The V8 Owners Forum -

This is the published spec of a modified S1 SD1 and I wondered if anyone would like to comment?


Reworked P6B engine block.
Crankshaft standard new, fitted with selected and matched standard conrods.
Compression ratio 12.1
Cylinder heads fully reworked.
Standard size waisted stem rim flow inlet valves.
Waisted exhaust valves, standard size.
Boxer inlet manifold, fitted with 4x CD175 carburettors and cruise control.
2x 5 ¾” K+N Air cleaners.
224 Cam shaft, lift inlet .490”, exhaust .520”.
Hi rev hydraulic lifters, G.M. lightweight competition push rods.
RS single competition springs, standard rockers.
Exhaust S+S stainless steel 4 into 1 headers into Y section with S+S through pipe with 2 open silencers.
Emission controls, full air pump system into exhaust ports, closed engine breathers and fully closed fuel system as to U.S. fed spec.
Fuel, 95 octane, lead free.
Gearbox, standard 5 speed with full synthetic lubrication.
Rear axle ratio 3.45.1.
3rd gear max 7000 rpm, 120 mph.
Suspension, front wheel camber -3 degrees, lowered and up rated springs and SPAX gas top adjustable dampers with urethane anti roll bar bushes.
Rear suspension, A.E.C. trailing links with urethane bushes, A.E.C. watts linkage with urethane bushes, uprated and lowered springs with SPAX adjustable gas dampers 4” ride height.
Brakes- front 4 pot Jaguar callipers and drilled discs, rear has uprated shoes. its 0-60 was timed at 5.5sec and its top speed was 165mph

Any photos? Pretty quick for a 3.5. Wonder why a P6B block. 12.5 CR is high for 95 octane. Interesting it's still running full emissions with air pump. This was the first thing that you used to remove on the Aussie spec 'detoxed' SD1s.

What intrigued me was the claimed top speed. And how much 'power' would be needed to achieve this.

DaveEFI wrote:What intrigued me was the claimed top speed. And how much 'power' would be needed to achieve this.

120mph is intriguing? Hell, my old '68 MGB would see over 100mph with the wheezy 1.8 boat anchor. Surely 120 is pretty easy for a V8 SD1? Might need a long run and be downhill, but plenty of motorways for that

chodjinn wrote:

DaveEFI wrote:What intrigued me was the claimed top speed. And how much 'power' would be needed to achieve this.

120mph is intriguing? Hell, my old '68 MGB would see over 100mph with the wheezy 1.8 boat anchor. Surely 120 is pretty easy for a V8 SD1? Might need a long run and be downhill, but plenty of motorways for that

That was in 3rd gear at 7000 rpm.

The claimed top speed is 165 mph. Most modern saloons of this size with a genuine top speed of 165 mph tend to have a great deal of power - and likely a better coefficient of drag. So I was curious about how much would be needed to get an SD1 to that sort of speed.

FWIW, a top speed should be the mean of two runs in opposite directions on the same bit of road. Not what it can achieved going downhill - or when being dropped out of an aircraft.

165mph in an SD1, hah!

An old guy on Passion Ford gave me this formula (his old sierra does well over 200 mph!)



So if a Rover Vitesse does 135mph with 187 bhp

165/135 = 1.222222222

1.222 x 1.222 x 1.222 = 1.825

1.825 x 187bhp = 341 bhp

Assuming my maths is OK

The maths is good as wind resistance goes up with the cube of speed.

Two points occur on the engine spec:
1 - Boxer manifold - I would avoid that like the plague.
2 - 95 octane fuel + 12:1 compression ratio. I guess that is a US octane number... as 95 surely would pink like mad.

Also I guess the reworked P6 block is due to a scarcity of SD1 blocks, as certainly the later SD1 blocks are stiffer and hence better.

Chris.

Mark wrote:An old guy on Passion Ford gave me this formula (his old sierra does well over 200 mph!)



So if a Rover Vitesse does 135mph with 187 bhp

165/135 = 1.222222222

1.222 x 1.222 x 1.222 = 1.825

1.825 x 187bhp = 341 bhp

Assuming my maths is OK

Would that be Mad Rod by any chance?? I think his Sierra has around 700-800 +hp on tap


My Stock MGB GT with the original Rover 3500 V8 made 147mph with a 150 shot of nitrous on the go behind a mates Ex police Volvo T5 estate using him as a wind break. I cut the run off at 147 mph because the old girl felt like she had no more and she was about to get airborn... ??

Unless it has huge tyres, it aint doing 120 in 3rd even at 7k...

And how common is it for RV8's to pull 7k ?

If anyone wants to work it out

Standard:-

Tyres 195/70 14
Final drive 3.08:1
3rd gear 1.396:1

I make it would be pulling 119.8 at 7000rpm

r2d2hp wrote:I make it would be pulling 119.8 at 7000rpm

Yup. I worked that out too:-


Tyres 195/70 14
Final drive 3.08:1
3rd gear 1.396:1

So (working (ish) to the nearest whole number):-

Engine RPM to RPH

7000 x 60 = 420,000 engine revs per hour

Divide by gear and axle ratios gives 97,682 wheel revolutions per hour

Circumference of a 195/70 14 is 1975mm.

So car will travel 192,922 metres in an hour.

192,922 metres is 119.9 miles.

Comparison time here
I have my Rover 3.9 in my Dax Gt40

It is a John eales built engine and balanced wetc so good for 7000 rpm

I have had it on 2 dynos and they are about 6hp apart so a little over 250hp or a little under

Dax is 1100kg Vs SD1 ???
Dax is 42 inches high SD1 ????
Dax frontal area is fairly small SD1???


On Le Mans Malsane straight between Tetre Rouge and first chiccaine I have been the fastest I ever got
Through the Tetre Rouge corner at about 65mph

Up through gears and last saw speedometer at a bit over 140mph (About 5150 in 5th) them I watched where I was going because she got very light on the front end
Revs continued to rise to around 5500 - slightly over 150mph when I hit the brakes because of a queue at the chiccaine

I doubt I could have got more than 160mph without a lot more road and my balls aren't big enough as she was floating too much.

Question for Stevie what HP were you generating on the 202mph run?
Ian

Maths is all good, but it lists 3.45 diff

It is not doing 120mph in 3rd

Power ? Haven't a clue, not enough.

Prob more now, but still a lack of rpm's available. Will rectify that over the winter.

SD1 isn't a bad shape, so don't see 160+ as that unrealistic, if it has the power matched to gearing and enough distance