Frame/Engine/Brake questions

In Driving Ambition, they state that the redline of 7500 RPM in the road car was acheived without resorting to exotic materials like titanium (for the valves and stuff). The LM's redline is 8500 - did they use titanium and composites for the LM's modified engine?

What material is the frame of the road car? I couldn't find that in the book anywhere.

Finally, what is the weight of the iron brakes? DA states that the weight target was "quietly rewritten to 1018 kg", but that was over carbon brakes of the day. I assume that the silicon carbide brakes of the CGT could be 20+ KG lighter?

Thanks guys

Your first question is a good one that I don't know the answer to. Unfortunately I've never really seen a detailed spec on the true differences that seperate the S70/2 from the from the S70/2 GTR LM found in the F1 LM. Also, there were three engines classified as S70/3 GTR that went into the three GTR production years. The first two were only slightly different from each other, but the ones for the '97 longtails actually featured a shorter stroke and several other changes. It would be great to have someone who was involved in the engine program for those years give us a proper breakdown on that.

The McLaren doesn't really have a frame - the entire chassis is made completely of carbon fiber. As Tiff said in the famous TopGear clip:

...lightweight and strong, yet it starts life as nothing more than an expensive roll of cloth. Each car is a jigsaw of 5000 pieces of resin impregnated carbon fiber pressed around 70 different molds in anything from 2 to 17 layers. Each mold is bagged up and held in a vacuum before being cooked for three hours in this huge oven under 90psi of pressure at 125 degrees centigrade to bond it together. The cured carbon fiber pieces are then stuck together rather like building a giant Airfix model with full sized parts until you have a complete bodyshell ready for the paintshop.

I've never heard a better description, so it was worth cycling through the clip a few times to get it all down.

No clue on the exact weight penalties of the Brembos -vs- a modern day carbon-ceramic brake system like the Carrera GT and Enzo have. I'm sure that the figure is out there if someone wanted to look for it, but maybe not an exact figure for the F1. I know that Gordon desperately wanted carbon brakes for the car, but at the time their function at low temperatures was not satisfactory for road use. I'm betting that if he could change one thing about the car using today's advancements that would certainly be it.

>8^)
ER

Very good question. I would be interested in the weight of PCCB/other carbon composite brake assemblies too. I will try to find out.

The other thing to know, of course, is how much the McLaren cast iron rotors weigh.

Also, we have the 100-0 braking distances for a given weight (1018kg for the McLaren F1). Can someone find out the 100-0 braking distances for Porsches with PCCB and the Enzo (carbon composite brakes), as well as their weights?

No clue on the exact weight penalties of the Brembos -vs- a modern day carbon-ceramic brake system like the Carrera GT and Enzo have. I'm sure that the figure is out there if someone wanted to look for it, but maybe not an exact figure for the F1. I know that Gordon desperately wanted carbon brakes for the car, but at the time their function at low temperatures was not satisfactory for road use. I'm betting that if he could change one thing about the car using today's advancements that would certainly be it.

>8^)
ER


Thats interesting actually. Everybody who has driven an Mercedes SLR McLaren has complained that the carbon ceramic brakes have no feel at low speed. Yet the same criticism isnt levelled at the Carrera or the Enzo. So its clearly something McLaren cant get right. Which surprises me as you'd think they would be able to.

Thats interesting actually. Everybody who has driven an Mercedes SLR McLaren has complained that the carbon ceramic brakes have no feel at low speed. Yet the same criticism isnt levelled at the Carrera or the Enzo. So its clearly something McLaren cant get right. Which surprises me as you'd think they would be able to.Remember though that the differences between the F1 and SLR's braking systems are as great as they come. The SLR uses the Bosch Electro-Hydraulic Braking system, a sort of "fly-by-wire" system that was first introduced in the current generation SL. The F1 on the other hand, at GM's insistance, doesn't even have a servo.

I don't have figures but I can vouch for the fact that the SLR's disks are pretty light (less than the ally calipers) and the F1's are pretty heavy (probably twice that weight).

Incidently Peloton, I think you'll find that Tiff actually says "carbon fibre" ;)

Your first question is a good one that I don't know the answer to. Unfortunately I've never really seen a detailed spec on the true differences that seperate the S70/2 from the from the S70/2 GTR LM found in the F1 LM. Also, there were three engines classified as S70/3 GTR that went into the three GTR production years. The first two were only slightly different from each other, but the ones for the '97 longtails actually featured a shorter stroke and several other changes. It would be great to have someone who was involved in the engine program for those years give us a proper breakdown on that.

The McLaren doesn't really have a frame - the entire chassis is made completely of carbon fiber. As Tiff said in the famous TopGear clip:



I've never heard a better description, so it was worth cycling through the clip a few times to get it all down.

No clue on the exact weight penalties of the Brembos -vs- a modern day carbon-ceramic brake system like the Carrera GT and Enzo have. I'm sure that the figure is out there if someone wanted to look for it, but maybe not an exact figure for the F1. I know that Gordon desperately wanted carbon brakes for the car, but at the time their function at low temperatures was not satisfactory for road use. I'm betting that if he could change one thing about the car using today's advancements that would certainly be it.

>8^)
ER

Thanks much Pelo...Now that you've said that, the Driving Ambition chapter called "Structures" makes a lot more sense ;)

F1 Monster, the weight of the F1 is not 1018KG, 1000 KG was their target, the final kerb weight is something greater than that. I'm too lazy to walk downstairs.
However, that's a great question. Personally, I think the modern supercars will rape the mclaren, just because of the tires. Given equal tires, it'd be hard for them to edge out the F1, because of the near perfect weight distribution at braking (B&B foil) of the F1, and because today's rotors are more focused on lighter weight and no fade (I just heard that, who knows).

I think a better comp could be made by simply fitting the Carrera GT's brakes to the McLaren F1. Or the enzo's, but I got the impression the CGT's are more advanced (lighter).

Anyway, the reason I asked all this was:
1) Just trying to get an idea of how much more power BMW could make from an engine designed today at the F1's old standards. It's kinda scary when you think about it. I assume they could get a lighter and smaller engine with the same or better power curves.
2) The frame...if it had one, I guessed it would be a conventional steel frame. A lot could be gained from creating an alumnium frame (C6 Z06), or a magnesium (not done AFAIK) or a carbon fiber one. But....we now know nothing can be gained :)
3) Gaining a better sprung/unsprung ratio.

The McLaren doesn't really have a frame - the entire chassis is made completely of carbon fiber. As Tiff said in the famous TopGear clip:To be technically correct, the majority of the F1 chassis is carbon fiber, while the front and rear sub frames are made from aluminum (carbon fiber has bad heat resistance and fatigue limit properties.)

To be technically correct, the majority of the F1 chassis is carbon fiber, while the front and rear sub frames are made from aluminum (carbon fiber has bad heat resistance and fatigue limit properties.)


Thank you for that information. Do you know why magnesium was not considered?

Thank you for that information. Do you know why magnesium was not considered?My guess is that there are three reasons:

1. Magnesium's creep qualities aren't that good (it'll slowly deform due to stress and heat.)

2. It isn't as strong and stiff aluminum.

3. Making magnesium by a process other than casting is difficult.

Magnesium is often used in wheels and bicycle suspension forks where light weight is necessary, but where the parts aren't likely to encounter very high forces and stresses. In both situations the wheel and fork parts are cushioned by a pneumatic tire on one side and a sprung suspension on the other side.

Magnesium is also difficult to work with if you're not making a casted part (pouring liquid metal into a mold.) Extrusion (forcing through a hole) isn't an easy process to do with magnesium. Basically, it's easy to make wheels, transmission housings, and bicycle fork legs using magnesium, but it's hard to make tubes and other shapes that have thin walls.

Thanks.

I heard that magnesium is actually stronger than aluminum but I guess that's wrong. I know it is being used in the c6z06 as the engine cradle which can't be shaped much different than a frame, right?

Remember though that the differences between the F1 and SLR's braking systems are as great as they come. The SLR uses the Bosch Electro-Hydraulic Braking system, a sort of "fly-by-wire" system that was first introduced in the current generation SL. The F1 on the other hand, at GM's insistance, doesn't even have a servo.



I thought about this. And both Ferrari and Porsche use Brembo brakes. and Im guessing its not much different to a regular modern braking system. I believe the F1 runs Brembos too.

So maybe its down to the fly-by-wire as used on S,SL and E (and presumably CLS) Mercs. Maybe fly by wire isnt the answer Mercedes and Bosch hoped it to be.

Therefore, Brembo have managed to get it right in the intervening decade. Whilst Bosch have gone down the completely wrong avenue with regards to a performance car braking set up. They've focused entirely on stopping power instead of thinking about feel. And Brembo have got the balance between power and feel just right.

If anybody on here has an SLR get some Brembos on it. :D

Thanks.

I heard that magnesium is actually stronger than aluminum but I guess that's wrong. I know it is being used in the c6z06 as the engine cradle which can't be shaped much different than a frame, right?Mangesium is probably superior in strength/weight but for overall strength aluminum is better. In the 12 years since the F1 was first produced as a production car, I'd expect that advances in materials science yielded stronger alloys.

As for the engine cradle on the new Corvette...you'd have to find out how the parts are shaped. Magnesium is difficult to make into any thin-wall shape.

I have a couple pics of it I'll dig up.

I'm not trying to figure out if Gordon Murray should have used magnesium - he would have if he should have. I'm just trying to figure out the potential room for improvement.

Here's one
http://flinger.ath.cx/corvette/1803frame.JPG
Big pic.

I have a couple pics of it I'll dig up.That picture is nice, but doesn't show me much of the actual support structure for the engine. A chassis without the engine would be more useful.

Anyway, I was looking through some articles and pictures I have, and I'm pretty sure that the sub-frame members aren't tubulur extrusions -- they're solid, machined pieces. Given the fact that magnesium is still softer than aluminum, and will still creep more (this can be a big factor) I'm still pretty sure that's why it wasn't used.

Creep is the gradual deformation of a part over time. The thing that makes creep different from fatigue (breaking due to repeated forces over time) and yield (pull on something till it breaks) is that creep happens under high temperatures, and low loads. The crystalline structure of the metal just begins to slip, even though you're not putting all that much force onto it. Think of it as the floor in an old house sagging over time.

Remember, the maximum yielding strength of a material (how much force it takes to break it) is not the only consideration of why it is used. Unless you have an understanding of materials science, the reasons for the choices may not be obvious. Of course I need to say that I'm not a material scientist, so there may be other considerations such as manufacturing limitations with magnesium that further ruled out its use in the sub-frames.

A quick bit of research about magnesium alloys on google has given me the impression that in the 12 years since the F1 debuted, metallurgy has produced stronger, and more creep resistant magnesium alloys (due to the number of articles referencing magnesium that have improved creep resistance.)

I'm not trying to figure out if Gordon Murray should have used magnesium - he would have if he should have. I'm just trying to figure out the potential room for improvement.Engineering is best left to engineers =)

If you wanted to make the F1 lighter, give it lighter brake rotors. The brake rotors seem to be the place that the F1 could most easily lose some weight.

A quick bit of research about magnesium alloys on google has given me the impression that in the 12 years since the F1 debuted, metallurgy has produced stronger, and more creep resistant magnesium alloys (due to the number of articles referencing magnesium that have improved creep resistance.)

Quote:I'm not trying to figure out if Gordon Murray should have used magnesium - he would have if he should have. I'm just trying to figure out the potential room for improvement.

Engineering is best left to engineers =)

If you wanted to make the F1 lighter, give it lighter brake rotors. The brake rotors seem to be the place that the F1 could most easily lose some weight.

I'm aware. I'm not engineering, I'm looking at what we've done over 12 years with materials and seeing what Gordon could do if he were creating the car today. I thought of the brake rotors, that is being discussed in this thread.

Thanks for the help.

Ok. I didn't have any qualms about what you're saying, but I was a bit confused at what you were trying to get at.

FYI:

Carbon fiber rotors from the McLaren GTR weigh 4.90 lbs (2.22 kg) sans the rotor hat. (Just weighed one this morning.) Add about another kg for the hat.

FYI:

Carbon fiber rotors from the McLaren GTR weigh 4.90 lbs (2.22 kg) sans the rotor hat. (Just weighed one this morning.) Add about another kg for the hat.


:bigthumb: