Camshafts

[shimmy]

Who knows much about camshafts!?!?!?!?!?!

I know nothing apart from what the Schrick guy told me on Friday and what i have read on MTorque.

IF i was to upgrade the CSL cams i am led to believe;

1. 280/288 Schick cams with 14mm high lift are best (got the brochure somewhere)
2. change rockers and some other stuff at the same time
3. maybe increased wear
4. get bespoke map
5. 15-20 bhp gain above 5k revs mainly
6. loss low end torque


if anybody has got some NON handbag interesting points to add or links to tell me (i am hoping the NZ boys will stay up all night and trawl the interent for me)

please dont mention the cost yet!!!

[The Gorilla]

Hi,

Couple of small points.

15-20 BHP out of set of cams is not
going to happen.

You may see 8-10 BHP if your
very lucky, real world.

So long as you do not rev past
7900 rpm to often then the
std top end is fine.

Rockers, increased valve springs
to stop valve float etc is more for
constant 8500 rpm, which as your
torque is already falling away on
a std engine then all your doing
is increasing component wear,
not really going any faster.

To do the top end properly your
talking uprated Valve springs,
to stop valve floating at high rpm,
Lighter valve retainers, to reduce mass,
uprated rockers, for constant 8500
rpm, so as the head is off you could
polish up the exhaust ports, triple cut
the valve seats, and so on.

All this on a std engine bottom end
with Higher lift cams would be
about 10-15 BHP pending
what dyno on what day !!!

Change the exhaust manifold,
uprate the Cats or even delete
them and you may get 20 BHP.

Now take your car out on a couple
of hot laps, and now see for
what duration of the lap your engine
is actually spent above 7000
rpm ? and then 7500 ?

All engines have their N/A 'Tuning Wall'
which IMO the S54's is around the
370/375 BHP mark where extracting
more power becomes seriously expensive.

Unless its for Race purposes the money
is better spent elsewhere IMO.

No handbags there, hopefully ?

Regards,

The Gorilla.

[terryb]

Shimmy - I know you're really looking to improve the CSL's performance to match that of a GT3, so why don't you just buy one....

[shimmy]

Originally Posted by terryb

Shimmy - I know you're really looking to improve the CSL's performance to match that of a GT3, so why don't you just buy one....

terryb - im way faster than GT3s already

im after GTRs

[shimmy]

Originally Posted by The Gorilla

Hi,


No handbags there, hopefully ?

Regards,

The Gorilla.

Gorilla

no handbags def and very interesting - i will come back on the cam issue when i have doen some more reading - but i guess the other better value mods you are referign to onn the CSL are cats/exhaust and a remap to get to the 370bhp

[The Gorilla]

Hi,

Shimmy- People always tend to go
for higher lift cams thinking the Car
will be faster.

Higher lift cams in general tend to push
the power further up the Rev band, while
also narrowing down the Camshaft power Band.

A narrowing Power Band is not always
what you want with a 'Road' type
Gearbox.

Once you move the power band further
up, you may find the rev drop / match, from the
gearbox has altered to the point where
you start bouncing off the rev limiter or
are in the wrong gear exiting corners that
previously were not a problem.

The reason this all works for Race cars
with Sequential Gearboxes is their Ratios.

A 6 speed Drenth is usually around 2.7 1st
up to 1.0 direct in sixth.
Thus keeping the engine rev matched to the
close ratio Gearbox is much easier with
higher lift cams and its narrower Power Band.

Do you run the standard rear 3.6 CW/p in your
LSD ?

Change this to a 3.73 if the car still used on the
road frequently or 3.91 if more Track biased.
Have the diff Ramp angle changed to 30/30
for around a 50/75% lock up and you will make
gains in the mid range drivabilty as well as
improve rear end stabilty in / out of the corners.

This would give you far more for the money spent
than a set of Higher lift cams.

Regards,

The Gorilla.

[shimmy]

ive got an uprated 4.10 diff ready to go in (does that work?)

[The Gorilla]

Hi,

Shimmy- Its good for Track work.

Regards,

The Gorilla.

[shane@mbtech]

Originally Posted by shimmy

ive got an uprated 4.10 diff ready to go in (does that work?)

My 4.10 gear kit is in the post, ready for spaaaaaaaaaaaaaaaaa