70s Grand Prix car

In reply to ferrariwill :

Ferrari dominated with their V12,  Jaguar designed a V12 in 1954 but didn't build it until 1971 when it was designed to go out to 8  liters. To compete with the big American V8's. 
Do not confuse V8's with more horsepower. Chevy 350's had 350 horsepower one year and the next year it was 160 horsepower.  It wasn't about smog equipment. One was advertised horsepower rated ( sometimes called gross horsepower) and the other was as the engine was actually installed in a car. 
At the same time a Chevy 350 was 160 horsepower Net. The Jag V12 was 242 horsepower net DIN  built to USA specs which is slightly less than the SAE net horsepower rating. Apples to Apples the Jaguar V12 is about 248 horsepower if I remember correctly  British and global specs increased that to 258 hp. Later that same V12  engine went to 262 , 289, or  299 depending on which specs it has. 
the 454 Chevy which weighs about what the. V12 does, one year it was 450 advertised horsepower and the next year was 280-290 or 305 SAE net depending on application .  
A 90 degree V8 is wider than the 60 degree V12  by several inches as well as having the spark plugs on its side and while the V12  is slightly by 2 or 3 inches longer than the V8  remember that engine is designed to go over 500 cu in. Most Chevy's are not suitable for racing with a cast crank, cast pistons, hydraulic lifters, small valves, cast Iron block, heads, intake manifolds,  and an exhaust system that loses over 15% power without proper headers.

The Jaguar stock has aluminum block heads manifold s  etc. a forged crankshaft, solid lifters,  4 really big carburetors with 1&3/4 butterflies. Bigger than a Holley Dominator. The stock 4 pound cast iron exhaust manifolds are very efficient, gaining only 4-5% more with properly designed racing headers. ( that are heavier than the stock cast iron manifolds) 

In reply to frenchyd :

In the 1970's Formula 5000 became semi popular. Most of those used the Chevy 350 engine with the 3 inch crankshaft. For 305 cu in or 5 liters.  
As they aged out of competitiveness and waited for Vintage racing to accept them, most of those took the car and used the 350 cu inch engine or even bigger.  
However built to racing spec's the parts alone cost $15-20,000  plus machine and building.  Backyard engines could be built for less but simply weren't competitive or reliable.  

In reply to frenchyd :

Very interesting.  I think the pre HE is 268-272 HP in Britain from XJ12 or E-type when fitted with Stromberg CD175s.  Later pre HEs were a little more peaking in 1980 with 10:1 compression ratio - not sure if this was the case in USA.

I have spent some time thinking about the cylinder head design and have come to the conclusion that it will be very difficult to manufacture.  The mould cores for the inlet and exhaust will be very complex without resorting to 3D printing which I probably cannot afford.  The same is true of the cores that would be required for the coolant passages within the head.

So, It might be worth looking at an off the shelf head, with a bespoke block.  Maybe this strategy would work well a flat 12?  I like the approach of the early 70s 312 Ferrari engine is this regard.  I have a couple of Jaguar heads which could be used as a start.

I will have a brief look and see what could be achieved.

In reply to ferrariwill :

If you want 4 valve per head 4 cam engines it has been done using all Jaguar parts.  
the in line six 3.5-4.0 engine is basically 1/2 a V12  one side pretty well bolts on.  The other side needs to be reversed but the factory did it and a guy in Australia did it.  
it's a lot easier than trying to make  your own engine.  ( or spending the really silly dollars it would take to buy a Ferrari.) 

Your numbers are likely correct regarding horsepower on the British versions.  They had 9.0-1 compression and no smog regulations to comply with while America had 7.8-1 compression and California smog regulations to comply with.  
For 1/2 a year 1980-1981 England had 10.0-1  compression. 
 

In reply to frenchyd :

Yes that is true that it will bolt on, however I think AJ6/AJ16 is 4 studs around each bore; the reason so I'm told is that the AJ6 is designed to be simaised bore closed deck for Diesel versions that never came to be?

V12 has 4 large studs and 2 smaller ones.  I'm not sure there's an easy way aorund this.  I presume that all 6 are required to get the required clamping load through the gasket onto the sleeve land.

Presumably putting a head that's designed to fit on a closed deck block on an open deck one might invite trouble?  For sure Jaguar went the other way round with 2.9 litre XJ40 which had a single V12 head on an AJ6.

What are your thoughts?

The idea of a flat 12 is growing on me - some sort of hybrid, using various bits of Jaguar and some parts from scratch.  It would have a very low CoG and could allow some interesting package options around the rear suspension/transaxle?

What about a Toyota V8 or V12? The 1GZ-FE sounds amazing here: 

https://youtu.be/Iyw20RCk8Yo

I think he built those ITB's from sport bike parts.

http://www.speedhunters.com/2017/06/rolling-double-six-v12-toyota-mark-ii/

It's all aluminum, 4 cam, and cheap. 

There are probably a lot more speed parts out there for the 1UZ-FE V8. Not sure if its cross or flat plane.

In reply to mblommel :

I like the UZ but the timing chest seems difficult to attach to the tub due to the belt drive; might make it difficult to stress the block?

I'm thinking I would prefer to go with a flat 12 if it's possible.

Decision time.

The engine will be 12 cylinders horizontally opposed, non-siamised bore with damp (axially clamped) liners.  Objective is low CoG, reasonable weight (around 500-550 lbs wet), ability to be stressed member of the chassis.  High revs and high peak power are desirable; it’s not really a “sports car” engine, really a bit closer to a race engine.  Big end journals shared across the block i.e. cylinder 1 and 7 use the same crank pin.  Many parts will be (at least initially) be from Jaguar.  Presently, this includes complete head assembly, possibly crank, rods and pistons.

It would be an advantage to create a basic design which can be grown in terms of power output.  This may be achieved later by more aggressive bore/stroke ratios, more revs, 4 valves/cylinder, DOHC etc..

It is an advantage to have an electric start because it is very convenient, even if it adds weight.  This will likely be a Denso (or equivalent) reduction type acting on a ring gear about the flywheel like a road car. Likewise, I plan to run provision for an alternator from an auxiliary drive belt.  If the car will be used for short periods i.e. less than one hour, it can be removed, but it’s a handy option later on if required.

Electric water pump(s) are beneficial because they greatly simplify the layout in the front of the block, thus improving weight and packaging.  They also permit each bank to be cooled completely independently, which is some applications may be a great advantage.

The plan is to use multi point EFI, one injector into the runner of each cylinder.  For complexity of drive reasons, plus dwell time, it is difficult to get points and condenser ignition working on 12 cylinders.  A split system (2 x 6 cylinder) with 2 coils and distributors is possible, but packaging and driving them is mechanically complex.  Lucas OPUS (as per early Jag V12) is good, but I do not think it will support good spark quality with high(ish) volumetric efficiency at race engine speeds.  As such, I would like to look at hall effect electronic coil pack ignition, run by ECU.

Bore:                                     90/91 mm

Stroke:                                 70 mm

Bore to stroke ratio:        1.285:1 or 1.3:1 depending on bore. (BRM V12 GP engine is 1.28:1, Cosworth DFV is 1.32:1)

Total Displacement:        5.3/5.4 litres depending on bore

Cylinder Displacement:  445 cc (5.3 litre)

Max speed:                        8,500 RPM

Valves:                                 SOHC/bank, 2 valve/cylinder.  Head as pre-HE Jag V12

Compression ratio:          10.0:1 (as per 1980 model pre-HE)

Ignition:                               coil pack (no distributor) from ECU (aftermarket?)