- While the rotary engine has long been a fan favourite, there's no denying that they
aren't known for their reliability.
Now we're here with Aaron Parker, his FD RX-7 behind me is a competitive drift car.
Aaron's also well known for his role in the Netflix Hyperdrive series.
However Aaron's also a talented mechanic, working for a Formula D Pro 1 team.
We're here to find out a little bit more about how he's managed to keep such great
reliability out of his 13B.
So for a start Aaron, in terms of that reliability, obviously it's going to depend
on the use, drifting is brutal on just about any engine.
Also depends on the amount of power you're producing so let's start there, how much power
is this 13B producing?
- So the car makes 510 wheel and 420 torque.
- And what sort of boost pressure are you using to get that power level?
- U.S. would be, we use psi, about 19 psi.
- OK so it's not really being pushed very hard.
- Not too bad, it's all about efficiency.
As much as you can, make the motor do less work.
- And what sort of fuel do you get to run it on?
- Ethanol, so I'm using pump, I tune it on street pump ethanol or E85,
but whenever I can I'll use Ignite 114, it's just a higher octane ethanol blend.
- Alright so what do you need to do to a 13B out of an FD RX-7 if you want a
reliable 500 plus wheel horsepower?
- You know as difficult as it sounds, it's really not, you just need to make sure that
the maintenance, you're upkeeping on, you've got to have good plugs,
you've got to have really good oil, you need to make sure that it stays cool which
drifting is not going to do that to a car but I guess you just really need to make
sure that the maintenance is upkept all the time and that things are right
from the beginning.
You start patching things and it's just never going to work.
- Now in terms of the internal components, this is an area where there's a huge variation
between what we do in the piston tuning world, or piston engine building world
and the rotary engine building world.
Obviously we've got a huge range of aftermarket components in terms of
piston engines, not so much in terms of the internal components of the rotary
engine so what have you got there, are you still running relatively stock
internals?
- Yes so it's Mazda rotors, all series six.
A lot of people mix those things up, we've just kept with the S6 block.
The only thing that is aftermarket in there is my apex seals which are going to be PTS seals.
- Alright so that's one of the key areas we see a lot of failures with rotary engines
is broken apex seals.
And there's a huge amount of debate, argument, misunderstanding,
misinformation about the factory Mazda seals versus the aftermarket seals
and then even when we get into the aftermarket seal world, there's a huge
range of options.
Everyone has their favourites, the pros and cons, so can you tell us why it's necessary
to go from the stock Mazda seal to the PTS?
- Yeah well the Mazda factory seals are actually pretty good but in this case,
we're not doing the same thing as Mazda intended, which is drifting, you have a start,
stop, these cars see no cooling, there's no cool down laps or anything like that.
So we pretty much premix just to try to help with wear characteristics of the apex which
is ultimately the failure point at the end.
So if you've got a good motor, it's not just going to blow up and your apex seals
are not going to fail, it's just going to slowly slowly lose compression.
- Alright so there's a bit of information in there that I want to dive into.
I definitely want to talk about that premix versus using the Mazda oil pump for
adding that oil in but before we get into that, do you know what the material of the
PTS seals are?
- I do not, I do not know.
- 'Cause this is one area that I do know there are some pros and cons,
obviously the factory Mazda seals don't wear the rotor housings.
Some of the aftermarket seals, and I'm not speaking for PTS specifically here,
are known to be incredibly strong and they break with detonation.
However they will wear the hell out of your rotor housing so there's some
balancing that you need to do there.
- I think we have the best wear characteristics out of this seal, I'm not saying it's right for
every application but for us this seal works perfect, doesn't wear the housings too
much but at the same time you don't want to lose compression from the get go
'cause then the motor's not going to last long.
- OK so you talked about the pre mix.
So in stock form you've got the stepper motor controlled oil pump that basically
injects oil from the sump into the engine for lubrication purposes.
And it's pretty common with aftermarket built engines to ditch that and go to a
premix where that oil, two stroke oil is added into your fuel tank.
So can you tell us where the advantages in that premix lie?
- Yeah so pretty much, it's actually compression, so that actually does help
wear characteristics on the rotor housings.
Again, with no start or cooling with these runs and stuff like that, you really need
to make sure that you're having proper lubrication throughout your run.
We premix pretty heavy, it's like 2 oz to a gallon (64:1) ratio.
Yeah and literally just dump it in there and it's really helped this motor last
a very long time.
I know that there's misunderstanding and everything about mixing ratios and this
and that but you also remember the type of fuel you're using, I'm using ethanol,
it's kind of like a detergent so you need to make sure that you're almost
over lubricating the motor to make sure that everything's happy.
- So a couple of things I want to talk about there just to elaborate on what you're
saying as well.
One of the advantages with that premix is you're getting a better disttribution of
the oil across the entire rotor, the apex seal versus the factory injection system,
injects it essentially right on the centre of the apex seal.
So there's some rotary engine builders think that that's a really important aspect of the
premix but then just to talk about your premix ratio, so 2 oz to 1 gallon is massive and
of course as we add oil into the fuel, that kind of reduces the effective octane
rating so is that a concern for you when you're considering your premix?
- I think it would be if I was on maybe a gasoline mix.
Ethanol's much more lenient in terms of where the air/fuel is going to be and I
think the motor just being two stroke kind of only helps that if that makes sense.
- Yeah I guess the other thing that we really need to come back to is you're
really not pushing this engine that hard in terms of power and also the boost pressure
so there's probably a lot more leniency there than if you were running at 35 psi
of boost.
Now the intake system on the engine, this is kind of the area where huge amounts
of power can be gained with the rotary engine with porting options, there's extend ports,
there's bridge ports, peripheral ports, et cetera, the list goes on.
Everyone's got their own take on what's superior, can you tell us what you're
running here?
- Yeah so I've got a semi peripheral port, it's two small about inch holes in each
rotor housing along with street ported, I don't know what you guys would call
it over there.
- Extend port maybe?
- Extend port yeah on the side ports and big exhaust ports and pretty much
we're just trying to utilise or get as much air into the motor as possible with two
additional ports on the rotor housing.
You, well I guess I'll go into application, I did it for response.
Response down low and everything, I want the motor to make as much power
in the mid under the curve as possible, I'm not so much worried about the power
up on top.
And this port combination kind of gave that to me.
- So if you were chasing very high RPM power, the holy grail has always been the full
peripheral port but with a peripheral port, a large peripheral port, you're going to
destroy that bottom end.
So this is kind of giving you essentially best of both worlds?
- Yeah because I mean you go full peripheral port, nothing against them but drivability
becomes a concern, low RPM stuff and in drift let's say you're off throttle in
a corner or something like that, revs drop, trying to get back into the power range,
just puts you at a disadvantage.
Whereas a guy with like, let's say like a blown V8 or something, he's got
twice torque and twice the horsepower at three grand and you're not even
making anything.
- At the end of the day, you do still have a small capacity engine so you've got to
make everything work properly for response.
Now on that note, and I do know that you're not running it at the moment but we do see
that the car is also set up with a nitrous system.
So can you talk to us about that and how you intend to use it?
- So I'm pretty much using nitrous to fill in the gaps of having a small displacement
engine in the first place.
It's going to be set up on the TPS and throttle parameters so that full 100%
throttle, or 80% throttle, only between 3000 - 4000 so a window of nitrous
operation just to help the turbo get online so that it can do its thing for
the rest of the powerband.
- So you're essentially using it as a form of anti-lag?
- Yeah low end boost.
- Get that instant response.
- Yeah to make up a hole for torque that, what are they called?
- Yeah no understood, getting that turbo up on boost, so filling in that hole in
the low RPM.
In terms of that turbo, we haven't actually talked about what you're running there
so can you fill us in there?
- Yeah so it's a BorgWarner 8474.
I came from the 8374, both are awesome turbos and I went slightly larger because I
planned to use nitrous now to kind of make up I guess the window that I'd be losing
in response.
- Now that's interesting, the 8474 is a relatively new turbo from the BorgWarner
lineup and we've actually got one ourselves, unfortunately it hasn't been on the dyno yet.
And this is an area where there's very scarce information on the comparison
between the 8374 and the 8474.
Given that you've got first hand experience, can you tell us for the same amount of boost,
are you making more power with the 8474?
- So technically slightly less.
So it's one horsepower but again this motor's three years old.
I would say that the 8474's more efficient but I don't know if I'm running a high
enough boost pressure to really utilise its, you know.
- Yeah probably 19 psi, you're kind of only really just getting into it.
- Yeah with the new motor I'll probably raise the boost a little more, get into that
and it'll be a better comparison but I couldn't say for sure.
I will say the drivability I noticed immediately but that's just because I'm
pretty in tune with what's going on.
I lost a hair of response, I don't think it really mattered so much, I just noticed it.
But again once I turn nitrous on, that could be a whole different ball game.
- Look Aaron it's been great to get some insight into the car, look forward to tracking
your progress next year as you enter the Formula D Pro 2 ranks.
I wish you all the best with a new combination with that nitrous active, thanks for the chat.
- Thanks man have a good one.
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