Diesel to Petrol Cylinder Heads
Discussion
Right, been a while since I asked a stupid question, so ill ask another one
I own a Jag S-type, 3.0 V6 making 230BH and 300Nm, bore of 89, stroke of 79.5. the gearbox is apparently rated to 300Nm, meaning there is no room for any power modifications.
a Jag S-type also has a 2.7TDV6, making 204BH and 435Nm, Bore of 81, stroke of 88. the gearbox is apparently rated to 600Nm. which give plenty of room for modifications.
the Jag X-Type came with a 2.0V6 based off the 3.0 with a bore of 81.6, stroke of 66.
as far as I'm aware, the gearboxes are not interchangeable. after doing a small amount of research, I found that the bold pattern between the heads is very similar. So, in theory, the heads are interchangeable. as the heads could be changed, this would effect the CR. ive done calculations and if you put the 2.0V6 head on the 2.7TDV6, the CR drops to 7.2. this then creates a 2.7, twin turbo V6 with a gearbox rated up to 600Nm.
using the 3.0v6 head creates a CR of 9.4
my question is this, is this actually possible? assume that I would be changing ECUs and ancillaries.
also, could this work the other way round so a 3.0v6 with direct injection, (I know it would need another hole for spark plug)
I own a Jag S-type, 3.0 V6 making 230BH and 300Nm, bore of 89, stroke of 79.5. the gearbox is apparently rated to 300Nm, meaning there is no room for any power modifications.
a Jag S-type also has a 2.7TDV6, making 204BH and 435Nm, Bore of 81, stroke of 88. the gearbox is apparently rated to 600Nm. which give plenty of room for modifications.
the Jag X-Type came with a 2.0V6 based off the 3.0 with a bore of 81.6, stroke of 66.
as far as I'm aware, the gearboxes are not interchangeable. after doing a small amount of research, I found that the bold pattern between the heads is very similar. So, in theory, the heads are interchangeable. as the heads could be changed, this would effect the CR. ive done calculations and if you put the 2.0V6 head on the 2.7TDV6, the CR drops to 7.2. this then creates a 2.7, twin turbo V6 with a gearbox rated up to 600Nm.
using the 3.0v6 head creates a CR of 9.4
my question is this, is this actually possible? assume that I would be changing ECUs and ancillaries.
also, could this work the other way round so a 3.0v6 with direct injection, (I know it would need another hole for spark plug)
chammyman said:
The engines and heads are totally different.
Petrol pistons are flat for example and the diesels have a bowl in them.
Just go buy a v8 s-type they are cheap enough.
The CR calculations I made accounted for this, using the CR of the stock engines to calculate the volume of air left. Dishes Pistons are there to lower the CR and a re still usable in petrol engines, for example, mini1000 have dished Pistons Petrol pistons are flat for example and the diesels have a bowl in them.
Just go buy a v8 s-type they are cheap enough.
MaxRothery said:
The CR calculations I made accounted for this, using the CR of the stock engines to calculate the volume of air left. Dishes Pistons are there to lower the CR and a re still usable in petrol engines, for example, mini1000 have dished Pistons
Diesel pistons aren't like the dished pistons you get in a A-series engine. On a direct injection diesel the entire combustion chamber is effectively held within the piston crown. If you combined this with a typical pent roof petrol cylinder head you'd end up with a pretty dire combustion chamber shape, not to mention a set of extremely heavy pistons that would not be suitable for high RPM use. 7.2:1 is also a comically low compression ratio unless you are considering running some pretty extreme boost levels. It would make the engine very lethargic (and thirsty) off-boost.
227bhp said:
You haven't made it entirely clear what you are planning to do....
^^^ Wot 'e said.You mention these possibilities & calculations, but are you planning to put a petrol head on a diesel engine, vice versa or what?
Surely a petrol head has nothing like the CR required for diesel auto-ignition?
E-bmw said:
^^^ Wot 'e said.
You mention these possibilities & calculations, but are you planning to put a petrol head on a diesel engine, vice versa or what?
Surely a petrol head has nothing like the CR required for diesel auto-ignition?
It seems fairly clear to me: OP wants to put a petrol head on a diesel bottom end, run turbos to create a petrol engine making lots of power which the diesel gearbox will be able to take without breaking. However, using diesel pistons is a silly idea.You mention these possibilities & calculations, but are you planning to put a petrol head on a diesel engine, vice versa or what?
Surely a petrol head has nothing like the CR required for diesel auto-ignition?
Mr2Mike said:
E-bmw said:
^^^ Wot 'e said.
You mention these possibilities & calculations, but are you planning to put a petrol head on a diesel engine, vice versa or what?
Surely a petrol head has nothing like the CR required for diesel auto-ignition?
It seems fairly clear to me: OP wants to put a petrol head on a diesel bottom end, run turbos to create a petrol engine making lots of power which the diesel gearbox will be able to take without breaking. However, using diesel pistons is a silly idea.You mention these possibilities & calculations, but are you planning to put a petrol head on a diesel engine, vice versa or what?
Surely a petrol head has nothing like the CR required for diesel auto-ignition?
Mr2Mike said:
E-bmw said:
^^^ Wot 'e said.
You mention these possibilities & calculations, but are you planning to put a petrol head on a diesel engine, vice versa or what?
Surely a petrol head has nothing like the CR required for diesel auto-ignition?
It seems fairly clear to me: OP wants to put a petrol head on a diesel bottom end, run turbos to create a petrol engine making lots of power which the diesel gearbox will be able to take without breaking. However, using diesel pistons is a silly idea.You mention these possibilities & calculations, but are you planning to put a petrol head on a diesel engine, vice versa or what?
Surely a petrol head has nothing like the CR required for diesel auto-ignition?
MaxRothery said:
Correct, exactly what I want to do. So if I replaced the Pistons with lighter ones suitable for petrol, would that work?
It's probably doable given enough time and money. Does the petrol head really drop onto the diesel block, e.g. do all the bolt, water and oil passages align ok? Do the petrol and diesel share the same cam drive arrangement? You'd obviously need to sort out an ECU for fueling, and the rest of the cars systems are probably expecting to see various engine related data on a CAN bus so whatever ECU you used would have to do this. The crank & rods and flywheel are likely to be a bit on the heavy side for a petrol engine, and you'd need to make sure the flywheel was ok for the higher RPM. The you'd need custom exhaust manifolds for the turbos and all the water, oil, inlet and exhaust plumbing that goes with a turbo install.
It would almost certainly be less work to tune the 3.0V6 and fit a heavier duty gearbox, making whatever adapter plates are required. Or buy a V8
Mr2Mike said:
MaxRothery said:
Correct, exactly what I want to do. So if I replaced the Pistons with lighter ones suitable for petrol, would that work?
It's probably doable given enough time and money. Does the petrol head really drop onto the diesel block, e.g. do all the bolt, water and oil passages align ok? Do the petrol and diesel share the same cam drive arrangement? You'd obviously need to sort out an ECU for fueling, and the rest of the cars systems are probably expecting to see various engine related data on a CAN bus so whatever ECU you used would have to do this. The crank & rods and flywheel are likely to be a bit on the heavy side for a petrol engine, and you'd need to make sure the flywheel was ok for the higher RPM. The you'd need custom exhaust manifolds for the turbos and all the water, oil, inlet and exhaust plumbing that goes with a turbo install.
It would almost certainly be less work to tune the 3.0V6 and fit a heavier duty gearbox, making whatever adapter plates are required. Or buy a V8
I think the OP is assuming the 2 engines are related as they are both in jags ?
AFAIK the 3.0 V6 is based on a duratec (Mazda/Ford) and the 2.7 is based on a PSA engine(Citroen/Peugeot/Ford), the only 2 thing connecting them is Ford were involved in both engine developments and they are in a jag, they were developed over 10 years appart so if the bolt spacings are "a little out" most likely so are the waterways, oilways, cylinder bore spacing ect ect possably even head size, the gaskets certainly look very differant
3.0
2.7
Yes, i was bored
AFAIK the 3.0 V6 is based on a duratec (Mazda/Ford) and the 2.7 is based on a PSA engine(Citroen/Peugeot/Ford), the only 2 thing connecting them is Ford were involved in both engine developments and they are in a jag, they were developed over 10 years appart so if the bolt spacings are "a little out" most likely so are the waterways, oilways, cylinder bore spacing ect ect possably even head size, the gaskets certainly look very differant
3.0
2.7
Yes, i was bored
one eyed mick said:
Is this going in the indy suspended solid a rear axle Triumph 1300 shelled 4 wd concoction you have in mind ? if so grow up !!!
No, was just curious Besides, if I wanted just 4wd in it, there is a gearbox that I could fit but would have to use the 1500 engine which isn't the best in term of power
Edited by MaxRothery on Saturday 13th February 14:46
Unless you are thinking of making a VERY large amount of power (>250bhp/l) then there is no point in using the diesel block just to get a different gearbox imo. Diesels make huge cylinder pressure at low rpm to make high power, with a petrol engine with twice the rev capability you don't need to make such huge cylinder pressure and hence don't need such a strong block. Much much easier just to make a gearbox adaptor plate to mate the stronger box to the gasoline block!
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