73 replies to this topic

[wingsbgone]

Kind of random thought/question, but what are everyone's thoughts about what vehicle (real or feasible) would be fastest at a given track (non-oval). I. e., would a older 3.5l-engined F1 with 2006 tires be fastest @ Magny-Cours (or at least a track where a large amount of testing occurs)? Or a Group-C Puegeot (aero advantage), with updated power plant? Kind of a question of aero vs. horsepower vs. tires vs. electronic controls (TC, susp, etc.).
Speculations please....

[imaginesix]

You need to stipulate some restrictions as to what vehicles may be compared? Existing designs only? Combinations of existing parts? Blank sheet designs? Components that only exist in our wet dreams?

[cheapracer]

ok I'll play your game; Williams FW11B, unlimited boost on modern tyres - totally feasable.

[murpia]

Hmm, Jaguar XJR-14 with a 2005 spec F1 V10 and ECU and modern tyres...

Regards, Ian

[Limits]

Is Magny-Cours the track? Or Monaco?

[Ross Stonefeld]

Probably some decades old F1 rules before there were limits on aero and you could run 16 cylinder engines and what not. Run with current technology understanding, of course.

[wingsbgone]

Originally posted by imaginesix
You need to stipulate some restrictions as to what vehicles may be compared? Existing designs only? Combinations of existing parts? Blank sheet designs? Components that only exist in our wet dreams?

Okay,let's go with either existing designs and/or (feasible) combinations of existing parts. The idea being that if any of us were unbelievably rich, and had the connections to acquire said parts, described vehicle could be built and actually run at the track (track is open too, but Monaco would be out as it's temporary).

[cheapracer]

Why would you bother with a naturally aspirated motor in a free for all class?

[murpia]

Originally posted by cheapracer
Why would you bother with a naturally aspirated motor in a free for all class?

Packaging. If we are talking about already realised existing designs, the last F1 V10s have the highest power / (weight * volume) coefficient ever (including the engine ancillaries and coolers). More room for aero!

Regards, Ian

[cheapracer]

Originally posted by murpia

Packaging. If we are talking about already realised existing designs, the last F1 V10s have the highest power / (weight * volume) coefficient ever (including the engine ancillaries and coolers). More room for aero!

Regards, Ian

Oh? Including 5000+hp Drag motors? or are you strictly F1 speak?

I'll stick with the Honda or BMW 1.5 turbo - 1500hp for a short time (and a good time!).

How much horsepower are you willing to sacrafice for packaging?

The Williams FW11B with no boost limit, modern diffuser and modern tyres, I'm convinced.

[MikeTekRacing]

i doubt somebody would be able to drive that thing close to its limits
anyway, the same combination would be my guess too

[desmo]

I have a feeling that with full support from an experienced tire maker, surpassing current F1 performance would probably be a relatively trivial feat, but without factory tire support it'd be near an excercise in futility.

[Limits]

If aero is free I would just put fins and rudders on the car. If it could lean on a wing through a corner you could reduce downforce/drag and tyre dependance a lot. Downforce is not really a very smart way of increasing corner speed since it increases energy consumtion, tyre wear, track wear etc. Maybe aero aided direction change/steering could really be something for the future? I can imagine it can do wonders on icy roads also on a family car?

[Powersteer]

Originally posted by cheapracer
I'll stick with the Honda or BMW 1.5 turbo - 1500hp for a short time (and a good time!).

I thought their maximum was 1,200 on funny fuel. So who is going to wire that up for some anti-lag action?

[phantom II]

No problem. Get Senna's nephew to drive it.

Originally posted by Powersteer
I thought their maximum was 1,200 on funny fuel. So who is going to wire that up for some anti-lag action?

[Ross Stonefeld]

I'd have gone with Rod Millen.

[J. Edlund]

Originally posted by cheapracer


Oh? Including 5000+hp Drag motors? or are you strictly F1 speak?

I'll stick with the Honda or BMW 1.5 turbo - 1500hp for a short time (and a good time!).

How much horsepower are you willing to sacrafice for packaging?

The Williams FW11B with no boost limit, modern diffuser and modern tyres, I'm convinced.

Those old turbo engines are quite heavy, I belive the Honda is around 140 kg and the BMW around 170 kg (excluding intercoolers). 1500 hp is probably a bit on the high side, but 1300 hp is probably possible from such an engine. But you will have a difficult time to find someone that can sell you the fuel they used.

If an existing engine design is to be used in a car whose goal is to be as fast as possible around a track, I would go for a turbocharged indycar/champcar engine or turbocharge a newer naturally aspiranted racing engine.

[cheapracer]

Originally posted by Ross Stonefeld
I'd have gone with Rod Millen.

I guess you refer to Rods Pikes Peak cars?

Which brings us to Walter in that Pikes Audi, now thats getting close to what one might conjour up if we had a road car based "run what you can"!

[cheapracer]

Originally posted by J. Edlund


But you will have a difficult time to find someone that can sell you the fuel they used.

Huh? Those fuels met rules. Numerous over the counter blends available to suit our purpose.

Quoted from BMW Motorsport's own website is that the 1.5 Turbo produced up to 1,400 hp.

Nelson Piquet was quoted (upon arrival at Williams) when first testing with Renault "BMW used up to 55 psi boost and occasionally we saw more than 1500 hp for qualifying"

[J. Edlund]

Originally posted by cheapracer


Huh? Those fuels met rules. Numerous over the counter blends available to suit our purpose.

Quoted from BMW Motorsport's own website is that the 1.5 Turbo produced up to 1,400 hp.

Nelson Piquet was quoted (upon arrival at Williams) when first testing with Renault "BMW used up to 55 psi boost and occasionally we saw more than 1500 hp for qualifying"

BMW used a synthetic fuel from BASF Wintershall specifically developed for this engine and also meet the F1 regulations. Not exactly an over the counter blend. There is an old thread about this fuel: http://forums.autosp...?threadid=34397

Much speculation about the engine power of these F1 engines. Paul Rosche, who was in charge of the development of this engine said he didn't know the exact power output as the dynos they had only went to 1280 hp or something like that. Maximum qualification power is generally regarded to be around 1300 hp.

Race power of the engine over the years:
1980: 550 hp @ 2.3 bar abs.
early 1983: 640 hp @ 2.9 bar abs.
late 1983: 750 hp @ 3.4 bar abs. (from now on using BASF Wintershall fuel)
1984: 880 hp @ 3.8 bar abs.
1985: 850 @ 3.6 bar abs.
1986: 850 hp @ 3.6 bar abs.
1987: 900 hp @ 3.8 bar abs.

and qualification power:
1983: 800 hp @ 3.2 bar abs.
1984: 1050 hp @ 4.5 bar abs.
1985: 1200 hp @ 5.4 bar abs.
1986: approx. 1300 hp @ 5.5 bar abs.
1987: not much more than 900 hp due to 4 bar abs. boost limit

Maximum speed increased over the years from approx. 9,500 rpm to 11,500 rpm.

[cheapracer]

Originally posted by J. Edlund


BMW used a synthetic fuel from BASF Wintershall specifically developed for this engine and also meet the F1 regulations. Not exactly an over the counter blend.

There seems to be some confusion here, what fuel was/wasnt available at the time doesnt apply, the rules for this thread are quite clear - there isnt any except whats reasonable and feasable today. Any number of blends commercially available today will satisfy the turbo's requirements and are as simple as methanol (as used in Indy Cars) which is available at any speedway shop in Australia for around $1+ per litre - I'm sure substantially cheaper than the BASF blend.

A note of interest is that in those days they apparently added diesel as required to slow the burn rate.

Excuse my 55 psi comment, your correction of 5.5 bar is correct - so shoot me, I'm getting old!

[J. Edlund]

Originally posted by cheapracer


There seems to be some confusion here, what fuel was/wasnt available at the time doesnt apply, the rules for this thread are quite clear - there isnt any except whats reasonable and feasable today. Any number of blends commercially available today will satisfy the turbo's requirements and are as simple as methanol (as used in Indy Cars) which is available at any speedway shop in Australia for around $1+ per litre - I'm sure substantially cheaper than the BASF blend.

A note of interest is that in those days they apparently added diesel as required to slow the burn rate.

Excuse my 55 psi comment, your correction of 5.5 bar is correct - so shoot me, I'm getting old!

No, they never added diesel to the fuel.

In any case, methanol is a very different fuel compared to what they used. Some major changes to the engines would be required. The kind of fuels used in F1 back in the days were specifically designed to work well in a high speed, high boost engine where combustion often becomes unstable. If you use a different fuel, don't expect to get the same power with an over the counter fuel.

[cheapracer]

Originally posted by J. Edlund


No, they never added diesel to the fuel.

In any case, methanol is a very different fuel compared to what they used. Some major changes to the engines would be required. The kind of fuels used in F1 back in the days were specifically designed to work well in a high speed, high boost engine where combustion often becomes unstable. If you use a different fuel, don't expect to get the same power with an over the counter fuel.

Are you joking? Dont expect to get more horsepower from methanol/nitro/benzine/acetone etc. blends over a regulation octane rated (102) blend of toluene (paint stripper) and heptane?

I'd put money on tipping methanol straight into the tank and getting a power increase, no mods. (air fuel mixture corrected, duh).

By the way, I used to buy toluene over the counter at many BP depots, I used to mix 50/50 with BP AV 130 bought from any small airport (Archerfield, Brisbane in my case) but admit I've never had experience with heptane which is commercially available.

My recent years of racing have all involved using methanol, what a dream, cool engines, no knock sensors activating, excellent throttle response (hi comp), broader power spread (hi comp) and may I mention MORE HORSEPOWER!! and I never flushed the tank or fuel systems after races and I never had starting problems, 2 myths of methanol.

Your wonder fuel toluene can be bought at many paint suppliers, how much more over the counter than that can you get?

[J. Edlund]

Originally posted by cheapracer


Are you joking? Dont expect to get more horsepower from methanol/nitro/benzine/acetone etc. blends over a regulation octane rated (102) blend of toluene (paint stripper) and heptane?

I'd put money on tipping methanol straight into the tank and getting a power increase, no mods. (air fuel mixture corrected, duh).

By the way, I used to buy toluene over the counter at many BP depots, I used to mix 50/50 with BP AV 130 bought from any small airport (Archerfield, Brisbane in my case) but admit I've never had experience with heptane which is commercially available.

My recent years of racing have all involved using methanol, what a dream, cool engines, no knock sensors activating, excellent throttle response (hi comp), broader power spread (hi comp) and may I mention MORE HORSEPOWER!! and I never flushed the tank or fuel systems after races and I never had starting problems, 2 myths of methanol.

Your wonder fuel toluene can be bought at many paint suppliers, how much more over the counter than that can you get?

If you think that qualification fuel was a simple blend of toluene and n-heptane YOU must be joking. I hardly think that F1 teams spended $300/liter on paint thinner.

The fuel developed for F1 turbo engines was designed to meet a certain specification regarding research octane racing, boiling curve, no oxygenates and so on that was similar to ordinary pump petrol. Beyond that you could essentially make any kind of blend you want, and that was what they did. They reseached for chemical components that had postive effects particulary in high boost, high speed engines. If the blend didn't meet the specifications some other components was added, low octane chemicals to reduce the octane rating or low density chemicals to reduce the density. The components used for the blends where syntheticly produced and not typically found in ordinary gasoline, many of them where also very toxic.

Methanol has specific demands on the fuel system in order to avoid problems, that itsn't any myth. There are several technical papers availible on the subject.

[murpia]

Originally posted by cheapracer

How much horsepower are you willing to sacrafice for packaging?

Depends on the track, but I want a 1000bhp engine that's less than 100kg, less than 150mm centre of gravity height, less than 300mm wide at the sump and with a total heat rejection requirement (that includes the intercoolers, turbo fanatics) of less than 1MW.

The nearest you'll get is the last of the V10s, with relocated ancillaries and updated combustion performance from the V8s.

Give me a track and I'll tell you the BHP/kg, BHP/CoG, BHP/cooler area trade-offs...

Regards, Ian

[Greg Locock]

I'd like to see that. 42 or 43% efficient.

Hmm..

[blkirk]

And I'd stick that engine in one of these:

http://www.vicelford...ery/23large.jpg

[GeorgeTheCar]

And the only questions is "Why?"

That would have been the answer in 1970 but 37 years later we have solutions that Jim Hall tried to provide through brute force with a second engine.

The Chaparral was complicated, heavy and unreliable.

I was as big a Jim Hall fan as existed but that solution never entered my mind.

Jim Hall was ain imaginative, creative, dedicated engineer. I cannot imagine him proposing that car for the task.

[blkirk]

Originally posted by GeorgeTheCar
And the only questions is "Why?"

The 2J was, and still is, a good solution.

With the 2J, downforce is not a function of speed. The car can generate over 10,000 lbs (44,500 N) of downforce sitting still. We should easily be able to build the car to LMP1 weight (925 kg, 1982 lb) using modern composite materials. As a result, if the tires are up to it, we should be able to pull more than 5 Gs around ANY turn. The car could also accelerate at 5 Gs straight off the starting grid and decelerate at 5 Gs all the way from top speed to a dead stop. No car that relies on velocity to generate downforce can do any of this.

Drag and downforce are no longer linked. Wings have an inherent trade-off between downforce and drag. If you increase the angle of attack to get more downforce, drag goes up, too. With the 2J, drag is essentially constant. There may be a slight correlation between drag and fan speed, but it should be nothing like the difference in drag on an F1 car between Monza and Monaco.

The 2J was only unreliable because of their choice of auxilary engine. We can avoid that mistake.

We just need to find a driver than can survive a sustained 5 Gs.

[desmo]

A modern 2J concept fan car could surely be built today- assuming factory tire support- that would lap seconds faster than any F1 for a fraction of an annual F1 budget?

[murpia]

Originally posted by Greg Locock
I'd like to see that. 42 or 43% efficient.

It's been a while since I saw any hard numbers but about 750kW would also head off down the exhaust so it's more like 30% efficient.

Regards, Ian

[Greg Locock]

Oops

You are right, sorry.

[McGuire]

Originally posted by Ross Stonefeld
I'd have gone with Rod Millen.

One of my more memorable experiences: watching Rod Millen drive that Toyota thing up Pikes Peak. Holy crap.

It was essentially an unlimited IMSA GTP chassis with a funny car pickup body. The ground effects tunnels were about two feet deep. A full-grown man could crawl all the way in and hide on either side. I asked him where the boost control was set and he shrugged. What boost control. By the time you get to 8,000 ft you don't need no stinking boost control.

Come to think of it, something like that would make a solid entry in our little imaginary Formula Libre here.

[McGuire]

Originally posted by blkirk


The car could also accelerate at 5 Gs straight off the starting grid

Given enough horsepower, and it would have be a lot.

[Bob Riebe]

Well let's see. today one can get a big block US engine that can reach 600 inches cubed and still be over-square while weighing no more or less than the linerless Can-block, and these engines can be put into the old ground effects Indy cars without too much work.

Todays engine builders can get 2.2 hp per inch out of US engines without radical tuning so lets see: that would be at least 1,300 hp, in a car that weighed between 1,500-1,600 lbs., on tires as wide as one can find.
Huge torque and hp throught he entire rpm range,(and mountain motor races engines, 815 in. cu. redline in the 8,000 range) I would say such a vehicle could run with anything.

[murpia]

Originally posted by blkirk
The car could also accelerate at 5 Gs straight off the starting grid

Originally posted by McGuire
Given enough horsepower, and it would have be a lot.

Let's see... 925kg at 5g, let's round that to 45kN initial acceleration force (F=ma).

Assume a tyre radius of 30cm, equals a torque of 15kNm. For our hypothetical 1000bhp (~750kW) at say 18,000rpm (~1900rad/s) that means a torque of (750,000 / 1900) = 395Nm so a gearbox reduction of 395/15,000 = 38:1

So you could reach ((1900 / 38) * 0.3 ) = 15m/s in that particular 1st gear (54kph).

Someone better check my maths though, been a long day...

Regards, Ian

[swintex]

Originally posted by McGuire


The ground effects tunnels were about two feet deep. A full-grown man could crawl all the way in and hide on either side.

It doesn't show the venturis, but it does show there's plenty of room…

[Wolf]

Ian, do Your calculations mean we don't want two Audi CVTs (up to 250Nm, IIRC) mounted 'DAF style' (each being driven off the diff)? I think it might improve the acceleration a bit.

[murpia]

Originally posted by Wolf
Ian, do Your calculations mean we don't want two Audi CVTs (up to 250Nm, IIRC) mounted 'DAF style' (each being driven off the diff)? I think it might improve the acceleration a bit.

You couldn't mount them 'DAF style' that far down the driveline, the torque would be too high (7.5kNm in each driveshaft for RWD).
What's the ratio range of the Audi CVT? And approx size and weight?
I like the idea of 4 CVTs in parallel driving all 4 wheels independently - you might not even need a steering mechanism!
You'd need to control them more like torque actuators, specify the torque via an ECU based on what you wanted the vehicle to do. My understanding is that a Torotrak can be controlled that way using hydraulic pressure control - don't know about the Audi CVT.
Regards, Ian

[Powersteer]

Jean Alesi, Monaco on a regeared Lancia S4 but anti-lag instead of a supercharger with the traction system from Loebs Citroen. Engine done to give 1000hp, beat that Senna.

[Wolf]

Ian, haven't thought about it. Then we need to split torque at engine revs and each CVT should have a final drive of it's own*.

* but I thought that's the way DAF used them, because their belts (leather?) couldn't take a lot of torque

Here's some info on Audi CVT (at least ratios)- http://www.audi.ie/a...saloon/0/0.html . It takes even 300Nm...

[McGuire]

Originally posted by murpia


38:1

Be serious.

[murpia]

Originally posted by McGuire
Be serious.

I am entirely serious about a 38:1 reduction ratio from an 18,000rpm engine to 0.3m radius tyres allowing a 925kg vehicle to accelerate at 5g with 750kW engine power. Please check my maths and point out any errors (aside from a neglect of transmission efficiency).

I agree it sounds impractical to accelerate in such a low gear, but the original calculation was in response to a post querying how much power would be required to accelerate at 5g, which I answered. Carrying on the analysis a bit it appears that you would actually be in that gear for <0.4s and of course the clutch system represents a challenge... More likely, especially given the later posts, something could be done with a CVT that would therefore pass through a ratio of 38:1 at that point. This is the total reduction ratio, including crankshaft step-down, gear ratio cluster or CVT, cross-shaft reduction and final-drive reduction.

I have a simulation that handles this stuff easily, it's quite well validated and fun to use for this kind of thing. Have a look in this months (July 2007, Issue 81) of RaceTech magazine if you are able.

Regards, Ian

[Greg Locock]

You are ignoring rotational inertia in the engine and driveline

[djellison]

No one's considered the banned FW15C CVT.

I'd take an '06 F1 engine. The 1000+bhp of older engines might be a nice stat - but the driveability of the newer engines would counter that I would have thought. Active suspension, TC, ABS, CVT, could be a hell of a mix.


Doug

[murpia]

Originally posted by Greg Locock
You are ignoring rotational inertia in the engine and driveline

Agreed. Instead we have an arbitrarily assumed vehicle weight of 925kg for no other reason than it's the LMP1 class limit. At this level of 'fun' analysis I am happy to lump drivetrain inertia into the vehicle weight. For sure there are bigger issues than this if one is serious about building the thing - the clutch would be my main concern.

Regards, Ian

[McGuire]

Originally posted by murpia

I am entirely serious about a 38:1 reduction ratio from an 18,000rpm engine to 0.3m radius tyres allowing a 925kg vehicle to accelerate at 5g with 750kW engine power. Please check my maths and point out any errors (aside from a neglect of transmission efficiency).

I agree it sounds impractical to accelerate in such a low gear, but the original calculation was in response to a post querying how much power would be required to accelerate at 5g, which I answered. Carrying on the analysis a bit it appears that you would actually be in that gear for <0.4s and of course the clutch system represents a challenge... More likely, especially given the later posts, something could be done with a CVT that would therefore pass through a ratio of 38:1 at that point. This is the total reduction ratio, including crankshaft step-down, gear ratio cluster or CVT, cross-shaft reduction and final-drive reduction.

I have a simulation that handles this stuff easily, it's quite well validated and fun to use for this kind of thing. Have a look in this months (July 2007, Issue 81) of RaceTech magazine if you are able.

Regards, Ian

Ohhhhhhhhhh, a sim. That clears up everything for me.

I was sort of wondering how this conclusion had been derived, apparently bereft of any human thought or reasoning. And as it turns out that is exactly how it was accomplished. Carry on!

[murpia]

Originally posted by McGuire
Ohhhhhhhhhh, a sim. That clears up everything for me.

I was sort of wondering how this conclusion had been derived, apparently bereft of any human thought or reasoning. And as it turns out that is exactly how it was accomplished. Carry on!

Sorry, I'm not sure I understand you...

Do you mean the idea of this 'quickest vehicle' is thoughtless and unreasonable? If so I agree and anyway this is all just a bit of fun, isn't it?

Regards, Ian

[dosco]

Originally posted by blkirk
With the 2J, downforce is not a function of speed. The car can generate over 10,000 lbs (44,500 N) of downforce sitting still.

What is the L/D ratio of that, and how much energy are you using to generate downforce (considering you have a separate engine and all)?

Not saying a fan car is bad or anything, they were innovative for their time.

May I suggest you take a look at the Toyota Eacgle Mk.III pages in Mulsanne's corner - 10,000 lb downforce with a nice L/D ratio of 4.5 (or so).

Drag and downforce are no longer linked.

BS. There is no free lunch.

Wings have an inherent trade-off between downforce and drag. If you increase the angle of attack to get more downforce, drag goes up, too.

What about the underbody? Using the underbody, you can get much better L/D ratios than with wings. Add variable geometry underbody skirts and you have a real winner.

Let's not forget about the drag of the other bits of the car.

[McGuire]

Originally posted by murpia

Sorry, I'm not sure I understand you...

Do you mean the idea of this 'quickest vehicle' is thoughtless and unreasonable? If so I agree and anyway this is all just a bit of fun, isn't it?

Regards, Ian

No, the idea of an unlimited car is fascinating. The 38:1 first gear is ridiculous. How about a little common sense. We ought to be able to come up with something that could actually run around a track if built.