Pescarolo tub revealed

[HORNDAWG]

Originally Posted by chernaudi

The only problem when you want to downsize an engine's capacity is that you can't really debore it as far as I know. That has to be done when the block is first bored. The only way that you can debore a block is if you recast it. If anyone knows anyother method, please let me know.

Basically, the stroke determines compresstion ratio and for sure torque. The old Bentley 4.5s had prodigous torque, even before the superchargers were bolted on. And the incresed capacities seen in the Judd V10s(from 4, to 5, and now 5.5 liters) is probably mostly stroke increases.

Paul is right. Sleeves/ liners to decrease the bore. Stroke has something to do with compression but is not THE determining factor. That is dictated by piston config. and combustion chamber size together yielding the final combustion area in relation to max cylinder capacity.Thats compression ratio! Torque is influinced by rod length witch dictates how long the piston stays static in the bore. Another factor in torque is bore vs stroke, over bore( bore larger than stroke) produces more torque but can not rev as high.Under bore revs higher but does not produce as much torque. Not a complete explanation but that takes to much typing for me!!! Theoretically a square bore, bore and stroke the same, is best.

L.P.

ps. Also groups of three theoretically are best (3,6,9,12)

[Hammerdown]

"Another factor in torque is bore vs stroke, over bore( bore larger than stroke) produces more torque but can not rev as high.Under bore revs higher but does not produce as much torque."

Not being funny, but is that right? I always thought that short stroke engines were the revers and long stroke the torquey ones.

[HORNDAWG]

Originally Posted by Hammerdown

"Another factor in torque is bore vs stroke, over bore( bore larger than stroke) produces more torque but can not rev as high.Under bore revs higher but does not produce as much torque."

Not being funny, but is that right? I always thought that short stroke engines were the revers and long stroke the torquey ones.

With the stroke being equal, overbore= torque, underbore = revs, it all equates to recipricating mass. Shorter the stroke the faster it can rev. not necessarily higher. Once again condensed as it is to long to type out entirely.

L.P.

[knighty]

contrary to whats said above, long stroke engines can be revved very high.......I should know as I have done it........in the 2001 BTCC we designed the Proton Impian 2.0 engine with a bore of 83mm (very small) and a stroke of over 90mm - quite long.......the base engine was actually a Renault 1.8 - but thats another story.......needless to say it produced bags of torque and had a comfortable 274Bhp at about 8000rpm.......rev limited to 8500rpm.......and in the chassis that was closer to 280bhp with the ram-air and cold intake air effect, as it drastically leaned out on the lambda readings when in the car........the general pit lane and autosport consensus was that the impian had the most powerful engine in the BTCC in 2001/2002 - it pulled like a train - all due to lots of torque and a long stroke motor........shame the impian chassis handled like a boat

Listers could have quite easily kept the standard stroke, and installed dry liners to reduce the bore size by a few mm......I calculated yesterday for 620bhp at they need 850Nm of torque, therefore with 725Nm they are 125Nm out.......

ideally wet liners are better for greater thermal contact with the coolant......pinching a few mm is normally quite do-able on the bore........you just need to be carefull that you dont shroud the valves too much........going smaller on the piston obviously makes it lighter, which helps high revving applications........calculating bearing loads is easy for me to calculate - so as long as you do not breach certain pressure limits for the main, big and small end shell bearings - dependant on their material type - all will and does work fine.

am still waiting for the new pescarolo pics - sorry for the off topic stuff paul

[AMT]

Originally Posted by knighty

thanks truckosaurus - interesting article - all is clear now......60mm throttle bodies ......silly boys.....as I suspected - they fell into the bigger is better trap......the inlet port velocity will be way too slow with a throttle that massive.........they need to be drastically smaller than that, like between 42 and 45mm - and be straight too, and aimed at the back of the valve head - not those horrid Kinsler bent things, must be a constant section shape too, they have gone from a round valve to a square flange face to round butterflys......the intake runner should be the same cross sectional shape all the way through - like ROUND!

the bore to stroke ratio is not particularly clever either........the bore is way too big - better suited for a high revving application, than the low revving endurance engine thats its supposed to be - they should have kept the bore and stroke about square........its way too over square with a 3.41" stroke and the 4"+ bore........

although it produces lots of torque - it should be producing more.........looks like it was designed on the back of a fag packet by a mechanic - deffo not a race engine design engineer effort.

Very perceptive. I don't think they ever got to grips with what was needed for the low peak-power revs resulting from the very small restrictors of the time. Otherwise, the package was good - the pumps were moved and the sump redesigned so that the installation was low and light.

But I think the 570bhp figure was optimistic...

[knighty]

Originally Posted by Rollcentre

Sounds like Knighty may be somebody I have given money to recently.....and if so, you do indeed know your beans on this subject Sir. Nuff respect!

Martin - I would just like to confirm that you deffo have not given me any money recently - but if you would like to - please do not hesitate look at my personal profile - particularly my occupation ;-)........

Now your obviously a well connected man with John Judd........if your allowed to talk about it - whats the progress of the Ricardo-Judd V10 DIESEL project......is it going anywhere?

and good luck for 07 - I have high hopes for your new ride.

[Rollcentre]

I thought you were Peter Knight, who did a great job on a 7 litre LS7 restrictor FIA GT2 motor for us for the Mosler. Pulls like a bloody train, and all the stuff you wrote about, airspeed, throttle body sizes etc etc, well it sounded just like Peter......

That engine dies a death once it gets close to 6000 rpm on the BHP, but the torque is unbelievable. Its all about maximising what you can get out of the air before the restrictor kicks in. And torque isn't hurt by the restrictor (excuse my racers lack of real knowledge here.....), so maximising that reaps dividends.

JJ's project on the diesel is very quiet I believe. It needs a manufacturer to keep the Cyborgs in beer and fags for them to head down that route I would think. Great company, and always realistic in what they can do with the funding thay have (us, their customers!).

Looking forward to getting the 5.5 Judd, but would love to see what a 6 litre LS7 derivative could do in LMP1. Just love those yank motors.....

[Hammerdown]

You beat me to it! I was just going to ask the engine chappy if a 6-litre LS7 would make a good P1 engine.

I would imagine it could be made fairly light and not having four cams, would also be lower than a DOHC design.

Would it also be eligible for a larger restrictor as it is a two-valve? I seem to remeber reading this in the GT1 regs.

Is a cross-plane less prone to vibrations than a flat-plane?

Come to think of it, how about the Aston 6-litre V12. With GT1 restrictors it pushes out about 600 I believe. Would the P1 restrictors be larger? I suppose you'd start getting into issues of length, weight and fuel consumption with a V12 though.

[knighty]

yup - I believe it will be possible to do a "budget" LMP1 motor using a yank 2-valve V8 - and yes - the noise is to die for - but like I was saying earlier some important things need to be considered and done correctly - the bore and stroke needs to be kept equal as a minimum - ideally a longer stroke than the bore size......reason being, the large crank stroke is the main factor that makes the big torque figures - simple physics really - to be in the region of the judd power - wich I have at 640bhp for the 5.0 V10 - a 6.0 yank V8 will need to be developing about 646 pound-foot of torque at 5200rpm (876Nm)........as long as it has a sensible stroke and a decent inlet system for high port velovities - those figures are quite do-able. for restricted engines you generally dont need a big valve and bore size - as its a restricted engine.......the valves will not let in more than the restrictor!........hence decent restricted engines are long stroke, small bore motors - F3 engines are a prime example of this.

as for the crank layout - probably better off keeping the cross-plane crank - to start with - although 25% heavier than a flat-plane - but investigating a flat plane crank is well worth the cost of the crank and associated camshaft - as it will make the engine drastically more responsive due to removing about 25% (10Kg-ish) from the rotating crank mass..........just need to be very carefull with crank related torsional vibrations - but there are now some very nice viscous crank dampers about, that I'm sure can fix any problems there.

the ACO regs state a 44.8mm restrictor for a 6.0 4v engine......but a 46.3mm for a 6.0 2v engine - so thats worth having! - the only real down side is the all up weight of the motor - it will never be on par with the likes of judd and zytecs motors.......but being a brick out house of a motor never hurt the Cosrowth DFV and HB......they dont weigh the motor then put you on the podium - its gotta last the distance.......a few years back, the old panoz did a decent job of taking on the R8.........

the following statement is very true too - " quoting power figures sells engines - torque wins races".......believe me - its very true..........your not going for the Judd 5.5 v10 for the extra 10bhp - its the drastic increase in torque - about 30% if I remember correctly.......not to mention lower revs therefore better reliability..........martin - let me know if you would like a full feasability study done.

[knighty]

just to add some weight to what I'm saying above about long stroke normally aspirated restrictor engines - heres the spec of the best F3 engine - the merc - as to be used by Carlin in 2007 (they are dumping NBE Honda)

Mercedes-Benz M 271 F3

bore =82.50 mm
stroke = 93.40 mm
1997 cm³
compression ratio 13.0 : 1
Ø 26 mm restrictor
around 154 kW / 210 HP at 6.000 rpm
around 265 Nm at 5.000 rpm

I have had a look at the LS7 engine specs and wow! - what a motor as standard - nearly fell off my seat when I read it has titanium con-rods and inlet valves.......anyway, standard bore is 104.8mm..........stroke is 101.6mm.......giving 7.0 litres........I have worked out this would require a reduced bore of 96.9mm for 6.0 LMP1.......assuming this would not touch the valves?........this is a nice region to be in with the bore to stroke ratio of 0.95.......but that would result in a poultry compression ratio of about 9.5:1 as the combustion chamber volume is a total of 87.64cc......... but I reckon if the head gasket was removed and replaced with wills rings, the head was skimmed to the max, the combustion chamber volume can be drastically reduced, and over 12:1 compression ratio could be achieved quite easily - without having to resort to massive piston intruders whick kill power.........deffo worth looking into further if anyone wants to provide me with more engine details!

[paul-collins]

knighty, that's cool stuff.

[The Badger]

Originally Posted by The Badger

Why not try and get their hands on a Katech C6R engine ?

Cant if be sleeved down ?

[The Badger]

[QUOTE=knighty]Martin - I would just like to confirm that you deffo have not given me any money recently - but if you would like to - please do not hesitate look at my personal profile - particularly my occupation ;-)........QUOTE]

Hey hey ..... Martin , never mind knighty ..... gimme some too !!!

[The Badger]

Originally Posted by knighty

but that would result in a poultry compression

Whats "poultry" compression ?

Is that when you stamp on a fowl or what ?!

[knighty]

Originally Posted by The Badger

Whats "poultry" compression ?

Is that when you stamp on a fowl or what ?!

ok smarty pants - I should have said "poor compression ratio" - apologies for my queens english - you will have to let me off - I am from essex you know - we do struggle a bit down here - innit

Just been on Mikes website and found interesting info about the elan power products Panoz 6.0 2v V8 motor used in the old Panoz LMP900.......620bhp @ 7200, and 538lb/ft @ 6500, with 2 x 33.1mm restrictors - the same as specified today.......aparrently it weighed.....wait for it.......198Kg.......CRIPES!.......but that didnt stop it making the R8 blush on many an occasion........cant seem to find the bore and stroke anywhere though

[chernaudi]

Well, the Elan V8 was based on what was then a 30+ year old design-the pushrod OHV crossplane Ford 351 V8. It's the all aluminum SVO variant to be exact-uses Cleveland cylinder heads and a Windsor block. The Panoz didn't exactly make the Audi boys blush-and I was(and still am) a Ford guy long before I became an Audi fan. The Panoz was kinda the wrong platform long term for the engine-it wasn't bad, but it became outdated fairly quickly in the areo department. The car handled well though(near equal f/r weight distribution).

I don't know the exact bore/stroke for the EPP engine, but the orginal for the 351 was 4x3.5 in(about 102x88 mm), which equals 5763 cc/351.7ci.

[HORNDAWG]

That would be a Cleaver!!

L.P.

[chernaudi]

Actually the 351 Ford engines, be it Cleveland, Windsor, or SVO, share the same bore and stroke, and thus capacity. In fact, that's about all they share(asking an expert on Ford engines will point out all differences), but a major difference is the deck height-and it's different for all the engines.

[gwyllion]

The Pescarolo livery will be blue: http://www.endurance-info.com/articl...d=3447&thold=0

Do not confuse it with the Rollcentre livery: http://www.ultimatecarpage.com/pic.p...=1&carnum=3187 Shorty should really add some green to his car.

Kruse did a rollout of the LMP2 Pesca: http://www.projectlemans.de/content/view/2970/1/ Their livery will be white, red and black: http://20832.com/misc/2007/Siegerdesign.jpg

[WouterM]

That's gorgeous. It's very Matra indeed.

[Bentley03]

Very smart indeed!

I assume the other car will have green highlights instead of the red..........

[vorsprung]

Looks nice and good to see that they've gotten sponsorship from Morgan enthusiast Sturdza's company.

To me the front fender shape of Pesca has always seemed a bit "heavy" and it looks especially bad on the pure white Kruse car.

[The359]

I don't like it as much as the Pescarolos of old, the red on blue isn't a pleasing match.

[jhansen]

Yeah, I agree with 359. The Pescarolo has looked pretty good the last few years. The blue isn't too bad though. With that said, if I were Playstation I would not be very thrilled. Their name doesn't exactly stand out.

[The359]

I do notice Gran Turismo HD now adorns the rear wing.