Revised 6/8/08
We have been working with Colt Cams to come up with FOUR new
SHO NUT Performance exclusive cam profiles.
Colt Cams is a company that specializes in high-quality cam grinding for
a variety of vehicle applications, now including the SHO. Our offering is composed of four new cam
sets:
SHO NUT Performance Tri-Flow cams
SHO NUT Performance Plus 40 cams
SHO NUT Performance Plus 20 cams
SHO NUT Performance Plus 10 cams
The numbered name implies the additional lift
over a stock MTX cam for the first two numbered cams (Plus 40/20), and a
natural progression of numbers for the third numbered cam (Plus 10) (See below)
As a primer, here are the measured specs of the
stock cams:
MTX Intake 0.348”
Lift, 205° Duration @ 0.050”
MTX Exhaust 0.328”
Lift, 201° Duration @ 0.050”
ATX Intake 0.328”
Lift, 201° Duration @ 0.050”
ATX Exhaust 0.328”
Lift, 201° Duration @ 0.050”
The ATX Intake chain flange is also advanced 4
crankshaft degrees relative to the MTX cam. As the Intake chain flange is what drives the Exhaust cam, this
effectively advances the Exhaust cam in an engine with ATX cams by 4 crankshaft
degrees, which also reduces the overlap by 4 crankshaft degrees. Compounded with less duration on the ATX
intake lobe, there is substantially less overlap with the stock ATX cams. In total, there is 6 crankshaft degrees less
overlap, 4° due to the advanced exhaust cam, and 2° due to 4° less intake
duration (1/2 of the total duration difference). Note that if you are regrinding cams, it is critical that both
intake cams be either MTX or ATX, or you will have mis-matched exhaust lobe
centerlines between banks due to the 4° difference between MTX and ATX exhaust
cam timing, as driven by the intake cam flanges. We carefully check each set of camshafts to verify that we have
matching intake cams for each set of cams made.
To make our Plus 40 cams, we take MTX cores,
add a 0.055” lash cap, and grind a new profile ‘straight up’ (i.e. same centerline
as stock) which includes grinding the base circle approximately 0.055” and
broadening the tip to increase the lift and increase the duration. In addition, quieting ramps are incorporated
into our lobe profile to keep the valve train quiet and lessen the shock on the
valve springs that you would otherwise get with extreme ramp rates. Quieting ramps are a new feature for SHO
Performance cams. Since the tip is
broadened, it is impossible to get all 0.055” as additional lift, since the
stock lobe is quite pointy, and we need to account for wear etc. It is also not practical to grind more off
the base circle – we are nearly into the shaft of the cam as it is, and
clearancing of the cam journals is required to get this far (so the shims won’t
hit the cam journals, since they are now 0.055” closer to the shaft of the cam,
and would otherwise hit the cam journals if the journals were not clearanced
properly, keeping the valves open – a bad thing).
To make our Tri-Flow cams, we take MTX cores, add
a 0.055” lash cap, and grind a new profile which includes grinding the base
circle approximately 0.055” and broadening the tip to increase the lift and
increase the duration. For the ‘secondary’
lobe, which is mated the short fat runner that is only open over ~4000 RPM, we
grind the same high lift/high duration ‘straight up’ lobe as our Plus 40 cam. For the ‘primary’ lobe, which is mated to
the long skinny runner that is open all the time, we grind a lobe that is lower
in lift and duration than the secondary lobe, and is retarded relative to the ‘straight
up’ secondary lobe, to decrease overlap when only the primary runner is being
used before ~4000 RPM. The amount of
primary lobe retardation is such that the intake valves close at the same time. The idea is that when the secondaries are
closed below ~4000 RPM, you have less overlap, intake lift and duration than
when the secondaries are open above ~4000 RPM, and the runner to the larger
lobe is no longer blocked. This mimics
the effect of variable valve timing and lift without the usual hardware involved. Increased lift, duration and overlap is
generally detrimental to low RPM operation, and advantageous to high RPM
operation. Granted, there is an
incomplete separation between primary and secondary intake ports in the head, so
some cross-over may occur in the head, but the idea is that the direct air path
is controlled by the secondary throttle plates to keep the effect of the large
lobe in RPM ranges above ~4000 RPM when both runners are in use. Thus a Tri-Flow cam should have a smoother
idle and more low end power than a Plus 40, while loosing little to the Plus 40
in the top end, when the long skinny runner is essentially a cork, and not
flowing much air flow relative to the short fat runner, and thus the lower
lift/duration lobe in the lower-flowing skinny runner is not much of a penalty. Colt Cams discusses the Tri-Flow technology in
general here
but the setup for the SHO is somewhat unique, as a different runner is used for
the ‘primary’ and ‘secondary’ lobes, instead of the usual use of identical
runners in other engines for both lobes.
Their use of ‘primary’ (large lobe) and ‘secondary’ (small lobe) is also
reversed relative to the normal SHO usage of the ‘primary’ as the low RPM runner
which uses the smaller lobe in our application, and the ‘secondary’ as the as
the high RPM runner which uses the larger lobe in our application. Thus the swirl effect may not be the same in
the SHO application.
To make our Plus 20 cams, we take ATX cores,
and as with the MTX cores, we add a 0.055” lash cap, and grind a new profile ‘straight
up’ (i.e. same centerline as stock) which includes grinding the base circle
approximately 0.055” and broadening the tip to increase the lift and increase
the duration. Since the ATX intake
cores have less lift to work with compared to MTX intake cores, even though we
are grinding 0.055” off the base circle, we can only get about 0.020” more lift
than a stock MTX intake cam, hence the ‘Plus 20’ name. Compared to a stock ATX intake cam, the
increase is just as dramatic as it is for an MTX intake cam, (going from a
stock ATX cam to a Plus 20 is approximately a 0.040” increase in lift), but for
our purposes, we will compare all cams to stock MTX cams when quoting increases
in lift etc.
Since the same exhaust cam is used for both MTX
and ATX engines, the core is the same, and thus our exhaust cam spec is the
same for Plus 40, Plus 20, and Tri-Flow Cams, i.e. approximately a 0.040”
increase in lift. In other words, the
‘Plus 40’ exhaust cam is used for the Plus 40, Plus 20 and Tri-Flow cams. Thus the Plus 20 is really a Plus 20 intake /
Plus 40 exhaust mix.
To make our Plus 10 cams, we take MTX cores,
add a 0.035” lash cap, and grind a new profile ‘straight up’ (i.e. same centerline
as stock) which includes grinding the base circle approximately 0.035” and
broadening the tip to increase the lift and increase the duration. As with the first two grinds, quieting ramps
are incorporated into our lobe profile to keep the valve train quiet and lessen
the shock on the valve springs that you would otherwise get with high ramp
rates. Since the tip is broadened, it is impossible to get all 0.035” as
additional lift, since the stock lobe is quite pointy, and we need to account
for wear etc. Clearancing of the cam
journals is not required with the Plus 10 cam.
Here are the specs of the five cam offerings
(the fifth is a combination of two grinds) – these are ‘actual’ numbers and not
some inflated ‘advertised’ number:
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SHO NUT Performance Tri-Flow Cams |
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Specifications |
Compare to Stock MTX: |
Increase from Stock: |
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Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Overlap* |
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Secondary Int. |
0.390 |
228° |
0.348 |
205° |
0.042 |
23° |
24.5° (S) 9.5° (P) |
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Primary Int. |
0.375 |
218° |
0.348 |
205° |
0.027 |
13° |
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Exhaust |
0.365 |
227° |
0.328 |
201° |
0.037 |
26° |
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* Can be
increased or decreased 6 or 12 degrees with our adjustable camshaft sprockets |
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All
degree measurements are in crankshaft degrees. Divide by 2 for camshaft degrees. |
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SHO NUT Performance Plus 40 Cams |
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Specifications |
Compare to Stock MTX: |
Increase from Stock: |
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Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Overlap* |
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Intake |
0.390 |
228° |
0.348 |
205° |
0.042 |
23° |
24.5° |
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Exhaust |
0.365 |
227° |
0.328 |
201° |
0.037 |
26° |
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SHO NUT Performance Plus 20 Cams |
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Specifications |
Compare to Stock MTX: |
Increase from Stock: |
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Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Overlap* |
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Intake |
0.365 |
227° |
0.348 |
205° |
0.017 |
22° |
20° |
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Exhaust |
0.365 |
227° |
0.328 |
201° |
0.037 |
26° |
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SHO NUT Performance Plus 10 Cams |
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Specifications |
Compare to Stock MTX: |
Increase from Stock: |
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Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Overlap* |
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Intake |
0.370 |
214° |
0.348 |
205° |
0.022 |
9° |
11° |
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Exhaust |
0.345 |
214° |
0.328 |
201° |
0.017 |
13° |
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SHO NUT Performance Plus 10 intake - Plus
40 exhaust Cam Mix |
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Specifications |
Compare to Stock MTX: |
Increase from Stock: |
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Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Lift |
Duration @ 0.050 |
Overlap* |
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Intake |
0.370 |
214° |
0.348 |
205° |
0.022 |
9° |
18° |
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Exhaust |
0.365 |
227° |
0.328 |
201° |
0.037 |
26° |
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The Tri-Flow cam is targeted at someone who
wants to reduce the negative effects of a ‘big cam’ at low RPM, while retaining
the ‘big cam’ effect at high RPM. Of course, both cam timing and overlap can be
independently adjusted with our SHO NUT Performance Adjustable Cam Sprockets.
The Plus 40 cam is targeted at someone who
wants maximum top end power in a motor with ported heads and dramatically
increased displacement, i.e. stroker or big-bore motor that is used for high
RPM road racing. The Plus 40 cam may
not produce any more power than the Plus 20 when put in a 3.0L or 3.2L with
stock heads, but may have a rougher idle due to the increased overlap. Of
course, both cam timing and overlap can be independently adjusted with our SHO
NUT Performance Adjustable Cam Sprockets.
The Plus 20 cam is targeted at modified cars with
stock heads and a 3.0L or 3.2L. Note
that the 4° exhaust cam advance/overlap reduction (compared to an MTX cam set)
in the ATX core is carried through to the Plus 20 cam, and thus the Plus 20 cam
set will have 4.5° less overlap than the Plus 40 cam, while retaining the Plus
40 exhaust profile. As before, both cam
timing and overlap can be independently adjusted with our SHO NUT Performance
Adjustable Cam Sprockets.
The Plus 10 cam is targeted at a stock or
near-stock motor, and should have more low end torque than the other two
numbered cams, by virtue of reduced lift and duration and overlap, and thus
boosting power all the way through the power band, compared to stock. As before, both cam timing and overlap can
be independently adjusted with our SHO NUT Performance Adjustable Cam
Sprockets.
The Plus 10 intake – Plus 40 exhaust cam mix is
targeted at a forced induction car that needs minimum overlap and maximum
exhaust lift and duration. Both the
Plus 20 and the Plus 10/40 mix give minimum overlap and maximum exhaust lift
and duration, but the Plus 20 (actually the Plus 20 intake – Plus 40 exhaust
mix as noted above) does it by advancing the (plus 40) exhaust cam and keeping
lots of intake duration, while the Plus 10/40 mix does it by reducing the
intake duration while keeping the exhaust timing stock. As before, both cam timing and overlap can
be independently adjusted with our SHO NUT Performance Adjustable Cam
Sprockets.
Pricing, including
lash caps and a shim rental and excluding core charges/refunds is $700 net for
any set of numbered cams (Plus 40/20/10) and $750 net for the Tri-Flow cam. Shipping/handling is extra, and is $45. This is waived if you pick up the cams at
Colt Cams.
The shim selection
for the rental is selected knowing that since these are ‘unworn’ lobes, the
required shims will be a few sizes thinner than we usually supply for worn
stock cams. If you know the shim sizes
in your motor, i.e. from your last 60K service, then let us know, and we can
choose the shim selection appropriately.
If you are
rebuilding a set of heads, and can get valves that have a stem that is 0.055”
longer than stock (above the keeper), you do not need lash caps, and
eliminating them from the supply allows the price to be reduced by $100. IOW, Pricing, without lash caps, but with a
shim rental, is $600 net for any set of numbered cams (Plus 40/20/10) and $650
net for the Tri-Flow cams. Shipping is
extra.
Gaskets are
extra. It is recommended that you
purchase an upper gasket set (less head gaskets if you are not removing the
heads) to get all the gaskets you need for a cam change.
The core charge is
$150 for a set of used cams in good shape*, either ATX or MTX, and they MUST
have good bearing journals*. When you
send your core cams in, please advise us if you are sending MTX and ATX
cores**.
* lobe tip wear is
acceptable, since we grind so much off the tip to broaden it. Damaged lobes will be evaluated on a
case-by-case basis. Cam cores with
damaged bearing journals will be rejected.
** as mentioned
before the difference between the ATX and MTX cams are the intake cams. There are various ways of telling the intake
cams apart. Two are:
The core refund is
$150 for either ATX or MTX cores for Tri-Flow, Plus 40, Plus 10, or Plus 10/40
cams, or for ATX cores for Plus 20 cams.
The core refund is $100 for MTX cores if you purchase Plus 20 cams. The reason for the lower refund for the
latter is that we are having a harder time getting ATX cores to make Plus 20
cams, and would like to encourage our Plus 20 cam buyers to provide ATX
cores. Every time someone purchases a
set of Plus 20 cams and sends back a set of MTX cores, we have to come up with
a set of ATX cores to make their Plus 20 cams, and end up with an extra set of
MTX cores left on the shelf. Over time,
our pile of MTX cores has grown to the point that we really don’t need any
more. In fact, it is NOT required to
send in cores at all, if you wish to simply pay the core charge outright and
keep your own stock cams.
If you can send cams
ahead of time, or have your own shims, you avoid the core charges, though a $50
charge will be added for someone sending in MTX cores ahead of time for Plus 20
cams. All cores are returned to:
COLT CAMS
#54 - 3347 262nd
Street
Langley, BC, V4W 3V9
Canada
TEL: (604) 856-3571
IMPORTANT!! – It is
VERY important that you write ‘Damaged camshafts for repair and return, value
less than $10’ on the package and the customs slip when you send it out. You are welcome to insure it for more, but
make sure that no value shown on the box or paperwork attached to the box is
more than $10. This is critical to
ensure that the package gets through Customs without any problems. If you do not include the above wording on
the box, we will adjust the core return by any customs/brokerage charges paid
to receive the cores. If you are
checking shipping costs, a set of cams weighs about 20 lb. If you use USPS, USPS air parcel is ~$35
with $100 insurance and takes 4-10 days.
USPS ground parcel is ~$25 with $100 insurance, and takes 4-6 weeks.
IMPORTANT!! – be
sure to remove the cam gears and the shutter wheel on the end of the one
exhaust cam before you package them! If
you leave them installed, the cam gears will invariably rub on the cam journals
and damage them. Cams with damaged
journals will NOT be accepted as cores!
Cams