- When it comes to being competitive at Pike's Peak, power and weight are key.
And with 1150 horsepower and just a touch over 1100 kg of weight, this E36 behind me
should be a pretty potent competitor in the open class.
Now we're here with Wayne from Bimmerworld, engineer behind this car to find out a little
bit about what makes it tick.
So first of all Wayne, why the decision to go with the E36 chassis?
In terms of BMW heritage, that's actually now getting to be relatively dated, maybe not in
base form the most aerodynamic selection from the BMW stable.
So what was the driving force there?
- It's just a nostalgic kind of a thing because when BimmerWorld started,
these were the cars that they were selling parts for and it's a favourite among
the BimmerWorld crowd.
Also the older cars are a little smaller too so a little less frontal area but not any
real strategic or performance reasons.
- I guess when you're really starting to build a clean sheet car from the ground up with
no limitations then realistically the body shape doesn't end up being the biggest
factor in the whole build?
- Right and it's a little easier to pick up one of these cost wise.
We spent a lot on the build but the car we started with didn't cost...
- Pretty cost effective base starting point.
Now interestingly though there's not really a lot of BMW E36 left in it.
I want to start with the chassis itself, so you've gone away from a factory style
monocoque chassis, you've gone to a complete tube chassis, so what was the driver behind
that, was that an essential aspect of being competitive in the open class?
- So oddly enough the move to the tube chassis started with the engine.
Originally the car was going to be an inline six which is what these cars
came with so it fits in there nicely.
But we eventually decided to go with the V8 and the V8 sits on top of the frame rails.
- So basically no way of fitting it with a stock chassis?
- Yeah no way to fit it with the frame rails and the struts from the original car.
So once we decided that we were going to have to cut off the frame rails and with
the big tunnels under the car, it just kind of made sense to go to a tube chassis.
We still do have, the body is a real shell, the roof and quarter panels and all
are still a metal shell.
- All still steel components there?
- Yeah but it does sit on top of a tube chassis not just a roll cage.
- OK so you just mentioned that engine which is what I wanted to get into next.
So as you said, these came out stock form with an inline six so you've now got a twin
turbo V8, can you tell us what was that engine sourced from, what is the engine itself?
- So it's the same as the P63 from the GT3 M6.
BMW Races and WeatherTech.
And so that's the race version of the S63 which comes in the M5 and the M6.
- But this base engine actually started life as a GT3 race engine?
- Yes and we, Roush Engines has done a lot of work, I don't know all the things they've
done but yes they've done a lot of internal work.
The GT3 series, they're making around 500 horsepower give or take and we're more
than doubling that so yeah.
- So let's just go back on that because in GT3 form, there is a variety of different
cars running in the GT3 class and to try and get some kind of balance with performance,
one of the key aspects that they have available is the restrictor size.
So that's how the power is restricted down to 500 horse so straight away you
get rid of those restrictors on the inlet, that's going to allow the engine to breathe
and you can make a lot more power.
But of course then the next thing you come up against is the limitations of the factory
turbochargers.
Safe to assume that you've gone to a larger turbo here to make 1100 plus horsepower?
- Yes, I don't know the specs on the turbos but they were sourced from Weistec and
it's a bigger turbo, I don't know all the specs on the turbo.
Roush worked with Weistec on that.
- So in terms of keeping the engine reliable, again at that sort of power level you're
talking double where they are at GT3 where they are well proven and reliable but this
is a completely different ballpark.
- So talking about the rest of that chassis, another key change you've
made here which is quite unique is it's no longer running a gearbox straight off
the back of the engine.
So you've gone to a transaxle, can you tell us a little bit about the decision
behind that transaxle?
- So it helps with the packaging because there's not a lot of room for the driver's
feet and so now we just have a driveshaft going to the back of the engine that gives
us a little more room in the cockpit.
It's also nice for weight distribution.
These cars can have a tendency to have more than 50% on the front axle
so transaxle puts some weight in the back and with this particular transaxle,
the gears are forward of the axle and below the axle which is exactly where you would
want to put the weight if you had a choice.
- Have you got an idea for what the finished weight split front to rear is going to be
now with that transaxle?
- We believe it's going to be really close to 50/50, we have weighed the car a
number of times before it was completed to the point where it is now and it was 50/50.
Now there were a few components missing at that time, we haven't weighed it since
we've completed it but we were under 2500 pounds and right on 50/50 at the time so it
should be really close and if it's not 50/50, we can probably move a couple of things
around and get it there.
- Now the other aspects that's really important to keep an engine like this reliable,
and particularly at Pike's Peak with the high altitude, low air density, you lose a lot of
cooling efficiency so can you talk to us about the cooling package on the engine,
how you've gone through the design of that in terms of both intercoolers as well as
radiators for engine coolant, transmission et cetera?
- So that's something that, so our fabricator, Rich Grut, that's something that he worked
really hard on and there's a cooler in the back of the car, for the gearbox and because there's
not a lot of room in the front, these cars were a little smaller than the 3 series
we have these days so with the V8 and the wide tyres, we're a little crowded for space
up front.
It's got two radiators up front stacked in a V formation like that just to get the surface
area that we need and then in front of each tyre from top to bottom and the width
of the tyre is all intercooler on each side.
And one intercooler for each four cylinders.
- So in an interesting aspect as well, I mean nothing particularly unique for
a lot of European manufacturers but the configuration of that engine actually
has the exhaust manifolds in the valley between the two banks of cylinders and
the inlet manifolds are off to the side.
Conventionally we sort of tend to see that the other way around so does that help
with your packaging in terms of the intercooler setup?
- It worked out, I've never worked with an engine that's laid out like that before.
It worked out nicely, the charge pipes from the turbos come off the top of the engine
and go forward to each corner of the car and then the outlet of the intercoolers is
on the bottom and it just about 12 inches away from the intake manifold.
- Keeps everything nice and short.
- Yeah kept everything nice and short and all the heat is on the top, heat's going to rise
anyway so all the heat's on the top of the motor.
And it worked out really nice.
- Now in terms of the electronics package fitted to the car, that's obviously another key
in order to make the sort of power that you're talking about, obviously boost
control is critical, making sure those turbos are doing exactly what you want.
And then you've got that paddle shifted Hollinger transaxle in the rear to control
the shifting of.
So what's the electronics controlling those and what have you got for a driver display?
- So the ECU is a Bosch Motorsport ECU which we will use for the gearbox as well
and then for the display, it's a MoTeC display.
- So you're using the MoTeC display for logging as well or is that just purely a
driver display?
- For logging also, it's what we've typically used with our IMSA racecars and we're used
to it, we're used to the software, the way it presents data and so yeah.
- Now one of the key challenges with Pike's Peak is the altitude change,
at the finish line you're 14100 feet give or take and at that sort of altitude your air
density is incredibly low.
So the problem with this is of course the engines lose power.
With a turbocharged engine you've got the ability to claw back some of that by
basically pushing the turbos harder as you go up the hill climb.
Are you going to be using some compensations for barometric air pressure in order to try
and maintain a relatively consistent power level in the car?
- So I'm going to have to plead ignorance on that a little bit, I'm the chassis guy.
We are open to be able to maintain power but I don't know all the ins and outs of
the programming of the ECU side of that.
- I did notice there you've got turbo speed sensors on each turbo, that's generally one
of the key inputs the calibration technicians are looking at but as you say, you're in
charge of the chassis so I sort of put you on the spot, something outside of your
normal area of expertise.
So let's get back to something you're probably a bit more familiar with though,
the aero, it's hard to look at this car without going past the fact that the
aero package on it is pretty amazing.
So can you give us any numbers on what sort of downforce you're expecting
developed from the car?
- So the wing is rated for about 1700 or 1800 pounds of downforce and so
we have to balance that with downforce in the front of the car.
The wing is a little bit behind the axles so we'll have to balance it with something more,
whatever the numbers work out to.
It's going to be about 2000 pounds in the front.
- What sort of speed are you talking about getting that kind of downforce at?
- I think the wing is rated for that downforce at 150 mph.
- That's not insignificant, specifically given the weight of the car, you're definitely,
particularly with a rear wheel drive car when you're trying to make that sort of
power as well, obviously getting that downforce is key to getting traction.
Look it's been really interesting getting some insight into the car.
Obviously it's a fresh build so look forward to seeing how you go next year
at Pike's Peak, I wish you all the best of luck.
- Yep thank you.
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