Will a bike engined hillclimb car ever win the British Hillclimb Championship?

[zac510]

Dennis, I follow the bikes a little on the side but from what I understand, they tune the engines for a nice wide flexible powerband due to the instability of the motorbike (high COG, two wheels, etc).

[hillsprint77]

Taking simply power to weight ratios as a guide it looks like a bike engine would have to be producing in excess of 350 hp to be getting close to a V8, which in rough terms ready to run with the driver on-board has an easy 1bhp per kg.

My Jedi of a few years ago weighed in at 285 kg, I was 70kg and it made 215 bhp and 115lb/ft from its 1370 GSXR. All that gives just over 0.6 bhp/kg, A Busa is apparently 10kgs heavier again. Powertec, who's figures I've found reliable in the past, say their best 1600 Busa is 270bhp. Fitting one of those you still only get 0.775 bhp/kg.

If you go any bigger on the bore you start to get shrouding and offset problems with the head, and stroking the engine will reduce it's rev potential.
Turbo charging brings in lag problems and also adds significant weight, but will eventually produce the power.

However, there is something in the back of my mind about how much force must be applied vertically on a square inch of rubber to transmit a certain amount of horsepower. So if you could get a really light high powered bike engined car how would it put the power down and how much aero drag would be generated in keeping it on the ground

I suppose an even easier way to see how far the BECs need to go is look at the speed trap times at the likes of Shelsley, I'm sure someone can quote them.

The old line of "you can't beat cubes" still holds good.

But mind you a Wee Wicked One is still much better than a Big Dopey One

[Jimbo88]

Now that Ilmor MotoGP has gone belly up, maybe someone with a wheel barrow of cash could slot of of those in a BEC. I hear they have a bunch kicking about.
They have all the bells and whistles, super light tiny things trick as you like with the f1 spec pneumatic valves and everything. Heard that they can rev to 22k, but then high revs are bloody useless cos you dont get many hillclimbs on hanger straight

[Dennis.Doyle]

Interesting facts & figures there Michael. Worth comparing with some of those from GWJ re. the V10 & V6 Goulds on this forum:

http://tentenths.com/forum/showthrea...t=94157&page=2

Must admit I'm always gobsmacked by how light & powerful both the BECs & big single seaters are - I have difficulty controlling 180bhp, propelling 475kg!

Re. the limiting factors of light weight & traction. I really can't make up my mind, but FWIW:

Top cars accelerate at much more than 1G, i.e. <2 secs for 1st 64ft, hence they are able to transmit more than 1kgf of tractive effort for each kg they are accelerating. Obviously the laws of glue apply here rather than Newtonian friction. I'd think that every kg you can shed you can make use of for acceleration & cornering - assuming A45's are soft enoough of course.

I'd wondered if the transmission isn't really the limiting factor? That is where the BECs really save weight. It's also a reliability problem for some competitiors I've spoken to running fairly cooking bike engines (<180 bhp).

Either way, another US saying that applies is "a good big un will always beat a good little un" - don't suppose the front runners have gone from 2.6 to 2.8 NME V6s 'cos they are slower!

Re. Jimbo88's comment on the Ilmors - I'd also wondered if there was any possibility of trickle down from MotoGP to speed events. Take your point about hangar straight & do remember Glyn Sketchley in a 500 Jedi finishing ahead of all the V8's at 3 Sisters (a sprint, but a twiddly one!) in 2000.

Still reckon it's a case of horses for courses.

[Steve Wilkinson]

Originally Posted by Jimbo88

Now that Ilmor MotoGP has gone belly up, maybe someone with a wheel barrow of cash could slot of of those in a BEC. I hear they have a bunch kicking about.
They have all the bells and whistles, super light tiny things trick as you like with the f1 spec pneumatic valves and everything. Heard that they can rev to 22k, but then high revs are bloody useless cos you dont get many hillclimbs on hanger straight

However they would be pretty good in the British Sprint Championship!

[hillsprint77]

Ofcourse when you are doing high sppeds, such as some of the BSC venues, you then encounter the aero drag factor and frontal area is a main factor. Hence you need something with the frontal dimensions of a Basil Davenport's Spider, including 3 inch wide tyres. Might be fine if you had a rolling start and the Championship consisted of Brighton, Brighton and err Brighton

Once again cubes win, you still need brute force to push it through the air !!

So I'd save your pennies and not bother lining Mario's pockets

But if you want 1100 class wins then go ahead

[DJ Racecars]

Originally Posted by Steve Wilkinson

Currently the attempts to either Turbocharge or Supercharge bike engines has not been successful, which isn't to say that they will continue to be so. However I suspect that they will still struggle to beat a good V8.

What makes you say that?

The lastest superchargered version of our Firehawk (owned by Wallace Menzies) is putting out 360 bhp @ the wheels (172lb/ft torque) from a 1400cc Busa and we know more power is available either by running an intercooler or methanol. (this equates to 1080 bhp/ton which is compareable to a V8 powered unlimted class car).

Last weekend at Knockhill the car finished 3rd which isn't bad when you consider Roy was pulling 175mph down the straights compared to our 138 mph (on the rev limiter in 6th)

[DaveK]

DJ
If you take a Gould @ approx 450kgs/650bhp you get 1444 bhp/ton. which as Hillspeed says "you need brute force" to push it through the air.

The extra benefit of having excess power is that you can then run more aero without having to worry about the drag.

Dave

[Steve Wilkinson]

Originally Posted by DJ Racecars

What makes you say that?

The lastest superchargered version of our Firehawk (owned by Wallace Menzies) is putting out 360 bhp @ the wheels (172lb/ft torque) from a 1400cc Busa and we know more power is available either by running an intercooler or methanol. (this equates to 1080 bhp/ton which is compareable to a V8 powered unlimted class car).

Last weekend at Knockhill the car finished 3rd which isn't bad when you consider Roy was pulling 175mph down the straights compared to our 138 mph (on the rev limiter in 6th)

I posted the comment about forced induction motor bike engines prior to my trip to Knockhill.

After seeing Wallace Menzies and the Firehawk I have to say that this combination looks very impressive. Still a few wrinkles to iron out but at Knockhill it went exceptionally well.

So my latest conclusion is that a forced induction bike-engined single seater could do very well indeed if committed to a full season in the British Sprint Championship. I remain to be convinced on their suitability for the British Hillclimb Championship - hopefully I will be won over at Doune!

[wight jr]

What is impressive is that to have all that power and get away with little rear wheels. You would also think that it would have a lot of strain on the gearbox being designed for a lot less load.

[Paul Ranson]

It's possible that the gearbox survives because of the little wheels?

I think there is probably a reasonable correlation between power and speed trap readings. Tony Hunt's Force is fitted with a supercharged Haybusa and provides a sort of benchmark.

Looking at last August's Gurston Down (first speed trap) and Shelsley meetings (finish speed),

Tony Hunt      115 115
Tom New        111 122
Trevor Willis  112 122
Groves/Ranson  134 144

Trevor has a lot more go this year, but is having transmission difficulties. Tom's Shelsley best was a bit of a one off, he was more usually at 115ish. Tony's relatively poor Shelsley is probably related to handling difficulties in Top Ess (check out his Dunn video on StreetFire).

There's a huge gulf between 115mph and 134mph, I don't see what you can do to the bike engine to bridge it., especially given the relative friendliness of the NME and the overall effectiveness of the GR55 chassis.

Hopefully we'll get some more good data over the next two meetings, and I'm looking forward to seeing Graeme out again, especially at the Gurston and Shelsley dynamometers...

Paul

[xbgs351]

Originally Posted by DaveK

DJ
If you take a Gould @ approx 450kgs/650bhp you get 1444 bhp/ton. which as Hillspeed says "you need brute force" to push it through the air.

The extra benefit of having excess power is that you can then run more aero without having to worry about the drag.

Dave

When talking about pushing through the air, the weight of the car isn't a factor, but the power, frontal area and Cd is.

[Steve Wilkinson]

Originally Posted by xbgs351

When talking about pushing through the air, the weight of the car isn't a factor, but the power, frontal area and Cd is.

I would agree however most of the British Hillclimb cars have a barn door hanging out of the back; you would call it a rear wing!

The brute force is needed to push this through the air.



Martin Groves at Craigantlet.

[hillsprint77]

Ofcousre Steve it's just not the V8s that have "barn doors" so even with a mere 270hp you still need some downforce

[bentimingstrut]

Look about the same I would say. Although I suspect the barn door fitted to the Force may be a little lighter.

[Jeff 8]

Is that 270 bhp from a bike engine?

Jeff

[blackx]

Originally Posted by Jeff 8

Is that 270 bhp from a bike engine?

Jeff

Yes....

[Hitech]

I think that 270 bhp from a normally aspirated Hayabusa on carbs and pump petrol is very optimistic, even though Cookies engine was exceptional.

[Steve Wilkinson]

Originally Posted by hillsprint77

Ofcousre Steve it's just not the V8s that have "barn doors" so even with a mere 270hp you still need some downforce

Precisely my point! The 3.5 litre NME engined Gould has more power and torque available to push its "barn door" through the air so will inevitanbly be quicker given two drivers of equal ability.

As for the weight factor, I doubt that the difference in weight between the two rear wings would cause any great performance differential. Possibly the reverse as a heavier rear wing might (a) not deform as much under the immense pressures, and (b) with its extra weight give better traction at slow speeds.

[blackx]

Originally Posted by Hitech

I think that 270 bhp from a normally aspirated Hayabusa on carbs and pump petrol is very optimistic, even though Cookies engine was exceptional.

http://www.powertecracing.com/index.php


Makes for interesting reading

[Hitech]

'Makes for interesting reading'

Of course when you are selling engines it does pay to look on the optimistic side!

[blackx]

Originally Posted by Hitech

'Makes for interesting reading'

Of course when you are selling engines it does pay to look on the optimistic side!

So they are lying then

[Dennis.Doyle]

Originally Posted by blackx

So they are lying then

Do have to ask how much "Ram air effect" they are assuming in those graphs. Would they be assuming you are doing 140mph for example?

However you look at it though, they are pretty impressive - relatively flat curves too.

[blackx]

They quote a figure of 4% whatever that means

[DaveK]

Very interesting power figures

There 1585cc engine gives 35 bhp and 48 lb/ft torque more than my engine measured on the dyno , yet the speed trap figures for cars with these engine fitted are the same as mine at harewood .

I'll have to start telling everybody my engine has 270 bhp now

Dave