- While there's no doubt that the pro and open class cars here at World Time Attack
Challenge are exciting to watch, the problem with these cars is that the amount of money
that needs to be poured into them makes them completely unrelatable to a lot of home
enthusiasts.
Now we're here with Benjamin from Benchmark Solutions with the ERS Mitsubishi Evo
running in the club sprint class.
Now this club spring class is a very competitive class, very limited on the
sort of modifications that can be made and this means that the cars that are
racing are a lot more like what you'd expect to see out on the street or at your local
club level race meets.
So for a start we've already covered this car last year Benjamin, I want to cover some
of the changes that have been made to it but before that, it's probably important to
mention that it's going pretty well here at World Time Attack Challenge, how's it placed
at the moment?
- We're doing really well, heading into the shoot out for club sprint, we're currently
number one.
Just in front of Elusive Racing Integra so it's been a tight battle.
- Two thousandths?
- Yeah about that, it's been back and forth the whole weekend so it's good fun,
keeps us on our toes.
- Alright still shootout to go so you're going to have to stay on your toes.
Now in terms of the changes that you've made, let's just start with the problems
you sort of were facing last year with the car, why did you need to make changes.
- So last year as a lot of you would have seen, we had a fire issue.
The car basically split a turbo gasket and that caused an oil line to rupture,
burnt the front of the car apart.
So it was a rebuild from there but also focused some changes on areas that would
make it more reliable.
- So in terms of getting more reliability out of this, is it a problem?
We do see a lot with turbo gaskets failing, so how do you deal with that,
what have you done?
- So we moved away from anything that could fail, so no gaskets and no studs and nuts.
So it's now V band flanges on the turbo to manifold to dump pipe and to wastegate.
- That makes sense but the problem with that is that it takes you away from the
ability to run a split pulse exhaust housing, you're kind of confined then to a single
entry exhaust housing.
There's a pretty good argument there that the split pulse exhaust housing can give
improved response with the same size turbocharger compared to a single scroll.
So how did that drive your turbo choice?
- OK so last year we were running the 7670 from EFR BorgWarner and whilst producing
great results, at the same time we had a feeling it was choking on the engine with
the RPM required.
So this time we've gone to a Garrett Gen 2 3576 in the 83 rear.
This had little to no losses under the curve before peak boost and then everywhere from
there is gains per pound.
- So essentially very similar boost response, you're seeing peak boost around about the
same area but from there on, more power?
- Yeah so it's about 200 to 250 RPM if you're just measuring pound for pound but the
torque differences are quite close so even though the boost threshold's a little bit later,
the torque delivery, you don't feel it and the extra flow in the turbine side is just another
level.
- And the other thing here we do need to consider is turbo sizing for a circuit car
where the driver knows for any given corner, any part of the track, what gear they're going
to be in, generally you're staying in a higher rev range so I wouldn't say that boost
response is irrelevant but a little bit less of a consideration compared to a street
car where response is so critical is that fair?
- Yeah it is and this track is definitely the largest out of all the tracks this car
races on so boost response is a very big key still because the other tracks further
down south are a lot more focused or tighter corner exists so we were a little
bit concerned how it would affect because this is a once a year event here but the rest
of the events are held on tighter tracks.
But it hasn't been as bad as what we initially thought.
- Alright so in terms of power and boost, what are you actually running, where did
you get to?
- Yeah so on the EFR we're around 380 kw at the wheels, just under 400.
The Garrett we're able to get a bit more out of it so we're at 440 on about 36, 37 pound.
- And is that basically all in, there's nothing left in it?
- Yeah we're out of compressor, the turbine still wants to keep going but the compressor's
all over.
- Is there actually going to be benefits in this class with the limitations on making more
power or does it become a diminishing return there?
- Yeah interesting point, so I've been working with the driver, we actually were pulling
power out of the car, now we rectify the engine issues.
We pulled power back to gate pressure, about 290 to 300 and we were making
suspension and driver changes, focusing on that 'cause we found we were going
backwards, adding more power in.
And once we rectified that and the driver got dialled in, suspension, chassis,
we were at our PB level on 110 kw less boost.
- I think that's a really important point you make that's so easily overlooked.
A lot of people go to the racetrack and try and fix problems with poor lap time
by just adding more power but of course if you've got a car that's not handling right,
add more power and it just makes a bad handling car just even worse which can be
dangerous.
Now you just mentioned some engine issues, so can you talk us through that side of things.
- Yeah so we had, this engine was quite reliable for nearly 18 months, did quite a few track
days, just pushed hard, we suspect we had a cracked head last week on testing and kind
of validated that on Monday, just out of control temperatures and coolant pressures.
So the boys at ERS pulled an all nighter this week and they had a spare 2.3 crate
motor on the stand so we put that in which I think, we talked about running that later
in the year just with extra capacity for the tighter tracks and the different turbo choice.
It's worked really well, the head now is a lot better, it's put together by Mick's
Motorsports again.
Slightly different head package, little bit more compression, little bit more capacity
and the cam size has stepped up to match the inlet manifold.
- Are you still running the MIVEC cam control?
- Yeah variable cam control, with the larger cam though it's really working exceptionally now
to make use of the RPM range.
- With the larger cam, does that actually limit the amount of movement you can use on
the inlet cam or are you still allowed the maximum?
- No so I've pulled it back five degrees just because of the maximum so we've just
basically set a cam limit and I think mid 20 degrees now instead of about 32, 33.
- Alright so in terms of the rest of the system there are well, you've made some changes to
the intercooler plumbing and specifically around the throttle body which is intersting
because I see a lot of debate about throttle body sizing, a lot of people going with
just basically bigger is better.
Not always the way, can you give us your insight on that?
- Yeah so I basically like to size a throttle body off similar to your turbo inducer size
on your compressor.
So the car was running an 82 mm Bosch drive by wire and Hypertune plenum.
A lot of thought around just adjusting the throttle plate angle to effectively reduce
the size of the throttle.
In our experience it doesn't always work and it's not too effective so we actually
have gone down to a 68 mm throttle body, downsized the intercooler piping again to
match down nearly an inch in size.
And yeah so about 300 to 400 RPM of torque gained in the lower end of the rev range.
- So I think most people at 440 kw at the wheels would probably think
on face value, 68 mm throttle body is too small, you don't feel that's restricting
you in power at all?
- No it's actually probably a bit too big.
We would like to have gone out to a 58 to 60 mm but it just wasn't available from Bosch.
Their off the shelf 68 mm is easier to work with, readily available for parts.
It's a good compromise because we think the car will probably end up with a bigger
turbo, we might probably to a G35 when they come out.
- Sounds like a natural progression.
- Talking about the rest of the car there, in terms of the transmission, what are
you running?
- Runs and Albins H pattern dog engagement.
- So you're limited in the club sprint class to non sequential gearboxes?
- Yeah that's correct so it's got to stay H pattern gearbox.
This year we've added a Hollinger HGK-H flat shift knob.
So that's running through the MoTeC M150 and flat upshift changes, driver can just keep
it pinned and just grab gears.
- Little bit more challenging with the H pattern shift pattern though with those
flat shifts because if you get it wrong, you can end up going straight from the top
of let's say fourth gear, back down into the wrong gear, not really a good look.
- Yeah it's interesting, on the dyno there's always a bit of a pucker moment the first
few times you grab the gears and testing on the roads, it's interesting, you've got
to commit with the H pattern and you've just got to just send it to the next gear.
You try not to do it with a customer next to you basically.
- Now in terms of the rest of the transmission there, you've also got a controllable centre
diff, active centre diff and I just want to get some insight into how are you using
that with the MoTeC ECU in terms of controlling it and where the benefits are?
- Yeah so the ECU takes all the chassis inputs, so we've got four wheel speeds, steering
angle, your normal brake and throttle and some G inputs.
It then uses that to determine clamp load based on acceleration and braking
and steering angle and then the driver has, on the keypad a multi position driver switch,
so he can run up to nine different diff maps.
We usually use two to three around the track depending on how he's feeling and the track
conditions but yeah it's actually really effective, it works exceptionally, it's been
one of the biggest changes, once we've dialled that in nicely to us
consistently running good times.
- In terms of the electronics side of that, are you running a separate diff controller
or are you integrating this with the ECU?
- No it's all integrated in the M150, it handles everything.
- So that's the MoTeC M150, just for those who are following along?
- Yeah so MoTeC M150, it runs a custom firmware from an Australian company,
everything's all in house, the dash is just display, everything's through the ECU.
- So again just for those who kind of really aren't familiar with the M150,
it's quite unique in that really you can buy it from MoTeC with off the shelf firmware
to run most things and then you've also got the ability to buy custom firmware or write
your own custom firmware to do what you want and that's what you're talking about here.
So this isn't something that is available from MoTeC, this is a third party firmware package?
- Yeah that's right, so MoTeC have their own MDC diff controller which is really effective.
We just like to have everything in the one house for logability and tunability.
And then we've just found that while most packages cover everything nicely,
for applications like this where you want a little bit control in the central location,
it works exceptionally well.
- Sounds like a great package, look you've got the shoot out coming up, it's great to hear
a little bit more about the car, we wish you all the best and hopefully you can
stay on top, cheers for the chat.
- Thank you.
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