9 replies to this topic

[slon001]

Hi There, I'm trying to find more information about the design (specificically valvetrain geometry) for the 1994 Mercedes / Ilmor 500i pushrod engine designed under the 'stockblock' rule for the indy 500.

I recall reading a technical article quite a few years ago, but searches recently have not turned up much at all.

Any input welcome as to where to find out more about this interesting engine.

Thanks,

Simon

[McGuire]

There is a very nice chapter on the engine in Karl Ludvigsen's recent and excellent book on racing engines... the exact name of the title escapes me at the moment, but Amazon should turn it up easily.

[Engineguy]

The very first issue of Race Engine Technology, if you happen to have it, may be where you saw the article... and I think it may have been by the aforementioned Mr. Ludvigsen. I know I have it, but I can't find it at the moment. Gotta get my "library" organized.


RACE ENGINE TECHNOLOGY 001 SUMMER 2003

CLASSIC ENGINE: MERCECES-BENZ 500I
Inside the ultimate Indianapolis pushrod V8

[slon001]

Great - thanks for the prompt help there. I've tracked down and ordered both of those sources, so should be on the right track.

Any other info greatfully accepted.

Thanks again.

[McGuire]

I believe the two sources are very similar if not identical.

[Engineguy]

Originally posted by McGuire
I believe the two sources are very similar if not identical.

I suspect you may be right, but he probably won't be too disappointed... the first issue, as with most periodicals, of RET was probably the thickest, with lots of other good stuff, and the book is great too... the only criticism is it is so interesting it leaves you wanting more.

[McGuire]

Agreed, both are well worth having.

[J. Edlund]

Some specs from the RET article

Cylinders: V8, 72° bank angle
Cylinder centres: 109 mm
Bore: 97.0 mm
Stroke: 58 mm
Stroke/bore ratio: 0.60:1
Capacity: 3,429 cc
Compression ratio 11.0:1
Connecting rod length: 116 mm
Rod/crank radius ratio: 4.0:1
Main bearing journal diameter: 58.0 mm
Rod journal diameter: 50.0 mm
Inlet valve diameter: 52.5 mm
Exhaust valve diameter: 39.7 mm
Inlet pressure: 1.86 Atm
Engine weight: 290 lb / 136 kg
Peak power: 1024 bhp @ 9800 rpm
Maximum speed: 10,400 rpm (10,000 rpm for the 500)
Piston speed (corrected): 4823 ft/min / 24.1 m/s
Peak torque: 557 lb ft / 755 Nm @ 8000 rpm
Peak bmep: 402 psi
Engine bhp per litre: 298.6 bhp/litre
Engine weight per bhp: 0.28 lb/bhp / 0.13 kg/bhp

Valve timing
IVO: 87° BTDC
IVC: 87° ABDC
EVO: 84° BBDC
EVC: 84° ATDC
Inlet lift: 15.7 mm
Exhaust lift: 14.4 mm

Aluminum block and heads. Block ends at crank centre, bedplate design where the lower crankcase casting forms the main bearing caps and dry sump. Four main studs per main bearing. Wet steel liners gooved for solid sealing ring, flange at the top. Five main bearings. 180 degree billet steel crank, four counterweights with screwed in tungsten plugs. I-profile steel connecting rods. Single camshaft in block driven though gears with a pendulum type damper in the nose. The rear end of the cam drives a scavenge pump for the single Garrett TA74 turbo. The cam rotates in four caged roller bearings on 45 mm journals and a ball bearing in the front. Each head is attached by ten studs. Short skirt slipper type pistons with three rings and a steel piston pin. Inclined two valve chamber rotated 20° from transverse. 10° inlet valve angle and 13° exhaust valve angle. Dual coil springs, titanium valves and retainers, copper alloy seat inserts. Pivoted finger type roller followers. Stainless steel push rods and roller rockers. Lift multiplication ratio of 2.175:1.

[MrAerodynamicist]

There's also the book Prime Movers: Ilmor and Its Engines (Hardcover) by Karl Ludvigsen (Author), although I don't know how much technical detail it'll go into.

[McGuire]

Originally posted by J. Edlund
Lift multiplication ratio of 2.175:1.

As slon101 identified, the valvetrain geometry is one of the more interesting aspects of this engine. There are two sets of rocker arms, one at the valve and the other at the camshaft, with needle bearings everywhere including the camshaft journals. This thing had an enormous 52.5mm (2.06 in.) intake valve and they were lifting it 15.7mm (.618 in.) at 10,000 rpm... that is in the realm of the possible today, but this was 1994.