- Australians have always had a soft spot for the rotary engine and here in Australia,
the rotary drag racing records are fiercely fought over.
Behind me is Steve Barnett's Mazda 6 which currently holds the record as being the
second fastest rotary, or 13b I should say, powered vehicle in Australia.
It's gone as quick as a 6.53 at, is it 213 mile...
- 213 yeah it's done 213 before.
- While rotary engines have no problem making huge amounts of power,
sometimes reliability can be their weak point so we're here with Jon
from John Blanch Engines to find out a little bit more about building a reliable
drag racing rotary engine.
So sorry Jon it's actually Jon Blanch Racing but.
- Jon Blanch Racing, Jon Blanch Engines, same thing.
- Alright so I think one of the things that we've seen over the years is the piston
versus rotary battles, there's a huge amount of aftermarket parts support in the piston
engine world.
And particularly if we look at the top of the import heap, the Toyota 2J, now basically
everyone running five second passes with those engine is running a billet block.
And with rotary engines we just haven't seen so much development in the
aftermarket until maybe the last few years.
And one of the weak points in the rotary engine has always been the plates.
Can you talk us through what those plates actually are and why they fail?
- Well the factory plates were always cast iron and Mazda did a really kick ass job
of designing them for a passenger car, they were never designed to do the kind
of thing that all these race guys are doing with them.
300 horsepower factory engine, guys are pushing these 13bs now up around 1500 and the
plates would handle it but if you had a whoopsie with a tune up, the plates would break
and everything else around it would break and since these billet plates are
available now.
The horsepower that you can reliably make and repeatably make has allowed everybody
to push so much harder and the rotary is now able to compete with a lot of the
piston engines, we've got our billet parts.
We can push the envelope a lot further now with these billet plates.
Now I just want to go back there, you said that the cast plates, as you
mentioned obviously designed around the 300 horsepower engine.
So it's amazing that people even got above 1000 horsepower with these factory parts
anyway.
At the sort of power levels, 1300 plus horsepower, could you actually make that
power with a cast plate at all or are you just running on an absolute razor wire
in terms of how long it would last at that sort of power level?
- Yes you could make the power no problems at all, the billet plates aren't going to make
you any more power.
The advantage of the billet plate is it's more forgiving.
So if the car has a misfire or a bang or you miss your tune up a little bit,
the billet plate can handle the shock and the stress.
Whereas the cast plate would immediately crack and then everything would turn
to shit.
So the billet plate has, it allows you to get more runs, more time to be working with
the engine, it's not a matter of whoops, pull the engine out, we've got to put
another plate in.
Power wise, they're the same, you're not going to magically make another few
hundred horsepower but you will be able to consistently beat on the engine a lot
harder and a lot longer without it having a failure.
- Now I just want to come back to a point where you just touched on there and I think again
for those who are watching, maybe are not familiar with rotary drag racing,
the rotary engine makes huge amounts of power but you tend to have a very narrow
window where the tune up is going to work and be reliable and outside of that window
it's very easy to hurt a rotary engine.
I think probably while a piston engine still you need to be ontop of your tune up,
it's probably fair to say there's a slightly wider safety window with your tune up
on a piston engine versus a rotary, do you think that's reasonable to say?
- Yeah that is exactly right.
On a piston engine, it can have a ping or a rattle and you can hear it and then go
back to the pits and go oh OK we need to take a little bit of timing out and add
a little bit more fuel and you get out of jail.
On a rotary, if you hear it ping or rattle, you may as well go back and
take the engine out because it's already damaged.
So when you're tuning your rotary stuff, you always need to be upon that safe
side and I guess it's a fine line between how close you want to go to that dangerous
edge or how, if you want to stay on the safe side, and that's the difference between
when guys are going fast and not is how far out of the comfort zone they want to go
and how hard they want to push it.
- Yeah unfortunately there's not a lot of world records being set with a conservative tune up
so that's where you really do need to be walking that tightrope and trying to get the most
power out while holding the engine together.
Now talking about those plates there, we have seen, these have come out sort of
in the last few years and seems like at the moment there's a few competing brands
trying to figure out which one works and obviously everyone's got their own take
on it.
So can you talk to us about the particular plates in this engine and how they're
designed?
- The ones I like to use are made here in Sydney by a company called Billet Boss.
I have used a lot of the other ones and the Billet Boss ones are just the ones that I
prefer to use.
I like the way they fit in the engine, their machining process.
I like success wise, quality control wise, everything about the plates I like and
I've had good success with them so to me if it's not broken, I don't need to go messing
with it too much.
Now one of the things with these billet parts is that you've obviously got the side seals
running against the surface of this plate so this brings about a problem.
The factory, a cast iron which is nice and forgiving, that's easy, you can run the seal
against that material, but in this case aluminium, very soft, so you can't run
a seal directly against the aluminium surface so a lot of the billet side plates are coated,
so it's got a hard coating.
Billet Boss have gone a different way with this though, can you talk us through how their
plates work?
- Well the Billet Boss plates have a cast iron insert so a couple of advantages with that.
If you ever stuff up a bearing or the rotor wobbles and the rotor hits the side plate,
you don't need to get the plate ground, you can just replace the insert.
And probably the most important thing for me is with the insert, you can pull the
insert out and it allows them to machine the plate with all the water jackets
in behind it and then the plate sits on down, or the faceplate sits down on top of that
and there's always water circulating in behind that friction area.
So to me, that's one of the main reasons I like to use a plate with the insert because
it keeps the temperature in the engine cool and consistent throughout the whole engine
and you can replace that insert, it's a $500 insert so it's not the end of the world.
On an engine like this where you've got tens of thousands of bucks invested,
if you've got to replace an insert it's no biggie.
- Definitely a lot cheaper than replacing the whole plate.
And getting that cooling flow through those plates, is it safe to assume that a lot of the
other brands maybe don't do that so you've only actually got coolant flowing through
the rotor housings themselves?
- Yeah the other plates do have cooling that goes around the outside but it can't get
in behind the surface area of the plate.
So for me that's an important thing and that's one of the reasons I do like to use the
Billet Boss plates.
- Alright so we've talked about the plates, obviously they're pretty well developed so
far and proving to be pretty reliable.
Another area that is a potential weak point I guess with the rotary engine is the
actual rotors themselves.
This is an area that's interesting, in a piston engine obviously we have aftermarket pistons
from dozens and dozens of manufacturers and in the rotary world it seems that the factory
Mazda rotor is actually still a pretty reliable thing, what can you say to us about those?
- Surprisingly yes the rotors are quite reliable you don't, or very rarely you'll break a rotor.
You can dent them, you can damage them but every time you have an issue, it's always
tuning related or the rotors hit the housing because a bearing is, you've stuffed the
bearing and the rotor wobbles around and touches something.
But in terms of actually breaking a rotor, there's not too many guys that are
breaking rotors so again what Mazda's done with the factory engine is pretty
damn impressive.
It's safe to assume though, you're not taking a factory rotor, straight out of its
packaging from Mazda and slapping it into a 1500 horsepower 13b.
Can you talk us through some of the machining operations or some of the
rework that's required to make that factory rotor work in this sort of applicaton?
- Yeah well the factory rotor comes out of the box, you side clearance it, so no doubt
at higher RPM it's got a little bit of room to move.
I've clearanced the faces as well so again you've got, I'll make the rotor just a touch
smaller so.
- And that's due to the fact that the rotor is actually going to move around,
particularly under the high boost and high RPM?
- Absolutely yeah the high boost, the high RPM, the two step, the revs coming up,
the revs coming down.
Cranks also flex a little bit as well so there's a lot of stuff moving,
clearancing the rotors, essentially you're just making the rotor a little bit smaller
so it's got a little bit more room to do a hula dance in there if it has to.
- Alright so we've talked about the rotor housings, the rotors, the plates there,
one of the key aspects to getting airflow in and out of a rotary engine is the
porting method and there's various schools of though, various techniques from bridge
porting to peripheral porting and in this case you're running a Semi PP.
Can you talk us through what a Semi PP is, what that means and where you see the
advantages?
- Well Semi PP is essentially a peripheral port but it's only a smaller port that goes in the
side of the rotor housing and you retain the side ports at the same time,
a full peripheral port has blocked the side ports up and have one massive big hole.
On a turbo setup, the overlap with that big peripheral port is a little bit too much and
it's very difficult to tune so the Semi PP kind of gives you the best of both worlds.
You're bringing your overlap down but you're also getting that good flow in there.
And in the methanol turbo setups the Semi PP seems to be,
everybody's using that setup and that's the setup that seems to be working the
best so I've spent most of my time working with that setup and it's working and
I ain't going to touch it.
- When you're talking about either a full peripheral port or even a Semi PP,
depending on where abouts you actually place the port through the rotor housing,
it's going to have quite a big affect on the port timing though.
Is there still a lot of secrecy and power and time to be gained in the actual
location of the peripheral port?
Or is it not really that critical?
- With the Semi PP, there's really not that much room to move because you drill
straight through the side of the rotor housing where there's a water jacket.
So most guys with a Semi PP, port timing wise, everybody's roughly in about the
same spot.
Your exhaust port, that is probably, you've got more room to move I guess
with your exhaust port, some guys will port them down lower, some guys will
port them up higher.
Again, you need to port that based on where you want your powerband.
There's not one right or wrong way of doing it.
If the port's bigger, smaller, higher, lower, all that does is have an affect on where
your usable power is going to be.
So you want to match your port with your turbo size, your inlet size, your gear ratios
and get a combination that all works together.
- So safe to say, and understandably so, a huge amount that goes into deciding
on the final spec of the engine and obviously with the second fastest 13b time in Australia
right now and previous holder of the outright record in Australia, this engine's pretty
dialled so thanks for giving us a rundown on what goes into it Jon.
If people want to reach out and find out more about your company, where can they go?
- Probably my Facebook page is the best, Jon Blanch Racing.
Come and check that out on Facebook and any questions or anything just send me
a message.
- Perfect, thanks for your time Jon.
- Thanks for having me guys.
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