- The Clubsprint class at World Time Attack is actually one of the more competitive with a
very limited number of modifications that can be made to the car.
And we're here with Jamal Assad's Evo 6 RS which is the reigning clubsprint championship winning
car from 2019, the last time World Time Attack ran and we're going to have a chat with
Ben from Benchmark Solutions about some of the changes that have been made to the car.
Ben so far the car as I understand it, has run about, is it 2 seconds a lap quicker than it did
back in 2019?
- Yeah so between 2 and 3 seconds from 2019.
We're down to a 33.7 as of this morning.
- Now despite the fact that the car's that much quicker, from what you've told me off
camera, it's actually making quite a bit less power which would on face value seem pretty
counter intuitive so can we have a quick rundown on some of the key elements that you've changed
since 2019?
- Yeah so before 2019, everything was massive, big power, big piping, bit turbo, everything.
2019, we brought everything down a size and found great gains everywhere.
2021, and through Aus Time Attack in the last few years of testing, we've gone down to a
smaller turbo kit again, little bit more serviceable and we've found that we were probably, we felt
like we were overpowering the chassis so we pulled around 100 kW out of it now.
- So is this, you've said overpowering the chassis, you're talking about basically you were making
more power than the car could put to the track or is it more a case of getting a powerband
that's more usable?
- Yeah probably both, we knew that we had large areas to gain in braking, diff control,
chassis management, things like that and really putting power into it anymore was, we were going
either the same or going backwards.
- And I think it's really important for people who are just looking at power figures to understand that
tractability, particularly out of low speed corners where you're maybe lower in the RPM,
if you're off boost there and it takes a second to get back into the boost curve, that's a lot of
time that you're actually losing and you repeat that a couple or three times around
a track and it's a big difference so you've said you've gone down again in turbo size so can
you tell us what you're running at the moment?
- Yeah so we're now running a Garrett G30770 in the newer release G series.
Now fitted to an R Tech cast manifold.
So it's a lot more serviceable, similar mid range and low end but a lot flatter power
and torque curve now.
- You mentioned serviceability a couple of times so can you just elaborate on what you're actually
referring to around that with that R Tech investment cast manifold?
- Yeah so normally with your bigger tubular manifolds, they look really nice, they perform
well, however the way the runners typically ran for sizing and power band, they don't
allow you to get tools on them, they don't allow you for quick changes, quick repairs
things like that to turn around session to session so after, we had a turbo failure a
few years ago and it became blatantly obvious that we couldn't turn the car around.
The car was not damaged but we couldn't get the car apart and back on and it took
two sessions to do that so that was where a fundamental change in how the car was
built was looked at to make sure that this kind of stuff doesn't happen again.
- Yeah I do often wonder to myself as I'm getting in there with the ring spanner and
I'm doing a 16th of a turn at a time, I'm wondering if the guy whoever designed this
manifold actually ever had to install or remove one so it's an easy thing to overlook
there and you can see with the design there, everything is nice and accessible and V band
as well for the turbo and wastegate.
- Yeah so no gaskets was the main thing, no studs, basically no, less points of failure.
Our wastegate's easily accessible, dump tube's accessible, both turbo in and out are accessible
and all the lines in and out of the wastegate and turbo are accessible.
- So OK other than the turbo which we've covered now, what else have you changed
on the package?
- So once we found the turbo was where it needed to be, we then looked at other
possible areas, so the next one to be identified was the camshaft package.
This car has come to me with an existing package.
It was running a HKS older cam grind, 272, 278 split, really good for a street car
but not in the powerband that we're operating in.
So we went to our tried and tested cam from American GSC, they call it an S274.
Picked up what we thought it would, no loss of spool and torque after optimising the variable
cam and then 25 to 30 kW gains at about 50 to 80 newton metres throughout the rev range.
- That's a significant improvement, you've just mentioned variable cam so just to clarify,
this is an Evo 9 engine or cylinder head fitted to the Evo 6 so variable cam control on the inlet
cam and I assume from what you've just said, optimising that and swinging that cam through
the rev range is critical?
- Yeah that's right so pretty much as far as it'll go reliably on initial ramp up and then
just calibrate it on the dyno to find where the sweet spot of airflow through the cam
vs RPM on the engine.
What we did find ironically that the camshaft now flows so much, it's taken a lot bigger
toll on the turbine wheel and housing regards to manifold pressure in the exhaust.
We're actually making a little bit less right up the top just due to the engine efficiency
but everywhere else is so much larger in power and torque.
- Overall the area under the usable power band is an improvement.
And another big change is in the braking department so talk us through that.
- Yeah so we work closely with a company called 909 Motorsport which are a distributor
of Bosch ABS units so this has now got fitted an M5 Clubsport package.
It's pretty mind boggling.
The braking now, it's the same stuff that's on GT3 cars and stuff so that was a big big big
step forward in braking.
- Previously the Evo 6 comes out with a factory ABS system, were you previously running
that ABS or was it not up to the task?
- So the RS' are optioned ABS or non.
This one had no ABS so we ran it the first few years with no ABS.
The driver Jamal was doing quite well, we weren't really pinching tyres too much and
things like that but we were just finding there was less and less large portions to grab at
for time to be gained so yeah the ABS was a big big game changer in my opinion
especially if the weather's inclement then it's even better.
- I mean definitely if you're not a professional driver as well and you're out on a wet track
then yeah the consistency and driver confidence that comes through in knowing that you're not
going to lock a wheel when you hit the brakes I think it's worthwhile definitely.
Alright so another aspect that I'm really interested in diving into is your centre diff control because
as with a lot of these 4WD cars, the Evo has an adjustable centre diff so essentially you've got
the ability to control the torque split front to rear within certain realms so can you talk
to us about how you're doing that and how critical that is to lap times.
- Yeah so this car runs as we've said before a MoTeC M1 with a custom package from NA Autosport
in Queensland.
Nick Ashwin who wrote the package has had a lot to do with bringing the diff control up to the
last stage of where it's at now.
We initially ran it but the success wasn't as good as what we'd felt so Nick's come
onboard, sorted out all the dramas and really worked in refining the last little bit
and piece but now the diff control's completely refined regarding pressure in and out of braking
and accelerating, steering angle and G and yaw and everything is factored into that as well but it
basically just controls the lock and unlocking of the diff just to give good drive out of the corners,
no wheel spin out of the corners, a lot more stability on braking but overall, chassis balance
to the driver is a big gain from the diff.
- What are you using as input in order to go in a certain direction with the diff control,
is this based on data input or are you basing it on driver feedback or is it a
combination of all of the above?
- It's a combination of both.
We thought we had the diff control quite good but then the driver feedback was
telling us otherwise even though it wasn't always shown in the data so I'm going back to using the
driver is the most important because he's actually steering the car and then if he's
finding that it's say wheel spinning or it's pushing or that kind of feel, sometimes you
don't always see that when you're looking through your traces so we've found that using
that and refining the way the diff's locking and unlocking, sometimes too much lock on
corner exit, I'll tend to push, just using that kind of approach so it's a balanced approach
between both.
- When you're talking about a handling balance for a car, obviously there's different elements
that can influence the handling balance between understeer or push and oversteer or the car being
loose, part of that of course is the diff control and how you're doing that but of course the
actual suspension setup, anti roll bars, spring rates etc, also influence that so how do you
decide whether you're going to change the mechanical package in terms of spring rates,
anti roll bars etc vs trying to fix that in the diff control or can you kind of overcome some
potential handling imbalance in the chassis with the diff control?
- So you can only correct so much of one area with a mechanical issue until you start chasing
your tail in my experience.
So this car also this year has shock pots fitted.
Sorry I forgot to mention that, made a humongous difference in suspension setup.
So ERS work with a company in Sydney called DNA Autosport, they're primarily chassis,
suspension and driver tuning.
So they revalved all the shocks after taking data from the shock pots and then have
worked closely to make suspension changes.
So we made no diff changes at all until we felt the suspension was where it needed to be,
sorry they felt the suspension was where it needed to be.
The driver was confident in the suspension, confident in the braking, confident in all the
other areas.
And then we kind of have brought the diff control in to refine the overall, rather than
changing too many things we're probably guilty of in the past and you're not sure if
one does the other and so the two or three years off has been a bit of a blessing in that
way because you can have one side of the car sorted and then let's pull all the power
out of it and step forward in each area and then go from there.
- Yeah I mean essentially it makes sense, try not to put a bandaid over a mechanical
setup fault.
- Yeah exactly.
- Well look it's been great to get some insight into the car Ben and I mean just another shining
example of where power is not the be all and end all, sometimes less can in fact
be more, the time that you've managed to get out of this lap time around here in the two
years since last World Time Attack is certainly impressive so we wish you all the best for the
rest of the weekend, thanks.
- No worries, thank you, cheers.
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