- One of the age old debates when it comes to import drag racing is the 2JZ versus
the RB26 or RB30 these days.
And we've got fans on both sides that are pretty heated about supporting their
particular brand of choice.
Now Bulllet Race Engineering have been making billet aluminium blocks for both
the 2JZ and the RB26 for some time now.
And we're here with Darren from Bullet Race Engineering to talk about a unique
twist that they've just applied to their RB30 block.
So let's get into the elephant in the room here, the 2JZ and the RB26.
And in a subtle way, you've actually kind of combined two aspects into one block,
so can you tell us what you've done here.
- Well we've had a look at the two engines and basically what we've seen is the 2J,
the crankshaft in the 2J we have a seven millimetre larger main journal.
So when you have a look at this in the design of the crankshaft, in the RB crankshaft
with the small main journal we're getting a lot of torsional twist over the length
of the crankshaft which of course takes power away from the back wheels because
it's going into bending the crankshaft.
And so what we thought was how about if we make an RB crankshaft with a bigger
main bearing and as it happens, the 2J main bearing shells would easily fit into an
RB configuration so it was a matter of changing the tunnel size and moving the
main studs to the appropriate location and increasing the material down there
and then designing a crank to suit.
- So let's back up and I can feel the heat building on the internet already,
so let's be really clear, this is not a 2JZ, this is still very much an RB,
you're still using an RB head, essentially it's still an RB30 in terms of the block
architecture and really the part that you've borrowed, stolen from the 2JZ is just
that main bearing journal diameter giving you easy access to an off the shelf bearing
that your customers can then buy and install?
- Yeah correct so it was just, you didn't want to go in and take it to the extreme where
you design a custom bearing which then costs a fortune and then just adds to the
price of the overall project.
- Alright so you've got that seven millimetre bigger journal diameter and am I right in
guessing that that's going to increase the overlap between your main bearing journal
on the crankshaft and your big end journal adding to the rigidity of the crankshaft,
that's what you're talking about with reducing the torsional twist?
It does, it reduces it in that way but in another way we've reduced the overlap,
we still have more than what we will with a 90 millimetre stroke RB crank
but we've gone and used a Honda big end journal and the reason that we've done that
is that's what's being used in the industry at the moment.
But in addition to that, because it's smaller, that allows us to have more material in the
aluminium rod around the rod bolt which is the weakness.
Some people question the rod bolt but if you knew where, how the aluminium was
behaving around the rod bolt, that's where you'd be worried.
So that's given us a lot more material around there.
- OK so it's important to mention there as well, that Honda big end bearing,
that's actually become quite a common choice, a lot of the V8 guys are also running
that shell so it's not an uncommon decision to go that way?
- No and I mean even in the world record engines now in the 2J format,
that's the big end bearing that they're using as well so why not stick with it,
it's not broken so why fix it?
- Now you've mentioned there that one of the drivers with going to that smaller
big end bearing journal diameter is the spacing there with the rod bolts and a
lot of this comes down to the clearance that you've got with the aluminium rod,
it's a very bulky rod compared to a steel rod and you've got clearance considerations
there wherein you're still running what is in V8 terms a relatively small bore diameter,
is that accurate?
- Yeah so because you have a small bore diameter, you're well under a four inch
bore, you have to get the conrod down the bore to assemble the engine so that limits
how wide the conrod can be.
So by reducing the size of the big end pin, that gives us more material because we're
limited on the outside diameter.
- Now one of the issues obviously going to a custom block like this where you've
manipulated the main bearing journal size, the big end journal size is obviously no
longer going to be able to run an off the shelf crankshaft,
so how have you dealt with that?
- So in conjunction with Callies, we designed a crankshaft for this new platform
and sent the design with them with some back and forth with their engineers and then
we've come up with a new crankshaft which is what they call in their ultra billet range
which is their name for that product.
So it's the same as their pro mod cranks or in their V8 range whatever they make.
It's entirely made in the United States and shipped out here.
We've had 15 of them made so we have an engine that will be run for the first time in
a couple of weeks in the U.S. and the whole idea behind this was to get NIssan up there
with the 2J, there's a lot of Nissan guys that are running 2Js because that's the platform
that's evolved and now we have a level playing field and now it's Nissan versus
Toyota in the pro outlaw classes and let's let the guys battle it out and see who
can be the fastest.
- Fair enough, now before I talk a little bit more about the power levels you're
expecting, with that crankshaft, again obviously going to a custom billet
crankshaft, huge amount of flexibility on other design parameters so is there
anything else you've changed in that crankshaft to give an advantage with this
new motor?
- Yeah so one of the other failings with the RB crankshaft was the snout.
The snout is quite small in diameter and it's not as long as what you would like,
meaning that the balancer only really has about 19 millimetres of purchase on the front.
So what we did there was we've increased the diameter by five millimetres which gives
us more wall thickness between the balancer bore and the outside diameter.
And then we've increased the keyway to a 5/16 keyway and then we've increased
the length by another 19 millimetres.
So we've basically doubled the amount of purchase that the balancer has on the end
of the crankshaft and so you could still use the ATI balancer but we have a hub,
so you still use the outer ring but then you use a custom hub.
- And also you mentioned off camera before you've made some changes to the fly wheel
drive flange as well?
- Yeah so we've gone to an eight bolt, we've increased the flywheel flange by
10 millimetres in size and then we've gone from six bolts to eight bolts and we
changed the pitch circle as well.
We didn't run with a 2J pitch circle with the eight bolts because the pitch circle put the
bolts out fairly close to the outside and made the wall thickness a little bit thin.
So we came in a little bit there and we used a 7/16 UNF thread which means that you
can use a small block Chevy, or small block/ big block Chevy flywheel bolt which is just
for ease and there's plenty of that stuff around and it's cheap.
- So a lot of little subtle modifications there aimed at increasing the material thickness,
the wall thickness and obviously changing there to those readily available bolts
as you've just mentioned for the flywheel, so all these subtle things add up to
increased reliability.
At the sort of point these engines are now producing 2500, 3000 wheel horsepower
and potentially above that which is a nice segway, where do you see the limitations
of this block when it's pushed to its maximum?
- Well it's hard to say, the guys at the moment, when you have a look at the
numbers they're running, they must be up at around the 3200 horsepower level.
Talking with some of the teams, they're at 100 psi of boost and they're adding some
nitrous for good measure.
So what's really becoming the limitation now is the cylinder head.
So they effectively, if you have a look at the cylinder heads, the factory cylinder heads,
the amount of CFM that they flow is below what's required for that size engine at the
RPM they're turning.
So once the cylinder head development comes along, which you know we're working
on billet cylinder heads now, so once that comes along and we've sized the cylinder
head and the port size is correct for the engine size and RPM, then I think we'll
see even higher power levels.
- Look it's been interesting to get some insight into that engine and the reason you've
made those changes and we certainly look forward to seeing if the RB guys can
actually take it to the 2J guys and compete on an even footing with this engine,
so thanks for the chat there Darren.
- No worries, thank you.
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