Bore and stroke on early 2000,s V10 engines

[ACRO]

the internal dimensions were a state secret at the racing times of these engines, now we have some more insight , but not at at all the details .

generally there was a battle for revs at that times so we saw all engines a bigger and bigger bore and a shorter and shorter stroke from the given displacement in early 2000,s .

the downside of this was physically a problem to reach a high compression ratio and to maintain a good combustion .

another aspect was - a larger stroke physically helps in midrange torque but limits top end power since piston speeds vs material strenght set a limitation on this . ilmor did a trick with berrylium so it appers ( but not confirmed ) they since 1998 always ran smaller bore / bigger stroke than other top teams and had better midrange torque but thanks to pistons out of berrylium they nevertheless were able to run the same rpms and power levels like e.g ferrari . 2001 they were doomed with this concept and the prohibition of berrylium .

looking at the 2001 season i have following data from different sources

(all in millimeters ):

BMW : 95x42.3
Ferrari : 96x41.4
Asiatech : 91x46.1
Honda : 95x42.3
European Minardi : 89x48.1
Sauber / Prost : 96x41.4

i do not have any reliable data for the ilmor-mercedes , i heard rumors it was
94x43.2 but not confirmed

and also do not have any data for the cosworth jaguar and no data for the renault engine - does anybody has ?

best regards !

[saviour stivala]

3.5-litre V10 engines of 1992:-
Ilmor V10 had a bore of 86.6mm (stroke/bore ratio 0.69:1).
Judd V10 had a bore of 93mm (stroke bore ratio 0.55:1).
Renault V10 had a bore originally of 90mm and then enlarged to 93mm.
3.0-litre V10 engines of 1995:-
Bore sizes being used were from 87mm to 93mm.
By 1998 with engine speeds circa 17000rpm the above bore sizes progressed to 90mm to 96mm.
By 2003 with engine speeds above 18000rpm the bore sizes were 92mm to 98mm.
The year 2000 FERRARI tipo 049 90 degree V10 (2997CC) had a bore of 96mm a stroke of 41.4mm a bore/stroke ratio of 0.43:1 a compression ratio of 12:1 valve sizes of 40.4mm intakes 33mm exhausts an intake valve area of 35.4% of bore area, intake valve lift of 15.5mm exhaust valve lift of 14.1mm a max rpm of 18000. A firing order of 1-10-5-6-2-9-3-8-4-7. Number I cylinder right side front, number 6 cylinder left side rear.

[wuzak]

The V8s of 2006 were limited to a maximum bore of 98mm, so we can presume that at least one manufacturer was at that bore already.

[saviour stivala]

The 3.0-litre V10 era heralded a race for ever higher engine RPM as the fastest way forward in achieving ever higher outputs. The higher the RPM the bigger the bore, the bigger the bore the smaller the stroke. During this period both small bore and big bore sizes were used. When engine outputs reached 900BHP@the 19000RPM, 98mm bores and 39.8mm stroke were used. In 2006 a 2.4-litre 90 degree V8 with a maximum bore size of 98mm was mandated, this mandated maximum bore size 98mm which all those running their 3.0-litre V10’s at 19000RPM were using, was carried over to the 2.4-litre V8’S as all V8 were racing past the 19000RPM mark. Both the 98mm bore 3.0-litre V10’s and the 98mm bore 2.4-litre V8’s used 39.8mm stroke, which means both were using the same 300cc size cylinder capacity.

[saviour stivala]

As regards Ilmor and then Illmor-Mercedes Mario Ilien only ever disclosed the Ilmor Indy engine and his Formula 1 3.5-litre 2175A 72 degree bank angle V10 bore sizes, otherwise his 3.0-litre V10's used by McLaren and paid for by Mercedes as well as his 3.0-litre V10's branded 'Mercedes' (F0110F, F0110J) the bore and stroke as well as the number of main bearing used were always marked in his specification as "undisclosed".

[ACRO]

very nice comments !

i know honda went 97mm bore in 2002 or 2003 and stayed there until introduction of the v6 .

i would love to see what bore renault had at the introduction of their 111deg V10 , never found any information .

in any case i,m fascinated with the development of 2000-2008 . there was nothing more to do in increasing volumetric efficiency / torque from an atmo engine. the only way to go for power were rpm,s and we saw the most extreme bore to stroke ratios ever in a piston engine . the hottest motorcycle engines of today are far away from the bore - stroke ratios they went in f1 .

[Nonserviam85]

BMW started with a bore of 94mm and increased it to 98mm for the 2005 with the last V10. After that with the V8 they kept the maximum this size which was the maximum allowed by the rules. The rules also mandated a 95kg minimum weight and a minimum centre of gravity which made the design simpler and robust, BMW claimed they could have built a 65kg V8 if they kept the P85 engine concept and developing it.

[saviour stivala]

Bore size and bore/stroke ratio for a given capacity is the heart of the matter. The precursor of the 3.0-litre V10 was the Coventry Climax FWMV 1.5-LITRE V-8 engine (stroke/bore ratio 0.95:1) which in 1961 was one of the first of a new generation of formula one engines designed specifically to run on pump petrol. Reference:- SAE paper by Walter Hassan. The Cosworth DFV 3.0-LITRE V-8 (stroke/bore ratio 0.76:1) (in its original guise) of 1967 like the Hassan FWMV championed the merits of a relatively long stroke. In its ultimate DFY guise its stroke/bore ratio had fallen to 0.65:1. Then came the 3.5-litre HB V-8, which had a stroke/bore ratio of0.67:1. The XB V-8 Indy car 2.65-litre turbo went to genuinely short stroke of stroke/bore ratio 0.54:1. The world had changed by then, when formula 1 and Indy car engines were running to 13000 RPM to be competitive. The Renault V10 that dominated 1992 had a stroke/bore ratio 0.55:1. The bore had to make room for the valves large enough to run at such speeds. In 1994 Cosworth V8 moved the 94mm bore of its HB to 100mm and a compression ratio of 13:1. In general terms a large bore provides a lower piston speed for a given crankshaft speed and offers a potential for greater valve area. A smaller bore engine can reach a higher level of RPM before speed of flame propagation becomes a concern, it also makes for a better surface area/volume ratio and an inherently cleaner chamber shape. The big bore Cosworth EC V-8 needed an engine management system specifically to run this bore size :-“we couldn’t have done it with mechanical injection” (designer Martin Walters) but on the other hand the shorter stroke implied stiffer crankshaft, particularly significant at a time when the journals were shrinking in size to counter spiraling bearing losses.

[ACRO]

yes bmw started with a 94 bore in 2000 but i assume they realized they need to go higher . 95 in 2001

ferrari went 2000 with a 96 bore but did not had the most powerful engine in 2000 and 2001 - i think they have fought lowering volumetrics at this short stroke

it was designing on the edge . going bigger bore and so shorter stroke resulted in trouble reaching high compression and good volumetric efficiency .

keeping the bore lower and stroke higher limited the rpm,s . we talk about an millimeter difference .

[Nonserviam85]

The main focus actually was to increase rpm and reduce weight, I don’t seem to remember that the compression ratio and volumetric efficiencies to be as crucial back in the day.

[saviour stivala]

94mm bore, 3.5-litre V8 compared to 94mm bore, 3.0-litre V10.
3500cc v8.:- bore 94mm. stroke 63mm. stroke/bore ratio 0.67. maximum RPM 13000. peak power RPM 12500. BHP 720.
bmep (BAR) 14.7. Cc/cylinder 437. BHP/cylinder 90. mean piston speed (m/s) 27.2@13000RPM. maximum piston acceleration (ft/s) @13000RPM 236.866.
3000cc V10,:- bore 94mm. stroke 43.2mm. stroke/bore ratio 0.46:1. maximum RPM 19000. peak power RPM 18500. BHP 900. bmep (bar) 14.5. Cc/cylinder 300. BHP/cylinder 90. mean piston speed (m/s) 27.3@19000RPM. maximum piston acceleration (ft/s) @19000RPM 347.293.

[Tommy Cookers]

the examples in the above post seem perversely chosen to have a common piston speed - to suggest what ?
the HB V8s low piston acceleration shows it's able to reciprocate much faster than 13000 rpm (given pneumatic valves etc)
that's how the series VI first peaked at 13500 rpm, then 14000 rpm
and ....

...a larger stroke physically helps in midrange torque but limits top end power since piston speeds vs material strenght set a limitation on this . ilmor did a trick with berrylium so it appers ( but not confirmed ) they since 1998 always ran smaller bore / bigger stroke than other top teams and had better midrange torque but thanks to pistons out of berrylium they nevertheless were able to run the same rpms and power levels like e.g ferrari . 2001 they were doomed with this concept and the prohibition of berrylium ....

well yes but ....
force is proportional to piston acceleration not to piston speed
ie safe rpm is (inversely) proportional to square root of stroke not to stroke
piston speed isn't a hard limit on engine rpm - but piston acceleration is

[e36jon]

I know in the road-car based world having the rings coming off the lands at the top of stroke when the piston reversed direction was one of the limiting RPM cases. I have seen the rings for the Cosworth TJ V10 and they don't look like anything resembling rings as they are so thin and narrow.

Mudflap has a Cosworth TJ V10 piston article on here and someone supplied FEA to match viewtopic.php?f=4&t=27814&hilit=cosworth+tx+piston. Turns out that they were up against the center of the piston crown fatiguing due to flex under the same condition. Wow. I never heard of a similar issue in any other racing class.

Fun to reflect on how crazy this all got before the end.

[saviour stivala]

1993 3.5-litre power outputs:-.
Renault V10 790BHP. FERRARI V12 740BHP. Lamborghini V12 740BHP. Ilmor V10 735BHP. Cosworth V8 730BHP. Cosworth V8 customer 715BHP. Mugen V10 710BHP. Yamaha V10 710BHP. Hart V10 690BHP.
1994 3.5-litre power outputs:-.
FERRARI V12 815BHP. Renault V10 770BHP. Mugen V10 760BHP. Yamaha V10 745BHP. Ilmor V10 740BHP. Cosworth V8 730BHP. Peugeot V10 720BHP. Hart V10 710BHP. Cosworth V8 customer 680BHP.
2002 3.0-litre power outputs:-
BMW V10 880BHP. Toyota V10 850BHP. FERRARI V10 850BHP. Cosworth V10 845BHP. FERRARI V10 customer 830BHP. Renault V10 820BHP. Cosworth V10 customer 820BHP. Ilmor V10 810BHP. Honda V10 810BHP. Asiatech V10 780BHP.
2003 3.0-litre power outputs:-
BMW V10 910BHP. Honda V10 900BHP. Toyota V10 890BHP. FERRARI V10 885BHP. Ilmor V10 875BHP. Cosworth V10 870 BHP. FERRARI V10 customer 855BHP. Renault V10 850BHP. Cosworth V10 customer 845bhp. Cosworth V10 customer 830BHP.
2004 3.0-litre power output;-
Honda V10 930BHP. BMW V10 915BHP. Toyota V10 915BHP. FERRARI V10 915BHP. Ilmor V10 905BHP. Renault V10 880BHP. Cosworth V10 880BHP. Cosworth V10 customer 840BHP.

[saviour stivala]

Compression ratio:- The higher the revs the bigger the bore and the shorter the stroke. The bigger the bore the bigger the valves (the need to maintain at least 35% valve area ratio to piston area) the bigger the valves the bigger the valve-lift. To avoid recessing the valves in the head necessitates big valve pockets in top of pistons, these valve pockets represent the biggest portion of the combustion space. A 94-96mm bore high revving engine will be unlikely to have a compression ratio higher than 13:1. In fact no formula 1 V10 ever had. 13:1 was reported as the normal figure, and that if the compression ratio approached 14:1 there would almost certainly be too much compromise in terms of other factors, such as chamber form. One thing that was not inherently a challenge for such engines at the time, was the avoidance of detonation that was simply because it wasn’t feasible to attain the compression ratio level at which detonation will occur (JOHN JUDD) designer/builder of ‘Yamaha’ 1993 OX10A 3.5-LITRE V10. 1994 OX10B 3.5-LITRE V10. 1995 0X10C 3.0-LITRE V10. 1996 OX11A 3.0-LITRE V10. 1997 OX11C AND D 3.0-LITRE V10. The only engines in the V10 era to have no head to block gasket and head to block hold down bolts as screw-in cylinder-head liners were used resulting in the smallest and lightest engine at its time.
1997 Mario Illien:- “The shape of the piston crown is crucial, if you are not carful you have this shallow disc as a combustion chamber and that is not the best way to burn the mixture. At the same time you want to have some compression ratio”.
John Judd:- “Lacking operating time, probably lacking tumble and certainly lacking compression ratio, If you are past the 13:1 compression ratio the chances are that you have a bore size too small or your valve lift insufficient. The ignition advance for 16000RPM V10 are around 50 degrees BTDC.