wait for my new JMR
engine?
Engine delivery varies depending on work load but
on average your engine will be ready for collection 10 - 16 weeks from the time
of placing your order. More exotic combinations can take longer due to
occasional problems with parts supply. Once I’ve received your deposit,
your name joins the queue. When your name comes to the top of the list, your
engine is built.
6....I want to build my own engine but
haven’t got access to the necessary equipment to carry out the full
‘blueprinting’ process. Can you help?
Yes. I have several customers who felt happy about
their ability as far as bolting an engine together goes but when they read my
‘Performance Guide’ and saw the variety of engine assembly techniques
and procedures I carry out, they realised that in order to achieve anything
like the same build quality, they’d have to do something more than just
purchase a collection of parts and bolt them together. Many home engine
builders just don’t have access to the wide range of tooling and equipment
needed to build an engine ‘properly’. For instance, how many people
go to the trouble of measuring piston deck heights and if they do, what are
they going to do to correct any discrepancies? How about dialling in the cam
and setting rocker arm geometry correctly?
Here’s an
example of one particularly successful joint effort: I was contacted by Kevin
Flanagan from Darlington, who wanted to build a Type 1 1776cc engine which
would be used on the road but primarily his interest was to race in the VWDRC
Street Class. I carried out all the machine work necessary to allow him to take
away enough parts to assemble the bottom end of the engine (case halves bolted
together, crank, rods and cam installed). He then returned the engine for me to
trial fit the pistons and cylinders in order to measure deck heights. I
machined the pistons and balanced them, set rocker arm geometry and made a set
of pushrods to the appropriate length. Kevin carried out his own cylinder head
porting work, I reworked the valve seats, cut for dual valve springs and bored
them to 90.5mm. He now in effect had a performance engine ‘kit’,
which he took home and when correctly assembled would give him the satisfaction
of having built the engine himself and most importantly, the knowledge it was
going to work a lot better than if it had just been ‘thrown’
together. The engine was returned for dyno testing and sure enough, the figures
were up in the region we’d hoped for: 123 horsepower @ 6000rpm. After a
season’s racing (regular 14 second quarter miles - shaming many opponents
larger cc efforts), Kevin upgraded to a 1914cc engine combination. With a raise
in compression ratio, more work to the heads and another dyno session, we
achieved 156 bhp! Kevin’s efforts were rewarded on the track with a 13.6
second timing ticket. Not bad for a road legal car running on street tyres and
a totally stock 1300 transmission!
I have other customers who have
gone through the same routine. If you feel confident in your ability to do the
same, contact me and we can discuss the best route to take. It will involve at
least a couple of trips to the JMR workshop but at least you will have the
confidence your engine has been set up correctly and isn’t just another
run of the mill ‘bolt it together and hope for the best’ motor.
7....How much will it cost to have my existing
engine tuned on the JMR dyno?
A full day on
the dyno will cost you £300.00. If you want to take maximum advantage of
that time, make sure the basics are right;
- Is the engine running on all four cylinders?
- Are the valve clearances set?
- Fit new spark plugs
- If the engine has points and condenser fitted, make sure
they’re new
- Does the carb linkage work correctly?
If I have to spend time putting the basics right,
that means less time testing. I’ve had people arrive with engines in such
a poor state that in some cases I’ve had to spend several hours working to
correct the faults. In most instances these faults could have been addressed by
the owner. I’m quite prepared to do this kind of work but it means
you’re paying for time that could have been spent more productively
testing the engine.
The only alternative to setting your
engine up on the dyno, is to take it to a rolling road. The principle is the
same, however load is applied to the engine via the rear wheels rather than at
the flywheel (as on the dyno). A major advantage of testing on the dyno is
unrestricted access to the carburettors and the engine in general. Jet and
venturi swaps are easily made, whereas the average rolling road operator may
not be too keen on delving into the restricted access offered by a twin carbed
engine fitted to the back of a VW.
Depending on how far out of tune
your engine was prior to the dyno session, will determine how great the before
and after effect is. I’ve seen engines run so weak at the top end of the
rpm range that when jetted correctly have picked up as much as 35 to 40
horsepower! The fact is these engines have the horsepower potential built into
them but because the crucial final step of dyno testing hasn’t been taken,
it’s all going to waste. Some of these people have spent thousands of
pounds putting together an engine and for some reason won’t go the extra
round to get what it was they were after in the first place: MORE POWER!
Also many people aren’t aware of the danger their engine could be in
if run for any period of time with carb jets of the wrong size fitted. Too lean
and you’ll melt a piston or even worse, destroy the whole engine. Slightly
too rich shouldn’t hurt anything other than power and your pocket (extra
fuel expense). In many cases the engine will run a little rich at lower rpm and
as rpms increase, it leans out. A disaster waiting to happen.
If your
engine has the right combination of components and is jetted correctly, power
delivery will be smooth: no flat spots or hesitation. Fuel consumption will be
improved, your engine will last longer, it will make more power, run cooler and
be a pleasure to drive.
| For more
info on the JMR Stuska Dyno, see the Performance Guide |
8....I’ve already got a ‘performance’
engine. How much will it cost for JMR to rebuild it properly?
Regardless of who built your engine or what components have been used, as
far as I’m concerned in whatever format you supply the engine (partly or
fully built), it is purely a collection of components. I will not for example
take on a short block (engine minus barrels, pistons and heads) and build up
the top end assembly. No exceptions.
The only way I will allow an
engine to leave the JMR premises with the tag ‘built by JMR’, is to
have put all the parts through the same checks and build procedures as one of
my scratch built engines. This is the only way to ensure each and every engine
built here is done to the same high standards I’ve built my reputation on.
E.g. this means the crank, flywheel and pressure plate have to be
dynamically balanced; even if you’ve already had this done previously.
There is no way to tell visually if this has been done correctly and the only
way I can guarantee the quality of work on any engine I build is to approach it
from the standpoint that nothing has been done properly..
Here’s a case history that proves my point:
I had someone contact me a couple of years ago with a view to
building a Type 1 2007cc engine. To protect the names of the innocent,
I’ll call him Mr.X. I put together a specification but it obviously came
to more than he was expecting. Next thing Mr.X contacted me to say he had
acquired a 2007cc engine from elsewhere and all it needed was a session on the
dyno before being fitted to the vehicle
Once running on the dyno and
warmed up, I applied load and started to push up the rpm. The oil pressure
nose-dived so I instantly shut everything down. Initially I thought there was a
problem with the wiring from the pressure sender due to the rapid movements of
the oil pressure gauge. After fitting a new gauge, sender and wiring I still
had the oil pressure problem. Then followed several hours worth of replacing
the oil pump, testing, checking the relief valves, testing, checking the oil
pump pick up pipe, testing, etc, etc. All to no avail.
Reporting the
problem back to Mr. X, he gave me the go ahead to dismantle the engine in order
to try and track down the problem. The 78mm forged crank turned out to be cast
iron. The 40mm x 35.5mm heads were stock 1600s. The flywheel had been drilled
for 11/32” dowels but the crank only had 8mm dowels. The rods weren’t
balanced. How about 45 grams between lightest and heaviest! Nine times the
difference allowed by VW! Needless to say, Mr.X wasn’t very happy. He
commissioned me to rebuild the engine with a forged crank and supply a set of
ported big valve heads along with other mods. The end result was he got his JMR
engine but it had cost significantly more than if he’d gone that route in
the first place. I’m not apportioning blame to Mr.X for any of this. After
all, we all like to think we’re getting a bargain but more often than not
the bargain doesn’t turn out to be what it first seemed.
Oh
yeah, that oil pressure problem: it turned out that instead of plugging the
outlet of the oil pump, as is normal when utilising a full flow filtration
system, the original ‘engine builder’ had glued a piece of threaded
bar into the oilway between the oil pump and where the case is drilled and
tapped for it’s oil return fitting. This came loose and was free to float
up and down this passage way and as rpm increased so did the pressure from the
pump, pushing the threaded rod up the oilway blocking oil supply to the main
bearings. Hence the loss of pressure. Nice work!
Stop
Press
In an attempt to reduce the length of time customers have
to wait for their new JMR engine and/or transmission, we are currently only
taking engine and transmission orders where all parts are being supplied by
JMR. Invariably, the task of correcting the problems associated with third
party engine builds involves far more labour time than when building a new JMR
engine, This has the effect of delaying everyone else in line, including those
customers who are having all parts supplied by JMR. People who are leaving the
entire parts supply and engine build to JMR must receive priority and in order
to reduce delivery times we will not be taking on anymore reworks of engines
and/or transmissions that were not originally supplied by JMR.
9....What kind of performance can I expect from my new JMR
engine?
Horsepower and torque aren’t the only
factors which will determine things such as 0 to 60 mph times, 1/4 mile times
and speeds etc. Many other factors have to be taken into consideration:
- vehicle weight
- aerodynamics
- gearing
- overall diameter of the rear (driven) wheels
- rear wheel grip (traction)
- gear shift rpm
- transmission efficiency
- weather conditions (temperature, humidity and barometric
pressure)
- driver ability
All of the above and more will have an effect on
overall performance of the vehicle.
Every engine built at JMR
is tested on the JMR Stuska Dyno. I take the horsepower and torque figures
derived from the dyno test and put them into a computer program along with
other data relevant to the vehicle in which the engine is to be fitted. The
resulting info provided by the program will give a very accurate reflection of
expected performance. Each and every engine built and/or tested at JMR receives
a print out of this info.
On studying the printout you’ll learn
where optimum shift points are and see how suited the gear ratios you have are
for their intended purpose.
This information also comes in useful for
planning future upgrades/modifications. I can input the proposed alterations
into the computer first to see how much of an improvement (if any) you can
expect.
10....When fitting a larger capacity engine,
will I need to strengthen my gearbox?
This
will depend to a large extent on the amount of power and torque the engine has
and the way in which the vehicle is driven. I have customers driving around
with 150bhp engines bolted to totally stock transmissions and reporting no
trouble. On the other hand, there are others with 100bhp who have broken
differentials, axles and gears. The difference is in the way the vehicles are
driven.
Probably the best way to try and damage your gearbox is to
drag race it: trying to gain traction from a standing start with high rpm. If
the tyres grip, rather than spin, you’re putting a tremendous shock load
through the whole drive train. Usually the first thing to break will be the
spider gears in the differential. Next to go (on swing axle cars) are the
axles. On IRS cars, you’ll break CV joints.
Parts are available
to beef up the transmission and if you think you have the potential to break
parts, it makes sense to have the appropriate pieces fitted. The Performance
Guide has a whole chapter on strengthening the transmission.
11....How much does a Berg 5 Speed transmission
cost?
This will depend on how many
‘beef-up’ goodies you need. That will be determined by the
engine’s torque and power output.
I wouldn’t consider using
a Berg 5 speed unless you have at least 100bhp. Many people are under the
illusion the only thing preventing their car going faster is the fact
they’ve run out of gears. A stock 1600cc engine has 50bhp. Give it a tall
5th gear and you may think it’ll be capable of 150mph. Not so! When you
double the vehicle’s speed (say from 30mph to 60mph), wind resistance
increases by a factor of four! Gearing isn’t the only solution to higher
speeds. You need more power too.
If you’re considering a 5 speed
transmission for your car, gear it up to enhance the characteristics of the
engine: select ratios that will ‘drop’ the engine rpm into an area of
optimum torque. This will provide quicker acceleration. Typically this will
involve the use of closer ratio 3rd and 4th gears with an ‘overdrive’
5th to provide relatively low rpm high speed cruising.
Price for a
fully blueprinted Berg 5 speed assembly, including Super Diff, HD sideplate,
Super Beetle 3.78 and 2.06 1st and 2nd gears, close ratio 3rd and 4th gears,
overdrive 5th and Berg 5 speed shifter is around £2,600.00. Call for
further details.
Lots more info on gearing, parts selection and Berg
5 speeds in the JMR Performance Guide
12....Why does this site keep telling me to
purchase the JMR Performance Guide?
I wrote
the ‘JMR Performance Guide for the Aircooled Volkswagen’ in order to
provide answers to the vast majority of questions I was being asked day in, day
out by people on the phone, fax, e-mail, calling in at the workshop, at shows
etc. Despite the amount of information appearing in the specialist magazines,
books and being offered by other ‘engine builders’ , it’s clear
there’s an awful lot of bull**** about.
I took the opportunity
to provide answers to these questions and also provide information on a vast
array of topics relevant to anyone looking at improving the performance of
their VW.
The Performance Guide also takes you on a guided tour of
the services available from JMR and via the engine build chapters will give you
an understanding of what it takes to make a VW aircooled engine truly
’perform’.
The Performance Guide isn’t a profit making
venture. Due to relatively small print runs, production costs are high. The
purchase price covers those costs.
If you’ve made it this far
through the JMR web site, it’s probably safe to assume you’re
interested in the contents. The Performance Guide gives you even more.
If you’d like more information of the type contained in this site,
order your copy today.
Please don’t expect me to spend time
composing replies via fax or e-mail, or on the telephone, to questions
I’ve already taken the time, effort and trouble of putting into writing
within the contents of the Performance Guide
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