The 'E' Type Forum

I am the "technical manager" of my friend's S1 4.2. It has fallen upon me to take care of the car from a technical / maintenance perspective.

When he approached me to do so, I had ONE condition: That the distributor be upgraded with a 123 Ignitions Bluetooth distributor - which I did first time I touched the car.

The car has again been with me for the last few days to have a few minor issues attended to and I've been driving it a bit (mainly to test the robustness of the cooling system - we are moving into summer now).

The more I drive it, the more it blows me away! Yesterday and today, I drove it a bit more enthusiastically as my confidence in the cooling system grows but JEEPERS!!!! Does this thing GO!!! I have always believed that my own , well tuned V12, would have the S1 covered, but the more I drive the S1, the less sure I become!! In the hands of a really competent driver the S1 must be competent weapon.

The S1 just feels so much lighter and so much more nimble! Very VERY impressive!!

Not too much of a surprise. The 4.2 and the S3 engines are nearly the same HP, but the S3 weighs 500lbs more.

Hi Philip

The S1 is indeed very impressive. Although I haven't driven a 3.8 myself (nor a S3, although I have driven a 4.2), I have spent plenty of time as a passenger in both types of S1. To me at least, they're are notably different in feel. Whilst the 4.2 has more low-down torque and seems a little more forgiving when bumbling along, my friend Richard's 3.8 is far more sporty/racy. It gives an almost turbine-like noise as it accelerates up through the rev range and immediately puts a smile on your face! It seems as though is 3.8 is faster than his 4.2 was. It does also rev 500 RPM higher so it always seems to have a bit more "go" about it.

Cheers

Simon

Philip you are touching on a nerve of mine and it regards weight and mass. I grant there is a trade off between the type of roads being driven i.e. motorways or what we term A and B roads but weight/mass are ineffective on all but motorways.

When one considers the weight of a an average man one can see that the larger heavier modern cars are sometimes carrying two or three additional men's worth of weight which affects everything - but more than anything it blunts all the responses.

Colin Chapman was so right 'to increase performance add lightness'

Chapman also said "“Adding power makes you faster on the straights; subtracting weight makes you faster everywhere”

Rather than consider power (and at redline rpm for that matter), you should consider available torque (at medium rpms) instead. At this point, people may wade in showing you a line on a graph of torque vs rpm - which is what people purchase when they go to a dyno. What you want to see is a graph of load vs rpm and the torque as a contour map layered onto this.

I suspect the v12 wins hands down but will be the more boring car to drive as the gradient of the slope all over the map will be flatter despite it being "higher" all over.

kind regards
Marek

Well, I find the 4.2 a VERY INTERESTING engine!! (I would say even more interesting than the V12....). It certainly sets a few records in MY book:

1) It is the lowest revving PETROL engine I have ever come across - pulling strong from below 500rpm but complaining from 4k rpm onwards. I have taken to shifting gears at 1200 - 1500rpm!;
2) it is lower revving than any modern passenger car diesel engine - My Land Rover TD5 was every so happy to rev up to 5k rpm - and pull strong all the way, my wife's diesel Freelander 2.2 SD4 is also much revvier than the 4.2;
3) It must have the heaviest pistons for all engines up to 4L made in the 60s/70s (not that I have wide knowledge on this. In terms of Kg/piston/liter-engine-displacement, it must be "up there" among the heaviest. Combined with very torquey cam, that explains why it does not like being revved much above 4K.

On the way home, I drove my V12 again. And fell in love all over again

You should try a Austin Healey 100.

The 4 cylinder, almost 3 liter engine can start in _any_ gear. A very low reving engine, too.

Tadek

As Simon says, you should try a good 3.8.

The 4.2 is a great all-rounder and very easy to live with but if responsiveness and revving beyond 4,000 floats your boat, the 3.8 is like a puppy on a leash. In fact the most ‘eager’ Jaguar I have ever owned - though not the absolute fastest - was a 3.8 Mk2 and that was on twin carbs! Considering the 3.8 and 4.2 E share everything above the head gasket, and dimensionally all but the bore/spacing and flywheel below it) it’s curious how different good examples can feel. The horsepower being ‘the same’ is artificial in that the outputs are calculated at differnt rev ceilings.

There’s just something about 3.8s that makes you want to floor it and enjoy the rush, instead of riding the wave of torque. A series 3 is a combination of both - providing revs and torque in abundance, with superb responsiveness in manual form, but it feels less ‘chuckable’.

mgcjag wrote: ↑

Sat Oct 10, 2020 12:43 pm

Chapman also said "“Adding power makes you faster on the straights; subtracting weight makes you faster everywhere”

True, but engines can be tested to destruction safely on a dyno and material reinstated if too much was removed for adequate durability. In most other areas, prior to computer modeling, you only found out too much weight had been removed when something broke, With Chapman’s exquisite cars, “faster everywhere “ included frequent off-piste excursions into the hay bales and Armco...

PeterCrespin wrote: ↑

Sun Oct 11, 2020 10:36 am

mgcjag wrote: ↑

Sat Oct 10, 2020 12:43 pm

Chapman also said "“Adding power makes you faster on the straights; subtracting weight makes you faster everywhere”

True, but engines can be tested to destruction safely on a dyno and material reinstated if too much was removed for adequate durability. In most other areas, prior to computer modeling, you only found out too much weight had been removed when something broke, With Chapman’s exquisite cars, “faster everywhere “ included frequent off-piste excursions into the hay bales and Armco...

The race drivers had two minds in the lotus didn't they - fast but fragile....

The V12 reminds me of Concorde - amazing technical achievement but not really needed / useful . An incident with my XJS comes to mind - going up a steep hill I put the autobox into 2 but then had to stop , started off again forgetting the trans was locked in 2 ( the same gear that was good for over 100 mph ) . No problem , it just pulled away as normal - unbelievable engine flexibility - impressive , but slightly pointless .

Maybe the V12 was more suited to a luxury limo where smoothness and refinement were needed , but for a sports model where people want excitement , a 6 would have been a better choice .

max-it-out wrote: ↑

Mon Oct 12, 2020 9:40 am

going up a steep hill I put the autobox into 2 but then had to stop , started off again forgetting the trans was locked in 2 ( the same gear that was good for over 100 mph ) . No problem , it just pulled away as normal -

I have (bad?) news for you Mark....

"2" on the transmission selector means : "1st or 2nd will be used whichever is appropriate."

Sooo... Your XJS did pull away in 1st (Unless it was a manual).

MY XJS is a 5-sp manual with a 0.68 5th. There is hardly a hill that she won't climb in 5th. The amazing thing about the V12 is how much torque it produces from idle up to 5000rpm and how flat that torque curve is.

Attached, the torque curve of my S3 OTS which I EFI'ed using HE hardware and Megasquirt-2

When I first started work I supplemented my income (to pay for my extortionate insurance to run a Mini Cooper) at a local fuel filling station on the weekends. On one shift this brand new V12 FHC etype stopped for fuel and I asked the owner whether he liked it - he was quite vocal in saying that he had owned each etype - series 1, 1.5, 2 and 3. His view was that the 3.8 remained his favourite...

My father owned a 3.8 and 4.2 FHC, his preference was always the 4.2, for myself the 3.8 has always felt the more dynamic and racy....

ysmalkie wrote: ↑

Sat Oct 10, 2020 7:14 pm

You should try a Austin Healey 100.

The 4 cylinder, almost 3 liter engine can start in _any_ gear. A very low reving engine, too.

Tadek

Hi Tadek

Don't know if you have checked your pm's, I left one for you a while back....

Richard

richard btype wrote: ↑

Mon Oct 12, 2020 11:20 am

for myself the 3.8 has always felt the more dynamic and racy....

I have owned quite a few Land Rover V8 engined vehicles, 3.9 Discovery 1, Discovery 2 4.0 (now converted to 4.6) and 4.6 Range Rover HSE. (I'll not mention my current 5.0L Supercharged Rangie....)

The "sweetest" of them all was my sister's Classic Range Rover with the 3.5 - until its crank broke (due to conrods being installed the wrong way round).

Ive had them all, imho the 4.2 series one is really the best, chuckable, light, powerful, and just charming to drive.........
gtjoey1314

I still want to test my 4.2 2+2 vs my Citroen SM 3.0 2+2... albeit the SM appeared in 1970, so the V12 would have been the opponent.

But first... I need to finish the E ...I‘m currently shopping for a windshield.

Carsten

This is very subjective. I love the look, the drive, the sound ,even the Moss gearbox on my 3,8 Ser 1 fhc, but then my Ser 3 2+2 was designed 10 years later and therefore has many improvements over the earlier car. I find the wider wheels and track give better handling, certainly make it easier to drive especially with power steering. The brakes are far better, electrics better and as for the engine, the V12 is a masterpiece of design. Having said all this I like them equally as much but for very different reasons.