WWW 
Haku
Jäsenet
Kalenteri
Apuja
Portaali
28-07-2010, 04:01
http://www.roversd1.nl/sd1web/index.html
hyvää infoa kuinka B-ryhmäläisiin ympättiin 3,5 litran V8 pätkäistyä V6 konetta... :roll:
eli tuolta sivuilta racing -> winged wonder ja sieltä pitäsi löytymän
Wha tever else one may say about what is now the definitive car, there was never an MG like the 6R4, sorry, MG Metro 6R4. What, it is now obvious, was the firstthoughts four-wheeldrive rally prototype, powered by a mule V6 made by cutting and shutting a 3.5-litre Rover V8. has changed tremendously.
The biggest difference is the specially designed and built four-camshaft 24-valve normally aspirated 3-litre V6 which, as originally promised, is no relation of the GM-originating Rover or the coming Honda V6 of Project XX. That ex-Rover 2.5-litre V6 was said to turn out 320 bhp.
The new 3-litre is capable at the moment of up to 410 bhp at 9000 rpm. As is increasingly so with most of Austin Rover's future rivals, the pretences of what are really silhouette racers are thinner than ever, with even less of the first thin skim of Metro, and the differences are compounded by the most overt aerodynamic aids yet seen in a Group B rally car.
Early experiments were with the cut-down Rover V8 with its 90 deg. block. Wood says these led to the replacement of the cut and welded Rover block with a specially cast block, and thence (after acknowledging that the 1.25 to 1 Rover bore to stroke ratio and 2.5-litre capacity were restrictive) to the final completely new design which, however, retained the 90 deg. V rather than the 60 deg. nearer ideal for a V6.
On the `International' or full rally version, the crankshaft is machined from solid En 40b where the same size `Club' one is also fully machined but from a part forging. One balances such a crankshaft as three separate 90 deg. V-twins as far as primary (reciprocating) forces, which leaves just the secondary imbalance to deal with.
The crank is thus kept short and stiff, with 2.23in diameter main bearings and 2.23ín dia by 1.7ín wide crank journals to minimise the effects of the secondaries with a three crankpin layout, and does not need any crank damper. Each crankpin bas two'5/8in dia bores to lower weight. To reduce the considerable power needed at top revs to drive the feed oil pump of the dry sump system, the crankshaft oilways are drilled eccentrically, close to the journal surface, so that the pump only has to counter roughly 1/4in of radical passage to force oil inwards against centrifugal force into each longways drilling.
The rally connecting rod is a thing of mechanical grace, with its deep, slender webs and shotpeened finish the 0.866ín dia gudgeon pin is fully floating, circlipheld in the three-ring Mahle slipper piston whose slightly domed crown is deeply recessed for valve clearance in a 12-to-I compression ratio space.
Deep clearances are necessary because of the comparatively high valve lift on the rally engine 0._512ín or 13mm (against 0.413m or 10.5mm for the Club).
Returning to the cylinder block, its skirts are continued well below the crank centreline to be further stiffened by the necessarily stronger than usual cast sump which has to sustain some transmission loads from the rear final drive bolted partly to its right hand rear (as mounted in the car) face, and partly to the corresponding face of the block, and the nearside drive shaft coupling on the end of the tubular 1-1/4in dia fixed shaft which runs across the sump in a cast tube under the rearmost main bearing cap.
Cylinders are dry cast iron liners.
Flexible output
The claimed maximum power output is 410bhp at 91O0 rpm in tarmac tune, with 270lb ft of torque at 6500rpm the alternative state in loose surface tune of 380 bhp at 8500 rpm is obtained with longer intake trumpets and altered camshaft timing. Beside the differences already mentioned.
The Club engine has different pistons, valve springs, camshafts and inlet manifolding the last is a conventional V-engine type one associates with a central carburettor, except that its single combined intake carries only a throttle butterfly to feed the multi-injector system.
This milder tuned engine still delivers a claimed 250 bhp at 7000 rpm and 225lb ft at 4500 rpm.
One does not associate engines delivering a claimed specific output of over 130 bhp per litre to be flexible. Yet that is exactly what this engine is designed to be. relatively speaking. Its makers claim that in the top performance form, it is already delivering 230 1b ft 85 per cent of the peak figure at as low as 3500 rpm. without dropping below that level until after 9000 rpm. 500rpm before the maximum safe engine speed (which is guarded by an electronic cut-out).
This is partly thanks to what sounds like good porting and combustion. but also to the comparatively generou, valve lift and the valve timing the inlet opening 52deg b.t.d.c.. shutting 72deg a.t.d.c., exhaust opening 74deg b.b.d.c. and shut-ting 50deg a.t.d.c., ;giving 304 deg of total inlet opening period. Corresponding figures for the Club camshafts are 20-52-52-20, riving a 252 deg period.
hyvää infoa kuinka B-ryhmäläisiin ympättiin 3,5 litran V8 pätkäistyä V6 konetta... :roll:
eli tuolta sivuilta racing -> winged wonder ja sieltä pitäsi löytymän
Wha tever else one may say about what is now the definitive car, there was never an MG like the 6R4, sorry, MG Metro 6R4. What, it is now obvious, was the firstthoughts four-wheeldrive rally prototype, powered by a mule V6 made by cutting and shutting a 3.5-litre Rover V8. has changed tremendously.
The biggest difference is the specially designed and built four-camshaft 24-valve normally aspirated 3-litre V6 which, as originally promised, is no relation of the GM-originating Rover or the coming Honda V6 of Project XX. That ex-Rover 2.5-litre V6 was said to turn out 320 bhp.
The new 3-litre is capable at the moment of up to 410 bhp at 9000 rpm. As is increasingly so with most of Austin Rover's future rivals, the pretences of what are really silhouette racers are thinner than ever, with even less of the first thin skim of Metro, and the differences are compounded by the most overt aerodynamic aids yet seen in a Group B rally car.
Early experiments were with the cut-down Rover V8 with its 90 deg. block. Wood says these led to the replacement of the cut and welded Rover block with a specially cast block, and thence (after acknowledging that the 1.25 to 1 Rover bore to stroke ratio and 2.5-litre capacity were restrictive) to the final completely new design which, however, retained the 90 deg. V rather than the 60 deg. nearer ideal for a V6.
On the `International' or full rally version, the crankshaft is machined from solid En 40b where the same size `Club' one is also fully machined but from a part forging. One balances such a crankshaft as three separate 90 deg. V-twins as far as primary (reciprocating) forces, which leaves just the secondary imbalance to deal with.
The crank is thus kept short and stiff, with 2.23in diameter main bearings and 2.23ín dia by 1.7ín wide crank journals to minimise the effects of the secondaries with a three crankpin layout, and does not need any crank damper. Each crankpin bas two'5/8in dia bores to lower weight. To reduce the considerable power needed at top revs to drive the feed oil pump of the dry sump system, the crankshaft oilways are drilled eccentrically, close to the journal surface, so that the pump only has to counter roughly 1/4in of radical passage to force oil inwards against centrifugal force into each longways drilling.
The rally connecting rod is a thing of mechanical grace, with its deep, slender webs and shotpeened finish the 0.866ín dia gudgeon pin is fully floating, circlipheld in the three-ring Mahle slipper piston whose slightly domed crown is deeply recessed for valve clearance in a 12-to-I compression ratio space.
Deep clearances are necessary because of the comparatively high valve lift on the rally engine 0._512ín or 13mm (against 0.413m or 10.5mm for the Club).
Returning to the cylinder block, its skirts are continued well below the crank centreline to be further stiffened by the necessarily stronger than usual cast sump which has to sustain some transmission loads from the rear final drive bolted partly to its right hand rear (as mounted in the car) face, and partly to the corresponding face of the block, and the nearside drive shaft coupling on the end of the tubular 1-1/4in dia fixed shaft which runs across the sump in a cast tube under the rearmost main bearing cap.
Cylinders are dry cast iron liners.
Flexible output
The claimed maximum power output is 410bhp at 91O0 rpm in tarmac tune, with 270lb ft of torque at 6500rpm the alternative state in loose surface tune of 380 bhp at 8500 rpm is obtained with longer intake trumpets and altered camshaft timing. Beside the differences already mentioned.
The Club engine has different pistons, valve springs, camshafts and inlet manifolding the last is a conventional V-engine type one associates with a central carburettor, except that its single combined intake carries only a throttle butterfly to feed the multi-injector system.
This milder tuned engine still delivers a claimed 250 bhp at 7000 rpm and 225lb ft at 4500 rpm.
One does not associate engines delivering a claimed specific output of over 130 bhp per litre to be flexible. Yet that is exactly what this engine is designed to be. relatively speaking. Its makers claim that in the top performance form, it is already delivering 230 1b ft 85 per cent of the peak figure at as low as 3500 rpm. without dropping below that level until after 9000 rpm. 500rpm before the maximum safe engine speed (which is guarded by an electronic cut-out).
This is partly thanks to what sounds like good porting and combustion. but also to the comparatively generou, valve lift and the valve timing the inlet opening 52deg b.t.d.c.. shutting 72deg a.t.d.c., exhaust opening 74deg b.b.d.c. and shut-ting 50deg a.t.d.c., ;giving 304 deg of total inlet opening period. Corresponding figures for the Club camshafts are 20-52-52-20, riving a 252 deg period.