- When any new engine is introduced, obviously there's going to be a lot of
people trying to make more power from those engines and there can be a scrabble
at least in the first few months after an engine's released with manufacturers
trying to keep up, manufacturing parts and developing new parts.
Now in terms of getting more power out of the B58 BMW engine that's fitted
to the new A90 Toyota Supra, the cylinder head has a big impact on the power and
performance of the engine and the camshaft grind is a key aspect of the airflow through
the cylinder head.
We're here with Kyle from Kelford Cams to find out a little bit more about their
brand new cams for this platform.
So Kyle obviously the A90 Supra's pretty new, we're seeing it being adopted really
quickly all across the world.
It's a no brainer that this is going to become a very popular platform for
enthusiasts.
So you've jumped on this obviously pretty quickly with the new cams you've
got here at PRI 2019.
Now I just want to find out for a start, what is the process you go through when
you've got a clean sheet design engine and you're looking at developing a cam,
what do you actually have to do, what's the steps?
- Yeah cool so the first thing we'll do is we'll get the cylinder head, the parts,
the engine and start to reverse engineer and measure the factory, the valve lift
curve so in this particular engine, there is a compound rocker arm system for the
variable valve lift system that's in it so we'll get the cylinder head, we'll set up
our cam measuring software and we'll actually bolt it to the head rather than to
the cam and measure the valve lift curve of the stock cams and then we'll measure
the cams themselves and then the tricky part comes of interpreting the geomtry data
to get those two curves to be the same thing.
- I think a lot of people might think that you just measure the lobe of the cam and
therefore that is your valve life but of course as you mentioned, with a rocker arrangement
and some geometry changes, the lift and duration at the cam lobe doesn't
necessarily reflect what you're getting at the valve and it's what's at the valve that
actually counts.
Now just for those who aren't aware of the B58 engine, the intermediary shaft that
allows the adjustment of valve lift and duration, can you kind of give us the
two second rundown on how that works?
- Yeah sure so it's a, in this engine the exhaust is like a conventional camshaft
on a rocker arm finger follower.
On the intake system there is the same finger follower but rather than the cam
running along that, there is an intermediate rocker shaft that's
controlled by an eccentric shaft that the camshaft then rolls onto that.
So what happens while the engine's operating, the engine's idling, they don't
run the throttle, the valve lift will only be opening the valve a tiny bit.
And then as they advance or move the eccentric shaft, it's changing the rocker
ratio so you're getting lift and duration increasing as it changes the arc that the
intermediate rocker sweeps through.
- So the idea, is the idea here to sort of reduce pumping losses of the engine in
the factory form so you're only really using the valve lift that's necessary for the power
required rather than the throttle needing to be closed?
- Yeah so it's a technology that's been around for a while, we've seen a few diffrent
manufacturers that have run their versions of it.
This seems to be the, one of the more complicated ways of doing it.
But it's a cool little package and we've cracked it which is good.
- Now on top of that, the engine also runs continuously variable cam control system
as well which again nothing particularly new but that's another consideration you
need to take in there?
- Yeah so for our smaller cam grinds, what we've done is we've only really
affected, the way we've shifted the phasing of the cams is we've kept the TDC events
so your intake valve open and exhaust valve closing point's, much the same.
And really added, shifted where the centre lines would be 'cause everything's variable
it's hard to kind of pin it down but we've affected the exhaust valve open and
intake valve closing points so that while the engine's still fresh, there's not a lot
of parts available for it, the piston to valve clearance should be much the same
for having increased performance.
But then of course you can tip it forward and move it.
- So this is a big consideration though for a cam grind for an engine that runs variable
cam control, obviously you can advance and retard the cams, sometimes quite
significantly so do you need to factor that in and basically measure the engine,
the valve to piston clearance with the stock system so you can work out how much
further you can go or at the moment are you just limiting it very close to stock
for safety?
- For the valve events that affect piston to valve clearance, we're sort of keeping
those much the same.
So with the bigger cams that we have done, the B spec, we do our As and Bs, they will,
you'll be able to have the full sweep of factory cam control.
And then we'll get bigger cams that we, we can't take piston valve clearance into
account when we're building a cam, you need that much lift, you need that
much duration, you need to figure out how to fit it in the motor you know.
- Ultimately that's a job for the engine builder to actually check and make sure
that they've got sufficient valve to piston clearance for whatever they're
actually doing.
But at this point I imagine a lot of people are looking for a drop in cam that they
can put in, gain some performance and not have to go and reinvent the wheel,
checking their piston to valve clearance, that confidence that it's there.
So once you've got the factory cam or factory valve motion, basically reverse
engineered, what's the process then, so I'm guessing that there's not a lot of
blank cams available for this engine that you can then grind?
- No, for this one there's nothing available currently, at least that we're aware of.
So with these particular ones, we start with a tall steel bar stock.
We'll rough out the cams that we've drawn, we do a full solid works design of the camshaft
as well, we'll rough mill those out and then we'll go to a heat treating, depending on the
material that we're using, changes whether it's a nitride or a through hardened.
These ones are a K600 tall steel so they're a through hardened material.
We get that done, we get them back to the workshop, we will then straighten them,
'cause generally heat treating bends things and then we'll finish grinding and recheck
straightness and then we'll put that cam into the cylinder head and make sure that
all the numbers that we've done, that's the final check when we're
doing the geometry mapping, we'll actually make little stub shafts with one or two lobes
to check our geometry along the way and make sure that the maths is what
happens in reality because it's not always the case.
So these ones are pretty good now.
- In terms of what you can gain with duration and lift and still keep that variable valve
control, so how much further have you gone, what is the specification in terms of lift
and duration at 50 thou with these cams?
- So these particular ones we've gone up to, let's call it a 280, they're like 280 and 282.
They're around about 236 degrees and 240 degrees at 1 mm valve lift.
We work in valve lift figures rather than 50 thou cam or at the cam because
that's what's happening in the engine.
The engine cares what the valves doing.
And with the lift, because of the arrangement of the rocker arm on the intake system,
we're very finitely limited for how much lift we can add.
So we've only pushed that up from the factory 9.2 mm valve lift up to 9.6, 9.65.
But on the exhaust cam we've gone up to 10.6 mm lift so with what we've seen
in some of the testing, just some really mild cams, we've done a couple of setups
and just done exhaust cam swap outs and nothing else, we've seen 50
horsepower increases just for nothing but a cam swap, everything else, all other
things being equal for the entire power range.
- That's pretty significant when you can gain power everywhere from a cam swap.
- Yeah they lose nothing and they gain everywhere.
And that was a smaller setup than what we've got here so I mean we would
expect at some point you're going to start losing that little bit down low for
the mass up top sort of thing.
- Now when you are upgrading cams, it's not just the cams that you need to
consider, it is the entire valve train and with this comes the valve spring so
what are your considerations there with valve spring, is it possible to run a cam
of this nature on a stock valve spring?
We look at that to start with so for any new product we will actually look at what
the factory springs are capable of, we'll measure them, we'll weigh them,
we'll section them, we'll get frequency numbers of the materials they're made of.
And we'll see if there is something that we can offer that people can just drop straight in,
well on the stock valve train.
Not really lucky enough with the factory spring in this engine to do that so we
then have to look at all the valve train masses, the geometry of them to see
where that mass is going to affect the spring, how it's going to need to be
controlled.
In this one, as complicated as the rocker setup is, a lot of the forces that are in it
that need controlling actually are self cancelling so the spring is not quite
as ridiculous as you might think when you see the big tower of springs and stuff
everywhere so it's been really good, we weigh the valve, we'll weigh the retainer,
in this case we'll replace the retainer with our own design of titanium retainer.
And obviously our own spring designs which we get pack springs over here in
America to make for us, they can make everything we need to a spec we require.
And yeah we'll look at rocker weight, we'll look at moment of inertia of the
travel of all the parts that are reciprocating and moving nad yeah we'll come up with a
spring that is tailored for that setup.
And our cam designs, as we push those parts further and harder.
- Alright it's been great to get some insight into a brand new product and that process
behind it.
Obbviously it is brand new here at PRI, if people want to find out more about this
cam or your other products, how can they get in touch?
- You can get on our website, kelfordcams.com, we have email addresses that you can get
to us through there.
You can jump on Facebook, we're on Messenger as well that we can talk to, we've got a
YouTube channel now that we've just started up, so we're trying to get into
that too.
But yeah or you can do the old fashioned thing and pick up the phone and give us
a ring in New Zealand.
- Perfect alright thanks for the chat there Kyle.
- Thanks very much Andre, cheers.
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